Battery

Abstract

A battery comprises a negative electrode active material layer, a positive electrode active material layer and a separator between the positive electrode active material layer and the negative electrode active material layer. The negative electrode active material layer comprises a first part and a second part. The second part comprises a first surface and a first end. The first surface is connected to the first part through a first connection, and the first end is away from the first connection and is one end of the negative electrode active material layer. The thickness of the second part decreases from the first connection toward the first end. The positive electrode active material layer comprises a third part and a fourth part, and the fourth part comprises a second surface and a second end. The second surface is at least partially opposite to the second surface, and is connected to the third part through a second connection, and the second end is away from the second connection and is one end of the positive electrode active material layer. The thickness of the fourth part gradually decreases from the second connection toward the second end. The first connection is located between the second connection and the second end. The battery of the present application is conducive to suppressing lithium precipitation while maintaining the energy density of the battery.

Description

Technical Field

[0001] The present application relates to a battery. Background Art

[0002] Lithium-ion batteries have many advantages such as high energy density, long cycle life, high nominal voltage, low self-discharge rate, small size, and light weight, and are widely used in the field of consumer electronics. In lithium batteries, in order to suppress lithium plating, the size of the active material layer of the negative electrode sheet is usually larger than that of the active material layer of the positive electrode sheet. On the other hand, from the perspective of improving the energy density of lithium batteries, the smaller the size difference between the active material layer of the negative electrode sheet and the active material layer of the positive electrode sheet, the better. However, while maintaining the edge of the active material layer of the negative electrode sheet beyond the edge of the active material layer of the positive electrode sheet, the size difference between the active material layer of the negative electrode sheet and the active material layer of the positive electrode sheet is as small as possible. In terms of manufacturing process, especially the process of winding type batteries, the requirements for manufacturing process precision are relatively high, otherwise lithium plating will occur at the edge of the negative electrode sheet of the battery, reducing the safety performance of the battery. Summary of the invention

[0003] In view of the above situation, it is necessary to provide a battery that is beneficial to suppressing the occurrence of lithium plating and at the same time maintaining a high energy density.

[0004] The present application provides a battery, comprising a negative electrode active material layer, a positive electrode active material layer, and a separator between the positive electrode active material layer and the negative electrode active material layer. The negative electrode active material layer includes a first portion and a second portion connected to the first portion along a first direction. The second portion includes a first surface and a first end. The first surface is connected to the first portion through a first connection, and the first end is away from the first connection and is one end of the negative electrode active material layer. The thickness of the second portion in a second direction perpendicular to the first direction gradually decreases from the first connection to the first end along the first direction. The positive electrode active material layer includes a third portion and a fourth portion connected to the third portion along the first direction, and the fourth portion includes a second surface and a second end. The second surface is connected to the third portion through a second connection, and the second end is away from the second connection and is one end of the positive electrode active material layer. The thickness of the fourth portion in the second direction gradually decreases from the second connection to the second end along the first direction. The first surface and the second surface are at least partially arranged facing each other, and in the first direction, the first connection is located between the second connection and the second end.

[0005] As a solution of the present application, in the first direction, the second end is located between the first connection point and the first end.

[0006] As a solution of the present application, the first part includes a third surface, and the third part includes a fourth surface. The third surface is connected to the first surface via a first connection, and the fourth surface is connected to the second surface via a second connection; the third surface and the fourth surface are at least partially disposed facing each other.

[0007] As a solution of the present application, the third surface and the fourth surface at least partially overlap in the second direction; the first surface and the second surface at least partially overlap in the second direction; the third surface and the second surface at least partially overlap in the second direction.

[0008] As a solution of the present application, the distance from the third surface to the fourth surface along the second direction is the first distance, and the distance from the first surface to the second surface along the second direction is the second distance, wherein the first distance is not equal to the second distance.

[0009] As a solution of the present application, the first distance is smaller than the second distance.

[0010] As a solution of the present application, the distance from the third surface to the second surface along the second direction is a third distance, wherein the third distance is not equal to the first distance.

[0011] As a solution of the present application, the third distance is greater than the first distance.

[0012] As a solution of the present application, the third distance is not equal to the second distance.

[0013] As a solution of the present application, the third distance is smaller than the second distance.

[0014] As a scheme of the present application, when observed along the second direction, the first end has a first region having a first spacing from the second end in the first direction, and a second region having a second spacing from the second end in the first direction, wherein the first spacing is not equal to the second spacing.

[0015] As a solution of the present application, when viewed along the second direction, the second end has a plurality of protrusions.

[0016] As a solution of the present application, the battery also includes a first layer, the first layer is bonded to the second end and the second surface, and continuously covers the second end and the second surface, and the first layer can block the conduction of ions.

[0017] As a solution of the present application, the first layer is further bonded to the fourth surface and covers at least a portion of the fourth surface.

[0018] As a scheme of the present application, the battery also includes a positive electrode current collector, which is located on the side of the positive electrode active material layer away from the first surface and the third surface, and the positive electrode current collector includes a first area where the positive electrode active material layer is arranged and a second area located on the side of the second end away from the second connection point in the first direction, the positive electrode active material layer is not arranged in the second area, and the first layer is also bonded to the second area and covers at least part of the second area.

[0019] As a scheme of the present application, the first layer includes a third end and a fourth end arranged opposite to each other in the first direction, wherein in the first direction, the third end is located on a side of the second connection away from the second end, and the fourth end is located on a side of the second connection away from the third end, wherein, when observed along the second direction, the distance from the second end to the third end is a fourth distance, the distance from the second end to the fourth end is a fifth distance, and the fourth distance is not equal to the fifth distance.

[0020] As a solution of the present application, the fourth distance is smaller than the fifth distance.

[0021] As a scheme of the present application, the fourth surface includes a third zone, a step zone and a fourth zone connected in sequence along the first direction, and the thickness of the part of the positive electrode active material layer corresponding to the fourth zone in the second direction is less than the thickness of the positive electrode active material layer corresponding to the third zone; observed from the second direction, the fourth zone is located between the step zone and the first connection, and the first layer covers the fourth zone.

[0022] As a solution of the present application, the thickness of the first layer in the second direction is greater than the height of the discontinuity region in the second direction.

[0023] As a solution of the present application, the portion of the blocking first layer located in the fourth zone includes a fifth surface, the fifth surface is away from the fourth zone, and the fifth surface includes a portion whose distance to the third zone in the second direction is greater than the distance to the third surface in the second direction.

[0024] The battery of the present application, wherein the first connection point of the negative electrode active material layer is located between the second connection point of the positive electrode active material layer and the second end of the positive electrode active material layer in the first direction, is beneficial for suppressing lithium plating while maintaining the battery energy density. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a battery according to one embodiment of the present application.

[0026] Figure 2 It is a cross-sectional schematic diagram of a battery according to one embodiment of the present application.

[0027] Figure 3 A battery according to one embodiment of the present application is Figure 2 A local enlarged schematic diagram of position III in the figure.

[0028] Figure 4a A battery according to one embodiment of the present application is Figure 2 Schematic diagram of a local top view at position III in FIG.

[0029] Figure 4b A battery according to an embodiment of the present application Figure 3 Local cross-sectional view along the IV-IV direction.

[0030] Figure 5 A battery according to one embodiment of the present application is Figure 2 Schematic diagram of a local top view at position III in FIG.

[0031] Figure 6 A battery according to one embodiment of the present application is Figure 2 Schematic diagram of a local top view at position III in FIG.

[0032] Figure 7 A battery according to one embodiment of the present application is Figure 2 Schematic diagram of the cross section at position III in FIG.

[0033] Figure 8 A battery according to one embodiment of the present application is Figure 7 A local enlarged schematic diagram of position VIII in FIG.

[0034] Figure 9a A battery according to one embodiment of the present application is Figure 7 Schematic diagram of a partial top view at position VIII in FIG.

[0035] Figure 9b A battery according to an embodiment of the present application Figure 8 Local cross-sectional view along the IX-IX direction.

[0036] Fig.10 A battery according to one embodiment of the present application is Figure 7 A local enlarged schematic diagram of position VIII in FIG.

[0037] Fig.11 A battery according to one embodiment of the present application is Figure 2 A local enlarged schematic diagram of the XI position in FIG.

[0038] Fig.12 A battery according to one embodiment of the present application is Figure 2 Schematic diagram of a local top view at the XI position in FIG.

[0039] Main component symbols

[0040]

[0041]

[0042] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0043] The technical scheme in the embodiment of the present application is described clearly and in detail below. Obviously, the described embodiment is only a part of the embodiment of the present application, rather than all the embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present application. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0044] Hereinafter, the embodiments of the present application will be described in detail. However, the present application can be embodied in many different forms and should not be construed as being limited to the exemplary embodiments illustrated herein. Rather, these exemplary embodiments are provided so that the present application is thoroughly and in detail communicated to those skilled in the art.

[0045] In addition, for simplicity and clarity, in the accompanying drawings, the size or thickness of various components, layers may be amplified. Throughout the entire text, the same numerical value refers to the same element. As used herein, the term "and / or", "and / or" includes any and all combinations of one or more related enumerated items. In addition, it should be understood that when element A is referred to as "connecting" element B, element A may be directly connected to element B, or there may be an intermediate element C and element A and element B may be indirectly connected to each other.

[0046] Further, the use of “may” when describing embodiments of the present application means “one or more embodiments of the present application”.

[0047] The technical terms used herein are for the purpose of describing specific embodiments and are not intended to limit the present application. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. It should be further understood that the term "comprising", when used in this specification, refers to the presence of narrated features, values, steps, operations, elements and / or components, but does not exclude the presence or increase of one or more other features, values, steps, operations, elements, components and / or combinations thereof.

[0048] Spatially related terms, such as "above" and the like, may be used herein for convenience of description to describe the relationship of one element or feature to another element (or elements) or feature (or features) as illustrated in the figure. It should be understood that in addition to the directions described in the figures, spatially related terms are intended to include different orientations of the device or apparatus in use or operation. For example, if the device in the figure is turned over, the elements described as "above" or "on" other elements or features will be oriented "below" or "below" the other elements or features. Therefore, the exemplary term "above" may include both above and below directions.

[0049] It should be understood that when an element or layer is referred to as being "on", "connected to", "coupled to", or "adjacent to" another element or layer, the element or layer may be "directly on", "directly coupled to", "directly connected to", "directly coupled to", or "directly adjacent to" another element or layer, or one or more intermediate elements or layers may be present. In addition, "connected", "connected", etc. may also mean "electrically connected", "electrically connected", etc. based on what they are used as will be understood by those skilled in the art. In addition, when an element, component, region, layer, and / or portion is referred to as being "between" two elements, components, regions, layers, and / or portions, it may be the only element, component, region, layer, and / or portion between the two elements, components, regions, layers, and / or portions, or one or more intermediate elements, components, regions, layers, and / or portions may also be present.

[0050] It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts herein, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part without departing from the teaching of the exemplary embodiment.

[0051] In the present application, the first direction X and the third direction Z are perpendicular to each other and parallel to the main plane of the electrode assembly, and the second direction Y is perpendicular to the main plane of the electrode assembly, that is, the thickness direction of the electrode assembly. The main plane of the electrode assembly is the surface of the flat part of the electrode assembly ( Figure 1 The thickness direction of the electrode assembly is the stacking direction of the pole pieces in the flat portion of the electrode assembly.

[0052] Some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0053] See also Figure 1 and Figure 2 , the battery 100 includes an electrode assembly 100A. Figure 2 for Figure 1 In the cross section of the plane where the battery 100 is located along the X direction and the Y direction, the electrode assembly 100A includes a negative electrode sheet 10A, a positive electrode sheet 30A, and a separator 50 located between the positive electrode sheet 10A and the negative electrode sheet 30A. The separator 50 is an electrical insulating material, and ions can pass through the separator 50.

[0054] The positional relationship between the negative electrode tab 10A and the positive electrode tab 30A will be further described below.

[0055] like Figure 1 As shown, the negative electrode sheet 10A, the separator 50 and the positive electrode sheet 30A are stacked to form a stack, and the stack is then wound multiple times around a central axis OO along a third direction Z to form an electrode assembly 100A.

[0056] The electrode assembly 100A includes a flat portion 100AA and a plurality of bent end portions 100AB in the X direction. The plurality of bent end portions 100AB are respectively distributed on opposite sides of the center of the flat portion 100AA of the battery 100 in the X direction. Figure 2 In the middle, they are the left and right sides respectively.

[0057] The negative electrode sheet 10A is further described below.

[0058] See also Figure 2 The negative electrode sheet 10A includes a negative electrode active material layer 10 and a negative electrode current collector 10a. The negative electrode active material layer 10 is disposed on the surface of the negative electrode current collector 10a.

[0059] The negative electrode current collector 10a is conductive and includes a conductive material. The conductive material, for example, may include at least one or more of conductive metals such as nickel, copper, and alloys thereof. In some embodiments, the negative electrode current collector 10a, for example, may include at least one or two of conductive metal sheets such as nickel foil and copper foil, but is not limited thereto. The negative electrode current collector 10a includes a first surface 10aa and a second surface 10ab facing each other. The first surface 10aa of the negative electrode current collector 10a includes a first region 10a1 and a second region 10a2, and the second surface 10ab of the negative electrode current collector 10a includes a first region 10a1 and a second region 10a2. The first region 10a1 is a region for setting active materials to form an active material layer, and the second region 10a2 is a region where no active material layer is formed. In some embodiments, the first surface 10aa may include two second regions 10a2 respectively connected to the two ends of the first region 10a1 of the first surface 10aa, and the second surface 10ab may include two second regions 10a2 respectively connected to the two ends of the first region 10a1 of the second surface 10ab. The area of ​​the first region 10a1 of the first surface 10aa may be greater than the area of ​​the first region 10a1 of the second surface 10ab.

[0060] The negative electrode active material layer 10 is disposed in the first region 10a1 of the first surface 10aa of the negative electrode current collector 10a and the first region 10a1 of the second surface 10ab. The negative electrode active material layer 10, for example, may include at least but not limited to one or more of graphite, soft carbon, hard carbon, graphene, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate, or other metals that can form alloys with lithium.

[0061] Preferably, the thickness of the negative electrode current collector 10 a may be 2 micrometers to 13 micrometers, and the thickness of the negative electrode active material layer 10 may be 80 micrometers to 300 micrometers.

[0062] In some embodiments, the ratio of the thickness of the negative electrode active material layer 10 to the thickness of the negative electrode current collector 10a may be 5 to 30, which is beneficial to reduce the proportion of the thickness of the negative electrode current collector 10a in the overall thickness of the battery, thereby facilitating the improvement of the energy density of the battery.

[0063] Please also see Figure 3 , the negative electrode active material layer 10 includes a first portion 11 and a second portion 13 connected to the first portion 11 along the first direction X. The second portion 13 includes a first surface 130 and a first end 131, and the first portion 11 includes a third surface 110. The third surface 110 is connected to the first surface 130 through a first connection 101. The first end 131 is an end of the second portion 13 away from the first connection 101, and the first end 131 is an end of the negative electrode active material layer 10.

[0064] The thickness of the second portion 13 in the second direction Y perpendicular to the first direction X decreases from the first connection point 101 toward the first end 131 along the first direction X. That is, the first connection point 101 is where the thickness of the second portion 13 in the second direction Y begins to decrease along the first direction X. In some embodiments, the thickness of the second portion 13 in the second direction Y decreases monotonically along the first direction X from the first connection point 101 toward the first end 131, which may be a linear decrease or a curved decrease.

[0065] The first end 131 is located in the flat portion 100AA when viewed along the second direction Y. The negative active material layer 10 is disposed on the first region 10a1 , and a second region 10a2 is disposed on a side of the first end 131 away from the first connection portion 101 in the first direction X.

[0066] The positive electrode sheet 30A is further described below.

[0067] See also Figure 2 The positive electrode sheet 30A includes a positive electrode active material layer 30 and a positive electrode current collector 30a. The positive electrode active material layer 30 is disposed on the surface of the positive electrode current collector 30a.

[0068] The positive electrode current collector 30a is conductive and includes a conductive material. The conductive material, for example, may include at least one or more of conductive metals such as aluminum, copper, nickel, and alloys thereof. In some embodiments, the positive electrode current collector 30a, for example, may include at least one or more of conductive metal sheets such as, but not limited to, aluminum mesh, aluminum foil, copper mesh, copper foil, nickel foil, etc. The positive electrode current collector 30a includes a first surface 30aa and a second surface 30ab facing each other. The first surface 30aa of the positive electrode current collector 30a includes a first area 30a1 and a second area 30a2, and the second surface 30ab of the positive electrode current collector 30a includes a first area 30a1 and a second area 30a2. The first area 30a1 is a region for arranging active materials to form an active material layer, and the second area 30a2 is a region where an active material layer is not formed. In some embodiments, the first surface 30aa may include two second regions 30a2 respectively connected to the two ends of the first region 30a1 of the first surface 30aa, and the second surface 30ab may include two second regions 30a2 respectively connected to the two ends of the first region 30a1 of the second surface 30ab. The area of ​​the first region 30a1 of the first surface 30aa may be smaller than the area of ​​the first region 30a1 of the second surface 30ab.

[0069] The positive electrode active material layer 30 is disposed in the first region 30a1 of the first surface 30aa of the positive electrode current collector 30a and the first region 30a1 of the second surface 30ab. The positive electrode active material layer 30, for example, may include at least but not limited to one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel oxide, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium iron phosphate and lithium-rich manganese-based materials.

[0070] Preferably, the thickness of the positive electrode current collector 30 a may be 3 micrometers to 15 micrometers, and the thickness of the positive electrode active material layer 30 may be 80 micrometers to 300 micrometers.

[0071] In some embodiments, the ratio of the thickness of the positive active material layer 30 to the thickness of the positive current collector 30a may be 5 to 30, which is beneficial to reduce the proportion of the thickness of the positive current collector 30a in the overall thickness of the battery, thereby facilitating the improvement of the energy density of the battery.

[0072] Please also see Figure 3 , the positive electrode active material layer 30 includes a third portion 31 and a fourth portion 33 connected to the third portion 31 along the first direction X. The fourth portion 33 includes a second surface 330 and a second end 331, and the third portion 31 includes a fourth surface 310. The fourth surface 310 is connected to the second surface 330 through the second connection 301. The second end 331 is an end of the fourth portion 33 away from the second connection 301, and the second end 331 is an end of the positive electrode active material layer 30.

[0073] The thickness of the fourth portion 33 in the second direction Y decreases from the second connection point 301 toward the second end 331 along the first direction X. That is, the second connection point 301 is where the thickness of the fourth portion 33 in the second direction Y begins to decrease along the first direction X. In some embodiments, the thickness of the fourth portion 33 in the second direction Y decreases monotonically from the second connection point 301 toward the second end 331 along the first direction X, which may be a linear decrease or a curved decrease.

[0074] Viewed along the second direction Y, the second end 331 is located in the flat portion 100AA.

[0075] The positive electrode active material layer 30 is disposed on the first region 30 a 1 , and a second region 30 a 2 is disposed on a side of the second end 331 away from the second connection portion 301 in the first direction X.

[0076] In the present embodiment, the first surface 10aa of the negative electrode current collector 10a is disposed toward the second surface 30ab of the positive electrode current collector 30a, and the second surface 10ab of the negative electrode current collector 10a is disposed toward the first surface 30aa of the positive electrode current collector 30a.

[0077] The separator 50 is located between the negative electrode active material layer 10 and the positive electrode active material layer 30. The separator 50 contains an electrical insulating material, for example, at least including but not limited to one or more of polyethylene, polypropylene, polyethylene terephthalate, polyimide and aramid. For example, polyethylene includes at least one component selected from high-density polyethylene, low-density polyethylene and ultra-high molecular weight polyethylene. In particular, polyethylene and polypropylene have a good effect on preventing short circuits and can improve the stability of lithium-ion batteries through a shutdown effect.

[0078] The surface of the isolation membrane may also include a porous layer, which is disposed on at least one surface of the isolation membrane, and the porous layer includes inorganic particles and a binder, and the inorganic particles may be selected from, but not limited to, aluminum oxide (Al2O3), silicon oxide (SiO2), magnesium oxide (MgO), titanium oxide (TiO2), hafnium dioxide (HfO2), tin oxide (SnO2), cerium dioxide (CeO2), nickel oxide (NiO), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide (ZrO2), yttrium oxide (Y2O3), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate. The binder may be selected from, but not limited to, a combination of one or more of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.

[0079] The porous layer can improve the heat resistance, oxidation resistance and electrolyte wetting performance of the separator, and enhance the adhesion between the separator and the positive electrode or the negative electrode.

[0080] In this embodiment, the isolation film 50 is a film layer including a plurality of holes, such as Figure 2 As shown, each break on the isolation film 50 is a hole.

[0081] In this embodiment, the separator 50 in the drawings does not contact the negative electrode active material layer 10 and the positive electrode active material layer 30 , respectively. However, in some embodiments, the separator 50 may contact at least a portion of the negative electrode active material layer 10 and the positive electrode active material layer 30 .

[0082] The following description takes the first end 131 as the end of the negative electrode active material layer 10 close to the end section of the wound electrode assembly 100A, and the second end 331 as the end of the positive electrode active material layer 30 close to the end section III of the wound electrode assembly 100A.

[0083] The negative electrode active material layer 10 and the positive electrode active material layer 30 are disposed opposite to each other. Figure 3, the first surface 130 and the second surface 330 are at least partially arranged opposite to each other, that is, when viewed from the second direction Y, the first surface 130 and the second surface 330 at least partially overlap. The third surface 110 and the fourth surface 310 are at least partially arranged opposite to each other, that is, when viewed from the second direction Y, the third surface 110 and the fourth surface 310 at least partially overlap. In the first direction X, the first connection 101 is located between the second connection 301 and the second end 331. In combination with the thickness of the second portion 13 in the second direction Y perpendicular to the first direction X decreasing from the first connection 101 to the first end 131 along the first direction X, the thickness of the fourth portion 33 in the second direction Y decreasing from the second connection 301 to the second end 331 along the first direction X is conducive to suppressing lithium deposition while maintaining the energy density of the battery 100.

[0084] In this embodiment, in the first direction X, the second end 331 may be located between the first connection point 101 and the first end 131, that is, when viewed from the second direction Y, the first surface 130 and the second surface 330 at least partially overlap, which is further beneficial to suppress lithium deposition in the battery.

[0085] The negative electrode active material layer 10 is separated from the positive electrode active material layer 30. The distance from the third surface 110 to the fourth surface 310 along the second direction Y is a first distance D1, the distance from the first surface 130 to the second surface 330 along the second direction Y is a second distance D2, and the distance from the third surface 110 to the second surface 330 along the second direction Y is a third distance D3. Among them, D1 is not equal to D2, and D1 is not equal to D3. Specifically, D2 is greater than D1, D3 is greater than D1, and D3 is not equal to D2. More specifically, D3 is less than D2.

[0086] See also Figure 4a , Figure 5 and Figure 6 , viewed from the second direction Y, the first end 131 and the second end 331 may be arranged in parallel or not. Observed from the second direction Y, the first end 131 may be in a straight line or in a non-zero degree curve in the third direction Z, and the second end 331 may be in a straight line or in a non-zero degree curve.

[0087] In this implementation, see Figure 4a , viewed from the second direction Y, the first end 131 has a first region with a first spacing E1 from the second end 331 in the first direction X, and the first end 131 also has a second region with a second spacing E2 from the second end 331 in the first direction X. E1 and E2 are not equal. Figure 4b It is a partial cross-sectional top view of the battery along the plane of the X direction and the Z direction, and the cross section is the positive electrode active material layer 30. Figure 4bIn the embodiment, the distance from one end of the positive electrode active material layer 30 close to the first end 131 to the first end 131 along the first direction X is greater than the distance from the second end 331 to the first end 131 along the first direction X.

[0088] For details, please refer to Figure 4a and Figure 6 , viewed from the second direction Y, the second end 331 may have a plurality of protrusions 333, for example, the second end 331 may be in a wavy or sawtooth shape but not limited to. Similarly, the first end 131 may also have a plurality of protrusions 133, for example, the first end 131 may be in a wavy or sawtooth shape but not limited to.

[0089] In some embodiments, see Figures 7 to 9a The battery 100 may further include a first layer 60, which may contain an insulating material, and the first layer 60 may also contain a material that can limit ion conduction. The first layer 60 may limit ion conduction, for example, may block or isolate ion conduction. In some embodiments, the insulating material may be, but is not limited to, single-sided adhesive tape or double-sided adhesive tape, in which case the end of the first layer 60 may be prevented from detaching from the surface of 30.

[0090] The first layer 60 adheres to the second end 331 and the second surface 330 and continuously covers the second end 331 and the second surface 330 , thereby suppressing lithium deposition of the battery by suppressing lithium ions generated by the positive electrode active material layer 30 from reaching the opposite negative electrode active material layer 10 .

[0091] In this embodiment, the first layer 60 can also extend from the second surface 330 to the fourth surface 310 to adhere to the fourth surface 310 and cover a portion of the fourth surface 310, further inhibiting the lithium ions generated by the positive electrode active material layer 30 from reaching the negative electrode active material layer 10, thereby avoiding lithium precipitation.

[0092] Preferably, the length of the portion where the first layer 60 is bonded to the fourth surface 310 in the first direction X may be less than or equal to 5 mm, so as to reduce energy density loss while suppressing lithium deposition of the battery.

[0093] In this embodiment, the first layer 60 can also extend from the second end 331 to the second area 30a2 to adhere to the second area 30a2 and cover at least part of the second area 30a2, so as to ensure that the first layer 60 is still adhered to the second end 331 when the edge of the first layer 60 is lifted, thereby further suppressing the lithium deposition phenomenon of the battery. At the same time, when the first layer 60 is made of insulating material, the first layer 60 covering the second area 30a2 can further reduce the probability of short circuit between the positive electrode sheet 30A and the negative electrode sheet 10A. When the first layer 60 extends from the second end 331 to the second area 30a2 and covers the second area 30a2, a fold 65 is formed on the surface of the first layer 60 away from the second end 331. Observed along the second direction Y, the fold 65 is located between the first end 131 and the second end 331.

[0094] Figure 9b It is a partial cross-sectional top view of the battery along the plane where the X direction and the Z direction are located, and the cross section is the positive electrode active material layer 30 and the first layer 60 bonded to the positive electrode active material layer 30. Figure 9b In the embodiment, the distance from one end of the positive electrode active material layer 30 close to the first end 131 to the first end 131 along the first direction X is greater than the distance from the second end 331 to the first end 131 along the first direction X.

[0095] The first layer 60 includes a third end 62 and a fourth end 64 spaced apart and disposed opposite to each other in the first direction X. In the first direction X, the third end 62 is located on a side of the second connection 301 away from the second end 331 , and the fourth end 64 is located on a side of the second connection 301 away from the third end 62 .

[0096] like Figure 7 As shown, when viewed along the second direction Y, the distance from the second end 331 to the third end 62 along the first direction X is a fourth distance F1, and the distance from the second end 331 to the fourth end 64 along the first direction X is a fifth distance F2, wherein F1 is not equal to F2. Preferably, F1 is smaller than F2.

[0097] like Figure 9a and Figure 9b As shown, when viewed from the second direction Y, the width of the first layer 60 along the Z direction is greater than the width of the positive electrode active material layer 30 along the Z direction, which is beneficial to suppressing the lithium deposition phenomenon of the battery. Preferably, the width of the first layer 60 along the Z direction is greater than the width of the positive electrode sheet 30A along the Z direction, and is greater than the width of the negative electrode sheet 10A along the Z direction, which is beneficial to further suppress the lithium deposition phenomenon of the battery, and is also beneficial to further reduce the probability of short circuit between the positive electrode sheet 30A and the negative electrode sheet 10A. In some embodiments, on the basis that the width of the first layer 60 along the Z direction is greater than the width of the positive electrode active material layer 30 along the Z direction, the width of the first layer 60 along the Z direction may be greater than, less than or equal to the width of the negative electrode active material layer 10 along the Z direction.

[0098] In some embodiments, see Fig.10 , the fourth surface 310 may include a third region 310a, a discontinuity region 310b, and a fourth region 310c sequentially connected along the first direction X. Among them, the thickness H1 of the portion of the positive electrode active material layer 30 corresponding to the fourth region 310c in the second direction Y is less than the thickness H2 of the positive electrode active material layer 30 corresponding to the third region 310a. Observed from the second direction Y, the fourth region 310c is located between the discontinuity region 310b and the first connection 101. The first layer 60 covers the fourth region 310c, which is conducive to reducing the influence of the setting of the first layer 60 on the battery thickness, thereby facilitating the improvement of the volume energy density of the battery.

[0099] Preferably, in the second direction Y, a thickness H1 of a portion of the positive electrode active material layer 30 corresponding to the fourth area 310 c in the second direction Y is greater than a height H3 of the discontinuity area 310 b .

[0100] In some embodiments, Fig.10 As shown, the step area 310b is a step surface connecting the third area 310a and the fourth area 310c, which may be an inclined curved surface.

[0101] Preferably, the thickness H4 of the first layer 60 in the second direction Y may be greater than the height H3 of the discontinuity region 310b in the second direction Y. Here, the height of the discontinuity region 310b refers to the distance in the second direction Y from where the discontinuity region 310b connects with the third region 310a to where the discontinuity region 310b connects with the fourth region 310c.

[0102] In some embodiments, the first layer 60 may also cover the discontinuity region 310 b , or cover the discontinuity region 310 b and a portion of the third region 310 a .

[0103] The portion of the first layer 60 located in the fourth region 310c includes a fifth surface 66 that faces away from the fourth region 310c. In some embodiments, the fifth surface 66 includes a portion where the distance G1 from the third region 310a in the second direction Y is greater than the distance G2 from the third surface 110 in the second direction Y.

[0104] In some embodiments, the fourth surface 310 may also be a flat surface.

[0105] In some embodiments, see Fig.11 and Fig.12 The first end 131 can also serve as one end of the negative electrode active material layer 10 close to the starting section of the wound electrode assembly 100A, and at the same time, the second end 331 can serve as one end of the positive electrode active material layer 30 close to the starting section of the wound electrode assembly 100A.

[0106] In the battery of the present application, the thickness of the second part in the second direction gradually decreases from the first connection point toward the first end along the first direction, and the thickness of the fourth part in the second direction gradually decreases from the second connection point toward the second end along the first direction, which is conducive to improving the energy density of the battery; and in the first direction, the first connection point is located between the second connection point and the second end, which is conducive to suppressing the lithium deposition phenomenon of the battery. Therefore, the structure of the battery of the present application is conducive to suppressing the lithium deposition phenomenon while maintaining the energy density of the battery.

[0107] In addition, for ordinary technicians in this field, various other corresponding changes and modifications can be made according to the technical concept of this application, and all these changes and modifications should fall within the protection scope of this application.

Claims

1. A battery, comprising an electrode assembly, wherein the electrode assembly is a wound structure, and the electrode assembly comprises: A negative electrode active material layer, a positive electrode active material layer and a separator located between the positive electrode active material layer and the negative electrode active material layer; wherein, The negative electrode active material layer includes a first portion and a second portion connected to the first portion along a first direction, the second portion includes a first surface and a first end, the first surface is connected to the first portion via a first connection, the first end is away from the first connection and is one end of the negative electrode active material layer, the thickness of the second portion in a second direction perpendicular to the first direction decreases from the first connection toward the first end along the first direction, the main plane of the electrode assembly is the surface of the flat portion of the electrode assembly, the first direction is parallel to the main plane of the electrode assembly, and the second direction is perpendicular to the main plane of the electrode assembly; The positive electrode active material layer includes a third portion and a fourth portion connected to the third portion along the first direction, the fourth portion includes a second surface and a second end, the second surface is connected to the third portion via a second connection, the second end is away from the second connection and is one end of the positive electrode active material layer, and the thickness of the fourth portion in the second direction gradually decreases from the second connection toward the second end along the first direction; The first surface and the second surface are at least partially disposed opposite to each other, and in the first direction, the first connection point is located between the second connection point and the second end; Observed along the second direction, the first end has a first region having a first spacing from the second end in the first direction, and a second region having a second spacing from the second end in the first direction, wherein the first spacing is not equal to the second spacing.

2. The battery according to claim 1, wherein In the first direction, the second end is located between the first connection point and the first end.

3. The battery according to claim 1, wherein The first part includes a third surface, the third part includes a fourth surface, the third surface is connected to the first surface via the first connection, and the fourth surface is connected to the second surface via the second connection; the third surface and the fourth surface are at least partially arranged facing each other.

4. The battery according to claim 3, wherein The third surface and the fourth surface at least partially overlap in the second direction; the first surface and the second surface at least partially overlap in the second direction; The third surface and the second surface at least partially overlap in the second direction.

5. The battery according to claim 4, wherein A distance from the third surface to the fourth surface along the second direction is a first distance, and a distance from the first surface to the second surface along the second direction is a second distance, wherein the first distance is not equal to the second distance.

6. The battery according to claim 5, wherein The first distance is smaller than the second distance.

7. The battery according to claim 5, wherein A distance from the third surface to the second surface along the second direction is a third distance, wherein the third distance is not equal to the first distance.

8. The battery according to claim 7, wherein The third distance is greater than the first distance.

9. The battery according to claim 7, wherein The third distance is not equal to the second distance.

10. The battery according to claim 7, wherein The third distance is smaller than the second distance.

11. The battery according to claim 1, wherein Viewed along the second direction, the second end has a plurality of protrusions.

12. The battery according to claim 3, wherein The battery further includes a first layer, the first layer being bonded to the second end and the second surface and continuously covering the second end and the second surface.

13. The battery according to claim 12, wherein The first layer can block the conduction of ions, and the first layer includes at least one of single-sided adhesive tape or double-sided adhesive tape.

14. The battery according to claim 12, wherein The first layer is also bonded to the fourth surface and covers at least a portion of the fourth surface.

15. The battery according to claim 12, wherein The battery also includes a positive electrode current collector, which is located on the side of the positive electrode active material layer away from the first surface and the third surface, and the positive electrode current collector includes a first area where the positive electrode active material layer is arranged and a second area located on the side of the second end away from the second connection point in the first direction, the positive electrode active material layer is not arranged in the second area, and the first layer is also bonded to the second area and covers at least part of the second area.

16. The battery according to claim 15, wherein The first layer includes a third end and a fourth end arranged opposite to each other in the first direction, and in the first direction, the third end is located on a side of the second connection away from the second end, and the fourth end is located on a side of the second connection away from the third end, wherein, observed along the second direction, the distance from the second end to the third end is a fourth distance, the distance from the second end to the fourth end is a fifth distance, and the fourth distance is not equal to the fifth distance.

17. The battery according to claim 16, wherein The fourth distance is smaller than the fifth distance.

18. The battery according to claim 12, wherein The fourth surface includes a third region, a discontinuity region and a fourth region connected in sequence along the first direction, and the thickness of the portion of the positive electrode active material layer corresponding to the fourth region in the second direction is less than the thickness of the positive electrode active material layer corresponding to the third region; observed from the second direction, the fourth region is located between the discontinuity region and the first connection, and the first layer covers the fourth region.

19. The battery according to claim 18, wherein The thickness of the first layer in the second direction is greater than the height of the discontinuity region in the second direction.

20. The battery according to claim 19, wherein The portion of the first layer located in the fourth region includes a fifth surface, the fifth surface is away from the fourth region, and the fifth surface includes a portion whose distance from the third region in the second direction is greater than the distance from the third surface in the second direction.

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