CN219066845U - Negative plate and battery - Google Patents

Abstract

The utility model provides a negative electrode sheet and a battery, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer coated on the negative electrode current collector, and the negative electrode active material layer sequentially comprises a first area, a second area and a third area along the width direction of the negative electrode sheet, wherein the specific surface area of the second area is larger than the specific surface area of any one of the first area and the third area. The capillary adsorption effect of the electrolyte in the second area is enhanced, namely the liquid absorption capacity of the second area is larger than that of the first area and the third area, more lithium ions can be embedded in the larger specific surface area, and the lithium embedding capacity of the second area is improved. Therefore, the lithium precipitation condition in the middle area of the negative electrode plate is reduced, and the safety of the battery is improved.

Description

Negative plate and battery

Technical Field

The utility model relates to the technical field of batteries, in particular to a negative plate and a battery.

Background

The lithium ion battery is widely applied to the fields of digital products, electric automobiles, commercial vehicles, energy storage and the like, and the requirements on the energy density and the safety of the lithium ion battery are also higher and higher.

Currently, in order to improve the energy density of a battery, the single capacity of the battery is designed to be larger and larger, for example, a battery adopting a multi-tab winding structure, the single capacity can reach 100Ah to 300Ah, the length of an internal pole piece can reach 5 meters to 20 meters, and the thickness of a winding core can reach 10 millimeters to 30 millimeters. Therefore, the middle area of the electrode plate is soaked and is not good in contact, the lithium ion deintercalation resistance of the center area is larger than that of other areas, lithium precipitation easily occurs in the middle area of the negative electrode plate in a long-term circulation process, and the precipitated lithium dendrite continuously grows to puncture the diaphragm to cause internal short circuit of the contact of the positive electrode and the negative electrode, so that the battery is seriously ignited and exploded.

It can be seen that the battery in the prior art has a problem of poor safety.

Disclosure of Invention

The embodiment of the utility model provides a negative plate and a battery, which are used for solving the problem of poor safety of the battery in the prior art.

The embodiment of the utility model provides a negative electrode plate, which comprises a negative electrode current collector and a negative electrode active material layer coated on the negative electrode current collector, wherein the negative electrode active material layer sequentially comprises a first region, a second region and a third region along the width direction of the negative electrode plate, and the specific surface area of the second region is larger than the specific surface area of any one of the first region and the third region.

Optionally, the roughness of the second region is greater than the roughness of either of the first region and the third region.

Optionally, the ratio between the width of the second region and the width of the anode active material layer ranges from 1:10 to 1:2, and the width of the anode active material layer is the sum of the width of the first region, the width of the second region, and the width of the third region.

Optionally, the surface of the second area is formed with a three-dimensional pattern.

Optionally, the three-dimensional pattern is a pattern formed by a target device, and the target device is used for setting the three-dimensional pattern.

Optionally, the relief pattern includes at least one of a regular pattern and an irregular pattern.

Optionally, the shape of the three-dimensional pattern includes at least one of a dot shape, a linear bar shape, a diamond shape, a round hole shape, and a square shape.

Optionally, the negative electrode active material layer is disposed on two opposite side surfaces of the negative electrode current collector.

The embodiment of the utility model also provides a battery, which comprises the positive plate and the negative plate.

Optionally, the positive electrode sheet and the negative electrode sheet are wound.

In the embodiment of the utility model, the surface of the negative electrode current collector is coated with the negative electrode active material layer, the specific surface area of the second area (namely the middle area of the negative electrode plate) of the negative electrode active material layer is larger than the specific surface area of any one area (namely the edge area of the negative electrode plate) of the first area and the third area along the width direction of the negative electrode plate, the capillary adsorption action of electrolyte in the second area is enhanced, namely the liquid absorption capacity of the second area is larger than that of the first area and the third area, more lithium ions can be embedded in the larger specific surface area, and the lithium embedding capacity of the second area is improved. Therefore, the lithium precipitation condition in the middle area of the negative electrode plate is reduced, and the safety of the battery is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings used in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a negative plate according to an embodiment of the present utility model;

fig. 2 is a schematic structural view of a negative electrode sheet according to a comparative example of the present utility model.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the structures so used are interchangeable under appropriate circumstances such that embodiments of the utility model are capable of operation in sequences other than those illustrated or otherwise described herein, and that the objects identified by "first," "second," etc. are generally of a type and do not limit the number of objects, for example, the first object can be one or more.

The embodiment of the utility model provides a negative electrode sheet, as shown in fig. 1, comprising a negative electrode current collector and a negative electrode active material layer 10 coated on the negative electrode current collector, wherein the negative electrode active material layer sequentially comprises a first region 101, a second region 102 and a third region 103 along the width direction of the negative electrode sheet, and the specific surface area of the second region 102 is larger than the specific surface area of any one of the first region 101 and the third region 103.

In this embodiment, the surface of the negative electrode current collector is coated with the negative electrode active material layer 10, and the specific surface area of the second region 102 (i.e., the middle region of the negative electrode sheet) of the negative electrode active material layer is larger than the specific surface area of any one of the first region 101 and the third region 103 (i.e., the edge region of the negative electrode sheet), so that the capillary adsorption of the electrolyte in the second region 102 is enhanced, i.e., the liquid absorption capacity of the second region 102 is larger than the liquid absorption capacities of the first region 101 and the third region 103, and more lithium ions can be intercalated into the larger specific surface area, thereby improving the lithium intercalation capacity of the second region 102. Therefore, the lithium precipitation condition in the middle area of the negative electrode plate is reduced, and the safety of the battery is improved.

Optionally, the roughness of the second region 102 is greater than the roughness of either of the first region 101 and the third region 103.

In an example, textures (such as indentation, etching and the like) can be arranged in the second region 102, so that the roughness of the second region 102 is larger than that of any one of the first region 101 and the third region 103, and in this way, the absorption capacity of the second region 102 to electrolyte is further improved, so that the absorption capacity of the second region 102 is larger than that of the first region 101 and the third region 103, capillary absorption of the electrolyte is facilitated, the infiltration effect of the electrolyte in the middle region of the negative plate is enhanced, and the deintercalation resistance of lithium ions is reduced; and, the specific surface area of second region 102 is greater than the specific surface area of any one region in first region 101 and third region 103, has increased the embedded area of lithium ion in second region 102, has promoted the lithium intercalation ability of second region 102 to the condition that the middle region of negative pole piece was lithium-extracted has been reduced, the security of battery has been promoted.

Alternatively, the ratio 5 value between the width of the second region 102 and the width of the anode active material layer is in the range of 1:10 to 1:2, and the width of the anode active material layer may be the sum of the width of the first region 101, the width of the second region 102, and the width of the third region 103.

In an example, the width of the anode active material layer may be the sum of the width of the first region 101, the width of the second region 102, and the width of the third region 103, the width of the first region 101 and the width of the third region 103 may be equal, the second region 102 is located between the first region 101 and the third region 103, the ratio between the width of the anode sheet middle region, i.e., the second region 102, and the width of the anode active material layer may be in the range of 1:10 to 1:2, for example, the middle region width may be 1/10, 3/10, 1/2, or the like in the width of the anode sheet (i.e., the width of the anode active material layer) to increase the surface area and roughness of the anode sheet middle region such that the liquid absorbing capacity of the anode sheet middle region is greater than that of the other regions, the liquid absorbing capacity of the anode sheet middle region is increased

The infiltration effect of the electrolyte in the middle area of the negative plate is enhanced, and the deintercalation resistance of lithium ions is reduced; and more lithium ions can be embedded in the middle area of the negative plate, so that the lithium embedding capacity of the middle area of the negative plate is improved. The larger the ratio of the width of the second region 102 can be adjusted according to practical situations, so as to improve and improve lithium precipitation and reduce the influence on the performance of the negative electrode plate.

Optionally, the surface of the second region 102 is formed with a relief pattern 100.

In an example, the relief pattern 100 may be disposed in the second region 102 such that the specific surface area of the second region 102 is larger than the specific surface area of any one of the first region 101 and the third region 103, and/or the roughness of the second region 102 is larger than the roughness of any one of the first region 101 and the third region 103. In this way, compared with the first region 101 and the third region 103, the intercalation area of lithium ions in the second region 102 is increased, and the lithium intercalation capacity of the second region 102 is improved; and, make the second

The liquid absorption capacity of the area 102 is larger than that of the first area 101 and the third area 103, capillary absorption of electrolyte is facilitated, the wetting effect of the electrolyte in the second area 102 is enhanced, the deintercalation resistance of lithium ions is reduced, therefore, the lithium precipitation condition in the middle area of the negative electrode plate is reduced, and the safety of the battery is improved.

Alternatively, the relief pattern 100 may be a pattern formed via a target device for setting the relief pattern 100.

In one example, the target device may be an embossing device by which the electrode sheet is embossed or etched to form the relief pattern 100 in the second region 102 of the anode active material layer. For example, after the negative electrode active material layer is coated on one side surface of the negative electrode current collector, drying may be performed in an oven at 90 degrees celsius, compacting by a roll squeezer, and then embossing by an embossing device, thereby obtaining the negative electrode sheet provided with the three-dimensional pattern 100. Therefore, the process flow is simplified, the production cost is reduced, and the production efficiency is improved.

It should be noted that the target device may be other devices for printing textures, which is not limited herein.

In other alternative embodiments, the negative electrode active material layer is provided on both opposite side surfaces of the negative electrode current collector. The negative electrode active material layer can be coated on the two opposite side surfaces of the negative electrode current collector, and then is dried in an oven at 80-130 ℃, compacted by a roller press, and then a three-dimensional pattern 100 is formed at the position of the second region 102 by embossing equipment, wherein the second region 102 is the middle region of the two opposite sides of the negative electrode sheet, the liquid absorption capability of the second region 102 provided with the three-dimensional pattern 100 is further enhanced, the wetting effect of electrolyte in the middle region of the negative electrode sheet is enhanced, the deintercalation resistance of lithium ions is reduced, the intercalation area of the lithium ions in the second region 102 is further increased, the lithium intercalation capability of the second region 102 is improved, the lithium precipitation condition in the middle region of the negative electrode sheet is reduced, and the safety of the battery is improved.

The anode active material layer may include an anode active material, a binder, a thickener, and a conductive agent, the anode active material may be present in an amount of 85 to 98wt%, the binder may be present in an amount of 1 to 5%, the thickener may be present in an amount of 0.5 to 5%, and the conductive agent may be present in an amount of 0.5 to 5%.

Wherein, the negative electrode active material can be at least one of graphite, hard carbon, soft carbon and lithium titanate;

wherein the binder may be at least one of styrene-butadiene rubber and acrylic ester;

wherein the thickener can be at least one of sodium carboxymethyl cellulose and lithium carboxymethyl cellulose;

the conductive agent can be at least one of conductive carbon black, carbon nanotubes and graphene.

In one example, the negative electrode active material graphite, the binder styrene-butadiene rubber (SBR), the thickener sodium carboxymethyl cellulose (CMC) and the conductive agent carbon black (SP) are mixed and dispersed in deionized water to obtain a negative electrode slurry. And coating the negative electrode slurry on the two side surfaces of the negative electrode current collector, and coating the first surface and the second surface. Drying in an oven at 80-130 ℃, compacting by a roller press, and rolling by an embossing device at the position of a second region 102 to form a three-dimensional pattern 100, wherein the second region 102 is the middle region of the negative plate, so that the liquid absorption capacity of the second region 102 provided with the three-dimensional pattern 100 is enhanced, the infiltration effect of electrolyte in the middle region of the negative plate is enhanced, and the deintercalation resistance of lithium ions is reduced; and more lithium ions can be embedded in the middle area of the negative plate, so that the lithium embedding capacity of the middle area of the negative plate is improved.

Wherein the three-dimensional pattern 100 includes at least one of a regular pattern and an irregular pattern.

Regular patterns, such as at least one of a shape, a linear shape, a triangle, a diamond, a round hole shape and a square shape, or other irregular patterns, can be arranged on the roller of the embossing equipment according to actual conditions.

The specific surface area and roughness of the second region 102 may be varied according to the shape of the pattern and/or the number of patterns

The liquid absorption capacity of the middle area of the negative electrode plate is larger than that of other areas by row adjustment, so that the infiltration effect of electrolyte in the middle area of the negative electrode plate is enhanced, and the deintercalation resistance of lithium ions is reduced; and more lithium ions can be embedded in the middle area of the negative plate, so that the lithium embedding capacity of the middle area of the negative plate is improved, the lithium precipitation condition of the middle area of the negative plate is reduced, and the safety of the battery is improved.

The embodiment of the utility model also provides a battery, which comprises the positive plate and the negative plate.

In this embodiment, the negative electrode sheet, the positive electrode sheet, the separator, the electrolyte, and the casing are assembled, and the lithium ion battery is manufactured through the steps of formation, air extraction, sealing, sorting, and the like. The positive plate and the negative plate can be wound to improve the energy density of the battery.

The batteries of examples 1 to 3, and comparative example 1 were subjected to a low-temperature charging performance test, and the negative electrode lithium deposition was anatomically observed.

Example 1:

preparing a negative plate: the selected negative electrode active material is graphite, and the content is 95%; the binder is SBR with 2 percent; the thickener is CMC, the content is 1%; the conductive agent is SP, and the content is 2%. Graphite, SBR, CMC and SP are mixed and dispersed in deionized water to obtain negative electrode slurry. And coating the negative electrode slurry on the two side surfaces of the negative electrode current collector, and coating the first surface and the second surface. Drying in an oven at 90deg.C

Drying, compacting by a roller press, and rolling by an embossing device at the position of a second area 102 to form a three-dimensional pattern 100, wherein the second area 102 is the middle area of the negative plate, and the ratio of the second area 102 in the width of the electrode plate is 1/10; the shape of the relief pattern 100 is diamond-shaped. The design negative electrode sheet P1 is obtained.

Preparation of a positive plate: the selected positive electrode active material is ternary nickel cobalt manganese (NCM 523), and the content is 96%; the binder is polyvinylidene fluoride (PVDF) with the content of 2 percent; the conductive agent is conductive carbon black containing

The amount was 2%. NCM523, PVDF, and conductive carbon black were dispersed in N-methylpyrrolidone to give a uniform positive electrode active material slurry. And coating the prepared positive electrode active material slurry on the surfaces of two sides of the aluminum foil, drying, and compacting the pole piece and a roller press to obtain the positive electrode piece.

Preparation of a battery: and assembling the negative plate P1 with the positive plate, the diaphragm, the electrolyte and the shell, performing the working procedures of formation, air extraction, sealing, sorting and the like to prepare the lithium ion battery, performing low-temperature charging performance test on the battery, and dissecting and observing the lithium precipitation condition of the negative electrode. This is designated example 1.

Example 2:

preparing a negative plate: the selected negative electrode active material is graphite, and the content is 95%; the binder is SBR with 2 percent; the thickener is CMC, the content is 1%; the conductive agent is SP, and the content is 2%. Graphite, SBR, CMC and SP are mixed and dispersed in deionized water to obtain negative electrode slurry. And coating 5 the negative electrode slurry on the two side surfaces of the negative electrode current collector, and coating the first surface and the second surface. Drying in an oven at 90 ℃, compacting by a roller press, and rolling by an embossing device at the position of a second area 102 to form a three-dimensional pattern 100, wherein the second area 102 is the middle area of the negative plate, and the second area 102 has a ratio of 3/10 in the width of the pole plate; the shape of the relief pattern 100 is diamond-shaped. The design negative electrode sheet P2 is obtained.

Preparation of a positive plate: the selected positive electrode active material is ternary nickel cobalt manganese (NCM 523), and the content is 96%; the binder is polyvinylidene fluoride (PVDF) with the content of 2 percent; the conductive agent is conductive carbon black, and the content is 2%. NCM523, PVDF, and conductive carbon black were dispersed in N-methylpyrrolidone to give a uniform positive electrode active material slurry. And coating the prepared positive electrode active material slurry on the surfaces of two sides of the aluminum foil, drying, and compacting the pole piece and a roller press to obtain the positive electrode piece.

Preparation of a battery: and assembling the negative plate P2 with the positive plate, the diaphragm, the electrolyte and the shell, performing the working procedures of formation, air extraction, sealing, sorting and the like to prepare the lithium ion battery, performing low-temperature charging performance test on the battery, and dissecting and observing the lithium precipitation condition of the negative electrode. Is described as example 2.

Example 3:

preparing a negative plate: the selected negative electrode active material is graphite, and the content is 95%; the binder is SBR

The content is 2%; the thickener is CMC, the content is 1%; the conductive agent is SP, and the content is 2%. Graphite, SBR, CMC and SP are mixed and dispersed in deionized water to obtain negative electrode slurry. And coating the negative electrode slurry on the two side surfaces of the negative electrode current collector, and coating the first surface and the second surface. Drying in an oven at 90 ℃, compacting by a roller press, and rolling by an embossing device at the position of a second area 102 to form a three-dimensional pattern 100, wherein the second area 102 is the middle area of the negative plate, and the second area 102 has a ratio of 1/2 in the width of the pole plate; the shape of the relief pattern 100 is diamond-shaped. The design negative electrode sheet P3 is obtained.

Preparation of a positive plate: the selected positive electrode active material is ternary nickel cobalt manganese (NCM 523), and the content is 96%; the binder is polyvinylidene fluoride (PVDF) with the content of 2 percent; the conductive agent is conductive carbon black, and the content is 2%. NCM523, PVDF, and conductive carbon black were dispersed in N-methylpyrrolidone to give a uniform positive electrode active material slurry. And coating the prepared positive electrode active material slurry on the surfaces of two sides of the aluminum foil, drying, and compacting the pole piece and a roller press to obtain the positive electrode piece.

Preparation of a battery: and assembling the negative plate P3 with the positive plate, the diaphragm, the electrolyte and the shell, performing the working procedures of formation, air extraction, sealing, sorting and the like to prepare the lithium ion battery, performing low-temperature charging performance test on the battery, and dissecting and observing the lithium precipitation condition of the negative electrode. Is described as example 3.

Comparative example 1:

the main difference from example 1 is that the negative electrode sheet was prepared without embossing treatment, i.e., the second region 102 was not formed with the relief pattern 100. The negative electrode slurry is coated on the two side surfaces of the negative electrode current collector, and the first surface is coated and the second surface is coated. Drying in an oven at 90 ℃, and compacting by a roller press to obtain a designed negative plate P0, as shown in figure 2. The rest steps are consistent, the battery is subjected to low-temperature charging performance test, and the lithium precipitation condition of the negative electrode is anatomically observed. Is designated as comparative example 1.

The batteries prepared in the above examples 1 to 3 and comparative example 1 were subjected to low-temperature 0 degree 1C charge, 5 degree 2.5C charge, 15 degree 5C charge cycle 30 cycles of test, voltage range 2.5V to 4.2V, full charge after cycle, and after 24 hours of rest, the negative electrode lithium precipitation was observed by anatomic observation, and the statistical data are shown in table 1 below:

table 1:

by observing the schemes of the embodiments 1 to 3, after the stereoscopic pattern 100 is set for the second region 102 of the negative electrode sheet and the width of the second region 102 is set to be in the ratio range of 1/10 to 1/2 of the whole width of the electrode sheet, the obtained battery does not have the lithium precipitation in the middle region of the negative electrode sheet under different low-temperature environments. While comparative example 1 showed a different degree of lithium evolution in the packet test. It can be seen that by arranging the three-dimensional pattern 100 in the second region 102, the liquid absorption capacity of the second region 102 is greater than that of the first region 101 and the third region 103, and the adsorption capacity of the middle region of the negative electrode sheet to the electrolyte is enhanced; and more lithium ions can be embedded in the three-dimensional pattern 100, so that the lithium embedding capability of the second region 102 is improved. Therefore, the lithium precipitation condition in the middle area of the negative electrode plate is reduced, and the safety of the battery is improved.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of the present utility model is not limited to performing the functions in the order discussed, but may also include performing the functions in a substantially simultaneous manner or in an opposite order depending on the functions involved, e.g., the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

The embodiments of the present utility model have been described above with reference to the accompanying drawings, but the present utility model is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present utility model and the scope of the claims, which are to be protected by the present utility model.

Claims (10)

1. The negative electrode sheet is characterized by comprising a negative electrode current collector and a negative electrode active material layer coated on the negative electrode current collector, wherein the negative electrode active material layer sequentially comprises a first region, a second region and a third region along the width direction of the negative electrode sheet, and the specific surface area of the second region is larger than the specific surface area of any one of the first region and the third region.

2. The negative electrode sheet according to claim 1, wherein the roughness of the second region is greater than the roughness of either one of the first region and the third region.

3. The negative electrode sheet according to claim 1, wherein a ratio between the width of the second region and the width of the negative electrode active material layer is in a range of 1:10 to 1:2, the width of the negative electrode active material layer being a sum of the width of the first region, the width of the second region, and the width of the third region.

4. The negative electrode sheet according to claim 1, wherein the surface of the second region is formed with a three-dimensional pattern.

5. The negative electrode sheet according to claim 4, wherein the three-dimensional pattern is a pattern formed via a target device for setting the three-dimensional pattern.

6. The negative plate according to claim 4, wherein the three-dimensional pattern includes at least one of a regular pattern and an irregular pattern.

7. The negative electrode sheet of claim 4, wherein the shape of the relief pattern comprises at least one of a dot shape, a linear shape, a diamond shape, a round hole shape, a square shape.

8. The negative electrode sheet according to any one of claims 1 to 7, characterized in that both side surfaces of the negative electrode current collector facing away from each other are provided with the negative electrode active material layer.

9. A battery comprising a positive electrode sheet and the negative electrode sheet according to any one of claims 1 to 8.

10. The battery of claim 9, wherein the positive and negative electrode sheets are wound.

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