CN219350608U - Pole piece, electrode assembly, battery monomer, battery and electric equipment - Google Patents

Abstract

The application provides a pole piece, electrode assembly, battery monomer, battery and consumer. The pole piece comprises a current collector, an active material layer and an insulating layer. The active material layer is disposed on one side or both sides of the current collector in the thickness direction. The active material layer comprises a main body region and a thinning region, wherein the thinning region is positioned at the end part of the main body region along the width direction of the current collector, and the thickness of the thinning region is smaller than that of the main body region. The insulating layer covers at least a portion of the thinned region in a thickness direction of the current collector. When the battery cell applying the pole piece is horizontally placed or obliquely placed, lithium can be released from a thinning area of the negative pole piece close to the lower part of the battery cell.

Description

Pole piece, electrode assembly, battery monomer, battery and electric equipment

Technical Field

The application relates to the technical field of battery manufacturing, in particular to a pole piece, an electrode assembly, a battery monomer, a battery and electric equipment.

Background

Energy conservation and emission reduction are key to sustainable development of the automobile industry, and electric vehicles become an important component of sustainable development of the automobile industry due to the energy conservation and environmental protection advantages of the electric vehicles. For electric vehicles, battery technology is an important factor in the development of the electric vehicles.

The lithium ion battery as a rechargeable battery has the advantages of small volume, high energy density, high power density, multiple recycling times, long storage time and the like.

In the development of battery technology, how to improve the cycle life of a battery and ensure the running stability and safety of a battery cell is one of the important research points in the field.

Disclosure of Invention

The utility model aims to provide a pole piece, electrode assembly, battery monomer, battery and consumer to solve when battery monomer uses, the problem of lithium is analyzed in the attenuate district of the negative pole piece that is located the lower part.

In a first aspect, embodiments of the present application provide a pole piece, including: a current collector; the active material layer is arranged on one side or two sides of the thickness direction of the current collector, the active material layer comprises a main body region and a thinning region, the thinning region is positioned at the end part of the main body region along the width direction of the current collector, and the thickness of the thinning region is smaller than that of the main body region; and an insulating layer covering at least a portion of the thinned region in a thickness direction of the current collector.

In the technical scheme, the electrolyte is used as a carrier for lithium ion transmission, and the electrolyte is lost along with the charge and discharge of the battery monomer, so that the electrolyte cannot fully soak the inside of the battery monomer. When the battery monomer is horizontally placed or obliquely placed, the electrolyte is positioned at the lower part of the battery monomer under the action of gravity, so that the thinning area positioned at the upper part of the battery monomer is not soaked by the electrolyte, lithium ions lack of a transmission path embedded into the thinning area at the upper part of the battery monomer, and then lithium ions are enriched at the lower part of the battery monomer, and lithium is separated from the position of the thinning area of the negative electrode plate at the lower part of the battery monomer. Therefore, the insulating layer is arranged at the position of the thinning area to play an insulating role, and a barrier can be formed on a transmission path of the thinning area of the lower part of the lithium ion embedded battery monomer, so that the possibility of lithium analysis in the thinning area at the lower end when the battery is horizontally placed or obliquely placed is reduced.

In some embodiments, the insulating layer completely covers the thinned region.

In the technical scheme, the insulating layer completely covers the thinning area, so that the barrier degree of the thinning area of the lithium ion transmission embedded negative electrode plate is increased, and the possibility of lithium separation in the thinning area of the negative electrode plate positioned at the lower part of the battery cell can be greatly reduced when the battery cell is horizontally placed or obliquely placed.

In some embodiments, the thinned region tapers in thickness in a direction away from the body region.

In the above technical scheme, along the direction deviating from the main body region, the thickness of the thinned region gradually decreases to reduce the possibility of cracking the active material layers at two ends in the width direction of the pole piece in the pole piece winding process.

In some embodiments, the insulating layer is of uniform thickness.

In the technical scheme, the thickness of the insulating layer is uniform, so that the production and the manufacture of the pole piece are facilitated, and the process difficulty of increasing the insulating layer in the thinning area of the pole piece is reduced.

In some embodiments, the body region has a first surface facing away from the current collector, and the insulating layer has a second surface facing away from the current collector, the first surface being flush with the second surface.

In the technical scheme, the first surface is flush with the second surface, so that the electrode plate interface is conveniently improved, the gap caused by the thinning area is reduced, when the battery monomer is horizontally or obliquely placed, electrolyte is soaked into the thinning area of the negative electrode plate on the upper part of the battery monomer as much as possible, lithium ions are conveniently inserted into the thinning area of the negative electrode plate on the upper part of the battery monomer, the enrichment amount of lithium ions on the lower part of the battery monomer is reduced, and the possibility of lithium analysis in the thinning area of the negative electrode plate on the lower part of the battery monomer is reduced.

In some embodiments, an end of the insulating layer facing away from the body region is flush with an end of the thinned region facing away from the body region in a width direction of the current collector.

In the technical scheme, the size of the insulating layer in the width direction of the pole piece is reduced, and the occupied area of the current collector is reduced.

In some embodiments, an end of the insulating layer facing away from the body region exceeds an end of the thinned region facing away from the body region in a width direction of the current collector.

In the technical scheme, the barrier degree of the thinning area of the lithium ion transmission embedded negative electrode plate can be increased, and the possibility of lithium separation in the thinning area of the negative electrode plate positioned at the lower part of the battery cell can be further reduced when the battery cell is horizontally placed or obliquely placed.

In some embodiments, the insulating layer is an insulating tape or an insulating coating.

In the technical scheme, the insulating layer is simple in structure, and the difficulty of the pole piece production process is reduced.

In some embodiments, the thickness of the insulating layer is H in the thickness direction of the pole piece ₁ Meets the requirement that H is more than or equal to 20um ₁ ≤60um。

In the technical scheme, if the thickness of the insulating layer is smaller than 20um, the thickness of the insulating layer is small and the insulating effect is poor; if the thickness of the insulating layer is larger than 60um, the thickness of the insulating layer is too large, the insulating layer and the main body area form a step shape, the pole piece is easy to wrinkle at the step, the pole piece interface is affected, and potential safety hazards are caused. Therefore, the thickness of the insulating layer satisfies that 20 um.ltoreq.H ₁ The thickness of the insulating layer is less than or equal to 60um, and the insulating layer has a certain thickness and is relatively highGood insulating effect, and no influence on the interface of the pole piece.

In some embodiments, the width of the thinned region is W along the width direction of the pole piece, and is more than 0mm and less than or equal to 14mm.

In the above technical scheme, if the width of the thinning area is equal to 0, the thinning area does not exist, and the possibility of cracking the active material layer at the edge of the pole piece in the pole piece winding process can not be reduced through the thinning area. Under the condition that the current collector has a certain dimension along the width direction, if the thinning area is larger than 14mm, the thinning area occupies an oversized coating area of the current collector, and the energy density of the battery cell is affected; therefore, W is more than 0mm and less than or equal to 14mm, an active material layer at the edge of the pole piece is not easy to crack in the pole piece winding process, and meanwhile, the battery monomer has higher energy density.

In some embodiments, the pole piece is a negative pole piece.

In the technical scheme, the insulating layer is directly arranged in the thinning area of the negative electrode plate, and can directly block the transmission path of lithium ions in the thinning area of the negative electrode plate. And the possibility of lithium analysis in a thinning area of the negative electrode plate at the bottom of the battery cell is reduced in the process of horizontally or obliquely placing the battery cell.

In a second aspect, embodiments of the present application provide an electrode assembly comprising a pole piece according to any of the embodiments of the first aspect.

In a third aspect, embodiments of the present application provide a battery cell comprising the pole piece of the embodiments of the second aspect.

In a fourth aspect, embodiments of the present application provide a battery comprising the battery cell of the embodiments of the third aspect.

In a fifth aspect, embodiments of the present application provide a powered device, including the battery of the fourth aspect, the battery being configured to power the powered device.

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 will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic illustration of a vehicle according to some embodiments of the present application;

fig. 2 is a schematic structural diagram of a battery provided in some embodiments of the present application;

FIG. 3 is an exploded view of a battery cell according to some embodiments of the present application;

FIG. 4 is a schematic view of an electrode assembly according to some embodiments of the present application;

FIG. 5 is a cross-sectional view taken along line A-A of FIG. 4;

fig. 6 is a schematic structural diagram of a pole piece after being unfolded according to some embodiments of the present application;

FIG. 7 is a schematic cross-sectional structural view taken along B-B of FIG. 6;

FIG. 8 is another cross-sectional structural schematic view taken along B-B of FIG. 6;

fig. 9 is a schematic view of yet another cross-sectional structure along B-B of fig. 6.

Icon: 121-pole pieces; 1-a current collector; 2-an active material layer; 21-a body region; 211-a first surface; 22-thinning areas; 3-an insulating layer; 31-a second surface; 12-an electrode assembly; 121 A-A positive pole piece; 121 b-a negative electrode piece; 122-a membrane; 123-gap; 100-cell; 10-battery cell; 11-end caps; 13-a housing; 20-a box body; 201-a first part; 202-a second part; 203-an accommodation space; 1000-vehicle; 200-motor; 300-a controller; y-width direction; z-thickness direction; x-length direction.

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having" and any variations thereof in the description and claims of the present application and in the description of the figures above are intended to cover non-exclusive inclusions. The terms first, second and the like in the description and in the claims or in the above-described figures, are used for distinguishing between different objects and not necessarily for describing a particular sequential or chronological order.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "attached" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

The term "and/or" in this application is merely an association relation describing an associated object, and indicates that three relations may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone. In this application, the character "/" generally indicates that the associated object is an or relationship.

In the embodiments of the present application, the same reference numerals denote the same components, and in the interest of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, etc. dimensions of the various components in the embodiments of the present application, as well as the overall thickness, length, width, etc. dimensions of the integrated device, are illustrative only and should not be construed as limiting the present application in any way.

In the present application, the battery cell may include a lithium ion secondary battery, a lithium ion primary battery, a lithium sulfur battery, a sodium lithium ion battery, a sodium ion battery, a magnesium ion battery, or the like, which is not limited by the embodiment of the present application. The battery cells may be cylindrical, flat, rectangular, or otherwise shaped, as well as the embodiments herein are not limited in this regard. The battery cells are generally classified into three types according to the packaging method: the cylindrical battery cell, the square battery cell and the soft pack battery cell are not limited thereto.

Reference to a battery in embodiments of the present application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application may include a battery module or a battery pack, or the like. The battery generally includes a case for enclosing one or more battery cells. The case body can prevent liquid or other foreign matters from affecting the charge or discharge of the battery cells.

The battery cell comprises an electrode assembly and electrolyte, wherein the electrode assembly consists of a positive electrode plate, a negative electrode plate and a separation film. The battery cell mainly relies on metal ions to move between the positive pole piece and the negative pole piece to work. The positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer, wherein the positive electrode active material layer is coated on the surface of the positive electrode current collector, the positive electrode current collector without the positive electrode active material layer protrudes out of the positive electrode current collector coated with the positive electrode active material layer, and the positive electrode current collector without the positive electrode active material layer is used as a positive electrode lug. Taking a lithium ion battery as an example, the material of the positive electrode current collector may be aluminum, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate or the like. The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode active material layer is coated on the surface of the negative electrode current collector, the negative electrode current collector without the negative electrode active material layer protrudes out of the negative electrode current collector coated with the negative electrode active material layer, and the negative electrode current collector without the negative electrode active material layer is used as a negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon, silicon, or the like. In order to ensure that the high current is passed without fusing, the number of positive electrode lugs is multiple and stacked together, and the number of negative electrode lugs is multiple and stacked together. The material of the separator may be PP (polypropylene) or PE (polyethylene).

In the development of battery technology, how to improve the cycle life of a battery and ensure the running stability and safety of a battery cell is one of the important research points in the field.

The inventor researches and discovers that lithium precipitation is a common abnormal phenomenon of a lithium ion battery, and can influence the charging efficiency and the energy density of lithium ions, lithium crystals can be formed when the lithium precipitation is serious, and the lithium crystals can puncture a diaphragm to cause internal short circuit thermal runaway, so that the safety of the battery is seriously damaged, and the cycle life of the battery is influenced.

Typically, the electrode sheet includes a current collector and active material layers coated on both sides of the current collector. The pole piece involves the coating process in the production process, namely, paste containing active substances is coated on a current collector (such as a copper foil and other base materials) according to a certain weight, the thickness of the edge of an active substance layer is different from that of the middle area due to the flowing action of paste liquid, and then the active substance layer at the edge is dried earlier than that at the middle area, in the drying process of the active substance layer, the active substance layer which is not dried at the middle area flows towards the edge, the thickness of the active substance layer at the edge after drying is higher than that at the middle area, and the active substance layer at the area of the edge thickening of the pole piece of the structure is easy to be cracked in the cold pressing process. For this reason, the discharge of the paste in the edge region of the pole piece is reduced, and the edge (i.e., thinned region) of the active material layer after roll drying is smaller than that in the middle region, thereby reducing the possibility of the active material layer with thickened edge falling off and chapping during winding.

The inventors have further studied and found that the reason for lithium precipitation in a battery is that in a battery cell using the above-described pole piece having the thinned region, a gap exists at a position corresponding to the thinned region. The electrolyte is used as a carrier for lithium ion transmission, and the electrolyte is lost along with the charge and discharge of the battery cell, so that the electrolyte cannot fully impregnate the inside of the battery cell along with the loss of the electrolyte. When the battery cell is vertically placed (taking a cylindrical battery as an example, the axial direction of the cylindrical battery extends along the height direction), lithium ions diffuse in the overlap region due to the existence of overlap (the part of the negative electrode plate exceeding the positive electrode plate), and the lithium analysis phenomenon in the thinning region of the negative electrode plate is not obvious. However, when the battery monomer is horizontally placed or obliquely placed (taking a cylindrical battery as an example, the axial direction and the horizontal direction or the inclination direction of the cylindrical battery) and the electrolyte is positioned at the lower part of the battery monomer under the action of gravity, the gap part close to the upper part of the battery monomer is not filled with the electrolyte, the thinning region of the negative electrode plate corresponding to the gap part without the electrolyte filling is not soaked by the electrolyte, the transmission path of lithium ions entering the thinning region of the negative electrode plate at the upper part of the battery monomer is interrupted, the lithium ions lack a transmission path, cannot be embedded into the thinning region of the negative electrode plate corresponding to the gap part, and can be enriched at the lower part of the battery monomer under the action of the electrolyte, so that lithium ions are analyzed in the thinning region of the negative electrode plate close to the lower part of the battery monomer.

In view of this, the inventors have intensively studied to provide a pole piece in which an insulating layer is provided in a thinned region of the pole piece. On the one hand, the insulating layer has thickness, can reduce the volume of the clearance of the corresponding position of thinning district, and when battery monomer level or slope were placed, the electrolyte soaks the position of pole piece and risees, can alleviate the degree that the thinning district of negative pole piece lower part analyzed lithium. On the other hand, the insulating layer has an insulating effect, can form barriers to the transmission path of lithium ions, and can also relieve the lithium separation degree of the thinning area at the lower part of the negative electrode plate when the battery monomer is horizontally placed or obliquely placed.

The pole pieces mentioned in the embodiments of the present application may be positive pole pieces or negative pole pieces. The lower part of the battery cell and the upper part of the battery cell are relatively, and when the battery cell is horizontally or obliquely placed, the battery cell is close to the upper part of the battery cell in the height direction, and is close to the lower part of the battery cell.

The technical scheme described by the embodiment of the application is suitable for the battery and the electric equipment using the battery.

The electric equipment can be vehicles, mobile phones, portable equipment, notebook computers, ships, spacecrafts, electric toys, electric tools and the like. The vehicle can be a fuel oil vehicle, a fuel gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle; spacecraft including airplanes, rockets, space planes, spacecraft, and the like; the electric toy includes fixed or mobile electric toys, such as a game machine, an electric car toy, an electric ship toy, and an electric airplane toy; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railroad power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete shakers, and electric planers, among others. The embodiment of the application does not limit the electric equipment in particular.

The term "plurality" as used herein refers to more than two (including two).

For convenience of description, the following embodiments take the electric device as the vehicle 1000 as an example.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a vehicle 1000 according to some embodiments of the present application, a battery 100 is disposed in the vehicle 1000, and the battery 100 may be disposed at a bottom or a head or a tail of the vehicle 1000. The battery 100 may be used for power supply of the vehicle 1000, for example, the battery 100 may be used as an operating power source of the vehicle 1000.

The vehicle 1000 may also include a controller 300 and a motor 200, the controller 300 being configured to control the battery 100 to power the motor 200, for example, for operating power requirements during start-up, navigation, and travel of the vehicle 1000.

In some embodiments of the present application, battery 100 may not only serve as an operating power source for vehicle 1000, but may also serve as a driving power source for vehicle 1000, instead of or in part instead of fuel oil or natural gas, to provide driving power for vehicle 1000.

In some embodiments, referring to fig. 2, fig. 2 is a schematic structural diagram of a battery 100 according to some embodiments of the present application, and the battery 100 includes a plurality of battery cells 10. The plurality of battery cells 10 may be connected in series or in parallel or in series-parallel. The series-parallel connection refers to that the plurality of battery cells 10 are connected in series or in parallel.

In some embodiments, the battery 100 may further include a bus bar (not shown), through which the plurality of battery cells 10 may be electrically connected to each other, so as to realize serial connection, parallel connection, or a series-parallel connection of the plurality of battery cells 10.

The bus member may be a metal conductor such as copper, iron, aluminum, steel, aluminum alloy, or the like.

In some embodiments, the battery 100 may further include a case 20, the case 20 for accommodating the battery cell 10. The case 20 may include a first portion 201 and a second portion 202, the first portion 201 and the second portion 202 being overlapped with each other to define an accommodating space 203 for accommodating the battery cell 10. Of course, the connection between the first portion 201 and the second portion 202 may be sealed by a sealing element (not shown), which may be a sealing ring, a sealant, or the like.

The first portion 201 and the second portion 202 may have various shapes, such as a rectangular parallelepiped, a cylinder, and the like. The first portion 201 may be a hollow structure with one side opened, and the second portion 202 may be a hollow structure with one side opened, and the open side of the second portion 202 is closed to the open side of the first portion 201, so as to form the case 20 having the accommodating space 203. Of course, the first portion 201 may be a hollow structure with one side open, the second portion 202 may be a plate-like structure, and the second portion 202 may be covered on the open side of the first portion 201 to form the case 20 having the accommodation space 203.

Referring to fig. 3, fig. 3 is an exploded view of a battery cell 10 according to some embodiments of the present application, and the battery cell 10 may include a case 13, an electrode assembly 12, an end cap 11, and other functional components.

The case 13 is a member for accommodating the electrode assembly 12, and the case 13 may be a hollow structure having one end open, or the case 13 may be a hollow structure having both ends open. The material of the housing 13 may be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. The housing 13 may be of various shapes, such as a cylinder, a rectangular parallelepiped, etc. Illustratively, in fig. 3, the housing 13 is rectangular parallelepiped.

The end cap 11 is a member that covers the opening of the case 13 to isolate the internal environment of the battery cell 10 from the external environment. The end cap 11 is covered on the opening of the case 13, and the end cap 11 and the case 13 together define a sealed space for accommodating the electrode assembly 12, the electrolyte, and other functional components. The shape of the end cover 11 may be adapted to the shape of the housing 13, for example, the housing 13 is a cuboid structure, the end cover 11 is a rectangular plate structure adapted to the housing 13, for example, the housing 13 is a cylindrical structure, and the end cover 11 is a circular plate structure adapted to the housing 13. The material of the end cap 11 may be various, and the end cap 11 may be a metal material, such as copper, iron, aluminum, steel, aluminum alloy, etc. The material of the end cap 11 may be the same as or different from the material of the housing 13.

In the battery cell 10, the end caps 11 may be one or two. If the shell 13 is a hollow structure with one end forming an opening, the end cover 11 is correspondingly provided with one end; if the casing 13 has a hollow structure with openings formed at both ends, two end caps 11 are correspondingly disposed, the two end caps 11 are respectively covered on the two openings of the casing 13, one of the positive electrode tab and the negative electrode tab of the electrode assembly 12 is electrically connected with one end cap 11, and the other is electrically connected with the casing 13.

Referring to fig. 4 and 5, fig. 4 is a schematic structural diagram of an electrode assembly 12 according to some embodiments of the present application, which illustrates a state of the electrode assembly 12 inside a battery cell 10 when the battery cell 10 is horizontally placed; fig. 5 is a cross-sectional view taken along A-A of fig. 4. The electrode assembly 12 includes a positive electrode tab 121a, a negative electrode tab 121b, and a separator 122. The positive electrode tab 121a, the separator 122, and the negative electrode tab 121b form a wound structure by winding. In the wound cylindrical battery 100, the axial direction of the cylindrical battery 100 may be the width direction Y of the pole piece 121, the thinned regions 22 are located at opposite ends of the battery 100 assembly in the axial direction of the battery cell 10, and the regions of the thinned regions 22 corresponding to the separator 122 are the gaps 123.

Referring to fig. 6 and fig. 7, fig. 6 is a schematic structural diagram of a developed pole piece 121 according to some embodiments of the present application, where the pole piece 121 is developed along a length direction X; fig. 7 is a schematic view of the cross-sectional structure of fig. 6 along B-B.

The embodiment of the application provides a pole piece 121, and the pole piece 121 comprises a current collector 1, an active material layer 2 and an insulating layer 3. The active material layer 2 is provided on one side or both sides in the thickness direction Z of the current collector 1. Wherein the active material layer 2 includes a body region 21 and a thinned region 22, the thinned region 22 being located at an end of the body region 21 in the width direction Y of the current collector 1, the thinned region 22 having a thickness smaller than that of the body region 21. The insulating layer 3 covers at least a portion of the thinned region 22 in the thickness direction Z of the current collector 1.

The active material layer 2 may be provided on both sides in the thickness direction Z of the current collector 1, or the active material layer 2 may be provided only on one side in the thickness direction Z of the current collector 1.

The thinned region 22 is located at the end of the body region 21 in the width direction Y of the current collector 1, and the edge of the active material layer 2 is understandably the thinned region 22.

The body region 21 is a main region of the active material layer, and the thinned region 22 is a portion adjacent to the body region 21, and it is understood that the thinned region is a region of the active material layer along the width direction of the current collector and has a smaller thickness than the body region.

The pole piece 121 may be produced by a slitting process, in which one end of the active material layer 2 in the width direction Y of the current collector 1 may be a thinning region 22, and the like. Of course, both ends of the active material layer 2 in the width direction Y of the current collector 1 may be thinned regions 22.

The insulating layer 3 has a thickness, so that the gap 123 can be reduced, and at the same time, the insulating layer 3 has an insulating effect, so that it can form an obstacle to a transmission path of lithium ions.

When the battery cell 10 is horizontally placed or obliquely placed, the electrolyte is located at the lower part of the battery cell 10 under the action of gravity, so that the electrolyte is lack in the position corresponding to the thinning region 22 located at the upper part of the battery cell 10, lithium ions lack in the transmission path of the thinning region 22 of the negative electrode pole piece 121b embedded in the upper part of the battery cell 10, and are enriched at the lower part of the battery cell 10 under the action of the electrolyte, and lithium is separated at the position where the thinning region 22 of the negative electrode pole piece 121b located at the lower part of the battery cell 10 is located.

Therefore, in the battery cell 10 of the electrode assembly 12 formed by winding the electrode sheet 121, the insulating layer 3 is provided in the thinned region 22 of the electrode sheet 121, and on the one hand, the insulating layer 3 has a thickness, so that the gap 123 corresponding to the thinned region 22 at the upper part of the battery cell 10 can be reduced, and when the battery cell 10 is horizontally or obliquely placed, the position of the electrolyte solution infiltrating the electrode sheet 121 is raised, so that the lithium precipitation degree of the thinned region 22 of the negative electrode sheet 121b at the lower part of the battery cell 10 can be relieved. On the other hand, the insulating layer 3 has an insulating effect, which can form an obstacle to the transmission path of lithium ions, and can also relieve the lithium precipitation degree of the thinned region 22 of the negative electrode tab 121b positioned at the lower part of the battery cell 10 when the battery cell 10 is horizontally placed or obliquely placed.

In some embodiments, the insulating layer 3 completely covers the thinned region 22 to increase the barrier degree of the thinned region 22 of the negative electrode tab 121b for lithium ion transport and intercalation, and may greatly reduce the possibility of lithium precipitation in the thinned region 22 of the negative electrode tab 121b located at the lower part of the battery cell 10 when the battery cell 10 is horizontally placed or obliquely placed. Of course, in other embodiments, the insulating layer 3 may cover only a portion of the thinned region 22.

In some embodiments, the thickness of thinned region 22 decreases gradually in a direction away from body region 21. Understandably, the surface of the thinned region 22 facing away from the current collector 1 is beveled. To reduce the possibility of cracking of the active material layer 2 at both ends in the width direction Y of the pole piece 121 during winding of the pole piece 121.

In some embodiments, referring to fig. 7, the thickness of the insulating layer 3 is uniform. The thickness of the insulating layer 3 is uniform, so that the production and the manufacture of the pole piece 121 are facilitated, and the process difficulty of arranging the insulating layer 3 in the thinning area 22 of the pole piece 121 is reduced.

In some embodiments, referring to FIG. 8, FIG. 8 is another cross-sectional schematic view of FIG. 6 along line B-B. The body region 21 has a first surface 211 facing away from the current collector 1 and the insulating layer 3 has a second surface 31 facing away from the current collector 1, the first surface 211 being flush with the second surface 31, in other words the first surface 211 being coplanar with the second surface 31.

Compared with the embodiment of the insulating layer 3 with uniform thickness, in this embodiment, the first surface 211 is flush with the second surface 31, so as to improve the interface of the pole piece 121, and further reduce the gap 123 at the corresponding position of the thinning region 22, so that when the battery cell 10 is placed horizontally or obliquely, the electrolyte infiltrates into the thinning region 22 of the negative pole piece 121b at the upper part of the battery cell 10 as much as possible, so that lithium ions are conveniently inserted into the thinning region 22 of the negative pole piece 121b at the upper part of the battery cell 10, thereby reducing the enrichment of lithium ions at the lower part of the battery cell 10 and reducing the possibility of lithium precipitation in the thinning region 22 of the negative pole piece 121b at the lower part of the battery cell 10.

In some embodiments, please continue to refer to fig. 8, along the width direction Y of the current collector 1, an end of the insulating layer 3 facing away from the main body region 21 is flush with an end of the thinned region 22 facing away from the main body region 21, so as to reduce the size of the insulating layer 3 along the width direction Y of the current collector 1 and reduce the occupied area of the current collector 1.

Meanwhile, an end of the insulating layer 3 adjacent to the body region 21 may be located at the body region 21; the end of the insulating layer 3 near the main body region 21 may also be flush with the end of the thinned region 22 near the main body region 21; of course, the end of the insulating layer 3 close to the body region 21 may also be remote from the body region 21 with respect to the end of the thinned region 22 close to the body region 21.

In some embodiments, referring to fig. 9, fig. 9 is a schematic cross-sectional view of fig. 6 along A-A. Along the width direction Y of the current collector 1, one end of the insulating layer 3, which is away from the main body region 21, exceeds one end of the thinning region 22, which is away from the main body region 21, so that the insulating effect is better, the barrier of the thinning region 22, in which lithium ions are transmitted and embedded into the negative electrode tab 121b, can be increased, and the possibility of lithium precipitation in the thinning region 22 of the negative electrode tab 121b, which is positioned at the lower part of the battery cell 10, can be further reduced when the battery cell 10 is horizontally placed or obliquely placed.

In some embodiments, the insulating layer 3 is an insulating tape or an insulating coating, the insulating layer 3 has a simple structure, is convenient to obtain materials, and reduces the production difficulty of the pole piece 121.

The insulating adhesive tape can be blue adhesive, tab adhesive or adhesive tape and the like. The insulating coating may be a polyvinylidene fluoride material or a composite material including polyvinylidene fluoride, or the like.

In some embodiments, referring to fig. 8, insulation is provided along the thickness direction Z of the pole piece 121Layer 3 has a thickness H ₁ Meets the requirement that H is more than or equal to 20um ₁ ≤60um。

Illustratively, the thickness of the insulating layer 3 may be 20um, 30um, 40um, 50um, 60um, etc.

If the thickness of the insulating layer 3 is less than 20um, the thickness of the insulating layer 3 is small and the insulating effect is poor; if the thickness of the insulating layer 3 is greater than 60um, the thickness of the insulating layer 3 is too large, the insulating layer 3 and the main body region 21 form a step shape, the pole piece 121 is easy to wrinkle at the step, the interface of the pole piece 121 is affected, and potential safety hazards are caused. Therefore, the thickness of the insulating layer 3 satisfies 20 μm.ltoreq.H ₁ The insulating layer 3 has a certain thickness and good insulating effect, and meanwhile, the interface of the pole piece 121 is not affected.

In some embodiments, referring to FIG. 9, the width of the thinned region 22 along the width direction Y of the pole piece 121 is W, satisfying 0mm < W.ltoreq.14 mm.

Illustratively, the width of the thinned region 22 may be 0.3mm, 1mm, 3mm, 6mm, 10mm, 12mm, 14mm, etc.

If the width of the thinned region 22 is equal to 0, the thinned region 22 does not exist, and the possibility of cracking of the active material layer 2 at the edge of the pole piece 121 during the winding of the pole piece 121 by the thinned region 22 cannot be raised. If the size of the current collector 1 in the width direction Y is certain, if the thinned area 22 is greater than 14mm, the thinned area 22 occupies an excessively large coating area of the current collector 1, which affects the energy density of the battery cell 10; therefore, W is more than 0mm and less than or equal to 14mm, the active material layer 2 at the edge of the pole piece 121 is not easy to crack in the winding process of the pole piece 121, and meanwhile, the battery cell 10 has higher energy density.

In some embodiments, the pole piece 121 is a negative pole piece 121b, and the insulating layer 3 is directly disposed on the thinned region 22 of the negative pole piece 121 b. When the battery cell 10 using the negative electrode tab 121b is placed horizontally or obliquely, lithium ions cannot be inserted into the thinning region 22 of the negative electrode tab 121b near the lower part of the battery cell 10, and lithium precipitation in the thinning region 22 of the negative electrode tab 121b can be relieved to a greater extent.

In other embodiments, the electrode sheet 121 may be a positive electrode sheet 121a, and the insulating layer 3 is disposed in the thinned region 22 of the positive electrode sheet 121a to reduce the gap 123 at the corresponding position of the thinned region 22. When the battery cell 10 of the positive electrode plate 121a is horizontally placed or obliquely placed, electrolyte infiltrates into the thinning region 22 of the negative electrode plate 121b close to the upper part of the battery cell 10, a transmission path is provided for the thinning region 22 of the negative electrode plate 121b of the lithium ion embedded battery cell 10, and the enrichment of lithium ions in the lower part of the battery cell 10 is reduced, so that lithium precipitation of the thinning region 22 of the negative electrode plate 121b is relieved.

In some embodiments, the present application provides a negative electrode tab 121b, the negative electrode tab 121b including a current collector 1, an active material layer 2, and an insulating layer 3. The active material layers 2 are provided on both sides in the thickness direction Z of the current collector 1. Wherein the active material layer 2 includes a body region 21 and a thinned region 22, the thinned region 22 being located at an end of the body region 21 in the width direction Y of the current collector 1, the thinned region 22 having a thickness smaller than that of the body region 21. The insulating layer 3 covers the thinned region 22 in the thickness direction Z of the current collector 1, the insulating layer 3.

In some embodiments, referring to fig. 4 and 5, the present application provides an electrode assembly 12, where the electrode assembly 12 includes a positive electrode tab 121a, a negative electrode tab 121b, a separator 122, and an insulating layer 3. The negative electrode tab 121b, the separator 122 and the separator 122 are wound to form a wound structure, the negative electrode tab 121b includes a current collector 1 and an active material layer 2 disposed on at least one side of the current collector 1 in a thickness direction Z, the active material layer 2 includes a body region 21 and a thinning region 22, and the thinning region 22 is located at an end of the body region 21 in a width direction Y of the current collector 1. The insulating layer 3 covers at least a part of the thinned region 22 in the thickness direction Z of the current collector 1.

In some embodiments, the positive electrode tab 121a includes a current collector 1 and an active material layer 2 disposed on at least one side in a thickness direction Z of the current collector 1, and the active material layer 2 includes a body region 21 and a thinned region 22 along a width direction Y of the current collector 1, the thinned region 22 being located at an end of the body region 21 along the width direction Y of the current collector 1. The insulating layer 3 covers at least a part of the thinned region 22 in the thickness direction Z of the current collector 1.

The embodiment of the present application also provides a battery cell 10, since the battery cell 10 includes the electrode assembly 12 in any one of the embodiments, when the battery cell 10 is placed horizontally or obliquely, the possibility of lithium precipitation in the thinned region 22 of the negative electrode tab 121b can be reduced.

The embodiment also provides a battery 100, which comprises the battery cell 10 in the embodiment. Since the battery 100 includes the battery cell 10 according to any one of the above embodiments, the battery 100 has the technical effects of the battery cell 10 described above, and will not be described herein.

The embodiment of the application also provides an electric device, which comprises the battery 100 in the embodiment.

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other.

The above embodiments are only for illustrating the technical solution of the present application, and are not intended to limit the present application, and various modifications and changes may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims (15)

1. A pole piece, comprising:

a current collector;

the active material layer is arranged on one side or two sides of the thickness direction of the current collector, the active material layer comprises a main body region and a thinning region, the thinning region is positioned at the end part of the main body region along the width direction of the current collector, and the thickness of the thinning region is smaller than that of the main body region;

and an insulating layer covering at least a portion of the thinned region in a thickness direction of the current collector.

2. The pole piece of claim 1, wherein the insulating layer completely covers the thinned region.

3. A pole piece according to claim 1, characterized in that the thickness of the thinned area decreases gradually in a direction away from the body area.

4. The pole piece of claim 1, wherein the insulating layer is of uniform thickness.

5. A pole piece according to claim 1 or 2, characterized in that the body region has a first surface facing away from the current collector, the insulating layer has a second surface facing away from the current collector, the first surface being flush with the second surface.

6. The pole piece of claim 1, wherein an end of the insulating layer facing away from the body region is flush with an end of the thinned region facing away from the body region in a width direction of the current collector.

7. The pole piece of claim 1, wherein an end of the insulating layer facing away from the body region exceeds an end of the thinned region facing away from the body region in a width direction of the current collector.

8. The pole piece of claim 1, wherein the insulating layer is an insulating tape or an insulating coating.

9. The pole piece of claim 1, wherein the thickness of the insulating layer in the thickness direction of the pole piece is H ₁ Meets the requirement that H is more than or equal to 20um ₁ ≤60um。

10. The pole piece of claim 1, wherein the width of the thinned region is W, along the width direction of the pole piece, satisfying 0mm < w.ltoreq.14 mm.

11. The pole piece of claim 1, wherein the pole piece is a negative pole piece.

12. An electrode assembly comprising a pole piece according to any one of claims 1 to 11.

13. A battery cell comprising the electrode assembly of claim 12.

14. A battery comprising the battery cell of claim 13.

15. A powered device comprising the battery of claim 14, the battery configured to power the powered device.

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