Battery cell and battery

Abstract

The utility model discloses a battery cell and battery, the battery cell includes: a negative plate including a negative tab and a first main body, the first main body includes a first current collector and a first active material layer, the negative tab is connected to the first current collector, and the first active material layer covers the first current collector; the positive plate and the negative plate are stacked, the positive plate comprises a positive tab, a first supplement layer and a second main body, the second main body comprises a second current collector and a second active material layer, the second current collector comprises a first part and a second part, the two ends of the first part are connected to the positive tab and the second part respectively, and the second part is covered with the second active material layer; the first supplement layer covers the first part, and the projection of the first supplement layer and the projection of the second active material layer fall on the projection of the first active material layer in the thickness direction of the positive plate. The battery cell disclosed by the utility model can have relatively high flatness.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a battery cell and a battery. Background Technology

[0002] In related technologies, batteries include stacked cells and wound cells. The manufacturing process of stacked cells involves cutting positive and negative electrode sheets and separators to specified sizes and then stacking them alternately to form a cell. The manufacturing process of wound cells involves fixing electrode sheets onto a winding needle, and as the winding needle rotates, the positive electrode sheet, negative electrode sheet, and separator are wound into a cell.

[0003] In the case of laminated cells, the amount of active material in the positive electrode is less than that in the negative electrode. Specifically, the size of the positive electrode is smaller than that of the negative electrode. After the positive and negative electrodes are laminated, there is no active material at the head and tail positions of the positive and negative electrodes. When the positive and negative electrodes are hot-pressed, there will be gaps between them, which will result in poor flatness of the laminated cell. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a battery cell that can have a high degree of flatness.

[0005] This utility model also proposes a battery.

[0006] The battery cell according to a first aspect embodiment of the present invention includes:

[0007] A negative electrode sheet includes a negative electrode tab and a first body. The first body includes a first current collector and a first active material layer. The negative electrode tab is connected to the first current collector, and the first active material layer covers the first current collector.

[0008] A positive electrode sheet is stacked with the negative electrode sheet. The positive electrode sheet includes a positive electrode tab, a first supplementary layer, and a second main body. The second main body includes a second current collector and a second active material layer. The second current collector includes a first part and a second part. The two ends of the first part are respectively connected to the positive electrode tab and the second part. The second active material layer covers the second part, and the first supplementary layer covers the first part. Along the thickness direction of the positive electrode sheet, the projections of the first supplementary layer and the second active material layer both fall on the projection of the first active material layer.

[0009] The battery cell according to the embodiments of this utility model has at least the following beneficial effects: the positive electrode includes a first supplementary layer, and the projections of the first supplementary layer and the second active material layer both fall on the projection of the first active material layer. In the prior art, only the second active material layer is provided on the second current collector of the positive electrode, thus creating a gap between the positive and negative electrodes. After hot-pressing the positive and negative electrodes, the flatness of the battery cell is poor. In this application, the projections of the first supplementary layer and the second active material layer both fall on the projection of the first active material layer, that is, the gap between the positive and negative electrodes is filled by the first supplementary layer. Therefore, the flatness of the battery cell can be effectively improved during hot-pressing of the positive and negative electrodes. Specifically, the battery cell can have a high degree of flatness.

[0010] According to some embodiments of the present invention, the second current collector further includes a third part, which is connected to the end of the second part away from the first part. Two first supplementary layers are provided, one of which covers the first part and the other covers the third part.

[0011] According to some embodiments of the present invention, the size of the second current collector is L along the length direction of the positive electrode sheet, and the size of the third part is B, where 0.005≤B / L≤0.008.

[0012] According to some embodiments of the present invention, the size of the second current collector is L along the length direction of the positive electrode sheet, and the size of the first part is A, where 0.005≤A / L≤0.015.

[0013] According to some embodiments of the present invention, the second current collector further includes a third part, which is connected to the end of the second part away from the first part. The first supplementary layer is provided in multiple parts, with a portion of the first supplementary layer covering the first part at intervals along the width direction of the positive electrode sheet, and another portion of the first supplementary layer covering the third part at intervals along the width direction of the positive electrode sheet.

[0014] According to some embodiments of the present invention, in the battery cell, along the width direction of the positive electrode sheet, the size of the second current collector is N, the size of the first supplementary layer is D, and 0.2≤D / N≤0.4.

[0015] According to some embodiments of the present invention, the battery cell has multiple first supplementary layers, which are spaced apart along the width direction of the positive electrode sheet.

[0016] According to some embodiments of the present invention, the positive electrode further includes two second supplementary layers, which cover the second part and are located on both sides of the length direction of the second active material layer.

[0017] According to some embodiments of the present invention, in the battery cell, along the width direction of the positive electrode sheet, the size of the second current collector is M, the size of the second supplementary layer is C, and 0.005≤C / M≤0.008.

[0018] The battery according to the second aspect embodiment of the present invention includes the battery cell described in any one of the first aspect embodiments.

[0019] The battery according to the embodiments of this utility model has at least the following beneficial effects: the positive electrode includes a first supplementary layer, and the projections of the first supplementary layer and the second active material layer both fall on the projection of the first active material layer. In the prior art, only the second active material layer is disposed on the second current collector of the positive electrode, thus creating a gap between the positive and negative electrode. After hot-pressing the positive and negative electrode, the flatness of the cell is poor. However, in this application, the projections of the first supplementary layer and the second active material layer both fall on the projection of the first active material layer, meaning the gap between the positive and negative electrode is filled by the first supplementary layer. Therefore, the flatness of the cell can be effectively improved during hot-pressing of the positive and negative electrode. Specifically, the cell can have a higher flatness. Furthermore, the battery with this cell also has a higher flatness.

[0020] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0022] Figure 1 This is a schematic diagram of the positive electrode plate in the battery cell of the first embodiment of this utility model;

[0023] Figure 2 This is a schematic diagram of a battery cell according to some embodiments of the present invention;

[0024] Figure 3 This is a schematic diagram of the positive electrode plate in the battery cell according to the second embodiment of this utility model;

[0025] Figure 4 This is a schematic diagram of the positive electrode plate in the battery cell according to the third embodiment of this utility model;

[0026] Figure 5 This is a schematic diagram of the negative electrode plate in the battery cell of some embodiments of this utility model.

[0027] Figure label:

[0028] Battery cell 10, negative electrode 100, negative electrode tab 110, first main body 120, first current collector 121, first active material layer 122, positive electrode 200, positive electrode tab 210, first supplementary layer 220, second main body 230, second current collector 231, first part 232, second part 233, third part 234, second active material layer 235, second supplementary layer 236, separator 300. Detailed Implementation

[0029] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0030] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0032] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0033] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0034] The battery can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0035] A battery typically consists of a cell. The cell includes a positive electrode, a negative electrode, and a separator. During charging and discharging, active ions (such as lithium ions) move back and forth between the positive and negative electrodes, inserting and releasing. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0036] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0037] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0038] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0039] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites. Examples of lithium transition metal oxides may include, but are not limited to, at least one of lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also abbreviated as NCM333), LiNi0.5Co0.2Mn0.3O2 (also abbreviated as NCM523), LiNi0.5Co0.25Mn0.25O2 (also abbreviated as NCM211), LiNi0.6Co0.2Mn0.2O2 (also abbreviated as NCM622), LiNi0.8Co0.1Mn0.1O2 (also abbreviated as NCM811), lithium nickel cobalt aluminum oxides (such as LiNi0.85Co0.15Al0.05O2) and their modified compounds.

[0040] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0041] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0042] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0043] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0044] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0045] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0046] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0047] In some implementations, the battery cell also includes an isolation element disposed between the positive and negative terminals.

[0048] In some embodiments, the separator is a separator membrane. The separator membrane can be of various types, and any known porous separator membrane with good chemical and mechanical stability can be selected.

[0049] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0050] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0051] In some embodiments, the battery also includes an electrolyte that acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include an electrolyte salt and a solvent.

[0052] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0053] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0054] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0055] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0056] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0057] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0058] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0059] In some implementations, the battery cell has a wound structure. The positive and negative electrode plates are wound into a wound structure.

[0060] In some implementations, the battery cell has a laminated structure.

[0061] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0062] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0063] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0064] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0065] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0066] In some implementations, the battery cell can be cylindrical, flat, or polygonal, etc.

[0067] In some implementations, the battery cell is provided with tabs that allow current to be drawn out of the cell. The tabs include a positive tab and a negative tab.

[0068] In some embodiments, the battery may include a casing. The casing is used to encapsulate components such as the battery cell and electrolyte. The casing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0069] As an example, the battery can be a cylindrical battery, a prismatic battery, a pouch battery, or a battery of other shapes. Prismatic batteries include, but are not limited to, square-shell batteries, blade-shaped batteries, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0070] The battery mentioned in the embodiments of this application refers to a single physical module that includes one or more batteries to provide higher voltage and capacity.

[0071] In some embodiments, the battery can be a battery module, and when there are multiple batteries, the multiple batteries are arranged and fixed to form a battery module.

[0072] In some embodiments, the battery may be a battery pack, which includes a housing and a battery, with the battery or battery module housed within the housing.

[0073] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0074] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0075] In related technologies, batteries include stacked cells and wound cells. The manufacturing process of stacked cells involves cutting positive and negative electrode sheets and separators to specified sizes and then stacking them alternately to form a cell. The manufacturing process of wound cells involves fixing electrode sheets onto a winding needle, and as the winding needle rotates, the positive electrode sheet, negative electrode sheet, and separator are wound into a cell.

[0076] In the case of laminated battery cells, the amount of active material in the positive electrode is less than that in the negative electrode. Specifically, the size of the positive electrode is smaller than that of the negative electrode. After the positive and negative electrodes are stacked, there is no active material at the head and tail positions of the positive and negative electrodes. When the positive and negative electrodes are hot-pressed, gaps will exist between them, resulting in poor flatness of the laminated battery cell. Specifically, the positive electrode only has active material in the middle, not at the head and tail. Therefore, during hot pressing of the positive and negative electrodes, the uneven stress on the negative electrode leads to poor flatness. To address this issue, this application proposes a battery cell.

[0077] Please refer to Figures 1 to 5In some embodiments, the battery cell 10 includes a negative electrode 100, a positive electrode 200, and a separator 300. The separator 300 is located between the negative electrode 100 and the positive electrode 200. Multiple negative electrode 100s and multiple positive electrode 200s are alternately arranged along the thickness direction of the positive electrode 200. Specifically, the alternating arrangement of multiple negative electrode 100s and multiple positive electrode 200s refers to an arrangement of negative electrode 100-positive electrode 200-negative electrode 100-positive electrode 200. The negative electrode 100 includes a negative electrode tab 110 and a first body 120. The width of the negative electrode tab 110 can be one-tenth or one-fifth of the width of the first current collector 121, etc. The first body 120 includes a first current collector 121 and a first active material layer 122. A negative electrode tab 110 is connected to the first current collector 121, and the first active material layer 122 covers the first current collector 121. A positive electrode 200 and a negative electrode 100 are stacked. The positive electrode 200 includes a positive electrode tab 210, a first supplementary layer 220, and a second body 230. The second body 230 includes a second current collector 231 and a second active material layer 235. The width of the positive electrode tab 210 can be one-tenth or one-fifth of the width of the second current collector 231, etc. The second current collector 231 includes a first portion 232 and a second portion 233. The two ends of the first portion 232 are connected to the positive electrode tab 210 and the second portion 233, respectively. The second active material layer 235 covers the second portion 233, and the first supplementary layer 220 covers the first portion 232. The thickness of the first supplementary layer 220 is equal to the thickness of the second active material layer 235. Along the thickness direction of the positive electrode 200, the projections of the first supplementary layer 220 and the second active material layer 235 both fall on the projection of the first active material layer 122. Specifically, the positive electrode 200 includes a first supplementary layer 220, and the projections of the first supplementary layer 220 and the second active material layer 235 both fall on the projection of the first active material layer 122. In the prior art, only the second active material layer 235 is provided on the second current collector 231 of the positive electrode 200. Therefore, there is a gap between the positive electrode 200 and the negative electrode 100. After hot pressing the positive electrode 200 and the negative electrode 100, the flatness of the cell 10 is poor. In this application, the projections of the first supplementary layer 220 and the second active material layer 235 both fall on the projection of the first active material layer 122. That is, the gap between the positive electrode 200 and the negative electrode 100 is filled by the first supplementary layer 220. This can effectively ensure that the positive electrode 200 is subjected to uniform stress at all positions during hot pressing. Therefore, hot-pressing the positive electrode 200 and the negative electrode 100 can effectively improve the flatness of the battery cell 10. Specifically, the battery cell 10 can have a high degree of flatness.

[0078] Furthermore, the first supplementary layer 220 can specifically be one of insulating ceramic, lithium iron phosphate, or protective adhesive paper. The protective adhesive paper includes a substrate and an adhesive layer. The substrate includes one of thermoplastic polyester, polyethylene, polypropylene, or polyvinyl chloride; the adhesive layer includes one of acrylic resin, polycarbonate, polyurethane, or rubber. In other words, the installation of the first supplementary layer 220 will not affect the normal operation of the battery cell 10.

[0079] Further, please refer to Figures 1 to 5 In some embodiments, the second current collector 231 further includes a third part 234, which is connected to the end of the second part 233 away from the first part 232. Two first supplementary layers 220 are provided: one covering the first part 232 and the other covering the third part 234. Specifically, the first part 232 and the third part 234 are respectively connected to the two ends of the second part 233. The first part 232 is connected to the positive electrode tab 210; that is, the first part 232 can be the head of the second current collector 231, and the third part 234 can be the tail of the second current collector 231. In some cases, the tail of the second current collector 231 does not contain active material. Therefore, by having two first supplementary layers 220 respectively covering the first part 232 and the third part 234, the problem of poor flatness of the battery cell 10 can be effectively solved.

[0080] Further, please refer to Figure 1 In some embodiments, along the length of the positive electrode 200, the size of the second current collector 231 is L, and the size of the third part 234 is B, where 0.005 ≤ B / L ≤ 0.008. The size L of the second current collector 231 along the length of the positive electrode 200 refers to the length of the second current collector 231 being L. The size B of the third part 234 along the length of the positive electrode 200 refers to the width of the third part 234 being B. Specifically, when B / L is less than 0.005, the width of the third part 234 is smaller, and correspondingly, the amount of the second active material layer 235 is larger. This may result in the amount of the second active material layer 235 being no less than the amount of the first active material layer 122, thus causing lithium plating problems. Furthermore, when B / L is less than 0.005, the smaller width of the third part 234 also makes it more difficult to deposit the first supplementary layer 220 on the third part 234. When B / L is greater than 0.008, the width of the third part 234 is larger, and correspondingly, the amount of the second active material layer 235 is smaller, which may result in a lower energy density of the cell 10.

[0081] Further, please refer to Figure 1In some embodiments, along the length of the positive electrode 200, the size of the second current collector 231 is L, and the size of the first part 232 is A, where 0.005 ≤ A / L ≤ 0.015. The size L of the second current collector 231 along the length of the positive electrode 200 refers to the length of the second current collector 231 being L. The size A of the first part 232 along the length of the positive electrode 200 refers to the width of the first part 232 being A. Specifically, when A / L is less than 0.005, the width of the first part 232 is smaller, and correspondingly, the amount of the second active material layer 235 is larger. This may result in the amount of the second active material layer 235 being not less than the amount of the first active material layer 122, thus causing lithium plating problems. Furthermore, when A / L is less than 0.005, the smaller width of the first part 232 also makes it more difficult to deposit the first supplementary layer 220 on the first part 232. When A / L is greater than 0.015, the width of the first part 232 is larger, and correspondingly, the amount of the second active material layer 235 is smaller, which may result in a lower energy density of the cell 10.

[0082] Further, please refer to Figures 1 to 5 In some embodiments, the second current collector 231 further includes a third part 234, which is connected to the end of the second part 233 away from the first part 232. Multiple first supplementary layers 220 are provided, for example, six first supplementary layers 220. A portion of the first supplementary layers 220 are spaced apart along the width direction of the positive electrode 200 and cover the first part 232, for example, three first supplementary layers 220 are spaced apart along the width direction of the positive electrode 200 and cover the first part 232. Another portion of the first supplementary layers 220 are spaced apart along the width direction of the positive electrode 200 and cover the third part 234, for example, three more first supplementary layers 220 are spaced apart along the width direction of the positive electrode 200 and cover the third part 234. With multiple first supplementary layers 220 spaced apart on the second current collector 231, the multiple first supplementary layers 220 can provide support on the first part 232 and on the third part 234, thereby effectively preventing poor flatness of the battery cell 10. Along the length of the positive electrode 200, the first supplementary layer 220 on the first part 232 can be aligned with the first supplementary layer 220 on the third part 234.

[0083] Further, please refer to Figure 4In some embodiments, along the width direction of the positive electrode 200, the size of the second current collector 231 is N, and the size of the first supplementary layer 220 is D, where 0.005 ≤ D / N ≤ 0.008. Specifically, along the width direction of the positive electrode 200, the size of the second current collector 231 being N means that the width of the second current collector 231 is N. Along the width direction of the positive electrode 200, the size of the first supplementary layer 220 means that the length of the first supplementary layer 220 is D. Specifically, when D / N is less than 0.005, the width of the first supplementary layer 220 is smaller, which may result in a smaller area for the first supplementary layer 220 to bear the load, thus leading to poor flatness of the cell 10. When D / N is greater than 0.008, the width of the first supplementary layer 220 is larger, which may result in a smaller amount of the second active material layer 235, potentially leading to a lower energy density of the cell 10.

[0084] Furthermore, in some embodiments, multiple first supplementary layers 220 are provided, spaced apart along the width direction of the positive electrode sheet 200. This spacing effectively prevents poor flatness of the battery cell 10. The spacing of the multiple first supplementary layers 220 can be achieved by having a gap between adjacent first supplementary layers 220, or by having a second active material layer 235 between adjacent first supplementary layers 220. Furthermore, along the thickness direction of the positive electrode sheet 200, the projection of the first supplementary layers 220 can fall on the projections of the positive electrode tab 210 and the negative electrode tab 110, which provides insulation, effectively preventing the positive electrode tab 210 from contacting the negative electrode and causing a short circuit, thus improving the safety of the battery cell 10.

[0085] Further, please refer to Figure 3 In some embodiments, the positive electrode 200 further includes two second supplementary layers 236, the thickness of which is equal to the thickness of the second active material layer 235. The second supplementary layers 236 cover the second portion 233, and the two second supplementary layers 236 are located on opposite sides of the length of the second active material layer 235. Specifically, the arrangement of the first supplementary layer 220 and the second supplementary layer 236 can surround the second active material layer 235; that is, the shape of the second current collector 231 can be rectangular, with the second active material layer 235 located in the middle of the second current collector 231, and the first supplementary layer 220 and the second supplementary layer 236 respectively surrounding and connecting to the edge of the second active material. The arrangement of the second supplementary layer 236 allows for uniform stress distribution at various locations of the second current collector 231 during hot pressing, thereby effectively improving the flatness of the battery.

[0086] Further, please refer to Figure 3In some embodiments, along the width direction of the positive electrode 200, the size of the second current collector 231 is M, and the size of the second supplementary layer 236 is C, where 0.005 ≤ C / M ≤ 0.008. Specifically, along the width direction of the positive electrode 200, the size of the second current collector 231 being M means that the width of the second current collector 231 is M. Along the width direction of the positive electrode 200, the size of the second supplementary layer 236 means that the width of the second supplementary layer 236 is C. Specifically, when C / M is less than 0.005, the width of the second supplementary layer 236 is smaller, and correspondingly, the amount of the second active material layer 235 is larger. This may result in the amount of the second active material layer 235 being not less than the amount of the first active material layer 122, thereby causing lithium plating problems. In addition, when C / M is less than 0.005, it also makes it more difficult to set the second supplementary layer 236 on the second part 233. When C / M is greater than 0.008, the width of the second supplementary layer 236 is larger, and correspondingly, the amount of the second active material layer 235 is smaller, which may result in a lower energy density of the cell 10.

[0087] In some embodiments, the battery includes a cell 10 as described in any of the above embodiments. Specifically, the positive electrode 200 includes a first supplementary layer 220, and the projections of the first supplementary layer 220 and the second active material layer 235 both fall on the projection of the first active material layer 122. In the prior art, only the second active material layer 235 is disposed on the second current collector 231 of the positive electrode 200. Therefore, there is a gap between the positive electrode 200 and the negative electrode 100. After hot-pressing the positive electrode 200 and the negative electrode 100, the flatness of the cell 10 is poor. In this application, the projections of the first supplementary layer 220 and the second active material layer 235 both fall on the projection of the first active material layer 122. That is, the gap between the positive electrode 200 and the negative electrode 100 is filled by the first supplementary layer 220. Therefore, the flatness of the cell 10 can be effectively improved when hot-pressing the positive electrode 200 and the negative electrode 100. Specifically, the cell 10 can have a high degree of flatness. Furthermore, the battery with this cell 10 also has a high degree of flatness.

[0088] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A battery cell, characterized in that, include: A negative electrode sheet includes a negative electrode tab and a first body. The first body includes a first current collector and a first active material layer. The negative electrode tab is connected to the first current collector, and the first active material layer covers the first current collector. A positive electrode sheet is stacked with the negative electrode sheet. The positive electrode sheet includes a positive electrode tab, a first supplementary layer, and a second main body. The second main body includes a second current collector and a second active material layer. The second current collector includes a first part and a second part. The two ends of the first part are respectively connected to the positive electrode tab and the second part. The second active material layer covers the second part, and the first supplementary layer covers the first part. Along the thickness direction of the positive electrode sheet, the projections of the first supplementary layer and the second active material layer both fall on the projection of the first active material layer.

2. The battery cell according to claim 1, characterized in that, The second current collector also includes a third part, which is connected to the end of the second part away from the first part. Two first supplementary layers are provided, one of which covers the first part and the other covers the third part.

3. The battery cell according to claim 2, characterized in that, Along the length of the positive electrode, the size of the second current collector is L, and the size of the third part is B, where 0.005 ≤ B / L ≤ 0.

008.

4. The battery cell according to claim 1, characterized in that, Along the length of the positive electrode, the size of the second current collector is L, and the size of the first part is A, where 0.005 ≤ A / L ≤ 0.

015.

5. The battery cell according to claim 1, characterized in that, The second current collector also includes a third part, which is connected to the end of the second part away from the first part. The first supplementary layer is provided in multiple parts, with a portion of the first supplementary layer covering the first part at intervals along the width direction of the positive electrode sheet, and another portion of the first supplementary layer covering the third part at intervals along the width direction of the positive electrode sheet.

6. The battery cell according to claim 5, characterized in that, Along the width direction of the positive electrode, the size of the second current collector is N, and the size of the first supplementary layer is D, where 0.2 ≤ D / N ≤ 0.

4.

7. The battery cell according to claim 1, characterized in that, Multiple first supplementary layers are provided, and the multiple first supplementary layers are spaced apart along the width direction of the positive electrode sheet.

8. The battery cell according to claim 1, characterized in that, The positive electrode also includes two second supplementary layers, which cover the second part and are located on both sides of the length direction of the second active material layer.

9. The battery cell according to claim 8, characterized in that, Along the width direction of the positive electrode, the size of the second current collector is M, and the size of the second supplementary layer is C, where 0.005≤C / M≤0.

008.

10. A battery, characterized in that, Includes the battery cell as described in any one of claims 1 to 9.

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