Battery monomer, battery, power utilization device and processing equipment

Abstract

The utility model discloses a battery monomer, a battery, a power utilization device and processing equipment, and belongs to the technical field of batteries. Wherein the battery monomer comprises an electrode assembly and an elastic pad, the electrode assembly comprises a wound pole piece and an isolating membrane, the elastic pad is arranged at the winding center of the electrode assembly, the isolating membrane comprises a winding part and an extension part, the winding part and the pole piece are arranged in a laminated manner, the extension part is connected with the starting end of the winding part, and the extension part is connected with the elastic pad. According to the technical scheme, the elastic pad is arranged at the winding center position of the electrode assembly, so that a plurality of circles of pole pieces on the inner circle of the electrode assembly are supported, and the reliability of the single battery is improved. Moreover, the isolating membrane is provided with the extension part which is connected with the elastic pad, so that the winding processing of the electrode assembly and the processing and manufacturing of the battery monomer are facilitated, and the elastic pad can be more stably supported at the winding center of the electrode assembly through the connection of the isolating membrane and the elastic pad, so that the reliability of the battery monomer is further improved.

Description

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 and a processing equipment. Background Art

[0002] In recent years, new energy vehicles have developed by leaps and bounds. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Among them, power batteries include several battery cells, however, the reliability of battery cells needs to be improved. Utility Model Content

[0003] The embodiments of the present application provide a battery cell, a battery, an electrical device, a processing method and a processing equipment, which can improve the reliability of the battery cell.

[0004] In a 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 a separation membrane arranged in a wound manner, the elastic pad being arranged at the winding center of the electrode assembly, the separation 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.

[0005] In the above technical solution, when manufacturing a wound electrode assembly, an elastic pad is arranged at the center of the winding to replace the original innermost isolation film, and supports the pole pieces of the inner several circles of the electrode assembly, so that the curvature radius of the pole pieces of the inner several circles at the corners is increased, and it is not easy to break, thereby improving the problems of burr and powder shedding caused by breaking, reducing the probability of internal short of the battery cell, and improving the reliability of the battery cell. In addition, by arranging an elastic pad at the center of the winding to support the pole pieces of the inner several circles of the electrode assembly, the problem of loose pole pieces of the inner several circles can be improved, and the gap between the positive pole piece and the negative pole piece of the inner several circles at the corners can be reduced, so that the spacing between the positive pole piece and the negative pole piece of the inner several circles at the corners is reduced, so as to reduce the risk of lithium deposition at the inner circle position at the corners, and improve the reliability and cycle life of the battery cell. 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.

[0006] In some embodiments, the elastic pad is rolled to form the first buffer structure, and the extension portion is laminated and connected to at least a portion of the elastic pad and is rolled together with the elastic pad.

[0007] In the above technical solution, by stacking the extension part and at least part of the elastic pad, the connection difficulty between the elastic pad and the extension part can be reduced and the connection reliability between the elastic pad and the extension part can be improved. Moreover, 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 the processing efficiency and reducing the processing difficulty.

[0008] In some embodiments, the resilient pad is wrapped at least once.

[0009] In the above technical solution, since the elastic pad is wound at least one circle, in the thickness direction of the electrode assembly, the main body is equivalent to setting at least two layers of elastic pads, thereby improving the support effect of the main body on the electrode assembly. Moreover, the elastic pad wound at least one circle has rounded corners at both sides of the corners, which can support the pole pieces of the inner circles of the corners on both sides in a rounded form, improve the support effect of the elastic pad on the inner circles of the pole pieces at the corners, and improve the problem of breaking the inner circles of the pole pieces at the corners and the problem of lithium deposition at the corners.

[0010] 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.

[0011] In the above technical solution, the shape of the elastic pad of the outermost circle can naturally match the shape of the pole piece of the innermost circle, so that the elastic pad can continuously support the pole piece of the innermost circle throughout the entire circumference, so that the force applied to the pole piece of the innermost circle at various 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 pole piece can be improved, and the local fracture problem caused by the uneven stress distribution of the inner circle pole piece can be improved, thereby improving the reliability of the battery cell.

[0012] In some embodiments, at least a portion of the extension portion is wrapped around an outer circumference of the first buffer structure.

[0013] In the above technical solution, when the entire outer circumference 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 circumference of the elastic pad is partially wound by the extension part, it is beneficial to use the rest of the outer circumference of the elastic pad to directly support the pole piece, thereby facilitating the elastic pad to support the innermost pole piece.

[0014] 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.

[0015] In the above technical solution, since at least part of the extension part is wound around the outer circumference of the elastic pad, the pole piece and the extension part are relay wound around the entire circle of the outer circumference of the elastic pad, which is conducive to flexible feeding of the pole piece and convenient processing. Moreover, more than half of the outer circumference of the elastic pad is wound by the pole piece, and the outer circumferential shape of the elastic pad can naturally match the shape of the innermost circle pole piece. The elastic pad can play a more effective supporting role for the innermost circle pole piece within a larger circumference range, so that the force at each position of the innermost circle pole piece 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 innermost circle pole piece can be improved, and the local fracture problem caused by the uneven stress distribution of the innermost circle pole piece can be improved, thereby improving the reliability of the battery cell.

[0016] In some embodiments, the electrode assembly includes a main body and corner portions located at two ends of the main body, and a portion of the extension portion disposed around the outer periphery of the first buffer structure is disposed at one of the corner portions.

[0017] In the above technical solution, the elastic pad can provide more effective support for the innermost pole piece at both sides of the main body and one of the corners, so that the innermost pole piece is supported over a larger circumference, thereby further improving the performance of the battery cell.

[0018] In some embodiments, the electrode assembly includes a main body and corner portions located at two ends of the main body, and the winding tail end of the elastic pad is located at the corner portion.

[0019] 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 cracking of the innermost pole piece at the main body.

[0020] In some embodiments, the rolled tail end of the elastic pad is laminated and connected to the extension portion.

[0021] 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.

[0022] In some embodiments, the overlapping length of the extension portion and the elastic pad is less than or equal to 10 mm.

[0023] 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 wound by the extension part can be reduced, so as to lengthen the length of the outer periphery of the elastic pad wound by the pole piece, thereby improving the support range of the elastic pad to the innermost pole piece, and meeting the tolerance requirements, and easy to realize processing.

[0024] 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.

[0025] In the above technical solution, during the winding process of the electrode assembly, the extension portion 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.

[0026] 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.

[0027] In the above technical solution, the connection is convenient, which is beneficial to reducing the processing difficulty and improving the processing efficiency.

[0028] 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.

[0029] In the above technical solution, it is beneficial to improve the connection reliability between each of the first extension part and the second extension part and the elastic pad, and improve the reliability of the first isolation membrane and the second isolation membrane constraining the innermost circle shape of the first pole piece.

[0030] 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.

[0031] In the above technical solution, the connection reliability between the elastic pad and the extension part 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.

[0032] 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.

[0033] In the above technical solution, the connection reliability between the elastic pad and the extension portion can be improved.

[0034] 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.

[0035] 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 circle pole piece breakage or lithium deposition at the corner, and improve the reliability of the battery cell.

[0036] In some embodiments, the inner side and / or the outer side of the elastic pad has an adhesive layer.

[0037] 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 conducive to the subsequent installation of the connected elastic pad and the electrode assembly into the shell of the battery cell, that is, to facilitate the shell entry. 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 the bonding of 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, improving the problem of separation of the elastic pad and the electrode assembly after hot pressing of the electrode assembly, and forming a gap between the elastic pad and the electrode assembly, which is conducive to the subsequent installation of the connected elastic pad and the electrode assembly into the shell of the battery cell, that is, to facilitate the shell entry, and is conducive to improving the support reliability of the elastic pad to the electrode assembly, and further reducing the risk of lithium deposition caused by loose inner circle pole pieces.

[0038] 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.

[0039] 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.

[0040] In some embodiments, the extension portion is connected to an outer surface of the second buffer structure in a thickness direction.

[0041] 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.

[0042] In some embodiments, at least a portion of the extension portion is sandwiched between two adjacent layers of elastic pads.

[0043] In the above technical solution, the connection between the elastic pad and the extension part can be more convenient, and the connection is more reliable and stable.

[0044] In some embodiments, the entire outer circumference of the second buffer structure is surrounded by the extension portion, and each side surface in the thickness direction of the second buffer structure is connected to the extension portion over the entire length interval along the winding direction of the extension portion.

[0045] In the above technical solution, the connection reliability between the elastic pad and the extension part 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.

[0046] In some embodiments, at least half of the outer circumference of the second buffer structure is wound by the pole piece.

[0047] In the above technical solution, since the pole piece is wound around the outer circumference of the second buffer structure for more than 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.

[0048] In a second aspect, an embodiment of the present application further provides a battery, comprising a battery cell of any of the above-mentioned solutions.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] In the fourth aspect, the embodiments of the present application also provide a processing equipment 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 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 coil transmission direction, and the winding tool includes two winding needles with interchangeable positions.

[0053] In the above technical solution, the processing equipment is simple, continuous production can be achieved, and production efficiency can be improved.

[0054] In some embodiments, the connecting tool is a hot pressing tool, which connects the isolation membrane and the elastic pad by thermal bonding.

[0055] 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

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. 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 related drawings can be obtained based on these drawings without paying creative work.

[0057] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0058] Figure 2 An exploded view of the structure of a battery provided in some embodiments of the present application;

[0059] Figure 3 A schematic diagram of a battery cell provided for some embodiments of the present application;

[0060] Figure 4 An exploded view of a battery cell provided for some embodiments of the present application;

[0061] Figure 5 A cross-sectional view of an electrode assembly provided in some embodiments of the present application;

[0062] Figure 6 A cross-sectional view of an electrode assembly provided in some other embodiments of the present application;

[0063] Figure 7 A cross-sectional view of an electrode assembly provided in some further embodiments of the present application;

[0064] Figure 8 A schematic diagram of the coordination between the elastic pad and the isolation membrane provided in some embodiments of the present application;

[0065] Fig. 9 A schematic diagram of the coordination between the elastic pad and the isolation membrane provided in other embodiments of the present application;

[0066] Fig.10 A cross-sectional view of an electrode assembly provided in some embodiments of the present application;

[0067] Fig.11 A cross-sectional view of an electrode assembly provided in some other embodiments of the present application;

[0068] Fig.12 A flowchart of a processing method provided for some embodiments of the present application;

[0069] Fig.13 Flow charts of processing methods provided for other embodiments of the present application;

[0070] Fig.14 A processing schematic diagram of a processing device provided for some embodiments of the present application;

[0071] Fig.15 A schematic diagram of the processing of the curling needle provided in some embodiments of the present application.

[0072] Reference numerals: vehicle 1000; battery 100; controller 200; motor 300; housing 101; first part 1011; second part 1012; battery cell 102; first direction F1; second direction F2; third direction F3; housing 1; housing body 11; cover plate 12; accommodating cavity 13; battery cell 2; electrode assembly 3; main body 3a; corner part 3b; pole piece 31; first pole piece 311; second pole piece 312; isolation film 3 2; first isolation film 321; second isolation film 322; winding portion 32a; starting end 32a1 of 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

[0073] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0074] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. 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 and secondary relationship.

[0075] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0076] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0077] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0078] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0079] The term "plurality" used in the present application refers to more than two, including two.

[0080] In the present 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 the present application do not limit this. Battery cells may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application do not limit this.

[0081] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery module or a battery pack. The battery generally includes a box for encapsulating one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0082] A battery cell includes a shell, a battery cell and an electrolyte. The battery cell includes at least one electrode assembly. The electrode assembly and the electrolyte are both contained in the shell. The electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. The battery cell mainly works by the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode collector. The positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer. The positive electrode collector not coated with the positive electrode active material layer serves as a positive electrode ear. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode 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 a negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon or silicon, etc. In order to ensure that a large current passes 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 film may be PP, polypropylene or PE, polyethylene, etc. The electrode assembly mentioned in the embodiment of the present application is a winding structure.

[0083] In recent years, new energy vehicles have developed by leaps and bounds. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Among them, the power battery includes a number of battery cells. When the battery cells are wound into electrode assemblies, the inner circle is usually rolled into a few circles of separators, and then the separators and the positive and negative pole pieces are placed at intervals, and then rolled together and hot pressed and shaped.

[0084] However, due to the thin thickness of the isolation film, the inner circle pole piece is almost unsupported. In the hot pressing shaping process after winding, the curvature radius of the pole piece in the inner circle at the corner is low, almost folded in half, and easy to break. In addition, the positive pole piece has a large compactness and high coating quality, which is more likely to break than the negative pole piece. After breaking, 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. In addition, the inner circle pole piece is loose. After hot pressing shaping, the spacing between the positive and negative pole pieces in the inner circle of the corner is large, which worsens the charging and discharging at this location, resulting in the problem of lithium deposition in the inner circle of the corner, affecting the reliability and cycle life of the battery cell.

[0085] 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 isolation film to support the inner circle pole piece. In the hot pressing shaping process after the winding is completed, the curvature radius of the inner circle pole piece at the corner is increased, which is not easy to break, reducing the problem of burrs and powder shedding after breaking, improving the problem of internal short of the battery cell, and improving the reliability of the battery cell. In addition, the problem of loose inner circle pole pieces can be improved. After hot pressing shaping, the gap between the inner circle pole pieces at the corner can be reduced, so that the spacing between the positive pole piece and the negative pole piece at the inner circle position at the corner can be reduced, so as to reduce the risk of lithium plating at the inner circle position at the corner, and improve the reliability and cycle life of the battery cell. Furthermore, 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, thereby facilitating 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 to the inner circle pole piece and further improving the reliability of the battery cell.

[0086] The technical solutions described in the embodiments of the present application are applicable to battery cells, batteries including battery cells, and electrical devices using batteries.

[0087] The electrical device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle may be a fuel vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, and the like; the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, and the like; the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, and the like; the electric tool may include a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and an electric tool for railways, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator, and an electric planer, and the like. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0088] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0089] Please refer to Figure 1 , Figure 1 This 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 may be disposed at the bottom, head, or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000. For example, the battery 100 may be used as an operating power source for the vehicle 1000.

[0090] The vehicle 1000 may further include a controller 200 and a motor 300 , wherein 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 starting, navigating, and driving the vehicle 1000 .

[0091] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0092] Please refer to Figure 2 , Figure 2 The exploded view of the battery 100 provided in some embodiments of the present application includes a battery cell 102 and a box 101 for accommodating the battery cell 102. The box 101 can be in various structural forms.

[0093] In some embodiments, the box body 101 may include a first portion 1011 and a second portion 1012, the first portion 1011 and the second portion 1012 cover each other, and the first portion 1011 and the second portion 1012 together define a storage space for accommodating the battery cell 102. Figure 2 , the first part 1011 and the second part 1012 can both be hollow structures with one side open, and the open side of the first part 1011 covers the open side of the second part 1012, so as to form a box body 101 with a storage space. A sealing member can also be provided between the first part 1011 and the second part 1012 to achieve a sealed connection between the first part 1011 and the second part 1012. For another example, the second part 1012 can be a hollow structure with one side open, the first part 1011 is in the form of a cover and can cover the top of the second part 1012, and the first part 1011 and the second part 1012 can be in various shapes, such as a cylinder, a cuboid, etc.

[0094] In the battery 100, there may be one or more battery cells 102. If there are more than one battery cell 102, the multiple battery cells 102 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 102 are connected in series and in parallel. The multiple battery cells 102 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 102 may be accommodated in the box 101; of course, the multiple battery cells 102 may be first connected in series, in parallel, or in a mixed connection to form a battery 100 module, and the multiple battery 100 modules may be connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 101. In some embodiments, the multiple battery cells 102 may be electrically connected through a busbar component to achieve parallel, series, or mixed connection of the multiple battery cells 102.

[0095] Each battery cell 102 may be a secondary battery 100 or a primary battery 100; it may 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 may be cylindrical, flat, rectangular, etc. For example, referring to Figure 3 In the illustrated embodiment, the battery cell 102 is in the form of a rectangular parallelepiped.

[0096] Reference Figure 3 and Figure 4 Some embodiments of the present application provide a battery cell 102, which 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 in the receiving cavity 13. The battery cell 2 includes at least one electrode assembly 3. That is, the battery cell 2 may include one electrode assembly 3 or may include multiple electrode assemblies 3, and the number of electrode assemblies 3 may be selected according to the capacity requirements of the battery cell 102.

[0097] For example, in combination 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. It is worth noting that the material of the shell 1 can be various, 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. Exemplarily, 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.

[0098] In the embodiments of the present application, Figure 4 and Figure 5 After winding to obtain the electrode assembly 3, the electrode assembly 3 is hot pressed and shaped to obtain a flat, substantially rectangular 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 an arc form.

[0099] For example Figure 4As shown, 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 corners 3b are located at both ends of the main body 3a in the third direction F3. In this way, by hot pressing the electrode assembly 3, on the one hand, it is convenient to install the electrode assembly 3 into the housing 1, and on the other hand, the interlayer gap of the electrode assembly 3 can be reduced by hot pressing, so that under the premise of the same volume of the accommodating cavity 13, the number of turns of the electrode assembly 3 can be increased, which is conducive to improving the energy density of the battery cell 102.

[0100] Of course, the present application is not limited thereto. For example, in other embodiments of the present application, the winding needle can be designed so that the wound electrode assembly 3 is directly in a flat rectangular shape, that is, the shape after winding is consistent with the shape after the aforementioned hot pressing shaping. In order to simplify the description, the following description is based on the example that the electrode assembly 3 needs to be hot pressed after winding.

[0101] Combination Figure 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 can be elastically deformed.

[0102] Combination Figure 5 In the embodiment of the present application, the isolation film 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, and the extension portion 32b is connected to the elastic pad 4. That is, the isolation film 32 includes the winding portion 32a and the extension portion 32b, and the portion where the isolation film 32 and the pole piece 31 are stacked and wound together is the winding portion 32a. The isolation film 32 isolates the positive pole piece and the negative pole piece in the pole piece 31 through the winding portion 32a, and the extension portion 32b connects the starting end of the winding portion 32a and the elastic pad 4.

[0103] 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 circle separator, and supports the electrode pieces 31 of the inner circles of the electrode assembly 3 ("inner circles" refers to at least one circle from the innermost circle), so that the curvature radius of the electrode pieces 31 of the inner circles of the corner portion 3b is increased, and it is not easy to break, thereby improving the burr and powder removal caused by breaking and other problems, reducing the probability of internal short of the battery cell 102, and improving the reliability of the battery cell 102. In addition, by providing the elastic pad 4 at the center of the winding to support the electrode pieces 31 of the inner circles of the electrode assembly 3, the problem of looseness of the electrode pieces 31 of the inner circles of the electrode assembly 3 can be improved, and the gap between the positive electrode pieces and the negative electrode pieces of the inner circles of the corner portion 3b can be reduced, so that the spacing between the positive electrode pieces and the negative electrode pieces of the inner circles of the corner portion 3b is reduced, so as to reduce the risk of lithium deposition at the inner circle position of the corner portion 3b, and improve 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 is convenient for the winding process of the electrode assembly 3 and the processing and manufacturing of the battery cell 102. In addition, 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 pole pieces 31 of several inner circles, and further improving the reliability of the battery cell 102.

[0104] In some embodiments of the present application, Figure 5 As shown, 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 stacked and connected with at least part of the elastic pad 4 and is wound together with the elastic pad 4. Therefore, by stacking the extension portion 32b with at least part of the elastic pad 4, the connection difficulty of the elastic pad 4 and the extension portion 32b can be reduced, and the connection reliability of 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 the processing efficiency and reducing the processing difficulty.

[0105] In some embodiments of the present application, Figure 5 As shown, the elastic pad 4 is wound at least once. Thus, since the elastic pad 4 is wound at least once, the thickness direction of the electrode assembly 3 (eg Figure 5In the second direction F2 shown in FIG, at least two layers of elastic pads 4 are provided at the main body 3a. For example, when the elastic pad 4 is wound once, two layers of elastic pads 4 are provided at the main body 3a, and when the elastic pad 4 is wound twice, four layers of elastic pads 4 are provided at the main body 3a, thereby improving the supporting effect of the main body 3a on the electrode assembly 3. Moreover, the elastic pad 4 wound at least once has rounded transitions at the corners 3b on both sides, and the pole pieces 31 of the inner circles of the corners 3b on both sides can be supported in rounded forms, thereby improving the supporting effect of the elastic pad 4 on the inner circles of the pole pieces 31 of the inner circles of the corners 3b, and improving the breakage problem of the pole pieces 31 of the inner circles of the corners 3b and the lithium deposition problem of the corners 3b.

[0106] In some embodiments of the present application, Figure 6 As shown, 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 .

[0107] 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.

[0108] At this time, the shape of the elastic pad 4 of the outermost circle can naturally match the shape of the pole piece 31 of the innermost circle, so that the elastic pad 4 can continuously support the pole piece 31 of the innermost circle throughout the entire circumference, so that the force applied to the pole piece 31 of the innermost circle at various positions throughout the entire circumference is 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 circle pole piece 31 can be improved, and the local fracture problem caused by the uneven stress distribution of the inner circle pole piece 31 can be improved, thereby improving the reliability of the battery cell 102.

[0109] In some other embodiments of the present application, Figure 5 As shown, when the elastic pad 4 is wound at least one circle, at least a portion of the extension portion 32 b can also be wound around the outer periphery of the first buffer structure 41 .

[0110] Exemplarily, the extension portion 32b can be completely wound around the outer periphery of the first buffer structure 41, or exemplary, the extension portion 32b can also be partially wound inside the elastic pad 4, and the remaining part is wound around the outer periphery of the first buffer structure 41. Exemplarily, if the extension portion 32b is longer, the entire outer periphery of the first buffer structure 41 can be wound by the extension portion 32b; and if the extension portion 32b is shorter, the outer periphery of the first buffer structure 41 can be partially wound by the extension portion 32b.

[0111] In this way, a flexible connection between the elastic pad 4 and the extension portion 32b can be achieved. In addition, when the entire outer circumference of the first buffer structure 41 is wrapped by the extension portion 32b, it is beneficial to increase the connection area and connection reliability between the elastic pad 4 and the extension portion 32b. When the outer circumference of the first buffer structure 41 is partially wrapped by the extension portion 32b, it is beneficial to use the remaining part of the outer circumference of the first buffer structure 41 to directly support the pole piece 31, which is beneficial to the elastic pad 4 to support the innermost pole piece 31.

[0112] For example, in some embodiments, more than half of the outer circumference of the first buffer structure 41 is wound by the pole piece 31, and the rest of the outer circumference is wound by the extension portion 32b. In this way, since the portion of the pole piece 31 wound around the outer circumference of the first buffer structure 41 exceeds half a circle, the portion of the extension portion 32b wound around the outer circumference of the first buffer structure 41 is less than half a circle.

[0113] In the above technical solution, since at least part of the extension part 32b is wound around the outer periphery of the first buffer structure 41, the pole piece 31 and the extension part 32b are relay wound around the entire circle of the outer periphery of the first buffer structure 41, which is conducive to the flexible feeding of the pole piece 31 and convenient processing. Moreover, since the part of the pole piece 31 wound around the outer periphery of the first buffer structure 41 exceeds half a circle, the outer peripheral shape of the first buffer structure 41 can naturally match the shape of the innermost circle pole piece 31, and the elastic pad 4 can play a more effective supporting role for the innermost circle pole piece 31 within a larger circumference range, so that the force at each position of the innermost circle pole piece 31 is 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 innermost circle pole piece 31 can be improved, and the local fracture problem caused by the uneven stress distribution of the innermost circle pole piece 31 can be improved, thereby improving the reliability of the battery cell 102.

[0114] Alternatively, when the outer circumference of the first buffer structure 41 is not wrapped by the pole piece 31, in some embodiments, it can be arranged that the entire outer circumference of the first buffer structure 41 is wrapped by the extension portion 32b, and the entire outer circumference 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.

[0115] In some embodiments of the present application, Figure 5 As shown, when more than half of the outer circumference of the first buffer structure 41 is wound by the pole piece 31, and the rest of the outer circumference is wound by the extension part 32b, the part of the extension part 32b wound around the outer circumference of the first buffer structure 41 can be arranged at one of the corner parts 3b. As a result, the elastic pad 4 can play a more effective supporting role for the innermost pole piece 31 at both sides of the main body 3a and at one of the corner parts 3b, and the innermost pole piece 31 is supported over a larger circumference range, thereby further improving the performance of the battery cell 102.

[0116] In some embodiments of the present application, Figure 5 As shown, when the elastic pad 4 is wound and wound for at least one circle, the winding tail end 411 of the elastic pad 4 can be set at the corner portion 3b. Therefore, by setting the winding 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, and improve the problem of local stress concentration cracking of the innermost pole piece 31 at the main body 3a.

[0117] Specifically, by shaping the winding tail end 411 of the elastic pad 4 at the corner portion 3b, compared with setting the winding tail end 411 at 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, and the risk of wrinkling and lithium deposition on the large surface of the electrode assembly 3 is reduced, thereby improving the reliability of the battery cell 102. In addition, the outermost circle of the elastic pad 4 is a continuous surface at the portion corresponding to the main body 3a, so that the innermost circle of the pole piece 31 can be well fitted with the outermost circle of the elastic pad 4 at the portion corresponding to the main body 3a, which is conducive to reducing the problem of wrinkling and cracking of the innermost circle of the pole piece 31 at the large surface position. 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 deposition problem at the corner portion 3b.

[0118] In some embodiments of the present application, Figure 5 As shown, 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 be arranged at the corner portion 3b. Figure 5 and Figure 6 As shown, the winding tail end 411 and the winding head end 412 can be arranged at the same corner portion 3b. In other examples, such as Figure 7 As shown, the winding tail end 411 and the winding head end 412 can also be arranged at the two corner portions 3b respectively.

[0119] Therefore, by setting the winding tail end 411 and the winding head end 412 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 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.

[0120] In some embodiments of the present application, Figure 5-Figure 8 As shown, the winding tail end 411 of the elastic pad 4 is connected to the extension part 32b in a stacked manner. Thus, only the end of the elastic pad 4 is connected to the extension part 32b, thereby facilitating the connection between the elastic pad 4 and the extension part 32b and reducing the difficulty of connecting the two.

[0121] 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 portion 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.

[0122] Exemplarily, the extension portion 32b is integrally connected to the elastic pad 4 in a stacked manner, and in this case, the portion where the isolation film 32 is stacked and connected to the elastic pad 4 is the extension portion 32b. Further, the extension portion 32b is integrally connected to the winding tail end 411 of the elastic pad 4 in a stacked manner, and in this case, the portion where the isolation film 32 is stacked and connected to the winding tail end 411 of the elastic pad 4 is the extension portion 32b.

[0123] Of course, the extension part 32b may not only be connected in a stacked manner with 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 be connected in a stacked manner with the extension part 32b in the entire length interval along the winding direction, thereby improving the connection reliability between the elastic pad 4 and the extension part 32b, and improving the flatness of the inner ring support, and improving the wrinkle and misalignment problems of the innermost ring pole piece 31. For example, the outer side surface and / or the inner side surface of the elastic pad 4 may be integrally attached to the extension part 32b, and the extension part 32b may be wound at the same time during the entire process of winding the elastic pad 4.

[0124] In some embodiments of the present application, Figure 5 and Fig. 9 As shown, when the winding tail end 411 of the elastic pad 4 is connected with the extension part 32b in a stacked manner, the overlapping length W of the extension part 32b and the elastic pad 4 can be less than or equal to 10mm. Therefore, on the one hand, the material of the extension part 32b can be saved, and on the other hand, when the portion of the extension part 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 wound by the extension part 32b can be reduced, so as to lengthen the length of the outer periphery of the first buffer structure 41 wound by the pole piece 31, thereby increasing the support range of the elastic pad 4 to the innermost pole piece 31. Moreover, it meets the tolerance requirements and is easy to process.

[0125] In some embodiments of the present application, the length of the extension portion 32b may be less than or equal to 10 mm. Thus, the material of the extension portion 32b can be further saved. 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 wound by the extension portion 32b can be further reduced, so as to lengthen the length of the outer periphery of the first buffer structure 41 wound by the pole piece 31, thereby increasing the support range of the elastic pad 4 for the innermost pole piece 31.

[0126] In some embodiments of the present application, Figure 5 As shown, the pole piece 31 includes a first pole piece 311 and a second pole piece 312, one of the first pole piece 311 and the second pole piece 312 is a positive pole piece, and the other is a negative pole piece. The innermost circle of the first pole piece 311 is wound around the outer periphery of the first buffer structure 41, that is, at least part of the outer periphery of the first buffer structure 41 is wound by the first pole piece 311. The isolation film 32 includes a first isolation film 321 and a second isolation film 322, the first isolation film 321 is isolated between the outer side surface of the first pole piece 311 and the inner side surface of the second pole piece 312, the second isolation film 322 is isolated between the outer side surface of the second pole piece 312 and the inner side surface of the first pole piece 311, and the innermost circle of the first pole piece 311 is located between the innermost circle of the first isolation film 321 and the outermost circle of the elastic pad 4. Among them, the two side surfaces in the thickness direction of each pole piece 31 are the inner side surface and the outer side surface, respectively, and the inner side surface is opposite to the outer side surface toward the winding center of the electrode assembly 3.

[0127] Exemplarily, 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.

[0128] 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, that is, 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. Therefore, 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, so that the innermost circle shape of the first pole piece 311 is consistent with the outermost circle shape of the elastic pad 4, so that the elastic pad 4 can reliably support the innermost circle of the pole piece 31, thereby improving the reliability of the battery cell 102.

[0129] Exemplarily, the extension portion 32b includes a first extension portion 32b1 disposed at the starting end of the first isolation film 321 and connected to the elastic pad 4. Thus, the innermost circle of the first pole piece 311 is located between the innermost circle of the first isolation film 321 and the outermost circle of the elastic pad 4. Since the first isolation film 321 has the first extension portion 32b1 at the starting end connected to the elastic pad 4, during the winding process of the electrode assembly 3, the innermost circle of the first isolation film 321 can relatively stably constrain the shape of the innermost circle of the first pole piece 311 to match the outer peripheral shape of the first buffer structure 41, so that the elastic pad 4 can reliably and stably support the innermost circle of the pole piece 31, thereby improving the reliability of the battery cell 102.

[0130] Exemplarily, the extension portion 32b includes a second extension portion 32b2 provided at the starting end of the second isolation film 322 and connected to the elastic pad 4. Thus, since the starting end of the second isolation film 322 has the second extension portion 32b2 connected to the elastic pad 4, during the winding process of the electrode assembly 3, the innermost circle of the second isolation film 322 can pass through the innermost circle of the second pole piece 312 and the innermost circle of the first isolation film 321, and more reliably constrain the shape of the innermost circle of the first pole piece 311 to match the outer peripheral shape of the first buffer structure 41, so that the elastic pad 4 can reliably and stably support the innermost circle of the pole piece 31, thereby improving the reliability of the battery cell 102.

[0131] Exemplarily, the extension portion 32b includes a first extension portion 32b1 disposed at the starting end of the first isolation film 321 and connected to the elastic pad 4, and at the same time, the extension portion 32b includes a second extension portion 32b2 disposed at the starting end of the second isolation film 322 and connected to the elastic pad 4. Thus, during the winding process of the electrode assembly 3, the innermost circle of the first isolation film 321 and the innermost circle of the second isolation film 322 can both relatively stably constrain the shape of the innermost circle of the first pole piece 311 to be consistent with the outer peripheral shape of the first buffer structure 41, so that the elastic pad 4 can reliably and stably support the innermost circle of the pole piece 31, thereby improving the reliability of the battery cell 102.

[0132] In some embodiments, for example Fig. 9, 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 winding tail end 411 of the elastic pad 4. That is, the extension portion 32b includes a first extension portion 32b1 provided at the starting end of the first isolation membrane 321 and connected to the elastic pad 4, and at the same time, the extension portion 32b includes a second extension portion 32b2 provided at the starting end of the second isolation membrane 322 and connected to the elastic pad 4, and the first extension portion 32b1 and the second extension portion 32b2 can be located on the same side of the winding tail end 411 of the elastic pad 4. For example, the first extension portion 32b1 and the second extension portion 32b2 can be both connected to the inner side surface of the elastic pad 4, or both connected to the outer side surface of the elastic pad 4, so as to facilitate the connection, which is conducive to reducing the difficulty of processing and improving the processing efficiency.

[0133] In some embodiments, for example Figure 8 , the starting ends of the first isolation film 321 and the second isolation film 322 are both provided with extensions 32b and are located on the opposite sides of the winding tail end 411 of the elastic pad 4. That is, the extension 32b includes a first extension 32b1 provided at the starting end of the first isolation film 321 and connected to the elastic pad 4, and at the same time, the extension 32b includes a second extension 32b2 provided at the starting end of the second isolation film 322 and connected to the elastic pad 4, and the first extension 32b1 and the second extension 32b2 can be located on both sides of the winding tail end 411 of the elastic pad 4. For example, one of the first extension 32b1 and the second extension 32b2 is connected to the inner side surface of the elastic pad 4, and the other is connected to the outer side surface of the elastic pad 4, which is conducive to improving the connection reliability of each of the first extension 32b1 and the second extension 32b2 with the elastic pad 4, and improving the reliability of the first isolation film 321 and the second isolation film 322 to constrain the shape of the innermost circle of the first pole piece 311.

[0134] 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.

[0135] For example, when the elastic pad 4 is wound at least one circle, in the thickness direction of the electrode assembly 3 (eg Figure 5 In the second direction F2) shown in FIG. 1 , it is equivalent to setting at least two layers of elastic pads 4. For example, when the elastic pad 4 is wound around once, the elastic pad 4 is combined with the elastic pad 4. Figure 5 , then in the thickness direction of the electrode assembly 3, it is equivalent to setting two layers of elastic pads 4. At this time, the thickness of the first buffer structure 41 formed by winding the elastic pad 4 is twice the thickness of the elastic pad 4. When the elastic pad 4 is wound twice, the thickness of the first buffer structure 41 is twice the thickness of the elastic pad 4. Figure 6, then in the thickness direction of the electrode assembly 3, it is equivalent to setting four layers of elastic pads 4. At this time, the thickness of the first buffer structure 41 formed by winding 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 turns, combined with Figure 7 , then 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 winding the elastic pad 4 is three times the thickness of the elastic pad 4, and so on.

[0136] Specifically, if the thickness of the elastic pad 4 is relatively thin, when the winding needle 50 is pulled out, the elastic pad 4 will be wrinkled, affecting the flatness of the electrode assembly 3, and if the thickness of the first buffer structure 41 formed by winding the elastic pad 4 is relatively 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. If the single layer thickness of the elastic pad 4 is relatively large, the deformation variation during winding is relatively large, and it is difficult to control the shape. Moreover, if the thickness of the first buffer structure 41 formed by winding the elastic pad 4 is relatively large, it occupies more space, affecting the energy density of the electrode assembly 3.

[0137] 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.

[0138] 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.

[0139] 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 one or more composite materials, which are not limited here.

[0140] In some embodiments of the present application, the inner side (i.e., the side surface facing the winding center) and / or the outer side (i.e., the side surface away from the winding center) of the elastic pad 4 has a glue layer. Therefore, since the elastic pad 4 is wound, the glue layer can be used to bond two adjacent layers of the elastic pad 4, reducing the gap between the layers of the elastic pad 4, which is conducive to the subsequent installation of the connected elastic pad 4 and the electrode assembly 3 into the shell 1 of the battery cell 102, that is, easy to put into the shell. Moreover, since the electrode assembly 3 is wound outside the elastic pad 4, when the outer side of the elastic pad 4 has a glue layer, the glue layer can be used to achieve the bonding of the innermost circle of the electrode assembly 3 and the outermost circle of the elastic pad 4, thereby improving the connection stability of the electrode assembly 3 and the elastic pad 4, improving the problem of separation of the electrode assembly 3 and the elastic pad 4 from the electrode assembly 3 after hot pressing, and forming a gap between the elastic pad 4 and the electrode assembly 3, which is conducive to the subsequent installation of the connected elastic pad 4 and the electrode assembly 3 into the shell 1 of the battery cell 102, that is, easy to put into the shell, and is conducive to improving the support reliability of the elastic pad 4 to the electrode assembly 3, and further reducing the risk of lithium precipitation caused by the looseness of the inner ring pole piece 31. It is worth noting that the material of the glue layer is not limited, for example, it can be a PVDF polyvinylidene fluoride coating, etc., so that during hot pressing, the layers of elastic pads 4 and the elastic pads 4 and the electrode assembly 3 can be tightly combined.

[0141] The elastic pad 4 may also be arranged in a non-wound manner. For example, in some embodiments of the present application, Fig.10 The elastic pad 4 can also be in the form of a single piece or multiple pieces stacked to form the second buffer structure 42, that is, the second buffer structure 42 is composed of a single layer or multiple layers of elastic pads 4, and the extension portion 32b is connected to the second buffer structure 42. At this time, 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.

[0142] For example, when the elastic pad 4 is a single-piece or multi-piece stacked second buffer structure 42, combined with Fig.10 The extension portion 32b may be connected to the outer surface of the second buffer structure 42 in the thickness direction (eg Fig.10 The two side surfaces in the second direction F2) shown in FIG. 4 are connected to each other, thereby facilitating the connection between the elastic pad 4 and the extension portion 32b, with a larger connection area and better connection reliability.

[0143] For example, when the elastic pad 4 is a single-piece or multi-piece stacked second buffer structure 42, combined with Fig.11 The extension portion 32b may 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.

[0144] In some embodiments of the present application, Fig.10The entire outer circumference of the second buffer structure 42 is surrounded by the extension part 32b, and each side surface of the second buffer structure 42 in the thickness direction is connected to the extension part 32b in the entire length interval along the winding direction of the extension part 32b. In this way, the connection reliability between the elastic pad 4 and the extension part 32b can be improved, and the flatness of the inner ring support can be improved, and the wrinkle and misalignment problems of the innermost ring pole piece 31 can be improved.

[0145] In some embodiments of the present application, Fig.11 , at least half of the outer circumference of the second buffer structure 42 is wound by the pole piece 31. 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 play a more effective supporting role for the innermost pole piece 31 within a larger circumference, so as to improve the performance of the battery cell 102.

[0146] In some embodiments of the present application, along the axial direction of the electrode assembly 3 (for example Figure 4 In the first direction F1 shown in FIG, the height of the elastic pad 4 is greater than the height of the pole piece 31. Therefore, the axial ends of the elastic pad 4 can correspond to the axial ends beyond 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 the problem caused by the pole piece 31 not being partially supported by the elastic pad 4, thereby facilitating further improving the reliability of the battery cell 102.

[0147] 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 understandable that after the electrode assembly 3 is wound, the portion of the separator 32 that exceeds the pole 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. Therefore, on the one hand, the height of the elastic pad 4 can be sufficient to fully support the pole piece 31 from the entire axial height, and 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.

[0148] In some embodiments of the present application, the elastic pad 4 has pores. The pores may be pores of the material itself or pores obtained by machining. Thus, when the elastic pad 4 is squeezed by the expanded electrode assembly 3, it can be compressed and provide an elastic reaction force to the electrode assembly 3. Since the elastic pad 4 supports the innermost pole piece 31, the force uniformity of the innermost pole piece 31 can be improved. Moreover, the pores can be used to store electrolyte. Compared with the elastic core in a solid or closed form, the amount of electrolyte injected into the housing 1 can be increased, and the cycle life of the battery cell 102 can be improved. Moreover, when the elastic pad 4 is squeezed by the expanded electrode assembly 3, the pores in the elastic pad 4 can be squeezed to discharge the electrolyte or gas, so that the elastic pad 4 is compressed instead of being stretched along the axial direction of the electrode assembly 3 such as the first direction F1, so that the axial end of the elastic pad 4 is stretched, and the axial side separation film 32 of the electrode assembly 3 is squeezed, causing the problem of the positive and negative pole pieces 31 being short inside, thereby further improving the reliability of the battery cell 102.

[0149] For example, if a closed structure such as an airbag is used to replace the elastic pad 4, since the airbag is a sealed structure, the residual space in the housing 1 is reduced, and the injection amount of the electrolyte is relatively low. Moreover, when the electrode assembly 3 expands and squeezes the airbag, since the airbag is a closed structure, the airbag will stretch along the axial direction of the electrode assembly 3 when squeezed, squeezing the axial side isolation membrane 32 of the electrode assembly 3, causing the problem of internal shorting of the pole piece 31. The elastic pad 4 used in the present application has pores, which can effectively solve the above technical problems.

[0150] The present application also provides a battery 100, including a battery cell 102 of any of the above solutions. Since the reliability of the battery cell 102 according to the embodiment of the present application is improved, it is helpful to improve the reliability of the battery 100. It is worth noting that the battery 100 according to the embodiment of the present application may include a box body 101 or may not include the box body 101.

[0151] Exemplarily, the battery 100 further includes a busbar component, and there are multiple battery cells 102, and at least two of them are electrically connected through the busbar component. Thus, multiple battery cells 102 can be connected in series and / or in parallel. 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 through a busbar component, and the cathode of the battery cell 102 is connected to the anode of the previous battery cell 102 through another busbar component.

[0152] The embodiment of the present application also provides an electric device, including the battery 100 of any of the above solutions, and the battery 100 provides electric energy for the electric device. The electric device can be any of the above-mentioned devices or systems using the battery 100. Since the reliability of the battery 100 is improved, it is beneficial to improve the working power performance of the electric device.

[0153] The present application also provides a method for processing a battery cell 102, Figure 3-Figure 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 a separator 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 separator 32 .

[0154] Combination Fig.12 The processing method of the battery cell 102 may include the following steps.

[0155] Step S10 connects the isolation film 32 and the elastic pad 4. Exemplarily, the isolation film 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, and at least a portion of the extension portion 32b can be stacked and connected to the inner side or outer side of the elastic pad 4. The connection method is not limited, for example, it can be thermal composite connection, perforated connection using a perforated member, or connected by gluing, etc.

[0156] 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 where the extension portion 32b is stacked and connected with 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.

[0157] Step S30: feeding the electrode piece 31.

[0158] Step S40 is to wind the electrode assembly 3 , so that the elastic pad 4 is arranged at the winding center of the electrode assembly 3 , so that the elastic pad 4 can support the electrode assembly 3 .

[0159] In the above technical solution, the processing method allows the winding center of the electrode assembly 3 to be first wound with the elastic pad 4, replacing the original inner circle separator, and supporting the pole pieces 31 of the inner circle of the electrode assembly 3, so that the curvature radius of the pole pieces 31 of the inner circle of the corner 3b is increased, and it is not easy to break, thereby improving the problems of burr and powder removal caused by breaking, reducing the probability of internal short of the battery cell 102, and improving the reliability of the battery cell 102. In addition, by arranging the elastic pad 4 at the winding center to support the pole pieces 31 of the inner circle of the electrode assembly 3, the problem of loose pole pieces 31 of the inner circle of the electrode assembly 3 can be improved, and the gap between the positive pole piece and the negative pole piece of the inner circle of the corner 3b is reduced, so that the spacing between the positive pole piece and the negative pole piece of the inner circle of the corner 3b is reduced, so as to reduce the risk of lithium deposition at the inner circle position of the corner 3b, and improve 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 is convenient for the winding process of the electrode assembly 3 and the processing and manufacturing of the battery cell 102. In addition, 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 pole pieces 31 of several inner circles, and further improving the reliability of the battery cell 102.

[0160] In some embodiments, in combination Fig.13 , step S10 of connecting the isolation film 32 and the elastic pad 4 specifically includes: step S11 of connecting the starting end of the isolation film 32 (here, the starting end of the isolation film 32 winding, that is, the end of the extension part 32b away from the winding part 32a) to the winding tail end 411 of the elastic pad 4. As a result, only the end of the elastic pad 4 is connected to the extension part 32b, which facilitates the connection between the elastic pad 4 and the extension part 32b and reduces the difficulty of connecting the two. Moreover, the length of the part of the elastic pad 4 and the extension part 32b wound together can be relatively short, thereby shortening the length of the extension part 32b and saving costs.

[0161] In some embodiments, in combination Fig.13, step S30 of feeding the pole piece 31 specifically includes: step S31 of feeding the pole piece 31 when winding to the winding tail end 411 of the elastic pad 4. In this way, the pole piece 31 can 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 pole piece 31. That is, when the elastic pad 4 is about to be wound, the pole piece 31 is wound in time, so that more than half of the outer periphery of the first buffer structure 41 is wound by the pole piece 31. Therefore, the outer peripheral shape of the first buffer structure 41 can naturally match the shape of the innermost circle pole piece 31, and the elastic pad 4 can play a more effective supporting role for the innermost circle pole piece 31 within a larger circumference, so that the forces at various positions of the innermost circle 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 circle pole piece 31 can be improved, and the local fracture problem caused by the uneven stress distribution of the inner circle pole piece 31 can be improved, thereby improving the reliability of the battery cell 102.

[0162] In some embodiments, in combination Fig.13 , step S20 of winding the elastic pad 4 specifically includes: step S21 of winding the elastic pad 4 at least one circle. In this way, since the elastic pad 4 is wound at least one circle, in the thickness direction of the electrode assembly 3, the main body 3a is equivalent to setting at least two layers of elastic pads 4, thereby improving the supporting effect of the main body 3a on the electrode assembly 3. Moreover, the elastic pad 4 wound at least one circle has rounded corner transitions 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 supporting effect of the elastic pad 4 on the inner circles of the pole pieces 31 at the corners 3b, thereby improving the breakage problem of the pole pieces 31 of the inner circles of the corners 3b and the lithium deposition problem of the corners 3b.

[0163] In some embodiments, in combination Fig.13 After step S40 of winding the electrode assembly 3, the method 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.

[0164] Therefore, by shaping the winding tail end 411 of the elastic pad 4 at the corner portion 3b, compared with setting the winding tail end 411 at the main body 3a, the problem of concave and convex marks on the main body 3a caused by the winding tail end 411 of the elastic pad 4 can be avoided, and the risk of wrinkling and lithium deposition on the large surface of the electrode assembly 3 is reduced, thereby improving the reliability of the battery cell 102. In addition, the outermost circle of the elastic pad 4 is a continuous surface at the portion corresponding to the main body 3a, so that the innermost circle of the pole piece 31 can be well fitted with the outermost circle of the elastic pad 4 at the portion corresponding to the main body 3a, which is conducive to reducing the problem of wrinkling and cracking of the innermost circle of the pole piece 31 at the large surface position. 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 deposition problem at the corner portion 3b.

[0165] In short, by shaping the winding 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 cracking of the innermost pole piece 31 at the main body 3a.

[0166] The present application also provides a processing device 2000 for processing a battery cell 102, Figure 3-Figure 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 a separator 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 separator 32. Fig.14 , the processing equipment 2000 may include: a winding tool 5, a connecting tool 6 and a cutting tool 7. 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 film 32 and the elastic pad 4, and the cutting tool 7 is used to cut the isolation film 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 whose positions can be interchanged.

[0167] Exemplarily, the winding tool 5 includes two winding needles 50 that can be exchanged 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. Exemplarily, 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 of the winding needles 50 is located at the first position and the other is located at the second position.

[0168] For example, in combination Fig.14 , the winding needle 50 at the first position is defined as the preparatory winding needle 52, and the winding needle 50 at the second position is defined as the working winding needle 51. The first position is located above the second position, and the connecting tool 6 and the cutting tool 7 are both located above the first position, and the connecting tool 6 is located above the cutting tool 7. During continuous production, the working winding needle 51 winds up an electrode assembly 3, and the preparatory winding needle 52 is ready to wind up the next electrode assembly 3. Specifically, the isolation film 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 film 32 and the elastic pad 4, so that a connection point is formed on the isolation film 32. The cutting tool 7 is used to cut the isolation film 32 below the connection point, and the isolation film 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, and combined with Fig.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 preparation winding needle 52 starts to wind the elastic pad 4, or after feeding the electrode piece 31, the preparation winding needle 52 can be moved from the first position to the second position to become the working winding needle 51, and the working winding needle 51 can be moved to the first position to become the preparation winding needle 52.

[0169] Therefore, the processing equipment 2000 is simple, can realize continuous production, and can improve production efficiency. In addition, the battery cell 102 processed by the above processing equipment 2000 allows the winding center of the electrode assembly 3 to be first rolled into the elastic pad 4, replacing the original inner circle isolation film, and supporting the pole piece 31 of the inner circle of the electrode assembly 3, so that the curvature radius of the pole piece 31 of the inner circle of the corner portion 3b is increased, and it is not easy to break, thereby improving the burr and powder removal caused by breaking, reducing the probability of internal short of the battery cell 102, and improving the reliability of the battery cell 102. Moreover, by arranging the elastic pad 4 at the winding center to support the pole pieces 31 of the inner circle of the electrode assembly 3, the problem of loose pole pieces 31 of the inner circle can be improved, and the gap between the positive pole piece and the negative pole piece of the inner circle of the corner 3b can be reduced, so that the spacing between the positive pole piece and the negative pole piece of the inner circle of the corner 3b is reduced, so as to reduce the risk of lithium deposition at the inner circle position of the corner 3b, and improve the reliability and cycle life of the battery cell 102. Moreover, since the isolation film 32 has an extension 32b connected to the elastic pad 4, it is convenient for the winding process of the electrode assembly 3 and the processing and manufacturing of the battery cell 102, and through the connection between the isolation film 32 and the elastic pad 4, the elastic pad 4 can be more stably supported at the winding center of the electrode assembly 3, improving the supporting effect of the elastic pad 4 on the pole pieces 31 of the inner circle, and further improving the reliability of the battery cell 102.

[0170] In some embodiments, the connecting tool 6 is a hot pressing tool. In this case, the isolation film 32 and the elastic pad 4 can be connected by thermal bonding. In this way, the isolation film 32 and the elastic pad 4 can be connected quickly and reliably. Of course, the present application is not limited to this. For example, the isolation film 32 and the elastic pad 4 can also be connected by bonding.

[0171] Below, refer to Figure 3-Figure 5 , describing a battery cell 102 according to a specific embodiment of the present application.

[0172] 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 film 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 film 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, and the surface of the elastic pad 4 has a glue layer.

[0173] 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 10mm, the extension portion 32b is wound around the periphery of the first buffer structure 41, and the portion of the extension portion 32b wound around the periphery of the first buffer structure 41 is arranged at one of the corner portions 3b, and the rest of the periphery of the first buffer structure 41 is wound by the pole piece 31.

[0174] Since the elastic pad 4 is wound once, in the thickness direction of the electrode assembly 3 (eg Figure 5 In the second direction F2 shown in FIG. 1 , it is equivalent to setting two layers of elastic pads 4, and the two layers of elastic pads 4 are rounded transitions at the corners. Moreover, after the elastic pad 4 is wound one circle, that is, after the elastic pad 4 is wound one circle, the winding tail end 411 of the elastic pad 4 and the winding head end 412 are basically spliced, such as the gap between the winding tail end 411 and the winding head end 412 does not exceed 1mm, so that the elastic pad 4 is annular. In this way, the cost can be reduced, the structure can be simplified, and the problem of the winding tail end 411 of the elastic pad 4 overlapping the elastic pad 4 and causing local protrusion can be avoided.

[0175] 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 shape 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 force on the innermost pole piece 31 at all positions around the entire circumference is 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 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.

[0176] Moreover, the pole piece 31 is directly supported by the elastic pad 4 wound in one circle, which is conducive to increasing the curvature of the innermost pole piece 31 at the corner position, improving the problem of burr and powder loss caused by the brittle fracture of the inner pole piece 31, thereby improving the reliability of the battery cell 102. In addition, the problem of loose inner pole piece 31 can be improved. After hot pressing and shaping, the gap between the inner positive pole piece and the negative pole piece at the corner part 3b of the electrode assembly 3 can be reduced to reduce the risk of lithium deposition at the inner position of the corner part 3b, and improve the reliability and cycle life of the battery cell 102.

[0177] The study found that if a bracket with a metal mesh coated with an insulating layer is used to support the center of the electrode assembly, the shape of this bracket is mostly elliptical, which cannot match the shape of the runway-shaped electrode assembly well. The force at each position of the innermost pole piece is uneven, and the metal mesh has a solid area and a mesh area, and the support effect on the pole piece is inconsistent, which will also lead to uneven force at each position of the innermost pole piece. These are all likely to cause the innermost pole piece to form a stress demarcation point, and fracture problems will occur at the stress demarcation point. In addition, the bracket with a metal mesh coated with an insulating layer is more complicated to manufacture and has a higher production cost than the elastic pad formed by winding at least one circle of the elastic pad.

[0178] In addition, if a hard gasket is used to support the electrode assembly, the hard gasket is not elastic and cannot balance the expansion force generated by the expansion of the electrode assembly through elastic deformation, and cannot improve the stress uniformity of the inner ring pole piece. The elastic pad 4 in the embodiment of the present application is made of elastic material and has a thickness greater than that of the isolation film 32, and is wound at least one circle and includes at least two layers, so that the elasticity can be better, which is conducive to better elastic support for the innermost ring pole piece 31, and can effectively balance the expansion force generated by the expansion of the electrode assembly 3 and improve the stress uniformity of the inner ring pole piece 31.

[0179] In addition, in the embodiments of the present application, when the electrode assembly 3 is manufactured by winding, since several circles of the elastic pad 4 are first wound in 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 needle is pulled out after the winding is completed, 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. This is beneficial to improving the flatness of the electrode assembly 3 and improving the reliability of the battery cell 102.

[0180] like Fig.14 As shown, when the working winding needle 51 is about to finish winding the previous electrode assembly 3, it is ready to replace the preparation winding needle 52 to wind the material. At this time, the isolation film 32 and the elastic pad 4 can be thermally compounded by the connecting tool 6, so that the isolation film 32 and the ends of the elastic pad 4 are fixedly connected, and then the cutting tool 7 is used to cut the isolation film 32, and the working winding needle 51 continues to wind the remaining isolation film 32, and then stops unloading, and the preparation winding needle 52 extends to clamp the elastic pad 4, exchanges positions with the working winding needle 51, and starts to wind the elastic pad 4, and then combines with the working winding needle 51. Fig.15 When the elastic pad 4 is about to be wound, the separator 32 can be wound, and the negative electrode sheet and the positive electrode sheet can be fed at the same time to wind the electrode assembly 3. In this way, uninterrupted continuous production can be achieved, and the structure of the winding center being the elastic pad 4 effectively improves the production efficiency.

[0181] In this way, it can be wound into a stacked and wound structure of, from the inside to the outside, 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. 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 of the negative electrode sheet. The innermost circle of the negative electrode sheet can extend along the elastic pad 4 almost a full circle. In this way, the innermost circle of the 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 of the 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.

[0182] 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 improve the flatness of the electrode assembly 3 and improve 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 along the outermost circle of the elastic pad 4 for almost the entire circle. 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 charging and discharging 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 piece 31 can be solved, thereby improving the reliability of the battery cell 102; on the other hand, the curvature of the innermost circle electrode piece 31 can be increased, and the problem of burr and powder shedding caused by the brittle fracture of the innermost circle electrode piece 31 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 piece 31 can be improved. After hot pressing and shaping, the gap between the inner circle electrode pieces 31 at the corner part 3b can be reduced, so that the spacing between the positive electrode piece and the negative electrode piece 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.

[0183] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0184] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

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

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

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

4. The battery cell according to claim 3, characterized in that: 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, characterized in that: At least a portion of the extension portion is wound around an outer circumference of the first buffer structure.

6. The battery cell according to claim 5, characterized in that: 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.

7. The battery cell according to claim 6, characterized in that: The electrode assembly includes a main body and corner portions located at two 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 claim 3, characterized in that: The electrode assembly comprises a main body and corner portions located at two 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 claim 2, characterized in that: The coiled tail end of the elastic pad is connected to the extending portion in a stacked manner.

10. The battery cell according to claim 9, characterized in that: 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 claim 2, characterized in that: 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, and 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, characterized in that: The extension part is provided at the starting ends of the first isolation membrane and the second isolation membrane, and the first extension part at the starting end of the first isolation membrane and the second extension part 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, characterized in that: The extension part is provided at the starting ends of the first isolation membrane and the second isolation membrane, and the first extension part at the starting end of the first isolation membrane and the second extension part 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 claim 2, characterized in that: The elastic pad is laminated and connected to the extension portion over the entire length section along the winding direction.

15. The battery cell according to claim 5, characterized in that: 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.

16. The battery cell according to claim 2, characterized in that: 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.

17. The battery cell according to claim 2, characterized in that: The inner side surface and / or the outer side surface of the elastic pad has a glue layer.

18. The battery cell according to claim 1, characterized in that: 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, characterized in that: 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, characterized in that: At least a portion of the extension portion is sandwiched between two adjacent layers of the elastic pads.

21. The battery cell according to claim 18, characterized in that: 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 claim 18, characterized in that: At least half of the outer circumference of the second buffer structure is wound by the pole piece.

23. A battery, characterized in that: Comprising a battery cell according to any one of claims 1-22.

24. An electrical device, characterized in that: Comprising a battery according to claim 23.

25. A processing equipment, characterized in that: Used for processing a battery cell, the battery cell comprising an electrode assembly and an elastic pad, the electrode assembly comprising a pole piece and a separator arranged in a winding manner, the elastic pad being 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, used 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.

26. The processing equipment according to claim 25, characterized in that The connecting tool is a hot pressing tool, which connects the isolation membrane and the elastic pad by thermal bonding.

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