WO2025218148A1 - Dispersing agent, positive electrode slurry, positive electrode sheet, battery and electric device - Google Patents

Abstract

The present application relates to a dispersing agent, a positive electrode slurry, a positive electrode sheet, a battery and an electric device. The dispersing agent comprises an anionic organic chain segment and a non-ionic organic chain segment, wherein the anionic organic chain segment comprises a carbon-carbon main chain and a first group connected to the carbon-carbon main chain; and the non-ionic organic chain segment is connected to the carbon-carbon main chain and comprises a second group, with the polarity of the second group being lower than that of the first group. In the embodiments of the present application, the dispersing agent has excellent dispersing performance and can effectively disperse particles in a positive electrode slurry.

Description

Dispersant, positive electrode slurry, positive electrode sheet, battery and electrical device

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese patent application No. 202410457875.8 filed on April 16, 2024, entitled “Dispersant, positive electrode slurry, positive electrode sheet, battery and electrical device,” the entire contents of which are incorporated herein by reference.

Technical Field

The present application relates to a dispersant, a positive electrode slurry, a positive electrode plate, a battery and an electrical device.

Background Art

Batteries have high capacity and other characteristics, so they are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes and power tools, etc.

The battery includes a positive electrode plate, which is formed by drying a positive electrode slurry arranged on a positive electrode current collector. However, the positive electrode active particles in the positive electrode slurry are prone to agglomeration, resulting in poor performance uniformity and leveling of the positive electrode slurry, thereby affecting the performance of the positive electrode plate and further affecting the performance of the battery.

Summary of the Invention

The present application provides a dispersant, a positive electrode slurry, a positive electrode plate, a battery and an electrical device. The dispersant in the embodiment of the present application has excellent dispersibility and can effectively disperse the particles in the positive electrode slurry.

In the first aspect, an embodiment of the present application proposes a dispersant, which includes an anionic organic segment and a non-ionic organic segment, the anionic organic segment includes a carbon-carbon main chain and a first group connected to the carbon-carbon main chain, the non-ionic organic segment is connected to the carbon-carbon main chain, and the non-ionic organic segment includes a second group, the polarity of the second group is less than that of the first group.

Thus, the embodiments of the present application provide anionic organic segments and nonionic organic segments in the same compound, wherein one segment plays a role of anchoring to the surface of the positive electrode active particles while the other plays a dispersing role. This can anchor the dispersant to the surface of the positive electrode active particles while also effectively dispersing the positive electrode active particles, thereby making the performance of the positive electrode slurry stable, uniform, and with good leveling. Moreover, the dispersant can also effectively disperse additives such as conductive agents and binders, making the performance of the positive electrode slurry more uniform and further improving the leveling property on the positive electrode current collector.

In some embodiments, the anionic organic segment comprises a segment of Formula I,

R ₁ , R ₂ and R ₃ each independently include a hydrogen atom, a C1 to C3 alkyl group;

R ₄ includes a single bond or a C1 to C3 alkylene group;

R ₅ is a first group, R ₅ includes carboxylic acid or its anion, sulfonic acid or its anion, phosphoric acid or its anion, pyrrolidone or its anion, amide or its anion, or carboxylate group;

n represents the degree of polymerization, and n is greater than or equal to 2.

In some embodiments, R ₁ , R ₂ and R ₃ each independently comprise a hydrogen atom or a methyl group; and/or

R ₄ includes a single bond or a methylene group.

Therefore, in the embodiment of the present application, the anionic organic chain segment can interact with the positive electrode active particles through hydrogen bonds and bind to the surface of the positive electrode active particles; the anionic organic chain segment can also disperse the particles through electrostatic repulsion.

In some embodiments, the segment represented by Formula I includes one or more of the segments represented by Formula I-1 to the segments represented by Formula I-14.

In some embodiments, the second group includes one or more of an ether bond, a phenyl group, and a hydroxyl group. The second group has relatively weak polarity and a relatively more uniform charge distribution; the second group can bind to the surface of the positive electrode active particles through the interaction with the non-polar groups in the positive electrode active particles.

In some embodiments, the nonionic organic segments containing ether bonds include one or more of polyethylene glycol segments, polyglycerol segments, and polyoxypropylene segments. The nonionic organic segments containing ether bonds are primarily linear segments, comprising a carbon-oxygen backbone. The carbon-oxygen backbone has relatively weak polarity and readily interacts with nonpolar groups on the surface of the positive electrode active particles. Furthermore, the linear segments are less susceptible to entanglement, allowing their secondary groups to effectively function and provide excellent dispersion.

In some embodiments, the phenyl-containing nonionic organic chain segments include one or more of polystyrene and polyaniline segments. These nonionic organic segments are primarily linear segments, comprising a carbon-carbon backbone and phenyl groups attached to the carbon-carbon backbone. The phenyl groups have relatively low polarity and readily interact with nonpolar groups on the surface of the positive electrode active particles. Furthermore, the linear segments are less susceptible to entanglement, effectively enabling the secondary groups to function and providing excellent dispersion.

In some embodiments, the hydroxyl-containing nonionic organic chain segment comprises a polyenol chain segment. These nonionic organic chains are primarily linear, making them susceptible to interaction with the nonpolar groups on the surface of the positive electrode active particles. Furthermore, these linear chains are less susceptible to entanglement, effectively enabling their secondary groups to function and providing excellent dispersion.

In some embodiments, the polyenol segment includes one or more of a polyvinyl alcohol segment and a polypropylene alcohol segment.

In some embodiments, the nonionic organic segment includes one or more of a polyethylene glycol segment and a polystyrene segment. The nonionic organic segment is combined with the anionic organic segment to improve the dispersing performance of the dispersant.

In some embodiments, the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the nonionic organic segment is 0.4 to 2.3. When the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the nonionic organic segment is within the above range, the dispersant can be effectively anchored to the surface of the positive electrode active particles and the particles can be effectively dispersed.

In some embodiments, the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the nonionic organic segment is 0.7 to 1.5. When the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the nonionic organic segment is within the above range, the particles can be further effectively dispersed.

In some embodiments, the number average molecular weight of the dispersant is 1000 to 20000. When the number average molecular weight of the dispersant is within the above range, the dispersant has excellent suspending ability and can effectively disperse particles; the dispersant also has relatively excellent steric hindrance and can effectively disperse particles.

In some embodiments, the number average molecular weight of the dispersant is 2000 to 5000. When the number average molecular weight of the dispersant is within the above range, the particles can be effectively dispersed.

In a second aspect, an embodiment of the present application further provides a positive electrode slurry, comprising a dispersant and positive electrode active particles as in any embodiment of the first aspect of the present application.

Therefore, the embodiment of the present application can anchor the dispersant on the surface of the positive electrode active particles while playing a role in well dispersing the positive electrode active particles by setting anionic organic segments and nonionic organic segments in the same compound, thereby making the performance of the positive electrode slurry uniform and the leveling property better.

In some embodiments, the dispersant content is 0.3% to 1.1% by weight based on the solid content of the positive electrode slurry. Within this range, the dispersant can substantially cover all of the positive electrode active particles, effectively dispersing the positive electrode active particles. Furthermore, the dispersant's molecular chains are substantially prevented from entangled with each other, reducing the risk of flocculation in the positive electrode slurry.

In some embodiments, the positive electrode active particles include olivine-type phosphate active materials. Olivine-type phosphate active materials are prone to agglomeration and the like. When used in combination with the above-mentioned dispersant, the dispersion effect of the olivine-type phosphate active materials can be effectively improved.

In some embodiments, the olivine-type phosphate active material includes phosphate particles and a carbon coating layer coated on the surface of the phosphate particles. When the carbon coating layer is provided on the surface, it can improve the conductivity of the phosphate particles and improve the Good at making full use of capacity.

In some embodiments, the mass content of the carbon coating layer is 3% to 3.6% based on the total mass of the olivine phosphate active material. In the case of complete or incomplete coating, the dispersant can have an excellent dispersion effect on the particles and has high compatibility.

In some embodiments, the olivine-type phosphate active material includes a compound of _the general formula _{LixAyMeaMbP1 -cXcYz ,} wherein _0≤x≤1.3 , 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; _A includes one or more of Na, K, and _Mg ; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more 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 one or more of S, Si, Cl, B, C, and N; and Y includes one or more of O and F.

In some embodiments, the volume average particle size D _v 50 of the positive electrode active particles is 0.5 μm to 10 μm. When the particle size of the olivine phosphate active material is within the above range, the above dispersant can be used to effectively improve the dispersion effect of the olivine phosphate active material.

In some embodiments, the volume average particle size D _v 50 of the positive electrode active particles is 0.5 μm to 2 μm. When the particle size of the olivine phosphate active material is within the above range, the above dispersant can be used to effectively improve the dispersion effect of the olivine phosphate active material.

In a third aspect, an embodiment of the present application further proposes a positive electrode plate, which includes a positive electrode collector and a positive electrode film layer arranged on at least one side of the positive electrode collector, and the positive electrode film layer includes a dispersant and positive electrode active particles as in any embodiment of the first aspect of the present application.

In some embodiments, the mass content of the dispersant is 0.3% to 1.1% based on the mass of the positive electrode film. When the mass content of the dispersant is within this range, the dispersant can substantially cover all the positive electrode active particles, thereby effectively dispersing the positive electrode active particles; the molecular chains of the dispersant are substantially prevented from entangled with each other, reducing the risk of flocculation in the positive electrode slurry and ensuring uniform performance of the positive electrode film formed from the positive electrode slurry.

In some embodiments, the positive electrode active particles include olivine-type phosphate active materials. Olivine-type phosphate active materials are prone to agglomeration and the like. When used in combination with the above-mentioned dispersant, the dispersion effect of the olivine-type phosphate active materials can be effectively improved.

In a fourth aspect, an embodiment of the present application further proposes a battery, which includes the positive electrode sheet of any embodiment of the third aspect of the present application.

In a fifth aspect, an embodiment of the present application further proposes an electrical device comprising a battery cell as in any embodiment of the fourth aspect of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

FIG1 is a schematic diagram of a battery cell according to an embodiment of the present application.

FIG. 2 is an exploded schematic diagram of an embodiment of the battery cell of FIG. 1 .

FIG3 is a schematic diagram of an embodiment of a battery module of the present application.

FIG4 is a schematic diagram of an embodiment of a battery pack of the present application.

FIG. 5 is an exploded schematic diagram of the embodiment of the battery pack shown in FIG. 4 .

FIG6 is a schematic diagram of an embodiment of an electric device including the battery cell of the present application as a power source.

The drawings are not necessarily drawn to scale.

The following are the descriptions of the reference numerals:
1. Battery pack; 2. Upper box; 3. Lower box; 4. Battery module;
5. Battery cell; 51. Housing; 52. Electrode assembly;
53. Cover plate;
6. Electrical equipment.

DETAILED DESCRIPTION

Below, with appropriate reference to the accompanying drawings, the embodiments of the dispersant, positive electrode slurry, positive electrode sheet, battery and electrical device of the present application are described in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

" range " disclosed in the application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " a-b " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), which indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may further include step (c), which indicates that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

The battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. The separator is located between the positive electrode sheet and the negative electrode sheet to isolate the positive electrode sheet from the negative electrode sheet.

The positive electrode sheet is formed by coating the positive electrode slurry on the positive electrode collector and drying it. The positive electrode slurry includes positive electrode active materials, conductive agents, binders and solvents. The positive electrode active materials in the positive electrode slurry may agglomerate, resulting in poor dispersion of the positive electrode active materials in the positive electrode slurry, uneven performance of the positive electrode slurry, and poor leveling of the positive electrode slurry on the positive electrode collector. Poor quality.

In view of this, the embodiment of the present application adds a dispersant to the positive electrode slurry, and the dispersant sets anionic organic segments and non-ionic organic segments in the same compound, which can anchor the dispersant on the surface of the positive electrode active particles while playing a role in well dispersing the positive electrode active particles, thereby making the performance of the positive electrode slurry stable, uniform, and with good leveling properties.

dispersants

The embodiments of the present application provide a dispersant.

The dispersant includes an anionic organic segment and a nonionic organic segment, the anionic organic segment includes a carbon-carbon main chain and a first group connected to the carbon-carbon main chain, the nonionic organic segment is connected to the carbon-carbon main chain, and the nonionic organic segment includes a second group, and the polarity of the second group is less than that of the first group.

The first group is more polar and can be considered a polar group. The second group is less polar and can include a weakly polar group or a non-polar group. The polarity of a group can be found in an organic chemistry handbook or instruction manual.

When the dispersant is applied to the positive electrode slurry, when the polarity of the surface of the positive electrode active particles is relatively strong, the first group in the anionic organic chain segment can interact with the positive electrode active particles through hydrogen bonding; the surface of the positive electrode active particles is easy to adsorb charged particles due to its strong polarity, which can further enhance the binding effect with the anionic organic chain segment, so that the anionic organic chain segment is anchored on the surface of the positive electrode active particles; since the anionic organic segment and the nonionic organic segment are in the same compound, along with the anionic organic segment binding to the surface of the positive electrode active particles, the nonionic organic segment will be distributed outside the positive electrode active particles together, and the nonionic organic segment can form a steric hindrance between the particles, reduce the agglomeration between the particles, and help improve the dispersion performance of the particles, so that the performance of the positive electrode slurry is uniform and the leveling is good.

When the dispersant is applied to the positive electrode slurry, in the case that the surface of the positive electrode active particles mainly includes non-polar groups, the non-ionic organic segment includes a second group, and the polarity of the second group is weaker, and it is easier to bind to the surface of the positive electrode active particles, so that the non-ionic organic segment is anchored on the surface of the positive electrode active particles; since the non-ionic organic segment and the anionic organic segment are in the same compound, as the non-ionic organic segment is bound to the surface of the positive electrode active particles, the anionic organic segment will also be distributed outside the positive electrode active material to form a negative layer. The particles repel each other through electrostatic repulsion, which reduces the attraction between the particles, which is beneficial to improving the dispersion performance of the particles, making the performance of the positive electrode slurry uniform and the leveling property better.

When the surface of the positive electrode active particles is mainly polar and supplemented by non-polarity, the polar region is anchored to the surface of the positive electrode active particles through anionic organic chain segments, and the non-ionic organic chain segments play a role in dispersing the particles through steric hindrance; the non-polar region is anchored to the surface of the positive electrode active particles through non-ionic organic chain segments, and the anionic organic chain segments play a role in dispersing the particles through electrostatic repulsion. The dispersant is easily evenly distributed on the periphery of the positive electrode active particles, and has an excellent dispersing effect on the positive electrode active particles.

When the surface of the positive electrode active particles is mainly non-polar and supplemented by polarity, the non-polar region is anchored to the surface of the positive electrode active particles through the non-ionic organic chain segments, and the anionic organic chain segments play a role in dispersing the particles through electrostatic repulsion; the polar region is partially anchored to the surface of the positive electrode active particles through the anionic organic chain segments, and the non-ionic organic chain segments play a role in dispersing the particles through steric hindrance. The dispersant is easily evenly distributed on the periphery of the positive electrode active particles, and has an excellent dispersing effect on the positive electrode active particles.

In the related art, the dispersant may include two types of polymers, which are mixed physically. For example, one type includes anionic polymers and the other type includes nonionic polymers. Although the above two types of polymers can also play a dispersing role, when one of the polymers occupies the particle surface, it will interfere with the other type of polymer, making the other type of polymer The compound cannot achieve a good dispersion effect, resulting in problems such as agglomeration in the positive electrode slurry.

In the embodiments of the present application, the anionic organic segment and the nonionic organic segment can be located at either end of the molecular chain, with one segment serving as an anchor to the surface of the positive electrode active particles while the other serves as a dispersant. Thus, by providing the anionic organic segment and the nonionic organic segment in the same compound, the embodiments of the present application can simultaneously anchor the dispersant to the surface of the positive electrode active particles while effectively dispersing the positive electrode active particles, thereby ensuring stable and uniform performance and good leveling of the positive electrode slurry.

Moreover, the dispersant can also effectively disperse conductive agents, binders and other additives, making the performance of the positive electrode slurry more uniform and further improving the leveling property on the positive electrode current collector.

[Anionic organic segment]

The anionic organic chain segments can interact with the positive electrode active particles through hydrogen bonds and bind to the surface of the positive electrode active particles; the anionic organic chain segments can also disperse the particles through electrostatic repulsion.

In some embodiments, the anionic organic segment comprises a segment of Formula I,

R ₁ , R ₂ and R ₃ each independently include a hydrogen atom, a C1 to C3 alkyl group;

R ₄ includes a single bond or a C1 to C3 alkylene group;

_R5 is a first group, _R5 includes carboxylic acid or its anion, sulfonic acid or its anion, phosphoric acid or its anion, pyrrolidone or its anion, amide or its anion, or carboxylate group; corresponding to the anion, the cation in the system may include one or more of lithium ion, sodium ion, potassium ion, calcium ion, etc.;

n represents the number of structural units in the segment represented by formula I, or the degree of polymerization of the segment represented by formula I, and n is any positive integer greater than or equal to 2.

The C1 to C3 alkyl group may include a methyl group, an ethyl group, or a propyl group. Alternatively, _R1 , _R2 , and _R3 may each independently include a hydrogen atom or a methyl group. Furthermore, _R1 , _R2 , and _R3 may each independently include a hydrogen atom. The shorter the branch chain length, the higher the proportion of the first group R5, and the stronger the binding between the first group and the positive electrode active particles.

The C1 to C3 alkylene groups may include methylene, ethylene, or propylene. Alternatively, _R4 may include a single bond or a methylene group. The shorter the branch length, the higher the proportion of the first group _R5 , and the stronger the binding effect between the first group and the positive electrode active particles.

n represents the number of structural units in the segment represented by formula I,

Illustratively, the segment represented by Formula I includes one or more of the segments represented by Formula I-1 to the segments represented by Formula I-14.

[Nonionic organic segment]

The non-ionic organic chain segment can interact with the positive electrode active particles through the second group and bind to the surface of the positive electrode active particles; the non-ionic organic chain segment can also play a role in dispersing particles through steric hindrance.

In some embodiments, the degree of polymerization (m) of the nonionic organic segment may be greater than or equal to 2. The degree of polymerization refers to the number of repeating units in the nonionic organic segment. In other words, the nonionic organic segment is a polymer organic segment.

In some embodiments, the second group includes one or more of an ether bond, a phenyl group, and a hydroxyl group. The second group has relatively weak polarity and a relatively more uniform charge distribution; the second group can bind to the surface of the positive electrode active particles through the interaction with the non-polar groups in the positive electrode active particles.

The non-ionic organic chain segments containing ether bonds are mainly linear segments, which include a carbon-oxygen main chain. The polarity of the carbon-oxygen main chain is relatively weak, and it is easy to react with the non-polar groups on the surface of the positive electrode active particles; and the linear segments are not easy to entangle, can effectively play the role of their second group, and have an excellent dispersing effect.

Illustratively, the nonionic organic segment containing an ether bond includes one or more of a polyethylene glycol segment, a polyglycerol segment, and a polyoxypropylene segment.

In some embodiments, the phenyl-containing nonionic organic chain segments include one or more of polystyrene and polyaniline segments. These nonionic organic chain segments are primarily linear segments, comprising a carbon-carbon backbone and aromatic groups, such as phenyl groups, attached to the carbon-carbon backbone. Phenyl groups have relatively low polarity and readily interact with nonpolar groups on the surface of the positive electrode active particles. Furthermore, linear segments are less prone to entanglement, effectively enabling the secondary groups to function and providing excellent dispersion.

In some embodiments, the hydroxyl-containing nonionic organic chain segment comprises a polyenol chain segment. These nonionic organic chains are primarily linear, making them susceptible to interaction with the nonpolar groups on the surface of the positive electrode active particles. Furthermore, these linear chains are less susceptible to entanglement, effectively enabling their secondary groups to function and providing excellent dispersion.

Illustratively, the polyenol segment includes one or more of a polyvinyl alcohol segment and a polypropylene alcohol segment.

In some embodiments, the nonionic organic segment includes one or more of a polyethylene glycol segment and a polystyrene segment. Optionally, the nonionic organic segment includes a polyethylene glycol segment. The combination of the nonionic organic segment and the anionic organic segment further enhances the dispersing properties of the dispersant.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include a segment shown in Formula I-1, and the nonionic organic segment includes a polyethylene glycol segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include a segment shown in Formula I-2, and the nonionic organic segment includes a polyethylene glycol segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include the segment shown in I-3, and the nonionic organic segment includes a polyethylene glycol segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include the segment shown in I-5, and the nonionic organic segment includes a polyethylene glycol segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include the segment shown in I-7, and the nonionic organic segment includes a polyethylene glycol segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include the segment shown in I-11, and the nonionic organic segment includes a polyethylene glycol segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include a segment shown in Formula I-1, and the nonionic organic segment includes a polyoxypropylene segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include a segment shown in Formula I-2, and the nonionic organic segment includes a polyoxypropylene segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include a segment shown in Formula I-1, and the nonionic organic segment includes a polystyrene segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include a segment shown in Formula I-1, and the nonionic organic segment includes a polyglycerol segment.

As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant may include a segment shown in Formula I-1, and the nonionic organic segment includes a polyvinyl alcohol segment.

In some embodiments, the ratio of the degree of polymerization n of the anionic organic segment to the degree of polymerization m of the nonionic organic segment is 0.4 to 2.3, and can be optionally 0.7 to 1.5, for example, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, or a range consisting of any two of the above values.

When the ratio of the polymerization degree n of the anionic organic segment to the polymerization degree m of the nonionic organic segment is within the above range, the dispersant can be effectively anchored on the surface of the positive electrode active particles and the particles can be effectively dispersed.

In some embodiments, the number average molecular weight of the dispersant is from 1000 to 20000, optionally from 2000 to 5000. For example, the number average molecular weight of the dispersant can be 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, or a range consisting of any two of the above values.

When the number average molecular weight of the dispersant is within the above range, the dispersant has excellent suspending ability and can effectively disperse the particles; the dispersant has relatively excellent steric hindrance and can effectively disperse the particles.

The groups of the organic segments in the embodiment of the present application can be detected by infrared spectrophotometry IR. Specifically, the organic segments are measured using a Thermo Nicolet Nexus 670 attenuated total reflection Fourier transform infrared spectrometer (FTIR-ATR). Test, and then refer to the standard GB/T6040-2002 for testing, test range: ATR method 600 ~ 4000cm ^-1 ; repeatability: ± 2cm ^-1 ; resolution: better than 4cm ^-1 ; penetration depth 0.2 ~ 0.6μm.

In the embodiment of the present application, the monomer type of the organic segment (especially suitable for monomers with a relatively small proportion in the organic segment) can be determined by pyrolysis-gas chromatography-mass spectrometry. The specific testing steps are as follows: 0.5 mg of sample is accurately weighed and placed in a sample cup. After being fixed to the injection rod, the sample cup is installed in a pyrolyzer near the gas chromatograph GC inlet. After the pyrolyzer temperature reaches the set temperature, the injection button is pressed, and the sample cup falls rapidly into the pyrolysis furnace core by free fall. In the inert gas _N2 atmosphere, the volatile components are instantly vaporized and carried into the gas chromatography column by the carrier gas for separation. Finally, the volatile components are detected by a flame ionization detector FID or a mass spectrometer MS to obtain a gas chromatogram or a total ion current diagram.

The number average molecular weight of the dispersant in the embodiment of the present application has a well-known meaning in the art and can be measured using commonly used equipment and methods in the art. Gel permeation chromatography (GPC) testing can be used. The specific testing steps are as follows: take an appropriate amount of the sample to be tested (the sample concentration is sufficient to ensure 8%-12% shading), add 20 ml of deionized water, and simultaneously supercharge for 5 minutes (53 KHz/120 W) to ensure that the sample is completely dispersed, and then measure the sample according to GB/T19077-2016/ISO13320:2009 standard.

In the embodiment of the present application, the dispersant can be formed by block polymerization; for example, the preparation method of the dispersant includes:

Step S100 , providing a first monomer and initiating polymerization conditions of the first monomer so that the first monomer is polymerized into an anionic organic segment;

In step S200, a second monomer is provided, and the second monomer and an anionic organic segment are subjected to block polymerization. The anionic organic segment may contain a free radical end. On this basis, the second monomer is further polymerized to form a nonionic organic segment. The main chain of the nonionic organic segment is connected to the main chain of the anionic organic segment.

In the embodiments of the present application, the conditions for block polymerization can be selected according to conditions known in the art, and the initiator, emulsifier, chain transfer agent, etc. required for block polymerization can be selected according to materials known in the art, for example, the initiator includes ammonium sulfate, etc.

Exemplarily, the steps of preparing the dispersant may include:

Add the first monomer, the first initiator and the solvent into a container, heat to 40° C. to 100° C. under a protective gas such as nitrogen, and stir for 4 to 8 hours to obtain a first portion of polymer segments;

Add the second monomer and the second initiator into the container, heat to 40° C. to 100° C. under protective gas such as nitrogen, stir for 4 to 8 hours, and obtain the desired dispersant through dialysis, reduced pressure distillation, etc.

For example, the first initiator and the second initiator may each independently include one or more of potassium persulfate, ammonium persulfate, dibenzoyl peroxide, azobisisobutyronitrile, and the like.

For example, the solvent may include one or more of water, ethanol, dichloromethane, acetone, toluene, N'N' dimethylformamide, and the like.

positive electrode slurry

The embodiment of the present application also provides a positive electrode slurry.

The positive electrode slurry includes positive electrode active particles and a dispersant, wherein the dispersant includes the dispersant of any of the above embodiments.

The embodiment of the present application provides anionic organic segments and nonionic organic segments in the same compound, which can anchor the dispersant on the surface of the positive electrode active particles while playing a role in well dispersing the positive electrode active particles, thereby making the performance of the positive electrode slurry uniform and the leveling property good.

In some embodiments, the mass content of the dispersant is 0.3% to 1.1%, based on the solid content in the positive electrode slurry, for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1% or any two of the above values. Range. Based on the solid content in the positive electrode slurry, the total mass of the solid content in the positive electrode slurry is 100%. The solid content does not include volatile components such as solvents, and mainly includes the total content of components such as positive electrode active particles, dispersant, optional conductive agent, and optional binder.

When the mass content of the dispersant is within the above range, the dispersant can basically cover all the positive electrode active particles, thereby effectively dispersing the positive electrode active particles; the molecular chains of the dispersant basically do not entangle with each other, reducing the risk of flocculation of the positive electrode slurry.

In some embodiments, based on the solid content in the positive electrode slurry, the mass content of the positive electrode active particles is 80% to 99%, for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or a range consisting of any two of the above values.

The positive electrode active particles and the above-mentioned dispersant are used in combination, especially the dispersant with the above-mentioned mass content and the positive electrode active particles with the above-mentioned mass content are used in combination, which can effectively disperse the positive electrode active particles, improve the performance uniformity of the positive electrode slurry, and improve the leveling property of the positive electrode slurry.

In some embodiments, the positive electrode active particles may be made of materials known in the art for use in battery cells. As an example, the positive electrode active particles may include at least one of the following materials: layered active materials (e.g., ternary, lithium/sodium nickelate, lithium/sodium cobaltate, lithium/sodium manganate, lithium/sodium layered, and rock salt layered materials), olivine-type phosphate active materials, and spinel-structured positive electrode active materials (e.g., spinel lithium manganate, spinel lithium nickel manganate, lithium-rich spinel lithium manganate, and lithium nickel manganate). Alternatively, the positive electrode active particles may include olivine-type phosphate active materials.

Illustratively, the general formula of _{the layered positive electrode active} material is: _{LixAyNiaCobMncM (1-abc) Yz} , wherein 0≤x≤2.1, 0≤y≤2.1, and 0.9≤x+y≤2.1; 0≤a≤1, 0≤b≤1 _, 0≤c≤1, and 0.1≤a+b+c≤1; 1.8≤z≤3.5; A _comprises one or more of Na, K, and Mg; M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y comprises one or more of O and F. Optionally, y=0.

Specifically, the layered structure positive active material may include one or more of lithium cobalt oxide LCO, lithium nickel oxide LNO, lithium manganese oxide LMO, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (NCM333), LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (NCM811), and LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523).

Illustratively, the general formula of the olivine-type phosphate active material is: Li _x A _y Me _a M _b P _1-c X _c Y _z , wherein, 0≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more 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 one or more of S, Si, Cl, B, C, and N; and Y includes one or more of O and F. Specifically, the olivine-type phosphate active material includes one or more of LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , and LiCoPO ₄ .

Illustratively, the general formula of the spinel-structured positive _electrode active material is: _{LixAyMnaM2 -aYz ,} wherein, 0≤x≤2, _0≤y≤1 , and 0.9≤x+y≤2; 0.5≤a≤2; 3≤z≤5; A includes one or more of Na, K, and Mg; M includes one or more of Ni, Co, B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y includes one or more of O and F. Specifically, the _{positive electrode} active material of the spinel structure _{includes one or more} of _LiMn2O4 , _{LiNi0.5Mn1.5O4 , LiCr0.3Mn1.7O4 , Li1.1Al0.1Mn1.9O4 , Li2Mn2O4 , and Li1.5Mn2O4 .}

During the charge and discharge process, the battery cell will be accompanied by the deintercalation and consumption of active ions such as Li. The molar content of Li is different in the same state. In the examples of positive electrode active materials in the embodiments of this application, the molar content of Li refers to the initial state of the material, that is, the state before the material is added. When the positive electrode active material is used in a battery system, the molar content of Li may change after charge and discharge cycles.

In the examples of the positive electrode active materials in the embodiments of the present application, the molar content of oxygen O is only a theoretical value. Lattice oxygen release will cause the molar content of oxygen O to change. In practice, the molar content of oxygen O will fluctuate.

Optionally, the positive electrode active particles may include olivine phosphate active materials. Especially when water is used as a solvent, olivine phosphate active materials are prone to agglomeration. When used in combination with the above-mentioned dispersant, the dispersion effect of the olivine phosphate active materials can be effectively improved.

In the embodiments of the present application, the above-mentioned positive electrode active particles may also be modified compounds, and the modified compounds may be used to dope and/or surface-coat the positive electrode active materials. For example, the modified compounds may be doped with transition metal elements, or coated with a carbon layer on the surface of the material.

For example, the olivine-type phosphate active material may include a carbon coating layer or may not include a carbon coating layer. When a carbon coating layer is provided on the surface, the carbon coating layer covers the phosphate particles, which can improve the conductivity of the phosphate particles and improve the performance of the gram capacity.

When the olivine-type phosphate active material is coated with a carbon coating layer, the mass content of the carbon coating layer is 3% to 3.6% based on the total mass of the olivine-type phosphate active material, for example, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, or a range consisting of any two of these values. The carbon coating layer may be fully or partially coated. In both cases, the dispersant can effectively disperse the particles, providing high compatibility.

When the coating is complete, the surface properties of the olivine phosphate active material are determined by the carbon coating layer. The carbon coating layer is mainly a non-polar structure. The carbon coating layer is not easy to adsorb charged particles. It is easy to combine with non-ionic organic segments. The non-ionic organic segments are anchored on the carbon surface of the positive electrode active particles, and the anionic organic segments disperse the particles through electrostatic repulsion.

The carbon coating can also be incomplete, in which case part of the phosphate in the core is exposed. The surface properties of the olivine-type phosphate active material are determined by both the carbon coating and the exposed phosphate. The surface of the carbon coating easily binds to the nonionic organic segments, which are anchored to the carbon surface of the positive electrode active particles. The anionic organic segments disperse the particles through electrostatic repulsion. The exposed phosphate surface easily binds to the anionic organic segments, which disperse the particles through steric hindrance, providing excellent dispersion for the positive electrode active particles.

Of course, the surface of the olivine-type phosphate active material may not include a carbon coating layer. Its surface is determined by phosphate. The phosphate surface is easily combined with anionic organic segments, and the non-ionic organic segments play a role in dispersing particles through steric hindrance, thereby having an excellent dispersing effect on the positive electrode active particles.

In some embodiments, the olivine-type phosphate active material is in the form of particles, and its volume average particle size D _v 50 is 0.5 μm to 10 μm, optionally 0.5 μm to 2 μm, and further optionally 1.20 μm to 1.40 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range consisting of any two of the foregoing values. When the particle size of the olivine-type phosphate active material is within the above range, especially when the particle size is relatively small, problems such as agglomeration are easily caused during the slurry mixing and dispersion process. The use of the above-mentioned dispersant can effectively improve the dispersion of the olivine-type phosphate active material.

In the embodiment of the present application, the volume average particle size D _v 50 of the material is a well-known meaning in the art. The volume average particle size D _v 50 of the material refers to the particle size corresponding to 50% of the volume distribution. It can be detected by using equipment and methods well-known in the art. For measurement, a certain amount of olivine-type phosphate active material is taken as a sample, or the olivine-type phosphate active material in the positive electrode slurry is washed with water and dried as a sample, and the volume average particle size D _v 50 is measured by a Mastersizer 2000E laser particle size analyzer according to the test standard GB/T 19077-2016.

In some embodiments, the positive electrode slurry may further optionally include a positive electrode conductive agent. The present embodiments do not particularly limit the type of positive electrode conductive agent. By way of example, the positive electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the positive electrode conductive agent is ≤5%, based on the total mass of the solid content in the positive electrode slurry being 100%.

In some embodiments, the positive electrode slurry may further optionally include a positive electrode binder. The present application embodiment has no particular restrictions on the type of positive electrode binder. As an example, the positive electrode binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and at least one of fluorine-containing acrylic resins. In some embodiments, based on the total mass of the solid content in the positive electrode slurry being 100%, the mass percentage of the positive electrode binder is ≤5%.

Positive electrode

The embodiment of the present application also provides a positive electrode plate.

The positive electrode sheet includes a positive electrode current collector and a positive electrode film disposed on at least one side of the positive electrode current collector. The positive electrode film includes positive electrode active particles and a dispersant, wherein the dispersant includes any of the dispersants described in any of the above embodiments. The positive electrode sheet can be formed by disposing the positive electrode slurry described in any of the above embodiments on the positive electrode current collector.

The embodiment of the present application arranges anionic organic segments and nonionic organic segments in the same compound, which can anchor the dispersant on the surface of the positive electrode active particles while playing a role in well dispersing the positive electrode active particles, thereby making the performance of the positive electrode slurry uniform and the leveling property better, and making the performance of the positive electrode film layer uniform and the leveling property better.

In some embodiments, based on the mass of the positive electrode film layer, the mass content of the dispersant is 0.3% to 1.1%, for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1% or a range consisting of any two of the above values.

When the mass content of the dispersant is within the above range, the dispersant can basically cover all the positive electrode active particles, thereby effectively dispersing the positive electrode active particles; the molecular chains of the dispersant basically do not entangle with each other, reducing the risk of flocculation of the positive electrode slurry, and making the positive electrode film layer formed by the positive electrode slurry uniform in performance.

In some embodiments, based on the mass of the positive electrode film layer, the mass content of the positive electrode active particles is 80% to 99%, for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or a range consisting of any two of the above values.

The use of positive electrode active particles and the above-mentioned dispersant in combination, especially the use of the above-mentioned mass content of dispersant and the above-mentioned mass content of positive electrode active particles in combination, can effectively disperse the positive electrode active particles, improve the performance uniformity of the positive electrode slurry, and make the positive electrode film layer formed by the positive electrode slurry have uniform performance.

In some embodiments, the positive electrode active particles may be made of materials known in the art for battery cells. As an example, the positive electrode active particles may include at least one of the following materials: layered active materials (such as ternary, lithium nickelate/sodium, lithium cobaltate/sodium, lithium manganate/sodium, lithium/sodium layered and rock salt phase layered materials), olivine phosphate active materials, spinel structured positive electrode active materials (such as spinel lithium manganate, spinel lithium nickel manganate, lithium-rich spinel lithium manganate and lithium nickel manganate, etc.). Optionally, the positive electrode active particles may include olivine phosphate active materials. In particular, when water is used as a solvent, olivine phosphate active materials are prone to agglomeration and the like. When used in combination with the above-mentioned dispersant, the dispersion effect of the olivine phosphate active material can be effectively improved.

In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and comprising a positive electrode active material. For example, the positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material of the metal material layer may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

The positive electrode film layer is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by heating, drying, and roll-pressing. The positive electrode slurry is typically formed by dispersing the positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring them uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

Optionally, the coating method is extrusion coating, transfer coating, blade coating, spray coating, etc.

Optionally, the heating and drying method is air blast heating, infrared heating, microwave heating, nano steam heating, etc., and the heating temperature is 50°C to 180°C.

Optionally, the rolling is cold pressing or hot pressing, and the rolling temperature is 20°C to 180°C.

battery cells

The embodiment of the present application also provides a battery cell.

A battery cell, also known as a rechargeable battery or storage battery, is a battery that can be recharged after discharge to activate the active material and continue to be used. Typically, a battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

In some embodiments, a battery cell includes the positive electrode sheet of any of the above embodiments, and the performance of the positive electrode sheet is stable.

[Negative electrode]

In some embodiments, the battery cell further includes a negative electrode plate.

In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material. For example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposing surfaces of the negative electrode current collector.

The negative electrode active material can be any negative electrode active material known in the art for use in battery cells. For example, the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include at least one of elemental tin, tin oxide, and tin alloys.

In some embodiments, the negative electrode film layer may further optionally include a negative electrode conductive agent. The present embodiments do not particularly limit the type of negative electrode conductive agent. For example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the negative electrode conductive agent based on the total weight of the negative electrode film layer is ≤5%.

In some embodiments, the negative electrode film layer may further include a negative electrode binder. The present application embodiment has no particular restrictions on the type of negative electrode binder. For example, the negative electrode binder may include styrene-butadiene rubber (SBR), water-soluble unsaturated At least one of resin SR-1B, a water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the weight percentage of the negative electrode binder is ≤5% based on the total weight of the negative electrode film layer.

In some embodiments, the negative electrode film layer may optionally include other additives. For example, the other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc. In some embodiments, the weight percentage of the other additives is ≤ 2t% based on the total weight of the negative electrode film layer.

In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer may include at least one of copper, a copper alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

The negative electrode film layer is typically formed by coating the negative electrode slurry onto the negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

The negative electrode sheet does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of the embodiments of the present application further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode sheet of the embodiments of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[Electrolyte]

In some embodiments, the battery cell further includes an electrolyte.

During the charge and discharge process of a battery cell, active ions are embedded and released back and forth between the positive and negative electrodes, and the electrolyte conducts the active ions between the positive and negative electrodes. The present application embodiment does not specifically limit the type of electrolyte, and the electrolyte can be selected based on actual needs.

The electrolyte solution includes an electrolyte salt and a solvent. The types of the electrolyte salt and the solvent are not particularly limited and can be selected according to actual needs.

As an example, the electrolyte salt may include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPO ₂ F ₂ ), lithium difluorobisoxalatophosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).

As an example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film forming agents. Additives may also include positive electrode film-forming additives, and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, additives that improve battery low temperature power performance, etc.

[Isolation film]

In some embodiments, the battery cell further includes a separator. The embodiments of the present application have no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

In some embodiments, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet may be formed into an electrode assembly through a winding process and/or a lamination process.

In some embodiments, the battery cell may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

In some embodiments, the outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell can also be a soft shell, such as a bag-type soft shell. The soft shell can be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

The present invention has no particular restrictions on the shape of the battery cell, which can be cylindrical, square, or any other shape. FIG1 shows a battery cell 5 with a square structure as an example.

In some embodiments, as shown in FIG2 , the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the separator may be formed into an electrode assembly 52 through a winding process and/or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, which can be adjusted according to demand.

The preparation methods of the battery cells of the embodiments of the present application are well known. In some embodiments, a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, separator, and negative electrode sheet can be wound and/or laminated to form an electrode assembly. The electrode assembly is then placed in an outer packaging, dried, and then injected with electrolyte. The battery cell is then vacuum packaged, allowed to stand, formed, and shaped to obtain a battery cell.

In some embodiments of the present application, the battery cells according to the present application can be assembled into a battery module. The battery module can contain multiple battery cells, and the specific number can be adjusted according to the application and capacity of the battery module.

Figure 3 is a schematic diagram of an exemplary battery module 4. As shown in Figure 3 , within the battery module 4, multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, any other arrangement is also possible. Furthermore, the multiple battery cells 5 may be secured together using fasteners.

Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

Figures 4 and 5 are schematic diagrams of a battery pack 1 as an example. As shown in Figures 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The box body 2 is used to cover the lower box body 3 and form a closed space for accommodating the battery modules 4. Multiple battery modules 4 can be arranged in the battery box in any manner.

Electrical devices

The embodiments of the present application also provide an electrical device, which includes at least one of the battery cells, battery modules, or battery packs of the embodiments of the present application. The battery cells, battery modules, or battery packs can be used as power sources for the electrical device, or as energy storage units for the electrical device. The electrical device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

The electrical device can select battery cells, battery modules or battery packs according to its usage requirements.

FIG6 is a schematic diagram of an exemplary electric device 6. The electric device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the electric device 6, a battery pack or battery module may be used.

As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such an electric device is usually required to be lightweight and thin, and may use a battery cell as a power source.

Example

The following examples describe the disclosure of the present invention in more detail. These examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present invention will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

Example 1 Preparation of positive electrode slurry

Preparation of dispersant

0.1 parts by weight of initiator potassium persulfate, 50 parts by weight of acrylic acid, and 500 parts by weight of water were added to a reaction vessel, and stirred at 80° C. for 4 hours under nitrogen protection;

0.1 parts by weight of initiator potassium persulfate and 50 parts by weight of ethylene glycol were added to a reaction vessel, stirred at 80° C. for 4 hours under nitrogen protection, and unpolymerized small molecular monomers were removed by reduced pressure distillation to obtain a dispersant.

Preparation of cathode slurry

The positive electrode active material, dispersant, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an appropriate amount of solvent deionized water to form a uniform positive electrode slurry, wherein the positive electrode active material, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are added in a weight ratio of 95:2:1.

The positive electrode active material includes lithium iron phosphate LiFePO ₄ and a carbon coating layer disposed on the surface of the lithium iron phosphate. Based on the total mass of the positive electrode active material, the mass content of the carbon coating layer is 3.2%.

Comparative Example 1

A positive electrode slurry was prepared by a method similar to that of Example 1. The difference from Example 1 was that the dispersant in the positive electrode slurry was polyacrylic acid.

Comparative Example 2

A positive electrode slurry was prepared by a method similar to that of Example 1. The difference from Example 1 was that the dispersant in the positive electrode slurry was polyethylene glycol.

Example 2-1 to Example 2-5

A positive electrode slurry was prepared by a method similar to that of Example 1. The difference from Example 1 was that at least one of the polymerization degree of the anionic organic segment and the polymerization degree of the nonionic organic segment in the dispersant in the positive electrode slurry was adjusted.

Example 3-1 to Example 3-9

A positive electrode slurry was prepared using a method similar to that of Example 1. The difference from Example 1 was that the type of dispersant in the positive electrode slurry was adjusted.

in,

In Examples 3-1 to 3-5, the type of anionic organic segments in the dispersant was adjusted;

In Examples 3-6 to 3-9, the types of nonionic organic segments in the dispersant were adjusted.

Example 4-1 and Example 4-2

A positive electrode slurry was prepared using a method similar to that of Example 1. The difference from Example 1 was that the molecular weight of the dispersant in the positive electrode slurry was adjusted.

Example 5-1 to Example 5-3

A positive electrode slurry was prepared by a method similar to that of Example 1. The difference from Example 1 was that the carbon coating amount of the positive electrode active particles in the positive electrode slurry was adjusted.

Example 6

A positive electrode slurry was prepared by a method similar to that of Example 1. The difference from Example 1 was that the volume average particle size D _v 50 of the positive electrode active particles in the positive electrode slurry was adjusted.

Preparation of battery cells

1. Preparation of positive electrode sheet

Aluminum foil was used as the positive electrode current collector.

The positive electrode slurry prepared in each embodiment and comparative example was evenly coated on the surface of the positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet was obtained.

2. Preparation of negative electrode sheet

Copper foil was used as the negative electrode current collector.

The negative electrode active material artificial graphite, the binder styrene-butadiene rubber (SBR), the thickener sodium carboxymethyl cellulose (CMC-Na), and the conductive agent carbon black (Super P) are fully stirred and mixed in an appropriate amount of solvent deionized water in a weight ratio of 96.2:1.8:1.2:0.8 to form a uniform negative electrode slurry; the negative electrode slurry is evenly coated on the surface of the negative electrode current collector copper foil, and after drying and cold pressing, the negative electrode sheet is obtained.

3. Isolation film

A porous polyethylene (PE) film is used as the separator.

4. Preparation of electrolyte

In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain an electrolyte solvent, and then lithium salt lithium hexafluorophosphate and the mixed solvent are mixed to prepare an electrolyte with a lithium salt concentration of 1 mol/L.

5. Preparation of battery cells

The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive electrode sheet and the negative electrode sheet to serve as an isolation, and then wound to obtain an electrode assembly; the electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte, and after vacuum packaging, standing, forming, shaping and other processes, a lithium-ion battery is obtained.

Performance Testing

1. Slurry state test of positive electrode slurry

Take the positive electrode slurry, observe the slurry flow state, and classify it according to the following standards:

If the cathode slurry has no agglomerates and flows in a continuous stream, it is rated as excellent;

If the cathode slurry has no obvious agglomeration and has fluidity, but cannot be in the form of a continuous water flow, it is recorded as good;

If the positive electrode slurry has almost no fluidity and is paste-like, it is marked as poor.

2. Test of sieving time of positive electrode slurry

Take 500 ml of positive electrode slurry and pour it into a beaker (beaker with scale) through a 150-mesh filter. Record the time it takes for the beaker to contain 400 ml of positive electrode slurry, which is recorded as the sieving time. A faster sieving time indicates that the slurry is less likely to agglomerate.

3. Viscosity test of positive electrode slurry

Add the positive electrode slurry to the measuring cup, install the No. 63 rotor in the rotational viscometer, adjust the rotor until the positive electrode slurry is below the scale line, adjust the speed of the rotational viscometer to 13 rpm, and read the viscosity after the display stabilizes.

4. Standing gel time of positive electrode slurry

The positive electrode slurry was placed at room temperature and the time for gelation of the positive electrode slurry was recorded. The longer the gelation time was, the more stable the slurry was.

Test results

The test results are shown in Tables 1 and 2.

Table 1

In Table 1, n represents the degree of polymerization of the anionic organic segment; m represents the degree of polymerization of the nonionic organic segment.

As can be seen from Table 1, in Comparative Examples 1 and 2, polyacrylic acid or polyethylene glycol alone is added as a dispersant to the positive electrode slurry, and the dispersion of the particles in the positive electrode slurry is relatively poor; when a mixture of polyacrylic acid and polyethylene glycol is added as a dispersant to the positive electrode slurry, polyacrylic acid and polyethylene glycol each play a dispersing role, which can improve the dispersion of the particles in the positive electrode slurry to a certain extent, but the performance of the slurry is unstable and prone to coagulation and other problems.

Compared with the comparative example, the embodiment of the present application combines the anionic organic segment and the non-ionic organic segment in the same molecular chain. When one segment plays the role of anchoring on the surface of the positive electrode active particles, the other plays a dispersing role, so that the dispersant can play a role of well dispersing the positive electrode active particles, thereby making the performance of the positive electrode slurry stable, uniform, and with good leveling properties.

In Examples 2-1 to 2-5, the ratio of the degree of polymerization of the anionic organic segment and the non-ionic organic segment is adjusted, which can further improve the dispersion performance, especially when the ratio of the degree of polymerization is 0.4 to 2.3, and can be optionally 0.7 to 1.5, the dispersion performance is further improved, so that the particles in the positive electrode slurry are evenly dispersed, the performance is stable and uniform, and the leveling property is good.

In Examples 3-1 to 3-9, by adjusting the type of anionic organic segments or nonionic organic segments, the dispersing properties of the dispersant can be further adjusted, so that the particles in the positive electrode slurry are evenly dispersed, the performance is stable and uniform, and the leveling property is good.

In Example 4-1 to Example 4-2, the dispersion performance can be further improved by regulating the number average molecular weight of the dispersant, especially when the number average molecular weight is 2000 to 10000, and can be optionally 2000 to 5000, the dispersion performance is further improved, so that the particles in the positive electrode slurry are evenly dispersed, the performance is stable and uniform, and the leveling property is good.

Table 2

As can be seen from Table 2, the carbon coating amount of the positive electrode active particles in Examples 5-1 to 5-3 was adjusted. Based on the total mass of the positive electrode active particles, the mass content of the carbon coating layer was 3% to 3.6%. The dispersant had an excellent dispersion effect on the particles, indicating that the dispersant is suitable for systems with different carbon coating amounts and has a wide range of applications.

In Example 6, the volume average particle size D _v 50 of the positive electrode active particles was adjusted. When the volume average particle size was 0.5 μm to 10 μm, optionally 0.5 μm to 2 μm, and further optionally 1.20 μm to 1.40 μm, the dispersant had excellent dispersibility on the positive electrode active particles.

Although illustrative embodiments have been shown and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on the present application, and that changes, substitutions, and modifications may be made to the embodiments without departing from the spirit, principles, and scope of the present application.

Claims (25)

A dispersant includes an anionic organic segment and a nonionic organic segment, wherein the anionic organic segment includes a carbon-carbon main chain and a first group connected to the carbon-carbon main chain, and the nonionic organic segment is connected to the carbon-carbon main chain and includes a second group, wherein the polarity of the second group is smaller than that of the first group. The dispersant according to claim 1, wherein the anionic organic segment comprises a segment represented by formula I,
R ₁ , R ₂ and R ₃ each independently include a hydrogen atom, a C1 to C3 alkyl group; R ₄ includes a single bond or a C1 to C3 alkylene group; R ₅ is a first group, R ₅ includes carboxylic acid or its anion, sulfonic acid or its anion, phosphoric acid or its anion, pyrrolidone or its anion, amide or its anion, or carboxylate group; n represents the degree of polymerization, and n is greater than or equal to 2. The dispersant according to claim 2, wherein R ₁ , R ₂ and R ₃ each independently include a hydrogen atom or a methyl group; and/or R ₄ includes a single bond or a methylene group. The dispersant according to claim 2 or 3, wherein the segment represented by formula I comprises one or more of the segments represented by formula I-1 to the segments represented by formula I-14,

The dispersant according to any one of claims 1 to 4, wherein the second group comprises one or more of an ether bond, a phenyl group and a hydroxyl group. The dispersant according to claim 5, wherein The nonionic organic segment containing the ether bond includes one or more of a polyethylene glycol segment, a polyglycerol segment and a polyoxypropylene segment; and/or The nonionic organic segment containing the phenyl group includes one or more of a polystyrene segment and a polyaniline segment; and/or The nonionic organic segment containing the hydroxyl group includes a polyenol segment. The dispersant according to claim 6, wherein the polyenol segment comprises one or more of a polyvinyl alcohol segment and a polypropylene alcohol segment. The dispersant according to claim 7, wherein the nonionic organic segment comprises one or more of a polyethylene glycol segment and a polystyrene segment. The dispersant according to any one of claims 1 to 8, wherein the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the nonionic organic segment is 0.4 to 2.3. The dispersant according to claim 9, wherein the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the nonionic organic segment is 0.7 to 1.5. The dispersant according to any one of claims 1 to 10, wherein the number average molecular weight of the dispersant is 1,000 to 20,000. The dispersant according to claim 11, wherein the number average molecular weight of the dispersant is 2000 to 5000. A positive electrode slurry comprises positive electrode active particles and the dispersant according to any one of claims 1 to 12. The positive electrode slurry according to claim 13, wherein the mass content of the dispersant is 0.3% to 1.1% based on the solid content in the positive electrode slurry. The positive electrode slurry according to claim 13 or 14, wherein the positive electrode active particles include an olivine-type phosphate active material. The positive electrode slurry according to claim 15, wherein the olivine-type phosphate active material comprises phosphate particles and a carbon coating layer coated on the surface of the phosphate particles. The positive electrode slurry according to claim 16, wherein the mass content of the carbon coating layer is 3% to 3.6% based on the total mass of the olivine-type phosphate active material. The positive electrode slurry according to any one of claims 15 to 17, wherein the olivine-type phosphate active material comprises a compound of the general formula Li _x A _y Me _a M _b P _1-c X _c Y _z , wherein 0≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A comprises one or more of Na, K, and Mg; Me comprises one or more of Mn, Fe, Co, and Ni; M comprises B, Mg, Al, Si, P, S, Ca, Sc, One or more of Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; and Y includes one or more of O and F. The positive electrode slurry according to any one of claims 13 to 18, wherein the volume average particle size D _v 50 of the positive electrode active particles is 0.5 μm to 10 μm. The positive electrode slurry according to claim 19, wherein the volume average particle size D _v 50 of the positive electrode active particles is 0.5 μm to 2 μm. A positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector, wherein the positive electrode film layer comprises positive electrode active particles and a dispersant according to any one of claims 1 to 12. The positive electrode sheet according to claim 21, wherein the mass content of the dispersant is 0.3% to 1.1% based on the mass of the positive electrode film layer. The positive electrode sheet according to claim 21 or 22, wherein the positive electrode active particles include olivine-type phosphate active materials. A battery comprising the positive electrode sheet according to any one of claims 21 to 23. An electrical device comprising the battery as claimed in claim 24.