DE212025000035U1 - Battery cells, battery devices and electrical devices - Google Patents

Abstract

Battery cell comprising an electrode arrangement and an electrolyte solution, wherein the electrode arrangement comprises positive electrode plates and negative electrode plates stacked along the thickness direction of the battery cell.
the positive electrode plate comprises a positive current collector and positive membrane layer(s) arranged on at least one side of the positive current collector, the positive membrane layer comprising lithium-containing phosphates with an olivine structure;
the negative electrode plate comprises a negative current collector and negative membrane layer(s) arranged on at least one side of the negative current collector, the negative membrane layer comprising graphite particles;
The electrolyte solution comprises carboxylic acid ester solvents, linear carbonate solvents and additives, wherein, based on the mass of the electrolyte solution,
the mass content of carboxylic acid ester solvents is 10% to 30% and the mass content of linear carbonate solvents is 10% to 50%;
The mass content of the additives is 3% to 9%, wherein the additives include propane-1,3-sultone with a mass content of ≥ 0, ethylene carbonate derivatives with a mass content of ≥ 0 and vinylidene carbonate with a mass content of > 0.
where ethylene carbonate derivatives contain the compounds shown in formula A,
In formula A, Q1, Q2, Q3 and Q4 each independently contain any one of a hydrogen atom, a halogen atom, a Cl-C5 alkyl group or a Cl-C5 haloalkyl group, where Q1, Q2, Q3 and Q4 are not simultaneously hydrogen atoms.

Description

TECHNICAL AREA

The application concerns a battery cell, a battery device and an electrical device.

TECHNICAL BACKGROUND

Battery cells are characterized by high capacity and long lifespan, and are therefore widely used in electronic devices such as mobile phones, laptops, e-bikes, electric cars, electric aircraft, electric ships, and power tools. As the applications of lithium-ion batteries continue to evolve, the demands on the properties of the battery cells are also increasing, for example, regarding fast charging capability and cycle stability.

CONTENT OF THE INVENTION

The application relates to a battery cell, a battery device and an electrical device that improve the fast charging capability and cycle stability of the battery cell.

The first aspect of this application relates to a battery cell comprising an electrode arrangement and an electrolyte solution, wherein the electrode arrangement comprises positive and negative electrode plates stacked one above the other along the thickness direction of the battery cell. The positive electrode plate comprises a positive current collector and positive membrane layer(s) arranged on at least one side of the positive current collector, the positive membrane layer comprising lithium-containing phosphates with an olivine structure; the negative electrode plate comprises a negative current collector and negative membrane layer(s) arranged on at least one side of the negative current collector, the negative membrane layer comprising graphite particles;

The electrolyte solution comprises carboxylic acid ester solvents, linear carbonate solvents, and additives, wherein the mass fraction of carboxylic acid ester solvents is 10% to 30% and the mass fraction of linear carbonate solvents is 10% to 50%. The mass fraction of the additives is 3% to 9%, based on the mass of the electrolyte solution, wherein the additives include propane-1,3-sultone at a mass fraction of ≥ 0, ethylene carbonate derivatives at a mass fraction of ≥ 0, and vinylidene carbonate at a mass fraction of > 0, wherein the ethylene carbonate derivatives contain the compounds shown in Formula A.

In formula A, _Q1 , _Q2 , _Q3 and _Q4 each contain independently a hydrogen atom, a halogen atom, a C1-C5 alkyl group or a Cl-C5 halogen alkyl group, where _Q1 , _Q2 , _Q3 and _Q4 are not simultaneously hydrogen atoms.

Therefore, in the embodiments of the application, active ions, such as lithium ions, migrate from the positive electrode plate through the electrolyte solution to the negative electrode plate during the charging process. The electrolyte solution contains carboxylic acid ester solvents, which reduce the viscosity of the electrolyte solution and increase the migration rate of the lithium ions. With increasing mass concentration of the carboxylic acid ester solvent, the viscosity of the electrolyte solution decreases, the electrical conductivity increases, and the migration rate of the lithium ions in the electrolyte solution can be further increased, which benefits the fast-charging capability. However, with further increasing mass concentrations of the carboxylic acid ester solvent, stronger side reactions occur between the carboxylic acid ester solvent and the negative active material, resulting in the formation of more gas. The electrolyte solution also contains linear carbonate solvents. The addition of linear carbonate solvents allows the electrolyte solution to exhibit relatively high electrical conductivity even with a small addition of carboxylic acid ester solvents, thus increasing the migration rate of the lithium ions. The electrolyte solution is enhanced. Furthermore, due to their relatively low mass fraction, the carboxylic ester solvents slow down side reactions and reduce gas formation. The electrolyte solution also contains additives, including vinylidene carbonate. The reaction potentials of vinylidene carbonate and carboxylic ester solvents are similar, resulting in a competitive reaction between them. Vinylidene carbonate can contribute to the formation of a dense solid electrolyte interface (SEI) layer with organic components on the negative electrode side, making it difficult for carboxylic ester solvents to penetrate the SEI layer to the negative active material. This further mitigates side reactions between the carboxylic ester solvents and the negative active material and further reduces gas formation. Since the additives are present in appropriate amounts, the membrane impedance on the negative electrode side is not excessively high, so the fast-charging capability is essentially unaffected. Therefore, the present application can improve the fast-charging capability and cycle stability of the battery cells.

In some embodiments, the mass content of the additive is 5% to 8%. The mass content of the additives is within the aforementioned range, which further improves the cycle stability and fast-charging capability of the battery cells.

In some embodiments, the mass fraction of vinylidene carbonate is 0.8% to 7%, optionally 2% to 6%. When the mass fraction of vinylidene carbonate is within the aforementioned range, a dense SEI layer containing organic components can form on the negative electrode side. Furthermore, the resistance of the SEI layer is relatively low, which reduces side reactions on the negative electrode side and improves both the cycle life and the fast-charging capability of the battery cells.

In some embodiments, the mass fraction of propane-1,3-sultone in the electrolyte solution is 0% to 0.5%. If the mass fraction of propane-1,3-sultone is within the aforementioned range, the resistance of the formed SEI layer cannot become too high, thereby reducing resistance and improving the fast-charging capability and cycle stability of the battery cells by mitigating side reactions.

In some embodiments, the mass content of ethylene carbonate derivatives in the electrolyte solution is 0% to 2.55%. Ethylene carbonate derivatives preferably form a membrane, optimizing the composition of the SEI membrane, reducing its resistance, and thus improving the fast-charging capability and cycle stability of the battery cells.

In some embodiments, at least one of the residues _Q1 , _Q2 , _Q3 , and _Q4 may contain halogen atoms or C1-C5 haloalkyl residues. If ethylene carbonate derivatives contain fluorine atoms, they can form an F- and Li-rich membrane layer on the negative electrode side, which protects the negative active materials while simultaneously reducing the resistance of the membrane layer, thereby improving the cycle stability and fast-charging capability of the battery cells.

In some embodiments, ethylene carbonate derivatives comprise at least one compound of formula A-1 to formula A-3,

The materials mentioned above can further improve the cycle stability and fast-charging capability of the battery cells.

In some embodiments, the electrical conductivity of the electrolyte solution is 11 ms/cm to 14 ms/cm, with the higher electrical conductivity of the electrolyte solution contributing to the improvement of the fast charging capability of the battery cells.

In some embodiments, carboxylic acid ester solvents comprise at least one of ethyl acrylate, propyl acetate, ethyl propionate, ethyl formate, propyl formate, ethyl acetate, or butyl propionate. The aforementioned materials exhibit lower viscosity, which can further improve the fast-charging capability of the battery cells.

In some embodiments, linear carbonate solvents comprise at least one of dimethyl carbonate, diethyl carbonate, and methyl carbonate. The aforementioned materials exhibit a relatively low viscosity, which improves the electrical conductivity of the electrolyte solution at room temperature and increases the fast-charging capability of the battery cells.

In some embodiments, the electrolyte solution also includes cyclic carbonate solvents, with the mass fraction of the cyclic carbonate solvents in the electrolyte solution being between 20% and 50%. Cyclic carbonate solvents possess excellent desolventing properties, which enable lithium ions to rapidly detach from the solution structure at the interface between the positive and negative electrodes, thereby increasing the mobility of the lithium ions at the interface and thus further improving the fast-charging capability of the battery cells.

In some embodiments, the cyclic carbonate solvents comprise at least one of ethylene carbonate, propylene carbonate, and butylene carbonate. The aforementioned materials possess excellent desolventization properties, thereby increasing the mobility of lithium ions at the interface and further improving the fast-charging capability of the battery cells.

In some embodiments, the electrolyte solution also includes lithium salt additives, wherein the lithium salt additives comprise at least one of lithium difluorophosphate, lithium fluorosulfonate, lithium difluorooxalate borate, lithium tetrafluoroborate, and lithium bisoxalate borate. The aforementioned additives improve the properties of the SEI layer on the negative electrode side, thereby increasing the fast-charging capability of the battery cells and improving their cycle life.

In some embodiments, the mass fraction of lithium salt additives in the electrolyte solution is 0.02% to 0.5%. Lithium salt additives and other additives contribute to membrane formation and optimize the composition of the SEI membrane. The lithium salt additives contribute to the formation of an inorganic SEI membrane, with the inorganic components increasing the high-temperature and high-pressure stability of the SEI membrane and thus improving the cycle life of the battery cells.

In some embodiments, the dense density of the negative membrane layer in a discharged battery cell (SOC 0%) is 1.30 g/ ^cm³ to 1.52 g/ ^cm³ . When the dense density of the negative membrane layer is within the aforementioned range, the energy density of the battery cells is increased. Because the negative active material of the negative electrode plate is more densely packed, the contact resistance between the particles is lower, further reducing the resistance of the electrode plate. This reduces heat generation and thus the amount of gas produced by the decomposition of carboxylic acid ester solvents due to heat generation, thereby improving the cycle life of the battery cells.

In some embodiments, the one-sided coating weight of the negative membrane layer is 120 mg/1540.25 ^mm² to 180 mg/1540.25 ^mm² . If the one-sided coating weight of the negative membrane layer is within the above-mentioned range, the heat generation per unit area of the negative electrode plate will not be excessively high, thereby improving the cycle stability of the battery cells.

In some embodiments, the graphite particles comprise the graphite particles themselves and a negative coating covering the surface of the graphite particles themselves, wherein the graphite particles themselves comprise secondary particles and the negative coating comprises carbon elements.

In some embodiments, the graphite particles themselves comprise at least one of artificial graphite and one of natural graphite.

In some embodiments, the graphitization degree of the graphite particles is 90% to 94%. When the graphitization degree of the graphite particles is within the aforementioned range, the graphite particles exhibit excellent electrical conductivity, thereby reducing heat generation in the negative electrode plate and battery cells, and improving the fast-charging capability of the battery cells.

In some embodiments, the volume-related average particle size Dv50 of the graphite particles is 7 µm to 15 µm. The volume-related average particle size of the graphite particles is relatively small, which shortens the migration paths of the lithium ions in the solid electrode materials and improves the fast-charging capability of the battery cells.

In some embodiments, the thickness of the negative coating can range between 100 nm and 500 nm. If the thickness of the negative coating is within the aforementioned range, the conductivity of the graphite particles can be further improved, the internal resistance of the negative electrode plate reduced, the heat generation of the battery cells reduced, and the cycle life of the battery cells improved.

In some embodiments, the negative membrane layer also includes a silicon-based material, wherein the mass fraction of silicon in the silicon-based material in the negative membrane layer is between 0.5% and 10.0%. If the mass fraction of the silicon element in the silicon-based material is within the aforementioned range, the capacity of the negative active material can be increased and the energy density of the battery cells improved.

In some embodiments, the negative membrane layer comprises a first negative membrane layer and a second negative membrane layer, wherein the first negative membrane layer is arranged on the surface of the negative current collector and the second negative membrane layer is arranged on the side of the first negative membrane layer facing away from the negative current collector, wherein both the first negative membrane layer and the second negative membrane layer contain graphite particles, wherein the average longest diameter of the graphite particles in the first negative membrane layer is greater than or equal to the average longest diameter of the graphite particles in the second negative membrane layer.

This allows the different particle sizes in the first and second negative membrane layers to improve the fast-charging capability of the battery cells. Specifically, during fast charging, the overpotential of the second negative membrane layer is typically higher, meaning the bottleneck during fast charging is primarily in this layer. Since the particle size in the second negative membrane layer is relatively small in the present application, the transport path of the lithium ions in the solid electrode materials can be shortened, the fast-charging capability improved, and lithium plating on the surface of the negative electrode plate reduced.

In some embodiments, the average longest diameter of the graphite particles in the first negative membrane layer is between 7 µm and 18 µm. If the average longest diameter of the graphite particles in the first negative membrane layer is within the aforementioned range, the lithium-ion transport path can be shortened and the fast-charging capability improved, while at the same time, less clumping occurs during manufacturing, thus increasing the stability of the material.

In some embodiments, the average longest diameter of the graphite particles in the second negative membrane layer is between 6 µm and 10 µm. When the average longest diameter of the graphite particles in the second negative membrane layer is within the aforementioned range, the lithium-ion transport path can be shortened, improving fast-charging capability. Furthermore, less clumping occurs during manufacturing, thereby increasing the material's stability. Additionally, combining the negative active material in the second negative membrane layer with the negative active material in the first negative membrane layer within the aforementioned particle size range promotes the formation of a porosity gradient between the second and first negative membrane layers. This reduces the impedance of lithium-ion transport and further improves the fast-charging capability of the battery cells.

In some embodiments, the ratio between the thickness of the second negative membrane layer and the thickness of the negative membrane layer is 0.3 to 0.7. By adjusting the thickness fraction of the first negative membrane layer, the porosity gradient between the upper and lower layers can be further increased, the impedance to lithium ion transport reduced, and the fast-charging capability of the battery cells improved.

In some embodiments, the dense density of the positive membrane layer in a battery cell in the discharged state (SOC 0%) is 2.3 g/ ^cm³ to 2.6 g/ ^cm³ . When the dense density of the positive membrane layer is within the aforementioned range, the energy density of the battery cells is increased. Since the positive active material of the positive electrode plate is more densely packed, the contact resistance between the particles is lower, further reducing the resistance of the electrode plate. This reduces heat generation during fast charging and improves the cycle stability and fast-charging capability of the battery cells.

In some embodiments, the one-sided coating weight of the positive membrane layer is 250 mg/1540.25 ^mm² to 330 mg/1540.25 ^mm² . If the one-sided coating weight of the positive membrane layer is within the above-mentioned range, the heat generation per unit area of the positive electrode plate will not be excessively high, thereby improving the cycle stability and fast-charging capability of the battery cells.

In some embodiments, the lithium-containing phosphates comprise at least one primary particle and secondary particles, wherein the secondary particles comprise several primary particles and are spherical and/or nearly spherical. The migration paths of the lithium ions in the primary particles are short, which increases the migration rate of the lithium ions. Furthermore, the secondary particles are spherical and/or nearly spherical, thereby multiplying the migration paths, which further increases the migration rate of the lithium ions and improves the fast-charging capability of the battery cells.

In some embodiments, the average longest diameter of the primary particles is between 300 nm and 800 nm. When the average longest diameter of the primary particles is within the aforementioned range, the migration path of the lithium ions in the solid electrode materials is short, which further increases the migration rate of the lithium ions and improves the fast-charging capability of the battery cells.

In some embodiments, the average longest diameter of the secondary particles is between 5 µm and 15 µm. When the average diameter of the secondary particles is within the aforementioned range, the migration path of the lithium ions in the solid electrode materials is short, which further increases the migration rate of the lithium ions and improves the fast-charging capability of the battery cells.

In some embodiments, the lithium-containing phosphates comprise phosphate particles and positive additive elements located within the phosphate particles, wherein the positive additive elements include at least one of aluminum, vanadium, titanium, and niobium. The aforementioned additive elements for the positive electrode improve the crystal structure stability of the positive active material, increase the compressive strength of lithium-containing phosphates, contribute to improving the compacted density of the positive membrane layer, and increase the energy density and cycle life of the battery cells.

In some embodiments, the mass content of aluminum in the lithium-containing phosphates ranges from 200 ppm to 2500 ppm. When the mass content of aluminum is within the aforementioned range, the compressive strength of lithium-containing phosphates can be improved, which has a positive effect on the density of the positive membrane layer, the energy density of the battery cells, and the cycle life.

In some embodiments, the mass content of vanadium in the lithium-containing phosphates is 300 ppm to 2000 ppm. When the mass content of the element vanadium is in the above-mentioned range, the compacted density of the positive membrane layer is increased, thereby improving the energy density and cycle stability of the battery cells.

In some embodiments, the mass content of titanium in the lithium-containing phosphates is 1500 ppm to 3500 ppm. If the mass content of the element titanium is in the above-mentioned range, The crystal structure of the positive active material can be further improved and the cycle stability increased.

In some embodiments, the mass content of niobium in the lithium-containing phosphates ranges from 300 ppm to 2000 ppm. If the mass content of the element niobium is within the aforementioned range, the crystal structure of the positive active material can be further improved and the cycle stability increased.

In some embodiments, phosphate particles include lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate. The materials mentioned above exhibit excellent cycle stability and improve the cycle life of the battery cells.

In some embodiments, lithium-containing phosphates comprise compounds of the general formula Li _x1 A _y1 Me _a1 M _b1 P _1-c1 X _c1 Y _z1 , wherein 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.5 ≤ x 1 + y1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5, where A comprises at least one of Na, K and Mg; Me comprises at least one of Mn, Fe, Co and Ni; M comprises at least one of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X comprises at least one of Cl, C, and N; Y comprises at least one of O and F. Lithium-containing phosphates exhibit excellent cycle stability, which improves the cycle life of the battery cells.

In some embodiments, the positive electrode plate comprises at least one positive electrode tab, wherein at least one positive electrode tab is connected to the positive current collector and extends along the longitudinal direction of the battery cell outwards from the positive current collector. This arrangement helps to reduce the space required for the electrode tabs and to increase the energy density of the battery cell.

In some embodiments, the negative electrode plate comprises at least one negative electrode tab, wherein at least one negative electrode tab is connected to the negative current collector and extends out of the negative current collector along the longitudinal direction of the battery cell. This arrangement helps to reduce the space required for the electrode tabs and to increase the energy density of the battery cells.

In some embodiments, the positive electrode plate has: n*W1/W2 is 0.9 to 1.0; n denotes the number of all positive electrode tabs located on the same side of the positive current collector; W I denotes the average dimension of the positive electrode tabs along the width direction of the battery cell; W2 denotes the dimension of the positive current collector along the width direction.

It follows that if n*W1/W2 fulfills the above-mentioned range, the area of the positive electrode tab for overcurrent is relatively large, which improves the fast charging capability of the battery cell.

In some embodiments, the negative electrode plate fulfills: m*W3/W4 is 0.9 to 1.0; m denotes the number of all negative electrode tabs located on the same side of the negative current collector; W3 denotes the average dimension of the negative electrode tabs along the width direction of the battery cell; W4 denotes the dimension of the negative current collector along the width direction.

It follows that if m*W3/W4 fulfills the above-mentioned range, the area of the negative electrode tab for overcurrent is relatively large, which improves the fast charging capability of the battery cell.

In some embodiments, the battery cell also includes a positive terminal and a positive adapter, wherein the positive terminal is arranged on at least one side of the electrode assembly in the width direction of the battery cell and the positive terminal is connected to the positive electrode tab via the positive adapter. The connection via the positive adapter increases the overcurrent capability between the positive terminal and the positive electrode tab and improves the fast-charging capability of the battery cell.

In some embodiments, the battery cell also includes a negative terminal and a negative adapter, the negative terminal being located on at least one side of the electrode arrangement in The negative terminal is arranged in the width direction, and the negative terminal is connected to the negative electrode tab via the negative adapter. This connection via the negative adapter increases the overcurrent capability between the negative terminal and the negative electrode tab, thus improving the fast-charging capability of the battery cell.

In some embodiments, the thickness of the positive adapter ranges from 1.25 mm to 3.00 mm. The positive adapter is relatively thick and offers excellent overcurrent capability, further improving the fast-charging capability of the battery cells.

In some embodiments, the thickness of the negative adapter is 1.50 mm to 2.50 mm. The negative adapter is relatively thick and has excellent overcurrent capability, further improving the fast-charging capability of the battery cell.

In some embodiments, the positive adapter comprises a first positive adapter section and a second positive adapter section, the first positive adapter section being connected to the positive electrode tab. The second positive adapter section is connected to the first positive adapter section and projects longitudinally from the first positive adapter section. The second positive adapter section is connected to the positive terminal. The ratio of the width of the first positive adapter section to the width of the battery cell is between 0.2 and 0.5. When the width of the first positive adapter section is within this range, the path taken by electrons from the positive electrode tab, through the positive adapter, to the positive terminal is relatively short, thus improving the fast-charging capability of the battery cell.

In some embodiments, the ratio of the longitudinal dimension of the second positive adapter section to the length of the battery cell is between 0.05 and 0.2. If the ratio of the longitudinal dimension of the second positive adapter section to the length of the battery cell is within the aforementioned range, the path that electrons travel from the positive electrode tab via the positive adapter to the positive terminal is relatively short, thereby improving the fast-charging capability of the battery cell.

In some embodiments, the negative adapter comprises a first negative adapter section and a second negative adapter section, the first negative adapter section being connected to the negative electrode tab. The second negative adapter section is connected to the first negative adapter section and projects longitudinally from the first negative adapter section. The second negative adapter section is connected to the negative terminal. The ratio of the width of the first negative adapter section to the width of the battery cell is between 0.2 and 0.5. When the width of the first negative adapter section to the width of the battery cell is within the aforementioned range, the path that electrons travel from the negative electrode tab, through the negative adapter, to the negative terminal is relatively short, thus improving the fast-charging capability of the battery cell.

In some embodiments, the ratio of the longitudinal dimension of the second negative adapter section to the length of the battery cell is between 0.05 and 0.2. If the ratio of the longitudinal dimension of the second negative adapter section to the length of the battery cell is within the aforementioned range, the path that electrons travel from the negative electrode tab via the negative adapter to the negative terminal is relatively short, thus improving the fast-charging capability of the battery cell.

In some embodiments, the battery cell length is between 200 mm and 400 mm; if the battery cell length is within the aforementioned range, the energy density of the battery cell can be increased. Furthermore, the longitudinal electron transfer path is not too long, which improves the battery cell's fast-charging capability.

In some embodiments, the width of the battery cell is between 80 mm and 130 mm; if the width of the battery cell is within the aforementioned range, the energy density of the battery cell can be increased. Furthermore, the path of electron transfer in the lateral direction is not too long, which improves the fast-charging capability of the battery cell.

In some embodiments, the thickness of the battery cell ranges from 25 mm to 60 mm. If the thickness of the battery cell is within the aforementioned range, the internal heat of the battery cell can be dissipated quickly, thereby reducing the risk of electrolyte degradation due to heat accumulation and improving the cycle life of the battery cell.

In the second aspect, this application presents a battery device comprising one or more battery cells according to any embodiment of the first aspect of the application.

In the third aspect, this application presents an electrical device comprising a battery device according to any embodiment of the second aspect of the application.

BRIEF DESCRIPTION OF THE DRAWINGS

• 1 ist ein schematisches Strukturdiagramm einer Batteriezelle gemäß einigen Ausführungsformen der Anmeldung,
• 2 ist eine Explosionszeichnung einer Batteriezelle gemäß einigen Ausführungsformen der Anmeldung,
• 3 ist ein schematisches Strukturdiagramm der Elektrodenanordnung einer Batteriezelle gemäß einigen Ausführungsformen der Anmeldung,
• 4 ist ein schematisches Strukturdiagramm einer positiven Elektrodenplatte der Batteriezelle gemäß einigen Ausführungsformen der Anmeldung,
• 5 ist ein schematisches Strukturdiagramm einer positiven Elektrodenplatte der Batteriezelle gemäß weiteren Ausführungsformen der Anmeldung,
• 6 ist ein schematisches Strukturdiagramm einer positiven Elektrodenplatte der Batteriezelle gemäß weiteren Ausführungsformen der Anmeldung,
• 7 ist ein schematisches Strukturdiagramm einer positiven Elektrodenplatte der Batteriezelle gemäß weiteren Ausführungsformen der Anmeldung,
• 8 ist ein schematisches Strukturdiagramm einer negativen Elektrodenplatte der Batteriezelle gemäß einigen Ausführungsformen der Anmeldung,
• 9 ist ein schematisches Strukturdiagramm einer negativen Elektrodenplatte der Batteriezelle gemäß weiteren Ausführungsformen der Anmeldung,
• 10 ist eine Explosionszeichnung einer Batteriezelle gemäß weiteren Ausführungsformen der Anmeldung,
• 11 ist ein schematisches Strukturdiagramm eines positiven Adapters der Batteriezelle gemäß einigen Ausführungsformen der Anmeldung,
• 12 ist ein schematisches Strukturdiagramm eines negativen Adapters der Batteriezelle gemäß einigen Ausführungsformen der Anmeldung,
• 13 ist ein schematisches Strukturdiagramm eines Batteriemoduls gemäß einigen Ausführungsformen der Anmeldung,
• 14 ist ein schematisches Strukturdiagramm eines Batteriepacks gemäß einigen Ausführungsformen der Anmeldung,
• 15 ist ein schematisches Strukturdiagramm einer elektrischen Vorrichtung gemäß einigen Ausführungsformen der Anmeldung,

To more clearly illustrate the technical solution of the embodiment of this application, the drawings required for this embodiment are briefly presented below. It is evident that the drawings described below represent only some embodiments of this application and that a person skilled in the art in this field can create further drawings based on the attached drawings without any creative effort.

• 1 is a schematic structure diagram of a battery cell according to some embodiments of the application,
• 2 is an exploded view of a battery cell according to some embodiments of the application,
• 3 is a schematic structural diagram of the electrode arrangement of a battery cell according to some embodiments of the application,
• 4 is a schematic structural diagram of a positive electrode plate of the battery cell according to some embodiments of the application,
• 5 is a schematic structure diagram of a positive electrode plate of the battery cell according to further embodiments of the application,
• 6 is a schematic structure diagram of a positive electrode plate of the battery cell according to further embodiments of the application,
• 7 is a schematic structure diagram of a positive electrode plate of the battery cell according to further embodiments of the application,
• 8 is a schematic structural diagram of a negative electrode plate of the battery cell according to some embodiments of the application,
• 9 is a schematic structure diagram of a negative electrode plate of the battery cell according to further embodiments of the application,
• 10 is an exploded view of a battery cell according to further embodiments of the application,
• 11 is a schematic structure diagram of a positive adapter of the battery cell according to some embodiments of the application,
• 12 is a schematic structure diagram of a negative adapter of the battery cell according to some embodiments of the application,
• 13 is a schematic structural diagram of a battery module according to some embodiments of the application,
• 14 is a schematic structure diagram of a battery pack according to some embodiments of the application,
• 15 is a schematic structure diagram of an electrical device according to some embodiments of the application,

The attached images do not necessarily reflect the actual conditions.

EXPLANATION OF THE ENCLOSED DRAWINGS

X: Thickness direction; Y: Width direction; Z: Length direction
1. Electrical device; 2. Battery pack; 3. Control unit; 4. Motor; 5. Battery housing; 5a. First battery housing part; 5b. Second battery housing part; 5c. Receptacle; 6. Battery module;
7, battery cells;
10. Electrode arrangement;
11, Positive electrode plate; 111, Positive electrode tab; 1111, First contact point; 112, Positive current collector;
12, Negative electrode plate; 121, Negative electrode tab; 1211, Second contact point; 122, Negative current collector;
13, Separator
20, Housing; 21, Base housing; 22, Cover plate;
31, Positive terminal; 32, Negative terminal;
41, Positive adapter; 411, First positive adapter section; 412, Second positive adapter section;
42, Negative adapter; 421, First negative adapter section; 422, Second negative adapter section;

DESCRIPTION OF THE EXECUTION FORMS

The embodiments of the battery cell, the battery device, and the electrical device of the present application are explained in detail below with reference to the accompanying drawings. In some cases, however, unnecessarily detailed descriptions may be omitted. For example, detailed descriptions of known facts and repeated descriptions of essentially identical structures have been left out. This is to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following descriptions serve to ensure the complete understanding of this application by those skilled in the art and are not intended to limit the subject matter specified in the claims.

The “ranges” disclosed in this application are defined in the form of lower and upper bounds. A specific range is defined by selecting a lower and an upper bound, with the selected lower and upper bounds determining the limits of the respective range. The ranges defined by this method may or may not include end values, and any combinations thereof are permissible; that is, any lower bound can be combined with any upper bound to form a range. For example, if ranges of 60 to 120 and 80 to 110 are specified for a particular parameter, then ranges of 60 to 110 and 80 to 120 are also conceivable. If the minimum values of a range are specified as 1 and 2, and the maximum values of the range as 3, 4, and 5, the following ranges can be imagined: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise specified, the range of values "a to b" denotes a shorthand for any combination of real numbers between a and b, where a and b are real numbers. For example, the range of values "0 to 5" means that all real numbers between "0" and "5" are listed in this text, and "0 to 5" is simply a shorthand for this combination of numbers. Furthermore, a parameter expressed as an integer greater than or equal to 2 is equivalent to stating that the parameter is, for example, an integer less than 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

Unless otherwise stated, all embodiments and optional embodiments of this application can be combined with one another, resulting in new technical solutions.

Unless expressly stated otherwise, all technical features and optional technical features of this application can be combined to create new technical solutions.

Unless otherwise specified, all steps in this application may be performed in the order described or in any order, preferably in the order described. For example, procedures comprising steps (a) and (b) may include steps (a) and (b) in the specified order, but may also include steps (b) and (a) in the specified order. For example, the description of the procedure may also include step (c), which means that step (c) may be inserted into the procedure in any order. The procedure may, for example, include steps (a), (b), and (c), but may also include steps (a), (c), and (b), or steps (c), (a), and (b), etc.

The battery cell consists of an electrode assembly and an electrolyte solution. The electrode assembly comprises a positive electrode plate and a negative electrode plate. The negative electrode plate contains a negative active material. A side reaction can occur at the interface between the negative active material and the electrolyte solution, which impairs the charging cycle. As the charging speed of the battery cell increases, the side reaction at the interface of the negative electrodes intensifies, further impairing the charging cycle and hindering rapid charging.

In light of the aforementioned problems, the present application presents a system for battery cells that improves both the cycle life and the fast-charging capability of the battery cells. Specifically, the positive active material comprises lithium-containing phosphates with an olivine structure, while the negative active material consists of graphite particles. The aforementioned material system exhibits excellent cycle life.

During charging, active ions, such as lithium ions, migrate from the positive electrode plate through the electrolyte solution to the negative electrode plate. The electrolyte solution contains carboxylic acid ester solvents, which reduce its viscosity and increase the migration rate of the lithium ions. As the mass concentration of the carboxylic acid solvent increases, the viscosity of the electrolyte solution decreases, the electrical conductivity increases, and the migration rate of the lithium ions can be further increased, thus benefiting fast charging capability. However, with a further increase in the mass concentration of the carboxylic acid solvent, stronger side reactions occur between the solvent and the negative active material, resulting in the production of more gas.

The electrolyte solution also contains linear carbonate solvents. The addition of these solvents allows the electrolyte solution to exhibit relatively high electrical conductivity even with a small addition of carboxylic ester solvents, thereby increasing the migration rate of lithium ions. Furthermore, due to their relatively low mass fraction, the carboxylic ester solvents slow down side reactions and reduce gas formation.

Furthermore, the electrolyte solution also contains additives, including vinylidene carbonate. The reaction potentials of vinylidene carbonate and carboxylic ester solvents are similar, resulting in a competitive reaction between them. Vinylidene carbonate can contribute to the formation of a dense solid electrolyte interface (SEI) layer with organic components on the negative electrode side, making it difficult for carboxylic ester solvents to penetrate the SEI layer to reach the negative active material. This further mitigates side reactions between carboxylic ester solvents and the negative active material and further reduces gas formation. Because the additives are present in appropriate amounts, the membrane impedance on the negative electrode side does not become excessively high, so the fast-charging capability is essentially unaffected.

Therefore, the present application can improve the fast charging capability and cycle stability of the battery cells.

Battery cell

The first aspect of the application introduces a battery cell.

The battery cell comprises an electrode assembly and an electrolyte solution, wherein the electrode assembly includes a positive electrode plate and a negative electrode plate, the positive electrode plate and the negative electrode plate being stacked along the thickness direction of the battery cell; the positive electrode plate comprises a positive current collector and a positive membrane layer arranged on at least one side of the positive current collector. The positive membrane layer comprises a positive active material, wherein the positive active material comprises lithium-containing phosphates with an olivine structure; the negative electrode plate comprises a negative current collector and a negative membrane layer arranged on at least one side of the negative current collector. The negative membrane layer comprises a negative active material, wherein the negative active material comprises graphite particles.

The electrolyte solution contains organic solvents and additives, wherein the organic solvents include carboxylic acid ester solvents and linear carbonate solvents, the mass fraction of the carboxylic acid ester solvents in the electrolyte solution being 10% to 30% and the mass fraction of the linear carbonate solvents being 10% to 50%.

Based on the mass of the electrolyte solution, the mass fraction of the additives is 3% to 9%, containing propane-1,3-sultone at a mass fraction of ≥ 0, ethylene carbonate derivatives at a mass fraction of ≥ 0, and vinylidene carbonate at a mass fraction of > 0. Ethylene carbonate derivatives contain the compounds shown in Formula A.

In formula A, _Q1 , _Q2 , _Q3 and _Q4 each independently contain a hydrogen atom, a halogen atom, a C1-C5 alkyl group or a C1-C5 halogen alkyl group, wherein _Q1 , _Q2 , _Q3 and _Q4 are not simultaneously hydrogen atoms.

The positive active material comprises lithium-containing phosphates with an olivine structure, while the negative active material consists of graphite particles. The aforementioned material system exhibits excellent cycle stability.

During the charging process, active ions, such as lithium ions, migrate from the positive electrode plate through the electrolyte solution to the negative electrode plate. The electrolyte solution contains carboxylic acid ester solvents with a mass fraction of at least 10%, which reduces the viscosity of the electrolyte solution, increases the migration rate of the lithium ions in the electrolyte solution, and improves the fast-charging capability of the battery cells.

As the mass concentration of the carboxylic acid ester solvent increases, the viscosity of the electrolyte solution decreases, the electrical conductivity increases, and the migration rate of lithium ions in the electrolyte solution can be further increased, which benefits fast charging capability. However, with a further increase in the mass concentration of the carboxylic acid ester solvent, stronger side reactions occur between the carboxylic acid ester solvent and the negatively charged active material, resulting in the production of more gas.

The electrolyte solution also contains linear carbonate solvents. The addition of 10% to 50% linear carbonate solvents allows the electrolyte solution to exhibit relatively high electrical conductivity even with a small addition of carboxylic ester solvents, thereby increasing the migration rate of lithium ions. Furthermore, due to their relatively low mass fraction (less than or equal to 30%), the carboxylic ester solvents slow down side reactions on the negative electrode side and reduce gas formation.

Furthermore, the electrolyte solution also contains additives, including vinylidene carbonate. The reaction potentials of vinylidene carbonate and carboxylic ester solvents are similar, resulting in a competitive reaction between them. Vinylidene carbonate can contribute to the formation of a dense solid electrolyte interface (SEI) layer with organic components on the negative electrode side, making it difficult for carboxylic ester solvents to penetrate the SEI layer to reach the negative active material. This further mitigates side reactions between carboxylic ester solvents and the negative active material and further reduces gas formation. Because the additives are present in appropriate amounts, the membrane impedance on the negative electrode side does not become excessively high, so the fast-charging capability is essentially unaffected.

Therefore, the present application can improve the fast charging capability and cycle stability of the battery cells.

[Electrolyte solution]

The battery cell contains an electrolyte solution. During the charging and discharging process of the battery cells, active ions, such as lithium ions, migrate back and forth between the positive and negative electrode plates (intercalation and deintercalation) and are transported by the electrolyte solution between the positive and negative electrode plates.

In some embodiments, the electrical conductivity of the electrolyte solution is 11 mS/cm to 14 mS/cm. For example, the electrical conductivity of the electrolyte solution is 11 mS/cm, 11.5 mS/cm, 12 mS/cm, 12.5 mS/cm, 13 mS/cm, 13.5 mS/cm, 14 mS/cm, or any value within a range between two of these values.

If the electrical conductivity of the electrolyte solution at room temperature (e.g. 25 °C) is within the range mentioned above, the migration rate of the lithium ions in this electrolyte solution is high, which can further reduce the internal resistance of the battery cells, reduce heat generation and improve the fast charging capability of the battery cells.

In the present application, the electrical conductivity of the electrolyte solution at room temperature, for example 25 °C, is the ionic conductivity that can be measured using equipment and methods known in this field, for example according to the industry standard HG-T 4067-2015.

The electrolyte solution consists of an organic solvent and an electrolyte salt.

Organic solvents include carboxylic ester solvents whose mass fraction in the electrolyte solution is between 10% and 30%. For example, the mass fraction of carboxylic ester solvents is 10%, 15%, 20%, 25%, 30%, or any value within a range between these two values. When the mass fraction of carboxylic ester solvents is greater than or equal to 10%, the viscosity of the electrolyte solution system is relatively low, which promotes the migration of lithium ions. When the mass fraction of carboxylic ester solvents is less than or equal to 30%, there are relatively few side reactions between the carboxylic ester solvents and the negative active material, which improves cycle stability.

In some embodiments, carboxylic acid ester solvents may comprise at least one of linear carbonate solvents and cyclic carboxylic acid ester solvents, optionally linear carbonate solvents. Linear carbonate solvents exhibit a lower viscosity, which further increases the migration rate of lithium ions and improves the fast-charging capability of the battery cells.

Due to the lower viscosity and better flowability of linear carbonate solvents, the electrode plates can be saturated more quickly, so that no local lithium plating occurs on the surface of the negative electrode plate during fast charging, which increases the reliability of the battery cells.

For example, carboxylic acid ester solvents include at least one of ethyl acrylate, propyl acetate, ethyl propionate, ethyl formate, propyl formate, ethyl acetate, butyl propionate, optionally ethyl acrylate.

The materials mentioned above have a lower viscosity, which can further improve the fast charging capability of the battery cells.

In the present application, the organic solvent also comprises linear carbonate solvents, wherein the mass fraction of the linear carbonate solvents in the electrolyte solution is 10% to 50%. For example, the mass fraction of linear carbonate solvents in the electrolyte solution is 10%, 15%, 20%, 25%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, or any value within a range between any two of these values.

The above-mentioned linear carbonate solvents with the specified mass fraction can further improve the electrical conductivity of the electrolyte solution at room temperature, which promotes the migration of lithium ions and increases the fast-charging capability of the battery cells.

For example, linear carbonate solvents comprise at least one of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, optionally dimethyl carbonate.

The above-mentioned materials have a relatively low viscosity, which improves the electrical conductivity of the electrolyte solution at room temperature and increases the fast-charging capability of the battery cells.

In some embodiments, the organic solvent also comprises cyclic carbonate solvents, wherein the mass fraction of the cyclic carbonate solvents in the electrolyte solution is between 20% and 50%. For example, the mass fraction of cyclic carbonate solvents in the electrolyte solution is 20%, 25%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, or any value within a range between any two of these values. Cyclic carbonate solvents possess excellent desolventing properties, which enable lithium ions to rapidly detach from the solution structure at the interface between the positive and negative electrodes, thereby increasing the mobility of the lithium ions at the interface and further improving the fast-charging capability of the battery cells.

For example, cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate, one or more of these, optionally ethylene carbonate.

The materials mentioned above have excellent desolvation capabilities, which increases the movement speed of the lithium ions at the interface and thus further improves the fast charging capability of the battery cells.

In the present application, the electrolyte solution also includes additives containing propane-1,3-sultone with a mass content of ≥ 0, ethylene carbonate derivatives with a mass content of ≥ 0 and vinylidene carbonate with a mass content of > 0.

In the present application, the mass content of the additive is 3% to 9%, for example 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9% or any value within a range between any two of these values.

If the mass fraction of the additives is less than 3%, a thinner layer forms on the negative electrode side, which adversely affects the protection of the negative active material. With increasing mass fraction of the additive, film formation on the negative electrode side improves, thus better protecting the negative active material. This reduces the risk of carboxylic acid ester solvents penetrating the SEI layer and entering the negative membrane layer, reduces side reactions on the negative electrode side, decreases gas formation, and improves cycle stability. However, with increasing mass fraction of the additives, the resistance of the SEI layer formed on the negative electrode side increases, which adversely affects fast-charging capability. Therefore, the mass fraction of the additives in the present application is set to 3% to 9%, which improves both the cycle stability and fast-charging capability of the battery cells. Optionally, the mass fraction of the additives can be between 5% and 8%, which further improves the cycle stability and fast-charging capability of the battery cells.

Additives include vinylidene carbonate with a mass content of > 0, i.e., vinylidene carbonate is an obligatory component of the electrolyte solution.

A mass fraction of 0 for propane-1,3-sultone and ethylene carbonate derivatives means that the sum of the mass fraction of propane-1,3-sultone and the mass fraction of ethylene carbonate derivatives is 0. In this case, the additives can consist solely of vinylidene carbonate, with the mass fraction of vinylidene carbonate ranging from 3% to 9%.

Specifically, this means that with a mass content of ethylene carbonate derivatives of 0
either no ethylene carbonate derivatives were added to the freshly prepared electrolyte solution
or the electrolyte solution obtained from disassembled battery cells contains no ethylene carbonate derivatives. This may be because no ethylene carbonate derivatives were added to the freshly produced electrolyte solution, or because only small amounts of ethylene carbonate derivatives were added, but these were involved in the formation of the SEI layer during the formation of the battery cells, so that the mass The content of ethylene carbonate derivatives in the analysis was 0. Optionally, the freshly prepared electrolyte solution may contain ethylene carbonate derivatives.

Furthermore, when certain substances, such as additives, are added to the electrolyte solution, the additive concentration in the battery cell electrolyte solution depends on the battery's formation, life cycle, and storage conditions due to the additives' properties, which involve forming a layer on the surface of the active material. Therefore, differences in additive concentration can occur between freshly prepared electrolyte solution and electrolyte solution from disassembled battery cells. However, experts in this field can determine the approximate concentration of the relevant substances in the fresh electrolyte solution based on the battery cell performance characteristics (e.g., cycle life) and the residual additive content. Similarly, experts in this field can determine the approximate concentration in solutions that are not freshly prepared (i.e., from disassembled battery cells) based on the additive concentration in freshly prepared electrolyte solutions, the performance requirements of the battery cells, and the storage conditions.

Therefore, the additive content mentioned in the technical solution of this application can be both the content of additives that were actively added to the fresh electrolyte solution and the content of additives that was retrospectively determined based on the actual state of the battery.

In some embodiments, the mass fraction of vinylidene carbonate in the electrolyte solution is 0.8% to 7%, for example, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, or 7%, or any value within a range between any two of these values. When the mass fraction of vinylidene carbonate is within the aforementioned range, a dense SEI layer containing organic components can form on the negative electrode side. Furthermore, the resistance of the SEI layer is relatively low, thereby reducing side reactions on the negative electrode side and improving both the cycle life and fast-charging capability of the battery cells. Optionally, vinylidene carbonate can be present in the electrolyte solution at a mass fraction of 2% to 6%.

The additives also contain at least one of propane-1,3-sultone and ethylene carbonate derivatives with a mass content of > 0. The additives may contain propane-1,3-sultone, or the additives may contain ethylene carbonate derivatives, or the additives may contain propane-1,3-sultone and ethylene carbonate derivatives.

In some embodiments, the mass content of propane-1,3-sultone in the electrolyte solution is 0% to 0.5%, for example 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or any value within a range between two of these values.

A mass content of 0 for propane-1,3-sultone means that no propane-1,3-sultone was added to the freshly prepared electrolyte solution, or that the electrolyte solution obtained after disassembling the battery cells contains no propane-1,3-sultone. Typically, the mass content of propane-1,3-sultone in freshly prepared electrolyte solutions is slightly higher than in electrolyte solutions obtained from disassembly, because propane-1,3-sultone is consumed only in small amounts during the film formation process.

Propane-1,3-sultone and vinylidene carbonate both form a dense SEI layer on the negative electrode side and can effectively reduce the risk of penetration of the SEI layer by carboxylic acid ester solvents and a side reaction with the negative active material.

If the mass content of propane-1,3-sulton is greater than 0 and less than or equal to 0.5%, the resistance of the formed SEI layer cannot become too high, thereby reducing the resistance and improving the fast charging capability and cycle stability of the battery cells based on the attenuation of side reactions.

In some embodiments, the mass content of ethylene carbonate derivatives in the electrolyte solution is 0% to 2.55%, for example 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 2.55%, or any value within a range between any two of these values.

Optionally, the freshly prepared electrolyte solution contains ethylene carbonate derivatives, wherein the mass content of the ethylene carbonate derivatives in the freshly prepared electrolyte solution is greater than 0. Ethylene carbonate derivatives preferentially form films. After adding a certain amount of ethylene carbonate derivatives, Due to their high consumption during film formation after disassembly in the battery cells, ethylene carbonate derivatives may no longer be detectable in freshly produced electrolyte solution.

Vinylidene carbonate is continuously involved in the formation of the SEI layer during the battery cell charging cycle and reduces the risk of carboxylic acid ester solvents penetrating the SEI layer. However, the organic content of this SEI layer is relatively high, resulting in a relatively high SEI layer impedance. Ethylene carbonate derivatives, on the other hand, preferentially form a membrane, optimize the composition of the SEI membrane, reduce its resistance, and thus improve the fast-charging capability and cycle stability of the battery cells.

During rapid charging, the three substances mentioned above jointly form a SEI layer. The low content of propane-1,3-sultone strengthens the SEI layer, which is further stabilized by vinylidene carbonate. This reduces the risk of carboxylic acid ester solvents penetrating the SEI layer and improves the cycle life of the battery cells. An appropriate content of ethylene carbonate derivatives reduces film formation resistance, improves fast-charging performance, and the mass fraction of these derivatives is not excessive, thus reducing the risk of decomposition at high temperatures and further enhancing the cycle life of the battery cells. This results in improved fast-charging performance and cycle life of the battery cells.

In the present application, ethylene carbonate derivatives means ethylene carbonate in which at least one hydrogen atom is replaced by one or more substituent groups, wherein the substituent groups can be one, two, three or four.

For example, ethylene carbonate derivatives contain the compounds shown in formula A,

In formula A, _Q1 , _Q2 , _Q3 and _Q4 each contain independently a hydrogen atom, a halogen atom, a C1-C5 alkyl group or a C1-C5 haloalkyl group, wherein _Q1 , _Q2 , _Q3 and _Q4 are not simultaneously hydrogen atoms.

_Q1 , _Q2 , _Q3 and _Q4 are not simultaneously hydrogen atoms, i.e. at least one of _Q1 , _Q2 , _Q3 and _Q4 contains a halogen atom, a C1-C5 alkyl group or a C1-C5 haloalkyl group.

For example, one of the residues Q ₁ , Q ₂ , Q ₃ and Q ₄ contains a halogen atom, a C1-C5 alkyl residue or a C1-C5 haloalkyl residue, while the remaining residues are hydrogen atoms.

For example, at least two of the residues Q ₁ , Q ₂ , Q ₃ and Q ₄ contain halogen atoms, C1-C5 alkyl residues or C1-C5 haloalkyl residues.

For example, at least three of the residues Q ₁ , Q ₂ , Q ₃ and Q ₄ contain halogen atoms, C1-C5 alkyl residues or C1-C5 haloalkyl residues.

For example, Q ₁ , Q ₂ , Q ₃ and Q ₄ each contain halogen atoms, Cl-C5 alkyl groups or C1-C5 halogen alkyl groups independently of each other.

Optionally, at least one of the residues _Q1 , _Q2 , _Q3 , and _Q4 may contain halogen atoms or C1-C5 haloalkyl groups. Halogen atoms include fluorine, bromine, or chlorine atoms, optionally fluorine atoms. C1-C5 haloalkyl groups include C1-C5 fluoroalkyl groups, C1-C5 bromoalkyl groups, or C1-C5 chloroalkyl groups, optionally with fluorine atoms. For example, C1-C5 fluoroalkyl groups include fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, or fluoropentyl.

When ethylene carbonate derivatives contain fluorine atoms, they can form an F- and Li-rich membrane layer on the negative electrode side, which protects the negative active materials while reducing the resistance of the membrane layer, thereby improving the cycle stability and fast-charging capability of the battery cells.

For example, ethylene carbonate derivatives include at least one compound of formula A-1 to formula A-6,

The materials mentioned above can further improve the cycle stability and fast-charging capability of the battery cells.

Optionally, the ethylene carbonate derivatives include at least one of the compounds shown in formula A-1 to formula A-3, and optionally, the ethylene carbonate derivatives include the compound shown in formula A-1.

In some embodiments, the additive also includes lithium salt additives, wherein the lithium salt additives comprise at least one of lithium difluorophosphate, lithium fluorosulfonate, lithium difluorooxalate borate, lithium tetrafluoroborate, and lithium bisoxalate borate. The aforementioned additives improve the properties of the SEI layer on the negative electrode side, thereby increasing the fast-charging capability of the battery cells and improving their cycle life.

In some embodiments, the mass fraction of lithium salt additives in the electrolyte solution is 0.02% to 0.5%, for example, 0.02%, 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, or any value within a range between any two of these values. Lithium salt additives and other additives contribute together to membrane formation and optimize the composition of the SEI membrane. The lithium salt additives contribute to the formation of an inorganic SEI membrane, with the inorganic components increasing the high-temperature and high-pressure stability of the SEI membrane and thus improving the cycle life of the battery cells.

For example, lithium salt additives include lithium difluorophosphate, with the mass content of lithium difluorophosphate in the electrolyte solution being 0.02% to 0.5%.

For example, lithium salt additives include lithium fluorosulfonate, with the mass content of lithium fluorosulfonate in the electrolyte solution being 0.02% to 0.5%.

In some embodiments, the electrolyte salt comprises lithium salts, wherein the lithium salts include lithium hexafluorophosphate _LiPF6 . Optionally, the electrolyte solution also contains lithium salts of lithium fluorosulfonylimide, which improve the cycle stability of the battery cells.

Optionally, the lithium fluorosulfonylimide can comprise one or more of lithium difluorosulfonylimide (LiFSI) and lithium trifluoromethylsulfonylimide (LiTFSI).

In some embodiments, the mass content of lithium salt is 5% to 18%, for example 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17% or 18%, or any value within a range between any two of these values.

In the present application, the type and content of the inorganic components and the lithium salt in the electrolyte solution have a meaning generally known in this field and can be tested using equipment and methods generally known in this field; for example, with reference to the Standard JY/T020-1996 “General rules for ion chromatography “A qualitative or quantitative analysis of the inorganic components/lithium salt of the electrolyte solution can be carried out by means of ion chromatography. In the present application, a newly prepared electrolyte solution can be used as a sample, the free electrolyte solution of a new battery can be used as a sample, or a completely discharged battery cell (discharged to the final charging voltage, so that the state of charge of the battery cell is approximately 0% SOC) can be disassembled, and the free electrolyte solution obtained from the battery cell can be used as a sample, whereupon an examination by means of ion chromatography is carried out.”

In the present application, the type and content of the organic components in the electrolyte solution have a significance generally known in this field and can be tested using equipment and methods generally known in this field; for example, with reference to the Norm GB/T9722-2006 “Chemical reagent - General rules for the gas chromatography “A qualitative or quantitative analysis of the organic components of the electrolyte solution can be carried out using gas chromatography.

[Negative electrode plate]

The negative electrode plate comprises a negative current collector and a negative membrane layer, which is arranged on at least one surface of the negative current collector and contains a negative active material. For example, the negative current collector has two surfaces that are opposite in the direction of its thickness, and the negative membrane layer is arranged on one or both of the two opposite surfaces of the negative current collector.

The maximum charging voltage and the discharge voltage of the battery cells differ depending on the positive active material. For phosphate materials such as lithium iron phosphate, the maximum charging voltage can be, for example, 3.65 V and the discharge voltage 2.0 V. For phosphate materials such as lithium manganese iron phosphate, the maximum charging voltage can be, for example, 4.2 V and the discharge voltage 2.0 V. The following explains the state of the battery cell based on a maximum charging voltage of 3.65 V and a discharge voltage of 2.0 V: In this application, the 100% state of charge (SOC) and the 0% state of charge (SOC) of the battery cell are defined as follows:

The battery cell is charged with a constant current of 0.33C up to the maximum charging voltage, then charged with a constant voltage up to 0.05C, which corresponds to a SOC state of the battery cell of 100%, and subsequently discharged with a constant current of 0.33C up to the discharge voltage, which corresponds to a SOC state of the battery cell of 0%.

In some embodiments, the density of the negative membrane layer in a battery cell in the discharged state (SOC 0%) is 1.30 g/ ^cm³ to 1.52 g/ ^cm³ . For example, the density of the negative membrane layer of a battery cell in the discharged state (0% charge) is 1.30 g/ ^cm³ , 1.32 g/ ^cm³ , 1.35 g/ ^cm³ , 1.40 g/ ^cm³ , 1.45 g/ ^cm³ , 1.50 g/ ^cm³ , 1.52 g/ ^cm³ , or any value within a range between any two of these values.

If the density of the negative membrane layer is within the range mentioned above, the energy density of the battery cells is increased. This is because the negative active material of the negative electrode plate is denser. When arranged in this way, the contact resistance between the particles is lower, which further reduces the resistance of the electrode plate. This reduces heat generation and thus the amount of gas produced by the decomposition of carboxylic acid ester solvents due to heat generation, and improves the cycle stability of the battery cells.

In some embodiments, the one-sided coating weight of the negative membrane layer is 120 mg/1540.25 ^mm² to 180 mg/1540.25 ^mm² . For example, the one-sided coating weight of the negative membrane layer is 120 mg/1540.25 ^mm² , 122 mg/1540.25 ^mm² , 125 mg/1540.25 ^mm² , 128 mg/1540.25 ^mm² , 130 mg/1540.25 ^mm² , 132 mg/1540.25 ^mm² , 135 mg/1540.25 ^mm² , 137 mg/1540.25 ^mm² , 140 mg/1540.25 ^mm² , 145 mg/1540.25 ^mm² , 150 mg/1540.25 ^mm² , 155 mg/1540.25 ^mm² , 160 mg/1540.25 ^mm² . 165 mg/1540.25 ^mm² , 170 mg/1540.25 ^mm² , 175 mg/1540.25 ^mm² , 180 mg/1540.25 ^mm² , or any value within a range between any two of these values. Optionally, the one-sided coating weight of the negative membrane layer is 125 mg/1540.25 ^mm² to 160 mg/1540.25 ^mm² .

If the one-sided coating weight of the negative membrane layer is within the aforementioned range, the heat generation per unit area of the negative electrode plate will not be excessively high, thereby improving the cycle stability of the battery cells.

In the present application, the single-sided coating weight of the negative electrode plate has a meaning known in this field and can be measured using equipment and methods known in this field. With a battery cell in the discharged state (SOC 0%), the negative electrode plate is removed and the compacted density of the negative membrane layer is measured. For example, a single-sided coated negative electrode plate (in the case of double-sided coated electrode plates, the negative coating can first be wiped off one side) is punched into small circles with an area of S1, the weight of which is measured as M1 and the thickness of which is measured as H1. Subsequently, the negative membrane layer of the negative electrode plate (weighed above) is wiped off, the weight of the negative current collector is weighed, recorded as M0, and its thickness H0 is measured. One-sided coating weight of the negative membrane layer = (Weight of the negative electrode plate M1 - Weight of the negative current collector M0) / S1, Thickness of the negative membrane layer = Thickness of the negative electrode plate H1 - Thickness of the negative current collector H0, Compacted density of the negative membrane layer = One-sided coating weight of the negative membrane layer / Thickness of the negative membrane layer.

In the present application, the negative active material comprises a carbon-based material, wherein the carbon-based material includes graphite particles that exhibit high cycle stability and can improve the cycle stability of the battery cells. The positive active material of this application consists mainly of a lithium-containing phosphate system with an olivine structure, while the negative active material consists mainly of a carbon-based material system. By combining both materials, the battery cell exhibits excellent cycle stability.

In some embodiments, the degree of graphitization of the graphite particles is 90% to 94%. For example, the degree of graphitization of graphite particles is 90%, 91%, 92.0%, 92.5%, 93%, 93.5%, 94%, or any value within a range between two of these values.

If the graphitization level of the graphite particles is within the range mentioned above, the graphite particles exhibit excellent electrical conductivity, thereby reducing the heat generation of the negative electrode plate and the battery cells and improving the fast charging capability of the battery cells.

In some embodiments, the volume-related average particle size Dv50 of the graphite particles is 7 µm to 15 µm, for example 7 µm, 7.5 µm, 8 µm, 8.5 µm, 9 µm, 9.5 µm, 9.8 µm, 10 µm, 10.2 µm, 10.5 µm, 10.8 µm, 11 µm, 11.2 µm, 11.5 µm, 11.8 µm, 12 µm, 12.2 µm, 12.5 µm, 12.8 µm, 13 µm, 13.5 µm, 14 µm, 14.5 µm, 15 µm or any value within a range between two of these values.

The volumetric average particle size of the graphite particles is relatively small, which shortens the migration paths of the lithium ions in the solid electrode materials and improves the fast-charging capability of the battery cells. However, under fast-charging conditions, the large active surface area of the small graphite particles leads to violent side reactions with the carboxylic acids. residual solvents in the electrolyte solution. Additives are therefore added to the electrolyte solution that primarily bond to form a film on the negative electrode side, thus providing excellent protection for the positive active material, reducing the risk of side reactions on the negative electrode side, and improving the cycle stability of the battery cells.

In the present application, the volume-averaged particle size Dv50 of a material denotes the particle size that corresponds to 50% of the volume distribution. It can be measured using equipment and methods known in this field, for example by taking the negative active material as a sample and measuring the Dv50 of the particles with a Mastersizer 2000E laser particle measuring device in accordance with the test standard GB/T 19077-2016.

In some embodiments, the graphite particles comprise the graphite particles themselves and a negative coating, wherein the graphite particles themselves comprise secondary particles, the secondary particles comprise several primary particles, the negative coating envelops the surface of the graphite particles themselves, and the negative coating comprises carbon elements. The carbon in the negative coating consists mainly of amorphous carbon. Amorphous carbon is a carbon material in a transitional state with a very low degree of graphitization, resembling an amorphous form (or a structure without a fixed shape and periodic structure). In this application, “amorphous carbon” refers to the product of the carbonization of an organic carbon source.

The graphite particles themselves comprise secondary particles. The migration pathways of lithium ions in the graphite particles are numerous, while those in the primary particles are short, thus increasing the migration rate of the lithium ions. The negative coating exhibits many contact points and defects, providing more sites for lithium ion deintercalation. This improves the conductivity of the negative coating, reduces the internal resistance of the negative electrode plate, minimizes heat generation in the battery cells, and enhances the fast-charging capability and cycle stability of the battery cells.

For example, the graphite particles comprise at least one of artificial graphite and one of natural graphite, with artificial graphite being optional.

Optionally, the thickness of the negative coating can be between 100 nm and 500 nm. For example, the thickness of the negative coating can be 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, or any value within a range between two of these values.

If the thickness of the negative coating is within the range mentioned above, the conductivity of the graphite particles can be further improved, the internal resistance of the negative electrode plate reduced, the heat generation of the battery cells reduced, and the cycle stability of the battery cells improved.

In the present application, the graphite particles can be produced according to a method known in this field. Artificial graphite is used as an example, the production of which is carried out as follows: Artificial graphite and an organic carbon source are provided, mixed and subjected to a carbonization treatment, whereupon a negative coating forms on at least a part of the surface of the artificial graphite particles.

Optionally, organic carbon sources such as coal tar, petroleum bitumen, phenolic resin, or coconut shells can be used. Petroleum bitumen is another optional organic carbon source. Optionally, the softening point of coal tar and petroleum bitumen can be below 250 °C.

Optionally, the carbonization temperature can be between 700 °C and 1800 °C. Optionally, the carbonization temperature can be between 1000 °C and 1300 °C. At a suitable carbonization temperature, organic carbon can be carbonized, and a negative coating of amorphous carbon can be formed on at least part of the surface of the synthetic graphite.

Optionally, the carbonation time can be between 1 and 6 hours.

In some embodiments, the carbon-based material can also contain natural graphite. Specifically, carbon-based materials can contain graphite particles, or carbon-based Materials can contain graphite particles and natural graphite. Optionally, the carbon-based material can consist of graphite particles.

In some embodiments, the negative active material can contain silicon-based material in addition to graphite particles. The introduction of silicon-based material increases the capacity of the negative active material and improves the energy density of the battery cells.

Optionally, the mass fraction of silicon in the silicon-based material, relative to the mass of the negative membrane layer, can range from 0.5% to 10.0%. For example, the mass fraction of the element silicon in the silicon-based material is 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, or any value within a range between any two of these values.

If the mass content of the silicon element in the silicon-based material is within the range mentioned above, the capacity of the negative active material can be increased and the energy density of the battery cells can be improved.

Optionally, the silicon-based material may contain at least one of the following substances: elemental silicon, silicon oxides, silicon-carbon compounds, silicon-nitrogen compounds and silicon alloys.

In some embodiments, the negative active material may, in addition to the carbon-based material mentioned above and the optional silicon-based material, comprise at least one tin-based material and lithium titanate. Tin-based materials may comprise at least one elemental tin, tin oxides, and tin alloys.

The qualitative and quantitative determination of the individual substances or elements in this application can be carried out using equipment and methods suitable for those skilled in the art. The corresponding test procedures may be based on domestic and foreign testing standards as well as domestic and foreign company standards. Furthermore, those skilled in the art may adjust certain test steps/equipment parameters for reasons of test accuracy in order to obtain more precise test results. A single test method may be used for qualitative or quantitative determination, or several test methods may be combined to perform a qualitative or quantitative determination.

For example, this registration can be used in conjunction with the “ General Rules for X-ray Diffraction Analysis” JIS/K0131-1996 An X-ray powder diffraction test is performed on the negative electrode plate or the negative active material, and a qualitative analysis is carried out.

Artificial and natural graphite can be distinguished using SEM profile images obtained with a scanning electron microscope (SEM). SEM profile images of natural graphite show gaps between the flake-like structures, while SEM profile images of artificial graphite are dense and without discernible gaps. A further distinction can be made using XRD spectrograms, which are obtained by X-ray diffraction. The XRD spectrograms of natural graphite show a distinct 2H and 3R phase, while the XRD spectrum of artificial graphite shows only the 2H phase.

The negative membrane layer in the present application comprises at least one membrane layer, wherein a single membrane layer or at least two membrane layers may be used. The negative membrane layer may comprise two, three, four or even more membrane layers. Optionally, the negative membrane layer comprises at least two membrane layers.

When using a single-layer membrane in the negative membrane layer, the active material of the negative membrane layer comprises a carbon-based material and optionally a silicon-based material.

If at least two layers are used in the negative membrane layer, the active material in the negative membrane layer comprises a carbon-based material and optionally a silicon-based material, with the silicon-based material being present in at least one of the two layers or in min It can contain at least two of the two layers. The negative membrane layer can comprise two, three, four, or even more membrane layers.

In some embodiments, the negative membrane layer comprises a first negative membrane layer and a second negative membrane layer, wherein the first negative membrane layer is arranged on the surface of the negative current collector and the carbon material in the first negative membrane layer comprises graphite particles, and the second negative membrane layer is connected to the first negative membrane layer on the side facing away from the negative current collector. The carbon materials in the second negative electrode membrane layer comprise graphite particles, wherein the graphite particles in the first negative electrode membrane layer and the graphite particles in the second negative electrode membrane layer may be identical or different.

The interface between the first negative membrane layer and the second negative membrane layer can be regular or irregular, optionally also irregular.

Optionally, the carbon-based material of the first negative electrode film can also contain natural graphite.

The negative membrane layer consists of at least two membrane layers, the multi-layered coating of which improves the fast-charging capability of the battery cells. In particular, if the first and second negative electrode membrane layers are different, differences can be created in the pores of the negative electrode membrane layer, thereby reducing the impedance of lithium-ion transport and improving the fast-charging capability of the battery cells.

Optionally, both the first negative electrode membrane layer and the second negative electrode membrane layer can contain graphite particles, wherein the average longest diameter of the graphite particles in the first negative electrode membrane layer is greater than or equal to the average longest diameter of the graphite particles in the second negative electrode membrane layer. Furthermore, the average longest diameter of the graphite particles in the first negative electrode membrane layer can be larger than the average longest diameter of the graphite particles in the second negative electrode membrane layer.

The different particle sizes in the first and second negative membrane layers improve the fast-charging capability of the battery cells. Specifically, during fast charging, the overpotential of the second negative membrane layer is typically higher, meaning the bottleneck during fast charging is primarily located in this layer. Since the particle size in the second negative membrane layer is relatively small in the present application, the transport path of the lithium ions in the solid electrode materials can be shortened, the fast-charging capability improved, and lithium plating on the surface of the negative electrode plate reduced.

Optionally, the average longest diameter of the graphite particles of the first negative membrane layer can be between 7 µm and 18 µm. For example, the average longest diameter of the graphite particles in the first negative membrane layer is 7 µm, 7.5 µm, 8 µm, 8.5 µm, 9 µm, 9.5 µm, 10 µm, 10.5 µm, 11 µm, 11.5 µm, 12 µm, 12.5 µm, 13 µm, 13.5 µm, 14 µm, 14.5 µm, 14.6 µm, 15 µm, 15.5 µm, 16 µm, 16.5 µm, 17 µm, 17.5 µm, 18 µm, or any value within a range between any two of these values.

If the average longest diameter of the graphite particles of the first negative membrane layer is within the range mentioned above, the transport path of the lithium ions in the solid electrode materials can be shortened and the fast charging capability improved, and there is less clumping during manufacturing, thereby increasing the stability of the material.

Optionally, the average longest diameter of the graphite particles in the second negative membrane layer can be between 6 µm and 10 µm. For example, the average longest diameter of the graphite particles in the second negative membrane layer can be 6 µm, 6.5 µm, 7 µm, 7.5 µm, 8.0 µm, 8.2 µm, 8.5 µm, 8.8 µm, 9 µm, 9.2 µm, 9.5 µm, 9.8 µm, 10 µm, or any value within a range between any two of these values.

If the average longest diameter of the graphite particles in the second negative membrane layer falls within the aforementioned range, the lithium ion transport path in the solid electrode materials can be shortened, improving fast-charging capability. Furthermore, less clumping occurs during manufacturing, thereby increasing the material's stability. Additionally, combining the negative active material in the second negative membrane layer with the negative active material in the first negative membrane layer, within the aforementioned particle size range, promotes the formation of a porosity gradient between the second and first negative membrane layers. This reduces the impedance of lithium ion transport and further enhances the fast-charging capability of the battery cells.

Optionally, the ratio between the thickness of the second negative membrane layer and the thickness of the negative membrane layer is 0.3 to 0.7. For example, the ratio of the thickness of the second negative membrane layer to the thickness of the negative membrane layer could be 0.3, 0.4, 0.5, 0.6, 0.7, or any value within a range between two of these values. By adjusting the thickness fraction of the first negative membrane layer, the porosity gradient between the upper and lower layers can be further increased, the impedance to lithium-ion transport reduced, and the fast-charging capability of the battery cells improved.

In the present application, the negative electrode plate is cut along its thickness direction to expose the cut surface of the negative membrane layer, which can also be understood as the cross-section of the negative membrane layer along its own thickness direction. By examining the cut surface of the negative membrane layer using scanning electron microscopy (SEM), the longest diameter of the graphite particles is determined. For example, the "longest diameter" of a particle denotes the longest straight line passing through the center of the particle and extending to the outer edge of the particle.

In a cross-section of the negative membrane layer along its thickness direction, the longest diameter of all graphite particles in the cross-section is counted and their average value is calculated as the average longest diameter.

In the cross-section of the negative membrane layer along its thickness direction, the dimensions of the second negative membrane layer and the negative membrane layer are measured, and the percentage of the dimensions of the second negative membrane layer is calculated.

In some embodiments, the negative membrane layer additionally comprises a negative binder comprising at least one of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resins (e.g., polyacrylic acid PAA, polymethyl acrylate PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass fraction of the binder for the negative membrane layer is ≤ 5%, based on the total weight of the negative membrane layer.

In some embodiments, the negative electrode membrane layer may optionally also include a conductive material for the negative electrode. The present application does not impose any specific restrictions regarding the type of conductive material for the negative electrode. For example, the conductive material for the negative electrode may comprise at least one of superconducting carbon, conductive graphite, acetylene carbon black, carbon black, coke carbon black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass fraction of the conductive material for the negative electrode is ≤ 5%, based on the total weight of the negative membrane layer.

In some embodiments, the negative membrane layer may optionally contain additional excipients. Examples of such excipients include thickeners, dispersants such as sodium carboxymethylcellulose (CMC-Na), and PTC thermistors. In some embodiments, the mass fraction of the additional excipients is ≤ 2%, based on the total weight of the negative membrane layer.

In some embodiments, a metal foil or a composite current collector can be used as the negative current collector. Examples of metal foils include foils made of at least one of the following materials: copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector can consist of a polymeric base layer and a metal layer formed on at least one surface of the polymeric base layer. For example, the metal layer can be made of at least one of the following materials: copper, copper alloys, nickel, or nickel alloys. alloys, titanium, titanium alloys, silver, and silver alloys are included. For example, the polymer base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

The negative membrane layer is typically produced by coating the negative current collector with a negative paste, followed by drying and cold pressing. The negative paste is usually prepared by dispersing the negative active material, optional conductive agents, optional binders, and other optional excipients in a solvent, followed by uniform stirring. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

The negative electrode plate does not exclude any additional functional layers besides the negative membrane layer. In some embodiments, the negative electrode plate of the present application also includes, for example, a negative conductive layer arranged between the negative current collector and the negative membrane layer and provided on the surface of the negative current collector. In further embodiments, the negative electrode plate of the present application includes a protective layer covering the surface of the negative electrode membrane layer.

In some embodiments, the negative electrode plate also includes a negative conductive layer located between the negative membrane layer and the negative current collector. This conductive layer improves the conductivity of the negative electrode plate, reduces heat generation from the plate, and consequently, reduces heat generation from the battery cell. This improves the fast-charging capability and cycle stability of the battery cell.

[Positive electrode plate]

The positive electrode plate comprises a positive current collector and a positive membrane layer, which is arranged on at least one surface of the positive current collector and contains a positive active material. For example, the positive current collector has two surfaces that are opposite in the direction of its thickness, and the positive membrane layer is arranged on one or both of the two opposite surfaces of the positive current collector.

In some embodiments, the density of the positive membrane layer of a battery cell in the discharged state (SOC 0%) is 2.3 g/ ^cm³ to 2.6 g/ ^cm³ . For example, the density of the positive membrane layer of a battery cell in the discharged state (SOC 0%) is 2.3 g/ ^cm³ , 2.35 g/ ^cm³ , 2.4 g/ ^cm³ , 2.45 g/ ^cm³ , 2.50 g/ ^cm³ , 2.52 g/ ^cm³ , 2.55 g/ ^cm³ , 2.56 g/ ^cm³ , 2.57 g/ ^cm³ , 2.58 g/ ^cm³ , 2.60 g/ ^cm³ , or any value within a range between any two of these values. Optionally, the compacted density of the positive membrane layer of a battery cell in the discharged state (SOC 0%) is 2.4g/cm ³ to 2.55g/cm ³ .

If the density of the positive membrane layer is within the range mentioned above, the energy density of the battery cells is increased. Because the active material of the positive electrode plate is more densely packed, the contact resistance between the particles is lower, further reducing the resistance of the electrode plate. This reduces heat generation during fast charging and improves the cycle stability and fast-charging capability of the battery cells.

In some embodiments, the one-sided coating weight of the positive membrane layer is 250 mg/1540.25 ^mm² to 330 mg/1540.25 ^mm² , for example 250 mg/1540.25 ^mm² , 260 mg/1540.25 ^mm² , 270 mg/1540.25 ^mm² , 280 mg/1540.25 ^mm² , 290 mg/1540.25 ^mm² , 300 mg/1540.25 ^mm² , 310 mg/1540.25 ^mm² , 320 mg/1540.25 ^mm² , 330 mg/1540.25 ^mm² , or any value within a range between any two of these values. Optionally, the one-sided coating weight of the positive membrane layer is 275 mg/1540.25 ^mm² to 320 mg/1540.25 ^mm² .

If the coating weight of the positive electrode plate is within the range mentioned above, the heat generation per unit area of the positive electrode plate will not be excessively high, thus improving the cycle stability and fast charging capability of the battery cells.

In the present application, the compacted density of the positive membrane layer at a state of charge (SOC) of 0% of the battery cell can be measured using the following method: With a battery cell in a discharged state (SOC 0%), the positive electrode plate is removed and the compacted The density of the positive membrane layer is measured. For example, a single-sided coated positive electrode plate (for double-sided coated electrode plates, the positive coating can first be wiped off one side) is punched into small circles with an area of S1, the weight of which is measured as M1 and the thickness of which is measured as H1. Subsequently, the positive membrane layer of the positive electrode plate (weighed above) is wiped off, the weight of the positive current collector is weighed and recorded as M0, and its thickness H0 is measured. Single-sided coating weight of the positive membrane layer = (weight of the positive electrode plate M1 - weight of the positive current collector M0) / S1, thickness of the positive membrane layer = thickness of the positive electrode plate H1 - thickness of the positive current collector H0, compressed density of the positive membrane layer = single-sided coating weight of the positive membrane layer / thickness of the positive membrane layer.

In some embodiments, the lithium-containing phosphates comprise at least one of the primary particles and secondary particles, wherein the secondary particles comprise several primary particles, i.e., the secondary particles are formed by aggregation of several primary particles and the secondary particles are spherical and/or nearly spherical.

The migration paths of the lithium ions in the primary particles are short, which increases the migration rate of the lithium ions. Furthermore, the secondary particles are spherical and/or nearly spherical, which multiplies the migration paths, further increasing the migration rate of the lithium ions and improving the fast-charging capability of the battery cells.

In some embodiments, the average longest diameter of the first particles is between 300 nm and 800 nm, for example, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, or any value within a range between any two of these values. When the average longest diameter of the primary particles is within the aforementioned range, the migration path of the lithium ions in the solid electrode materials is short, further increasing the migration rate of the lithium ions and improving the fast-charging capability of the battery cells.

In some embodiments, the average particle size of the secondary particles is 5 µm to 15 µm, for example, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, 15 µm, or any value within a range between two of these values. When the average diameter of the secondary particles is within the aforementioned range, the migration path of the lithium ions in the solid electrode materials is short, further increasing the migration rate of the lithium ions and improving the fast-charging capability of the battery cells.

In the present application, the positive electrode plate is cut along its thickness direction to expose the cut surface of the positive membrane layer, which can also be understood as the cross-section of the positive membrane layer along its own thickness direction. By examining the cut surface of the positive membrane layer using scanning electron microscopy (SEM), the average longest diameter of the primary particles and the average particle size of the secondary particles of the lithium-containing phosphates are determined. For example, the "longest diameter" of a particle is defined as the longest straight line passing through the center of the particle and extending to the outer edge of the particle.

In a cross-section of the positive membrane layer along its own thickness direction, the longest diameter of the first lithium-containing phosphate particles is counted, and the average of these longest diameters is calculated. Then, the average of the longest diameters of, for example, 50 of these first lithium-containing phosphate particles is determined as the average longest diameter.

In a cross-section of the positive membrane layer along its own thickness direction, all lithium-containing secondary particles are counted and the average values of the particle size of the secondary particles are calculated as the average particle size of the secondary particles.

In the present application, the lithium-containing phosphate with an olivine structure can consist of phosphate particles or of material obtained by modifying them. For example, the lithium-containing phosphate with an olivine structure can comprise phosphate particles and positive additive elements, wherein the positive additive elements can be located between the phosphate particles, within the phosphate particles, or encapsulating the surface of the phosphate particles. The positive additive elements include at least one of aluminum (Al), vanadium (V), titanium (Ti), and niobium (Nb).

The above-mentioned additional elements for the positive electrode improve the crystal structure stability of the positive active material, increase the compressive strength of lithium-containing phosphates, contribute to improving the compacted density of the positive membrane layer, and increase the energy density and cycle stability of the battery cells.

In some embodiments, the mass content of aluminium in the lithium-containing phosphates is 200 ppm to 2500 ppm, for example 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm, 2000 ppm, 2100 ppm, 2200 ppm, 2300 ppm, 2400 ppm, 2500 ppm or any value within a range between any two of these values. If the mass content of the element aluminium is within the aforementioned range, the compressive strength of lithium-containing phosphates can be improved, which has a positive effect on the compacted density of the positive membrane layer, the energy density of the battery cells and the cycle stability.

In some embodiments, the mass fraction of vanadium in the lithium-containing phosphates is 300 ppm to 2000 ppm, for example, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm, 2000 ppm, or any value within a range between any two of these values. When the mass fraction of the element vanadium is within the aforementioned range, the compacting density of the positive membrane layer is increased, thereby improving the energy density and cycle life of the battery cells.

In some embodiments, the mass fraction of vanadium in the lithium-containing phosphates is 1500 ppm to 3500 ppm, for example, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm, 2000 ppm, 2100 ppm, 2200 ppm, 2300 ppm, 2400 ppm, 2500 ppm, 2600 ppm, 2700 ppm, 2800 ppm, 2900 ppm, 3000 ppm, 3100 ppm, 3200 ppm, 3300 ppm, 3400 ppm, 3500 ppm, or any value within a range between any two of these values. If the mass fraction of titanium is within the aforementioned range, the crystal structure of the positive active material can be further improved and the cycle stability increased.

In some embodiments, the mass content of niobium in the lithium-containing phosphates is 300 ppm to 2000 ppm, for example, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm, 2000 ppm, or any value within a range between any two of these values. If the mass content of the element niobium is within the aforementioned range, the crystal structure of the positive active material can be further improved and the cycle stability increased.

Examples of phosphate particles include, but are not limited to, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate. The materials mentioned above exhibit excellent cycle stability and improve the cycle life of battery cells.

In some embodiments, lithium-containing phosphates comprise compounds of the general formula Lix1Ay1Mea1Mb1P1-c1Xc1Yz1, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.5 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 < b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5, where A comprises at least one of Na, K and Mg; Me comprises at least one of Mn, Fe, Co and Ni; M includes at least one of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La and Ce; X includes at least one of Cl, C, N and P; Y includes at least one of O and F.

Lithium-containing phosphates exhibit excellent cycle stability, which improves the cycle life of battery cells.

For example, phosphate particles comprise one or more of _LiFePO4 , _LiMnPO4 , _LiNiPO4 , and _LiCoPO4 . During charging and discharging, deintercalation and the consumption of active ions such as lithium occur in battery cells. The molarity of lithium in battery cells varies depending on the state of discharge. In the listing of positive active materials _LiFePO4 , _LiMnPO4 , _LiNiPO4 , _LiCoPO4 , etc., the molarity of lithium corresponds to the initial state of the material, i.e., the state before addition. When using positive active materials in battery systems, the molarity of lithium can change after several charging cycles. The positive active materials listed in the present application, _LiFePO4 , _LiMnPO4 , _LiNiPO4 , _LiCoPO4 , etc., include only the theoretical values for the molarity of lithium. Oxygen (O). The release of oxygen from the crystal lattice can change the molarity of oxygen (O), so that the actual molarity of oxygen (O) can fluctuate. All of the above-mentioned cases fall within the scope of protection of the present application.

In the present application, the element content in the positive active material has a meaning known in this field and can be measured using instruments and methods known in this field, for example, according to EPA 6010D-2014 by inductively coupled plasma optical emission spectrometry using plasma atomic emission (ICP-OES, instrument type: Thermo ICAP7400). The battery cell is discharged to a state of charge of 0% SOC, the positive electrode plate is removed, cleaned with DMC and dried, and then calcined at high temperature to remove impurities. Then, 0.4 g of the positive active material is weighed out and mixed with 10 ml (concentration 50%) aqua regia. The sample is then left to stand on a plate heated to 180 °C for 30 minutes. After dissolution on the plate, the volume is adjusted to 100 ml and a quantitative analysis is performed using the standard curve method.

In some embodiments, the positive electrode membrane layer may optionally also comprise a conductive material for the positive electrode. The present application does not impose any specific restrictions regarding the type of conductive material for the positive electrode. For example, the conductive material for the positive electrode may comprise at least one of superconducting carbon, conductive graphite, acetylene carbon black, carbon black, coke carbon black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass fraction of the conductive material for the positive electrode is ≤ 5%, based on the mass of the positive membrane layer.

In some embodiments, the positive membrane layer may optionally also contain a positive binder. The application does not impose any specific restrictions regarding the type of binder for the positive electrode. For example, the positive binder may comprise at least one of the following: polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorinated acrylate resins. In some embodiments, the mass fraction of the binder for the positive electrode is ≤ 5%, based on the mass of the positive membrane layer.

In some embodiments, a metal foil or a composite current collector can be used as the positive current collector. Examples of metal foils include foils made of at least one of the following materials: aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The composite current collector can consist of a polymeric base layer and a metal layer formed on at least one surface of the polymeric base layer. For example, the metal layer can comprise at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymeric base layer can comprise at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

The positive membrane layer is typically produced by applying a positive paste to the positive current collector, drying, and cold pressing. The positive paste is usually prepared by dispersing the positive active material, optional conductive agents, optional binders, and any other components in a solvent, followed by uniform stirring. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP).

The positive electrode plate does not exclude any additional functional layers besides the positive membrane layer. In some embodiments, the positive electrode plate of the present application also includes, for example, a positive conductive layer arranged between the positive current collector and the positive membrane layer and provided on the surface of the positive current collector. In further embodiments, the positive electrode plate of the present application includes a protective layer covering the surface of the positive electrode membrane layer.

[Separator]

In the present application, the separator is arranged between the positive electrode plate and the negative electrode plate in order to isolate the positive electrode plate and the negative electrode plate from each other.

In some embodiments, the porosity of the separator is 20% to 70%, optionally 35% to 60%. For example, the porosity of the separator is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any value within a range between any two of these values.

If the porosity of the separator in the present application is within the above-mentioned range, the migration capability of the lithium ions in the separator can be improved and the internal resistance of the battery cells can be further reduced, thereby reducing heat generation.

In this application, porosity refers to the percentage of the pore volume relative to the total mass of the separator. The porosity can be tested in accordance with standard GB/T 36363-2018 "Polyolefin separators for battery cells". It should be noted that the actual test procedure may deviate slightly from the standard test to obtain more accurate test results, depending on the test equipment, test errors, and to minimize influences on the porosity.

In some embodiments, the separator thickness is 4 µm to 12 µm, optionally 5 µm to 9 µm. For example, the base film thickness is 4 µm, 4.5 µm, 5 µm, 5.5 µm, 6 µm, 6.5 µm, 7 µm, 7.5 µm, 8 µm, 8.5 µm, 9 µm, 9.5 µm, 10 µm, 10.5 µm, 11 µm, 11.5 µm, 12 µm, or any value within a range between any two of these values.

If the thickness of the separator is within the range mentioned above, the migration path of the lithium ions in the separator is shorter, which further reduces the internal resistance of the battery cell and thus reduces heat generation.

In the present application, the separator can be a base film; optionally, the separator can also comprise a functional layer arranged on at least one side of the base film, wherein the functional layer can contain inorganic particles that improve the heat resistance of the separator. Optionally, the functional layer can be arranged on both sides of the base film.

In some embodiments, the base film comprises at least one of the following elements: glass fiber, nonwoven fabric, or polyolefin. The base film can be a single-layer film or a multi-layer composite film; there are no specific restrictions. In the case of a base film made of a multi-layer composite film, the materials of the individual layers can be the same or different; there are no specific restrictions.

Optionally, polyolefin comprises at least one of polyethylene, polypropylene and polyvinylidene fluoride.

In some embodiments, the functional layer may comprise a binder, which optionally includes at least one fluorine-containing binder or a polyacrylic acid binder, for example polyvinylidene fluoride.

In some embodiments, the functional layer may comprise inorganic particles, wherein the inorganic particles may include one or more of the following compounds: silicon dioxide, aluminum oxide, bauxite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. The aforementioned inorganic particles improve the heat resistance of the functional layer.

In the present application, the separator thickness has the significance known in this field and can be measured using methods and equipment known in this field. For example, a newly manufactured separator can be taken as a sample, or a fully discharged battery cell (discharged to the final charging voltage, reducing the battery's state of charge to approximately 0% SOC) can be disassembled so that the separator can be removed from the battery cell, dried, and used as a sample. The separators are cut with an ion beam cutter to create cross-sections. Subsequently, the thickness of the separators and their individual layers is measured using a scanning electron microscope.

In some embodiments, the positive electrode plate, the separator and the negative electrode plate can be manufactured into an electrode assembly by a stacking process.

1 and 2 show a schematic structure diagram of the battery cell.

In some embodiments, the battery cell 7 can comprise a housing 20.

The housing 20 can have various shapes, such as a cylinder or a cuboid. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 has a cylindrical structure, the housing 20 can also be selected as a cylindrical structure. If the electrode assembly 10 has a cuboid structure, the housing 20 can also be selected as a cuboid structure. Optionally, the electrode assembly 10 can also have a cuboid structure.

The housing 20 can be made of various materials, for example, copper, iron, aluminum, stainless steel, aluminum alloys, etc. The present application does not impose any specific restrictions in this regard. Optionally, the inner wall of the housing 20 can also include an insulating layer that separates the housing 20 from the electrode arrangement 10. The material of the insulating layer can be selected from materials commonly used in this field; there are no specific restrictions.

The electrode arrangement 10 housed in the casing 20 can be one or more.

In some embodiments, the housing 20 comprises a base housing 21 and a cover plate 22, wherein the base housing 21 has an opening and the cover plate 22 covers the opening, the base housing 21 accommodating the electrode arrangement 10 and the electrolyte solution.

In some embodiments, the material of the base casing 21 comprises steel, which exhibits high mechanical strength, is not easily deformed, and improves the reliability and cycle stability of the battery cells. Optionally, steel constitutes the highest mass fraction in the base casing 21.

In some embodiments, the length of the battery cell 7 is between 200 mm and 400 mm, for example, 200 mm, 210 mm, 220 mm, 230 mm, 240 mm, 250 mm, 260 mm, 270 mm, 280 mm, 290 mm, 300 mm, 310 mm, 320 mm, 330 mm, 340 mm, 350 mm, 360 mm, 370 mm, 380 mm, 390 mm, 400 mm, or any value within a range between two of these values. If the length of the battery cell 7 is within the aforementioned range, the energy density of the battery cell 7 can be increased. Furthermore, the longitudinal electron transfer path is not too long, which improves the fast-charging capability of the battery cell 7. I Z1, as shown, denotes the length of battery cell 7.

The electrolyte solution exhibits relatively high electrical conductivity, low viscosity, and excellent flow properties. It can rapidly saturate the electrode plate longitudinally, resulting in a relatively uniform reaction along its length. When active ions migrate to the negative electrode plate 12, problems such as lithium plating do not readily occur, thus improving the reliability and cycle stability of the battery cell 7.

In some embodiments, the width of battery cell 7 is between 80 mm and 130 mm, for example, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, or any value within a range between two of these values. If the width of battery cell 7 is within the aforementioned range, the energy density of battery cell 7 can be increased. Furthermore, the longitudinal electron transfer path is not too long, which improves the fast-charging capability of battery cell 7. The in 1 Y1, as shown, denotes the width of battery cell 7.

In some embodiments, the thickness of the battery cell 7 is between 25 mm and 60 mm, for example, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, or any value within a range between two of these values. If the thickness of the battery cell 7 is within the aforementioned range, the internal heat of the battery cell 7 can be dissipated quickly, thereby reducing the risk of electrolyte decomposition due to heat accumulation and improving the cycle life of the battery cell 7. 1 The X1 shown represents the thickness of battery cell 7.

Next, this will be explained using the example of an electrode arrangement 10 in stacked construction.

As in 3 As shown, in an electrode arrangement 10 in the form of a stacked structure, several positive electrode plates 11 and several negative electrode plates 12 are present, wherein the several The positive electrode plates 11 and the multiple negative electrode plates 12 are stacked one above the other in the direction of the thickness X of the battery cell 7. Optionally, the electrode arrangement 10 also includes a separator 13, the separator being located between the positive electrode plate 11 and the negative electrode plate 12.

In some embodiments, the positive electrode plate 11 comprises, as in 4 As shown, at least one positive electrode tab 111 is connected to the positive current collector 112 and extends out of the positive current collector 112 along the longitudinal direction Z of the battery cell 7. This arrangement helps to reduce the space requirement of the electrode tabs and increase the energy density of the battery cells.

For example, at least one positive electrode tab 111 can be arranged on the same side of the positive current collector 112 along the longitudinal direction Z.

Another example is in 5 The figure shows that several positive electrode tabs 111 are provided in the same positive electrode plate 11, wherein the several positive electrode tabs 111 can be arranged on both sides of the positive current collector 112 along the longitudinal direction Z. The positive electrode tab 111 is arranged on both sides of the positive current collector 112, thereby shortening the path of electron movement in the longitudinal direction Z, increasing the velocity of the electrons, and improving the fast-charging capability of the battery cell 7.

As in 5 and 6 As shown, in some embodiments the positive electrode plate 11 fulfills: n*W1/W2 is 0.9 to 1.0;
n denotes the number of all positive electrode tabs 111 that are located on the same side of the positive current collector 112; W1 denotes the average dimension of the positive electrode tab 111 in the lateral direction Y; W2 denotes the dimension of the positive current collector 112 in the lateral direction Y.

For example, n*W1/W2 is equal to 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00 or any value within a range between any two of these values.

If n*W1/W2 fulfills the above-mentioned range, the area of the positive electrode tab 111 for overcurrent is relatively large, which improves the fast charging capability of the battery cell 7.

W1 denotes the average dimension of the positive electrode tab 111 in the lateral direction Y.

If the positive electrode tab 111 has an irregular structure, for example along the longitudinal direction Z, its dimension gradually increases along the lateral direction Y. In this case, the dimension of the positive electrode tab 111 can be measured at several points along the lateral direction Y, and the average dimension of the positive electrode tab 111 along the lateral direction Y can be calculated. Of course, the dimensions of the positive electrode tabs 111 along the lateral direction Y can also be the same at all points; in this case, this value can be used as the average value for the dimensions of these positive electrode tabs 111.

The positive electrode tab 111 can be present once or multiple times, for example n = 1 to 4. If several positive electrode tabs 111 are arranged on the same side of the positive current collector 112, the average dimension of each positive electrode tab 111 can be measured, and the average dimensions can be added and divided by the number of positive electrode tabs 111, resulting in the average dimension of the positive electrode tabs 111.

The positive electrode tab 111 is connected to the positive current collector 112, the positive electrode tab 111 having a first contact point 1111 connected to the positive current collector 112. If n*W1/W2 lies within the range mentioned above, this means that the first contact point 1111 is relatively large along the thickness of the positive electrode tab 111, the contact area between the positive electrode tab 111 and the positive current collector 112 is relatively large, and the overcurrent capability of the positive electrode tab 111 is high, thereby improving the fast-charging capability and the cycle stability of the battery cell 7.

Optionally, the positive electrode tab 111 and the positive current collector 112 can have a one-piece structure, thereby reducing the internal resistance of the positive electrode plate 11 and further improving the cycle stability of the battery cell 7.

As in 7 In other embodiments, at least one positive electrode tab 111 can also be connected to the positive current collector 112 and extend out of the positive current collector 112 along the width direction Y of the battery cell 7.

As in 8 and 9 In some embodiments, the negative electrode plate 12 comprises at least one negative electrode tab 121, wherein at least one negative electrode tab 121 is connected to the negative current collector 122 and extends out of the negative current collector 122 along the longitudinal direction Z of the battery cell 7. Of course, at least one negative electrode tab 121 can also be connected to the negative current collector 122 and extend out of the negative current collector 122 along the lateral direction Y of the battery cell 7.

As in 8 As shown, for example, at least one negative electrode tab 121 can be arranged on the same side of the negative current collector 122 along the longitudinal direction Z.

Another example is in 9 The figure shows that several negative electrode tabs 121 are provided in the same negative electrode plate 12, wherein the several negative electrode tabs 121 can be arranged on both sides of the negative current collector 122 along the longitudinal direction Z. The negative electrode tab 121 is arranged on both sides of the negative current collector 122, thereby shortening the path of electron movement in the longitudinal direction Z, increasing the velocity of the electrons, and improving the fast-charging capability of the battery cell 7.

In some embodiments, the negative electrode plate 12: m*W3/W4 is 0.9 to 1.0;
m denotes the number of all negative electrode tabs 121 that are located on the same side of the negative current collector 122; W3 denotes the average dimension of the negative electrode tab 121 in the lateral direction Y; W4 denotes the dimension of the negative current collector 122 in the lateral direction Y.

For example, m*W3/W4 is equal to 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00 or any value within a range between any two of these values.

If m*W3/W4 meets the above-mentioned range, the area of the negative electrode tab 121 for overcurrent is relatively large, which improves the fast charging capability of the battery cell 7.

W3 denotes the average dimension of the negative electrode tab 121 in the lateral direction Y. The negative electrode tab 121 can be present once or multiple times, for example m = 1 to 4. If several negative electrode tabs 121 are present, the average dimension can be calculated by measuring the dimensions of the individual negative electrode tabs 121 with a micrometer.

The negative electrode tab 121 is connected to the negative current collector 122, the negative electrode tab 121 having a second contact point 1211 that is connected to the negative current collector 122. If m*W3/W4 is within the range mentioned above, this means that the second contact point 1211 is relatively large along the thickness of the negative electrode tab 121, the contact area between the negative electrode tab 121 and the negative current collector 122 is relatively large, and the overcurrent capability of the negative electrode tab 121 is high, thereby improving the fast-charging capability and the cycle stability of the battery cell 7.

Optionally, the negative electrode tab 121 and the negative current collector 122 can have a one-piece structure, thereby reducing the internal resistance of the negative electrode plate 12, further improving the fast charging capability and cycle stability of the battery cell 7.

As in 10 As shown, in some embodiments the battery cell 7 also includes a positive terminal 31 which is arranged on the housing 20, wherein the positive terminal 31 may be arranged on the base housing 21 or on the cover plate 22.

The positive terminal 31 is electrically connected to the positive electrode tab 111. Optionally, the positive terminal 31 and the positive electrode tab 111 can be welded together, using a positive adapter 41. Alternatively, a positive adapter can be omitted, allowing the positive terminal 31 and the positive electrode tab 111 to be welded directly together. This reduces the resistance at the connection point, contributing to a reduction in the overall internal resistance of the battery cell 7.

Optionally, the positive terminal 31 can be arranged on at least one side of the electrode arrangement 10 in the lateral direction Y of the battery cell 7, wherein the positive terminal 31 is connected to the positive electrode tab 111 via the positive adapter 41. This connection via the positive adapter 41 increases the overcurrent capability between the positive terminal 31 and the positive electrode tab 111 and improves the fast-charging capability of the battery cell 7.

Optionally, the thickness of the positive adapter 41 can be between 1.25 mm and 3.00 mm, for example, 1.25 mm, 1.50 mm, 1.75 mm, 2.00 mm, 2.25 mm, 2.50 mm, 2.75 mm, 3.00 mm, or any value within a range between two of these values. The positive adapter 41 is relatively thick and has excellent overcurrent capability, further improving the fast-charging capability of battery cell 7.

For example, the material of the positive adapter 41 can include aluminum, copper, aluminum alloys, copper alloys, etc.

As in 10 and 11 As shown, the positive adapter 41 optionally comprises a first positive adapter section 411 and a second positive adapter section 412, wherein the first positive adapter section 411 is connected to the positive electrode tab 111. The second positive adapter section 412 is connected to the first positive adapter section 411 and projects longitudinally Z from the first positive adapter section 411. The second positive adapter section 412 is connected to the positive terminal 31. The first positive adapter section 411 and the second positive adapter section 412 allow the positive electrode tab 111 to be electrically connected to the positive terminal 31, thereby increasing the overcurrent capability of the positive electrode tab 111 and the positive terminal 31 and improving the fast-charging capability of the battery cell 7.

Optionally, the ratio of the dimension of the first positive adapter section 411 in the lateral direction Y to the width of the battery cell 7 is between 0.2 and 0.5, for example, 0.2, 0.3, 0.4, 0.5, or any value within a range between two of these values. If the ratio of the dimension of the first positive adapter section 411 in the lateral direction Y to the width of the battery cell 7 is within the aforementioned range, the path that electrons travel from the positive electrode tab 111 via the positive adapter 41 to the positive terminal 31 is relatively short, thus improving the fast-charging capability of the battery cell 7. 11 Y2 denotes the dimension of the first positive adapter section 411 in the lateral direction Y, and Y2/Y1 denotes the ratio of the dimension of the first positive adapter section 411 in the lateral direction Y to the width of the battery cell 7.

Optionally, the ratio of the dimension of the second positive adapter section 412 in longitudinal direction Z to the length of the battery cell 7 is between 0.05 and 0.2, for example, 0.05, 0.1, 0.15, 0.2, or any value within a range between two of these values. If the ratio of the dimension of the second positive adapter section 412 in longitudinal direction Z to the length of the battery cell 7 is within the aforementioned range, the path that electrons travel from the positive electrode tab 111 via the positive adapter 41 to the positive terminal 31 is relatively short, thus improving the fast-charging capability of the battery cell 7. 11 Z2 denotes the dimension of the first positive adapter section 411 in longitudinal direction Z, and Z2/Z1 denotes the ratio of the dimension of the second positive adapter section 412 in longitudinal direction Z to the length of the battery cell 7.

In some embodiments, the battery cell 7 also includes a negative terminal 32 which is arranged on the housing 20, wherein the positive terminal 32 may be arranged on the base housing 21 or on the cover plate 22.

The negative terminal 32 is electrically connected to the negative electrode tab 121. Optionally, the negative terminal 32 and the negative electrode tab 121 can be welded together, with the negative terminal 32 and the negative electrode tab 121 being connected via a negative adapter. They can be connected. An adapter can also be omitted, allowing the negative terminal 32 and the negative electrode tab 121 to be welded directly together. This reduces the resistance at the connection point, contributing to a reduction in the overall internal resistance of the battery cell 7.

Optionally, the negative terminal 32 can be arranged on at least one side of the electrode arrangement 10 in the lateral direction Y of the battery cell 7, wherein the negative terminal 32 is connected to the negative electrode tab 121 via the positive adapter 41. The connection via the negative adapter 42 increases the overcurrent load capacity between the negative terminal 32 and the negative electrode tab 121 and improves the fast-charging capability of the battery cell 7.

Optionally, the thickness of the negative adapter 42 can be between 1.25 mm and 3.00 mm, for example, 1.25 mm, 1.50 mm, 1.75 mm, 2.00 mm, 2.25 mm, 2.50 mm, 2.75 mm, 3.00 mm, or any value within a range between two of these values. The negative adapter 42 is relatively thick and has excellent overcurrent capability, further improving the fast-charging capability of battery cell 7.

For example, the material of the negative adapter 42 can include aluminum, copper, aluminum alloys, copper alloys, etc.

How 12 As shown, the negative adapter 42 optionally comprises a first negative adapter section 421 and a second negative adapter section 422, wherein the first negative adapter section 421 is connected to the negative electrode tab 121. The second negative adapter section 422 is connected to the first negative adapter section 421 and projects longitudinally Z from the first negative adapter section 421. The second negative adapter section 422 is connected to the negative terminal 32. Through the first negative adapter section 421 and the second negative adapter section 422, the negative electrode tab 121 can be electrically connected to the negative terminal 32, thereby increasing the overcurrent capability of both and improving the fast-charging capability of the battery cell 7.

Optionally, the ratio of the dimension of the first negative adapter section 421 in the latitudinal direction Y to the width of the battery cell 7 is between 0.2 and 0.5, for example, 0.2, 0.3, 0.4, 0.5, or any value within a range between two of these values. If the ratio of the dimension of the first negative adapter section 421 in the latitudinal direction Y to the width of the battery cell 7 is within the aforementioned range, the path that electrons travel from the negative electrode tab 121 via the negative adapter 42 to the negative terminal 32 is relatively short, thus improving the fast-charging capability of the battery cell 7. 12 Y3 denotes the dimension of the first negative adapter section 421 in the lateral direction Y, and Y3Y1 denotes the ratio of the dimension of the first negative adapter section 421 in the lateral direction Y to the width of the battery cell 7.

Optionally, the ratio of the dimension of the second negative adapter section 422 in longitudinal direction Z to the length of the battery cell 7 is between 0.05 and 0.2, for example, 0.05, 0.1, 0.15, 0.2, or any value within a range between two of these values. If the ratio of the dimension of the second negative adapter section 422 in longitudinal direction Z to the length of the battery cell 7 is within the aforementioned range, the path that electrons travel from the negative electrode tab 121 via the negative adapter 42 to the negative terminal 32 is relatively short, thus improving the fast-charging capability of the battery cell 7. 12 Z3 denotes the dimension of the second negative adapter section 422 in longitudinal direction Z, and Z3Z1 denotes the ratio of the dimension of the second negative adapter section 422 in longitudinal direction Z to the length of the battery cell 7.

As in 13 As shown, the battery cell 7 of the present application can be assembled into a battery module 6, wherein the battery module 6 can contain one or more battery cells 7, the exact number of which can be adjusted depending on the application and capacity of the battery module 6.

If multiple battery cells 7 are present, they can be connected in series, parallel, or a mixed configuration. A mixed configuration means that multiple battery cells 7 are connected both in series and in parallel. Multiple battery cells 7 can be directly connected in series, parallel, or a mixed configuration, and multiple battery cells 7 can then be housed as a single unit in the battery module 6. Of course, multiple battery cells 7 can also initially be connected in series, Battery modules 6 can be connected in parallel or in a mixed configuration to form a battery module 6, and several battery modules 6 can then be connected in series, parallel, or in a mixed configuration to form a whole and housed in the receiving space. Optionally, the battery module 6 can also have a receiving space in which several battery cells 7 are housed.

The battery cells 7 of the battery module 6 can be electrically connected via busbars, allowing the battery cells 7 of the battery module 6 to be connected in parallel, in series, or in a mixed configuration. The busbars can be single or multiple, with each busbar serving to electrically connect at least two battery cells.

As in 14 As shown, in some embodiments the battery module 6 can also be assembled into a battery pack 2, wherein the number of battery modules 6 contained in the battery pack 2 can be adapted depending on the application and capacity of the battery pack. The battery device in this article can be a battery module 6, a battery pack 2, or a battery cell 7, wherein the battery cell 7 represents the smallest unit of the battery device.

The battery pack 2 can contain a battery housing 5 and several battery modules 6 arranged within the battery housing 5. The battery housing 5 comprises a first battery housing part 5a and a second battery housing part 5b, the battery housing 5 having a receiving space 5c, wherein the first battery housing part 5a serves to cover the second battery housing part 5b and form an enclosed space for receiving the battery module 6. Several battery modules 6 can be arranged arbitrarily within the battery housing 5.

The first battery housing part 5a and the second battery housing part 5b are sealed together, and together they define a receiving space 5c for the battery cells. The second battery housing part 5b can be a hollow structure open on one side, wherein the first battery housing part 5a has a plate-like structure and the first battery housing part 5a terminates at the opening side of the second battery housing part 5b to form a battery housing 5 with a receiving space 5c. Alternatively, the first battery housing part 5a and the second battery housing part 5b can each be a hollow structure with one open side, wherein the open side of the first battery housing part 5a terminates at the open side of the second battery housing part 5b to form a battery housing 5 with a receiving space 5c. Naturally, the first battery housing 5a and the second battery housing 5b can have various shapes, such as cylinders, cuboids, etc.

To improve the tightness of the connection between the first battery housing 5a and the second battery housing 5b, a seal, for example sealant or a sealing ring, can be provided between the first battery housing 5a and the second battery housing 5b.

Assuming that the first battery housing part 5a is placed on top of the upper part of the second battery housing part 5b, the first battery housing part 5a can also be referred to as the upper housing cover and the second battery housing part 5b as the lower housing part.

Electrical device

The second aspect of the application concerns an electrical device that includes a battery device as defined in the application, for example, a battery cell, a battery module, or a battery pack. Battery cells, battery modules, or battery packs can be used as a power source for electrical devices or as energy storage devices for electrical devices. Electrical devices can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools. Vehicles can be fuel-powered vehicles, gas-powered vehicles, or new energy vehicles. New energy vehicles include pure electric vehicles, hybrid vehicles, or electric vehicles with range extenders. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, for example, game consoles, electric cars, electric toy boats, and electric toy airplanes, etc. Power tools include power tools for cutting metal, power tools for grinding, power tools for assembly, and power tools for railway construction, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. The embodiment of the application is not subject to any special restrictions with regard to the aforementioned electrical device.

Electrical devices can be equipped with battery cells, battery modules or battery packs, depending on the application requirements.

15 Figure 1 is a schematic structure diagram of an electrical device 1 as an example. The electrical device 1 is a pure electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, etc. To meet the requirements of the electrical device 1 regarding high power and high energy density, battery packs or battery modules can be used.

An electrical device 1 incorporates a battery pack 2, which may be located at the bottom, front end, or rear end of the electrical device 1. The battery pack 2 can be used to power the electrical device 1; for example, it can serve as a power source for the operating system of the electrical device 1, or it can serve as a power source for driving the electrical device 1, replacing all or part of the fuel or gas required to power it.

The electrical device 1 can also include a control unit 3 and a motor 4, wherein the control unit 3 serves to control the battery pack 2 for the power supply of the motor 4, for example the power requirement for starting, navigation and operation of the electrical device 1.

Another example of an electrical device is mobile phones, tablets, laptops, etc. These electrical devices usually need to be light and thin and can be powered by battery cells as a power source.

Designs

The content disclosed in this application is further described with reference to the following embodiments. These embodiments serve only for illustration, as various modifications and changes within the scope of the content disclosed in this application are obvious to those skilled in the art. Unless otherwise stated, all proportions, percentages, and ratios specified in the following embodiments refer to mass, and all reagents used in the embodiments are commercially available or can be prepared by conventional methods and are ready for direct use without further treatment, and the equipment used in the embodiments is commercially available.

Embodiments 1

1. Production of the positive electrode plate

The positive electrode plate comprises a positive current collector and a positive membrane layer, wherein the positive membrane layer is arranged on both sides of the positive current collector and the positive current collector is made of aluminum foil.

The positive membrane layer consists of a membrane layer formed by uniformly applying a positive paste (solvent: N-methylpyrrolidone NMP) to the surface of the positive current collector, followed by drying and cold pressing. The positive membrane layer comprises positive active materials, the binder polyvinylidene fluoride (PVDF), and the conductive agent carbon black acetylene in a mass ratio of 97:2:1.

The positive active material comprises lithium iron phosphate particles and positive additive elements contained within the lithium iron phosphate particles. The positive additive elements include Al, V, Ti, and Nb. The mass fraction of the positive additive elements is 1500 ppm, and the mass ratio of the four elements is 1:1:1:1.

Lithium-containing phosphates comprise primary particles and secondary particles formed by the aggregation of primary particles, with the secondary particles being spherical and/or nearly spherical. In cross-section along the thickness direction of the positive membrane layer, the average longest diameter of the primary particles is 600 nm and the average diameter of the secondary particles is 10 µm.

The one-sided coating weight of the positive membrane layer is 290 mg/1540.25 ^mm² .

2. Production of the negative electrode plate

The negative electrode plate comprises a negative current collector and a negative membrane layer, wherein the negative membrane layer is arranged on both sides of the negative current collector and the negative current collector is made of copper foil.

The negative membrane layer consists of a membrane layer formed by uniformly applying a negative paste (solvent: deionized water) to the surface of the negative current collector, drying and cold pressing.

The first negative membrane layer is arranged on the surface of the negative current collector and consists of negative active materials and conductive agent acetylene carbon black, negative binder butyl rubber, and thickener sodium carboxymethylcellulose in a mass ratio of 96.5:0.5:2:1. The negative active material comprises graphite particles and silicon dioxide, wherein the graphite particles comprise synthetic graphite and a negative coating, the negative coating covering the surface of the synthetic graphite and containing carbon elements, the degree of graphitization of the graphite particles being 92.5% and the volumetric average particle size of the graphite particles being 8.5 µm.

The second negative membrane layer is arranged on the surface of the negative current collector and consists of negative active materials and conductive agent acetylene carbon black, negative binder butyl rubber, and thickener sodium carboxymethylcellulose in a mass ratio of 96.5:0.5:2:1. The negative active material comprises graphite particles and silicon dioxide, wherein the graphite particles comprise synthetic graphite and a negative coating, the negative coating covering the surface of the synthetic graphite and containing carbon element, the mass content of the carbon element in the negative coating being 2%, the degree of graphitization of the graphite particles being 92.5%, and the volumetric average particle size of the graphite particles being 7 µm.

The mass fraction of the silicon element in the negative membrane layer is 0.7%.

In cross-section along the thickness direction of the negative membrane layer, the average longest diameter of the graphite particles of the first negative membrane layer is 11.5 µm, the thickness of the negative coating of the graphite particles in the first negative membrane layer is 200 nm, the average longest diameter of the graphite particles of the second negative membrane layer is 10 µm and the thickness of the negative coating of the graphite particles in the second negative membrane layer is 200 nm.

The one-sided coating weight of the negative membrane layer is 130 mg/1540.25 ^mm² .

3. Separator

The separator consists of a 7 µm thick polyethylene membrane with a porosity of 35%.

4. Preparation of the electrolyte solution

The electrolyte solution consists of organic solvents, lithium salts, and additives. The individual organic solvent components are mixed, the lithium salt and additives are added, and the electrolyte solution is prepared.

Organic solvents include carboxylic acid ester solvents with a mass content of 16.3%, linear carbonate solvents with a mass content of 35.7%, and cyclic carbonate solvents with a mass content of 26.3%.

The mass content of the additives is 6.4% and comprises vinylidene carbonate VC, propane-1,3-sultone and fluoroethylene carbonate FEC in a mass ratio of 4:0.4:2.

The electrolyte solution also contains 0.2% lithium difluorophosphate and 0.1% lithium fluorosulfonate.

Lithium salts include lithium hexafluorophosphate (LiPF ₆ ) with a mass content of 15%.

The electrical conductivity of the electrolyte solution is 12.8 ms/cm.

5. Production of the battery cells

The aforementioned positive electrode plates, separators, and negative electrode plates are stacked on top of each other in the specified order, with the separator positioned between the positive and negative electrode plates, providing insulation. This creates a stacked electrode assembly that is inserted into a housing. The housing is fitted with a positive and a negative terminal. After baking, the electrolyte solution is added, and following vacuum packaging, maturation, forming, and shaping, the battery cell is produced.

The density of the positive membrane layer of the battery cell at 0% SOC is 2.52 g/ ^cm³ , and that of the negative membrane layer at 0% SOC is 1.35 g/ ^cm³ .

The housing is a rectangular aluminum box, with the largest surface of the rectangular structure having a thickness of 0.5 mm.

Design 2-1 to Design 2-5

The battery cells were manufactured in a similar manner to embodiment 1, wherein embodiments 2-1 to 2-4 differ from embodiment 1 in that the mass fraction of the individual solvents was adjusted, and embodiment 2-5 differs in the material of the solvents.

Comparison example 1-1 and comparison example 1-2

The battery cells were manufactured in a similar manner to embodiment 1, differing from embodiment 1 in that the mass content of the individual solvents was adjusted.

Performance test

1. Fast charging test for battery cells

The battery cell is heated to 25 °C
charged with a constant current at 0.33 C from a state of charge (SOC) of 0% to a state of charge (SOC) of 10%;
Charged with constant current at 5.0 C from 10% SOC to 15% SOC;
Charged with a constant current at 4.6C from 15% SOC to 20% SOC;
charged with constant current at 4.2C from 20% SOC to 35% SOC;
charged with constant current at 3.8C from 35% SOC to 45% SOC;
charged with a constant current at 3.6C from 45% SOC to 50% SOC;
Charged with a constant current at 3.4C from 50% SOC to 60% SOC;
charged with constant current at 3.0 C from 60% SOC to 70% SOC;
Charged with constant current at 2.8C from 70% SOC to 75% SOC;
charged with a constant current at 2.4C from 75% SOC to 80% SOC;

The fast charging time of the battery cells from 10% SOC to 80% SOC is recorded.

2. Battery cell cycle life up to 80% SOH

At a temperature of 25 °C, the battery cell is charged with a constant current at 1C until the final charging voltage of 3.65 V is reached. It is then charged with a constant current at 0.05C until the final charging voltage of 3.65 V is reached, and the cell is left to rest for 30 minutes. Next, it is discharged with a constant current at 1C until it reaches 2.5 V and is left to rest for another 30 minutes. This completes one charge and discharge cycle. The charge and discharge cycle described above is repeated until the cycle capacity retention (i.e., Cn/C0 × 100%) reaches 80%. The number of cycles is recorded. The higher the number of cycles, the better the cycle stability of the battery cell.

In the above-mentioned charging and discharging tests of the battery cells, the battery cells can be installed in the battery device to perform the tests using the required charging and discharging strategies controlled by the battery management system.

The test results are listed in Table 1. Table 1 electrolyte solution Battery power Carboxylic acid ester solvents Linear carbonate solvents Cyclic carbonate solvents Electrical conductivity [ms/cm] Fast charging time [min] Cycle count material Mass content [%] material Mass content [%] material Mass content [%] Embodiments 1 EA 16.3 DMC and DEC 35.7 EC 26.3 12.8 20.0 2015 embodiments 2-1 EA 10.0 DMC and DEC 42.0 EC 26.3 11.8 21.7 2224 embodiments 2-2 EA 30.0 DMC and DEC 22.0 EC 26.3 13.8 18.6 1712 embodiments 2-3 EA 28.3 DMC and DEC 10.0 EC 40.0 13.0 19.7 1806 embodiments 2-4 EA 10.0 DMC and DEC 48.3 EC 20.0 12.5 20.4 2008 Models 2-5 EP 16.3 EMC and DEC 35.7 EC 26.3 11.3 22.0 2012 Comparison example 1 1-1 EA 5.0 DMC and DEC 55.0 EC 18.3 10.5 22.5 2252 Comparison example 1 1-2 EA 40.0 DMC and DEC 5.0 EC 33.3 14.5 17.5 1351

In Table 1,
EA stands for ethyl acetate.
EP stands for ethyl propionate.
DMC stands for dimethyl carbonate.
DEC stands for diethyl carbonate; in embodiment 1, embodiment 2-1 to embodiment 2-4, comparative example 1-1 and comparative example 1-2, the mass ratio of DMC and DEC is 1:1.
EMC stands for ethyl methyl carbonate. In embodiments 2-5, the mass ratio of EMC to DEC is 1:1.
EC stands for ethylene carbonate.

The composition of the electrolyte solution of the embodiment and the comparison example was investigated.

The mass fraction of the carboxylic acid ester solvent in the electrolyte solution of comparison example 1-1 is relatively low. Although the introduction of linear carbonate solvents can reduce the viscosity of the electrolyte solution to some extent, the overall viscosity of the electrolyte solution is still relatively high, resulting in high internal resistance and making rapid charging difficult.

The electrolyte solution in comparative example 1-2 also contains a certain proportion of linear carbonates. While this allows for a corresponding reduction in the amount of additives for carboxylic acid ester solvents, the mass fraction of carboxylic acid ester solvents in comparative example 1-2 remains relatively high. This results in lower viscosity and lower resistance of the electrolyte solution, which in turn promotes rapid charging. However, strong side reactions occur between the carboxylic acid ester solvents and the negatively active materials, which impairs cycle stability.

In the present application, adjusting the mass content of the carboxylic acid ester solvent within a suitable range, for example 10% to 30%, in combination with 10% to 50% linear carbonate solvent, reduces the viscosity of the electrolyte solution and the migration rate. The velocity of lithium ions in the electrolyte solution is increased. By using a carboxylic ester solvent in combination with a linear carbonate solvent, the mass fraction of the carboxylic ester solvent is not excessively high, thus mitigating the side reaction between the carboxylic ester solvent and the negative active material. Furthermore, the electrolyte solution contains additives that form an excellent, low-resistance solid electrolyte interface (SEI) layer on the negative electrode side, further reducing side reactions, improving cycle stability, and increasing fast-charging capability.

In embodiments 2-1 to 2-5: The electrical conductivity can be adjusted by modifying the mass fraction of carboxylic acid ester solvents and linear carbonate solvents. Increasing electrical conductivity promotes the migration of lithium ions in the electrolyte solution, thereby improving the fast-charging capability of the battery cells and reducing the charging time.

For example, in embodiment 1, embodiment 2-1, and embodiment 2-2, the electrical conductivity of the electrolyte solution increases with increasing mass concentration of the carboxylic acid ester solvent. This increases the migration rate of the lithium ions in the electrolyte solution, which improves the fast-charging capability of the battery cells and reduces the charging time. However, due to the increased mass concentration of carboxylic acid ester solvents, stronger side reactions occur on the negative electrode side, which impairs the cycle stability to some extent.

In embodiments 2-3 and 2-4: As the mass content of the linear carbonate solvent increases, the electrical conductivity of the electrolyte solution also increases, which can improve the fast charging capability of the battery cells and reduce the charging time.

Carboxylic acid ester solvents are suitable for different materials, linear carbonate solvents are suitable for different materials, for example, in embodiments 2-5 and in embodiment 1, different materials are used for the solvents, which can also improve the fast charging capability and the cycle stability of the battery cells.

embodiment 3-1 to embodiment 3-8

The battery cells are manufactured in a similar manner to embodiment 1, the difference being that either the materials or the mass fractions of the additives are adjusted; corresponding to the adjustment of the mass fraction of the additives and other components, the mass fraction of the organic solvents is adjusted accordingly. For example, if the mass fraction of the additives is increased by 1%, the mass fraction of the organic solvents is decreased by 1%, while the mass ratio of the individual components of the organic solvents remains unchanged, as shown in Table 2.

The electrolyte solutions of embodiments 3 to 8 do not contain lithium difluorophosphate and lithium fluorosulfonate.

The test results are listed in Table 2. Table 2 Additive Battery power VC mass content [%] PS mass content [%] Ethylene carbonate derivatives Mass content [%] Fast charging time [min] Cycle count material Mass content [%] embodiments 3-1 0.8 0.4 FEC 1.80 3.0 19.5 1545 embodiments 3-2 6.6 0.4 FEC 2.00 9.0 21.0 2612 embodiments 3-3 4.0 0.2 FEC 2.00 6.2 19.7 1905 embodiments 3-4 4.0 0.5 FEC 2.00 6.5 20.5 2054 embodiments 3-5 4.0 0.4 FEC 1.00 5.4 19.4 1913 embodiments 3-6 4.0 0.4 FEC 2.52 6.92 20.5 2057 embodiments 3-7 4.0 0.4 DFEC 2.00 6.4 20.3 1944 embodiments 3-8 4.0 0.4 FEC 2.00 6.4 19.8 1952 Comparative example 2-1 0.5 0.4 FEC 1.10 2.0 19.0 1413 Comparative example 2-2 9.6 0.4 FEC 2.00 12.0 22.5 2200

In Table 2,
VC stands for vinylidene carbonate;
PS stands for propane-1,3-sulton.
FEC stands for fluoroethylene carbonate;
DFEC stands for difluoroethylene carbonate.

Comparative example 2-1: The addition of additives to the electrolyte solution is insufficient, for example, the addition of vinylidene carbonate. Although the impedance of the SEI layer on the negative electrode side is relatively low, the protective effect of the SEI layer is relatively poor, so that carboxylic acid ester solvents can easily undergo a side reaction with the negative active material and degrade the charging cycle.

Comparative example 2-2: The addition of additives to the electrolyte solution is too high, for example, the addition of vinylidene carbonate. Vinylidene carbonate can form a dense SEI layer of organic components on the negative electrode side, which mitigates the side reactions between carboxylic acid ester solvents and the negative active material. However, the impedance of the SEI layer is too high, which hinders the rapid migration of lithium ions and leads to a longer charging time for the battery cells.

In contrast, the amount of additive added to the electrolyte solution of the embodiment of the present application is within a suitable range, with a mass content of 3% to 9%, and the reaction potential of the vinylidene carbonate additive and the carboxylic ester solvents is close to each other, so that a competitive reaction with the carboxylic ester solvents occurs. Vinylidene carbonate can participate in the formation of a dense SEI layer on the negative electrode side, thereby preventing carboxylic ester solvents from easily penetrating the SEI layer to the graphite particles. This mitigates the side reactions between the carboxylic ester solvent and the graphite particles and reduces gas formation. Since the additives are present in appropriate amounts, the resistance of the layer formed on the negative electrode side is relatively low, which improves cycle stability and reduces the risk of lithium plating.

Embodiment 3-1 to embodiment 3-8: By regulating the mass content of vinylidene carbonate, propane-1,3-sulton and ethylene carbonate derivatives, a relatively low-resistance SEI membrane can be achieved, thereby improving the fast-charging capability and cycle stability of the battery cells.

In embodiments 1, 3-1, and 3-2: With increasing mass content of vinylidene carbonate, the protective performance on the negative electrode side improves, which benefits cycle stability. However, the impedance of the SEI layer increases, thus extending the fast-charging time.

In embodiments 1, 3-3, and 3-4, the composition of the SEI membrane can be optimized, its protective effect improved, and its cycle life increased by regulating the mass fraction of propane-1,3-sulton. However, this also increases the resistance of the SEI membrane, which may slightly impair the fast-charging capability of the battery cells. Therefore, the mass fraction of propane-1,3-sulton is 0% to 0.5%, optionally 0.2% to 0.5%, to improve both the cycle life and the fast-charging capability of the battery cells.

In embodiments 1, 3-5, and 3-6: By regulating the mass fraction of fluoroethylene carbonate, the composition of the SEI membrane can be optimized with increasing mass fraction of fluoroethylene carbonate, the resistance of the SEI membrane can be reduced, the rapid migration of lithium ions can be promoted, and the fast-charging capability of the battery cells can be improved. While increasing mass fraction of fluoroethylene carbonate improves the protection performance on the negative electrode side, it also increases the resistance of the resulting SE1 membrane, leading to a longer charging time. For this reason, the mass fraction of ethylene carbonate derivatives in the electrolyte solution is limited to 0% to 2.55% to improve both the cycle life of the battery cells and their fast-charging capability.

If the electrolyte solution contains fluoroethylene carbonate, the mass content of vinylidene carbonate can be reduced accordingly, which benefits both the cycle stability of the battery cells and the fast charging capability.

The use of ethylene carbonate derivatives of different materials, such as fluoroethylene carbonate and difluoroethylene carbonate, can effectively improve the cycle stability and fast charging capability of battery cells.

In comparison to embodiments 3-8, embodiment 1 additionally includes lithium fluorosulfonate and lithium difluorophosphate, which further optimizes the composition of the SEI layer on the negative electrode side, improves the protection of the negative electrode side and increases the cycle stability.

embodiment 4-1 and embodiment 4-2

The battery cells were manufactured in a similar manner to embodiment 1, differing from embodiment 1 in that
that in embodiment 4-1 the one-sided coating weight of the positive and negative membrane layer was adjusted.
that in embodiment 4-2 the compressed density of the positive and negative membrane layers was adjusted.

The test results are listed in Table 3. Table 3 Negative electrode plate Positive electrode plate Battery power Negative membrane layer Positive membrane layer Fast charging time [min] Cycle count densified density [g/ ^cm³ ] One-sided coating weight [mg/ ^1540.25mm² ] densified density [g/ ^cm³ ] One-sided coating weight [mg/ ^1540.25mm² ] embodiments4-1 1.35 120 2.52 260 19.0 2115 embodiments4-2 1.52 130 2.60 290 21.5 1924

In contrast to embodiment 1, the one-sided coating weight of the positive and negative membrane layers in embodiment 4-1 is lower, resulting in a relatively low energy density of the battery cells and a shorter migration path of the lithium ions in the positive and negative membrane layers, which promotes faster charging and a shorter charging time. Furthermore, The reduced weight of the coating on one side decreases the total amount of active material involved in the side reaction on the negative electrode side, thus improving cycle stability.

Increasing the density of the positive and negative membrane layers in embodiment 4-2 increases the energy density of the battery cell relatively; however, it also increases the migration resistance of the lithium ions in the positive and negative membrane layers, thus extending the charging time. Furthermore, the cycle life deteriorates slightly due to the increased density, as the total amount of active materials involved in the side reaction on the negative electrode side increases.

5 embodiments

The battery cells were manufactured in a similar manner to embodiment 1, differing from embodiment 1 in that the volume-related average particle size of the graphite particles was adjusted.

6 embodiments

The battery cells were manufactured in a similar manner to embodiment 1, differing from embodiment 1 in that the negative membrane layer of embodiment 6 consists of a single-layer membrane formed by uniformly applying a negative paste (solvent: deionized water) to the surface of the negative current collector, drying and cold pressing.

The negative membrane layer is arranged on the surface of the negative current collector and consists of negative active materials and conductive medium acetylene carbon black, negative binder butyl rubber, and thickener sodium carboxymethylcellulose in a mass ratio of 96.5:0.5:2:1. The negative active material comprises graphite particles and silicon dioxide, wherein the graphite particles comprise synthetic graphite and a negative coating, the negative coating covering the surface of the synthetic graphite. The mass fraction of the carbon element in the negative coating is 2%, the degree of graphitization of the graphite particles is 92.5%, and the volumetric average particle size of the graphite particles is 8.5 µm. The mass fraction of the silicon element in the negative membrane layer is 0.7%.

7 embodiments

The battery cells were manufactured in a similar manner to embodiment 1, differing from embodiment 1 in that the mass content of the silicon element in the negative membrane layer was adjusted to 3.0%.

8 embodiments

The battery cells were manufactured in a similar manner to embodiment 1, differing from embodiment 1 in that the diameter of the particles of lithium-containing phosphates was adjusted.

9 embodiments

The battery cells were manufactured in a similar manner to embodiment 1, differing from embodiment 1 in that no positive additive elements were added to the lithium-containing phosphates.

10 embodiments

The battery cells were manufactured in a similar manner to embodiment 1, differing from embodiment 1 in that the type and mass content of the positive additive elements in lithium-containing phosphates were adapted.

The test results are listed in Table 4. Table 4 Negative electrode plate Positive electrode plate Battery power Graphite particles Dv50[µm] Silicon element mass fraction in the negative membrane layer [%] Lithium-containing phosphates Fast charging time [min] Cycle count Particle diameter positive additional elements Longest diameter of primary particles [nm] Average diameter of secondary particles [µm] Art Mass content [ppm] 5 embodiments 7.5 0.7 600 10 Al, Ti, V, Nb 1500 19.0 1815 6 embodiments 8.5 0.7 600 10 Al, Ti, V, Nb 1500 22.0 2102 7 embodiments 8.5 3.0 600 10 Al, Ti, V, Nb 1500 21.0 1546 8 embodiments 8.5 0.7 300 7 Al, Ti, V, Nb 1500 19.5 1714 9 embodiments 8.5 0.7 600 10 / 0 20.0 1725 10 embodiments 8.5 0.7 600 10 Ti 1000 20.0 1834

The volume-averaged particle size of the graphite particles differs between embodiments 1 and 5. A decreasing volume-averaged particle size of the graphite particles shortens the lithium-ion transport path in solid electrode materials, leading to a reduction in fast-charging time and an improvement in the battery's fast-charging capability. However, the active surface area of the graphite particles can be larger, which may result in increased side reactions and a slight deterioration in the battery's cycle life.

Embodiment 6 uses a single-layer negative membrane. Compared to the single-layer negative membrane, the two-layer membrane of embodiment 1 is more advantageous for creating a porous structure, improves the fast-charging capability of the battery cells, and reduces the fast-charging time. Since the particle size of the graphite particles in embodiment 6 is relatively large, the exposed active surface area can be reduced and the cycle life improved.

The mass fraction of the silicon element in the negative membrane layer of embodiments 1 and 7 differs. With increasing mass fraction of the silicon element, the volume energy density of the battery cell increases; however, the side reactions on the negative electrode side intensify and degrade the charging cycle. Furthermore, due to the repeated expansion of the silicon-based material during the charging and discharging process, the SEI membrane must be constantly regenerated, which can increase the resistance of the SEI membrane and prolong the fast-charging time of the battery cell.

Embodiments 1 and 8 contain lithium phosphates with different particle sizes. With decreasing particle size, the transport path of the lithium ions in the solid electrode materials is shortened, leading to a reduction in fast-charging time and an improvement in the battery's fast-charging capability. However, the active surface area of the lithium phosphates can be larger, which may result in increased side reactions and a slight deterioration in the battery's cycle life.

In contrast to embodiment 9, in which no positive additive elements were added to the lithium-containing phosphates, positive additive elements were added to the lithium-containing phosphates in embodiments 1 and 10, thereby improving the cycle stability of the lithium-containing phosphates and increasing their overall cycle stability. A further improvement was achieved with a corresponding increase in the positive additive elements.

Although illustrative embodiments have been demonstrated and described, it should be clear to those skilled in the art that the embodiments mentioned above are not to be understood as limiting this application and that the embodiments can be changed, replaced and modified without departing from the meaning, principles and scope of this application.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited non-patent literature

• Standard JY/T020-1996 “General rules for ion chromatography [0146]
• Standard GB/T9722-2006 “Chemical reagent - General rules for the gas chromatography [0147]
• General Rules for X-ray Diffraction Analysis” JIS/K0131-1996 [0178]

Claims (38)

A battery cell comprising an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises positive electrode plates and negative electrode plates stacked along the thickness direction of the battery cell. The positive electrode plate comprises a positive current collector and positive membrane layer(s) arranged on at least one side of the positive current collector, the positive membrane layer comprising lithium-containing phosphates with an olivine structure. The negative electrode plate comprises a negative current collector and negative membrane layer(s) arranged on at least one side of the negative current collector, the negative membrane layer comprising graphite particles. The electrolyte solution comprises carboxylic acid ester solvents, linear carbonate solvents, and additives, wherein, based on the mass of the electrolyte solution, the mass fraction of carboxylic acid ester solvents is 10% to 30% and the mass fraction of linear carbonate solvents is 10% to 50%. The mass content of the additives is 3% to 9%, wherein the additives include propane-1,3-sultone with a mass content of ≥ 0, ethylene carbonate derivatives with a mass content of ≥ 0 and vinylidene carbonate with a mass content of > 0, wherein ethylene carbonate derivatives contain the compounds shown in formula A. In formula A, Q1, Q2, Q3 and Q4 each independently contain any one of a hydrogen atom, a halogen atom, a Cl-C5 alkyl group or a Cl-C5 haloalkyl group, where Q1, Q2, Q3 and Q4 are not simultaneously hydrogen atoms. Battery cell after Claim 1 , where the mass content of the additive is 5% to 8%. Battery cell after Claims 1 or 2 , where the mass content of vinylidene carbonate is 0.8% to 7%. Battery cell after Claim 3 , wherein the mass content of vinylidene carbonate is 2% to 6%. Battery cell after one of the Claims 1 until 4 , wherein the mass content of propane-1,3-sultone in the electrolyte solution is 0% to 0.5%. Battery cell after one of the Claims 1 until 5 , wherein the mass content of ethylene carbonate derivatives in the electrolyte solution is 0% to 2.55%. Battery cell according to one of claims 1 to 6, wherein at least one of the residues Q1, Q2, Q3 and Q4 contains halogen atoms or C1-C5 haloalkyl residues. Battery cell after one of the Claims 1 until 7 , wherein ethylene carbonate derivatives comprise at least one compound of formula A-1 to formula A-3, Battery cell after one of the Claims 1 until 8 , where the electrical conductivity of the electrolyte solution is 11 ms/cm to 14 ms/cm. Battery cell after one of the Claims 1 until 9 , wherein carboxylic acid ester solvents comprise at least one of ethyl acrylate, propyl acetate, ethyl propionate, ethyl formate, propyl formate, ethyl acetate, butyl propionate; and/or linear carbonate solvents comprise at least one of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate. Battery cell after one of the Claims 1 until 10 , wherein the electrolyte solution also includes cyclic carbonate solvents, wherein the mass content of the cyclic carbonate solvents in the electrolyte solution is 20% to 50%. Battery cell after Claim 11 , wherein the cyclic carbonate solvents comprise at least one of ethylene carbonate, propylene carbonate and butylene carbonate. Battery cell after one of the Claims 1 until 12 , wherein the electrolyte solution also comprises lithium salt additives, wherein the lithium salt additives comprise at least one of lithium difluorophosphate, lithium fluorosulfonate, lithium difluorooxalate borate, lithium tetrafluoroborate and lithium bisoxalate borate. Battery cell after Claim 13 , wherein the mass content of lithium salt additives in the electrolyte solution is 0.02% to 0.5%. Battery cell after one of the Claims 1 until 14 , wherein the compacted density of the negative membrane layer in a battery cell at a charge level of 0% is 1.30 g/ ^cm³ to 1.52 g/ ^cm³ , and/or, the one-sided coating weight of the negative membrane layer is 120 mg/1540.25 ^mm² to 180 mg/1540.25 ^mm² . Battery cell after one of the Claims 1 until 15 , wherein the graphite particles comprise the graphite particles themselves and a negative coating covering the surface of the graphite particles themselves, wherein the graphite particles themselves comprise secondary particles and the negative coating comprises carbon elements. Battery cell after Claim 16 , wherein the graphite particles comprise at least one of artificial graphite and one of natural graphite. Battery cell after Claims 16 or 17 , wherein the graphitization degree of the graphite particles is 90% to 94%; and/or the volumetric average particle size Dv50 of the graphite particles is 7 µm to 15 µm; and/or the thickness of the negative coating is between 100 nm and 500 nm. Battery cell after one of the Claims 1 until 18 , wherein the negative membrane layer also includes a silicon-based material, wherein the mass content of silicon in the silicon-based material in the negative membrane layer is 0.5% to 10.0%. Battery cell after one of the Claims 1 until 19 , wherein the negative membrane layer comprises: the first negative membrane layer arranged on the surface of the negative current collector; the second negative membrane layer arranged on the side of the first negative membrane layer facing away from the negative current collector, wherein both the first negative membrane layer and the second negative membrane layer contain graphite particles, wherein the average longest diameter of the graphite particles in the first negative membrane layer is greater than or equal to the average longest diameter of the graphite particles in the second negative membrane layer. Battery cell after Claim 20 , wherein the average longest diameter of the graphite particles of the first negative membrane layer is between 7 µm and 18 µm; and/or the average longest diameter of the graphite particles of the second negative membrane layer is between 6 µm and 10 µm. Battery cell after Claims 20 or 21 , where the ratio between the thickness of the second negative membrane layer and the thickness of the negative membrane layer is 0.3 to 0.7. Battery cell after one of the Claims 1 until 22 , wherein the compacted density of the positive membrane layer in a battery cell at 0% charge is 2.3 g/ ^cm³ to 2.6 g/ ^cm³ ; and/or the one-sided coating weight of the positive membrane layer is 250 mg/1540.25 ^mm² to 330 mg/1540.25 ^mm² . Battery cell after one of the Claims 1 until 23 , wherein the lithium-containing phosphates comprise at least one of the primary particles and secondary particles, wherein the secondary particles comprise several primary particles and the secondary particles are spherical and/or nearly spherical. Battery cell after Claim 24 , wherein the average longest diameter of the primary particles is between 300 µm and 800 µm; and/or the average longest diameter of the secondary particles is between 5 µm and 15 µm. Battery cell after one of the Claims 1 until 25 , wherein the lithium-containing phosphates comprise: phosphate particles and positive additive elements contained in the phosphate particles, wherein the positive additive elements include at least one of aluminium, vanadium, titanium and niobium. Battery cell after Claim 26 , wherein the mass content of aluminium in the lithium-containing phosphates is 200 ppm to 2500 ppm; and/or the mass content of vanadium in the lithium-containing phosphates is 300 ppm to 2000 ppm; and/or the mass content of titanium in the lithium-containing phosphates is 1500 ppm to 3500 ppm; and/or the mass content of niobium in the lithium-containing phosphates is 300 ppm to 2000 ppm. Battery cell after Claims 26 or 27 , wherein phosphate particles comprise one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate and lithium cobalt phosphate. Battery cell after one of the Claims 1 until 28 , wherein the lithium-containing phosphates comprise compounds of the general formula Li _x1 Ay ₁ Me _a1 M _b1 P _1-c1 X _c1 Y _z1 , where 0.5 ≤ xl ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.5 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5, where A comprises at least one of Na, K and Mg; Me comprises at least one of Mn, Fe, Co and Ni; M includes at least one of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La and Ce; X includes at least one of Cl, C and N; Y includes at least one of O and F. Battery cell after one of the Claims 1 until 29 , wherein the positive electrode plate comprises at least one positive electrode tab, wherein at least one positive electrode tab is connected to the positive current collector and extends along the longitudinal direction of the battery cell out of the positive current collector; and/or the negative electrode plate comprises at least one negative electrode tab, wherein at least one negative electrode tab is connected to the negative current collector and extends along the longitudinal direction of the battery cell out of the negative current collector. Battery cell after Claim 30 , where the positive electrode plate satisfies: n*W1/W2 is between 0.9 and 1.0; n denotes the number of all positive electrode tabs located on the same side of the positive current collector; W1 denotes the average dimension of the positive electrode tabs along the lateral direction of the battery cell; W2 denotes the dimension of the positive current collector along the lateral direction; and/or the negative electrode plate satisfies: m*W3/W4 is between 0.9 and 1.0; m denotes the number of all negative electrode tabs located on the same side of the negative current collector; W3 denotes the average dimension of the negative electrode tabs along the lateral direction Dimension of the battery cell; W4 denotes the dimension of the negative current collector along the lateral direction. Battery cell after Claims 30 or 31 , wherein the battery cell also comprises a positive terminal and a positive adapter, wherein the positive terminal is arranged on at least one side of the electrode arrangement in the width direction of the battery cell and the positive terminal is connected to the positive electrode tab via the positive adapter; and/or the battery cell also comprises a negative terminal and a negative adapter, wherein the negative terminal is arranged on at least one side of the electrode arrangement in the width direction and the negative terminal is connected to the negative electrode tab via the negative adapter. Battery cell after Claim 32 , wherein the thickness of the positive adapter is 1.25 mm to 3.00 mm; and/or the thickness of the negative adapter is 1.50 mm to 2.50 mm. Battery cell after Claims 32 or 33 , wherein the positive adapter comprises a first positive adapter section and a second positive adapter section, the first positive adapter section being connected to the positive electrode tab. The second positive adapter section is connected to the first positive adapter section and projects longitudinally from the first positive adapter section. The second positive adapter section is connected to the positive terminal; the ratio of the width of the first positive adapter section to the width of the battery cell is between 0.2 and 0.5; and/or the ratio of the length of the second positive adapter section to the length of the battery cell is between 0.05 and 0.2. Battery cell after Claims 32 or 34 , wherein the negative adapter comprises a first negative adapter section and a second negative adapter section, the first negative adapter section being connected to the negative electrode tab; the second negative adapter section being connected to the first negative adapter section and projecting longitudinally from the first negative adapter section; the second negative adapter section being connected to the negative terminal; the ratio of the width of the first negative adapter section to the width of the battery cell being between 0.2 and 0.5; and/or the ratio of the width of the first negative adapter section to the width of the battery cell being between 0.05 and 0.2. Battery cell after one of the Claims 1 until 35 , wherein the length of the battery cell is between 200 mm and 400 mm; and/or the width of the battery cell 7 is between 80 mm and 130 mm, and/or the thickness of the battery cell is between 25 mm and 60 mm. Battery device comprising a battery cell according to one of the Claims 1 until 36 includes. Electrical device comprising a battery device according to Claim 37 includes.