Battery cell and battery

Abstract

The utility model discloses an electric core and a battery, which comprise an electrode assembly formed by winding a negative plate, a diaphragm and a positive plate together, the electrode assembly comprises a plane area and corner areas positioned on two sides of the plane area, at least one corner area is internally provided with a pore layer for storing electrolyte, and the pore layer is positioned between the negative plate and the positive plate. According to the technical scheme provided by the utility model, the conditions of lithium precipitation in a corner area of the battery cell and deterioration of a pole piece interface are improved, and the cycle performance of the battery cell is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and particularly relates to a battery cell and a battery. Background Art

[0002] Nowadays, various countries are vigorously developing green and efficient secondary batteries. As a new type of secondary battery, lithium-ion batteries have the advantages of large energy density and power density, high working voltage, light weight, small volume, long cycle life, good safety, and environmental friendliness, and have broad application prospects in portable electrical appliances, electric tools, large-scale energy storage, and electric vehicle power sources.

[0003] At present, the batteries of consumer electronic products mostly use battery cells with a wound structure. The middle area of this type of battery cell is a flat area, and both sides are corner areas (i.e., arc-shaped bending areas). During the cycle, the anode sheet (i.e., the negative electrode sheet) of the battery cell will gradually expand due to the insertion of lithium ions. However, due to the mutual restraint between the electrode sheets in the corner area of the battery cell, the expanded anode sheet will continuously squeeze the adjacent separator and the cathode sheet (i.e., the positive electrode sheet), resulting in stress concentration in the local area of the corner area, the negative electrode sheet sticking to the positive electrode sheet, and the electrolyte between the negative electrode sheet and the positive electrode sheet being gradually squeezed out, thereby causing lithium deposition at the electrode interface in this area and deteriorating the cycle performance of the battery cell. Summary of the Utility Model

[0004] The utility model provides a battery cell, aiming to improve the lithium deposition in the corner area of the battery cell and the deterioration of the electrode interface, and enhance the cycle performance of the battery cell.

[0005] To achieve the above object, a battery cell proposed by the utility model includes an electrode assembly formed by winding a negative electrode sheet, a separator, and a positive electrode sheet together. The electrode assembly includes a flat area and corner areas located on both sides of the flat area. At least one of the corner areas is provided with a pore layer for accumulating electrolyte, and the pore layer is located between the negative electrode sheet and the positive electrode sheet.

[0006] In some embodiments, the pore layers are provided in both of the corner areas.

[0007] In some embodiments, at least one of the pore layers is provided on the negative electrode sheet in the corner area; and / or,

[0008] at least one of the pore layers is provided on the positive electrode sheet in the corner area; and / or,

[0009] at least one of the pore layers is provided on the separator in the corner area.

[0010] In some embodiments, there is a pore layer between each adjacent positive and negative electrode sheets in the corner area; and / or,

[0011] The pore layer is provided on each layer of the negative electrode sheet in the corner area; and / or,

[0012] The pore layer is provided on each layer of the positive electrode sheet in the corner area.

[0013] In some embodiments, the pore layer on the negative electrode sheet is located on one or both sides of the negative electrode sheet; and / or,

[0014] The pore layer on the positive electrode sheet is located on any one or both sides of the positive electrode sheet; and / or,

[0015] The pore layer on the separator is located on any one or both sides of the separator.

[0016] In some embodiments, in the same corner area, a plurality of the pore layers are provided between at least one layer of the negative electrode sheet and an adjacent layer of the positive electrode sheet, and the plurality of pore layers are distributed at intervals along the negative electrode sheet.

[0017] In some embodiments, the pore layer is an electrospun membrane.

[0018] In some embodiments, the material of the electrospun membrane is any one or any combination of polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, and polyimide.

[0019] In some embodiments, the thickness of the pore layer is 2 to 20 micrometers; and / or,

[0020] The porosity of the pore layer is 40% to 80%; and / or,

[0021] The width of the pore layer is 30% to 100% of the arc length of the adjacent electrode sheet in the current corner area; and / or,

[0022] The length of the pore layer is greater than or equal to the width of the positive electrode sheet and less than or equal to the width of the separator.

[0023] The present utility model further provides a battery, including a housing and the above - mentioned battery cell, and the battery cell is installed in the housing.

[0024] The technical solution of the electric core of the present utility model is to arrange a pore layer for accumulating electrolyte between the positive and negative electrode sheets in the corner area of the electrode assembly, so that the negative electrode sheet and the positive electrode sheet in the corner area are always separated by the pore layer, ensuring the gap size between the negative electrode sheet and the positive electrode sheet. Even if the negative electrode sheet expands due to the insertion of lithium ions, the situation that the negative electrode sheet squeezes out all the electrolyte between it and the positive electrode sheet will not occur. Moreover, the pore layer is a three-dimensional grid structure with a high porosity, which can store the electrolyte between the positive and negative electrode sheets inside it, thereby ensuring sufficient electrolyte between the positive and negative electrode sheets, enabling the negative electrode sheet and the positive electrode sheet in the corner area to work normally, effectively improving the situation of the deterioration of the electrode interface and lithium deposition caused by the lack of electrolyte in the corner area, and further effectively improving the cycle performance of the electric core. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the electrode assembly of the electric core in an embodiment of the present utility model;

[0026] Figure 2 is Figure 1 A longitudinal sectional view of the corner area of the electrode assembly in the embodiment;

[0027] Figure 3 It is a longitudinal sectional view of the corner area of the electrode assembly in another embodiment of the present utility model.

[0028] Explanation of the reference numerals in the drawings: 10 - negative electrode sheet, 20 - separator, 30 - positive electrode sheet, 40 - pore layer, Q1 - flat area, Q2 - corner area. Detailed Embodiment

[0029] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.

[0030] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present utility model are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0031] It should also be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0032] In addition, the descriptions involving "first", "second", etc. in the present utility model are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.

[0033] The present utility model provides an electric core, which can be used to manufacture batteries for various electronic products, such as mobile phone batteries, tablet computer batteries, etc.

[0034] Referring to Figure 1 and Figure 2 , in this embodiment, the electric core includes an electrode assembly (i.e., a bare electric core) formed by coiling a negative electrode sheet 10, a separator 20, and a positive electrode sheet 30. The electrode assembly includes a planar region Q1 and corner regions Q2 located on both sides of the planar region Q1. At least one corner region Q2 of the electrode assembly is provided with a pore layer 40 for accumulating electrolyte, and the pore layer 40 is located between the negative electrode sheet 10 and the positive electrode sheet 30. Among them, the pore layer 40 presents a three-dimensional network structure microscopically and has a certain porosity, so the electrolyte can be accumulated in the pore layer 40.

[0035] During the cycling process of the electric core in this embodiment, when the negative electrode sheet 10 in the corner region Q2 gradually expands due to the insertion of lithium ions, since there is a pore layer 40 between the negative electrode sheet 10 and the positive electrode sheet 30, the pore layer 40 will keep the negative electrode sheet 10 and the positive electrode sheet 30 separated, and the negative electrode sheet 10 will not expand to closely contact the positive electrode sheet 30, ensuring the gap size between the negative electrode sheet 10 and the positive electrode sheet 30. At the same time, the electrolyte between the negative electrode sheet 10 and the positive electrode sheet 30 will be stored in the pore layer 40 and will not be squeezed to other places. Therefore, it can ensure that there is sufficient electrolyte between the negative electrode sheet 10 and the positive electrode sheet 30 in the corner region Q2. In this embodiment, the quantity and area size of the pore layer 40 provided in the corner region Q2 of the electrode assembly can be set differently according to different electric core specifications; one or more pore layers 40 can be provided between each adjacent negative and positive electrode sheets 10 in the corner region Q2, or one or more pore layers 40 can be provided between some of the negative and positive electrode sheets 10 in the corner region Q2; it can also be that only a pore layer 40 of corresponding size is provided in the region or part where stress concentration occurs in the corner region Q2; etc.

[0036] In the technical solution of the battery cell of this embodiment, a pore layer 40 for accumulating electrolyte is provided between the positive and negative electrode sheets 10 in the corner area Q2 of the electrode assembly, so that the negative electrode sheet 10 and the positive electrode sheet 30 in the corner area Q2 are always separated by the pore layer 40, ensuring the gap size between the negative electrode sheet 10 and the positive electrode sheet 30. Even if the negative electrode sheet 10 expands due to the insertion of lithium ions, the situation where the negative electrode sheet 10 squeezes out all the electrolyte between it and the positive electrode sheet 30 will not occur. Moreover, the pore layer 40 is a three-dimensional grid structure with a high porosity, which can store the electrolyte between the positive and negative electrode sheets 10 inside it, thereby ensuring sufficient electrolyte between the positive and negative electrode sheets 10, enabling the negative electrode sheet 10 and the positive electrode sheet 30 in the corner area Q2 to operate normally, effectively improving the deterioration of the electrode sheet interface and lithium plating caused by the lack of electrolyte in the corner area Q2, and further effectively enhancing the cycle performance of the battery cell.

[0037] Referring to Figure 1 , in some embodiments, the battery cell can be provided with pore layers 40 in both corner areas Q2 of the electrode assembly to improve the deterioration of the electrode sheet interface and lithium plating in both corner areas Q2, and further enhance the cycle performance of the battery cell. Of course, in other embodiments, it can also be that only a pore layer 40 is provided in one corner area Q2 of the electrode assembly, and the other corner area Q2 can adopt other solutions to improve the deterioration of the electrode sheet interface and lithium plating.

[0038] Referring to Figure 2 and Figure 3 , in some embodiments, at least one pore layer 40 is provided on the negative electrode sheet 10 in the corner area Q2; that is, among all the pore layers 40 in the two corner areas Q2 of the electrode assembly, at least one pore layer 40 is provided on the negative electrode sheet 10 in the corner area Q2. For example, there are a total of 7 pore layers 40 in the two corner areas Q2 of the electrode assembly, and 1, 2, 3, 4, 5, 6, or 7 pore layers 40 are provided on the negative electrode sheet 10; moreover, each of the pore layers 40 provided on the negative electrode sheet 10 can be a pore layer 40 in the same corner area Q2, or part of it can be a pore layer 40 in one corner area Q2 and the other part can be a pore layer 40 in the other corner area Q2; for example, if there are a total of 5 pore layers 40 provided on the negative electrode sheet 10, they can all be provided on the negative electrode sheet 10 in the same corner area Q2, or part (such as 3) of the pore layers 40 can be provided on the negative electrode sheet 10 in one corner area Q2, and the other part (such as 2) of the pore layers 40 can be provided on the negative electrode sheet 10 in the other corner area Q2. In addition, each of the pore layers 40 provided on the negative electrode sheet 10 can be provided on different layers of the negative electrode sheet 10 in the corner area Q2, or multiple pore layers 40 can be provided on the same layer of the negative electrode sheet 10 in the corner area Q2.

[0039] Refer to Figure 3 , in some embodiments, at least one pore layer 40 is disposed on the positive electrode sheet 30 within the corner region Q2; that is, among all the pore layers 40 within the two corner regions Q2 of the electrode assembly, at least one pore layer 40 is disposed on the positive electrode sheet 30 within the corner region Q2. For example, there are a total of 6 pore layers 40 within the two corner regions Q2 of the electrode assembly, and 1, 2, 3, 4, 5, or 6 of these pore layers 40 are disposed on the positive electrode sheet 30; moreover, each of the pore layers 40 disposed on the positive electrode sheet 30 can be a pore layer 40 within the same corner region Q2, or part of the pore layers 40 can be within one corner region Q2 and the other part within the other corner region Q2; for instance, if there are a total of 6 pore layers 40 disposed on the positive electrode sheet 30, it can be that all 6 pore layers 40 are disposed on the positive electrode sheet 30 within the same corner region Q2, or part (e.g., 3) of the pore layers 40 are disposed on the positive electrode sheet 30 within one corner region Q2 and the other part (e.g., 3) of the pore layers 40 are disposed on the positive electrode sheet 30 within the other corner region Q2. Additionally, each of the pore layers 40 disposed on the positive electrode sheet 30 can be disposed on different layers of the positive electrode sheet 30 within the corner region Q2 respectively, or multiple pore layers 40 can be disposed on the same layer of the positive electrode sheet 30 within the corner region Q2.

[0040] In some embodiments, at least one pore layer 40 is disposed on the separator 20 within the corner region Q2; that is, among all the pore layers 40 within the two corner regions Q2 of the electrode assembly, at least one pore layer 40 is disposed on the separator 20 within the corner region Q2. For example, there are a total of 9 pore layers 40 within the two corner regions Q2 of the electrode assembly, and 1, 2, 3, 4, 5, 6, 7, 8, or 9 of these pore layers 40 can be disposed on the separator 20; moreover, each of the pore layers 40 disposed on the separator 20 can be a pore layer 40 within the same corner region Q2, or part of the pore layers 40 can be within one corner region Q2 and the other part within the other corner region Q2; for instance, if there are a total of 7 pore layers 40 disposed on the separator 20, it can be that all 7 pore layers 40 are disposed on the separator 20 within the same corner region Q2, or part (e.g., 3) of the pore layers 40 are disposed on the separator 20 within one corner region Q2 and the other part (e.g., 4) of the pore layers 40 are disposed on the separator 20 within the other corner region Q2. Additionally, each of the pore layers 40 disposed on the separator 20 can be disposed on different layers of the separator 20 within the corner region Q2 respectively, or multiple pore layers 40 can be disposed on the same layer of the separator 20 within the corner region Q2.

[0041] Refer to Figure 3, in some embodiments, there is a pore layer 40 between each adjacent positive and negative electrode sheets 10 in the corner area Q2; that is, there is at least one pore layer 40 between each layer of positive electrode sheet 30 and its adjacent negative electrode sheet 10 in the corner area Q2. The pore layer 40 between adjacent positive and negative electrode sheets 10 can be provided on the surface of the positive electrode sheet 30, or on the surface of the negative electrode sheet 10, or on the surface of the separator 20. In the solution of this embodiment, by providing a pore layer 40 between each adjacent positive electrode sheet 30 and negative electrode sheet 10 in the corner area Q2, each layer of negative electrode sheet 10 in the corner area Q2 is separated from the positive electrode sheet 30 by the pore layer 40, ensuring the gap size between each layer of negative electrode sheet 10 and the positive electrode sheet 30 in the corner area Q2. During the cycling process of the battery cell, each layer of negative electrode sheet 10 in the corner area Q2 will not squeeze away the electrode liquid between it and the positive electrode sheet 30 due to expansion. Furthermore, it ensures that the interface of each layer of electrode sheet in the corner area Q2 will not deteriorate and lithium deposition will not occur, better improving the situation of electrode sheet interface deterioration and lithium deposition caused by the lack of electrolyte in the corner area Q2, and further enhancing the cycling performance of the battery cell.

[0042] In some embodiments, a pore layer 40 is provided on each layer of negative electrode sheet 10 in the corner area Q2. Among them, when the pore layer 40 on one layer of negative electrode sheet 10 is one or more, the pore layer 40 on the negative electrode sheet 10 can be located on the same surface of the negative electrode sheet 10; when the pore layer 40 on one layer of negative electrode sheet 10 is multiple, the pore layer 40 on the negative electrode sheet 10 can be distributed on both surfaces of the negative electrode sheet 10.

[0043] In some embodiments, a pore layer 40 is provided on each layer of positive electrode sheet 30 in the corner area Q2. Among them, when the pore layer 40 on one layer of positive electrode sheet 30 is one or more, the pore layer 40 on the positive electrode sheet 30 can be located on the same surface of the positive electrode sheet 30; when the pore layer 40 on one layer of positive electrode sheet 30 is multiple, the pore layer 40 on the positive electrode sheet 30 can be distributed on both surfaces of the positive electrode sheet 30.

[0044] In some embodiments, the pore layer 40 on the separator 20 is located on either one or both surfaces of the separator 20. That is, when the pore layer 40 on one layer of separator 20 is one or more, the pore layer 40 on the separator 20 can be located on the same surface of the separator 20; when the pore layer 40 on one layer of separator 20 is multiple, the pore layer 40 on the separator 20 can be distributed on both surfaces of the separator 20.

[0045] In some embodiments, within the same corner region Q2, a plurality of pore layers 40 are provided between at least one layer of the negative electrode sheet 10 and an adjacent layer of the positive electrode sheet 30, and the plurality of pore layers 40 are distributed at intervals along the negative electrode sheet 10. Among them, the plurality of pore layers 40 can be distributed at intervals in any direction along the surface of the negative electrode sheet 10; for example, the plurality of pore layers 40 are distributed along the arc length direction of the negative electrode sheet 10, or the plurality of pore layers 40 are distributed along the width length direction of the negative electrode sheet 10; or the plurality of pore layers 40 are distributed in other directions along the surface of the negative electrode sheet 10. Among them, the plurality of pore layers 40 can be wholly or partially disposed on the surface of the positive electrode sheet 30, the surface of the negative electrode sheet 10, or the surface of the separator 20.

[0046] Of course, when designing the battery cell, specifically which positions within the corner region Q2 of the electrode assembly to set the pore layer 40 can be determined according to the stress distribution of the corner region Q2 of the current model battery cell and the factor of the comprehensive energy density of the battery cell, so as to obtain a battery cell with better comprehensive performance of energy density and cycle life.

[0047] In some embodiments, the pore layer 40 is made of an electrospun membrane. Since the electrospun membrane has a soft material and presents a three-dimensional network structure microscopically and has a very high porosity, therefore, the electrospun membrane can store a large amount of electrolyte; and, due to its material characteristics, the electrospun membrane can play a role similar to that of a sponge between the electrode sheets, alleviating the reduction of the gap between the electrode sheets and the squeezing out of the electrolyte caused by the expansion of the electrode sheets during charge and discharge; in summary, using the electrospun membrane as the pore layer 40 can better ensure sufficient electrolyte between the positive and negative electrode sheets 10 in the corner region Q2 of the electrode assembly, better avoid the occurrence of electrolyte shortage in the corner region Q2 of the electrode assembly, better improve the lithium deposition situation in the corner region Q2 of the electrode assembly, and improve the cycle performance of the battery cell.

[0048] Of course, in some other embodiments, the pore layer 40 can also adopt other material structures with similar characteristics to the electrospun membrane, which have the function of accumulating electrolyte and do not react with the internal components of the electrode assembly.

[0049] In some embodiments, the material of the electrospun membrane can be any one or any combination of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, and polyimide. Of course, the electrospun membrane can also be made of other materials with similar properties to the above-listed materials.

[0050] In some embodiments, the thickness of the pore layer 40 is 2 to 20 micrometers. The thickness of the pore layer 40 can be selected according to the comprehensive requirements of the specific specifications, energy density, cycle performance, etc. of the battery cell.

[0051] In some embodiments, the porosity of the pore layer 40 is 40% to 80%.

[0052] In some embodiments, the width of the pore layer 40 is 30% to 100% of the arc length of the adjacent electrode tab within the current corner region Q2. The width of the pore layer 40 can be selected appropriately according to the size of the stress concentration region in the corner region Q2.

[0053] In some embodiments, the length of the pore layer 40 is greater than or equal to the width of the positive electrode tab 30 and less than or equal to the width of the separator 20. Since the width of the negative electrode tab 10 of the battery cell is usually slightly larger than the width of the positive electrode tab 30, the length of the pore layer 40 only needs to be greater than or equal to the width of the positive electrode tab 30, which can ensure that all positions in the width direction of the positive electrode tab 30 will not be squeezed by the expansion of the negative electrode tab 10.

[0054] It should be noted that for the above various embodiments of the battery cell of the present utility model, without conflict with each other, the above embodiments can be arbitrarily combined or combined to form new embodiments.

[0055] The following presents the comparison of the results of the same cycle test between 4 groups of improved battery cells adopting the technical solution of the present application and 1 group of comparative battery cells not adopting the technical solution of the present application; among them, the battery cell model selected for each group of battery cells is 506687, the width of the positive electrode tab 30 is 76.5 mm, and the width of the negative electrode tab 10 is 78.5 mm.

[0056] Improved Group 1: This battery cell adopts the pore layer 40 disposed on the surface (inner surface and / or outer surface) of each layer of the negative electrode tab 10 in the corner region Q2 of the electrode assembly, that is, the pore layer 40 is disposed on the surface of each layer of the negative electrode tab 10 in the corner region Q2. The pore layer 40 is made of polyvinylidene fluoride material, the porosity of the pore layer 40 is 58%, the thickness of the pore layer 40 is 7 μm, the length of the pore layer 40 is equal to the width of the negative electrode tab 10, and the width of each pore layer 40 is 70% of the arc length of the corresponding layer of the negative electrode tab 10.

[0057] Improved Group 2: This battery cell adopts the pore layer 40 disposed on the surface (inner surface and / or outer surface) of each layer of the positive electrode tab 30 in the corner region Q2 of the electrode assembly, that is, the pore layer 40 is disposed on the surface of each layer of the positive electrode tab 30 in the corner region Q2. The pore layer 40 is made of polyvinylidene fluoride - hexafluoropropylene copolymer material, the porosity of the pore layer 40 is 63%, the thickness of the pore layer 40 is 10 μm, the length of the pore layer 40 is equal to the width of the positive electrode tab 30, and the width of each pore layer 40 is 60% of the arc length of the corresponding layer of the positive electrode tab 30.

[0058] Improvement Group 3: In this battery cell, the pore layer 40 is disposed on the surfaces (inner surface and / or outer surface) of each layer of the positive electrode sheet 30 and each layer of the negative electrode sheet 10 in the corner area Q2 of the electrode assembly. That is, the pore layer 40 is provided on the surfaces of each layer of the positive electrode sheet 30 and each layer of the negative electrode sheet 10 in the corner area Q2. The pore layer 40 is made of polyacrylonitrile. The porosity of the pore layer 40 is 48%, the thickness of the pore layer 40 is 4 microns, the length of the pore layer 40 is equal to the width of the separator 20, and the width of each pore layer 40 is 70% of the arc length of the corresponding layer of the electrode sheet.

[0059] Improvement Group 4: In this battery cell, the pore layer 40 is disposed on the surface of each layer of the negative electrode sheet 10 facing the outside of the electrode assembly (i.e., the side facing away from the planar area Q1 of the electrode assembly) in the corner area Q2 of the electrode assembly. That is, the pore layer 40 is provided on the surface of each layer of the negative electrode sheet 10 facing the outside of the electrode assembly. The pore layer 40 is made of polymethyl methacrylate. The porosity of the pore layer 40 is 61%, the thickness of the pore layer 40 is 8 microns, the length of the pore layer 40 is equal to the width of the negative electrode sheet 10, and the width of each pore layer 40 is 50% of the arc length of the corresponding layer of the negative electrode sheet 10.

[0060] Comparison Group 1: In the electrode assembly of this battery cell, the pore layer 40 is not added, and the other conditions are the same as those of each improvement group.

[0061] The above 5 groups of battery cells (i.e., Improvement Groups 1-4 and Comparison Group 1) are subjected to 2C / 1C cyclic charge and discharge, and the attenuation and corner lithium deposition conditions after 800 cycles are compared. After 800 cycles of the battery cells, the capacity retention rates of the battery cells in Improvement Groups 1 to 4 are 83.1%, 81.5%, 82.6%, and 81.2% respectively, and no lithium deposition in the corner area Q2 and deterioration of the electrode sheet interface are found after disassembling the battery cells. While the capacity retention rate of the battery cell in Comparison Group 1 is 71.8%, and lithium deposition in the corner area Q2 and deterioration of the electrode sheet interface are found after disassembling the battery cell. It can be seen that the technical solution of the battery cell of the present application effectively improves the cycling performance of the battery cell and effectively improves the lithium deposition in the corner area Q2 and the deterioration of the electrode sheet interface.

[0062] The present utility model also provides a battery, including a housing and the above-mentioned battery cell. The battery cell is installed in the housing. The specific structure of the battery cell refers to the above-mentioned embodiments. Since this battery adopts all the technical solutions of all the above-mentioned embodiments of the battery cell, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be elaborated here one by one.

[0063] The above are only some or preferred embodiments of the present utility model. Neither the text nor the drawings can limit the scope of protection of the present utility model. Any equivalent structural transformation made by using the content of the specification and drawings of the present utility model under the concept of an integral whole of the present utility model, or any direct / indirect application in other related technical fields, is included in the scope of protection of the present utility model.

Claims

1. A battery cell, comprising an electrode assembly formed by winding a negative electrode sheet, a separator and a positive electrode sheet together, wherein the electrode assembly comprises a plane area and corner areas located on both sides of the plane area, characterized in that: A porous layer for storing electrolyte is provided in at least one of the corner regions, and the porous layer is located between the negative electrode sheet and the positive electrode sheet.

2. The battery cell according to claim 1, characterized in that: The porous layer is arranged in both the corner areas.

3. The battery cell according to claim 1, characterized in that: At least one of the pore layers is disposed on the negative electrode sheet in the corner area; and / or, At least one of the porous layers is disposed on the positive electrode sheet in the corner area; and / or, At least one of the porous layers is disposed on the diaphragm in the corner region.

4. The battery cell according to claim 3, characterized in that: The pore layer is provided between each adjacent positive and negative electrode sheets in the corner area; and / or, Each layer of negative electrode sheets in the corner area is provided with the porous layer; and / or, The porous layer is provided on each layer of the positive electrode sheet in the corner area.

5. The battery cell according to claim 3, characterized in that: The porous layer on the negative electrode sheet is located on one side or both sides of the negative electrode sheet; and / or, The porous layer on the positive electrode sheet is located on any one side or both sides of the positive electrode sheet; and / or, The porous layer on the diaphragm is located on either or both sides of the diaphragm.

6. The battery cell according to claim 1, characterized in that: In the same corner area, a plurality of the porous layers are provided between at least one layer of the negative electrode sheet and an adjacent layer of the positive electrode sheet, and the plurality of porous layers are spaced apart and distributed along the winding length direction of the negative electrode sheet.

7. The battery cell according to claim 1, characterized in that: The porous layer is an electrostatic spinning membrane.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The thickness of the porous layer is 2 to 20 micrometers; and / or, The porosity of the porous layer is 40% to 80%; and / or, The width of the aperture layer along the winding direction of the pole piece is 30% to 100% of the arc length of the inner adjacent pole piece in the current corner area; and / or, The length dimension of the pore layer along the axial direction of the battery core is greater than or equal to the width dimension of the positive electrode sheet, and less than or equal to the width dimension of the separator.

9. A battery, characterized in that: The invention comprises a shell and the battery cell according to any one of claims 1 to 8, wherein the battery cell is installed in the shell.

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