CN216563204U - Pole piece and battery - Google Patents

Abstract

The utility model provides a pole piece and a battery, wherein the pole piece comprises a current collector and active layers positioned on two opposite surfaces of the current collector, the current collector comprises a first area and second areas positioned on two sides of the first area, the active layers comprise a first part corresponding to the first area and a second part corresponding to the second area, the thickness of the second part is smaller than that of the first part, and the active layers further comprise a conductive layer positioned between the second part and the current collector. The conducting layer has a certain thickness, so that the height of the second part can be increased, the difference of the thickness between the coating in the second area and the coating in the first area is reduced, the problem of non-uniform interface of the battery cell is solved, the distance between the anode and the cathode at the edge of the battery cell is shortened, the path of ions is also shortened, the diffusion speed of the ions between the anode and the cathode is accelerated, the energy density of the battery is increased, and the capacity of the battery is improved.

Description

Pole piece and battery

Technical Field

The utility model relates to the technical field of battery structures, in particular to a pole piece and a battery.

Background

A lithium ion battery is a type of secondary battery that mainly operates by movement of lithium ions between a positive electrode and a negative electrode. In the process of charging and discharging, lithium ions are inserted and extracted back and forth between the two electrodes; during charging, lithium ions are extracted from the positive electrode and are inserted into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge. The lithium ion battery has the advantages of high energy density, high voltage platform, small volume, long service life, no memory effect, low self-discharge rate, environmental friendliness and the like, and is widely applied to the electronic terminal industry, the new energy industry, the energy storage industry and the like.

The lithium ion battery generally comprises a shell and an electric core, wherein the electric core is positioned in the shell, the shell is filled with electrolyte, the electric core comprises a positive pole piece, a diaphragm and a negative pole piece, the positive pole piece and the negative pole piece respectively comprise a current collector and active layers coated on two opposite surfaces of the current collector, a positive active material layer is coated on the positive pole piece, a negative active material layer is coated on the negative pole piece, and the active layers are used for generating chemical reaction in the electrolyte to generate electric energy. And a diaphragm is arranged between the positive pole piece and the negative pole piece, and the three can form a laminated battery cell after being laminated, or the three can be wound to form a winding battery cell after being laminated.

However, due to the coating process of the active layer, the active layer includes a coating region and thinning regions located at two sides of the coating region, and the thickness of the thinning region is thinner than that of the coating region, so that when a formed battery cell is formed, the problem of poor interface (different from the thickness of the middle part) exists at the top and the bottom of the battery cell, which causes the ionic distance path at the edge of the positive and negative electrode plates to be too long, and the battery capacity is affected.

SUMMERY OF THE UTILITY MODEL

The utility model provides a pole piece and a battery, which are used for solving the problems that the distance path of edge ions of positive and negative pole pieces is longer and the battery capacity is influenced because the top and the bottom of the conventional battery core have poor interfaces.

A first aspect of the present application provides a pole piece, comprising: the current collector and the active layers are respectively positioned on two opposite surfaces of the current collector;

the current collector comprises a first region and second regions positioned on two sides of the first region, the active layer comprises a first part and a second part, the first part corresponds to the first region, the second part corresponds to the second region, and the thickness of the second part is smaller than that of the first part;

further comprising a conductive layer between the second portion and the current collector.

Through increasing the conducting layer between second portion and the mass flow body, the conducting layer can not influence ionic conductivity, and the conducting layer has certain thickness, can improve the height of second portion (the distance between second portion and the mass flow body), also can improve the thickness of active layer in the second district, reduce the difference of thickness between the coating in the second district and the coating in the first district, after forming electric core, the problem that the interface that electric core exists differs has been improved, the distance of electric core edge positive negative pole has been shortened, also the route of ion has been shortened, the diffusion velocity of ion between positive negative pole has been accelerated, thereby the energy density of battery has been improved, the capacity of battery has been promoted.

And the moving path of the ions is shortened, the diffusion speed of the ions between the positive electrode and the negative electrode is accelerated, the phenomenon of lithium precipitation at the edge is reduced or avoided, and the safety of the battery is improved. Meanwhile, the thickness of the conducting layer can be controlled, so that the thickness of the coating in the second area of the edge can be controlled, the density of the edge surface of the pole piece can be controlled, and the energy density of the battery can be further improved.

In one possible implementation, a ratio of a sum of thicknesses of the conductive layer and the second portion to a thickness of the first portion is equal to or greater than 0.8.

In one possible implementation, the sum of the thicknesses of the conductive layer and the second portion is equal to the thickness of the first portion.

In a possible implementation manner, the current collector further includes an insulating layer, the insulating layer is located on the current collector, the insulating layer is located on a side, facing away from the first area, of the second area, and a part of the insulating layer overlaps with the conductive layer and the second portion.

In a possible implementation manner, the pole piece further comprises a plurality of pole lugs, the pole lugs are distributed along the length direction of the pole piece, and part of the insulation layer is located on the pole lugs.

In a possible implementation manner, a side surface of the conductive layer facing away from the first portion is disposed at an acute angle with respect to the current collector.

In one possible implementation, the conductive layer includes an adhesive layer and an electrical conductor within the adhesive layer;

the electric conductor is a nonmetal electric conductor which at least comprises a carbon electric conductor.

In one possible implementation, the ratio of the thickness of the second portion to the thickness of the first portion is 0.1-0.9;

and/or the ratio of the thickness of the conducting layer to the thickness of the first part is 0.1-0.9.

In one possible implementation, a ratio of a thickness of the insulating layer to a thickness of the first portion is less than 0.8.

In a possible implementation manner, the width of the overlapping area of the insulating layer, the conductive layer and the second part is less than 2 mm.

A second aspect of the present application provides a battery, including a casing and a battery cell disposed in the casing, where the battery cell includes a positive electrode plate, a diaphragm, and a negative electrode plate, and the diaphragm is located between the positive electrode plate and the negative electrode plate;

at least one of the positive pole piece and the negative pole piece is any one of the pole pieces.

The positive pole piece and/or the negative pole piece in the battery cell are/is the pole pieces, and the pole pieces are provided with the conducting layers between the active layer and the current collector in the second area, so that the difference of the thickness between the coating in the second area and the coating in the first area is reduced, the problem of different interfaces in the battery cell is solved, the path of ions is shortened, the diffusion speed of the ions between the positive pole and the negative pole is accelerated, and the capacity of the battery is improved. But also helps to reduce or avoid the phenomenon of lithium precipitation at the edge and improves the safety of the battery.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a winding schematic diagram of a winding type battery cell provided in an embodiment of the present application;

fig. 2 is a schematic structural diagram of a laminated battery cell provided in an embodiment of the present application;

fig. 3 is a schematic top view of a pole piece according to an embodiment of the present disclosure;

FIG. 4 is a schematic cross-sectional view along AA in FIG. 3;

fig. 5 is a schematic cross-sectional dimension diagram of a pole piece according to an embodiment of the present application.

Description of reference numerals:

100-electric core;

10-positive pole piece;

11-a current collector;

11 a-a first zone;

11 b-a second zone;

12-an active layer;

121-a first portion;

122-a second portion;

13-a conductive layer;

14-an insulating layer;

15-positive pole tab;

20-a negative pole piece;

21-a negative electrode tab;

30-a membrane.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

With the development of times, people have continuously improved the demand for energy storage. The lithium ion battery gradually occupies the market in the fields of consumer electronics, electric vehicles, automobiles, electric tools, smart power grids and the like due to a series of advantages of high energy density, high single battery working voltage, large working temperature range, low self-discharge, long cycle life and the like, and has wide application prospect.

Fig. 1 is a winding schematic diagram of a winding type battery cell provided in an embodiment of the present application, and fig. 2 is a structural schematic diagram of a laminated battery cell provided in the embodiment of the present application.

The application provides a pole piece and battery, wherein, the battery includes the casing and sets up the electric core in the casing, and electric core is specific including the pole piece, and the electric core is including positive pole piece, diaphragm and negative pole piece, and the diaphragm is located between positive pole piece and the negative pole piece. The positive pole piece can extend out of a positive pole lug, and the negative pole piece can extend out of a negative pole lug.

The positive electrode tab and the negative electrode tab can be formed by cutting the coated current collector, and the number of the positive electrode tabs and the number of the negative electrode tabs of the battery cell can be multiple.

The battery may be a wound battery, that is, the battery cell in the battery may be a battery cell in a wound structure. Alternatively, the battery may be a laminated battery, that is, the battery cell in the battery may be a battery cell in a laminated structure.

Referring to fig. 1, the battery cell 100 of the battery may be a winding-type battery cell, that is, after the positive electrode plate 10, the separator 30 and the negative electrode plate 20 are sequentially stacked, the positive electrode plate 10, the separator 30 and the negative electrode plate 20 are wound together along one direction, and finally, the battery cell 100 is in a winding structure.

Alternatively, referring to fig. 2, the battery cell 100 of the battery may be a cell in a laminated structure, that is, the positive electrode plate 10, the separator 30, and the negative electrode plate 20 are sequentially stacked, so that the battery cell 100 is formed in a laminated shape in fig. 2.

The positive electrode plate 10 is composed of a current collector and positive active material layers coated on two sides of the current collector, the positive active material may be lithium cobaltate, lithium iron phosphate, lithium manganate, lithium nickel manganate, etc., and in some examples, the positive active material may also be other high-potential materials, etc.

The negative electrode sheet 20 may be composed of a current collector and a negative active material layer coated on two sides of the current collector, and the negative active material may be graphite, silicon, carbon, or other materials with low potential.

Both the winding type battery core and the laminated type battery core are formed after formation, and because in a common battery processing technology, when an active material is coated, thinning areas are formed on the edges of two sides of a pole piece, and the thickness of the active material layer in the thinning areas is smaller than that of the active material layer in the other areas. For example, taking a positive electrode plate as an example, two side edges of the current collector have thinned regions, and the thickness of the positive electrode active material layer in the thinned regions is smaller. Like this become electric core after, edge thickness differs with other regional thickness, and the positive pole piece and diaphragm, the laminating range upon range of that the negative pole piece just can not be fine at electric core top and bottom edge are laminated, make the top or the bottom of electric core have the problem that the interface differs usually, lead to electric core edge ion to be apart from the route longer, so not only can reduce the energy density of battery, influence battery capacity, but also take place to analyse lithium easily, have the problem of potential safety hazard.

Based on this, the pole piece and the battery provided by the embodiment of the application can shorten the ion path, and the top and bottom interfaces of the battery are well formed in the formation process, so that the diffusion speed of ions is accelerated, the battery capacity is improved, and the problem of lithium precipitation can be improved.

Fig. 3 is a schematic top view structure diagram of a pole piece according to an embodiment of the present disclosure, fig. 4 is a schematic cross-sectional structure diagram along an AA plane in fig. 3, and fig. 5 is a schematic cross-sectional dimension diagram of a pole piece according to an embodiment of the present disclosure.

It should be noted that fig. 3 to 5 are schematic structural diagrams of the pole piece before the pole piece is formed without cutting.

Referring to fig. 3 and 4, the pole piece includes a current collector and active layers on opposite sides of the current collector, respectively. In the embodiment of the present application, the positive electrode tab is used as the positive electrode tab 10, and the active layer 12 is disposed on the current collector 11. The current collector 11 may be a substrate made of copper foil, or the current collector 11 may be a substrate made of another conductive metal material. The thickness of current collector 11 may be 6 μm to 20 μm.

The active layer 12 of the positive electrode sheet may be a coating layer formed of a composite material containing a combination of a positive electrode active material, a binder, and a conductive agent. The battery is a lithium ion battery, and the positive active material can be one or a combination of more of lithium cobaltate, lithium iron phosphate, lithium manganate and lithium nickel manganate.

The adhesive can be made of one or more of polyvinylidene fluoride, sodium carboxymethylcellulose, lithium hydroxycellulose, styrene-butadiene rubber, polyacrylic acid, a homopolymer or copolymer of tetrafluoroethylene and hexafluoropropylene, and polyvinyl alcohol. The material of the conductive agent may be a carbon material.

Among them, the active layer 12 may be a coating layer formed on the opposite sides of the current collector 11 by spraying, sputtering, deposition, or the like. The specific formation manner of the active layer 12 on the current collector 11 is not limited in the embodiments of the present application.

As shown in fig. 4, the current collector 11 may include a first region 11a and a second region 11b, that is, the current collector 11 may be divided into the second region 11b and the first region 11a, wherein the second region 11b is located on both sides of the first region 11 a.

The active layer 12 may include a first portion 121 and a second portion 122, the first portion 121 corresponds to the first region 11a, the second portion 122 corresponds to the second region 11b, that is, the active layer 12 in the first region 11a is the first portion 121, the active layer 12 in the second region 11b is the second portion 122, and the thickness of the second portion 122 is smaller than that of the first portion 121, so as to meet the process requirement of coating the active layer 12.

With continued reference to fig. 4, the electrode sheet further includes a conductive layer 13, the conductive layer 13 is located between the second portion 122 and the current collector 11, that is, the conductive layer 13 is located between the active layer in the second region 11b and the current collector 11, the conductive layer 13 does not affect the conductivity of ions, and the conductive layer 13 has a certain thickness, which can increase the height of the second portion 122 (the distance between the second portion 122 and the current collector 11). That is, the height of the active layer in the second region 11b can be increased, and the difference in thickness between the coating layer in the second region 11b and the coating layer in the first region 11a can be reduced. After the battery cell 100 is formed, the problem of non-uniform interfaces of the battery cell 100 is solved, the distances between the positive electrode and the negative electrode on the two sides of the edge of the battery cell 100 are shortened, namely, the path of ions is shortened, and the diffusion speed of the ions between the positive electrode and the negative electrode is accelerated, so that the energy density of the battery is improved, and the capacity of the battery is improved.

And the moving path of the ions is shortened, the diffusion speed of the ions between the positive electrode and the negative electrode is accelerated, the phenomenon of lithium precipitation at the edge is reduced or avoided, and the safety of the battery is improved. Meanwhile, the thickness of the conductive layer 13 can be controlled (for example, the thickness can be controlled by adjusting the material and the coating process), so that the thickness of the coating in the second region 11b of the edge can be controlled, that is, the density of the edge surface of the pole piece can be controlled, and the further improvement of the energy density of the battery is facilitated.

The conductive layer 13 may include an adhesive layer (not shown in the figure) and a conductor (not shown in the figure) located in the adhesive layer, specifically, the conductor may be a non-metal conductor, for example, the conductor may be a carbon conductor, and has a good conductivity, so as to ensure that the conductive layer 13 does not affect the conductivity of ions.

The carbon conductor may be in the form of a dot, a tube, a branched chain, or the like. The particle size of the carbon conductor may be 100nm to 20 μm.

The adhesive layer can fix the conductive layer 13 on the current collector 11 well, so that the conductive layer 13 is convenient to form and fix.

The adhesive layer may be a film layer formed of an adhesive. The molding material of the adhesive can comprise at least one of polyvinylidene fluoride, sodium carboxymethylcellulose, lithium hydroxycellulose, styrene-butadiene rubber, polyacrylic acid, a homopolymer or copolymer of tetrafluoroethylene and hexafluoropropylene, and polyvinyl alcohol.

The conductive layer 13 may be formed by coating a composite including a binder and an electric conductor on the current collector 11 by spraying, sputtering, deposition, or the like.

As shown in fig. 3 and 4, the pole piece further includes an insulating layer 14, where the insulating layer 14 is disposed on the current collector 11, and specifically, the insulating layer 14 is located on the side of the second region 11b of the current collector 11 facing away from the first region 11a, that is, the insulating layer 14 is located on the outer side of the second portion 122 and the conductive layer 13 (the side facing away from the first portion 121), so that the insulating layer 14 is located on both sides of the active layer 12. In the processing procedures of cutting the electrode lug and the like, the current collector 11 may be a sharp hard structure which generates burrs, drawn wires and the like, the insulating layers 14 positioned on the two sides of the active layer 12 can play a role in wrapping the generated burrs and drawn wires and the like, the burrs, drawn wires and the like generated in the production process can be prevented from piercing the diaphragm 30 between the positive electrode piece 10 and the negative electrode piece 20, and the safety of the battery is further improved.

The pole piece 10 may have a plurality of tabs, for example, a plurality of tabs may be formed by cutting one edge of the pole piece 10 shown in fig. 3, and the plurality of tabs may be distributed at intervals along the length direction of the pole piece 10. When cutting out and forming the pole lug, the insulating layer 14 of the part can be positioned on the pole lug, so that the insulating layer 14 can effectively play a role in wrapping burrs, drawn wires and the like generated in the cutting process, and the safety of the battery is further improved.

The width of the insulating layer 14 on the tab can be 0.1mm-1 mm. Ensuring that the insulating layer 14 is able to encapsulate the hard-tipped structures created during the cutting of the ears.

In this case, a part of the insulating layer 14 may overlap the conductive layer 13 and the second portion 122, that is, a part of the insulating layer 14 covers the conductive layer 13 and the second portion 122 (see fig. 5), so as to form an overlapping area 16 shown in fig. 5, and the projected portions of the insulating layer 14, the conductive layer 13, and the second portion 122 on the current collector 11 are overlapped, in other words, the insulating layer 14 is partially miscible with the conductive layer 13 and the edge of the active layer in the second region 11 b.

Specifically, the width of the overlapping region 16 is the width of the region where the projections of the insulating layer 14, the conductive layer 13 and the second portion 122 on the current collector 11 overlap, and the width may be less than 2mm, which may facilitate the coating of the insulating layer 14. Note that the width direction is parallel to a direction from the active layer 12 to the insulating layer 14, that is, a direction in which the insulating layer 14 and the active layer 12 are stacked, such as the x direction in fig. 3. The thickness direction means a direction parallel to a direction from the current collector 11 toward the active layer 12, that is, a direction in which the active layer 12 is laminated with the current collector 11, such as the y direction in fig. 4.

The insulating layer 14 may be a coating layer formed by spraying, sputtering, depositing, or the like on the current collector 11.

The insulating layer 14, the conductive layer 13, and the active layer 12 may be formed by wet spraying, and for the conductive layer 13, a compound including a binder and a conductor may be added with a solvent to form a liquid, and then sprayed on the current collector 11 by a spraying device, so as to form the conductive layer 13. Thus, as shown in fig. 4, the side of the conductive layer 13 facing away from the first portion 121 forms an acute angle with the current collector 11, which is convenient for spraying. In the spraying operation, the conductive layer 13, the active layer 12 and the insulating layer 14 are sequentially formed on the current collector 11 by spraying, and the conductive layer 13 is formed to reduce the difference in thickness between the coating in the second region 11b and the coating in the first region 11a, thereby avoiding the complication of the process for increasing the conductive layer 13 and ensuring the production efficiency.

In addition, the coating arrangement of the conductive layer 13, the insulating layer 14 and the active layer 12 is realized through wet spraying, so that the conductive layer 13, the insulating layer 14 and the active layer 12 have good adhesion rate and high compressive strength, and the performance of the pole piece 10 is improved. And the spraying method is simple, convenient to operate, beneficial to improving the working environment and improving the working efficiency.

Note that, an included angle is also formed between the side surface of the conductive layer 13 facing the first portion 121 and the current collector 11, and the included angle is also an acute angle. Accordingly, when the spraying of the insulating layer 14 is implemented by using wet spraying, an acute angle may also be formed between the side of the insulating layer 14 facing away from the first portion 121 and the current collector 11, and an acute angle may also be formed between the side of the second portion 122 of the active layer 12 facing away from the first portion 121 and the side of the conductive layer 13 facing away from the current collector 11.

The ratio of the sum of the thicknesses of the conductive layer 13 and the second portion 122 to the thickness of the first portion 121 may be greater than 0.8, and in particular, referring to fig. 5, (d1+ d2)/d3 > 0.8 if the average thickness of the conductive layer 13 is d1, the average thickness of the second portion 122 is d2, and the average thickness of the first portion 121 is d 3. Thus, the difference in thickness between the coating in the second region 11b and the coating in the first region 11a is further ensured to be reduced, the distance between the positive electrode and the negative electrode at the edge of the battery cell 100 is shortened, the energy density of the battery is further improved, and the problem of lithium precipitation is solved.

In a possible embodiment, the sum of the thicknesses of the conductive layer 13 and the second portion 122 may be equal to the thickness of the first portion 121, that is, (d1+ d2)/d3 is 1, that is, the protrusion thickness in the second region 11b and the coating thickness in the first region 11a can be kept consistent, so that the distance between the positive electrode and the negative electrode is shortened as much as possible, the problem of inconsistent interface sizes at the edge of the battery cell 100 is avoided, and the capacity of the battery is effectively improved. Meanwhile, the problem of lithium precipitation is remarkably improved, and the safety of the battery is further improved.

Specifically, the thickness of the first portion 121 may be 30 μm to 200 μm, that is, the thickness d3 of the active layer located in the first region 11a may range from 30 μm to 200 μm, which may ensure that the battery has better energy.

The ratio of the thickness of the second portion 122 to the thickness of the first portion 121 is 0.1-0.9, i.e., d2 and d3 satisfy: d2/d3 of 0.1 is not less than 0.9, so that the coating process of the active layer 12 can be satisfied, and the forming of the active layer 12 is facilitated.

The ratio of the thickness of the conductive layer 13 to the thickness of the first portion 121 is 0.1-0.9, i.e. d1 and d3 satisfy: 0.1 d1/d3 0.9, which facilitates the sum of the thicknesses of the conductive layer 13 and the second portion 122 being equal to the sum of the thicknesses of the first portion 121, thereby enabling an improvement in the difference in thickness between the coating in the second region 11b and the coating in the first region 11 a.

With continued reference to fig. 5, the ratio of the thickness of the insulating layer 14 to the thickness of the first portion 121 may be less than 0.8, i.e., the ratio of the average thickness d4 of the insulating layer 14 to the thickness d3 of the first portion 121 is less than 0.8. Therefore, the insulating layer 14 can play a good role in preventing the current collector 11 from generating burrs, wire drawing and the like to pierce the diaphragm 30, and meanwhile, the influence of the excessively thick insulating layer 14 on the electrical performance of the pole piece can be avoided.

The width of the insulating layer 14 can be 1mm-3mm, so that the insulating layer 14 can play a good role in preventing the diaphragm 30 from being pierced, and meanwhile, the influence of excessive insulating layers 14 on the electrical performance of the pole piece can be avoided.

In the embodiment of the present application, the width of the active layer 12 may be 50mm to 500mm, so as to ensure that the battery has a good capacity. The width of the second region 11b may be less than 10mm, and in particular, the width of the second region 11b may be 3mm to 10 mm. The width of the conductive layer 13 should be less than 10mm to ensure that the conductive layer 13 can be disposed between the active layer 12 and the current collector 11 in the second region 11b to reduce the difference between the coating in the second region 11b and the coating in the first region 11 a.

In this embodiment, it should be noted that the battery cell includes a positive electrode plate and a negative electrode plate, where the positive electrode plate may be the above-mentioned electrode plate, that is, a current collector of the positive electrode plate includes a second region, and the above-mentioned conductive layer is provided between the positive active layer and the current collector in the second region.

Alternatively, the negative electrode plate of the battery cell may be the above-mentioned electrode plate, that is, the current collector of the negative electrode plate includes a second region, and the above-mentioned conductive layer is provided between the negative active layer and the current collector in the second region.

Or, the positive pole piece and the negative pole piece of the battery cell can be both the pole pieces, so that the capacity of the battery is further remarkably improved.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, merely for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the utility model.

In the description of the present invention, it is to be understood that the terms "comprises" and "comprising," and any variations thereof, as used herein, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integral to one another; either directly or indirectly through intervening media, may be internal to the two elements or may be in interactive relationship with the two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the utility model has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (11)

1. A pole piece, comprising: the current collector and the active layers are respectively positioned on two opposite surfaces of the current collector;

the current collector includes a first region and second regions located at both sides of the first region, the active layer includes a first portion and a second portion, the first portion corresponds to the first region, the second portion corresponds to the second region, and a thickness of the second portion is less than a thickness of the first portion;

further comprising a conductive layer between the second portion and the current collector.

2. The pole piece of claim 1 wherein a ratio of a sum of thicknesses of the conductive layer and the second portion to a thickness of the first portion is 0.8 or greater.

3. The pole piece of claim 1, wherein a sum of the thicknesses of the conductive layer and the second portion is equal to a thickness of the first portion.

4. The pole piece of any one of claims 1 to 3, further comprising an insulating layer, wherein the insulating layer is located on the current collector, the insulating layer is located on a side of the second region facing away from the first region, and a portion of the insulating layer overlaps the conductive layer and the second portion.

5. The pole piece of claim 4, further comprising a plurality of tabs distributed along a length of the pole piece, wherein a portion of the insulation layer is disposed on the tabs.

6. The pole piece of claim 4, wherein a side of the conductive layer facing away from the first portion is disposed at an acute angle with respect to the current collector.

7. The pole piece of any one of claims 1 to 3, wherein the conductive layer comprises an adhesive layer and a conductor disposed within the adhesive layer;

the electric conductor is a nonmetal electric conductor which at least comprises a carbon electric conductor.

8. The pole piece of any one of claims 1 to 3, wherein the ratio of the thickness of the second portion to the thickness of the first portion is from 0.1 to 0.9;

and/or the ratio of the thickness of the conducting layer to the thickness of the first part is 0.1-0.9.

9. The pole piece of claim 4 wherein the ratio of the thickness of the insulating layer to the thickness of the first portion is less than 0.8.

10. The pole piece of claim 4, wherein the width of the overlapping area of the insulating layer and the conductive layer and the second portion is less than 2 mm.

11. The battery is characterized by comprising a shell and a battery cell arranged in the shell, wherein the battery cell comprises a positive pole piece, a diaphragm and a negative pole piece, and the diaphragm is positioned between the positive pole piece and the negative pole piece;

at least one of the positive pole piece and the negative pole piece is the pole piece of any one of the claims 1 to 10.

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