CN116632162B

CN116632162B - Pole piece, preparation method thereof, battery monomer, battery and electricity utilization device

Info

Publication number: CN116632162B
Application number: CN202310904927.7A
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: 2023-11-17
Anticipated expiration: 2043-07-24
Also published as: CN116632162A

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 a second coating; 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; at least part of the first coating is arranged on the surface of the first coating area, the first coating comprises a microcapsule, the microcapsule comprises a core material and a shell for coating the core material, the material of the shell comprises a polymer, and the material of the core material comprises a liquid insulating substance; at least a portion of the second coating is disposed on a surface of the second coating region, the second coating including an active substance. The technical scheme of the application is beneficial to improving the liquid retention rate of the pole piece and the cycle performance of the battery monomer.

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 monomer is crucial to the performance of the battery monomer, so how to provide a pole piece to improve the liquid retention rate of the pole piece and the cycle performance of the battery monomer is a technical problem to be solved urgently.

Disclosure of Invention

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

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, there is provided a pole piece comprising: a current collector, a first coating and a second coating; 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; at least part of the first coating is arranged on the surface of the first coating area, the first coating comprises a microcapsule, the microcapsule comprises a core material and a shell for coating the core material, the material of the shell comprises a polymer, and the material of the core material comprises a liquid insulating substance; at least a portion of the second coating is disposed on a surface of the second coating region, the second coating including an active substance.

In an embodiment of the application, the first coating comprises microcapsules, the microcapsules comprise a shell and a core, the material of the shell comprises a polymer, and the material of the core comprises a liquid insulating substance. In the process of cutting the current collector to prepare the tab, the cutting tool cuts the first coating, so that the microcapsules in the first coating are broken under the action of the cutting tool. The material in the core material of the broken microcapsule flows out, and the material of the core material comprises liquid insulating material, so that adverse effects on the battery cells caused by the material flow out of the core material can be reduced. The shell of the broken microcapsule can absorb electrolyte with certain mass, so that the quantity of the electrolyte retained by the pole piece can be increased, and the cycle performance of the battery monomer can be improved; the first coating area is provided with the first coating, and the first coating area is close to the tab for the second coating area, remains the electrolyte of certain quality in the part of pole piece that is close to the tab, is favorable to further improving battery monomer's cycle performance. Therefore, the technical scheme of the embodiment of the application is beneficial to improving the liquid retention rate of the pole piece and the cycle performance of the battery monomer.

In one possible implementation, the second coating layer is disposed on the surfaces of the first coating region and the second coating region, and the first coating layer is disposed on the surface of the first coating region.

In the technical scheme, the second coating is arranged on the surfaces of the first coating area and the second coating area, and compared with the surface of the second coating area, the second coating is positioned on the surface of the second coating area, so that the energy density of the battery cell is improved. The first coating is arranged on the surface of the first coating area, compared with the first coating which is arranged on the surfaces of the first coating area and the second coating area, the use amount of the microcapsule is reduced, and the production cost is reduced.

In one possible implementation, the second coating layer is disposed on surfaces of the first coating region and the second coating region, and the first coating layer is disposed on surfaces of the first coating region and the second coating region.

In the technical scheme, the first coating is arranged on the surfaces of the first coating area and the second coating area, so that the first coating is arranged on the surface of the main body part, the preparation process of the pole piece is simplified, and the production rhythm is accelerated.

In one possible implementation, the volume particle size distribution Dv50 of the microcapsules satisfies: dv50 is less than or equal to 0.5 μm and less than or equal to 10 μm. In the case where the volume particle diameter distribution Dv50 of the microcapsules is not less than 0.5 μm, the risk of agglomeration of the microcapsules during the preparation of the first coating layer can be reduced; in the case where the volume particle diameter distribution Dv50 of the microcapsules does not exceed 10 μm, the risk of the thickness of the first coating layer being difficult to control during the coating process due to the larger particle diameter of the microcapsules can be reduced. Optionally, the microcapsules have a volume particle size distribution Dv50 that satisfies: dv50 is less than or equal to 2 mu m and less than or equal to 6 mu m.

In one possible implementation, the total thickness d1 of the first coating layer satisfies: d1 is more than or equal to 2 mu m and less than or equal to 10 mu m; alternatively, d1 satisfies: d1 is less than or equal to 2 mu m and less than or equal to 6 mu m.

In the above technical solution, under the condition that the total thickness d1 of the first coating is not less than 2 μm, in the process of cutting the current collector provided with the first coating, more microcapsules in the first coating are more, so that more microcapsules are broken, the core material flows to the burrs and the exposed end face of the current collector, and a relatively uniform insulating layer is formed to uniformly and compactly cover the exposed end face and the burrs; in the case that the total thickness d1 of the first coating layer does not exceed 10 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 adhesion force F between the first coating and the current collector satisfies: f is more than or equal to 20N/m and less than or equal to 100N/m; optionally, F satisfies: f is more than or equal to 70N/m and less than or equal to 80N/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 mass content a of the microcapsules, based on the total mass of the first coating, satisfies: a is more than or equal to 30wt% and less than or equal to 40wt%. The mass content A of the microcapsule is 30-40 wt%, so that a uniform and compact insulating layer can be formed on the exposed end face of the cut current collector.

In one possible implementation, the mass content D of the core material, based on the total mass of the microcapsules, satisfies: d is more than or equal to 60wt% and less than or equal to 80wt%. Thus, in the case of microcapsule rupture, a core material with a proper content flows out, flows to the end face and is solidified at the end face, which is beneficial to forming a relatively uniform and compact insulating layer.

In one possible implementation, the material of the housing includes: at least one of melamine resin, urea resin and melamine-urea-formaldehyde copolycondensation resin, wherein the material of the core material comprises: at least one of oleum Verniciae Fordii, catalpa oil and oleum Lini.

In the technical scheme, the shell can be destroyed when being subjected to the action of external shearing force, so that the core material can flow out conveniently; the core material includes the above-mentioned insulating substance that can flow, can flow to the terminal surface after the above-mentioned insulating substance flows out from the shell and solidify at the terminal surface.

In one possible implementation, the first coating layer further includes a conductive agent, based on the total mass of the first coating layer, the mass content B of the conductive agent satisfies: b is more than or equal to 30wt% and less than or equal to 40wt%.

According to the technical scheme, through the arrangement of the conductive agent, the current collector provided with the first coating has certain conductivity, so that the influence of the microcapsule on the conductivity of the pole piece can be reduced.

In one possible implementation, the ratio of the area resistance R1 of the current collector to the area resistance R2 of the current collector provided with the first coating layer satisfies: r1 is more than or equal to 1, and R2 is more than or equal to 1.3. Thus, the current collector provided with the first coating 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 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 microcapsule, and is used as a conductive agent, thereby being beneficial to improving the conductive performance of the first coating.

In one possible implementation, the first coating layer further includes a binder, based on the total mass of the first coating layer, the mass content C of the binder satisfying: c is more than or equal to 20wt% and less than or equal to 40wt%; optionally, C satisfies: c is more than or equal to 30wt% and less than or equal to 40wt%.

According to the technical scheme, the microcapsule can be adhered to the surface of the current collector through the arrangement of the adhesive, and the first coating and the current collector are provided with proper adhesive force through reasonably arranging the mass content of the adhesive, so that the risk that the first coating falls off from the current collector can be reduced.

In one possible implementation, the second coating layer is disposed on a surface of the second coating region, and the first coating layer is disposed on a surface of the first coating region and a portion of a surface of the tab. Therefore, the first coating is arranged on the part of the surface of the tab, so that the short circuit risk caused by overlapping of the part of the surface of the tab and the electrode with opposite polarity can be reduced.

In one possible implementation, the pole piece further comprises an insulating layer disposed at an end face of the body portion at the first end. The insulating layer can cover the end face, so that the risk of short circuit generated by overlapping the end face and the electrode with opposite polarity can be reduced, and the reliability of the battery cell can be improved.

In one possible implementation, the material of the core material further includes: a drier; optionally, the drier comprises: at least one of rare earth isooctanoate and cobalt isooctanoate. The drier can accelerate the solidification of the liquid insulating substance, and thus can promote the solidification of the substance flowing out of the broken microcapsule at the end face to form the insulating layer.

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 one possible implementation, the pole piece is a positive pole piece.

In a second aspect, a method for preparing a pole piece is provided, including: coating a first slurry on a first coating area of a current collector to form a first coating, wherein the first slurry comprises microcapsules, the microcapsules comprise a core material and a shell for coating the core material, the material of the shell comprises a polymer, and the material of the core material comprises a liquid insulating substance; coating a second slurry on a second coating region of the current collector to form a second coating layer, wherein the second slurry comprises an active substance; and cutting the current collector provided with the first coating and the second coating along a cutting line, wherein at least part of the cutting line is arranged in the first coating area.

In the technical scheme, when the pole piece prepared by the method is used for a battery monomer, the liquid retention rate of the pole piece and the cycle performance of the battery monomer are improved.

In one possible implementation, the method further includes: the second slurry is coated on the first coating region of the current collector to form the second coating layer. In this way, the first coating area and the second coating area of the current collector are both coated with the second slurry, and the second coating is arranged in the first coating area and the second coating area, so that more active substances are included in the prepared pole piece, and the energy density of the battery cell is improved.

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. The first coating area and the second coating area of the current collector are both coated with first slurry, and the first coating is arranged in the first coating area and the second coating area. Thus, more pole pieces can be obtained through fewer cutting times.

In one possible implementation, the volume particle size distribution Dv50 of the microcapsules satisfies: dv50 is less than or equal to 0.5 mu m and less than or equal to 10 mu m; optionally, the microcapsules have a volume particle size distribution Dv50 that satisfies: dv50 is less than or equal to 2 mu m and less than or equal to 6 mu m.

In one possible implementation, the mass content a of the microcapsules, based on the total mass of the first slurry, satisfies: a is more than or equal to 30wt% and less than or equal to 40wt%; optionally, the mass content D of the core material, based on the total mass of the microcapsules, satisfies: d is more than or equal to 60wt% and less than or equal to 80wt%; optionally, the material of the housing includes: at least one of melamine resin, urea resin and melamine-urea-formaldehyde copolycondensation resin, wherein the material of the core material comprises: at least one of oleum Verniciae Fordii, catalpa oil and oleum Lini.

In one possible implementation, the first paste further includes a conductive agent and a binder, and the mass content B of the conductive agent, based on the total mass of the first paste, satisfies: b is more than or equal to 30wt% and less than or equal to 40wt%, and the mass content C of the binder satisfies the following conditions: c is more than or equal to 20wt% and less than or equal to 40wt%.

In one possible implementation, the material of the core material further includes: a drier; optionally, the drier comprises: at least one of rare earth isooctanoate and cobalt isooctanoate.

In one possible implementation, applying a first slurry to a 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, the cutting the current collector provided with the first coating layer and the second coating layer along the cutting line includes: and controlling a cutter to cut the current collector provided with the first coating and the second coating along the cutting line. Thus, in the process of cutting using the cutter, the cutter can cut off the microcapsules located on the cutting line, so that the core material in the microcapsules flows out to the end face of cutting to form the insulating layer.

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 schematic illustration of a microcapsule according to an embodiment of the application;

FIG. 6 is a schematic view of a pole piece according to another embodiment of the present application;

FIG. 7 is a cross-sectional view taken along the direction A-A in FIG. 6;

FIG. 8 is a cross-sectional view taken along the B-B direction in FIG. 6;

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

FIG. 10 is a cross-sectional view taken along the direction A-A in FIG. 9;

FIG. 11 is a cross-sectional view taken along the B-B direction in FIG. 9;

FIG. 12 is a schematic view of a pole piece according to an embodiment of the present application;

FIG. 13 is a cross-sectional view taken along the direction A-A in FIG. 12;

FIG. 14 is a cross-sectional view taken along the direction B-B in FIG. 12;

FIG. 15 is a schematic illustration of a method of making a pole piece according to an embodiment of the present application;

FIG. 16 is a schematic view of a battery cell according to an embodiment of the application;

FIG. 17 is a schematic view of a battery according to an embodiment of the application;

fig. 18 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: a second coating; 12: a first coating; 13: an insulating layer; 101: a main body portion; 102: a tab; 1011: a first coating zone; 1012: a second coating zone; 1011a: an end face.

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 reliability of the battery cells. The pole piece generally comprises a current collector and active material layers and ceramic material layers coated on different areas of the current collector, and after the current collector is coated with the corresponding active material layers and ceramic material layers, the current collector coated with the active material layers and the ceramic material layers needs to be cut to cut out the tab. After the pole piece, the pole piece with opposite polarity and the isolating film are coiled or laminated to prepare the battery monomer, the cycle performance of the battery monomer is lower.

In view of this, the present application provides a pole piece comprising: a current collector, a first coating and a second coating; 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; at least a portion of the second coating is disposed on a surface of the second coating region, the second coating comprising an active substance; at least part of the first coating is arranged on the surface of the first coating area, the first coating comprises a microcapsule, the microcapsule comprises a core material and a shell for coating the core material, the material of the shell comprises a polymer, and the material of the core material comprises a liquid insulating substance. Therefore, the pole piece has higher liquid retention rate, and the battery monomer has better cycle performance.

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 connection with fig. 1 to 4, the pole piece 1 comprises a current collector 10, a first coating 12 and a second coating 11.

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 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.

At least a portion of the second coating 11 is disposed on the surface of the second coating region 1012, the second coating 11 including an active material.

The second coating layer 11 may also be referred to as an active material layer, and the second coating layer 11 may include a conductive agent and a binder in addition to the active material.

At least a portion of the second coating 11 is disposed on the surface of the second coating region 1012, which may include the following: the second coating layer 11 is disposed only on the surface of the second coating region 1012, or the second coating layer 11 is disposed on the surface of the second coating region 1012 and the surface of the first coating region 1011.

The second coating layer 11 is disposed on the surface of the second coating region 1012, which may mean that the second coating layer 11 is disposed on at least one side surface of the second coating region 1012.

Along opposite sides of the thickness direction of the pole piece 1, the body portion 101 (e.g., the second coating region 1012 of the body portion 101) has opposite surfaces. For example, as shown in fig. 3 and 4, both surfaces of the second coating region 1012 opposite in the thickness direction thereof are provided with the second coating layer 11.

At least a portion of the first coating 12 is disposed on the surface of the first coated region 1011. Wherein the first coating layer 12 may be disposed only on the surface of the first coating region 1011; may be disposed on the surfaces of the first coating region 1011 and the second coating region 1012, but not on the surface of the tab 102; may be disposed on a portion of the surfaces of the first coating region 1011 and the tab 102, but not on the surface of the second coating region 1012.

The first coating layer 12 may be disposed on one side surface of the first coating region 1011 or on both sides of the first coating region 1011. For example, as shown in fig. 3 and 4, the first coating layer 12 is provided on the surfaces of both sides of the first coating region 1011.

Fig. 5 is a schematic view of a microcapsule according to an embodiment of the application. As shown in fig. 3 to 5, the first coating layer 12 includes the microcapsule 2, the microcapsule 2 includes the core 22 and the outer shell 21 that covers the core 22, the material of the outer shell 21 includes a polymer, and the material of the core 22 includes a liquid insulating substance.

The microcapsule 2 has a core-shell structure, the shell 21 of which may be a solid shell, and the core 22 of which is a liquid insulating material.

The material of the shell 21 comprises a polymer such that the microcapsules 2 have certain insulating properties without rupture of the microcapsules 2.

In the process of cutting the current collector 10 to prepare the tab 102, the microcapsule 2 of the first coating region 1011 is broken, and the shell 21 of the broken microcapsule 2 can absorb electrolyte with a certain mass, so that the amount of the electrolyte retained by the pole piece 1 can be increased, and the cycle performance of the battery cell can be improved; the first coating region 1011 is provided with the first coating 12, the first coating region 1011 is closer to the tab 102 than the second coating region 1012, and a certain amount of electrolyte is reserved at a portion of the pole piece 1 close to the tab 102, which is beneficial to further improving the cycle performance of the battery cell.

The material of the core material 22 includes a liquid insulating substance such that the microcapsules 2 of the first coating region 1011 are ruptured during the process of cutting the current collector 10 to prepare the tab 102, and the core material 22 flows out of the outer case 21, so that the flowing insulating substance can reduce the influence on the electrode sheet, thereby reducing the adverse influence on the battery cells.

In the case where the microcapsule 2 is not broken, the insulating substance in the core 22 is a liquid substance. After the microcapsule 2 is broken, the liquid insulating material in the core material 2 is oxidized by air and dried to form a solid film after encountering air. For example, the liquid insulating substance in the core 22 can flow to the end face 1011a where the bare end is cut, and solidify at the end face 1011a to form the insulating layer 13.

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. 2 and 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 insulating layer 13 at the end face 1011a, the insulating layer 13 can encapsulate 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 embodiment of the present application, at least part of the first coating layer 12 is disposed on the surface of the first coating region 1011, so that the surface of the first coating region 1011 of the main body part 101 is provided with the first coating layer 12, and the first coating layer 12 includes the microcapsules 2. In the process of cutting the current collector 10 to prepare the tab 102, a cutting tool cuts the first coating 12, so that the microcapsules 2 in the first coating 12 are broken under the action of the cutting tool, and the shell 21 of the broken microcapsules 2 can absorb electrolyte with a certain mass, so that the electrolyte retention amount of the pole piece 1 can be increased, and the cycle performance of a battery monomer can be improved; the first coating region 1011 is provided with the first coating 12, the first coating region 1011 is closer to the tab 102 than the second coating region 1012, and a certain amount of electrolyte is reserved at a portion of the pole piece 1 close to the tab 102, which is beneficial to further improving the cycle performance of the battery cell. The microcapsules 2 of the first coating region 1011 are broken, the core material 22 flows out from the outer shell 21, and the influence of the flowing insulating material on the pole piece 1 can be reduced, so that the adverse influence on the battery cell is reduced; in addition, the substance in the core 22 of the microcapsule 2 flows out and can flow to the end face 1011a of the main body 101 at the first end, which contributes to the formation of the insulating layer 13 at the end face 1011a, so that the risk of short circuit caused by overlapping of the end face 1011a with an electrode of opposite polarity can be reduced, which contributes to the improvement of the reliability of the battery cell.

Fig. 6 is a schematic view of a pole piece according to another embodiment of the present application, fig. 7 is a cross-sectional view along A-A in fig. 6, and fig. 8 is a cross-sectional view along B-B in fig. 6. In some embodiments, as shown in connection with fig. 6-8, the second coating 11 is disposed on the surface of the first coating region 1011 and the second coating region 1012, and the first coating 12 is disposed on the surface of the first coating region 1011.

The first coating 12 is located between the current collector 10 and the second coating 11 in the thickness direction of the pole piece 1.

The second coating 11 is disposed on the surfaces of the first coating region 1011 and the second coating region 1012, and the pole piece 1 includes more active material than the second coating 11 is disposed on the surface of the second coating region 1012, which is advantageous for improving the energy density of the battery cell. The first coating layer 12 is disposed on the surface of the first coating region 1011, which is advantageous in reducing the usage amount of the microcapsules 2 compared to the first coating layer 12 disposed on the surfaces of the first coating region 1011 and the second coating region 1012, thereby being advantageous in reducing the production cost.

Fig. 9 is a schematic view of a pole piece according to an embodiment of the present application, fig. 10 is a sectional view taken along A-A in fig. 9, and fig. 11 is a sectional view taken along B-B in fig. 9. In some embodiments, as shown in connection with fig. 9 to 11, the second coating 11 is disposed on the surfaces of the first coating region 1011 and the second coating region 1012, and the first coating 12 is disposed on the surfaces of the first coating region 1011 and the second coating region 1012.

As an example, the pole piece 1 is prepared by the following method. A current collector 10 having a large area is provided, a second coating 11 and a first coating 12 are coated on the current collector 10, and then the current collector 10 provided with the second coating 11 and the first coating 12 may be cut into a plurality of electrode sheets. Applying the first coating 12 in the first coating region 1011 and the second coating region 1012 is advantageous in reducing the number of cuts, and more pole pieces 1 can be cut out with fewer cuts, than applying the first coating 12 only in the first coating region 1011.

In the above technical solution, the first coating 12 is disposed on the surfaces of the first coating area 1011 and the second coating area 1012, so that the first coating 12 is disposed on the surface of the main body 101, which is beneficial to simplifying the preparation process of the pole piece 1 and accelerating the production rhythm.

In some embodiments, the volume particle size distribution Dv50 of the microcapsules 2 satisfies: dv50 is less than or equal to 0.5 μm and less than or equal to 10 μm.

For example, the volume particle size distribution Dv50 of the microcapsule 2 is 0.5 μm,1 μm,3 μm,5 μm,8 μm,10 μm or any value within the above range.

In the case where the volume particle diameter distribution Dv50 of the microcapsules 2 is not less than 0.5 μm, the risk of agglomeration of the microcapsules 2 during the preparation of the first coating layer 12 can be reduced; in the case where the volume particle diameter distribution Dv50 of the microcapsules 2 does not exceed 10 μm, the risk of the thickness of the first coating layer 12 being difficult to control during the coating process due to the larger particle diameter of the microcapsules 2 can be reduced.

In some embodiments, the volume particle size distribution Dv50 of the microcapsules 2 satisfies: dv50.ltoreq.2μm.ltoreq.6μm, for example 2 μm,3 μm,4 μm,6 μm or any value within the above-mentioned range. In this way, both the risk of agglomeration of the microcapsules 2 is reduced and the preparation of the first coating 12 is facilitated.

In some embodiments, the total thickness d1 of the first coating 12 satisfies: d1 is more than or equal to 2 mu m and less than or equal to 10 mu m. For example d1 is 2 μm,4 μm,8 μm,10 μm or any value within the above range.

In the case where the first coating layers 12 are provided on both side surfaces of the main body portion 101 in the thickness direction of the pole piece 1, the total thickness d1 of the first coating layers 12 may be the sum of the thicknesses of the two first coating layers 12, that is, d1=d11+d12; in the case where the first coating layer 12 is provided on the surface of one side of the main body portion 101, the total thickness d1 of the first coating layer 12 is the thickness of the first coating layer 12.

The thickness of the first coating layer 12 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 12 is not less than 2 μm, more microcapsules 2 in the first coating layer 12 are generated during the cutting of the current collector 10 provided with the first coating layer 12, so that more microcapsules 2 are broken, the core 22 can flow to the burrs and the exposed end face 1011a of the current collector 10, which is favorable for forming a relatively uniform insulating layer 13 to uniformly and densely cover the exposed end face 1011a and the burrs; in the case where the total thickness d1 of the first coating layer 12 does not exceed 10 μm, it is advantageous to reduce the space occupied by the first coating layer 12 and to increase the energy density of the battery cell.

In some embodiments, the total thickness d1 of the first coating 12 satisfies: 2 μm.ltoreq.d1.ltoreq.6μm, for example 2 μm,3 μm,4 μm,6 μm or any value within the above-mentioned range. Thus, the energy density of the battery cell can be advantageously increased, and the insulating layer 13 can be formed more uniformly.

In some embodiments, the adhesion force F between the first coating 12 and the current collector 10 satisfies: f is more than or equal to 20N/m and less than or equal to 100N/m; optionally, F satisfies: f is more than or equal to 70N/m and less than or equal to 80N/m. For example, F is 20N/m,60N/m,70N/m,75N/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 12 and the current collector 10 may reduce the risk of the first coating 12 falling off the current collector 10.

In some embodiments, the mass content a of the microcapsules 2, based on the total mass of the first coating 12, satisfies: a is more than or equal to 30wt% and less than or equal to 40wt%. For example, A is 30wt%,35wt%,40wt% or any value within the above range.

By setting the mass content A of the microcapsule 2 to 30-40 wt%, the uniform and compact insulating layer 13 is formed on the exposed end face 1011a of the cut current collector 10.

In some embodiments, the mass content D of the core material 22, based on the mass ratio of the microcapsules 2, satisfies: d is more than or equal to 60wt% and less than or equal to 80wt%. For example, D is 60wt%,65wt%,70wt%,75wt%,80wt%, or any value within the above range.

In the case where the mass content of the core material 22 satisfies the above range, the core material 22 is present in the microcapsule 2 in an appropriate content, and the core material 22 is present in the first coating layer 12 in an appropriate content, so that the core material 22 in an appropriate content flows out when the microcapsule 2 breaks, and flows to the end face 1011a to form the relatively uniform and dense insulating layer 13. For example, the insulating layer 13 having a proper thickness and completely covering the end face 1011a can be obtained.

In some embodiments, the materials of the housing 21 include: at least one of melamine-urea formaldehyde resin, melamine-urea formaldehyde copolycondensation resin, the material of the core material 22 includes: at least one of oleum Verniciae Fordii, catalpa oil and oleum Lini.

The microcapsules 2 of the embodiments of the present application may be commercially available, and specific kinds of materials thereof include, but are not limited to.

In the above technical solution, the shell 21 and the core 22 are both made of insulating materials, so that the core 22 is convenient to flow out when the shell 21 is subjected to external shearing force; the core 22 includes the above-described insulating substance that can flow, and after the insulating substance flows out of the case 21, can flow to the end face 1011a and solidify at the end face 1011 a.

In some embodiments, the first coating 12 further includes a conductive agent, the mass content B of which satisfies, based on the total mass of the first coating 12: b is more than or equal to 30wt% and less than or equal to 40wt%. For example, B is 30wt%,35wt%,40wt% or any value within the above range.

As an example, in the pole pieces shown in fig. 6 to 8, and fig. 9 to 11, the first coating layer 12 includes a conductive agent, and the surface of the tab 102 is not provided with the first coating layer 12.

In the above technical solution, by setting the conductive agent, the first coating 12 has a certain conductivity, and the current collector 10 provided with the first coating 12 has a certain conductivity, so that the influence of the microcapsule 2 on the conductivity of the pole piece 1 can be reduced.

In some embodiments, the ratio of the sheet resistance R1 of the current collector 10 to the sheet resistance R2 of the current collector 10 provided with the first coating 12 satisfies: r1 is more than or equal to 1, and R2 is more than or equal to 1.3. For example R1R 2 is 1,1.2,1.3 or any value within the above range.

The sheet resistance may be a resistance per unit area.

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

The sheet resistance R2 of the current collector 10 provided with the first coating layer 12 may be the sheet resistance of the current collector 10 provided with the first coating layer 12 but not provided with the second coating layer 11.

In the above embodiment, the current collector 10 provided with the first coating layer 12 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 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 referred to as SP, and the carbon nanofibers may also be referred to as VGCF.

The conductive carbon has good conductivity and does not react with the microcapsules, and the conductive carbon is used as a conductive agent, which is advantageous for improving the conductivity of the first coating 12.

In some embodiments, the first coating 12 further comprises a binder, the mass content C of the binder, based on the total mass of the first coating 12, satisfying: c is more than or equal to 20wt% and less than or equal to 40wt%; optionally, C satisfies: c is more than or equal to 30wt% and less than or equal to 40wt%. For example, C is 20wt%,30wt%,35wt%,40wt% or any value within the above range.

In the above technical solution, the microcapsule 2 can be adhered to the surface of the current collector 10 by setting the binder, and the risk of the first coating 12 falling off from the current collector 10 can be reduced by reasonably setting the mass content of the binder and having a proper adhesion between the first coating 12 and the current collector 10.

Fig. 12 is a schematic view of a pole piece according to an embodiment of the present application, fig. 13 is a sectional view taken along A-A in fig. 12, and fig. 14 is a sectional view taken along B-B in fig. 12.

In some embodiments, as shown in connection with fig. 12 to 14, the second coating 11 is disposed on the surface of the second coating region 1012, and the first coating 12 is disposed on the surface of the first coating region 1011 and a portion of the surface of the tab 102.

In this embodiment, the first coating 12 is not disposed on the surface of the second coating region 1012, and the first coating 12 does not include a conductive agent therein.

In the above embodiment, the first coating 12 is disposed on a part of the surface of the tab 102, so that the risk of short circuit caused by overlapping of the electrode with the opposite polarity on the part of the surface of the tab 102 can be reduced.

In some embodiments, the pole piece 1 further comprises an insulating layer 13, the insulating layer 13 being provided at the end face 1011a of the body portion 101 at the first end. In this way, the insulating layer 13 can cover the end face 1011a, reducing the risk of short circuits caused by overlapping of the end face 1011a with electrodes of opposite polarity.

In some embodiments, the material of core 22 further comprises: a drier. For example, the material of the core 22 includes tung oil and a drier.

The drier may be a substance that increases the curing speed of the oily material. For example, the drier acts to dry the unsaturated oil during its film formation.

The drier comprises: at least one of rare earth isooctanoate and cobalt isooctanoate. The drier can accelerate the solidification of the liquid insulating substance, so that the substance flowing out of the broken microcapsule 2 can be promoted to solidify at the end face 1011a to form the insulating layer 13.

In some embodiments, pole piece 1 comprises a positive pole piece. 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.

Optionally, the current collector comprises aluminum foil.

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.

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-mentioned binder has a good adhesive property, and facilitates adhesion of the microcapsules to the surface of the current collector 10.

The technical solution of the pole piece is described above in connection with fig. 1 to 14, and the preparation method of the pole piece is described below in connection with fig. 15, 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. 15 is a schematic view of a method of manufacturing 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.

In step 210, a first slurry is applied to a first application region 1011 of the current collector 10 to form a first coating layer 12, the first slurry including microcapsules 2, the microcapsules 2 including a core 22 and a shell 21 surrounding the core 22, the material of the shell 21 including a polymer, and the material of the core 22 including a liquid insulating substance.

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.

Alternatively, in step 210, the first paste may be applied only in the first coating region 1011, or the first paste may be applied in both the first coating region 1011 and the second coating region 1012.

At step 220, a second slurry is applied to the second application region 1012 of the current collector 10 to form a second coating 11, the second slurry including an 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; by the addition of the conductive agent, the second coating layer 11 can be made to have a certain conductivity.

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 230, the current collector 10 provided with the first coating 12 and the second coating 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 part of the cutting line 124 is disposed in the first coating region 1011 such that, during the cutting process, the cutting tool passes through the first coating region 1011, the microcapsules 2 of the first coating region 1011 are broken, the core material 22 flows out, flows to the end face 1011a produced by the cutting and is cured at the end face 1011a to form the insulating layer 13.

In the above technical solution, the pole piece 1 prepared by the method 200 is beneficial to improving the cycle performance of the battery cell when being used for the battery cell.

In some embodiments, the method 200 further comprises: the second paste is applied to the first coating region 1011 of the current collector 10 to form the second coating layer 11.

The second coating 11 is disposed in the first coating region 1011 and the second coating region 1012 of the current collector 10, and the prepared pole piece 1 includes more active materials than the second coating 11 coated only in the first coating region 1011, which is beneficial to improving the energy density of the battery cell.

In some embodiments, the method 200 further comprises: the first slurry is applied in a second application region 1012 of the current collector 10 to form a first coating 12.

The first coating 12 is disposed in the first coating region 1011 and the second coating region 1012 of the current collector 10, and compared with the case where the first coating 12 is only coated in the first coating region 1011, the case where the first coating 12 is coated in the first coating region 1011 and the second coating region 1012 is advantageous for reducing the number of cutting times, and more pole pieces 1 can be cut out by fewer cutting times.

In some embodiments, the volume particle size distribution Dv50 of the microcapsules 2 satisfies: dv50 is less than or equal to 0.5 mu m and less than or equal to 10 mu m; alternatively, the volume particle size distribution Dv50 of the microcapsules 2 satisfies: dv50 is less than or equal to 2 mu m and less than or equal to 6 mu m.

In some embodiments, the total thickness d1 of the first coating 12 satisfies: d1 is more than or equal to 2 mu m and less than or equal to 10 mu m; alternatively, d1 satisfies: d1 is less than or equal to 2 mu m and less than or equal to 6 mu m.

In some embodiments, the mass content a of the microcapsules 2, based on the total mass of the first slurry, satisfies: a is more than or equal to 30wt% and less than or equal to 40wt%.

Alternatively, the mass content D of the core material 22, based on the total mass of the microcapsules 2, satisfies: d is more than or equal to 60wt% and less than or equal to 80wt%.

Optionally, the materials of the housing 21 include: at least one of melamine resin, urea resin, melamine-urea-formaldehyde copolycondensation resin, the material of the core material 22 includes: at least one of oleum Verniciae Fordii, catalpa oil and oleum Lini.

In some embodiments, the material of core 22 further comprises: a drier. The drier comprises: at least one of rare earth isooctanoate and cobalt isooctanoate.

In some embodiments, the first paste further comprises a conductive agent and a binder.

The first coating layer 12 can have a certain conductivity by adding a conductive agent; the microcapsules and the conductive agent are easily adhered to the surface of the current collector 10 by the addition of the adhesive.

The mass content B of the conductive agent satisfies, based on the total mass of the first paste: b is more than or equal to 30wt% and less than or equal to 40wt%, and the mass content C of the binder satisfies the following conditions: c is more than or equal to 20wt% and less than or equal to 40wt%. By reasonably setting the mass content of the conductive agent and the mass content of the binder, the current collector 10 provided with the first coating layer 12 has a suitable surface resistance, the battery cell has a smaller resistance, and at the same time, the first coating layer 12 and the current collector 10 have a suitable adhesive force therebetween.

In some embodiments, step 210 comprises: the first paste is applied by gravure coating to the first coating region 1011 of the current collector 10 to form the first coating layer 12. The first coating 12 is conveniently prepared in a reduced thickness 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 12 is achieved by the cooperation of the gravure roll, the pressure roll, and the doctor blade.

In some embodiments, step 230 comprises: the cutter is controlled to cut the current collector 10 provided with the first coating 12 and the second coating 11 along the cut line.

For example, a slitting circular knife or a knife blade punch may be used to slit the current collector 10.

In the process of cutting using a cutter, the cutter may cut the microcapsules 2 located on the cutting line, so that the core material 22 in the microcapsules 2 flows out to the cut end face 1011a to form the insulating layer 13.

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, graphene.

[ 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. 16 is a schematic view of a battery cell according to an embodiment of the application. For example, as shown in fig. 16, 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. 16, 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 (may also be the tab 102 of the electrode sheet 1) 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. 17 is a schematic view of a battery according to an embodiment of the present application. As shown in fig. 17, 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. 18 is a schematic diagram of an electric device according to an embodiment of the application. As shown in fig. 18, 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 a structure as shown in fig. 9 to 11. In embodiment 1, the first coating 12 includes a first slurry including the microcapsules 2, the conductive agent, and the binder. The microcapsule 2 has a mass content a of 40wt% and the conductive agent has a mass content B of 30wt% and the binder has a mass content C of 30wt% based on the total mass of the first slurry. The microcapsule has a volume particle size distribution Dv50 of 2 μm and a mass content D of the core material of 60wt% based on the total mass of the microcapsule. The binder is polyacrylonitrile, the solvent is water, the conductive carbon is superconducting carbon SP, and the viscosity of the slurry is 300 mPas.

The total thickness d1 of the first coating 12 is 6 μm, the material of the outer shell of the microcapsule is urea formaldehyde resin, and the material of the core material is tung oil and cerium isooctanoate drier.

In embodiment 1, the first coating layer 12 is disposed on the surfaces of the first coating region 1011 and the second coating region 1012, and the second coating layer 11 is disposed on the surfaces of the first coating region 1011 and the second coating region 1012.

Examples 2 to 3

Examples 2-3 differ from example 1 in that: the mass content D of the core material is different based on the total mass of the microcapsules.

Examples 4 to 6

Examples 4-6 differ from example 1 in that: the volume particle size distribution Dv50 of the microcapsules is different.

Examples 7 to 9

Examples 7-9 differ from example 1 in that: the total thickness d1 of the first coating 12 is different.

Examples 10 to 15

Examples 10-15 differ from example 1 in that: the mass content a of the microcapsules 2, the mass content B of the conductive agent, and the mass content C of the binder are different based on the total mass of the first slurry.

Example 16

Example 16 differs from example 1 in that: the pole pieces are different in structure. The pole piece in example 16 has the structure shown in fig. 6 to 8. In example 16, the first coating layer 12 is disposed on the surface of the first coating region 1011 and the second coating layer 11 is disposed on the surfaces of the first coating region 1011 and the second coating region 1012.

Example 17

Example 17 differs from example 1 in that: the pole pieces are different in structure. The pole piece of example 17 has the structure shown in fig. 12 to 14. In embodiment 17, the first coating layer 12 is disposed on the surface of the first coating region 1011 and a part of the surface of the tab 102, and the second coating layer 11 is disposed on the surface of the second coating region 1012.

Comparative example 1

Comparative example 1 differs from example 1 in that: the positions of the first coating layers were different, the substances included in the first coating layers were different, and comparative example 1 did not include an insulating layer.

Specifically, in comparative example 1, the first coating layer was provided on the surfaces of the first coating region and the portion of the tab (the portion near the first coating region, which has a width of 10mm, and the total width of the tab is 30 mm); the slurry of the first coating 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, d1 is the total thickness of the first coating layer, A is the mass content of the microcapsules added during the preparation process; 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 insulating 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. In table 2, a short circuit occurs at a part of the positions, and it may be said that a short circuit occurs at a position where the insulating layer 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

The microcapsule, the conductive agent and the binder are mixed according to a certain proportion, and the solvent is added and stirred uniformly, and the viscosity of the slurry is about 300 mPa.s. 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 was coated on an aluminum foil by gravure coating, leaving an empty foil of 30mm in width to prepare a tab, which was oven dried at 100 c, and the total thickness of the first coating after drying was as shown in table 1.

In examples 1-19, 10mm of the 30mm width of the tab need not be reserved for application of the first coating, and for example 20 10mm of the 30mm width of the tab need be reserved for application of the first coating.

And continuously coating a second slurry on the first coating or the current collector to prepare a second coating, 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) Die cutting

The above product is punched into a suitable size using a circular knife or a knife plate.

(4) Manufacturing battery monomer

And combining the positive electrode plate with other components required by the battery: the negative plate, the diaphragm and the electrolyte are assembled together to form the lithium ion battery monomer. 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 prepared empty foil is 30mm to prepare a tab, and 10mm width is reserved on the tab to coat a first coating (the first coating of the comparative example is different from the first coating of the embodiment of the application), and the slurry of the first coating comprises boehmite and a binder; a second coating was then prepared at the rest of the aluminum foil. The rest of the preparation method is the same as that of the embodiment, and is not repeated here.

[ confirmation of insulating layer ]

The end face was observed by a Scanning Electron Microscope (SEM) to see whether an insulating layer was present at the end face. In addition, the thickness of the 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 die-cut end surface to overlap the full charge anode, and observing whether a short circuit exists.

[ test of whether microcapsules are broken or not at the time of Rolling ]

And testing the surface resistance of the rolled sample by using a pole piece resistance meter, and confirming whether the microcapsule is broken during rolling. Under the condition that the surface resistance of the pole piece after rolling is larger than that of the pole piece before rolling, the microcapsule is broken.

[ 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 an insulating layer on one side of the pole piece. A plate with an adhesive coated area is selected as a second substrate, which is glued to the 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.

[ test of particle size of microcapsules ]

The volume particle size distribution of the microcapsules can be determined by means of a particle size analyzer-laser diffraction method, and in particular, reference can be made to the standard GB/T19077-2016, using a laser diffraction scattering particle size analyzer, measured according to the manufacturer's instructions. For example, prior to preparing the slurry of the first coating, an appropriate amount of microcapsules was taken and the volumetric particle size distribution of the material was tested using a malvern 2000 (MasterSizer 2000) laser particle sizer. Taking a proper amount of a sample to be detected (the concentration of the sample is ensured to be 8-12% of the shading degree), adding 20ml of deionized water, simultaneously exceeding 5 minutes (53 KHz/120W) to ensure that the sample is completely dispersed, and then measuring the sample according to the GB/T19077-2016/ISO 13320:2009 standard.

For another example, the pole piece may be tested using a scanning electron microscope to obtain an image of the area of the first coating of the pole piece. Selecting a region with a specific size, and calculating the volume particle size distribution Dv50 of the microcapsules according to the number and the size of the microcapsules in the image.

[ mass ratio of microcapsule, conductive agent and binder ]

The mass ratio can be obtained according to the mass of the microcapsule, the mass of the conductive agent and the mass of the binder added in the preparation process.

[ test of liquid retention Rate of Pole piece ]

And testing the liquid retention rate of the pole piece after the pole piece is cut. After the pole piece is cut, the pole piece is weighed, then soaked in electrolyte for standing at 25 ℃ for 8 hours, and then taken out for weighing. Retention = weight after pole piece soaking/weight before soaking.

[ test of cycle Performance ]

After the battery cell was prepared, the capacity retention rate of the battery cell was measured for 500 cycles.

The battery cell is subjected to charge and discharge test, specifically, the cycle test is carried out under the conditions of 45 ℃ and 1C/1C.

The arrangement of the microcapsules according to the embodiment of the application, which is shown in examples 1 to 17 and comparative example 1, is advantageous for improving the liquid retention rate of the pole piece and the cycle performance of the battery cell.

As shown in examples 1-2, the mass ratio of the core material in the microcapsules was properly set, which is advantageous in obtaining a relatively uniform insulating layer and in that the microcapsules are less likely to crack during rolling. As shown in example 3, when the mass of the core material is relatively small, it is difficult to flow out enough core material to completely and uniformly coat the end face, and when the end face is overlapped with the full charge anode, a short circuit occurs at the end face not coated with the insulating layer. In the case where D is not more than 80wt% as shown in the combination of example 2, the outer shell of the microcapsule has a proper thickness in the case where the mass ratio of the core material is proper, and the risk of the outer shell of the microcapsule being low in strength due to the low thickness of the microcapsule can be reduced, and the microcapsule is not broken at the time of rolling.

Reasonable setting of the volume particle size distribution Dv50 of the microcapsules facilitates the preparation of the first coating, as shown in examples 4-6. Under the condition that the volume particle size distribution Dv50 of the microcapsules is not less than 0.5 mu m, the microcapsules are not easy to agglomerate, and the risk that the first coating is difficult to prepare due to the agglomeration of the microcapsules can be reduced; in the case that the volume particle size distribution Dv50 of the microcapsules does not exceed 10 μm, the particle size of the microcapsules is not excessively large, so that the risk that scratches exist in the preparation process of the first coating layer due to the excessively large particle size, and the first coating layer with uniform thickness is difficult to prepare can be reduced. The increase in particle size of the microcapsules, shown in examples 1 and 4-6, helps to improve the liquid retention and cycle performance of the pole pieces.

As shown in the combined embodiments 7-8, the thickness of the first coating is reasonably set, so that a relatively uniform insulating layer is obtained, and short circuit is avoided when the end face is overlapped with the full charge anode. As shown in example 9, the first coating layer had a smaller thickness, the microcapsule content was smaller, and it was difficult to flow out enough core material to completely and uniformly obtain the clad end face, and when the end face was overlapped with the full charge anode, the short circuit did not occur at the partial position, and the short circuit did not occur at the end face not clad with the insulating layer.

By reasonably setting the proportion of the microcapsules, the conductive agent and the binder in the first coating in combination with the examples 10-12, the pole piece and the battery cell with better comprehensive performance can be obtained. As shown in example 13, in the case where the mass content of the conductive agent is small, the area resistance of the current collector provided with the first coating layer increases more, and the resistance of the battery cell increases, which is disadvantageous for improvement of the rate performance of the battery cell. In the case of the microcapsule having a small mass content, as shown in example 14, it was difficult to flow out enough core material to completely and uniformly obtain the coated end face, and when the end face was overlapped with the full charge anode, the short circuit was not generated at a part of the position, and the short circuit was generated at the end face not coated with the insulating layer. As shown in the combination example 15, in the case that the mass content of the binder is small, the binding force between the first coating layer and the current collector is small, and the first coating layer partially falls off after being immersed in the electrolyte, so that the battery cell cannot be prepared. The increase in mass content of the microcapsules, as shown in examples 1 and 10, helps to improve the liquid retention and cycle performance of the pole pieces.

The pole pieces can have a variety of different configurations as shown in connection with examples 16-17. As shown in the combination embodiments 16 and 17, the first coating layer is not disposed on the surface of the tab, and the second coating layer is disposed in both the first coating region and the second coating region, which is favorable for improving the capacity of the battery cell, and can improve the volumetric energy density of the battery cell under the condition that the battery cells have the same volume.

It should be noted that, although the table of the embodiment uses only the positive electrode sheet in which the positive electrode current collector is an aluminum foil as an example, the solution of the present application may be applied to the negative electrode sheet and the positive electrode sheet made of other materials. In addition, although the microcapsules in the tables of examples are filled with a drier, microcapsules not filled with a drier are also applicable.

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 positive electrode sheet, characterized by comprising: a current collector, a first coating and a second coating;

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, the first coating area is arranged between the second coating area and the tab, and the tab is prepared by cutting the current collector;

At least part of the first coating is arranged on the surface of the first coating area, the first coating comprises a microcapsule, the microcapsule comprises a core material and a shell for coating the core material, the material of the shell comprises a polymer, the material of the core material comprises a liquid insulating substance, and the liquid insulating substance is oxidized into a solid film after encountering air;

at least a portion of the second coating is disposed on a surface of the second coating region, the second coating including an active substance.

2. The positive electrode tab of claim 1 wherein the second coating is disposed on the surfaces of the first and second coating regions and the first coating is disposed on the surface of the first coating region.

3. The positive electrode tab of claim 1, wherein the second coating is disposed on surfaces of the first and second coating regions, and the first coating is disposed on surfaces of the first and second coating regions.

4. The positive electrode sheet according to claim 1, wherein the microcapsule has a volume particle size distribution Dv50 satisfying: dv50 is less than or equal to 0.5 μm and less than or equal to 10 μm.

5. The positive electrode sheet according to claim 4, wherein the microcapsule has a volume particle size distribution Dv50 satisfying: dv50 is less than or equal to 2 mu m and less than or equal to 6 mu m.

6. The positive electrode sheet according to claim 1, wherein the total thickness d1 of the first coating layer satisfies: d1 is more than or equal to 2 mu m and less than or equal to 10 mu m.

7. The positive electrode sheet according to claim 6, wherein the total thickness d1 of the first coating layer satisfies: d1 is less than or equal to 2 mu m and less than or equal to 6 mu m.

8. The positive electrode tab of claim 1 wherein the bond force F between the first coating and the current collector satisfies: f is more than or equal to 20N/m and less than or equal to 100N/m.

9. The positive electrode tab of claim 8 wherein the bond force F between the first coating and the current collector satisfies: f is more than or equal to 70N/m and less than or equal to 80N/m.

10. The positive electrode sheet according to claim 1, wherein the mass content a of the microcapsules, based on the total mass of the first coating layer, satisfies: a is more than or equal to 30wt% and less than or equal to 40wt%.

11. The positive electrode sheet according to claim 1, wherein the mass content D of the core material, based on the total mass of the microcapsules, satisfies: d is more than or equal to 60wt% and less than or equal to 80wt%.

12. The positive electrode tab of claim 1 wherein the material of the housing comprises: at least one of melamine resin, urea resin and melamine-urea-formaldehyde copolycondensation resin, wherein the material of the core material comprises: at least one of oleum Verniciae Fordii, catalpa oil and oleum Lini.

13. The positive electrode sheet according to claim 1, wherein the first coating layer further comprises a conductive agent, the mass content B of the conductive agent satisfying, based on the total mass of the first coating layer: b is more than or equal to 30wt% and less than or equal to 40wt%.

14. The positive electrode tab according to claim 1, wherein a ratio of a sheet resistance R1 of the current collector to a sheet resistance R2 of the current collector provided with the first coating layer satisfies: r1 is more than or equal to 1, and R2 is more than or equal to 1.3.

15. The positive electrode sheet of claim 13, wherein the conductive agent comprises conductive carbon.

16. The positive electrode sheet of claim 15, wherein the conductive carbon comprises at least one of carbon black, superconducting carbon, carbon nanofibers, carbon nanotubes, graphene.

17. The positive electrode sheet according to claim 1, wherein the first coating layer further comprises a binder, the mass content C of the binder, based on the total mass of the first coating layer, satisfying: c is more than or equal to 20wt% and less than or equal to 40wt%.

18. The positive electrode sheet according to claim 17, wherein the mass content C of the binder satisfies: c is more than or equal to 30wt% and less than or equal to 40wt%.

19. The positive electrode tab of claim 1, wherein the second coating is disposed on a surface of the second coating region and the first coating is disposed on a surface of the first coating region and a portion of a surface of the tab.

20. The positive electrode tab of claim 1 further comprising an insulating layer disposed on an end face of the body portion at the first end.

21. The positive electrode sheet according to claim 1, wherein the material of the core material further comprises: a drier.

22. The positive electrode sheet of claim 21, wherein the drier comprises: at least one of rare earth isooctanoate and cobalt isooctanoate.

23. The positive electrode tab of claim 1 wherein the current collector comprises aluminum foil.

24. The positive electrode sheet according to claim 1, wherein the positive electrode sheet comprises a positive electrode active material comprising LiNi _0.8 Co _0.1 Mn _0.1 O ₂ 。

25. A method of producing the positive electrode sheet as claimed in claim 1, comprising:

coating a first slurry on a first coating area of a current collector to form a first coating, wherein the first slurry comprises a microcapsule, the microcapsule comprises a core material and a shell for coating the core material, the material of the shell comprises a polymer, the material of the core material comprises a liquid insulating substance, and the liquid insulating substance is oxidized into a solid film after encountering air;

Coating a second slurry on a second coating region of the current collector to form a second coating layer, wherein the second slurry comprises an active substance;

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

26. The method of claim 25, wherein the method further comprises:

the second slurry is coated on the first coating region of the current collector to form the second coating layer.

27. The method of claim 25, 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 25, wherein the microcapsule has a volume particle size distribution Dv50 that satisfies: dv50 is less than or equal to 0.5 μm and less than or equal to 10 μm.

29. The method of claim 28, wherein the microcapsule has a volume particle size distribution Dv50 that satisfies: dv50 is less than or equal to 2 mu m and less than or equal to 6 mu m.

30. The method of claim 25, wherein the total thickness d1 of the first coating satisfies: d1 is more than or equal to 2 mu m and less than or equal to 10 mu m.

31. The method of claim 30, wherein the total thickness d1 of the first coating satisfies: d1 is less than or equal to 2 mu m and less than or equal to 6 mu m.

32. The method according to claim 25, wherein the mass content a of the microcapsules, based on the total mass of the first slurry, satisfies: a is more than or equal to 30wt% and less than or equal to 40wt%.

33. The method according to claim 25, wherein the mass content D of the core material, based on the total mass of the microcapsules, satisfies: d is more than or equal to 60wt% and less than or equal to 80wt%.

34. The method of claim 25, wherein the material of the housing comprises: at least one of melamine resin, urea resin and melamine-urea-formaldehyde copolycondensation resin, wherein the material of the core material comprises: at least one of oleum Verniciae Fordii, catalpa oil and oleum Lini.

35. The method of claim 25, wherein the first slurry further comprises a conductive agent and a binder, the mass content B of the conductive agent, based on the total mass of the first slurry, satisfying: b is more than or equal to 30wt% and less than or equal to 40wt%, and the mass content C of the binder satisfies the following conditions: c is more than or equal to 20wt% and less than or equal to 40wt%.

36. The method of claim 25, wherein the material of the core material further comprises: a drier.

37. The method of claim 36, wherein the drier comprises: at least one of rare earth isooctanoate and cobalt isooctanoate.

38. The method of claim 25, 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.

39. The method of claim 25, wherein the cutting the current collector provided with the first coating and the second coating along the cut line comprises:

and controlling a cutter to cut the current collector provided with the first coating and the second coating along the cutting line.

40. A battery cell comprising the positive electrode sheet of any one of claims 1-24, and/or the positive electrode sheet prepared by the method of any one of claims 25-39.

41. A battery comprising the battery cell of claim 40.

42. An electrical device comprising a battery according to claim 41.