CN222051815U

CN222051815U - Electrode plate and secondary battery

Info

Publication number: CN222051815U
Application number: CN202323407796.6U
Authority: CN
Inventors: 郭月
Original assignee: Weilai Battery Technology Anhui Co ltd
Current assignee: Weilai Battery Technology Anhui Co ltd
Priority date: 2023-12-13
Filing date: 2023-12-13
Publication date: 2024-11-22
Anticipated expiration: 2033-12-13

Abstract

The utility model discloses an electrode plate and a secondary battery, wherein the electrode plate comprises: a current collector, wherein the length of the current collector is a mm, and the width of the current collector is b mm; an active material layer, wherein the active material layer is arranged on the surface of the current collector, and wherein the active material layer comprises a first region and a second region arranged around the first region, wherein the length of the first region in the width direction of the electrode plate is t mm, and the length of the first region in the length direction of the electrode plate is nmm, and in the width direction of the electrode plate, one end of the first region extends to the edge of the current collector; the coating weight of the first region is xg/m ² , the coating weight of the second region is yg/m ² , the compaction density of the first region is pg/cm ³ , and the compaction density of the second region is qg/cm ³ ; and the electrode plate satisfies: x＜y, p＜q, 5≤n≤50, 0.6b≤t≤b.

Description

Electrode plate and secondary battery

Technical Field

The utility model relates to the technical field of lithium batteries, in particular to an electrode plate and a secondary battery.

Background

With the continuous high-speed development of the fields of large-scale energy storage, electric automobiles, consumer electronics and the like, the demand for lithium ion batteries is continuously increased, and the performances of energy density, quick charge capacity, safety reliability and the like are gradually approaching the limit, so that new breakthrough is required to be technically sought, innovation is carried out on a chemical system, a battery cell structure and a manufacturing process, and further the continuous improvement of the comprehensive capacity of the new generation of lithium ion batteries is realized.

Especially in cylindric lithium ion battery, along with the pursuit to the energy density constantly increases, electric core pole piece thickness is thicker and thicker, compaction density is higher and higher, electric core crowd margin is also higher and higher, leads to electric core formation process to only adopt very little electric current to go on, if the electric current is too big then can be because local gas production is too fast, can't effectively discharge, leads to locally to produce the bubble, influences the interface contact of pole piece and diaphragm, causes the destruction even to the pole piece inside, directly influences electric core normal use. In addition, the excessively small formation rate brings low production efficiency, high manufacturing cost and relatively low inorganic content of a generated solid electrolyte interface film (SEI film) due to small current formation, so that the stability is poor and potential safety hazards of the battery cells are aggravated. Meanwhile, the cell design form with high pole piece thickness, high compaction density and high group margin greatly influences the transportation of electrolyte in the cell, and deteriorates the electrolyte recharging path in the cell use process, so that the cell dynamics is reduced, and the cell cycle life is influenced.

Disclosure of utility model

The embodiment of the utility model provides an electrode plate and a secondary battery, which are used for solving the problems of low production efficiency, high manufacturing cost, relatively low inorganic content of an SEI film, poor stability and the like caused by small current in the existing electrode plate formation.

In one aspect, an embodiment of the present utility model provides an electrode slice, including:

The length of the current collector is a mm, and the width of the current collector is b mm;

An active material layer disposed on the surface of the current collector, the active material layer including a first region having a length t mm in the width direction of the electrode sheet and a second region disposed around the first region having a length n mm in the length direction of the electrode sheet, one end of the first region extending to an edge of the current collector in the width direction of the electrode sheet;

The coating weight of the first area is x g/m ², the coating weight of the second area is y g/m ², the compaction density of the first area is p g/cm ³, and the compaction density of the second area is q g/cm ³;

The pole piece satisfies: x is less than y, p is less than q, n is more than or equal to 5 and less than or equal to 50, n is more than or equal to 5 and less than or equal to 5 and t is more than or equal to 50.6b and less than or equal to b.

In some embodiments, the orthographic projection of the first region on the current collector has a shape of triangle, rectangle, diamond, polygon with a side number greater than 4, circle, ellipse, or irregular shape with one side being arc.

In some embodiments, the first region is disposed at an upper portion of the electrode tab along a height direction of the battery cell formed by the electrode tab.

In some embodiments, 3000.ltoreq.a.ltoreq.6000.

In some embodiments, 40.ltoreq.b.ltoreq.120.

In some embodiments, 80.ltoreq.x.ltoreq.110.

In some embodiments, 95.ltoreq.y.ltoreq.120.

In some embodiments, 1.2.ltoreq.p.ltoreq.1.7.

In some embodiments, 1.4.ltoreq.q.ltoreq.1.8.

In some embodiments, the first regions are provided with at least two, a spacing between adjacent first regions is e mm, an area of the active material layer is S ₁, a total area of the first regions is S ₂, and the electrode sheet satisfies one of the following conditions:

(1)50≤e≤1000；

(2)0.02S₁≤S₂≤0.15S₁。

in some embodiments, the first region further satisfies at least one of the following conditions:

(3)5≤n≤30；

(4)100≤e≤300。

in some embodiments, the electrode sheet satisfies at least one of the following conditions:

(5)x+2≤y≤1.5x；

(6)p+0.05≤q≤1.5p。

In some embodiments, the electrode sheet is a positive electrode sheet that satisfies at least one of the following conditions:

(7)x+8≤y≤1.3x；

(8)p+0.12≤q≤1.3p；

(9) The current collector is aluminum;

(10) The active material layer consists of a positive electrode active material, a binder and a conductive agent; wherein the positive electrode active material is LiNi_0.5Co_0.2Mn_0.3O₂、LiNi_0.6Co_0.2Mn_0.2O₂、LiNi_0.8Co_0.1Mn_0.1O₂、LiNi_0.9Co_0.05Mn_0.05O₂、LiNi_0.92Co_0.05Mn_0.03O₂ or LiNi _0.95Co_0.05O₂; the binder is polyvinylidene fluoride; the conductive agent is conductive carbon black.

In some embodiments, the electrode sheet is a negative electrode sheet that satisfies at least one of the following conditions:

(11)x+4≤y≤1.3x；

(12)p+0.06≤q≤1.3p；

(13) The current collector is copper;

(14) The active material layer consists of artificial graphite, a silicon oxide compound, a binder, a thickener and a conductive agent; wherein the silicon oxide is SiO _x, x is more than or equal to 0.5 and less than or equal to 1.5; the binder is polyacrylic acid and styrene-butadiene rubber; the thickener is sodium carboxymethyl cellulose; the conductive agent is conductive carbon black.

In some embodiments, a graded region is provided on a side of the first region near the second region, and/or a graded region is provided on a side of the second region away from the first region;

Wherein, the width of gradual change district is k mm, the gradual change district satisfies: k is less than or equal to n/5,1 k is more than or equal to 10.

Another aspect of the embodiments of the present utility model provides a secondary battery, including a battery cell, the battery cell including a positive electrode tab and a negative electrode tab, at least one of the positive electrode tab and the negative electrode tab adopting the tab according to any one of the above-described embodiments;

The battery cell is of a winding structure, the width direction of the electrode pole piece is the same as the axial direction of the battery cell, and the length direction of the electrode pole piece is the same as the winding direction of the battery cell.

In some embodiments, one end of the cell in the axial direction has a fluid injection port, and one end of the first region extending to the edge of the current collector faces the fluid injection port.

Compared with the prior art, the utility model has the following advantages:

According to the electrode pole piece provided by the utility model, the active material layer is partitioned, the coating weight and the compaction density of the first area in the active material layer are set smaller than those of the second area, so that a part of pole piece area (first area) with relatively high porosity is provided under the conditions of high pole piece thickness, high compaction density and high group margin, after the electrode pole piece is wound to form a cylindrical battery, the first area is used as a path for gas discharge in the formation process and rapid electrolyte recovery in the use of the battery core, thereby greatly improving the formation rate of the battery core, improving the inorganic content in the SEI film, improving the stability of the SEI film, reducing the formation time, reducing the manufacturing cost, synchronously improving the circulation capacity retention rate of the battery core and improving the dynamics of the battery core.

Drawings

FIG. 1 is a schematic view of an electrode plate according to an embodiment of the present utility model;

FIG. 2 is a schematic view of an electrode plate according to an embodiment of the present utility model;

Fig. 3 is a view illustrating a state in which an electrode tab according to an embodiment of the present utility model is used in a secondary battery.

The drawings are marked with the following description:

1. a first region; 2. a second region.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present utility model. The present utility model may be embodied in many other forms than those herein described, and those skilled in the art will readily appreciate that the present utility model may be similarly embodied without departing from the spirit or essential characteristics thereof, and therefore the present utility model is not limited to the specific embodiments disclosed below.

In the description of the present utility model, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present utility model and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present utility model.

In the description of the present utility model, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present utility model can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.

In the description of the present utility model, the descriptions of the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present utility model.

Referring to fig. 1 and 2, an embodiment of the present utility model discloses an electrode pad, which includes: the current collector comprises a current collector and an active material layer, wherein the length of the current collector is a mm, and the width of the current collector is b mm; the active material layer is arranged on the surface of the current collector, the active material layer comprises a first area 1 and a second area 2 arranged around the first area, the length of the first area 1 in the width direction of the electrode pole piece is t mm, the length of the first area in the length direction of the electrode pole piece is n mm, and one end of the first area 1 extends to the edge of the current collector in the width direction of the electrode pole piece; the coating weight of the first area 1 is x g/m ², the coating weight of the second area 2 is y g/m ², the compaction density of the first area 1 is p g/cm ³, and the compaction density of the second area 2 is q g/cm ³; the electrode plate meets the following conditions: x is less than y, p is less than q, n is more than or equal to 5 and less than or equal to 50,0.6b t is more than or equal to b.

In some embodiments, the orthographic projection of the first region 1 on the current collector is triangular, rectangular, rhombic, polygonal with a number of sides greater than 4, circular, elliptical, or an irregular shape with one side being arc-shaped. In some embodiments, the orthographic projection of the first region 1 on the current collector is rectangular in shape.

In some embodiments, the first region 1 is disposed at an upper portion of the electrode tab along a height direction of the battery cell formed by the electrode tab. By this design, the first region can be used as a venting channel, in particular to facilitate the escape of gas from the first region during the formation stage.

In some alternative embodiments, 3000.ltoreq.a.ltoreq.6000, and in particular, a may be 3000, 3500, 4000, 4500, 5000, 5500, 6000 or any value therebetween.

In some alternative embodiments, 40.ltoreq.b.ltoreq.120, and in particular, b may be 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, or any value therebetween.

In some alternative embodiments, 80.ltoreq.x.ltoreq.110, and in particular, x may be 80, 85, 90, 95, 100, 105, 110 or any value therebetween.

In some alternative embodiments, 95.ltoreq.y.ltoreq.120, and in particular, y may be 95, 100, 105, 110, 115, 120 or any value therebetween.

In some alternative embodiments, 1.2.ltoreq.p.ltoreq.1.7, with p being, in particular, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, or any value therebetween.

In some alternative embodiments, 1.4.ltoreq.q.ltoreq.1.8, and in particular q is 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, or any value therebetween.

In some embodiments, the first regions 1 are provided with at least two, the spacing between the boundaries of adjacent first regions 1 is e mm, the area of the active material layer is S ₁, the total area of the first regions is S ₂, and the electrode sheet satisfies one of the following conditions:

(1)50≤e≤500；

(2)0.02S1≤S2≤0.15S1。

In some embodiments, the first region 1 further satisfies at least one of the following conditions:

(3)5≤n≤30；

(4)100≤e≤300。

(5)x+2≤y≤1.5x；

(6)p+0.05≤q≤1.5p。

(7)x+8≤y≤1.3x；

(8)p+0.12≤q≤1.3p；

(9) The current collector is aluminum;

In some embodiments, the electrode tab is a negative electrode tab that satisfies at least one of the following conditions:

(11)x+4≤y≤1.3x；

(12)p+0.06≤q≤1.3p；

(13) The current collector is copper;

By selecting the parameters and the chemical composition of the active materials, the gas discharge efficiency in the formation process and the rapid electrolyte recharging efficiency in the use of the battery cell are further improved, so that the formation rate of the battery cell can be greatly improved.

In some embodiments, a gradual change region is arranged on one side, close to the second region, of the first region; a gradual change region is arranged on one side, far away from the first region, of the second region; wherein, the width of gradual change district is k mm, the gradual change district satisfies: k is less than or equal to n/5,1 k is more than or equal to 10. By arranging the gradual change region, the safety and mechanical performance of the electrode plate are further improved.

According to fig. 3, the utility model also discloses a secondary battery comprising a battery cell, wherein the battery cell comprises a positive electrode plate and a negative electrode plate, and the positive electrode plate and the negative electrode plate adopt the electrode plate according to any one of the above embodiments. Of course, the parameters of the positive electrode plate are determined according to the specification of the positive electrode plate, and the parameters of the negative electrode plate are determined according to the specification of the negative electrode plate, which is not described herein.

As can be seen from fig. 3, the battery cell is in a winding structure, the width direction of the electrode plate is the same as the axial direction of the battery cell, and the length direction of the electrode plate is the same as the winding direction of the battery cell.

In some embodiments, one end of the cell in the axial direction has a fluid injection port, and one end of the first region extending to the edge of the current collector faces the fluid injection port. So that the gas during formation overflows from the channel formed by the first region.

It is also noted that in some embodiments, the secondary battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. The electrode plate can be used as the positive electrode plate of the secondary battery when the electrode plate is the positive electrode plate, and can be used as the negative electrode plate of the secondary battery when the electrode plate is the negative electrode plate. The electrolyte and separator may be any known in the art, and may be selected as desired by those skilled in the art.

In some embodiments, secondary batteries include, but are not limited to: lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries.

The application is not particularly limited to the type of battery, and can be any type of lithium ion battery, such as button type, cylinder type, soft package type lithium ion battery and the like.

The utility model also provides a device comprising the secondary battery. Thus, the device has all the features and advantages of the secondary battery provided by the utility model, and is not described herein.

In some embodiments, the apparatus of the present utility model includes, but is not limited to: notebook computers, pen-input computers, mobile computers, electronic book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, video recorders, liquid crystal televisions, hand-held cleaners, portable CD-players, mini-compact discs, transceivers, electronic notebooks, calculators, memory cards, portable audio recorders, radios, standby power supplies, motors, automobiles (e.g., electric vehicles, hybrid electric vehicles, or plug-in hybrid electric vehicles), motorcycles, mopeds, bicycles, lighting fixtures, toys, game machines, watches, electric tools, flashlights, cameras, home-use large-sized batteries, or lithium-ion capacitors, and the like.

The utility model is described in further detail below in connection with specific examples which are not to be construed as limiting the scope of the utility model as claimed. In the following test, the electrode sheet had a length a of 4500mm and b=80 mm in size.

Comparative example 1:

(1) Mixing high-energy-density artificial graphite as a cathode active material, siOx material, sodium carboxymethyl cellulose (CMC-Na) as a thickener, styrene-butadiene rubber (SBR) as a binder and conductive carbon black as a conductive agent according to the weight ratio of 82.8 percent to 14.6 percent to 0.6 percent to 0.8 percent, adding deionized water, obtaining cathode slurry (the solid content is 40-49 percent and the viscosity is 2000-6000 mPa.s) under the action of a vacuum stirrer, and coating the slurry on copper foil (4500 mm multiplied by 80 mm) with the thickness of 5 mu m by using an extrusion coater according to a normal coating mode to complete a coating procedure. Drying, cold pressing and slitting to finish the preparation of the negative electrode plate; the coating weight of the negative electrode plate after cold pressing is 106g/m ², and the compaction density is 1.6g/cm ³ (as information in table 1);

(2) Mixing a secondary composite particle NCM811 material (LiNi _0.8Co_0.1Mn_0.1O₂), a binder polyvinylidene fluoride PVDF and conductive carbon black with the mass ratio of 97.5% to 1.4% to 1.1%, adding NMP (N-methylpyrrolidone), obtaining positive electrode slurry (the solid content is 70-80% and the viscosity is 3500-6500 mPa.s) under the action of a vacuum stirrer, and coating the slurry on aluminum foil (4500 mm multiplied by 80 mm) with the thickness of 10 mu m by using a squeeze coater according to a normal coating mode to finish a coating process. Drying, cold pressing and slitting to finish the preparation of the positive pole piece;

(3) The positive electrode plate and the negative electrode plate are respectively die-cut and then are wound together with a diaphragm (a base film 7 mu mPE diaphragm, two sides of which are respectively coated with Al2O3 ceramic coatings with the thickness of 2 mu m) to form a bare cell, the bare cell is placed into a cylindrical shell, welded and packaged, and the cylindrical cell is prepared through the procedures of liquid injection, formation, capacity division, standing and the like.

Comparative examples 2 to 3

The procedure is as above, and the implementation parameters are adjusted and implemented according to table 1.

Examples 1 to 12:

The procedure for the implementation of examples 1 to 12 was the same as that of comparative example 1, except that: the first and second zone settings of examples 1-10 were performed according to fig. 1 and the first and second zone settings of examples 11-12 were performed according to fig. 2. In the case of coating, the positive electrode active material layer was normally coated (not partition-coated) in the positive electrode sheet, and the negative electrode active material layer was partition-coated in the negative electrode sheet, and the arrangement of the partition-coated coating regions, the Coating Weights (CW) corresponding to the respective partition-coated regions, the compacted densities, and the like are shown in table 1.

Wherein, the steps for carrying out the partition coating are as follows: coating the slurry on the copper foil using a gravure coater, the coating location including only the second region (e.g., high CW), and drying; then coating the slurry on the copper foil subjected to gravure coating by using an extrusion coater according to a normal coating mode, namely coating on a first area to complete a coating process; and then drying, cold pressing and slitting to finish the preparation of the negative electrode plate.

TABLE 1

The testing method comprises the following steps:

Cyclic capacity retention test:

And (3) under the condition of 25 ℃, the prepared battery cell is charged to 4.2V at a constant current with a 1C multiplying power, and then is charged to a constant voltage until the current is less than 0.05C. After standing for 5 minutes, the initial discharge capacity was again recorded by discharging to 2.5V at 1C magnification. The battery cell was subjected to charge and discharge cycles of 500 times by the above method, and the discharge capacity of each time was recorded. Capacity retention rate of the lithium ion secondary battery at 25 ℃ for 500 cycles = 500 th discharge capacity/initial discharge capacity x 100%.

Through test detection, the conditions of the total formation duration, the battery cell charging rate limit and the battery cell circulation capacity retention rate of each embodiment are as follows in table 2:

TABLE 2

As can be seen from the analysis results in Table 2, the total formation time, the limit of the battery cell charging rate and the battery cell circulation capacity retention rate are greatly improved by adopting the technical scheme of the utility model.

It should be noted that while the above describes exemplifying embodiments of the utility model, there are several different embodiments of the utility model, which are intended to be illustrative, and that the scope of the utility model is defined by the appended claims.

Claims

1. An electrode plate, characterized by comprising:

A current collector, wherein the length of the current collector is a mm, and the width of the current collector is b mm;

An active material layer, wherein the active material layer is disposed on the surface of the current collector, the active material layer comprises a first region and a second region disposed around the first region, the length of the first region in the width direction of the electrode sheet is t mm, the length of the first region in the length direction of the electrode sheet is n mm, and in the width direction of the electrode sheet, one end of the first region extends to the edge of the current collector;

The coating weight of the first region is xg/m ² , the coating weight of the second region is yg/m ² , the compaction density of the first region is pg/cm ³ , and the compaction density of the second region is qg/cm ³ ;

The electrode plate satisfies: x＜y, p＜q, 5≤n≤50, 0.6b≤t≤b.

2. The electrode plate according to claim 1, characterized in that the shape of the orthographic projection of the first region on the current collector is a triangle, a rectangle, a rhombus, a polygon with more than 4 sides, a circle, an ellipse, or an irregular shape with one side being an arc; and/or

Along the height direction of the battery cell formed by the electrode sheet, the first region is arranged on the upper part of the electrode sheet; and/or

3000≤a≤6000; and/or

40≤b≤120; and/or

80≤x≤110; and/or

95≤y≤120; and/or

1.2≤p≤1.7; and/or

1.4≤q≤1.8.

3. The electrode sheet according to claim 1 or 2, characterized in that at least two first regions are provided, the spacing between adjacent first regions is e mm, the area of the active material layer is S ₁ , the total area of the first regions is S ₂ , and the electrode sheet satisfies one of the following conditions:

(1)50≤e≤1000;

(2)0.02S ₁ ≤S ₂ ≤0.15S ₁ .

4. The electrode plate according to claim 3, characterized in that the first region further satisfies at least one of the following conditions:

(3)5≤n≤30;

(4)100≤e≤300.

5. The electrode plate according to claim 1, characterized in that the electrode plate satisfies at least one of the following conditions:

(5)x+2≤y≤1.5x;

(6)p+0.05≤q≤1.5p.

6. The electrode plate according to any one of claims 1, 2, 4, and 5, characterized in that the electrode plate is a positive electrode plate, and the positive electrode plate satisfies at least one of the following conditions:

(7)x+8≤y≤1.3x;

(8)p+0.12≤q≤1.3p;

(9) The current collector is aluminum;

(10) The active material layer is composed of a positive electrode active material, a binder and a conductive agent; wherein the positive electrode active material is LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.9 Co _0.05 Mn _0.05 O ₂ , LiNi _0.92 Co _0.05 Mn _0.03 O ₂ or LiNi _0.95 Co _0.05 O ₂ ; the binder is polyvinylidene fluoride; and the conductive agent is conductive carbon black.

7. The electrode plate according to any one of claims 1, 2, 4, and 5, characterized in that the electrode plate is a negative electrode plate, and the negative electrode plate satisfies at least one of the following conditions:

(11)x+4≤y≤1.3x;

(12)p+0.06≤q≤1.3p;

(13) The current collector is copper;

(14) The active material layer is composed of artificial graphite, silicon oxide, a binder, a thickener and a conductive agent; wherein the silicon oxide is SiO _x , 0.5≤x≤1.5; the binder is polyacrylic acid and styrene-butadiene rubber; the thickener is sodium carboxymethyl cellulose; and the conductive agent is conductive carbon black.

8. The electrode sheet according to claim 1, characterized in that a gradient zone is provided on a side of the first region close to the second region, and/or a gradient zone is provided on a side of the second region away from the first region;

The width of the gradient zone is k mm, and the gradient zone satisfies: k≤n/5, 1≤k≤10.

9. A secondary battery, characterized in that it comprises a battery cell, wherein the battery cell comprises a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet is an electrode sheet according to any one of claims 1 to 6, and/or the negative electrode sheet is an electrode sheet according to any one of claims 1 to 5 and 7;

The battery cell is a winding structure, the width direction of the electrode sheet is the same as the axial direction of the battery cell, and the length direction of the electrode sheet is the same as the winding direction of the battery cell.

10 . The secondary battery according to claim 9 , wherein one end of the battery cell in the axial direction has a liquid injection port, and one end of the first region extending to the edge of the current collector faces the liquid injection port.