CN116632163A

CN116632163A - Pole piece, preparation method thereof, battery monomer, battery and electricity utilization device

Info

Publication number: CN116632163A
Application number: CN202310904929.6A
Authority: CN
Inventors: 吴凯; 吉星
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-07-24
Filing date: 2023-07-24
Publication date: 2023-08-22
Anticipated expiration: 2043-07-24
Also published as: CN116632163B

Abstract

A pole piece and a preparation method thereof, a battery monomer, a battery and an electricity utilization device belong to the technical field of batteries. The pole piece comprises a current collector, a first coating and an active material layer, wherein the current collector, the first coating and the active material layer are sequentially arranged along the thickness direction of the pole piece; the current collector comprises a main body part and a tab, the tab extends from a first end of the main body part, the first end is one end of the main body part along a first direction, the main body part comprises a first coating area and a second coating area, and the first coating area is arranged between the second coating area and the tab; the active material layer is arranged on the surfaces of the first coating area and the second coating area; at least a portion of the first coating is disposed on a surface of the first coating region, the first coating including a thermoplastic polymer, a conductive agent, and a binder. The technical scheme of the application is beneficial to improving the energy density of the battery monomer and the performance of the pole piece.

Description

Pole piece, preparation method thereof, battery monomer, battery and electricity utilization device

Technical Field

The application relates to the technical field of batteries, in particular to a pole piece, a preparation method thereof, a battery monomer, a battery and an electric device.

Background

With the increasing increase of environmental pollution, the new energy industry is receiving more and more attention. In the new energy industry, battery technology is an important factor in its development.

The development of battery technology requires consideration of various design factors such as energy density, cycle life, reliability, and the like. The design of the pole piece in the battery cell is critical to the energy density of the battery cell, so how to provide a pole piece to improve the energy density of the battery cell and the performance of the pole piece is a technical problem to be solved.

Disclosure of Invention

The present application has been made in view of the above problems, and an object thereof is to provide a pole piece that improves the energy density of a battery cell and the performance of the pole piece.

In order to achieve the above purpose, the application provides a pole piece, a preparation method thereof, a battery cell, a battery and an electric device.

In a first aspect, a pole piece is provided, including a current collector, a first coating layer and an active material layer sequentially disposed along a thickness direction of the pole piece; the current collector comprises a main body part and a tab, wherein the tab extends from a first end of the main body part, the first end is one end of the main body part along a first direction, the main body part comprises a first coating area and a second coating area, and the first coating area is arranged between the second coating area and the tab; the active material layer is arranged on the surfaces of the first coating area and the second coating area; at least a portion of the first coating is disposed on a surface of the first coating zone, the first coating including a thermoplastic polymer, a conductive agent, and a binder.

In the embodiment of the application, the active material layer is positioned on the surfaces of the first coating region and the second coating region, so that the energy density of the battery cell is improved compared with the active material layer which is positioned on the surface of the second coating region only. The first coating is positioned between the current collector and the active material layer along the thickness direction of the pole piece, so that the risk of falling off of the active material layer can be reduced in the process of cutting the current collector to prepare the pole lug, and the performance of the pole piece can be improved; the first coating comprises a thermoplastic polymer, a conductive agent and a binder, so that the thermoplastic polymer and the conductive agent can be bonded on the surface of the current collector, the exposed end face of the cut current collector has certain insulativity, and the current collector provided with the first coating has certain conductivity, thereby being beneficial to improving the comprehensive performance of the pole piece. Therefore, the technical scheme of the application is beneficial to improving the energy density of the battery monomer and the performance of the pole piece.

In one possible implementation, at least part of the first coating is disposed on surfaces on both sides of the first coating region. Thus, the surfaces of the two sides of the first coating area are provided with the first coating, which is beneficial to improving the symmetry of the pole piece and facilitating the application of the pole piece.

In one possible implementation, at least part of the first coating is disposed on a surface of one side of the first coating region. Therefore, the first coating is coated on the surface of one side of the first coating area, which is beneficial to simplifying the preparation process of the pole piece and accelerating the production rhythm.

In one possible implementation, the first coating is disposed on a surface of the second coating region and a surface of the first coating region. Thus, both the surface of the first coating zone and the surface of the second coating zone are provided with a first coating, so to speak, both the surface of the body portion is provided with a first coating. Thus, the manufacturing process of the pole piece is facilitated to be simplified, and the production rhythm is quickened.

In one possible implementation, the thermoplastic polymer has a mass content a of 30wt% to 40wt%, the conductive agent has a mass content B of 30wt% to 40wt%, and the binder has a mass content C of 20wt% to 40wt%, based on the total mass of the first coating.

In the technical scheme, the mass content A of the thermoplastic polymer is 30-40 wt%, so that a uniform and compact insulating layer is formed on the exposed end face of the cut current collector; the mass content B of the conductive agent is 30-40 wt%, so that the pole piece has proper surface resistance and proper conductivity; the mass content C of the binder is 20-40 wt%, so that the first coating and the current collector have proper binding force, and the risk of the first coating falling off from the current collector can be reduced.

In one possible implementation manner, a ratio of the surface resistance R1 of the tab to the surface resistance R2 of the current collector provided with the first coating is r1:r2 of 1 to 1.3. Thus, after the first coating is arranged, the pole piece has proper resistance, so that the pole piece has proper conductivity, and the influence on the battery cell caused by overlarge resistance of the pole piece can be reduced.

In one possible implementation, the adhesion force F between the first coating and the current collector is 20N/m-100N/m; optionally, F is 55N/m to 92N/m. In this way, having a suitable adhesion between the first coating and the current collector, the risk of the first coating falling off the current collector can be reduced.

In one possible implementation, the total thickness d1 of the first coating is 2 μm to 14 μm; optionally, d1 is 4 μm to 8 μm.

In the technical scheme, under the condition that the total thickness d1 of the first coating is not smaller than 2 mu m, in the process of cutting the current collector provided with the first coating, more thermoplastic polymers in the first coating are contained, so that more thermoplastic polymers can flow to burrs and exposed end faces of the current collector after being heated, and the exposed end faces and burrs are uniformly and compactly coated; in the case that the total thickness d1 of the first coating layer is not more than 14 μm, it is advantageous to reduce the space occupied by the first coating layer and to increase the energy density of the battery cell.

In one possible implementation, the pole piece further includes a first insulating layer disposed at an end face of the body portion at the first end. Thus, the first insulating layer can cover the end face of the main body part at the first end and burrs generated by cutting, so that the risk of short circuit caused by overlapping the end face and the burrs with electrodes with opposite polarities can be reduced.

In one possible implementation manner, the thickness d2 of the first insulating layer is 10 nm-200 nm. In this way, the first insulating layer can better cover burrs and exposed end surfaces with a smaller thickness. Optionally, the thickness d2 of the first insulating layer is 50 nm-200 nm. Thus, the coating effect on burrs and end faces is further improved.

In one possible implementation, the material of the first insulating layer is the same as the material of the thermoplastic polymer in the first coating layer. Thus, the preparation steps of the pole piece are simplified, and the production rhythm is quickened.

In one possible implementation, the thermoplastic polymer of the first insulating layer is a film layer. Thus, the first insulating layer is formed after the thermoplastic polymer in the first coating layer is melted and resolidified. Thus, the manufacturing steps of the pole piece are simplified, and the first insulating layer can be formed while cutting.

In one possible implementation, the resistance R3 of the first insulating layer satisfies: r3 is more than or equal to 1Ω; alternatively, R3 satisfies: r3 is more than or equal to 800 omega. The resistance of the first insulating layer satisfies the above conditions, and thus, the risk of short-circuiting of the battery cells due to overlap of the end surfaces with the electrodes having opposite polarities can be reduced.

In one possible implementation, the thermoplastic polymer has a melting point T of 100 ℃ to 200 ℃; optionally, the thermoplastic polymer comprises: at least one of polystyrene, polyolefin, polyimide, polyester, polyphenylene sulfide, polyamide, copolymer of butyl acrylate and ethyl methacrylate, and their respective modified polymers. Alternatively, the polyamide comprises a polyaramid.

In the technical scheme, the thermoplastic polymer has a proper melting point, and under the action of heat generated by cutting in the process of cutting the current collector provided with the first coating, the thermoplastic polymer is changed from a solid state into a flowing state, and the flowing thermoplastic polymer can flow to the end face of the exposed current collector after cutting and the burr generated by cutting, so that the first insulating layer is convenient to prepare. By adopting the thermoplastic polymer, uniform and compact coating is formed on the end face and the burr of the cut bare current collector.

In one possible implementation, the binder includes: at least one of polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-polyacrylonitrile copolymer, polyether acrylate, polyacrylic acid, polyacrylonitrile, gelatin, chitosan and sodium alginate. The adhesive has good adhesive property, and is convenient for bonding the thermoplastic polymer to the surface of the current collector.

In one possible implementation, the conductive agent comprises conductive carbon; optionally, the conductive carbon comprises at least one of carbon black, ketjen black, acetylene black, superconducting carbon, carbon nanofibers, carbon nanotubes, and graphene. The conductive carbon has good conductive performance, does not react with the thermoplastic polymer, and is used as a conductive agent, thereby being beneficial to improving the conductive performance of the first coating.

In one possible implementation, the pole piece comprises a positive pole piece; optionally, the current collector comprises aluminum foil. Therefore, the risk of overlapping the positive pole piece and the negative pole piece is reduced, and the reliability of the battery cell is improved. In addition, the risk of overlap joint generation of lithium dendrites precipitated by the positive electrode plate and the negative electrode plate is reduced. The current collector comprises aluminum foil, so that the current collector has a simpler structure, and is beneficial to simplifying the preparation process of the current collector.

In one possible implementation, the positive electrode sheet includes a positive electrode active material including LiNi _0.8 Co _0.1 Mn _0.1 O ₂ 。

In one possible implementation, the current collector comprises a metal foil or a composite current collector; optionally, the metal foil comprises aluminum foil or copper foil; optionally, the composite current collector comprises: a polymer material base layer and a metal layer positioned on at least one surface of the polymer material base layer; optionally, the current collector comprises aluminum foil. In this way, it is convenient to select a suitable current collector according to the actual needs. Under the condition that the current collector comprises aluminum foil, the pole piece is an anode pole piece, so that the risk of lap joint of the anode pole piece and the cathode pole piece is reduced, and the reliability of the battery cell is improved. In addition, the risk of overlap joint generation of lithium dendrites precipitated by the positive electrode plate and the negative electrode plate is reduced.

In a second aspect, a method for preparing a pole piece is provided, including: providing a current collector; applying a first slurry to a first application region of the current collector to form a first coating, the first slurry comprising a thermoplastic polymer emulsion, a conductive agent, and a binder; coating a second slurry on the first and second coating regions of the current collector to form an active material layer, the second slurry including an active material; and cutting the current collector provided with the first coating layer and the active material layer along a cutting line, wherein at least part of the cutting line is arranged in the first coating area.

In the technical scheme, the active material layers are arranged in the first coating area and the second coating area of the current collector, so that the energy density of the battery cell is improved compared with the case that the active material layers are coated only in the first coating area; furthermore, by the provision of the first coating layer, the risk of the active substance layer falling off during the cutting process can be reduced. The first coating comprises thermoplastic polymer emulsion, so that after the current collector is cut, a first insulating layer is formed on the exposed end face of the current collector after the current collector is cut, and the short circuit risk caused by overlapping of the end face and an electrode with opposite polarity can be reduced; the first coating comprises a conductive agent, and the first coating and the pole piece have certain conductivity; the first coating includes a binder therein to facilitate bonding of the conductive agent and the thermoplastic polymer to the surface of the current collector. Therefore, the battery monomer prepared by the method has higher energy density, and meanwhile, the pole piece has better performance.

In one possible implementation, the method further includes: the first slurry is coated on the second coating region of the current collector to form the first coating layer. Thus, the manufacturing process of the pole piece is facilitated to be simplified, and the production rhythm is quickened.

In one possible implementation, the thermoplastic polymer emulsion has a mass content a of 30wt% to 40wt%, the conductive agent has a mass content B of 30wt% to 40wt%, and the binder has a mass content C of 20wt% to 40wt%, based on the total mass of the first slurry.

In one possible implementation, the total thickness d1 of the first coating layer is 2 μm to 14 μm.

In one possible implementation, the viscosity of the first slurry is 50 mPa-s to 500 mPa-s. In this way, the application of the first slurry is facilitated.

In one possible implementation, the binder includes: at least one of polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-polyacrylonitrile copolymer, polyether acrylate, polyacrylic acid, polyacrylonitrile, gelatin, chitosan and sodium alginate.

In one possible implementation, the conductive agent comprises conductive carbon; optionally, the conductive carbon comprises at least one of carbon black, ketjen black, acetylene black, superconducting carbon, carbon nanofibers, carbon nanotubes, and graphene.

In one possible implementation, the applying the first slurry in the first application region of the current collector to form a first coating includes: and coating the first slurry on the first coating area of the current collector by means of gravure coating to form the first coating. The first coating with smaller thickness is convenient to prepare by adopting a gravure coating mode.

In one possible implementation, cutting the current collector provided with the first coating layer and the active material layer along a cut line includes: and controlling a laser processing tool, and cutting the current collector provided with the first coating and the active material layer along the cutting line.

According to the technical scheme, the current collector is cut through the laser, more heat can be generated in the cutting process, and the thermoplastic polymer in the first coating is changed into a flowing state to flow to the end face, so that the first insulating layer is formed conveniently.

In a third aspect, there is provided a battery cell comprising a pole piece according to the first aspect and any one of the possible implementations, and/or a pole piece prepared according to the second aspect and any one of the possible implementations.

In a fourth aspect, there is provided a battery comprising the battery cell of the third aspect.

In a fifth aspect, there is provided an electrical device comprising the battery of the fourth aspect.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of a pole piece of an embodiment of the present application before processing a tab;

FIG. 2 is a schematic illustration of a pole piece according to an embodiment of the present application;

FIG. 3 is a cross-sectional view taken along the direction A-A in FIG. 2;

FIG. 4 is a cross-sectional view taken along the B-B direction in FIG. 2;

FIG. 5 is a cross-sectional view of a pole piece of another embodiment of the present application taken along the A-A direction;

FIG. 6 is a cross-sectional view of a pole piece of another embodiment of the present application taken along the B-B direction;

FIG. 7 is a cross-sectional view of a pole piece according to yet another embodiment of the present application taken along the A-A direction;

FIG. 8 is a cross-sectional view of a pole piece of yet another embodiment of the present application taken along the B-B direction;

FIG. 9 is a schematic illustration of a method of making a pole piece according to an embodiment of the present application;

FIG. 10 is a schematic diagram of a battery cell according to an embodiment of the application;

FIG. 11 is a schematic view of a battery according to an embodiment of the application;

fig. 12 is a schematic diagram of an electric device according to an embodiment of the application.

Reference numerals:

1: a pole piece; 124: cutting lines; 10: a current collector; 11: an active material layer; 121: a first coating; 131: a first insulating layer; 101: a main body portion; 102: a tab; 1011: a first coating zone; 1012: a second coating zone; 1011a: an end face; 3: a battery cell; 31: a housing; 32: an end cap assembly; 33: an electrode assembly; 34: a current collecting member; 322: an electrode terminal; 5: a battery; 6: and (5) an electric device.

Detailed Description

The detailed description of the drawings appropriately refers to the accompanying drawings, and specifically discloses the pole piece, the preparation method thereof, the battery cell, the battery and the embodiment of the electric device. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.

The "range" disclosed herein is defined in terms of lower and upper limits, with the given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.

All embodiments of the application and alternative embodiments may be combined with each other to form new solutions, unless otherwise specified.

All technical features and optional technical features of the application may be combined with each other to form new technical solutions, unless specified otherwise.

All the steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise specified. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.

The development of battery technology has been accompanied by consideration of various design factors such as energy density, cycle life, discharge capacity, charge-discharge rate, reliability, etc. The design of the pole pieces in the battery cells is critical to the energy density of the battery cells. The pole piece comprises a current collector and an active material layer, wherein the current collector comprises a main body part and a pole lug protruding out of the main body part. In order to reduce the risk of the active material layer falling off during the process of cutting the current collector to prepare the tab, it is common to provide an active material layer on a part of the surface of the main body portion and an insulating layer on the other part of the surface of the main body portion. In this way, the active material layer is not cut in the cutting process, and the risk of falling off of the active material layer can be reduced. However, the insulating layer occupies a certain space, resulting in a certain waste of the space of the battery cell, which is disadvantageous for improving the energy density of the battery cell.

In view of this, the present application provides a pole piece comprising a current collector, a first coating and an active material layer. The current collector comprises a main body part and a tab, an active material layer is arranged on the surface of the main body part, a first coating layer is arranged in a first coating area of the main body part, and the first coating layer is arranged between the current collector and the active material layer along the thickness direction of the pole piece. Thus, the active material layer is arranged on the surface of the main body part, which is beneficial to improving the energy density of the battery cell; meanwhile, the influence of cutting on the active material layer can be reduced due to the arrangement of the first coating, so that the risk of falling of the active material layer can be reduced, and the performance of the pole piece is improved. Therefore, the technical scheme of the application can improve the performance of the pole piece while improving the energy density of the battery monomer.

Pole piece

Fig. 1 is a schematic view of a pole piece according to an embodiment of the present application before processing a tab, fig. 2 is a schematic view of a pole piece according to an embodiment of the present application, fig. 3 is a sectional view along A-A in fig. 2, and fig. 4 is a sectional view along B-B in fig. 2.

Referring to fig. 1 and 2, fig. 1 is a schematic view of a pole piece before processing the pole lug, and fig. 2 is a schematic view of a pole piece after processing the pole lug. As shown in fig. 1, the black dotted line is a cut line 124 for cutting the tab, and after cutting along the cut line 124, the pole piece 1 shown in fig. 2 is obtained.

As shown in fig. 1 to 4, the electrode sheet 1 includes a current collector 10, a first coating layer 121, and an active material layer 11, which are sequentially disposed in the thickness direction of the electrode sheet 1.

The thickness direction of the pole piece 1 may be the z direction in fig. 3 and 4. It should be noted that the thickness direction of the pole piece 1 and the thickness direction of the current collector 10 in the embodiment of the present application are the same direction.

The current collector 10 includes a main body portion 101 and a tab 102, the tab 102 extending from a first end of the main body portion 101, the first end of the main body portion 101 being an end of the main body portion 101 in a first direction.

The first direction is parallel to the plane in which the current collector 10 is located, and is a direction in which the tab 102 protrudes with respect to the main body portion 101. For example, the first direction is the y-direction in fig. 2.

The main body part 101 includes a first coating region 1011 and a second coating region 1012, and the first coating region 1011 is disposed between the second coating region 1012 and the tab 102.

For example, as shown in connection with fig. 3 and 4, the first coating region 1011 and the second coating region 1012 are connected, and the first coating region 1011 extends from the second coating region 1012 in the first direction.

The active material layer 11 is disposed on the surfaces of the first and second coating regions 1011 and 1012. Compared with the active material layer 11 only arranged on the surface of the second coating region 1012 of the main body 101, the active material layer 11 is arranged on the surfaces of the first coating region 1011 and the second coating region 1012, and the active material in the pole piece 1 is increased, so that the volume energy density of the battery cell is improved.

The current collector 10 has two surfaces opposite in the thickness direction thereof, and the active material layer 11 may be provided on at least one of the two opposite surfaces in the thickness direction of the body portion 101 of the current collector 10. For example, as shown in fig. 3 and 4, both surfaces of the current collector 10, which are opposite in the thickness direction thereof, are provided with active material layers 11.

At least a portion of the first coating 121 is disposed on a surface of the first coating region 1011, the first coating 121 including a thermoplastic polymer, a conductive agent, and a binder.

At least a portion of the first coating 121 is disposed on the surface of the first coating region 1011, and may include the following: the first coating layer 121 is disposed only on the surface of the first coating region 1011; alternatively, the first coating 121 is disposed on the surface of the first coating region 1011 and the surface of the second coating region 1012.

The first coating region 1011 has opposite surfaces in the thickness direction of the pole piece 1. The first coating layer 121 may be provided on one of the two surfaces or may be provided on both surfaces.

The first coating layer 121 is closer to the current collector 10 than the active material layer 11, so that most of heat generated during cutting can be absorbed by the first coating layer 121 during cutting, and thus the influence of the heat generated during cutting on the active material layer 11 can be reduced, and the risk of falling off the active material layer 11 can be reduced. In addition, there is no need to provide an additional region on the main body 101 and an insulating layer on the additional region to reduce the falling of the active material layer 11, so that the space occupied by the pole piece 1 can be further reduced, and the volume energy density of the battery cell can be improved.

The first coating 121 includes a thermoplastic polymer, and the thermoplastic polymer in the first coating 121 may change from a solid state to a fluid state when heated under certain conditions, so that in the process of cutting the current collector 10 provided with the first coating 121, the fluid thermoplastic polymer may flow to burrs generated by cutting and exposed end surfaces after cutting, and after the temperature is reduced, the fluid thermoplastic polymer is solidified at the burrs and the exposed end surfaces to cover the burrs and the exposed end surfaces, thereby reducing the risk of short circuit caused by overlapping of the burrs and the exposed end surfaces with electrodes with opposite polarities, and the exposed end surfaces of the pole pieces may have certain insulation. In addition, the thermoplastic polymer absorbs more heat when heated and melts, so that less heat is transferred to the active material layer 11, the binder in the active material layer 11 is not thermally decomposed, and the risk of the active material layer 11 falling off from the current collector 10 is reduced.

Thermoplastic polymers, which may be referred to as polymers that soften after heating, solidify upon cooling, and can be softened again. For example, when heated to a certain temperature, the thermoplastic polymer changes from solid particles to a flowable state, and when cooled, it can become a layered or film layered thermoplastic polymer.

The maximum particle size of the thermoplastic polymer may be less than the thickness of the first coating layer 121 to facilitate the preparation of the first coating layer 121. The maximum particle size of the thermoplastic polymer of the embodiments of the present application may be set according to actual needs.

The first coating 121 includes a conductive agent. Since the thermoplastic polymer is an insulating substance, the conductive agent is added to the first coating 121, so that the influence of the thermoplastic polymer on the pole piece 1 can be reduced, and the pole piece 1 can have certain conductivity.

The first coating 121 includes an adhesive by which the thermoplastic polymer and the conductive agent may be adhered to the surface of the current collector 10, reducing the risk of the first coating 121 falling off the current collector 10.

In the embodiment of the present application, the active material layer 11 is positioned on the surfaces of the first and second coating regions 1011 and 1012, which is advantageous in improving the energy density of the battery cell compared to the portion of the active material layer 11 positioned on the surface of the body part 101. Along the thickness direction of the pole piece 1, the first coating 121 is positioned between the current collector 10 and the active material layer 11, so that the risk of falling off of the active material layer 11 can be reduced in the process of cutting the current collector 10 to prepare the tab 102, and the performance of the pole piece 1 can be improved; the first coating 121 includes a thermoplastic polymer, a conductive agent and a binder, so that the thermoplastic polymer and the conductive agent can be adhered to the surface of the current collector 10, the exposed end surface of the cut current collector 10 has a certain insulation property, and the current collector 10 provided with the first coating 121 has a certain conductivity, thereby being beneficial to improving the performance of the pole piece. Therefore, the technical scheme of the application is beneficial to improving the energy density of the battery monomer and the performance of the pole piece.

In some embodiments, at least a portion of the first coating 121 is disposed on surfaces of both sides of the first coated region 1011.

The first coating region 1011 has opposite surfaces along opposite sides of the thickness direction of the pole piece 1.

The surfaces of both sides of the first coating region 1011 are provided with the first coating 121 in the thickness direction of the pole piece 1. For example, the first coating 121 on the surfaces of both sides of the first coating region 1011 has the same thickness, so that the pole piece 1 has better symmetry.

Alternatively, the first coating 121 on the surfaces of both sides of the first coating region 1011 have different thicknesses.

In the above embodiment, the surfaces on both sides of the first coating region 1011 are provided with the first coating 121, which is beneficial to improving the symmetry of the pole piece 1 and facilitating the application of the pole piece 1.

In some embodiments, the first coating 121 is disposed on a surface of one side of the first coating region 1011.

In the above embodiment, the first coating 121 is coated on only one side of the first coating region 1011, which is advantageous in simplifying the manufacturing process of the pole piece 1 and accelerating the production rhythm.

Alternatively, the surface of the first coating region 1011 is provided with the first coating 121 and the surface of the second coating region 1012 is not provided with the first coating 121. In this way, the material of the first coating 121 required for preparing the pole piece 1 is advantageously reduced, and the production cost is advantageously reduced.

Fig. 5 is a cross-sectional view of a pole piece according to another embodiment of the present application along A-A direction, and fig. 6 is a cross-sectional view of a pole piece according to another embodiment of the present application along B-B direction. In some embodiments, as shown in conjunction with fig. 5 and 6, the first coating 121 is disposed on the surface of the second coating region 1012 and the surface of the first coating region 1011.

The surface of the first coating region 1011 and the surface of the second coating region 1012 are each provided with the first coating layer 121, so to speak, the surface of the main body portion 101 is each provided with the first coating layer 121.

The first coating layer 121 may be disposed on both surfaces of the first and second coating regions 1011 and 1012 opposite in the thickness direction of the pole piece 1, for example, as shown in fig. 5 and 6.

Fig. 7 is a cross-sectional view of a pole piece according to yet another embodiment of the present application along A-A, and fig. 8 is a cross-sectional view of a pole piece according to yet another embodiment of the present application along B-B. As shown in conjunction with fig. 7 and 8, the first coating layer 121 is provided on one of the two surfaces of the second coating region 1012 that are opposite in the thickness direction of the pole piece 1. In this case, the active material layer 11, the current collector 10, the first coating layer 121, and the active material layer 11 are sequentially arranged in the thickness direction of the electrode sheet 1.

As an example, the pole piece 1 is prepared by the following method. A current collector 10 having a large area is provided, a first coating layer 121 and an active material layer 11 are coated on the current collector 10, and then the current collector 10 provided with the first coating layer 121 and the active material layer 11 may be cut into a plurality of electrode sheets. Applying the first coating 121 to the body portion 101 is advantageous in that the number of cuts is reduced, and more pole pieces 1 can be cut out with fewer cuts, than applying the first coating 121 only to the first coating region 1011.

In the above embodiment, the surfaces of the first coating region 1011 and the second coating region 1012 are both provided with the first coating 121, which is beneficial to simplifying the preparation process of the pole piece 1 and accelerating the production rhythm.

In some embodiments, the thermoplastic polymer is present in an amount of 30wt% to 40wt%, the conductive agent is present in an amount of 30wt% to 40wt%, and the binder is present in an amount of 20wt% to 40wt%, based on the total mass of the first coating 121.

A may be 30wt%,35wt%,40wt% or any value within the above range, B may be 30wt%,35wt%,40wt% or any value within the above range, and C may be 20wt%,30wt%,35wt%,40wt% or any value within the above range.

The mass content a of the thermoplastic polymer is 30wt% to 40wt% based on the total mass of the first coating layer 121, which is advantageous for forming a uniform and dense insulating layer on the exposed end surface of the current collector 10 after cutting.

The mass content B of the conductive agent is 30wt% to 40wt% based on the total mass of the first coating layer 121, the first coating layer 121 has a suitable conductive property, and the electrode sheet 1 has a suitable sheet resistance, so that the electrode sheet 1 has a suitable conductivity.

The mass content C of the binder is 20wt% to 40wt% based on the total mass of the first coating layer 121, so that there is a proper adhesion between the first coating layer 121 and the current collector 10, and the risk of the first coating layer 121 falling off from the current collector 10 can be reduced.

In some embodiments, the ratio of the surface resistance R1 of the tab 102 to the surface resistance R2 of the current collector 10 provided with the first coating 121 is r1:r2 is 1 to 1.3, for example, 1,1.2,1.3 or any value in the above range.

The sheet resistance may be a resistance per unit area.

The surface resistance R1 of the tab 102 may be referred to as the surface resistance of the current collector 10 itself. In the case where the current collector 10 is aluminum foil, the sheet resistance R1 of the tab 102 refers to the sheet resistance of the aluminum foil.

The sheet resistance R2 of the current collector 10 provided with the first coating layer 121 may be the sheet resistance of the current collector 10 provided with the first coating layer 121 but not provided with the active material layer 11.

In the above embodiment, after the first coating layer 121 is provided, the electrode sheet 1 has a suitable resistance, so that the electrode sheet 1 has a suitable conductivity, and the influence on the battery cell due to the excessive resistance of the electrode sheet 1 can be reduced.

In some embodiments, the adhesion force F between the first coating 121 and the current collector 10 is 20N/m to 100N/m, e.g., F is 20N/m,60N/m,80N/m,100N/m, or any value within the above range.

In the above embodiment, having a suitable adhesive force between the first coating 121 and the current collector 10 may reduce the risk of the first coating 121 falling off from the current collector 10.

Optionally, F is 55N/m to 92N/m, for example F is 55N/m,60N/m,80N/m,92N/m or any value within the above range. The adhesion force F is related to the thickness of the first coating layer 121, and by setting the adhesion force within the above-described range, the first coating layer 121 has a proper thickness while the remaining current collector 10 of the first coating layer 121 has a proper adhesion force therebetween.

In some embodiments, the total thickness d1 of the first coating 121 is 2 μm to 14 μm, e.g., d1 is 2 μm,4 μm,6 μm,8 μm,10 μm,12 μm,14 μm, or any value within the above range. Optionally, d1 is 4 μm to 8 μm.

In the case where the first coating layers 121 are provided on both side surfaces of the main body portion 101 in the thickness direction of the pole piece 1, as shown in fig. 5, the total thickness d1 of the first coating layers 121 may be the sum of the thicknesses of the two first coating layers 121, that is, d1=d11+d12; in the case where the first coating layer 121 is provided on the surface of one side of the main body portion 101, the total thickness d1 of the first coating layer 121 is the thickness of the first coating layer 121.

The thickness of the first coating layer 121 is an average value in the thickness direction, for example, an average value of a maximum value and a minimum value in the thickness direction.

In the case that the total thickness d1 of the first coating layer 121 is not less than 2 μm, more thermoplastic polymer is contained in the first coating layer 121 during the process of cutting the current collector 10 provided with the first coating layer 121, so that more thermoplastic polymer can flow to burrs and exposed end surfaces of the current collector 10 after being heated, thereby being beneficial to uniformly and compactly coating the exposed end surfaces and burrs; in the case where the total thickness d1 of the first coating layer 121 does not exceed 14 μm, it is advantageous to reduce the space occupied by the first coating layer 121 and to increase the energy density of the battery cell.

In some embodiments, the pole piece 1 further comprises a first insulating layer 131, the first insulating layer 131 being provided at the end face 1011a of the body portion at the first end.

The end face 1011a of the body portion 101 at the first end is one face parallel to the thickness direction of the current collector 10. For example, as shown in fig. 3, the end face 1011a is a surface parallel to the x-direction and the z-direction.

The end face 1011a of the main body portion 101 at the first end may be formed through: referring to fig. 1, in the process of cutting the current collector 10, the end face 1011a is the cut end face of the first coating region 1011, which is cut along the cut line 124. After cutting, the current collector 10 at the end face 1011a is exposed and may be accompanied by burrs. By providing the first insulating layer 131 at the end face 1011a, the first insulating layer 131 can cover the end face 1011a and the burr, reducing the risk of the end face 1011a and the burr overlapping with the electrode of opposite polarity.

In the above embodiment, the first insulating layer 131 may cover the end face 1011a of the body portion 101 at the first end and burrs, so that the risk of short circuit generated by overlapping the end face 1011a with the electrode of opposite polarity may be reduced.

In some embodiments, the thickness d2 of the first insulating layer 131 is 10nm to 200nm. In this way, the first insulating layer 131 can better cover burrs and exposed surfaces with a smaller thickness.

The thickness d2 of the first insulating layer 131 may be 10nm,20nm,30nm,60nm,80nm,100nm,150nm,200nm or any value within the above range.

The thickness d2 of the first insulating layer 131 may be an average thickness. For example, as an average of the maximum thickness and the minimum thickness.

Optionally, the thickness d2 of the first insulating layer 131 is 60nm to 200nm. Thus, the coating effect on the burrs and the first end face is further improved.

In some embodiments, the material of the first insulating layer 131 is the same as the thermoplastic polymer in the first coating 121. Thus, the preparation steps of the pole piece 1 are simplified, and the production rhythm is quickened.

In some embodiments, the thermoplastic polymer of the first insulating layer 131 is a film layer. The first insulating layer 131 can also be said to comprise a thermoplastic polymer in the form of a film.

The particulate thermoplastic polymer may have a variety of shapes, such as spheres, rods, flakes. The particulate thermoplastic polymer herein means that the thermoplastic polymer does not become fluid and the thermoplastic polymer is solid.

Before the first coating layer 121 is cut, the thermoplastic polymer in the first coating layer 121 is in the form of particles. During the cutting of the first coating 121, a portion of the thermoplastic polymer in the first coating 121 changes from a solid state to a fluid state (e.g., a portion of the thermoplastic polymer near the cut line 124 changes to a fluid state), and another portion of the thermoplastic polymer remains as solid particles. The particles herein refer to particles of the thermoplastic polymer protruding from the current collector.

The first insulating layer 131 is formed after the thermoplastic polymer in the first coating 121 is melted and resolidified. After the thermoplastic polymer in the first coating layer 121 becomes fluid, it flows to the end face 1011a, and is cured at the end face 1011a to form the first insulating layer 131. In this way, it is advantageous to simplify the preparation steps of the pole piece 1, and the first insulating layer 131 can be formed while cutting.

In some embodiments, the resistance R3 of the first insulating layer 131 satisfies: r3 is more than or equal to 1Ω. For example, R3 is a value of 1Ω,10Ω, 100deg.OMEGA, or more.

In case that the resistance of the first insulating layer 131 is greater than 1Ω, even in some extreme cases, the end face 1011a is overlapped with the electrode having the opposite polarity, since the first insulating layer 131 has a certain resistance, the battery cell is not internally shorted, so that the risk of short circuit, even explosion, etc. due to the internal short circuit can be reduced.

Alternatively, R3 satisfies: r3 is more than or equal to 800 omega. The value of R3 is related to the thickness of the first insulating layer 131, and the greater the thickness of the first insulating layer 131, the greater R3 is within a certain range.

The resistance of the first insulating layer 131 satisfies the above condition, and thus, the risk of the battery cell being shorted due to the overlap of the end face 1011a with the electrode having the opposite polarity can be reduced.

In some embodiments, the thermoplastic polymer has a melting point T of 100℃to 200 ℃. For example, the thermoplastic polymer has a melting point T of 100 ℃, 150 ℃, 200 ℃ or any value within the above range.

The melting point of the thermoplastic polymer is the temperature at which the thermoplastic polymer transitions from a solid or semi-solid state to a liquid state.

The melting point of the thermoplastic polymer is not lower than 100 ℃, so that the risk of melting or flowing of the thermoplastic polymer caused by heating the pole piece 1 during other processing can be reduced. The melting point of the thermoplastic polymer does not exceed 200 ℃, which reduces the risk that the thermoplastic polymer cannot be converted into a flow state during the cutting process, thereby reducing the risk that the first insulating layer 131 cannot be formed at the exposed end face of the current collector 10 after cutting. In addition, the melting point of the thermoplastic polymer does not exceed 200 ℃, and the thermoplastic polymer can become fluid-dynamic under less heat, thereby being beneficial to reducing the energy consumed by cutting.

In the above embodiment, the thermoplastic polymer has a suitable melting point, and is changed from a solid state to a fluid state by heat generated during cutting of the current collector 10 provided with the first coating layer 121, and the fluid thermoplastic polymer may flow to the end surface of the cut bare current collector 10 and burrs generated during cutting, thereby facilitating the preparation of the first insulating layer 131.

Optionally, the thermoplastic polymer comprises: at least one of polystyrene, polyolefin, polyimide, polyester, polyphenylene sulfide, polyamide, copolymer of butyl acrylate and ethyl methacrylate, and their respective modified polymers. Alternatively, the polyamide comprises a polyaramid.

For example, the thermoplastic polymer includes at least one of a modified polymer of polystyrene, a modified polymer of polyolefin, a modified polymer of polyimide, a modified polymer of polyester, a modified polymer of polyphenylene sulfide, a modified polymer of polyamide, and a modified polymer of a copolymer of butyl acrylate and ethyl methacrylate.

By using the thermoplastic polymer described above, a uniform and dense coating is advantageously formed on the end surfaces and burrs of the cut bare current collector 10.

In some embodiments, the binder comprises: at least one of polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-polyacrylonitrile copolymer, polyether acrylate, polyacrylic acid, polyacrylonitrile, gelatin, chitosan and sodium alginate.

The above-described adhesive has good adhesion properties, and facilitates bonding the thermoplastic polymer to the surface of current collector 10.

In some embodiments, the conductive agent comprises conductive carbon; optionally, the conductive carbon comprises at least one of carbon black, ketjen black, acetylene black, superconducting carbon, carbon nanofibers, carbon nanotubes, graphene.

The superconducting carbon may also be called SP, the carbon nanofibers may also be called VGCF, and the carbon nanotubes may also be called CNT.

The conductive carbon has good conductive properties and does not react with the thermoplastic polymer, and the conductive carbon is used as a conductive agent, which is advantageous in improving the conductive properties of the first coating 121.

In some embodiments, pole piece 1 comprises a positive pole piece. Optionally, the current collector comprises aluminum foil. Thus, the pole piece 1 is a positive pole piece, which is beneficial to reducing the risk of overlapping the positive pole piece and the negative pole piece and improving the reliability of the battery cell. In addition, the risk of overlap joint generation of lithium dendrites precipitated by the positive electrode plate and the negative electrode plate is reduced.

In some embodiments, the positive electrode sheet comprises a positive electrode active material comprising LiNi _0.8 Co _0.1 Mn _0.1 O ₂ . Thus, the battery monomer prepared from the pole piece can have higher capacity.

The battery is charged and discharged with the release and consumption of Li, and the molar contents of Li are different when the battery is discharged to different states. In the application, the molar content of Li is the initial state of the material, namely the state before charging, and the molar content of Li can be changed after charge and discharge cycles when the positive electrode material is applied to a battery system.

In the application, in the list of the positive electrode materials, the molar content of O is only a theoretical state value, the molar content of oxygen can be changed due to the oxygen release of the crystal lattice, and the actual molar content of O can be floated.

It should be noted that the positive electrode active material may also be lithium iron phosphate, or other ternary materials, and embodiments of the present application include, but are not limited to, this.

In some embodiments, current collector 10 comprises a metal foil or a composite current collector. In this way, it is convenient to arrange the material of the current collector 10 according to actual needs.

Optionally, the metal foil comprises aluminum foil or copper foil.

Optionally, the composite current collector comprises: a polymer material base layer and a metal layer on at least one surface of the polymer material base layer.

Optionally, the current collector 10 comprises aluminum foil. Thus, the pole piece 1 is a positive pole piece, which is beneficial to reducing the risk of overlapping the positive pole piece and the negative pole piece and improving the reliability of the battery cell. In addition, the risk of overlap joint generation of lithium dendrites precipitated by the positive electrode plate and the negative electrode plate is reduced.

The technical solution of the pole piece is described above in connection with fig. 1 to 8, and the preparation method of the pole piece is described below in connection with fig. 9, wherein the portions corresponding to the pole piece can be referred to above, and will not be described again here.

[ preparation method of Pole piece ]

Fig. 9 is a schematic diagram of a method of preparing a pole piece according to an embodiment of the present application. The method 200 may be used to prepare the pole piece 1 in the above embodiments. The method 200 includes the following steps.

At step 210, current collector 10 is provided.

The shape and size of the current collector 10 may be set according to actual needs, for example, the shape of the current collector 10 is rectangular. Wherein one current collector 10 is used for preparing one pole piece 1; alternatively, one current collector 10 is used to prepare a plurality of pole pieces 1, which may be specifically set according to the size and actual situation of the current collector 10.

At step 220, a first slurry is applied to the first application region 1011 of the current collector 10 to form a first coating 121, the first slurry comprising a thermoplastic polymer emulsion, a conductive agent, and a binder.

The thermoplastic polymer emulsion may be a solution of the thermoplastic polymer mixed with water. The addition of the thermoplastic polymer emulsion is advantageous in accelerating the uniformity of the first slurry compared to the direct addition of the thermoplastic polymer.

The thermoplastic polymer in the thermoplastic polymer emulsion is conveniently bonded to the surface of the current collector 10 by the addition of a binder; the first coating layer 121 may have a certain conductivity by the addition of a conductive agent.

Alternatively, in step 220, the first paste may be applied only to the first coating region 1011, or the first paste may be applied to both the first coating region 1011 and the second coating region 1012.

In step 230, a second slurry is applied to the first and second application regions 1011 and 1012 of the current collector 10 to form the active material layer 11, the second slurry including the active material.

The second slurry may also include other substances, such as binders and conductive agents. The active material is easily adhered to the surface of the current collector 10 by the addition of a binder; the active material layer 11 can be made conductive to a certain extent by the addition of the conductive agent.

The sizes of the first and second coating regions 1011 and 1012 may be specifically set according to actual conditions. For example, the first coating zone 1011 has a dimension in the first direction of 3mm.

At step 240, the current collector 10 provided with the first coating 121 and the active material layer 11 is cut along the cut line 124, and at least a portion of the cut line 124 is disposed in the first coating region 1011.

At least a portion of the cut line 124 is disposed in the first coating zone 1011 such that during the cutting process, the cutting tool passes through the first coating zone 1011 and the thermoplastic polymer of the first coating zone 1011 changes from a solid state to a fluid state under the influence of the heat generated by the cutting, thereby flowing to at least a portion of the end face generated by the cutting and solidifying at the end face. In this way, the formation of the first insulating layer 131 is facilitated.

In the embodiment of the present application, the active material layer 11 is disposed at the first coating region 1011 and the second coating region 1012 of the current collector 10, which is advantageous in improving the energy density of the battery cell compared to coating the active material layer 11 only at the first coating region 1011; furthermore, by the provision of the first coating layer 121, the risk of the active material layer 11 falling off during cutting can be reduced. The first coating 121 includes a thermoplastic polymer emulsion, so that after the current collector 10 is cut, the exposed end surface of the current collector 10 after cutting is formed with the first insulating layer 131, which can reduce the risk of short circuit caused by overlapping the end surface with the electrode having opposite polarity; the first coating 121 comprises a conductive agent, and the first coating 121 and the pole piece 1 have certain conductivity; the first coating 121 includes a binder therein to facilitate bonding of the conductive agent and the thermoplastic polymer to the surface of the current collector 10. Therefore, the battery cell prepared by the method has higher energy density, and the pole piece 1 has better performance.

In some embodiments, the method 200 further comprises: the first paste is applied at the second application region 1012 of the current collector 10 to form the first coating 121.

Specifically, a first paste may be applied in the first and second application regions 1011 and 1012 of the current collector 10 to form the first coating 121 in step 220.

In the above embodiment, the first paste is applied to the first coating region 1011 and the second coating region 1012 of the current collector 10, so that only the region of the tab 102 needs to be reserved on the current collector 10, and the first paste can be applied to other regions, which is beneficial to reducing the complexity of the application. In addition, coating the first paste in the first coating region 1011 and the second coating region 1012 is advantageous in that more pole pieces 1 are cut with fewer cutting processes than coating the first paste only in the first coating region 1011. Thus, the above embodiment is advantageous in simplifying the manufacturing process of the pole piece 1 and accelerating the production rhythm.

In some embodiments, the thermoplastic polymer emulsion has a mass content A2 of 30wt% to 40wt%, the conductive agent has a mass content B of 30wt% to 40wt%, and the binder has a mass content C of 20wt% to 40wt%, based on the total mass of the first slurry.

A2 may be 30wt%,35wt%,40wt% or any value within the above range, B may be 30wt%,35wt%,40wt% or any value within the above range, and C may be 20wt%,30wt%,35wt%,40wt% or any value within the above range.

In the technical scheme, the mass content A2 of the thermoplastic polymer emulsion is 30-40 wt%, so that a uniform and compact insulating layer is formed on the exposed end face of the cut current collector 10; the mass content B of the conductive agent is 30-40 wt%, so that the pole piece 1 has proper surface resistance and the pole piece 1 has proper conductivity; the mass content C of the binder is 20-40 wt%, so that the first coating 121 and the current collector 10 have proper binding force, and the risk of the first coating 121 falling off from the current collector 10 can be reduced.

In some embodiments, the total thickness d1 of the first coating 121 is 2 μm to 14 μm. For example, d1 is 2 μm,4 μm,8 μm,10 μm,14 μm or any value within the above range.

The thickness of the first coating layer 121 refers to the thickness of the dried first coating layer 121.

In some embodiments, the viscosity P of the first slurry is 50 mPas to 500 mPas. In this way, the application of the first slurry is facilitated.

The viscosity P of the first paste may be 50 mPa-s, 100 mPa-s, 250 mPa-s, 500 mPa-s or any value within the above range.

The viscosity P of the first slurry may be specifically limited according to practical needs, and embodiments of the present application include, but are not limited to, this.

In some embodiments, the thermoplastic polymer has a melting point T of 100℃to 200 ℃.

In some embodiments, applying the first slurry at the first application region 1011 of the current collector 10 to form the first coating 121 includes: the first paste is coated on the first coating region 1011 of the current collector 10 by gravure coating to form the first coating layer 121. The first coating 121 having a smaller thickness is conveniently prepared by gravure coating.

As an example, gravure coating may be performed using a gravure coater. For example, the gravure coater includes a gravure roll, a pressure roll, and a doctor blade, and the coating of the first coating layer 121 is achieved by the cooperation of the gravure roll, the pressure roll, and the doctor blade.

In some embodiments, cutting the current collector 10 provided with the first coating layer 121 and the active material layer 11 along the cut line includes: the laser processing tool is controlled, and the current collector 10 provided with the first coating layer 121 and the active material layer 11 is cut along the cut line.

In the above technical solution, the current collector 10 is cut by laser, so that more heat can be generated during the cutting process, which is beneficial for the thermoplastic polymer in the first coating 121 to become flowing state and flow to the end surface, thereby facilitating the formation of the first insulating layer 131.

In the embodiment of the application, the use parameters of the laser can be adjusted according to the melting point of the thermoplastic polymer and the like. For example, in the case where the melting point of the thermoplastic polymer is high, the power or frequency may be increased, or the feed rate may be decreased. For another example, current collector 10 may be cut using cutting parameters that are appropriate for all conditions (e.g., thermoplastic polymers that are appropriate for multiple melting points).

[ Positive electrode sheet ]

The pole piece 1 in the embodiment of the application can be a positive pole piece. The positive pole piece comprises a positive current collector and a positive film layer arranged on the positive current collector.

The positive current collector can be a metal foil or a composite current collector. For example, the positive electrode current collector may be aluminum foil.

The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

The positive electrode film layer includes a positive electrode active material. The positive electrode active material may be a positive electrode active material for a battery known in the art. For example, the positive electrode active material is lithium iron phosphate, ternary material, lithium-rich manganese-based material, or the like.

The positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluoroacrylate resin.

The positive electrode film layer may further optionally include a conductive agent. The conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[ negative electrode sheet ]

The pole piece 1 in the embodiment of the application can be a negative pole piece. The negative pole piece comprises a negative pole current collector and a negative pole film layer arranged on the negative pole current collector.

The negative current collector may be a metal foil or a composite current collector. The negative electrode current collector may be copper foil. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

The negative electrode film layer includes a negative electrode active material therein. The negative electrode active material may employ a negative electrode active material for a battery known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like. The silicon-based material may include at least one of elemental silicon, a silicon oxygen compound, a silicon carbon compound, a silicon nitrogen compound, and a silicon alloy. The tin-based material may include at least one of elemental tin, a tin oxide, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.

The negative electrode film layer may further optionally include a conductive agent. The conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[ electrolyte ]

The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The embodiment of the application has no specific limitation on the type of electrolyte, and can be selected according to requirements. For example, the electrolyte may be liquid, gel, or all solid.

In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.

The electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis-fluorosulfonimide, lithium bis-trifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorooxalato phosphate, and lithium tetrafluorooxalato phosphate.

The solvent may include at least one of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1, 4-butyrolactone, sulfolane, dimethylsulfone, methylsulfone, and diethylsulfone.

The electrolyte may also optionally include negative electrode film-forming additives, positive electrode film-forming additives, and may also include performance additives that can improve certain properties of the battery, such as performance additives that improve the overcharge performance of the battery, improve the high temperature or low temperature performance of the battery, and the like.

[ isolation Membrane ]

The isolating film is used for isolating the positive pole piece and the negative pole piece. The embodiment of the application has no special limitation on the type of the isolating membrane, and any known porous isolating membrane with good chemical stability and mechanical stability can be selected.

The material of the isolating film 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 multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.

The positive electrode sheet, the negative electrode sheet and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.

[ Battery cell ]

The embodiment of the application provides a battery cell, which comprises the pole piece 1 in the embodiment.

The shape of the battery cell is not particularly limited in the embodiment of the present application, and may be cylindrical, square or any other shape. The battery cell can be a lithium ion battery, a lithium sulfur battery, a sodium ion battery, a magnesium ion battery and the like.

Fig. 10 is a schematic view of a battery cell according to an embodiment of the application. For example, as shown in fig. 10, the battery cell 3 is a square battery cell. The battery cell 3 includes a case 31, an end cap assembly 32, and an electrode assembly 33 disposed in the case 31.

The electrode assembly 33 may be made of a positive electrode tab, a negative electrode tab, and a separator through a winding process or a lamination process. In some embodiments, the positive electrode sheet is sheet 1 in embodiments of the present application.

The end cap assembly 32 includes electrode terminals 322, for example, as shown in fig. 10, the end cap assembly 32 includes two electrode terminals 322, one of which is a positive electrode terminal and one of which is a negative electrode terminal.

The battery cell 3 further includes a current collecting member 34, and the current collecting member 34 is used to connect the tab 102 and the electrode terminal 322 of the electrode assembly 33. For example, in the case where the electrode sheet 1 of the embodiment of the present application is a positive electrode sheet, one current collecting member 34 is used to connect a positive electrode tab and a positive electrode terminal, and the other current collecting member 34 is used to connect a negative electrode tab and a negative electrode terminal.

In some embodiments, the battery cells may be assembled into a battery module, and the number of battery cells included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.

[ Battery ]

The embodiment of the application provides a battery, which comprises the battery cells in the embodiment. Fig. 11 is a schematic view of a battery according to an embodiment of the present application. As shown in fig. 11, the battery 5 may include a plurality of battery cells (not shown in the drawing).

The battery unit 3 may be directly assembled into the battery 5, or may be assembled into a battery module, and then the battery 5 is assembled from a plurality of battery modules.

[ electric device ]

The embodiment of the application provides an electric device, which comprises the battery described in the embodiment.

Fig. 12 is a schematic diagram of an electric device according to an embodiment of the application. As shown in fig. 12, the present application provides an electric device 6 including the battery in the above embodiment.

Optionally, the power utilization device may also be an energy storage device, a lighting device, a spacecraft, and the like, and embodiments of the present application include, but are not limited to, this.

Hereinafter, embodiments of the present application are described. The following examples are illustrative only and are not to be construed as limiting the application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Examples (example)

Example 1

The pole piece in example 1 has the structure shown in fig. 5 and 6. In embodiment 1, the first coating 121 includes a first paste including a thermoplastic polymer emulsion, a conductive agent, and a binder. The mass content A of the thermoplastic polymer was 40wt%, the mass content B of the conductive agent was 30wt%, and the mass content C of the binder was 30wt%, based on the total mass of the first slurry. The total thickness d1 of the first coating 121 was 4 μm, the thermoplastic polymer was polyethylene wax, the melting point T was 130 ℃, the conductive agent was superconducting carbon SP, and the binder was polyacrylonitrile.

Examples 2 to 5

Examples 2-5 differ from example 1 in that: in the first slurry, the mass content a of the thermoplastic polymer, the mass content B of the conductive agent, and the mass content C of the binder are different. Wherein, specific parameters can be seen in Table 1.

Examples 6 to 9

Examples 6-9 differ from example 1 in that: the total thickness d1 of the first coating 121 is different.

Examples 10 to 12

Examples 10-12 differ from example 1 in that: the first coating layer 121 is a coating layer formed by single-sided coating, that is, the first coating layer 121 is coated on only one side surface of the current collector 10. Furthermore, in embodiments 10-12, the first coating 121 has a different thickness.

Examples 13 to 14

Examples 13-14 differ from example 1 in that: thermoplastic polymers are different.

Examples 15 to 17

Examples 15-17 differ from example 1 in that: in the first slurry, the mass content a of the thermoplastic polymer, the mass content B of the conductive agent, and the mass content C of the binder are different. Wherein, specific parameters can be seen in Table 1.

Example 18

Example 18 differs from example 1 in that: the total thickness d1 of the first coating 121 is different.

Example 19

Example 19 differs from example 1 in that: thermoplastic polymers differ in that they have a relatively high melting point.

Comparative example 1

Comparative example 1 differs from example 1 in that: the first coating layer is positioned differently and the substance included in the first coating layer is different.

Specifically, in comparative example 1, the first coating layer was an insulating layer provided on the surfaces of the first coating region and the portion of the tab (the portion near the first coating region, which portion has a width of 10 mm); the slurry of the insulating layer comprises boehmite and a binder, wherein the mass ratio of the boehmite to the binder is 70wt%:30wt%; the insulating layer was provided on both surfaces of the current collector, and the total thickness of the insulating layer was 50 μm.

In Table 1, T is the melting point of the thermoplastic polymer, d1 is the total thickness of the first coating, A is the mass content of thermoplastic polymer added during the preparation; b is the mass content of the conductive agent added in the preparation process; c is the mass content of the binder added in the preparation process, F is the binding force between the first coating and the current collector, and R1 and R2 are the surface resistance ratio of the current collector before and after the first coating is arranged; d2 is the thickness of the first insulating layer, R3 is the resistance of the first insulating layer, and P is the viscosity of the slurry of the first coating layer. In Table 2, E1/E0 is the ratio of the volumetric energy density of the battery cells of the examples to the volumetric energy density of the comparative examples. Short-circuiting at a partial position means that a short-circuit occurs at the end face where the thermoplastic polymer is not provided.

Table 1 parameters of examples and comparative examples

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Table 2 experimental results of comparative examples and examples

[ preparation of Battery cell ]

(1) Sizing agent for preparing first coating

Mixing thermoplastic polymer emulsion, conductive agent and adhesive according to a certain proportion, adding solvent and uniformly stirring. Wherein the solvent is water, the conductive agent is SP, and the binder is polyacrylonitrile.

(2) Coating and drying

The slurry of the first coating is coated on the aluminum foil in a gravure coating mode, the width of the prepared empty foil is 30mm (so as to prepare the tab), and the coating area of the insulating layer is not reserved. The thickness of the first coating after drying by oven drying at 100℃is shown in Table 1.

And continuously coating a second slurry on the first coating to prepare an active material layer, and rolling to prepare the positive plate.

The active substances in the second slurry are ternary materials (NCM 811), a conductive agent acetylene black and a binder PVDF.

(3) Laser die cutting

And (3) die cutting the product, wherein the laser parameter is set to 20W,100kHz and the tape feeding speed is 30m/min.

(4) Manufacturing battery monomer

And combining the positive electrode plate with other components required by the battery: the negative pole piece, the diaphragm and the electrolyte are assembled together to form the lithium ion battery cell. Wherein the active material of the negative electrode plate is graphite, the diaphragm is a polyethylene porous polymer film, and the solute of the electrolyte is LiPF ₆ 。

The above is a method for producing a battery cell according to an embodiment of the present application, and a method for producing a comparative example is briefly described below.

Aluminum foil is adopted as a current collector, the width of the empty foil for preparing the tab is 30mm, and the width of the empty foil is 10mm additionally reserved for coating an insulating layer, wherein slurry of the insulating layer comprises boehmite and a binder; an active material layer was then prepared at the remaining location of the aluminum foil. The rest of the preparation method is the same as that of the embodiment, and is not repeated here.

In the examples and comparative examples of the present application, the battery cells have the same volume; in an embodiment of the present application, the battery cells have the same capacity.

[ confirmation of first insulating layer ]

The end face was observed using a Scanning Electron Microscope (SEM) to see if there was a first insulating layer at the end face. In addition, the thickness of the first insulating layer can also be observed by a photograph taken by a scanning electron microscope.

[ confirmation of first coating ]

And observing the surface of the pole piece by adopting a scanning electron microscope, and checking whether the surface has the first coating. And cutting the pole piece, shooting the section of the pole piece by adopting a scanning electron microscope, and observing the thickness of the first coating according to the shot picture.

In addition, the thickness of the first coating layer may be determined according to the thickness of the coating layer during the preparation process.

[ test of surface resistance ]

The sheet resistance of the samples was measured using a pole piece resistance meter, as an example, the samples were cut into rectangular dimensions of approximately 5cm by 10 cm.

The surface resistance of the current collector can be obtained by testing the surface resistance of the empty aluminum foil.

The sheet resistance of the current collector provided with the first coating layer may be tested after the aluminum foil is coated with the first coating layer and dried.

[ test of volumetric energy Density ]

In the environment of room temperature (25 ℃ +/-2 ℃), discharging to 3V in a constant-current discharging mode (1/3C multiplying power) to a lower limit voltage, standing for 30min, then charging to 4.25V in an upper limit cut-off voltage in a constant-current constant-voltage charging mode (constant-current 1/3C, constant-voltage charging to 1/20C), standing for 30min, measuring discharge energy E (in terms of Wh), repeating for 3 times, taking the average value of the discharge energy E for 3 times, dividing the average value by the volume V of a battery cell, and then obtaining the volume energy density (in terms of Wh/L) =voltage/V.

[ Lap joint full charge anode test ]

And (5) using the end face after laser die cutting to overlap the full charge anode, and observing whether a short circuit exists.

[ test of whether or not the active material layer is peeled off after cutting ]

And detecting by adopting a CCD online visual detector, specifically detecting whether the active material layer falls off after the tab is prepared.

[ test of resistance of first insulating layer ]

The resistance of the first insulating layer may be measured using an ohmmeter.

For example, one end of the ohmmeter is connected with the tab of the positive electrode plate in the embodiment, the other end is connected with the tab of the negative electrode plate, and the negative electrode plate is lapped with the end face of the positive electrode plate.

[ test of adhesion ]

Selecting a platy material with a flat surface as a first substrate, adhering one surface of the double-sided adhesive tape to the surface of the first substrate, and adhering the other surface of the double-sided adhesive tape to a first insulating layer on one side of the pole piece. A plate with an adhesive coated area is selected as a second substrate that is adhered to the first insulating layer on the other side of the pole piece. At this time, the pole piece is located between the first substrate and the second substrate. And respectively fixing the same sides of the first substrate and the second substrate at the lower end and the upper end of a universal tensile testing machine for tensile testing, recording a tension value and a displacement value after a force-relative displacement curve displayed on the universal tensile testing machine runs steadily, and selecting a section with a relatively steady curve to calculate the binding force, wherein the binding force=tension/displacement.

[ confirmation of melting Point of thermoplastic Polymer ]

The melting point of the thermoplastic polymer may be determined by a Differential Scanning Calorimeter (DSC) apparatus. Specifically, as an example, 8mg of a sample was put into a DSC apparatus, and heated under an atmosphere of N2 at a flow rate of 50ml/min at a heating rate of 10 ℃/min at a cutoff temperature of 400 ℃, thereby testing the melting point of the thermoplastic polymer.

For another example, the melting point of the thermoplastic polymer may be determined after a particular class of thermoplastic polymer, depending on the particular thermoplastic polymer. As an example, for crystalline thermoplastic polymers, the melting point refers to the melting point of the crystalline thermoplastic polymer; for amorphous thermoplastic polymers. Melting point refers to the glass transition temperature of the amorphous thermoplastic polymer.

[ mass ratio of thermoplastic Polymer, conductive agent and Binder ]

The above mass ratio can be obtained according to the mass of the thermoplastic polymer emulsion, the mass of the conductive agent and the mass of the binder added during the preparation process.

In examples 1-19, the volumetric energy density of the cell was E1; in comparative example 1, the volumetric energy density of the battery cell was E0. The battery cells in examples and comparative examples have the same volume, and the discharge energy (capacity) of the battery cells in examples 1 to 19 is substantially the same, and thus, examples 1 to 19 have the same volumetric energy density; an insulating layer was additionally provided in comparative example 1 (the region where the insulating layer was provided was not coated with an active material layer), and thus discharge energy (capacity) of comparative example 1 was low.

As shown in the combination examples 1 to 19, the volumetric energy density of the battery cell was increased, and the active material layer was not peeled off from the current collector during the cutting.

In combination with examples 2-5, the mass content A of the thermoplastic polymer is set to be 30-40 wt%, the mass content B of the conductive agent is set to be 30-40 wt%, and the first insulating layer has proper thickness and proper resistance at the end face under the condition that the mass content C of the binder is 20-40 wt%, so that short circuit phenomenon can not occur when the end face of the positive pole piece is overlapped with the full charge anode; the binding force between the first coating and the current collector is proper, and the first coating cannot fall off from the current collector; the value R1 and R2 is proper, and the resistance of the current collector is slightly increased. As shown in the combination example 15, when the mass content of the conductive agent is small, R1: R2 is large, and the resistance of the battery cell increases, which is disadvantageous for improvement of the rate performance of the battery cell. As shown in the bonding example 16, at a smaller mass content of the thermoplastic polymer, the thermoplastic polymer in the first coating layer was smaller, and the first insulating layer was not present at part of the end face. As shown in the combination example 17, when the mass content of the binder is small, the binding force F is small, and the first coating layer drops off after soaking in the electrolyte, so that it is difficult to prepare the battery cell.

In combination with examples 6-9, the thickness of the first insulating layer is related to the thickness of the first coating layer, and the pole piece has better performance under the condition that the thickness of the first insulating layer is 2-14 μm. In the case where the thickness of the first coating layer is less than 2 μm, the thermoplastic polymer in the first coating layer is less and the first insulating layer is not present at part of the end face as shown in the bonding example 18.

As shown in the combination of examples 1 to 9 and 10 to 12, the first coating layer may be provided on one side surface of the main body portion of the current collector, or may be provided on both side surfaces of the main body portion.

In the case where the melting point of the thermoplastic polymer is high, as shown in examples 13 to 14 and example 19, the thermoplastic polymer is more resistant to melting during cutting (requires a larger cutting power), so that the first insulating layer is provided at a part of the end face and the insulating layer is not provided at a part of the end face. When the end face is overlapped with the full-charge anode, short circuit occurs at part of the positions. Thermoplastic polymers with melting points of 100-200 ℃ are selected, so that the end faces can be uniformly coated, and the risk of short circuit is reduced.

The present application is not limited to the above embodiment. The above embodiments are merely examples, and embodiments having substantially the same configuration and the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Further, various modifications that can be made to the embodiments and other modes of combining some of the constituent elements in the embodiments, which are conceivable to those skilled in the art, are also included in the scope of the present application within the scope not departing from the gist of the present application.

Claims

1. A pole piece, comprising: the current collector, the first coating and the active material layer are sequentially arranged along the thickness direction of the pole piece;

wherein,,

the current collector comprises a main body part and a tab, wherein the tab extends from a first end of the main body part, the first end is one end of the main body part along a first direction, the main body part comprises a first coating area and a second coating area, and the first coating area is arranged between the second coating area and the tab;

the active material layer is arranged on the surfaces of the first coating area and the second coating area;

at least a portion of the first coating is disposed on a surface of the first coating zone, the first coating including a thermoplastic polymer, a conductive agent, and a binder.

2. The pole piece of claim 1, wherein at least a portion of the first coating is disposed on surfaces on both sides of the first coating zone.

3. The pole piece of claim 1, wherein at least a portion of the first coating is disposed on a surface of one side of the first coating zone.

4. The pole piece of claim 1, wherein the first coating is disposed on a surface of the first coating zone and the second coating zone.

5. The pole piece according to claim 1, characterized in that the mass content a of the thermoplastic polymer is 30wt% to 40wt%, the mass content B of the conductive agent is 30wt% to 40wt%, and the mass content C of the binder is 20wt% to 40wt%, based on the total mass of the first coating layer.

6. The pole piece of claim 1, wherein the ratio of the surface resistance R1 of the tab to the surface resistance R2 of the current collector provided with the first coating is r1:r2 of 1 to 1.3.

7. The pole piece of claim 1, wherein the adhesion force F between the first coating and the current collector is 20N/m to 100N/m.

8. The pole piece of claim 7, wherein the adhesion force F between the first coating and the current collector is 55N/m to 92N/m.

9. The pole piece of claim 1, wherein the total thickness d1 of the first coating is 2-14 μm.

10. The pole piece of claim 9, wherein the total thickness d1 of the first coating is 4-8 μm.

11. The pole piece of claim 1, further comprising a first insulating layer disposed on an end face of the body portion at the first end.

12. The pole piece of claim 11, wherein the thickness d2 of the first insulating layer is 10nm to 200nm.

13. The pole piece of claim 12, wherein the thickness d2 of the first insulating layer is 50nm to 200nm.

14. The pole piece of claim 11, wherein the material of the first insulating layer is the same as the material of the thermoplastic polymer in the first coating layer.

15. The pole piece of claim 11, wherein the thermoplastic polymer of the first insulating layer is a film laminate.

16. The pole piece of claim 11, wherein the resistance R3 of the first insulating layer satisfies: r3 is more than or equal to 1Ω.

17. The pole piece of claim 16, wherein the resistance R3 of the first insulating layer satisfies: r3 is more than or equal to 800 omega.

18. The pole piece of claim 1, wherein the thermoplastic polymer has a melting point T of 100 ℃ to 200 ℃.

19. The pole piece of claim 1, wherein the thermoplastic polymer comprises: at least one of polystyrene, polyolefin, polyimide, polyester, polyphenylene sulfide, polyamide, copolymer of butyl acrylate and ethyl methacrylate, and their respective modified polymers.

20. The pole piece of claim 1, wherein the binder comprises: at least one of polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-polyacrylonitrile copolymer, polyether acrylate, polyacrylic acid, polyacrylonitrile, gelatin, chitosan and sodium alginate.

21. The pole piece of claim 1, wherein the conductive agent comprises conductive carbon.

22. The pole piece of claim 21, wherein the conductive carbon comprises at least one of carbon black, ketjen black, acetylene black, superconducting carbon, carbon nanofibers, carbon nanotubes, graphene.

23. The pole piece of any of claims 1-22, wherein the pole piece comprises a positive pole piece.

24. The pole piece of claim 23, wherein the current collector comprises aluminum foil.

25. The pole piece of claim 23, wherein the positive pole piece comprises a positive active material comprising LiNi _0.8 Co _0.1 Mn _0.1 O ₂ 。

26. The preparation method of the pole piece is characterized by comprising the following steps:

providing a current collector;

applying a first slurry to a first application region of the current collector to form a first coating, the first slurry comprising a thermoplastic polymer emulsion, a conductive agent, and a binder;

Coating a second slurry on the first and second coating regions of the current collector to form an active material layer, the second slurry including an active material;

and cutting the current collector provided with the first coating layer and the active material layer along a cutting line, wherein at least part of the cutting line is arranged in the first coating area.

27. The method of claim 26, wherein the method further comprises: the first slurry is coated on the second coating region of the current collector to form the first coating layer.

28. The method of claim 26, wherein the thermoplastic polymer emulsion has a mass content a of thermoplastic polymer of 30wt% to 40wt%, the conductive agent has a mass content B of 30wt% to 40wt%, and the binder has a mass content C of 20wt% to 40wt%, based on the total mass of the first slurry.

29. The method of claim 26, wherein the total thickness d1 of the first coating is 2-14 μm.

30. The method of claim 26, wherein the viscosity P of the first slurry is 50 mPa-s to 500 mPa-s.

31. The method of claim 26, wherein the thermoplastic polymer in the thermoplastic polymer emulsion has a melting point T of 100 ℃ to 200 ℃.

32. The method of claim 26, wherein the thermoplastic polymer in the thermoplastic polymer emulsion comprises: at least one of polystyrene, polyolefin, polyimide, polyester, polyphenylene sulfide, polyamide, copolymer of butyl acrylate and ethyl methacrylate, and their respective modified polymers.

33. The method of claim 26, wherein the binder comprises: at least one of polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-polyacrylonitrile copolymer, polyether acrylate, polyacrylic acid, polyacrylonitrile, gelatin, chitosan and sodium alginate.

34. The method of claim 26, wherein the conductive agent comprises conductive carbon.

35. The method of claim 34, wherein the conductive carbon comprises at least one of carbon black, ketjen black, acetylene black, superconducting carbon, carbon nanofibers, carbon nanotubes, graphene.

36. The method of claim 26, wherein applying a first slurry to the first application region of the current collector to form a first coating comprises:

and coating the first slurry on the first coating area of the current collector by means of gravure coating to form the first coating.

37. The method according to any one of claims 26 to 36, wherein the cutting the current collector provided with the first coating layer and the active material layer along the cut line includes:

and controlling a laser processing tool, and cutting the current collector provided with the first coating and the active material layer along the cutting line.

38. A battery cell comprising a pole piece according to any one of claims 1-25, and/or a pole piece prepared by a method according to any one of claims 26-37.

39. A battery comprising the cell of claim 38.

40. An electrical device comprising a battery as in claim 39.