Battery cell and battery

Abstract

The battery cell comprises a plurality of straight parts and a plurality of arc parts, the straight parts and the arc parts are alternately arranged in the winding direction of the battery cell, the two ends of each arc part are connected to the two straight parts respectively, and the arc parts are arranged in the winding direction of the battery cell. And at least one through hole is defined by the two adjacent straight parts and the arc part between the two adjacent straight parts. According to the battery cell disclosed by the utility model, lithium precipitation at the corners of the battery cell can be effectively avoided.

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, battery cells include wound structures and stacked structures. A wound structure refers to the process of stacking a positive electrode, a separator, and a negative electrode, and then winding these three components together to form a battery cell. During electrochemical cycling, as lithium ions are inserted and removed, the positive and negative electrodes expand, resulting in uneven stress. This leads to uneven current distribution within the battery cell and the problem of lithium plating at corners. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a battery cell that can effectively prevent lithium plating at the corners of the cell.

[0004] This utility model also proposes a battery.

[0005] According to a first aspect of the present invention, a battery cell includes: a plurality of straight portions and a plurality of arc portions, wherein the straight portions and the arc portions are alternately arranged along the winding direction of the battery cell, and the two ends of the arc portions are respectively connected to two straight portions, and two adjacent straight portions and the arc portion located between two adjacent straight portions together define at least one through hole.

[0006] The battery cell according to the embodiments of this utility model has at least the following beneficial effects: the two ends of the arc portion are respectively connected to two straight portions, and the arc portion is the corner of the battery cell. The two adjacent straight portions and the arc portion located between the two straight portions together define a through hole. After defining the through hole, the area of ​​the arc portion is smaller than that of the arc portion in the prior art. That is, the corner area of ​​the battery cell in this application is smaller, and the stress is also reduced. Thus, the occurrence of lithium plating at the corner of the battery is reduced. Specifically, the battery cell can effectively avoid lithium plating at the corner of the battery cell.

[0007] According to some embodiments of the present invention, the battery cell further includes an adhesive layer, the two ends of which are respectively connected to two adjacent straight portions, and the adhesive layer is attached to the arc portion.

[0008] According to some embodiments of the present invention, the two sides of the arcuate portion of the battery cell are respectively connected to the two adhesive layers.

[0009] According to some embodiments of the present invention, the size of the arc portion along the length direction of the battery cell is L1, and the size of the adhesive layer is L2, where 0.5mm≤L2-L1≤1mm.

[0010] According to some embodiments of the present invention, the cell thickness is 3mm ≤ L1 ≤ 10.5mm.

[0011] According to some embodiments of the present invention, the arcuate portion of the battery cell does not have an active material layer.

[0012] According to some embodiments of the present invention, the battery cell has an active material layer on both the flat portion and the arc portion.

[0013] According to some embodiments of the present invention, the battery cell has two arc-shaped portions between two adjacent straight portions, and the two adjacent straight portions and the two arc-shaped portions located between the two adjacent straight portions together define three through holes.

[0014] According to some embodiments of the present invention, the number of arcuate portions located between two adjacent straight portions in the battery cell is N, where 1 ≤ N ≤ 5.

[0015] 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.

[0016] The battery according to the present invention has at least the following beneficial effects: The two ends of the arc-shaped portion are respectively connected to two straight portions, and the arc-shaped portion is the corner of the battery cell. The two adjacent straight portions and the arc-shaped portion located between the two straight portions together define a through hole. After defining the through hole, the area of ​​the arc-shaped portion is smaller than that of the arc-shaped portion in the prior art. That is, the corner area of ​​the battery cell in this application is smaller, and the stress is reduced, thus reducing the occurrence of lithium plating at the corner of the battery. Specifically, the battery cell can effectively avoid lithium plating at the corner of the battery cell. Furthermore, the battery with this cell has higher safety.

[0017] 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

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0019] Figure 1 This is a schematic diagram of the unfolded battery cell according to the first embodiment of this utility model;

[0020] Figure 2 This is a schematic diagram of a battery cell according to some embodiments of the present invention;

[0021] Figure 3 This is a schematic diagram of the unfolded battery cell according to the second embodiment of this utility model;

[0022] Figure 4 This is a schematic diagram of the unfolded battery cell according to the third embodiment of this utility model;

[0023] Figure 5 This is a schematic diagram of the unfolded battery cell according to the fourth embodiment of this utility model;

[0024] Figure 6 This is a schematic diagram of the unfolded battery cell according to the fifth embodiment of this utility model;

[0025] Figure 7 This is a schematic diagram of the unfolded battery cell according to the sixth embodiment of this utility model;

[0026] Figure 8 This is a partial schematic diagram of a battery cell according to some embodiments of the present invention;

[0027] Figure 9 This is a schematic diagram of the battery cell according to the seventh embodiment of the present invention.

[0028] Figure label:

[0029] 10 cells, 100 flat section, 200 arc section, 300 through hole, 400 adhesive layer, 500 electrode sheet. Detailed Implementation

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.).

[0040] 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 battery positive electrode active materials 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 iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0041] 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.

[0042] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0043] 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.).

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0048] In some implementations, the battery cell also includes an isolation element disposed between the positive and negative terminals.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0056] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0057] As an example, polymer solid electrolytes can be polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0058] 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.

[0059] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0060] In some implementations, the battery cell has a wound structure. The positive and negative electrode plates are wound into a wound structure.

[0061] In some implementations, the battery cell has a laminated structure.

[0062] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0063] 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.

[0064] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0065] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0066] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0067] In some implementations, the battery cell can be cylindrical, flat, or polygonal, etc.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] In related technologies, battery cells include wound structures and stacked structures. A wound structure refers to the stacking of a positive electrode, a separator, and a negative electrode, followed by winding these three components to form a battery cell. During electrochemical cycling, the positive and negative electrode plates expand due to lithium ion insertion / extraction, resulting in uneven stress. This leads to uneven current distribution within the battery cell and the problem of lithium plating at corners. Therefore, this application proposes a battery cell.

[0077] Please refer to Figures 1 to 2 For ease of understanding, Figure 1This diagram illustrates the unfolded state of the battery cell 10. In some embodiments, the battery cell 10 includes a plurality of straight portions 100 and a plurality of arcuate portions 200. The battery cell 10 is formed by winding electrode sheets 500. Specifically, the electrode sheets 500 include positive electrode sheets and negative electrode sheets, which are stacked and then wound to form the battery cell 10. The straight portions 100 refer to the portions where the positive electrode sheets, separator, and negative electrode sheets are wound in a straight shape, and the arcuate portions 200 refer to the portions where the positive electrode sheets, separator, and negative electrode sheets are wound in an arc shape. When unfolded, both the arcuate portions 200 and the straight portions 100 are straight. Along the winding direction of the battery cell 10, the straight portions 100 and the arcuate portions 200 are alternately arranged. That is, after unfolding the battery cell 10, the arrangement of the multiple straight portions 100 and multiple arc portions 200 is as follows: straight portion 100, arc portion 200, straight portion 100, arc portion 200, straight portion 100 (not listed further below). The two ends of the arc portion 200 are respectively connected to two straight portions 100, and the two adjacent straight portions 100 and the arc portion 200 located between the two adjacent straight portions 100 together define at least one through hole 300. Specifically, the two ends of the arc portion 200 are connected to two straight portions 100 respectively. The arc portion 200 is the corner of the cell 10. The two adjacent straight portions 100 and the arc portion 200 located between the two straight portions 100 together define a through hole 300. After defining the through hole 300, the area of ​​the arc portion 200 is smaller than that of the arc portion 200 in the prior art. That is, the corner area of ​​the cell 10 in this application is smaller, and the stress is also reduced. Thus, the occurrence of lithium plating at the corner of the battery is reduced. In particular, the cell 10 can effectively avoid lithium plating at the corner of the cell 10.

[0078] Please refer to Figure 1 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 9The following description continues regarding the phrase "two adjacent straight portions 100 and an arc portion 200 located between the two adjacent straight portions 100 jointly define at least one through hole 300". The shape of the straight portion 100 can be a cuboid, and the shape of the arc portion 200 can be a curved cuboid. In the prior art, when the battery cell 10 is unfolded, the width of the straight portion 100 and the width of the arc portion 200 are equal. However, in this application, when the battery cell 10 is unfolded, the width of the straight portion 100 is greater than the width of the arc portion 200. Therefore, two adjacent straight portions 100 and the arc portion 200 located therein will form at least one through hole 300. The through hole 300 specifically refers to a hole that penetrates through both ends or a hole that penetrates both ends and the edge (in some cases, it can also be called a groove). The aforementioned through hole 300 can be obtained by cutting the electrode 500 after the electrode 500 is formed. Furthermore, multiple arcuate portions 200 can be provided between two adjacent straight portions 100. For example, an arcuate portion 200 is provided between two adjacent straight portions 100. If the arcuate portion 200 is connected at the middle position of the straight portion 100, this can form two through holes 300. For details, please refer to [reference needed]. Figure 3 If the arc portion 200 is connected to the edge of the straight portion 100, this can form a through hole 300, as detailed in the reference. Figure 4 There are two arc-shaped portions 200 between two adjacent straight portions 100. If the arc-shaped portions 200 are connected in the middle of the straight portions 100, this can form three through holes 300. For details, please refer to [reference needed]. Figure 1 If the arc portion 200 is connected to the edge of the straight portion 100, this can form a through hole 300, as detailed in the reference. Figure 5 There are four arc-shaped portions 200 between two adjacent straight portions 100. If the arc-shaped portions 200 are connected in the middle of the straight portions 100, this can form five through holes 300. See the attached document for details. Figure 6 If the arc portion 200 is connected to the edge of the straight portion 100, this can form three through holes 300. See the attached document for details. Figure 7 .

[0079] The following further explains the beneficial effects of the battery of this application. Besides effectively preventing lithium deposition at the "corner" by reducing the arc portion 200, the battery cell 10 of this application can also be modified based on existing winding and coating equipment, reducing equipment and technology costs. That is, equipment used in the prior art for producing wound battery cells 10 can also be applied to the battery cell 10 of this application, and the cost of equipment for producing wound battery cells 10 is lower than the cost of equipment for producing stacked battery cells 10. Furthermore, in addition to cost savings, the design of the through-hole 300 can accommodate more electrolyte, improving the performance of the battery cell 10.

[0080] Furthermore, lithium plating tests were conducted on the battery cell 10 of this application and the battery cell 10 in the prior art, resulting in the following table.

[0081]

[0082] In the table above, Embodiments 1, 2, and 3 are all battery cells 10 of this application, differing only in the number of arc portions 200 between adjacent straight portions 100. Embodiment 4 is a prior art battery cell 10, where the width of the straight portion 100 and the width of the arc portion 200 are equal, thus preventing the formation of through holes 300. The table shows that a higher lithium plating level indicates more severe lithium plating. Compared to prior art battery cells 10, the battery cell 10 of this application effectively avoids lithium plating. Furthermore, the battery cell 10 of this application also exhibits a higher capacity retention rate compared to prior art battery cells 10.

[0083] Further, please refer to Figure 8 In some embodiments, the battery cell 10 further includes an adhesive layer 400, with its two ends connected to two adjacent straight portions 100, and the adhesive layer 400 attached to the arc portion 200. That is, the adhesive layer 400 completely covers the arc portion 200 and extends to the two adjacent straight portions 100. This effectively covers burrs on the arc portion 200, avoiding safety issues caused by burrs generated during cutting. Furthermore, after the adhesive layer 400 is attached to the arc portion 200, it can effectively prevent the arc portion 200 from breaking due to tension.

[0084] Furthermore, to further improve the performance of the battery cell 10, an adhesive layer 400 can be provided on both sides of the arc portion 200 to cover the burrs on both sides of the arc portion 200. For details, please refer to... Figure 8 In some embodiments, the two sides of the arc portion 200 are respectively connected to two adhesive layers 400.

[0085] Further, please refer to Figure 9In some embodiments, along the length of the battery cell 10, the size of the arc portion 200 is L1, and the size of the adhesive layer 400 is L2, where 0.5mm ≤ L2 - L1 ≤ 1mm. Specifically, the amount by which the adhesive layer 400 extends beyond the arc portion 200 along the length of the battery cell 10 can be 0.5mm, 0.6mm, 0.8mm, 0.9mm, or 1mm. This effectively ensures that the adhesive layer 400 covers the arc portion 200. When the amount by which the adhesive layer 400 extends beyond the arc portion 200 along the length of the battery cell 10 is less than 0.5mm, the adhesive layer 400 needs to adhere to the arc portion 200 with high precision, which leads to a decrease in processing efficiency. When the amount by which the adhesive layer 400 extends beyond the arc portion 200 along the length of the battery cell 10 is greater than 1mm, the adhesive layer 400 may cover the arc portion 200, resulting in material waste.

[0086] Furthermore, in some embodiments, 3mm ≤ L1 ≤ 10.5mm. L1 can specifically be 3mm, 4mm, 5mm, 6mm, 8mm, 9mm, 10mm, or 10.5mm. When the dimension of the arc portion 200 along the length of the cell 10 is less than 3mm, the arc portion 200 is easily pulled and broken during winding due to its small size. When the dimension of the arc portion 200 along the length of the cell 10 is greater than 10.5mm, this results in a larger area of ​​the arc portion 200, making it prone to lithium plating when the cell 10 expands.

[0087] Furthermore, in some embodiments, the arcuate portion 200 does not have an active material layer. The arcuate portion 200 can be formed by stacking and winding positive and negative electrode sheets. As mentioned above, an adhesive layer 400 is adhered to the arcuate portion 200. Specifically, the adhesive layer 400 adheres to the active material layer of the positive or negative electrode sheet, thus effectively preventing electrochemical reactions in the active material layer. Since the active material layer on the arcuate portion 200 does not participate in the reaction, an active material layer can be omitted from this part of the positive and negative electrode sheets, thereby reducing material usage and lowering manufacturing costs.

[0088] Furthermore, regarding the aforementioned case where no active material layer is provided on the arc portion 200, in some cases, an active material layer may also be provided on the arc portion 200. Specifically, in some embodiments, active material layers are provided on both the straight portion 100 and the arc portion 200. In the manufacturing process of the battery cell 10, the specific steps may include: first, cutting the positive and negative current collectors, cutting through holes 300 in the positive and negative current collectors, then coating the positive and negative current collectors with active material, then rolling and slitting the positive and negative current collectors, and finally stacking and winding the positive and negative current collectors to form the battery cell 10. In the above manufacturing process, to improve work efficiency, the positive and negative current collectors are coated after cutting. Therefore, active material layers are ultimately provided on both the straight portion 100 and the arc portion 200. If the active material layer on the arc portion 200 is removed after coating, it will increase the number of manufacturing steps and affect the manufacturing efficiency of the cell 10.

[0089] Further, please refer to Figure 1 In some embodiments, two arcuate portions 200 are provided between two adjacent straight portions 100, and the two adjacent straight portions 100 and the two arcuate portions 200 located between the two adjacent straight portions 100 together define three through holes 300. Specifically, the two arcuate portions 200 can both be connected at the middle position of the straight portion 100, so that the two straight portions 100 and the two arcuate portions 200 can form three through holes 300. Among these three through holes 300, two through holes 300 have three openings, and one through hole 300 has two openings. In this arrangement, after the adhesive layer 400 is bonded to the arcuate portion 200, the adhesive layer 400 will not exceed the edge of the electrode 500, and will not result in a low energy density of the cell 10.

[0090] Furthermore, in some embodiments, the number of arcuate portions 200 located between two adjacent straight portions 100 is N, where 1 ≤ N ≤ 5. Specifically, multiple arcuate portions 200 can be provided between two adjacent straight portions 100, for example, the number of arcuate portions 200 can be 1, 2, 3, 4, or 5. To effectively avoid a large contact area at corners, only one arcuate portion 200 needs to be provided between two adjacent straight portions 100. When the number of arcuate portions 200 is greater than 5, the large number of arcuate portions 200 will result in a large contact area at corners, easily leading to lithium plating.

[0091] Furthermore, in some embodiments, a welding groove is provided on the flat portion 100, and the battery cell 10 includes a tab, which is welded to the welding groove, thereby enabling the battery cell 10 to conduct current to the external environment. After the tab is welded to the welding groove, welding burrs can be covered with adhesive tape, which can effectively improve the safety of the battery cell 10.

[0092] In some embodiments, the battery includes a cell 10 as described in any of the above embodiments. The two ends of the arcuate portion 200 are respectively connected to two straight portions 100. The arcuate portion 200 is the corner of the cell 10. The two adjacent straight portions 100 and the arcuate portion 200 located between the two straight portions 100 together define a through hole 300. After defining the through hole 300, the area of ​​the arcuate portion 200 is smaller than that of the arcuate portion 200 in the prior art. That is, the corner area of ​​the cell 10 in this application is smaller, and the stress is reduced, thus reducing the occurrence of lithium plating at the corner of the battery. Specifically, the cell 10 can effectively prevent lithium plating at the corner of the cell 10. Furthermore, the battery having this cell 10 has higher safety.

[0093] 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. An electric cell, characterized by, Comprise: a plurality of flat portions and a plurality of arc portions, the flat portions and the arc portions are arranged alternately along a winding direction of the battery cell, two ends of the arc portion are connected to two flat portions respectively, and two adjacent flat portions and the arc portion between the two adjacent flat portions jointly define at least one through hole.

2. The electric cell of claim 1, wherein, The battery cell further comprises a glue layer, two ends of the glue layer are connected to two adjacent flat portions respectively, and the glue layer is attached to the arc portion.

3. The electric cell of claim 2, wherein, Two sides of the arc portion are connected to two glue layers respectively.

4. The electric cell of claim 2, wherein, Along a length direction of the battery cell, a size of the arc portion is L1, a size of the glue layer is L2, and 0.5mm≤L2-L1≤1mm.

5. The electric cell of claim 4, wherein, 3mm≤L1≤10.5mm.

6. The electric cell of claim 2, wherein, The arc portion is not provided with an active material layer.

7. The electric cell of claim 1, wherein, The flat portion and the arc portion are both provided with an active material layer.

8. The electric cell of claim 1, wherein, Two adjacent flat portions have two arc portions between the two adjacent flat portions, and two adjacent flat portions and two arc portions between the two adjacent flat portions jointly define three through holes.

9. The electric cell of claim 1, wherein, The number of the arc portions between two adjacent flat portions is N, and 1≤N≤5.

10. A battery characterized by The battery cell comprises the battery cell as claimed in any one of claims 1 to 9.

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