Battery cell, battery, electrical apparatus, processing method, and processing device

Abstract

A battery cell, a battery, an electrical apparatus, a processing method, and a processing device, belonging to the technical field of batteries. The battery cell comprises an electrode assembly and an elastic pad. The electrode assembly comprises an electrode sheet and a separator, arranged in a wound manner. The elastic pad is disposed at a winding center of the electrode assembly. The separator comprises a winding portion stacked on the electrode sheet, and an extension part connected to a starting end of the winding portion, the extension part being connected to the elastic pad.

Description

Battery cell, battery, electrical device, processing method and processing equipment Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, an electrical device, a processing method, and processing equipment. Background Art

[0002] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Power batteries consist of several battery cells, but the reliability of these cells needs to be improved.

[0003] Summary of the Invention

[0004] The embodiments of the present application provide a battery cell, a battery, an electrical device, a processing method, and processing equipment, which can improve the reliability of the battery cell.

[0005] In the first aspect, an embodiment of the present application provides a battery cell, comprising: an electrode assembly and an elastic pad, the electrode assembly comprising a pole piece and an isolation membrane arranged in a wound manner, the elastic pad being arranged at the winding center of the electrode assembly, the isolation membrane comprising a winding portion stacked with the pole piece, and an extension portion connected to the starting end of the winding portion, the extension portion being connected to the elastic pad.

[0006] In the above technical solution, when manufacturing a wound electrode assembly, an elastic pad is provided at the center of the winding to replace the original innermost separator, supporting the electrode sheets of the electrode assembly's inner several circles. This increases the curvature radius of the electrode sheets of the inner several circles at the corners, making them less likely to break. This improves problems such as burrs and powder loss caused by breakage, reduces the probability of internal short circuits in the battery cells, and improves the reliability of the battery cells. Furthermore, by providing an elastic pad at the center of the winding to support the electrode sheets of the inner several circles of the electrode assembly, the problem of loose electrode sheets of the inner several circles can be improved, and the gap between the positive and negative electrode sheets of the inner several circles at the corners can be reduced. This reduces the spacing between the positive and negative electrode sheets of the inner several circles at the corners, thereby reducing the risk of lithium plating at the inner circle positions of the corners and improving the reliability and cycle life of the battery cells. Moreover, since the isolation membrane has an extension connected to the elastic pad, it facilitates the winding process of the electrode assembly and the processing and manufacturing of the battery cell. Through the connection between the isolation membrane and the elastic pad, the elastic pad can be more stably supported at the winding center of the electrode assembly, thereby improving the supporting effect of the elastic pad on the pole pieces of several inner circles, and further improving the reliability of the battery cell.

[0007] In some embodiments, the elastic pad is rolled to form the first cushioning structure, and the extension portion is laminated and connected to at least a portion of the elastic pad and rolled together with the elastic pad.

[0008] In the above technical solution, by stacking the extension part and at least part of the elastic pad, the difficulty of connecting the elastic pad and the extension part can be reduced, and the connection reliability of the elastic pad and the extension part can be improved. Since the extension part can be wound together with the elastic pad, continuous processing can be achieved, that is, the process of winding the elastic pad and winding the electrode assembly can be carried out continuously, so that the elastic pad is located at the winding center of the electrode assembly, thereby improving processing efficiency and reducing processing difficulty.

[0009] In some embodiments, the resilient pad is wound at least once.

[0010] In the above technical solution, because the elastic pad is wound at least once, the main body portion is equivalent to having at least two layers of elastic pads in the thickness direction of the electrode assembly, thereby improving the support effect of the main body portion on the electrode assembly. Moreover, the elastic pad wound at least once has rounded corners on both sides, which can support the electrode sheets in the inner circle of the corners in a rounded form. This improves the support effect of the elastic pad on the inner circle of the electrode sheets at the corners, and alleviates the problem of breaking the electrode sheets in the inner circle of the corners and the problem of lithium deposition in the corners.

[0011] In some embodiments, the extension portion is wound inside the elastic pad, and the entire outer circumference of the first buffer structure is wound by the pole piece.

[0012] In the above technical solution, the shape of the elastic pad in the outermost circle can naturally match that of the electrode in the innermost circle, so that the elastic pad can continuously support the electrode in the innermost circle throughout the entire circumference, so that the force applied to the electrode in the innermost circle at all positions throughout the circumference is basically the same. In this way, during the charging and discharging process of the battery cell, the expansion force generated by the expansion of the electrode assembly can be balanced, the stress uniformity of the inner circle electrode can be improved, and the local fracture problem caused by the uneven stress distribution of the inner circle electrode can be improved, thereby improving the reliability of the battery cell.

[0013] In some embodiments, at least a portion of the extension portion is wrapped around the outer circumference of the first buffer structure.

[0014] In the above technical solution, when the entire outer circle of the elastic pad is wound by the extension part, it is beneficial to increase the connection area and connection reliability between the elastic pad and the extension part; and when the outer circle of the elastic pad is partially wound by the extension part, it is beneficial to use the remaining part of the outer circle of the elastic pad to directly support the pole piece, thereby facilitating the elastic pad to support the innermost pole piece.

[0015] In some embodiments, more than half of the outer circumference of the first buffer structure is wound by the pole piece, and the rest of the outer circumference is wound by the extension portion.

[0016] In the above technical solution, since at least a portion of the extension is wound around the outer circumference of the elastic pad, the pole piece and the extension are relay wound around the entire outer circumference of the elastic pad, which facilitates flexible pole piece feeding and facilitates processing. Moreover, the pole piece is wound around more than half of the outer circumference of the elastic pad, and the outer circumferential shape of the elastic pad naturally matches the shape of the innermost pole piece. The elastic pad can provide more effective support for the innermost pole piece over a larger circumference, so that the force applied to each position of the innermost pole piece is basically consistent. In this way, during the charge and discharge process of the battery cell, the expansion force generated by the expansion of the electrode assembly can be balanced, the stress uniformity of the innermost pole piece can be improved, and the problem of local fracture caused by uneven stress distribution of the innermost pole piece can be improved, thereby improving the reliability of the battery cell.

[0017] In some embodiments, the electrode assembly includes a main body and corner portions located at both ends of the main body, and a portion of the extension portion disposed around the outer circumference of the first buffer structure is disposed at one of the corner portions.

[0018] In the above technical solution, the elastic pad can provide more effective support for the innermost pole piece on both sides of the main body and at one of the corners. The innermost pole piece is supported over a larger circumference, thereby further improving the performance of the battery cell.

[0019] In some embodiments, the electrode assembly includes a main body and corner portions located at both ends of the main body, and the winding tail end of the elastic pad is located at the corner portions.

[0020] In the above technical solution, by setting the winding tail end of the elastic pad at the corner, the uneven shape of the elastic pad on both sides of the thickness of the main body can be improved, so that the elastic pad can support the innermost pole piece more evenly on both sides of the thickness of the main body, thereby improving the problem of local stress concentration and cracking of the innermost pole piece at the main body.

[0021] In some embodiments, the rolled tail end of the elastic pad is laminated and connected to the extension portion.

[0022] In the above technical solution, only the end portion of the elastic pad is connected to the extension portion, thereby facilitating the connection between the elastic pad and the extension portion and reducing the difficulty of connecting the two.

[0023] In some embodiments, the overlapping length of the extension portion and the elastic pad is less than or equal to 10 mm.

[0024] In the above technical solution, the material of the extension part is saved, and when the part of the extension part stacked with the elastic pad is wound outside the elastic pad, the length of the outer periphery of the elastic pad wrapped by the extension part can be reduced, so as to lengthen the length of the outer periphery of the elastic pad wrapped by the pole piece, thereby improving the support range of the elastic pad for the innermost pole piece, and meeting the tolerance requirements, and easy to process.

[0025] In some embodiments, the pole piece includes a first pole piece and a second pole piece, the isolation membrane includes a first isolation membrane and a second isolation membrane, the innermost circle of the first pole piece is arranged around the outer periphery of the first buffer structure, the first isolation membrane is isolated between the outer side surface of the first pole piece and the inner side surface of the second pole piece, the second isolation membrane is isolated between the outer side surface of the second pole piece and the inner side surface of the first pole piece, and the extension portion is arranged at the starting end of at least one of the first isolation membrane and the second isolation membrane.

[0026] In the above technical solution, during the winding process of the electrode assembly, the extension part can be used to constrain the innermost circle of the first pole piece, so that the innermost circle shape of the first pole piece is consistent with the outermost circle shape of the elastic pad, so that the elastic pad can reliably support the innermost circle of the pole piece, thereby improving the reliability of the battery cell.

[0027] In some embodiments, the starting ends of the first isolation membrane and the second isolation membrane are both provided with extensions, and the first extension of the starting end of the first isolation membrane and the second extension of the starting end of the second isolation membrane are connected to the same side of the winding tail end of the elastic pad.

[0028] In the above technical solution, the connection is convenient, which is conducive to reducing the processing difficulty and improving the processing efficiency.

[0029] In some embodiments, the starting ends of the first isolation membrane and the second isolation membrane are both provided with extensions, and the first extension of the starting end of the first isolation membrane and the second extension of the starting end of the second isolation membrane are connected to both sides of the winding tail end of the elastic pad.

[0030] The above technical solution is beneficial to improving the connection reliability between each of the first extension portion and the second extension portion and the elastic pad, and improving the reliability of the first isolation diaphragm and the second isolation diaphragm in constraining the innermost circle shape of the first pole piece.

[0031] In some embodiments, the elastic pad is laminated and connected to the extension portion over the entire length of the elastic pad along the winding direction.

[0032] In the above technical solution, the connection reliability between the elastic pad and the extension portion can be improved, the flatness of the inner ring support can be improved, and the wrinkle and misalignment problems of the innermost ring pole piece can be improved.

[0033] In some embodiments, the entire outer circumference of the first buffer structure is surrounded by the extension portion, and the entire outer circumference of the first buffer structure is stacked and connected with the extension portion.

[0034] In the above technical solution, the connection reliability between the elastic pad and the extension portion can be improved.

[0035] In some embodiments, the thickness of the elastic pad is 0.5 mm-1 mm, and the thickness of the first buffer structure is 1 mm-6 mm.

[0036] In the above technical solution, by setting the thickness of the elastic pad to 0.5mm-1mm, the thickness of the first buffer structure formed by winding the elastic pad is 1mm-6mm, so that the first buffer structure can reliably support the electrode assembly, so as to more effectively improve the problem of inner ring electrode breakage or lithium deposition at the corner, and improve the reliability of the battery cell.

[0037] In some embodiments, the inner side and / or outer side of the elastic pad has an adhesive layer.

[0038] In the above technical solution, since the elastic pad is wound, the adhesive layer can be used to bond two adjacent layers of the elastic pad, reducing the gap between the layers of the elastic pad, which is beneficial for subsequently installing the connected elastic pad and electrode assembly into the battery cell shell, that is, facilitating shell insertion. Moreover, since the electrode assembly is wound outside the elastic pad, when the outer side of the elastic pad has an adhesive layer, the adhesive layer can be used to achieve bonding between the innermost circle of the electrode assembly and the outermost circle of the elastic pad, thereby improving the connection stability between the electrode assembly and the elastic pad, and improving the problem of separation of the elastic pad and the electrode assembly after hot pressing of the electrode assembly, thereby forming a gap between the elastic pad and the electrode assembly. This is beneficial for subsequently installing the connected elastic pad and electrode assembly into the battery cell shell, that is, facilitating shell insertion, and is beneficial for improving the support reliability of the elastic pad for the electrode assembly, further reducing the risk of lithium deposition caused by loose inner ring electrode pieces.

[0039] In some embodiments, the elastic pad is in the form of a single piece or a plurality of pieces stacked to form the second buffer structure, and the extension portion is connected to the second buffer structure.

[0040] In the above technical solution, the thickness of the second buffer structure can be controlled more accurately by controlling the number of stacked layers of the elastic pads to meet the required elastic supporting capacity requirements.

[0041] In some embodiments, the extension portion is connected to an outer surface of the second buffer structure in a thickness direction.

[0042] In the above technical solution, the connection between the elastic pad and the extension part can be facilitated, the connection area is large, and the connection reliability is good.

[0043] In some embodiments, at least a portion of the extension portion is sandwiched between two adjacent layers of elastic pads.

[0044] In the above technical solution, the connection between the elastic pad and the extension portion can be more convenient, and the connection is more reliable and stable.

[0045] In some embodiments, the entire outer circumference of the second buffer structure is surrounded by the extension portion, and each side surface of the second buffer structure in the thickness direction is connected to the extension portion over the entire length interval along the winding direction of the extension portion.

[0046] In the above technical solution, the connection reliability between the elastic pad and the extension portion can be improved, the flatness of the inner ring support can be improved, and the wrinkle and misalignment problems of the innermost ring pole piece can be improved.

[0047] In some embodiments, at least half of the outer circumference of the second buffer structure is wound by the pole piece.

[0048] In the above technical solution, since the portion of the pole piece wound around the outer circumference of the second buffer structure exceeds half a circle, the elastic pad can provide more effective support for the innermost pole piece within a larger circumference, thereby improving the performance of the battery cell.

[0049] In a second aspect, an embodiment of the present application further provides a battery comprising a battery cell according to any of the above solutions.

[0050] In the above technical solution, since the reliability of the battery cell according to the embodiment of the present application is improved, it is beneficial to improve the reliability of the battery.

[0051] In a third aspect, an embodiment of the present application further provides an electrical device comprising a battery according to any of the above solutions.

[0052] In the above technical solution, since the reliability of the battery is improved, it is beneficial to improve the working power performance of the electrical device.

[0053] Fourthly, an embodiment of the present application also provides a processing method for processing a battery cell, wherein the battery cell includes an electrode assembly and an elastic pad, the electrode assembly includes a wound electrode sheet and an isolation membrane, the elastic pad is wound at the winding center of the electrode assembly and connected to the isolation membrane; the processing method includes the steps of: connecting the isolation membrane and the elastic pad; winding the elastic pad; feeding the electrode sheet; and winding the electrode assembly.

[0054] In the above technical solution, the processing method allows the elastic pad to be first wound into the winding center of the electrode assembly, replacing the original innermost separator, supporting the electrode sheets of the electrode assembly's inner several circles, thereby increasing the curvature radius of the electrode sheets of the inner several circles at the corners, making them less likely to break, thereby improving problems such as burrs and powder loss caused by breakage, reducing the probability of internal short circuits in the battery cells, and improving the reliability of the battery cells. In addition, by providing an elastic pad at the winding center to support the electrode sheets of the inner several circles of the electrode assembly, the problem of loose electrode sheets of the inner several circles can be improved, and the gap between the positive and negative electrode sheets of the inner several circles at the corners can be reduced, thereby reducing the spacing between the positive and negative electrode sheets of the inner several circles at the corners, thereby reducing the risk of lithium plating at the inner circle position of the corners and improving the reliability and cycle life of the battery cells. Moreover, since the isolation membrane has an extension connected to the elastic pad, it facilitates the winding process of the electrode assembly and the processing and manufacturing of the battery cell. Through the connection between the isolation membrane and the elastic pad, the elastic pad can be more stably supported at the winding center of the electrode assembly, thereby improving the supporting effect of the elastic pad on the pole pieces of several inner circles, and further improving the reliability of the battery cell.

[0055] In some embodiments, the step of connecting the isolation film and the elastic pad specifically includes: connecting the starting end of the isolation film and the winding tail end of the elastic pad.

[0056] In the above technical solution, only the end of the elastic pad is connected to the extension portion, which facilitates the connection of the elastic pad and the extension portion and reduces the difficulty of connecting the two. In addition, the length of the portion where the elastic pad and the extension portion are wound together can be relatively short, thereby shortening the length of the extension portion and saving costs.

[0057] In some embodiments, the step of feeding the pole piece specifically includes: feeding the pole piece when winding to the winding tail end of the elastic pad.

[0058] In the above technical solution, the outer peripheral shape of the elastic pad can naturally match the shape of the innermost circle electrode. The elastic pad can provide more effective support for the innermost circle electrode within a larger circumference, so that the forces at various positions of the innermost circle electrode are basically the same. In this way, during the charging and discharging process of the battery cell, the expansion force generated by the expansion of the electrode assembly can be balanced, the stress uniformity of the inner circle electrode can be improved, and the local fracture problem caused by the uneven stress distribution of the inner circle electrode can be improved, thereby improving the reliability of the battery cell.

[0059] In some embodiments, the step of winding the elastic pad specifically includes: winding the elastic pad at least one turn.

[0060] In the above technical solution, because the elastic pad is wound at least once, the main body portion is equivalent to having at least two layers of elastic pads in the thickness direction of the electrode assembly, thereby improving the support effect of the main body portion on the electrode assembly. Moreover, the elastic pad wound at least once has rounded corners on both sides, which can support the electrode sheets in the inner circles of the corners in a rounded form. This improves the support effect of the elastic pad on the inner circles of the electrode sheets at the corners, thereby improving the problem of breaking the electrode sheets in the inner circles of the corners and the problem of lithium deposition in the corners.

[0061] In some embodiments, after the step of winding the electrode assembly, the step is also included: shaping the electrode assembly so that the electrode assembly is formed into a flat structure and includes a main body and corner portions located at both ends of the main body, and the winding tail end of the elastic pad is located at the corner portion.

[0062] In the above technical solution, by shaping the wound tail end of the elastic pad at the corner, the uneven shape of the elastic pad on both sides of the thickness of the main body can be improved, so that the elastic pad can support the innermost pole piece more evenly on both sides of the thickness of the main body, thereby improving the problem of local stress concentration and cracking of the innermost pole piece at the main body.

[0063] In the fifth aspect, the embodiment of the present application also provides a processing equipment for processing battery cells, the battery cells include electrode assemblies and elastic pads, the electrode assemblies include wound pole pieces and isolation membranes, the elastic pads are wound at the winding center of the electrode assembly and connected to the isolation membrane; the processing equipment includes: a winding tool for winding the elastic pad and the electrode assembly; a connecting tool for connecting the isolation membrane and the elastic pad; a cutting tool for cutting the isolation membrane; the connecting tool, the cutting tool and the winding tool are arranged in sequence along the direction of coil transmission, and the winding tool includes two winding needles with interchangeable positions.

[0064] In the above technical solution, the processing equipment is simple, continuous production can be achieved, and production efficiency can be improved.

[0065] In some embodiments, the connecting tool is a hot pressing tool, which connects the isolation membrane and the elastic pad by thermal bonding.

[0066] In the above technical solution, the connection between the isolation membrane and the elastic pad can be achieved quickly and relatively reliably. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0068] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0069] FIG2 is an exploded view of the structure of a battery provided in some embodiments of the present application;

[0070] FIG3 is a schematic diagram of a battery cell provided in some embodiments of the present application;

[0071] FIG4 is an exploded view of a battery cell provided in some embodiments of the present application;

[0072] FIG5 is a cross-sectional view of an electrode assembly provided in some embodiments of the present application;

[0073] FIG6 is a cross-sectional view of an electrode assembly provided in some other embodiments of the present application;

[0074] FIG7 is a cross-sectional view of an electrode assembly provided in some further embodiments of the present application;

[0075] FIG8 is a schematic diagram of the cooperation between the elastic pad and the isolation membrane provided in some embodiments of the present application;

[0076] FIG9 is a schematic diagram of the cooperation between the elastic pad and the isolation membrane provided in other embodiments of the present application;

[0077] FIG10 is a cross-sectional view of an electrode assembly provided in some embodiments of the present application;

[0078] FIG11 is a cross-sectional view of an electrode assembly provided in some other embodiments of the present application;

[0079] FIG12 is a flow chart of a processing method provided by some embodiments of the present application;

[0080] FIG13 is a flow chart of processing methods provided in other embodiments of the present application;

[0081] FIG14 is a schematic diagram of a processing device provided by some embodiments of the present application;

[0082] FIG15 is a schematic diagram of processing of a curling needle provided in some embodiments of the present application.

[0083] Reference numerals: vehicle 1000; battery 100; controller 200; motor 300; housing 101; first portion 1011; second portion 1012; battery cell 102; first direction F1; second direction F2; third direction F3; housing 1; housing 11; cover 12; accommodating cavity 13; battery cell 2; electrode assembly 3; main body 3a; corner portion 3b; pole piece 31; first pole piece 311; second pole piece 312; separator 3 2; first isolation membrane 321; second isolation membrane 322; winding portion 32a; starting end 32a1 of the winding portion; extension portion 32b; first extension portion 32b1; second extension portion 32b2; elastic pad 4; first buffer structure 41; second buffer structure 42; winding tail end 411; winding head end 412; processing equipment 2000; winding tool 5; winding needle 50; working winding needle 51; preparatory winding needle 52; connecting tool 6; cutting tool 7. DETAILED DESCRIPTION

[0084] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0085] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0086] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0087] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0088] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0089] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0090] The term "plurality" used in this application refers to more than two, including two.

[0091] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0092] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0093] A battery cell includes a housing, a battery cell, and an electrolyte. The battery cell includes at least one electrode assembly. The electrode assembly and the electrolyte are both housed in the housing. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The positive current collector not coated with the positive active material layer protrudes from the positive current collector coated with the positive active material layer. The positive current collector not coated with the positive active material layer serves as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector not coated with the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer. The negative electrode current collector not coated with the negative electrode active material layer serves as the negative electrode tab. The material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon, etc. In order to ensure that a large current can pass through without melting, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together. The material of the isolation membrane can be PP, polypropylene or PE, polyethylene, etc. The electrode assembly mentioned in the embodiment of the present application is a wound structure.

[0094] New energy vehicles have experienced rapid development in recent years. In the electric vehicle sector, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Power batteries consist of several battery cells. When winding the electrode assembly, several turns of separator film are typically wrapped around the inner coil. The separator film is then spaced apart from the positive and negative electrode sheets, and the cells are then wound together and hot-pressed to form the final shape.

[0095] However, due to the thin thickness of the isolation film, the inner ring pole piece is almost unsupported. In the hot pressing and shaping process after winding, the curvature radius of the pole piece of the inner ring at the corner is low, almost folded in half, and easily brittle. In addition, the positive pole piece has a large compactness and high coating quality, which makes it more prone to brittle fracture than the negative pole piece. After brittle fracture, burrs will form and powder will fall off, which can easily cause internal shorts in the battery cell and reduce the reliability of the battery cell. Moreover, the inner ring pole piece is loose. After hot pressing and shaping, the spacing between the positive and negative pole pieces of the inner ring of the corner several layers (such as 1-5 layers) is large, which worsens the charging and discharging at this location, resulting in the problem of lithium plating easily occurring in the inner ring position of the corner, affecting the reliability and cycle life of the battery cell.

[0096] In order to improve the above technical problems, the embodiment of the present application proposes a battery cell. When manufacturing a wound electrode assembly, an elastic pad is set at the center of the winding to replace the original innermost circle isolation film to support the inner circle electrode. In the hot pressing and shaping process after the winding is completed, the curvature radius of the electrode at the inner circle of the corner is increased, which is not easy to break, reducing the problem of burrs and powder loss after breaking, improving the problem of internal short circuit of the battery cell, and improving the reliability of the battery cell. In addition, the problem of loose inner circle electrode can be improved. After hot pressing and shaping, the gap between the inner circle electrode at the corner can be reduced, so that the distance between the positive electrode and the negative electrode at the inner circle position of the corner can be reduced, so as to reduce the risk of lithium plating at the inner circle position of the corner and improve the reliability and cycle life of the battery cell. In addition, according to the battery cell proposed in the embodiment of the present application, the starting end of the isolation membrane is connected to the elastic pad, which facilitates the winding process of the electrode assembly and the processing and manufacturing of the battery cell. Through the connection between the two, the elastic pad can be more stably supported at the winding center of the electrode assembly, thereby improving the support stability of the elastic pad on the inner ring electrode sheet and further improving the reliability of the battery cell.

[0097] The technical solutions described in the embodiments of the present application are applicable to battery cells, batteries containing battery cells, and electrical devices using batteries.

[0098] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0099] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0100] Please refer to FIG1 , which is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application. A battery 100 is disposed inside the vehicle 1000. The battery 100 can be disposed at the bottom, head, or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000.

[0101] The vehicle 1000 may further include a controller 200 and a motor 300 . The controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0102] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0103] Please refer to Figure 2, which is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a battery cell 102 and a box 101 for accommodating the battery cell 102. The box 101 can have various structural forms.

[0104] In some embodiments, the housing 101 may include a first portion 1011 and a second portion 1012, which cover each other and together define a storage space for accommodating the battery cells 102. For example, referring to FIG. 2 , the first portion 1011 and the second portion 1012 may each be a hollow structure with an opening on one side, with the open side of the first portion 1011 covering the open side of the second portion 1012, thereby forming the housing 101 with a storage space. A seal may also be provided between the first portion 1011 and the second portion 1012 to achieve a sealed connection between the first portion 1011 and the second portion 1012. For another example, the second portion 1012 may be a hollow structure with an opening on one side, with the first portion 1011 in the form of a cover that covers the top of the second portion 1012. The first portion 1011 and the second portion 1012 may have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0105] In the battery 100, there can be one or more battery cells 102. If there are multiple battery cells 102, the multiple battery cells 102 can be connected in series, in parallel, or in a hybrid connection. Hybrid connection means that the multiple battery cells 102 are connected both in series and in parallel. The multiple battery cells 102 can be directly connected in series, in parallel, or in a hybrid connection, and then the whole formed by the multiple battery cells 102 is accommodated in the housing 101. Of course, it is also possible that the multiple battery cells 102 are first connected in series, in parallel, or in a hybrid connection to form a battery 100 module, and the multiple battery modules 100 are then connected in series, in parallel, or in a hybrid connection to form a whole and accommodated in the housing 101. In some embodiments, the multiple battery cells 102 can be electrically connected by a busbar to achieve parallel, series, or hybrid connection of the multiple battery cells 102.

[0106] Each battery cell 102 can be a secondary battery 100 or a primary battery 100; it can also be a lithium-sulfur battery 100, a sodium-ion battery 100, or a magnesium-ion battery 100, but is not limited thereto. The battery cell 102 can be cylindrical, flat, or rectangular. For example, in the embodiment shown in FIG3 , the battery cell 102 is a rectangular parallelepiped.

[0107] 3 and 4 , some embodiments of the present application provide a battery cell 102. The battery cell 102 may include a housing 1, a battery cell 2, and an electrolyte. The housing 1 defines a receiving cavity 13, and the battery cell 2 and the electrolyte are both disposed within the receiving cavity 13. The battery cell 2 includes at least one electrode assembly 3. Specifically, the battery cell 2 may include one electrode assembly 3 or multiple electrode assemblies 3. The number of electrode assemblies 3 may be selected based on the capacity requirements of the battery cell 102.

[0108] For example, in conjunction with Figure 4, the shell 1 may include a shell body 11 and a cover plate 12, one end of the shell body 11 has an opening, the electrode assembly 3 is loaded into the shell body 11 through the opening, and the cover plate 12 covers the opening. However, the present application is not limited to this, and the shell 1 may also be in other forms, for example, it may include two half shells that are spliced ​​together, or the shell 1 may also include a sleeve with open ends, and two end covers provided at both ends of the sleeve, etc. It is worth noting that the material of the shell 1 can be a variety of materials, for example, plastic, copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiments of the present application do not impose special restrictions on this. For example, the battery cell 2 includes two electrode assemblies 3, the electrode assembly 3 is a flat, generally rectangular structure, and the two electrode assemblies 3 are stacked along the thickness direction of the battery cell 2, and the shell 1 is a hollow rectangular structure.

[0109] In the embodiment of the present application, referring to Figures 4 and 5 , after winding to obtain the electrode assembly 3, the electrode assembly 3 is hot-pressed and shaped to obtain a flat, generally rectangular parallelepiped electrode assembly 3. Therefore, the electrode assembly 3 may include a flattened main body 3a and corner portions 3b located at both ends of the main body 3a and naturally bent into arcs.

[0110] For example, as shown in Figure 4, before and after hot pressing, the axial direction of the electrode assembly 3 is the first direction F1. After hot pressing, the thickness direction of the electrode assembly 3 is the second direction F2, and the width direction of the electrode assembly 3 is the third direction F3. The first direction F1, the second direction F2, and the third direction F3 are perpendicular to each other. The thickness direction of the main body 3a is the second direction F2, and the corner portions 3b are located at both ends of the main body 3a in the third direction F3. In this way, hot pressing the electrode assembly 3 not only facilitates the installation of the electrode assembly 3 into the housing 1, but also reduces the interlayer gap of the electrode assembly 3 through hot pressing. This allows the number of windings of the electrode assembly 3 to be increased while maintaining the same volume of the housing 13, thereby improving the energy density of the battery cell 102.

[0111] Of course, the present application is not limited to this. For example, in other embodiments of the present application, the winding needle can be designed so that the wound electrode assembly 3 is directly flat and generally rectangular. That is, the shape after winding is consistent with the shape after the aforementioned hot pressing. For simplicity, the following description is based on the example of the electrode assembly 3 that needs to be hot pressed after winding.

[0112] 5 , in the embodiment of the present application, the electrode assembly 3 includes a pole piece 31 and a separator 32, which are stacked and wound together. An elastic pad 4 is provided at the winding center of the electrode assembly 3. The elastic pad 4 is elastic, has a thickness greater than that of the separator 32, and is capable of elastic deformation.

[0113] 5 , in the embodiment of the present application, the separator 32 includes a winding portion 32a stacked with the pole piece 31, and an extension portion 32b connected to the starting end of the winding portion 32a. The extension portion 32b is connected to the elastic pad 4. That is, the separator 32 includes the winding portion 32a and the extension portion 32b. The portion of the separator 32 stacked with the pole piece 31 and wound together is the winding portion 32a. The separator 32 separates the positive pole piece from the negative pole piece in the pole piece 31 through the winding portion 32a. The extension portion 32b connects the starting end of the winding portion 32a to the elastic pad 4.

[0114] Therefore, when manufacturing the wound electrode assembly 3, an elastic pad 4 is provided at the center of the winding to replace the original inner ring separator. This provides support for the electrode sheets 31 of the inner ring of the electrode assembly 3 ("inner ring" refers to at least one ring starting from the innermost ring). This increases the radius of curvature of the electrode sheets 31 of the inner ring of the corner portion 3b, making them less likely to break. This improves problems such as burrs and powder loss caused by breakage, reduces the probability of internal short circuits in the battery cell 102, and improves the reliability of the battery cell 102. Furthermore, by providing the elastic pad 4 at the center of the winding to support the electrode sheets 31 of the inner ring of the electrode assembly 3, the problem of looseness of the electrode sheets 31 of the inner ring of the electrode assembly 3 can be improved. The gap between the positive and negative electrode sheets of the inner ring of the corner portion 3b is reduced, thereby reducing the spacing between the positive and negative electrode sheets of the inner ring of the corner portion 3b, thereby reducing the risk of lithium plating at the inner ring of the corner portion 3b and improving the reliability and cycle life of the battery cell 102. Moreover, since the isolation membrane 32 has an extension portion 32b connected to the elastic pad 4, it facilitates the winding process of the electrode assembly 3 and the processing and manufacturing of the battery cell 102. Through the connection between the isolation membrane 32 and the elastic pad 4, the elastic pad 4 can be more stably supported at the winding center of the electrode assembly 3, thereby improving the supporting effect of the elastic pad 4 on the inner several circles of the pole piece 31, and further improving the reliability of the battery cell 102.

[0115] In some embodiments of the present application, as shown in FIG5 , the elastic pad 4 is wound to form a first buffer structure 41, that is, the first buffer structure 41 is composed of the wound elastic pad 4, and the extension portion 32b is laminated and connected to at least a portion of the elastic pad 4 and is wound together with the elastic pad 4. Thus, by laminating the extension portion 32b with at least a portion of the elastic pad 4, the difficulty of connecting the elastic pad 4 and the extension portion 32b can be reduced, and the reliability of the connection between the elastic pad 4 and the extension portion 32b can be improved. Moreover, since the extension portion 32b can be wound together with the elastic pad 4, continuous processing can be achieved, that is, the process of winding the elastic pad 4 and the winding electrode assembly 3 can be carried out continuously, so that the elastic pad 4 is located at the winding center of the electrode assembly 3, thereby improving processing efficiency and reducing processing difficulty.

[0116] In some embodiments of the present application, as shown in FIG5 , the elastic pad 4 is wound at least one circle. Thus, since the elastic pad 4 is wound at least one circle, in the thickness direction of the electrode assembly 3 (the second direction F2 as shown in FIG5 ), the main body 3a is equivalent to providing at least two layers of elastic pads 4. For example, when the elastic pad 4 is wound one circle, it is equivalent to providing two layers of elastic pads 4 at the main body 3a, and when the elastic pad 4 is wound two circles, it is equivalent to providing four layers of elastic pads 4 at the main body 3a, thereby improving the support effect of the main body 3a on the electrode assembly 3. Moreover, the elastic pad 4 wound at least one circle has rounded corners at both sides of the corner 3b, which can support the pole pieces 31 of the inner circle of the corner 3b on both sides in a rounded form, thereby improving the support effect of the elastic pad 4 on the inner circle of the pole pieces 31 of the inner circle 3b, and improving the problem of breaking the pole pieces 31 of the inner circle of the corner 3b and the problem of lithium deposition at the corner 3b.

[0117] In some embodiments of the present application, as shown in FIG6 , when the elastic pad 4 is wound at least one circle, the extension portion 32 b can be wound inside the elastic pad 4 , and the entire outer circumference of the first buffer structure 41 is wound by the pole piece 31 .

[0118] In the present application, “the outer periphery of the first buffer structure 41 ” refers to the outer peripheral surface of the first buffer structure 41 formed after the elastic pad 4 is rolled up.

[0119] At this time, the shape of the outermost elastic pad 4 and the innermost pole piece 31 can naturally match, so that the elastic pad 4 can continuously support the innermost pole piece 31 throughout the entire circumference, so that the innermost pole piece 31 is subjected to basically the same force at all positions throughout the circumference. In this way, during the charging and discharging process of the battery cell 102, the expansion force generated by the expansion of the electrode assembly 3 can be balanced, the stress uniformity of the inner ring pole piece 31 can be improved, and the local fracture problem caused by the uneven stress distribution of the inner ring pole piece 31 can be improved, thereby improving the reliability of the battery cell 102.

[0120] In some other embodiments of the present application, as shown in FIG. 5 , when the elastic pad 4 is wound at least one circle, at least a portion of the extension portion 32 b may also be wound around the outer periphery of the first buffer structure 41 .

[0121] Exemplarily, the extension portion 32b may be completely wrapped around the outer circumference of the first buffer structure 41, or alternatively, a portion of the extension portion 32b may be wrapped within the elastic pad 4, with the remainder wrapped around the outer circumference of the first buffer structure 41. Exemplarily, if the extension portion 32b is long, the entire outer circumference of the first buffer structure 41 may be wrapped around the extension portion 32b; whereas, if the extension portion 32b is short, the outer circumference of the first buffer structure 41 may be partially wrapped around the extension portion 32b.

[0122] In this way, a flexible connection between the elastic pad 4 and the extension part 32b can be achieved. In addition, when the entire outer circle of the first buffer structure 41 is wrapped by the extension part 32b, it is beneficial to increase the connection area and connection reliability between the elastic pad 4 and the extension part 32b. When the outer circle of the first buffer structure 41 is partially wrapped by the extension part 32b, it is beneficial to use the remaining part of the outer circle of the first buffer structure 41 to directly support the pole piece 31, which is beneficial to the support of the innermost circle pole piece 31 by the elastic pad 4.

[0123] For example, in some embodiments, the pole piece 31 wraps around more than half of the outer circumference of the first buffer structure 41, and the extension portion 32b wraps around the remaining portion of the outer circumference. Thus, since the pole piece 31 wraps around the outer circumference of the first buffer structure 41 for more than half a circle, the extension portion 32b wraps around the outer circumference of the first buffer structure 41 for less than half a circle.

[0124] In the above technical solution, since at least a portion of the extension portion 32b is wound around the outer circumference of the first buffer structure 41, the electrode piece 31 and the extension portion 32b are relay-wound around the outer circumference of the first buffer structure 41. This facilitates flexible feeding of the electrode piece 31 and facilitates processing. Furthermore, since the portion of the electrode piece 31 wound around the outer circumference of the first buffer structure 41 exceeds half a circle, the outer circumferential shape of the first buffer structure 41 naturally matches the shape of the innermost electrode piece 31. The elastic pad 4 can provide relatively effective support for the innermost electrode piece 31 over a large circumference, ensuring that the force applied to each position of the innermost electrode piece 31 is substantially uniform. In this way, during the charge and discharge process of the battery cell 102, the expansion force generated by the expansion of the electrode assembly 3 can be balanced, the stress uniformity of the innermost electrode piece 31 can be improved, and the problem of local fracture caused by uneven stress distribution in the innermost electrode piece 31 can be alleviated, thereby improving the reliability of the battery cell 102.

[0125] Alternatively, when the outer periphery of the first buffer structure 41 is not wound by the pole piece 31, in some embodiments, it can be arranged that the entire outer periphery of the first buffer structure 41 is wound by the extension portion 32b, and the entire outer periphery of the first buffer structure 41 is stacked and connected with the extension portion 32b, thereby improving the connection reliability between the elastic pad 4 and the extension portion 32b.

[0126] In some embodiments of the present application, as shown in FIG5 , when the pole piece 31 wraps around more than half of the outer circumference of the first buffer structure 41, and the extension portion 32b wraps around the rest of the outer circumference, the portion of the extension portion 32b wrapped around the outer circumference of the first buffer structure 41 can be arranged at one of the corner portions 3b. As a result, the elastic pad 4 can provide more effective support for the innermost pole piece 31 on both sides of the main body 3a and at one of the corner portions 3b. This allows the innermost pole piece 31 to be supported over a wider circumference, thereby further improving the performance of the battery cell 102.

[0127] In some embodiments of the present application, as shown in FIG5 , when the elastic pad 4 is wound and wound at least once, the winding tail end 411 of the elastic pad 4 can be positioned at the corner portion 3 b. Thus, by positioning the winding tail end 411 of the elastic pad 4 at the corner portion 3 b, the uneven shape of the elastic pad 4 on both sides of the thickness of the main body portion 3 a can be improved, so that the elastic pad 4 can relatively evenly support the innermost pole piece 31 on both sides of the thickness of the main body portion 3 a, thereby improving the problem of local stress concentration cracking of the innermost pole piece 31 on the main body portion 3 a.

[0128] Specifically, by shaping the winding tail end 411 of the elastic pad 4 at the corner portion 3b, compared to positioning the winding tail end 411 on the main body 3a, the problem of uneven marks on the main body 3a caused by the winding tail end 411 of the elastic pad 4 can be avoided, reducing the risk of wrinkling and lithium deposition on the large surface of the electrode assembly 3, thereby improving the reliability of the battery cell 102. Moreover, the portion of the outermost elastic pad 4 corresponding to the main body 3a is a continuous surface, allowing the portion of the innermost pole piece 31 corresponding to the main body 3a to be well aligned with the outermost elastic pad 4 as a whole, thereby reducing the problem of wrinkling and cracking caused by the formation of stress demarcation points on the large surface of the innermost pole piece 31. There may be a gap between adjacent pole pieces 31 at the corner portion 3b. Setting the relatively protruding position of the wound tail end 411 of the elastic pad 4 at the corner portion 3b is beneficial to further support the pole piece 31 at the corner portion 3b, reduce the gap between adjacent pole pieces 31 at the corner portion 3b, and further help to improve the lithium plating problem at the corner portion 3b.

[0129] In some embodiments of the present application, as shown in FIG5 , when the elastic pad 4 is wound and wound at least once, the winding tail end 411 and the winding head end 412 of the elastic pad 4 can both be disposed at the corner portion 3b. For example, in some examples, as shown in FIG5 and FIG6 , the winding tail end 411 and the winding head end 412 can be disposed at the same corner portion 3b. In other examples, as shown in FIG7 , the winding tail end 411 and the winding head end 412 can be disposed at two corner portions 3b, respectively.

[0130] Therefore, by setting the winding tail end 411 and the winding head end 412 of the elastic pad 4 at the corner part 3b, the uneven shape of the elastic pad 4 on both sides of the thickness of the main body 3a can be further improved, so that the elastic pad 4 can more evenly support the innermost circle of the pole piece 31 on both sides of the thickness of the main body 3a, further improving the problem of local stress concentration cracking of the innermost circle of the pole piece 31 at the main body 3a.

[0131] In some embodiments of the present application, as shown in Figures 5-8, the coiled tail end 411 of the elastic pad 4 is stacked and connected to the extension portion 32b. As a result, only the end of the elastic pad 4 is connected to the extension portion 32b, which facilitates the connection between the elastic pad 4 and the extension portion 32b and reduces the difficulty of connecting the two.

[0132] Exemplarily, the winding tail end 411 of the elastic pad 4 is stacked and connected with the starting end of the extension portion 32b (i.e., the end of the extension portion 32b away from the winding portion 32a), and the length of the part where the elastic pad 4 and the extension portion 32b are wound together can be relatively short, thereby shortening the length of the extension portion 32b and saving costs.

[0133] Exemplarily, the extension portion 32b is entirely laminated and connected to the elastic pad 4. In this case, the portion where the isolation film 32 is laminated and connected to the elastic pad 4 is the extension portion 32b. Furthermore, the extension portion 32b is entirely laminated and connected to the coiled tail end 411 of the elastic pad 4. In this case, the portion where the isolation film 32 is laminated and connected to the coiled tail end 411 of the elastic pad 4 is the extension portion 32b.

[0134] Of course, the extension portion 32b may not only be laminated and connected to the winding tail end 411 of the elastic pad 4. For example, in some other embodiments of the present application, the elastic pad 4 may also be laminated and connected to the extension portion 32b along the entire length of the winding direction, thereby improving the connection reliability between the elastic pad 4 and the extension portion 32b, improving the flatness of the inner ring support, and improving the wrinkling and misalignment problems of the innermost ring pole piece 31. For example, the extension portion 32b may be attached to the outer side and / or inner side of the elastic pad 4 as a whole, and the extension portion 32b is wound simultaneously during the entire process of winding the elastic pad 4.

[0135] In some embodiments of the present application, as shown in Figures 5 and 9, when the winding tail end 411 of the elastic pad 4 is stacked and connected with the extension portion 32b, the overlapping length W of the extension portion 32b and the elastic pad 4 can be less than or equal to 10 mm. This can, on the one hand, save material for the extension portion 32b, and on the other hand, when the portion of the extension portion 32b stacked with the elastic pad 4 is wound outside the elastic pad 4, the length of the outer periphery of the first buffer structure 41 wrapped by the extension portion 32b can be reduced, thereby lengthening the length of the outer periphery of the first buffer structure 41 wrapped by the pole piece 31, thereby increasing the support range of the elastic pad 4 for the innermost pole piece 31. This also meets tolerance requirements and is easy to process.

[0136] In some embodiments of the present application, the length of the extension portion 32b can be less than or equal to 10 mm. This can further save material for the extension portion 32b. When the portion of the extension portion 32b that overlaps the elastic pad 4 is wrapped around the elastic pad 4, the length of the outer periphery of the first buffer structure 41 wrapped by the extension portion 32b can be further reduced, thereby lengthening the length of the outer periphery of the first buffer structure 41 wrapped by the pole piece 31, thereby increasing the support range of the elastic pad 4 for the innermost pole piece 31.

[0137] In some embodiments of the present application, as shown in FIG5 , the electrode 31 includes a first electrode 311 and a second electrode 312, one of which is a positive electrode and the other is a negative electrode. The innermost circle of the first electrode 311 is wound around the outer periphery of the first buffer structure 41, i.e., at least a portion of the outer periphery of the first buffer structure 41 is wound around the first electrode 311. The separator 32 includes a first separator 321 and a second separator 322. The first separator 321 isolates the outer surface of the first electrode 311 from the inner surface of the second electrode 312, while the second separator 322 isolates the outer surface of the second electrode 312 from the inner surface of the first electrode 311. The innermost circle of the first electrode 311 is located between the innermost circle of the first separator 321 and the outermost circle of the elastic pad 4. The two side surfaces of each electrode 31 in the thickness direction are the inner side and the outer side, respectively, with the inner side facing the winding center of the electrode assembly 3 relative to the outer side.

[0138] For example, since the positive electrode plate is more susceptible to brittle fracture than the negative electrode plate, the first electrode plate 311 can be set as the negative electrode plate, and the second electrode plate 312 can be set as the positive electrode plate, so that the innermost circle of the first electrode plate 311 is set inside the innermost circle of the second electrode plate 312, thereby further improving the problem of the inner circle of the positive electrode plate being easily brittle fracture.

[0139] The extension portion 32b is provided at the starting end of at least one of the first isolation film 321 and the second isolation film 322. Specifically, the extension portion 32b is provided at the starting end of at least one of the first isolation film 321 and the second isolation film 322. Thus, during the winding process of the electrode assembly 3, the extension portion 32b can be used to constrain the innermost circle of the first pole piece 311, ensuring that the innermost circle of the first pole piece 311 matches the outermost circle of the elastic pad 4. This allows the elastic pad 4 to reliably support the innermost circle of the pole piece 31, thereby improving the reliability of the battery cell 102.

[0140] Exemplarily, the extension portion 32b includes a first extension portion 32b1 provided at the starting end of the first separator 321 and connected to the elastic pad 4. Thus, the innermost circle of the first electrode piece 311 is located between the innermost circle of the first separator 321 and the outermost circle of the elastic pad 4. Because the first extension portion 32b1 is connected to the elastic pad 4 at the starting end of the first separator 321, during the winding process of the electrode assembly 3, the innermost circle of the first separator 321 can relatively stably constrain the shape of the innermost circle of the first electrode piece 311 to match the outer circumference of the first buffer structure 41, allowing the elastic pad 4 to reliably and stably support the innermost circle of the electrode piece 31, thereby improving the reliability of the battery cell 102.

[0141] Illustratively, the extension portion 32b includes a second extension portion 32b2 provided at the starting end of the second separator 322 and connected to the elastic pad 4. Thus, because the second extension portion 32b2 is connected to the elastic pad 4 at the starting end of the second separator 322, during the winding process of the electrode assembly 3, the innermost circle of the second separator 322 can pass through the innermost circle of the second electrode sheet 312 and the innermost circle of the first separator 321, more reliably constraining the shape of the innermost circle of the first electrode sheet 311 to match the outer circumference of the first buffer structure 41. This allows the elastic pad 4 to reliably and stably support the innermost circle of the electrode sheet 31, thereby improving the reliability of the battery cell 102.

[0142] Exemplarily, the extension portion 32b includes a first extension portion 32b1 located at the starting end of the first separator 321 and connected to the elastic pad 4. Simultaneously, the extension portion 32b includes a second extension portion 32b2 located at the starting end of the second separator 322 and connected to the elastic pad 4. Thus, during the winding process of the electrode assembly 3, the innermost circles of the first separator 321 and the innermost circles of the second separator 322 can both relatively stably constrain the shape of the innermost circle of the first electrode sheet 311 to conform to the outer circumference of the first buffer structure 41, allowing the elastic pad 4 to reliably and stably support the innermost circle of the electrode sheet 31, thereby improving the reliability of the battery cell 102.

[0143] In some embodiments, such as FIG9 , the starting ends of the first isolation membrane 321 and the second isolation membrane 322 are both provided with an extension portion 32b and are located on the same side of the coiled tail end 411 of the elastic pad 4. Specifically, the extension portion 32b includes a first extension portion 32b1 located at the starting end of the first isolation membrane 321 and connected to the elastic pad 4. Simultaneously, the extension portion 32b includes a second extension portion 32b2 located at the starting end of the second isolation membrane 322 and connected to the elastic pad 4. The first extension portion 32b1 and the second extension portion 32b2 can be located on the same side of the coiled tail end 411 of the elastic pad 4. For example, the first extension portion 32b1 and the second extension portion 32b2 can both be connected to the inner side surface of the elastic pad 4 or to the outer side surface of the elastic pad 4, thereby facilitating connection, reducing processing difficulty, and improving processing efficiency.

[0144] In some embodiments, such as FIG8 , the starting ends of both the first and second isolation membranes 321 and 322 are provided with extensions 32b located on opposite sides of the wound end 411 of the elastic pad 4. Specifically, the extensions 32b include a first extension 32b1 located at the starting end of the first isolation membrane 321 and connected to the elastic pad 4, and a second extension 32b2 located at the starting end of the second isolation membrane 322 and connected to the elastic pad 4. The first and second extensions 32b1, 32b2 may be located on either side of the wound end 411 of the elastic pad 4. For example, one of the first and second extensions 32b1, 32b2 may be connected to the inner side of the elastic pad 4, while the other may be connected to the outer side of the elastic pad 4. This improves the reliability of the connection between each of the first and second extensions 32b1, 32b2 and the elastic pad 4, and enhances the reliability of the first and second isolation membranes 321, 322 in constraining the shape of the innermost circle of the first pole piece 311.

[0145] In some embodiments of the present application, the thickness of the elastic pad 4 is 0.5mm-1mm, and the thickness of the first buffer structure 41 is 1mm-6mm. That is, the thickness of a single layer of the elastic pad 4 is 0.5mm-1mm, and the total thickness of the elastic pad 4 after winding is 1mm-6mm.

[0146] Exemplarily, when the elastic pad 4 is wound at least one circle, it is equivalent to setting at least two layers of elastic pads 4 in the thickness direction of the electrode assembly 3 (the second direction F2 as shown in Figure 5). For example, when the elastic pad 4 is wound one circle, combined with Figure 5, it is equivalent to setting two layers of elastic pads 4 in the thickness direction of the electrode assembly 3. At this time, the thickness of the first buffer structure 41 formed by the elastic pad 4 is twice the thickness of the elastic pad 4. When the elastic pad 4 is wound two circles, combined with Figure 6, it is equivalent to setting four layers of elastic pads 4 in the thickness direction of the electrode assembly 3. At this time, the thickness of the first buffer structure 41 formed by the elastic pad 4 is four times the thickness of the elastic pad 4. For example, when the elastic pad 4 is wound one and a half circles, combined with Figure 7, it is equivalent to setting three layers of elastic pads 4 in the thickness direction of the electrode assembly 3. At this time, the thickness of the first buffer structure 41 formed by the elastic pad 4 is three times the thickness of the elastic pad 4, and so on.

[0147] Specifically, if the elastic pad 4 is thin, when the winding needle 50 is pulled out, the elastic pad 4 will be wrinkled, affecting the flatness of the electrode assembly 3. Moreover, if the first buffer structure 41 formed by winding the elastic pad 4 is thin, it cannot play an effective elastic support role, and the inner ring electrode 31 is still prone to breakage, lithium deposition and other problems at the corner position. If the single layer thickness of the elastic pad 4 is large, the deformation variable during winding is large, and it is difficult to control the shape. Moreover, if the first buffer structure 41 formed by winding the elastic pad 4 is large, it occupies more space, affecting the energy density of the electrode assembly 3.

[0148] Through testing, when the thickness of the elastic pad 4 is 0.5mm, the thickness of the first buffer structure 41 formed by the elastic pad 4 is 1mm, and the innermost circle of the pole piece 31 has a slight lithium deposition problem. When the thickness of the elastic pad 4 is 1mm, the thickness of the first buffer structure 41 formed by the elastic pad 4 is 3mm, and the innermost circle of the pole piece 31 has basically no lithium deposition problem. When the thickness of the elastic pad 4 is 1mm, the thickness of the first buffer structure 41 formed by the elastic pad 4 is 6mm, and the innermost circle of the pole piece 31 has basically no lithium deposition problem. When the thickness of the elastic pad 4 is 0.5mm, the thickness of the first buffer structure 41 formed by the elastic pad 4 is 0.5mm, and the innermost circle of the pole piece 31 has a serious lithium deposition problem.

[0149] Therefore, through the above theoretical analysis and testing, it can be seen that by setting the thickness of the elastic pad 4 to 0.5mm-1mm, the thickness of the first buffer structure 41 formed by winding the elastic pad 4 is 1mm-6mm, so that the first buffer structure 41 can reliably support the electrode assembly 3, so as to more effectively improve the lithium plating problem and improve the reliability of the battery cell 102.

[0150] It is worth noting that the material of the elastic pad 4 is not limited. For example, a material whose adsorption force on the electrolyte is smaller than that of the isolation membrane 32 can be selected, such as PE polyethylene, PP polypropylene, PET polyethylene terephthalate, PC polycarbonate, PPS polyphenylene sulfide, glass fiber, carbon fiber and multiple composite materials, which are not limited here.

[0151] In some embodiments of the present application, the inner side (i.e., the surface facing the winding center) and / or the outer side (i.e., the surface away from the winding center) of the elastic pad 4 have an adhesive layer. Thus, since the elastic pad 4 is wound, the adhesive layer can be used to bond two adjacent layers of the elastic pad 4 together, reducing the gaps between the layers of the elastic pad 4. This facilitates the subsequent installation of the connected elastic pad 4 and electrode assembly 3 into the housing 1 of the battery cell 102, thereby facilitating insertion. Moreover, since the electrode assembly 3 is wound around the elastic pad 4, when the outer side of the elastic pad 4 has an adhesive layer, the adhesive layer can be used to achieve bonding between the innermost circle of the electrode assembly 3 and the outermost circle of the elastic pad 4, thereby improving the connection stability between the electrode assembly 3 and the elastic pad 4, improving the problem of separation of the elastic pad 4 and the electrode assembly 3 after the electrode assembly 3 is hot-pressed, and forming a gap between the elastic pad 4 and the electrode assembly 3. This is beneficial for subsequently installing the connected elastic pad 4 and electrode assembly 3 into the housing 1 of the battery cell 102, making it easier to insert the shell, and is beneficial for improving the support reliability of the elastic pad 4 for the electrode assembly 3, further reducing the risk of loosening of the inner ring electrode 31 and causing lithium deposition. It is worth noting that the material of the adhesive layer is not limited, for example, it can be a PVDF polyvinylidene fluoride coating, etc. In this way, during hot pressing, each layer of the elastic pad 4 and the elastic pad 4 and the electrode assembly 3 can be tightly bonded.

[0152] The elastic pad 4 may also be arranged in a non-rolled configuration. For example, in some embodiments of the present application, as shown in FIG10 , the elastic pad 4 may be a single piece or multiple pieces stacked to form the second cushioning structure 42. That is, the second cushioning structure 42 is composed of a single layer or multiple layers of elastic pad 4, and the extension portion 32b is connected to the second cushioning structure 42. In this case, the total thickness of the elastic pad 4 can be more accurately controlled by controlling the number of stacked layers of the elastic pad 4 to meet the required elastic support capacity requirements.

[0153] Exemplarily, when the elastic pad 4 is a single-piece or multi-piece stacked second buffer structure 42, combined with Figure 10, the extension portion 32b can be connected to the two side surfaces on the outer surface in the thickness direction of the second buffer structure 42 (the second direction F2 shown in Figure 10), thereby facilitating the connection between the elastic pad 4 and the extension portion 32b, resulting in a larger connection area and better connection reliability.

[0154] Exemplarily, when the elastic pad 4 is a single-piece or multi-piece stacked second buffer structure 42, combined with Figure 11, the extension portion 32b can also be at least partially sandwiched between two adjacent layers of elastic pads 4, thereby making it easier to connect the elastic pad 4 and the extension portion 32b, and the connection is more reliable and stable.

[0155] In some embodiments of the present application, as shown in Figure 10 , the entire outer circumference of the second buffer structure 42 is surrounded by the extension portion 32b, and each side surface of the second buffer structure 42 in the thickness direction is connected to the extension portion 32b along the entire length of the extension portion 32b along the winding direction. This improves the connection reliability between the elastic pad 4 and the extension portion 32b, improves the flatness of the inner ring support, and alleviates wrinkling and misalignment issues of the innermost pole piece 31.

[0156] In some embodiments of the present application, referring to FIG11 , the pole piece 31 is wound around at least half of the outer circumference of the second buffer structure 42. In the above technical solution, since the portion of the pole piece 31 wound around the outer circumference of the second buffer structure 42 exceeds half a circle, the elastic pad 4 can provide more effective support for the innermost pole piece 31 over a larger circumference, thereby improving the performance of the battery cell 102.

[0157] In some embodiments of the present application, along the axial direction of the electrode assembly 3 (e.g., the first direction F1 shown in FIG. 4 ), the height of the elastic pad 4 is greater than the height of the pole piece 31. Thus, the axial ends of the elastic pad 4 may respectively extend beyond the axial ends of the pole piece 31. For example, the upper end of the elastic pad 4 is higher than the upper end of the pole piece 31, and the lower end of the elastic pad 4 is lower than the lower end of the pole piece 31. In this way, the elastic pad 4 can support the pole piece 31 over the entire axial height of the electrode assembly 3, avoiding problems caused by a portion of the pole piece 31 not being supported by the elastic pad 4, thereby further improving the reliability of the battery cell 102.

[0158] In some embodiments of the present application, the height of the elastic pad 4 is close to the hard height of the electrode assembly 3. It is understood that after the electrode assembly 3 is wound, the portion of the separator 32 that extends beyond the electrode piece 31 will be smoothed, and the height of the electrode assembly 3 after smoothing is the hard height. In some embodiments of the present application, the height of the elastic pad 4 is set to be close to the hard height. For example, the height difference between the two can be within ±2mm. For example, the height of the elastic pad 4 is greater than the hard height, but the height difference is 0-2mm, or the height of the elastic pad 4 is less than the hard height, but the height difference is -2-0mm. For example, the height difference between the height of the elastic pad 4 and the hard height is -2mm, -1.5mm, -1mm, 0mm, 1mm, 1.5mm, 2mm, etc. In this way, on the one hand, the height of the elastic pad 4 can be sufficient to fully support the electrode piece 31 from the entire axial height. On the other hand, it can also avoid the problem that the elastic pad 4 exceeds the hard height too much, resulting in excessive space occupation and affecting the energy density of the battery cell 102.

[0159] In some embodiments of the present application, the elastic pad 4 has pores. The pores can be inherent in the material or machined. Thus, when the elastic pad 4 is squeezed by the expanding electrode assembly 3, it can be compressed and provide an elastic reaction force to the electrode assembly 3. Because the elastic pad 4 supports the innermost electrode sheet 31, the force uniformity of the innermost electrode sheet 31 can be improved. Furthermore, the pores can be used to store electrolyte. Compared to a solid or closed elastic core, the electrolyte injection volume within the housing 1 can be increased, thereby improving the cycle life of the battery cell 102. Furthermore, when the elastic pad 4 is squeezed by the expanding electrode assembly 3, the pores within the elastic pad 4 can be squeezed to expel the electrolyte or gas, causing the elastic pad 4 to be compressed rather than extending along the axial direction of the electrode assembly 3, such as in the first direction F1. Therefore, the axial extension of the elastic pad 4 does not compress the axial side separator 32 of the electrode assembly 3, thereby preventing the positive and negative electrode sheets 31 from being shorted. This further improves the reliability of the battery cell 102.

[0160] For example, if a closed structure such as an airbag were used in place of the elastic pad 4, the airbag's sealed structure would reduce the residual space within the housing 1, leading to a relatively low electrolyte injection rate. Furthermore, when the electrode assembly 3 expands and squeezes the airbag, the airbag, due to its closed structure, would stretch along the axial direction of the electrode assembly 3, squeezing the axial-side separator 32 of the electrode assembly 3 and causing an internal shorting of the electrode piece 31. The elastic pad 4 used in this application, however, has pores that effectively address the aforementioned technical issues.

[0161] This application also provides a battery 100, comprising a battery cell 102 according to any of the above-described solutions. Because the reliability of the battery cell 102 according to the embodiments of this application is improved, this helps improve the reliability of the battery 100. It is worth noting that the battery 100 according to the embodiments of this application may or may not include a housing 101.

[0162] Exemplarily, the battery 100 further includes a busbar component, and at least two of the battery cells 102 are electrically connected via the busbar component. This allows for the series and / or parallel connection of multiple battery cells 102. For example, when multiple battery cells 102 are connected in series, the anode of one battery cell 102 is connected to the cathode of the next battery cell 102 via one busbar component, while the cathode of the battery cell 102 is connected to the anode of the previous battery cell 102 via another busbar component.

[0163] The present application also provides an electrical device comprising a battery 100 according to any of the aforementioned solutions, wherein the battery 100 provides electrical energy to the electrical device. The electrical device may be any of the aforementioned devices or systems employing the battery 100. The improved reliability of the battery 100 facilitates improved performance of the electrical device.

[0164] An embodiment of the present application also provides a processing method for a battery cell 102. Combined with Figures 3-5, the battery cell 102 includes an electrode assembly 3 and an elastic pad 4. The electrode assembly 3 includes a wound electrode sheet 31 and an isolation membrane 32. The elastic pad 4 is wound at the winding center of the electrode assembly 3, and the elastic pad 4 is connected to the isolation membrane 32.

[0165] 12 , the method for processing the battery cell 102 may include the following steps.

[0166] Step S10 connects the isolation film 32 to the elastic pad 4. Exemplarily, the isolation film 32 includes a coiled portion 32a stacked with the electrode 31 and an extension portion 32b connected to the starting end of the coiled portion 32a. At least a portion of the extension portion 32b can be stacked and connected to the inner or outer side of the elastic pad 4. The connection method is not limited, and may include thermal bonding, perforation with a perforated member, or adhesive bonding.

[0167] Step S20 is to wind the elastic pad 4. Since the extension portion 32b is connected to the elastic pad 4, when the elastic pad 4 is wound, the portion of the extension portion 32b that is laminated and connected to the elastic pad 4 can be wound together with the elastic pad 4. For example, the extension portion 32b can be wound inside the elastic pad 4, or the extension portion 32b can be at least partially wound around the outer periphery of the first buffer structure 41.

[0168] Step S30: feeding the electrode 31.

[0169] In step S40 , the electrode assembly 3 is wound, and the elastic pad 4 is disposed at the winding center of the electrode assembly 3 , so that the elastic pad 4 can support the electrode assembly 3 .

[0170] In the above technical solution, this processing method allows the elastic pad 4 to be first wound into the winding center of the electrode assembly 3, replacing the original inner ring separator, and providing support for the electrode sheets 31 of the inner ring of the electrode assembly 3. This increases the curvature radius of the electrode sheets 31 of the inner ring of the corner portion 3b, making them less likely to break. This improves problems such as burrs and powder loss caused by breakage, reduces the probability of internal short circuits in the battery cell 102, and improves the reliability of the battery cell 102. Furthermore, by providing the elastic pad 4 at the winding center to support the electrode sheets 31 of the inner ring of the electrode assembly 3, the problem of looseness of the electrode sheets 31 of the inner ring of the electrode assembly 3 can be improved, and the gap between the positive and negative electrode sheets of the inner ring of the corner portion 3b can be reduced. This reduces the spacing between the positive and negative electrode sheets of the inner ring of the corner portion 3b, thereby reducing the risk of lithium plating in the inner ring of the corner portion 3b and improving the reliability and cycle life of the battery cell 102. Moreover, since the isolation membrane 32 has an extension portion 32b connected to the elastic pad 4, it facilitates the winding process of the electrode assembly 3 and the processing and manufacturing of the battery cell 102. Through the connection between the isolation membrane 32 and the elastic pad 4, the elastic pad 4 can be more stably supported at the winding center of the electrode assembly 3, thereby improving the supporting effect of the elastic pad 4 on the inner several circles of the pole piece 31, and further improving the reliability of the battery cell 102.

[0171] In some embodiments, referring to FIG. 13 , step S10 of connecting the isolation film 32 to the elastic pad 4 specifically includes the following: Step S11 connects the starting end of the isolation film 32 (here, the starting end of the isolation film 32 winding, i.e., the end of the extension 32b away from the winding portion 32a) to the winding tail end 411 of the elastic pad 4. Thus, only the end of the elastic pad 4 is connected to the extension 32b, which facilitates the connection between the elastic pad 4 and the extension 32b and reduces the difficulty of connecting the two. Furthermore, the length of the portion of the elastic pad 4 and the extension 32b that is wound together can be relatively short, thereby shortening the length of the extension 32b and saving costs.

[0172] In some embodiments, with reference to FIG13 , step S30 of feeding the electrode piece 31 specifically includes: step S31 of feeding the electrode piece 31 when winding reaches the winding tail end 411 of the elastic pad 4. This allows the electrode piece 31 to be wound around the outer periphery of the first buffer structure 41, so that more than half of the outer periphery of the first buffer structure 41 can be wound by the electrode piece 31. That is, when the winding of the elastic pad 4 is about to be completed, the electrode piece 31 is promptly fed in so that more than half of the outer periphery of the first buffer structure 41 can be wound by the electrode piece 31. Therefore, the outer peripheral shape of the first buffer structure 41 can naturally match the shape of the innermost pole piece 31, and the elastic pad 4 can play a more effective supporting role for the innermost pole piece 31 within a larger circumference, so that the forces at each position of the innermost pole piece 31 are basically the same. In this way, during the charging and discharging process of the battery cell 102, the expansion force generated by the expansion of the electrode assembly 3 can be balanced, the stress uniformity of the inner ring pole piece 31 can be improved, and the local fracture problem caused by the uneven stress distribution of the inner ring pole piece 31 can be improved, thereby improving the reliability of the battery cell 102.

[0173] In some embodiments, in conjunction with FIG13 , step S20 of winding the elastic pad 4 specifically includes: step S21 of winding the elastic pad 4 at least one turn. In this way, since the elastic pad 4 is wound at least one turn, in the thickness direction of the electrode assembly 3, the main body 3a is equivalent to having at least two layers of elastic pads 4, thereby improving the support effect of the main body 3a on the electrode assembly 3. Moreover, the elastic pad 4 wound at least one turn has rounded corners at the corners 3b on both sides, which can support the pole pieces 31 of the inner circles of the corners 3b on both sides in a rounded form, thereby improving the support effect of the elastic pad 4 on the inner circles of the pole pieces 31 at the corners 3b, thereby improving the problem of breaking the pole pieces 31 of the inner circles of the corners 3b and the problem of lithium deposition at the corners 3b.

[0174] In some embodiments, in combination with Figure 13, after step S40 of winding the electrode assembly 3, the step also includes: step S50 of shaping the electrode assembly 3 so that the electrode assembly 3 is formed into a flat structure and includes a main body 3a and corner portions 3b located at both ends of the main body 3a, and the winding tail end 411 of the elastic pad 4 is located at the corner portion 3b.

[0175] Thus, by shaping the winding tail end 411 of the elastic pad 4 at the corner portion 3b, compared to positioning the winding tail end 411 on the main body portion 3a, the problem of uneven marks on the main body portion 3a caused by the winding tail end 411 of the elastic pad 4 can be avoided, reducing the risk of wrinkling and lithium deposition on the large surface of the electrode assembly 3, thereby improving the reliability of the battery cell 102. Moreover, the portion of the outermost elastic pad 4 corresponding to the main body portion 3a is a continuous surface, allowing the portion of the innermost pole piece 31 corresponding to the main body portion 3a to be well aligned with the outermost elastic pad 4 as a whole, thereby reducing the problem of wrinkling and cracking caused by the formation of stress demarcation points on the large surface of the innermost pole piece 31. There may be a gap between adjacent pole pieces 31 at the corner portion 3b. Setting the relatively protruding position of the wound tail end 411 of the elastic pad 4 at the corner portion 3b is beneficial to further support the pole piece 31 at the corner portion 3b, reduce the gap between adjacent pole pieces 31 at the corner portion 3b, and further help to improve the lithium plating problem at the corner portion 3b.

[0176] In short, by shaping the rolled tail end 411 of the elastic pad 4 at the corner portion 3b, the uneven shape of the elastic pad 4 on both sides of the thickness of the main body 3a can be improved, so that the elastic pad 4 can support the innermost pole piece 31 more evenly on both sides of the thickness of the main body 3a, thereby improving the problem of local stress concentration and cracking of the innermost pole piece 31 at the main body 3a.

[0177] The embodiment of the present application also provides a processing device 2000 for processing a battery cell 102. In conjunction with Figures 3 to 5, the battery cell 102 includes an electrode assembly 3 and an elastic pad 4. The electrode assembly 3 includes a pole piece 31 and an isolation membrane 32 that are wound. The elastic pad 4 is wound at the winding center of the electrode assembly 3, and the elastic pad 4 is connected to the isolation membrane 32. In conjunction with Figure 14, the processing equipment 2000 may include: a winding tool 5, a connecting tool 6, and a cutting tool 7. Among them, the winding tool 5 is used to wind the elastic pad 4 and the electrode assembly 3, the connecting tool 6 is used to connect the isolation membrane 32 and the elastic pad 4, and the cutting tool 7 is used to cut the isolation membrane 32. The connecting tool 6, the cutting tool 7, and the winding tool 5 are arranged in sequence along the coil transmission direction, and the winding tool 5 includes two winding needles 50 that can be interchanged.

[0178] Illustratively, the winding tool 5 includes two winding needles 50 that can be interchanged between a first position and a second position, and the cutting tool 7 and the connecting tool 6 are both located on a side of the first position away from the second position. Illustratively, the winding tool 5 may also include an exchange mechanism or a transmission mechanism for exchanging the positions of the two winding needles 50 so that one winding needle 50 is located in the first position and the other is located in the second position.

[0179] For example, in combination with Figure 14, the winding needle 50 in the first position is defined as the preparatory winding needle 52, and the winding needle 50 in the second position is defined as the working winding needle 51. The first position is above the second position, the connecting tooling 6 and the cutting tooling 7 are both above the first position, and the connecting tooling 6 is above the cutting tooling 7. During continuous production, the working winding needle 51 winds up the previous electrode assembly 3, and the preparatory winding needle 52 prepares to wind up the next electrode assembly 3. Specifically, the isolation membrane 32 wound at the working winding needle 51 can be passed through the preparatory winding needle 52, and the elastic pad 4 can also be passed through the preparatory winding needle 52. The connecting tool 6 is used to connect the isolation membrane 32 and the elastic pad 4, so that a connection point is formed on the isolation membrane 32. The cutting tool 7 is used to cut the isolation membrane 32 below the connection point, and the isolation membrane 32 below the cutting position is wound by the working winding needle 51 until it is separated from the preparatory winding needle 52. At this time, the elastic pad 4 can be wound by the preparatory winding needle 52. Combined with Figure 15, when the elastic pad 4 is wound to the winding tail end 411, the electrode piece 31 can be fed in to wind the electrode assembly 3 outside the elastic pad 4. For example, when the preparatory winding needle 52 starts to wind the elastic pad 4, or after the electrode 31 is fed in, the preparatory winding needle 52 can be moved from the first position to the second position to become the working winding needle 51, and at the same time, the working winding needle 51 moves to the first position to become the preparatory winding needle 52.

[0180] Thus, the processing equipment 2000 is simple, enabling continuous production and improving production efficiency. Furthermore, the battery cells 102 processed by the processing equipment 2000 allow the elastic pad 4 to be first wound into the winding center of the electrode assembly 3, replacing the original inner ring separator. This supports the electrode pieces 31 of the electrode assembly 3 for several turns within the inner ring, thereby increasing the curvature radius of the electrode pieces 31 of the inner ring at the corner portion 3b and making them less prone to breakage. This improves problems such as burrs and powder loss caused by breakage, reduces the probability of internal short circuits in the battery cells 102, and improves the reliability of the battery cells 102. Furthermore, by providing an elastic pad 4 at the winding center to support the electrode sheets 31 of the inner plurality of turns of the electrode assembly 3, the problem of loose electrode sheets 31 of the inner plurality of turns can be improved, and the gap between the positive electrode sheets and the negative electrode sheets of the inner plurality of turns at the corner portion 3b can be reduced. This reduces the spacing between the positive electrode sheets and the negative electrode sheets of the inner plurality of turns at the corner portion 3b, thereby reducing the risk of lithium deposition at the inner plurality of turns at the corner portion 3b and improving the reliability and cycle life of the battery cell 102. Furthermore, because the separator 32 has an extension 32b connected to the elastic pad 4, this facilitates the winding process of the electrode assembly 3 and the processing and manufacturing of the battery cell 102. Furthermore, the connection between the separator 32 and the elastic pad 4 allows the elastic pad 4 to be more stably supported at the winding center of the electrode assembly 3, improving the elastic pad 4's support effect on the electrode sheets 31 of the inner plurality of turns, and further improving the reliability of the battery cell 102.

[0181] In some embodiments, the connecting tool 6 is a hot pressing tool. In this case, the isolation membrane 32 and the elastic pad 4 can be connected by thermal lamination. This allows for a quick and relatively reliable connection between the isolation membrane 32 and the elastic pad 4. Of course, the present application is not limited thereto; for example, the isolation membrane 32 and the elastic pad 4 can also be connected by gluing or other methods.

[0182] 3 to 5 , a battery cell 102 according to a specific embodiment of the present application is described below.

[0183] The battery cell 102 includes: a shell 1, a battery cell 2 and an electrolyte. The shell 1 defines a accommodating cavity 13, and the battery cell 2 and the electrolyte are both arranged in the accommodating cavity 13. The battery cell 2 includes two winding cores, and the winding core includes an electrode assembly 3 and an elastic pad 4. The electrode assembly 3 is flat and includes a main body 3a and corner portions 3b located at both ends of the main body 3a. The electrode assembly 3 includes stacked and wound pole pieces 31 and an isolation membrane 32. The elastic pad 4 is arranged at the winding center of the electrode assembly 3. The elastic pad 4 is wound, and the thickness of the elastic pad 4 is greater than the thickness of the isolation membrane 32. The elastic pad 4 is wound once, and the winding tail end 411 and the winding head end 412 of the elastic pad 4 are both located at the corner portion 3b and are almost spliced ​​together. The surface of the elastic pad 4 has a glue layer.

[0184] The isolation membrane 32 includes a winding portion 32a stacked with the pole piece 31, and an extension portion 32b connected to the starting end of the winding portion 32a. The extension portion 32b is stacked and connected to the winding tail end 411 of the elastic pad 4 and is wound together with the elastic pad 4. The overlapping length of the extension portion 32b and the elastic pad 4 is less than or equal to 10 mm. The extension portion 32b is wound around the periphery of the first buffer structure 41, and the part of the extension portion 32b wound around the periphery of the first buffer structure 41 is located at one of the corner portions 3b. The remaining part of the periphery of the first buffer structure 41 is wound by the pole piece 31.

[0185] Because the elastic pad 4 is wound once, in the thickness direction of the electrode assembly 3 (the second direction F2 shown in FIG5 ), it is equivalent to providing two layers of elastic pads 4, and the two layers of elastic pads 4 have rounded corner transitions. Moreover, after the elastic pad 4 is wound once, that is, after the elastic pad 4 is wound once, the winding tail end 411 and the winding head end 412 of the elastic pad 4 are basically spliced ​​together, such as the gap between the winding tail end 411 and the winding head end 412 does not exceed 1 mm, so that the elastic pad 4 is annular. This can reduce costs, simplify the structure, and avoid the problem of the winding tail end 411 of the elastic pad 4 overlapping the elastic pad 4, causing local protrusion.

[0186] When the pole piece 31 is wound, the innermost pole piece 31 is wound on the outermost elastic pad 4 so that the innermost pole piece 31 extends more than half a circle along the outermost elastic pad 4. In this way, the shapes of the innermost pole piece 31 and the outermost elastic pad 4 can naturally match, so that the elastic pad 4 can continuously support the innermost pole piece 31 within a larger circumference, so that the innermost pole piece 31 is subjected to basically the same force at all positions around the entire circumference. In this way, during the charging and discharging process of the battery cell 102, the expansion force generated by the expansion of the electrode assembly 3 can be balanced, the stress uniformity of the inner circle pole piece 31 can be improved, and the local fracture problem caused by uneven stress distribution of the inner circle pole piece 31 can be improved, thereby improving the reliability of the battery cell 102.

[0187] Furthermore, the electrode 31 is directly supported by the wound elastic pad 4, thereby increasing the curvature of the innermost electrode 31 at the corner position, improving the problem of brittle fracture of the inner electrode 31, resulting in burrs and powder loss, and thus improving the reliability of the battery cell 102. Furthermore, the problem of loose inner electrode 31 can be improved. After hot pressing and shaping, the gap between the inner positive electrode and the negative electrode at the corner 3b of the electrode assembly 3 can be reduced, thereby reducing the risk of lithium plating at the inner position of the corner 3b and improving the reliability and cycle life of the battery cell 102.

[0188] The study found that if a metal mesh-coated insulating layer bracket is used to support the center of the electrode assembly, the shape of this bracket is mostly elliptical, which does not match the shape of the runway-shaped electrode assembly well. The force at each position of the innermost pole piece is uneven. Moreover, the metal mesh has solid areas and mesh areas, and the support effect on the pole piece is inconsistent, which also leads to uneven force at each position of the innermost pole piece. All of these factors can easily cause the innermost pole piece to form a stress demarcation point, which can cause fracture problems at the stress demarcation point. In addition, the metal mesh-coated insulating layer bracket is more complex to manufacture and has higher production costs than the elastic pad formed by winding at least one circle of elastic pad.

[0189] Furthermore, if a hard gasket is used to support the electrode assembly, it lacks elasticity and cannot balance the expansion force generated by the electrode assembly through elastic deformation, thus failing to improve stress uniformity in the inner pole piece. In contrast, the elastic pad 4 in the embodiment of the present application is made of an elastic material and is thicker than the separator 32. Furthermore, it is wound at least once and comprises at least two layers, resulting in greater elasticity and better elastic support for the innermost pole piece 31. This effectively balances the expansion force generated by the expansion of the electrode assembly 3 and improves stress uniformity in the inner pole piece 31.

[0190] In addition, in the embodiment of the present application, when the electrode assembly 3 is manufactured by winding, since several circles of the elastic pad 4 are first wound on the innermost circle, the thickness of the elastic pad 4 is greater than the thickness of the isolation membrane 32. In this way, when the winding is completed and the needle is pulled out, since the elastic pad 4 itself has a certain strength, it is not easy to wrinkle or dislocate, which reduces the risk of unevenness of the electrode assembly 3 caused by the isolation membrane 32 when the innermost circle is the original innermost circle, which is beneficial to improving the flatness of the electrode assembly 3 and improving the reliability of the battery cell 102.

[0191] As shown in Figure 14, when the working winding needle 51 is about to complete winding the previous electrode assembly 3, the preparation winding needle 52 is ready to be replaced. At this time, the separator 32 and the elastic pad 4 can be thermally laminated using the connecting tool 6, so that the separator 32 and the ends of the elastic pad 4 are fixedly connected. The separator 32 is then cut using the cutting tool 7. The working winding needle 51 continues to wind the remaining separator 32, then stops feeding. The preparation winding needle 52 extends to clamp the elastic pad 4, exchanges positions with the working winding needle 51, and begins winding the elastic pad 4. In conjunction with Figure 15, when the elastic pad 4 is about to be wound, the separator 32 can be wound, and the negative and positive electrode sheets can be fed in at the same time to wind the electrode assembly 3. In this way, uninterrupted and continuous production can be achieved. This structure with the elastic pad 4 as the winding center effectively improves production efficiency.

[0192] In this way, it can be wound into a stacked and wound structure consisting of an elastic pad 4, a first electrode sheet 311 (such as a negative electrode sheet), a first isolation film 321, a second electrode sheet 312 (such as a positive electrode sheet) and a second isolation film 322 from the inside to the outside. The elastic pad 4 replaces the original inner circle isolation film, so that there is almost no isolation film 32 between the elastic pad 4 and the innermost circle negative electrode sheet. The innermost circle negative electrode sheet can extend along the elastic pad 4 almost a full circle. In this way, the innermost circle negative electrode sheet naturally matches the outermost circle shape of the elastic pad 4, so that the elastic pad 4 can effectively support the innermost circle negative electrode sheet in almost the entire circle, thereby improving the reliability and cycle life of the battery cell 102, and the electrode assembly 3 is easy to process and has high manufacturing efficiency.

[0193] In the above technical solution, when manufacturing the electrode assembly 3, an elastic pad 4 is wound on the innermost circle to replace the original inner circle isolation film. The thickness of the elastic pad 4 is greater than the thickness of the isolation film 32. In this way, when the winding is completed and the needle is pulled out, since the elastic pad 4 itself has a certain strength, it is not easy to wrinkle or dislocate, which is beneficial to improving the flatness of the electrode assembly 3 and improving the reliability of the battery cell 102. In addition, there is no isolation film 32 between the elastic pad 4 and the innermost circle of the pole piece 31, or there is only a shorter extension 32b of the isolation film 32, so that the innermost circle of the pole piece 31 can extend almost the entire circle along the outermost circle of the elastic pad 4. In this way, the shape of the innermost circle of the pole piece 31 and the outermost circle of the elastic pad 4 can naturally match, so that the elastic pad 4 can effectively support the innermost circle of the pole piece 31 within almost the entire circle. On the one hand, it can balance the expansion force generated by the expansion of the battery cell 102 during the charge and discharge process, improve the stress uniformity of the innermost circle of the pole piece 31, and improve the uneven stress distribution of the innermost circle of the pole piece 31. On the other hand, the problem of local fracture of the innermost circle electrode 31 can be solved, thereby improving the reliability of the battery cell 102; on the other hand, the curvature of the innermost circle electrode 31 can be increased, and the problem of burrs and powder loss caused by the brittle fracture of the innermost circle electrode 31 causing internal short circuit can be improved, thereby improving the reliability of the battery cell 102; on the other hand, the problem of looseness of the innermost circle electrode 31 can be improved. After hot pressing and shaping, the gap between the inner circle electrode 31 at the corner part 3b can be reduced, so that the spacing between the positive electrode and the negative electrode at the inner circle position at the corner part 3b can be reduced, so as to reduce the risk of lithium plating at the inner circle position at the corner part 3b, and improve the reliability and cycle life of the battery cell 102.

[0194] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0195] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, wherein: include: An electrode assembly, comprising a wound electrode sheet and a separator; an elastic pad, provided at the winding center of the electrode assembly; The isolation membrane includes a winding portion stacked with the pole piece, and an extending portion connected to a starting end of the winding portion, and the extending portion is connected to the elastic pad.

2. The battery cell according to claim 1, wherein: The elastic pad is rolled to form a first buffer structure, and the extension portion is laminated and connected to at least a portion of the elastic pad and rolled together with the elastic pad.

3. The battery cell according to claim 2, wherein: The elastic pad is wound at least once.

4. The battery cell according to claim 3, wherein: The extension portion is wound inside the elastic pad, and the entire outer circumference of the first buffer structure is wound by the pole piece.

5. The battery cell according to claim 3, wherein: At least a portion of the extension portion is wrapped around the outer circumference of the first buffer structure. The battery cell according to claim 5 , wherein: More than half of the outer circumference of the first buffer structure is wound by the pole piece, and the remaining part of the outer circumference is wound by the extension portion.

7. The battery cell according to claim 6, wherein: The electrode assembly includes a main body and corner portions located at both ends of the main body, and a portion of the extension portion disposed around the outer circumference of the first buffer structure is disposed at one of the corner portions.

8. The battery cell according to any one of claims 3 to 7, wherein: The electrode assembly includes a main body and corner portions located at both ends of the main body, and the winding tail end of the elastic pad is located at the corner portions.

9. The battery cell according to any one of claims 2 to 8, wherein: The coiled tail end of the elastic pad is connected to the extension portion in a stacked manner.

10. The battery cell according to claim 9, wherein: An overlapping length between the extension portion and the elastic pad is less than or equal to 10 mm.

11. The battery cell according to any one of claims 2 to 10, wherein: The pole piece includes a first pole piece and a second pole piece, and the isolation membrane includes a first isolation membrane and a second isolation membrane. The innermost circle of the first pole piece is arranged around the outer periphery of the first buffer structure. The first isolation membrane is isolated between the outer side surface of the first pole piece and the inner side surface of the second pole piece. The second isolation membrane is isolated between the outer side surface of the second pole piece and the inner side surface of the first pole piece. The extension portion is arranged at the starting end of at least one of the first isolation membrane and the second isolation membrane.

12. The battery cell according to claim 11, wherein: The extension portion is provided at the starting ends of the first isolation membrane and the second isolation membrane, and the first extension portion at the starting end of the first isolation membrane and the second extension portion at the starting end of the second isolation membrane are connected to the same side of the winding tail end of the elastic pad.

13. The battery cell according to claim 11, wherein: The extension portion is provided at the starting ends of the first isolation membrane and the second isolation membrane, and the first extension portion at the starting end of the first isolation membrane and the second extension portion at the starting end of the second isolation membrane are connected to both sides of the winding tail end of the elastic pad.

14. The battery cell according to any one of claims 2 to 8, wherein: The elastic pad is laminated and connected to the extension portion over the entire length along the winding direction.

15. The battery cell according to claim 5, wherein The entire outer circumference of the first buffer structure is wound around by the extension portion, and the entire outer circumference of the first buffer structure is stacked and connected with the extension portion.

16. The battery cell according to any one of claims 2 to 15, wherein: The thickness of the elastic pad is 0.5 mm to 1 mm, and the thickness of the first buffer structure is 1 mm to 6 mm.

17. The battery cell according to any one of claims 2 to 16, wherein: The inner side surface and / or the outer side surface of the elastic pad is provided with a glue layer.

18. The battery cell according to claim 1, wherein The elastic pad is in the form of a single piece or a plurality of pieces stacked to form a second buffer structure, and the extension portion is connected to the second buffer structure.

19. The battery cell according to claim 18, wherein: The extension portion is connected to an outer surface of the second buffer structure in a thickness direction.

20. The battery cell according to claim 18, wherein At least a portion of the extension portion is sandwiched between two adjacent layers of the elastic pads.

21. The battery cell according to any one of claims 18 to 20, wherein: The entire outer circumference of the second buffer structure is surrounded by the extension portion, and each side surface of the second buffer structure in the thickness direction is connected to the extension portion over the entire length interval along the winding direction of the extension portion.

22. The battery cell according to any one of claims 18 to 20, wherein: At least half of the outer circumference of the second buffer structure is wound by the pole piece.

23. A battery, wherein: The invention comprises a battery cell according to any one of claims 1 to 22.

24. An electrical device, wherein: Comprising a battery according to claim 23.

25. A processing method, wherein: Used for processing a battery cell, wherein the battery cell includes an electrode assembly and an elastic pad, the electrode assembly includes a wound electrode sheet and a separator, and the elastic pad is wound at the winding center of the electrode assembly and connected to the separator; The processing method comprises the steps of: connecting the isolation membrane and the elastic pad; winding the elastic pad; feeding the pole piece; The electrode assembly is wound.

26. The processing method according to claim 25, wherein: The step of connecting the isolation membrane and the elastic pad specifically includes: The starting end of the isolation film is connected to the winding tail end of the elastic pad.

27. The processing method according to claim 26, wherein: The step of feeding the electrode specifically includes: The pole piece is fed in when the winding reaches the winding tail end of the elastic pad.

28. The processing method according to any one of claims 25 to 27, wherein: The step of winding the elastic pad specifically includes: Wind the elastic pad at least one turn.

29. The processing method according to claim 28, wherein: After the step of winding the electrode assembly, the method further includes the following steps: The electrode assembly is shaped so that the electrode assembly is formed into a flat structure and includes a main body and corner portions located at both ends of the main body, and the winding tail end of the elastic pad is located at the corner portion.

30. A processing device, wherein: Used for processing a battery cell, wherein the battery cell includes an electrode assembly and an elastic pad, the electrode assembly includes a wound electrode sheet and a separator, and the elastic pad is wound at the winding center of the electrode assembly and connected to the separator; The processing equipment includes: A winding tool, used for winding the elastic pad and the electrode assembly; A connecting tool, used for connecting the isolation membrane and the elastic pad; A cutting tool for cutting the isolation film; The connecting tool, the cutting tool and the winding tool are arranged in sequence along the coil transmission direction, and the winding tool includes two winding needles whose positions can be exchanged.

31. The processing equipment according to claim 30, wherein The connecting tool is a hot pressing tool, which connects the isolation membrane and the elastic pad by thermal bonding.

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