Battery monomer, battery device, power utilization device and energy storage device

Abstract

The invention provides a battery monomer, a battery device, a power utilization device and an energy storage device, and belongs to the technical field of batteries. Each battery monomer comprises a pole piece and an isolating membrane, the pole piece and the isolating membrane are wound to form an electrode assembly, and the isolating membrane is positioned between the adjacent circles of pole pieces. The outermost ring of the electrode assembly is an isolating membrane, the part, wound by at least one circle from the isolating membrane opening end to the isolating membrane terminal, of the isolating membrane is an inner-ring diaphragm, and the part, wound by at least one circle from the isolating membrane terminal to the isolating membrane opening end, of the isolating membrane is an outer-ring diaphragm. And the thickness of the coating layer of the inner ring diaphragm is smaller than that of the coating layer of the outer ring diaphragm. The outer-ring diaphragm wraps the outermost-ring pole piece, stress borne by the pole piece can be transmitted to the outer-ring diaphragm, the thickness of the outer-ring diaphragm is increased, the strength and toughness of the outer-ring diaphragm are improved, and the outer-ring diaphragm can absorb more stress, so that the stress of the outer-ring pole piece is reduced, the possibility of breakage of the pole piece is reduced, the stability of the battery monomer is improved, and the service life of the battery monomer is prolonged.

Description

Technical Field

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

[0002] Energy conservation and emission reduction are the key to sustainable social development. Rechargeable batteries have the characteristics of storing or releasing energy as needed, so they are widely used in various electrical devices or energy storage systems, and are an important part of promoting energy transformation and sustainable development. For the new energy industry, battery technology is an important factor in its development.

[0003] During the charging and discharging process of the battery, the battery cells will expand. As the battery is charged and discharged, the stress inside the battery cells gradually accumulates, which may cause the electrode to break, affecting the stability and life of the battery. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems in the background technology. To this end, one object of the present application is to provide a battery cell, a battery device, an electrical device and an energy storage device to improve the stability and life of the battery.

[0005] An embodiment of the first aspect of the present application provides a battery cell, which includes a pole piece and a separator, which are wound to form an electrode assembly, and the separator is located between adjacent circles of pole pieces; the outermost circle of the electrode assembly is the separator, and the portion of the separator that is wound at least one circle from the start end of the separator to the end end of the separator is an inner circle separator, and the portion of the separator that is wound at least one circle from the end end of the separator to the start end of the separator is an outer circle separator; wherein the separator includes a base film and a coating layer, the coating layer is located on at least one side surface of the base film, and the thickness of the coating layer of the inner circle separator is less than the thickness of the coating layer of the outer circle separator.

[0006] In the technical solution of the embodiment of the present application, the outermost circle of the electrode assembly is the outer circle diaphragm, which wraps the outermost pole piece. The stress on the pole piece will be transmitted to the outer circle diaphragm. The thickness of the coating layer of the outer circle diaphragm increases the thickness of the outer circle diaphragm, and the strength and toughness of the outer circle diaphragm increase. The outer circle diaphragm can absorb more stress, thereby reducing the stress of the outer circle pole piece, reducing the possibility of pole piece breakage, and improving the stability and life of the battery cell.

[0007] In some embodiments, the pole piece includes a first pole piece and a second pole piece, the isolation membrane includes a first diaphragm and a second diaphragm, the first pole piece, the first diaphragm, the second pole piece and the second diaphragm are stacked and wound in sequence to form an electrode assembly, the outermost circle of the electrode assembly is the first diaphragm, and the outermost circle of the first pole piece wraps the outermost circle of the second pole piece; the first diaphragm includes an inner circle diaphragm and an outer circle diaphragm. Two layers of isolation membranes are provided, namely the first diaphragm and the second diaphragm. During the winding process, the first pole piece and the second pole piece of any two adjacent circles can be separated by one of the first diaphragm and the second diaphragm, thereby improving the stability of the battery cell. Since the first diaphragm is located at the outermost circle, both the stress of the first pole piece and the stress of the second pole piece will be transmitted to the first diaphragm. The outer circle diaphragm is provided on the first diaphragm, and the outer circle diaphragm of the first diaphragm can absorb more stress, reduce the stress of the pole piece, reduce the possibility of the pole piece breaking, and improve the stability and life of the battery cell.

[0008] In some embodiments, the second diaphragm includes an inner ring diaphragm and an outer ring diaphragm. There is stress in both the first pole piece and the second pole piece, the first pole piece transfers stress to the first diaphragm, and the second pole piece transfers stress to the second diaphragm. The outer ring diaphragm is arranged on the first diaphragm and the second diaphragm. The outer ring diaphragm of the first diaphragm and the outer ring diaphragm of the second diaphragm can absorb the stress of the first pole piece and the second pole piece, reduce the stress of the first pole piece and the second pole piece, reduce the possibility of the first pole piece and the second pole piece breaking, and improve the stability and life of the battery cell.

[0009] In some embodiments, the portion of the second pole piece that is wound one circle from the second pole piece terminal to the second pole piece start is the outer ring second pole piece, and the side of the outer ring diaphragm close to the start of the isolation membrane is opposite to the side of the outer ring second pole piece close to the start of the second pole piece. The side of the outer ring diaphragm close to the start of the isolation membrane is opposite to the side of the outer ring second pole piece close to the start of the second pole piece, so that the outer ring diaphragm can cover the outermost circle of the pole piece, and the outer ring diaphragm can absorb the stress of the outermost pole piece to reduce the stress of the pole piece.

[0010] In some embodiments, the inner diaphragm and the outer diaphragm on the same isolation membrane are adjacent. The portion of the isolation membrane without the outer diaphragm is the inner diaphragm, and the isolation membrane only includes two different thicknesses, which makes the isolation membrane manufacturing process simpler and simplifies the manufacturing process.

[0011] In some embodiments, the first pole piece is an anode piece, and the second pole piece is a cathode piece. The outermost circle of the first pole piece wraps the outermost circle of the second pole piece, and the first pole piece is set as an anode piece, and the second pole piece is set as a cathode piece, that is, the anode piece wraps the cathode piece, and the lithium ions generated by the cathode can be more fully and orderly embedded in the vacant position of the anode, which helps to improve the overall capacity of the battery cell and the stability of charging and discharging, and improve the reliability of the battery cell.

[0012] In some embodiments, a ratio of a thickness of the inner ring diaphragm to a thickness of the outer ring diaphragm is greater than or equal to 0.2 and less than or equal to 0.95.

[0013] In some embodiments, a ratio of a thickness of the inner ring diaphragm to a thickness of the outer ring diaphragm is greater than or equal to 0.3 and less than or equal to 0.85.

[0014] In some embodiments, the ratio of the thickness of the inner diaphragm to the thickness of the outer diaphragm is greater than or equal to 0.4 and less than or equal to 0.75. Limiting the ratio of the thickness of the inner diaphragm to the thickness of the outer diaphragm within the above range can improve the safety of the battery while reducing the impact on the energy density of the battery cell.

[0015] In some embodiments, the isolation film includes: a base film; a coating layer located on at least one side of the base film; wherein the thickness of the coating layer of the inner ring diaphragm is less than the thickness of the coating layer of the outer ring diaphragm. The coating layer is made on the surface of the base film by coating or other processes, and it is more convenient to change the thickness of the coating layer than to change the thickness of the base film.

[0016] In some embodiments, the coating layer is located on one side of the base film; for the outer ring diaphragm, the coating layer is located on both sides of the base film. The outer ring diaphragm is provided with two coating layers, and the manufacturing process of the coating layer of the inner ring diaphragm does not need to be changed, thereby simplifying the manufacturing process.

[0017] In some embodiments, the thickness of the coating layer satisfies at least one of the following conditions: for the inner ring diaphragm, the thickness of the coating layer is greater than or equal to 1 μm and less than or equal to 5 μm; for the outer ring diaphragm, the thickness of the coating layer located on one side surface of the base film is greater than or equal to 4 μm and less than or equal to 10 μm. The thickness of the coating layer in the inner ring diaphragm and the outer ring diaphragm is defined separately, and the thickness of the inner ring diaphragm and the thickness of the outer ring diaphragm can be adjusted by adjusting the thickness of the coating layer respectively.

[0018] In some embodiments, the material of the base film includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyolefin materials and polyolefin modified materials. The above materials have good liquid absorption and retention capabilities, can absorb and retain a certain amount of electrolyte, so that the electrolyte is evenly distributed inside the battery, providing a good medium environment for ion conduction, helping to improve the efficiency and uniformity of ion transmission inside the battery, and thus improving the overall performance and stability of the battery.

[0019] In some embodiments, the coating layer includes a ceramic coating, which enhances the high temperature resistance of the separator, improves the thermal stability of the separator, improves the thermal shrinkage of the separator, and can also enhance the puncture resistance of the separator, thereby improving the reliability of the battery.

[0020] In some embodiments, the material of the ceramic coating includes at least one of alumina, boehmite, silicon dioxide, zirconium oxide and titanium oxide. The above materials are relatively common ceramic coating materials, which are easy to obtain and reduce production costs.

[0021] In some embodiments, the porosity of the coating layer is greater than or equal to 40% and less than or equal to 80%. The porosity of the coating layer is limited to be greater than or equal to 40%, and the coating layer can provide a smooth transmission channel for lithium ions, so that lithium ions can move between the electrodes on both sides of the isolation membrane through these pores, thereby improving the charge and discharge performance and charge and discharge efficiency of the battery. The porosity of the coating layer is limited to be less than or equal to 80%, and the strength and isolation function of the isolation membrane will not be reduced due to excessive porosity, while reducing the impact on the isolation membrane adsorption of electrolyte.

[0022] In some embodiments, the isolation film further includes two adhesive layers, and the base film and the coating layer are located between the two adhesive layers. The adhesive layer can bond the pole piece to improve the firmness of the connection between the isolation film and the pole piece.

[0023] In some embodiments, the material of the adhesive layer includes at least one of polyvinylidene fluoride homopolymer, polyvinylidene fluoride copolymer, polyvinyl chloride, polyethylene oxide and polymethacrylic resin. The above materials have good adhesive properties and can improve the adhesive properties of the adhesive layer. At the same time, the above materials are easy to obtain, which reduces the cost of making the isolation film.

[0024] In some embodiments, the thickness of the adhesive layer is greater than or equal to 1 μm and less than or equal to 10 μm. The thickness of the adhesive layer is limited to be greater than or equal to 1 μm so that the isolation film has a sufficient adhesive layer for bonding the pole piece; the thickness of the adhesive layer is limited to be less than or equal to 10 μm to reduce the influence of the excessive thickness of the adhesive layer on the transmission of lithium ions.

[0025] In some embodiments, the adhesive force of the adhesive layer is greater than or equal to 5N and less than or equal to 25N. The adhesive force of the adhesive layer is limited to be greater than or equal to 5N, so that the adhesive layer has sufficient adhesive force to bond the pole piece; if the adhesive force of the adhesive layer is too strong, the contact between the separator and the pole piece may be too close, resulting in the transmission of lithium ions at the interface between the separator and the pole piece being hindered. The adhesive force of the adhesive layer is limited to be less than or equal to 25N, reducing the influence of the adhesive layer on the transmission of lithium ions.

[0026] In some embodiments, the electrode assembly has a curved region and a straight region, and the electrode piece includes a first sub-electrode piece and a second sub-electrode piece, the first sub-electrode piece is located in the curved region, and the second sub-electrode piece is at least located in the straight region; the thickness of the first sub-electrode piece is less than the thickness of the second sub-electrode piece. The portion of the electrode piece located in the curved region is set as a first sub-electrode piece with a smaller thickness, and the spacing between the first sub-electrode piece and its adjacent electrode piece is larger, so that the electrode piece located in the curved region has more expansion space, reduces the stress on the electrode piece, reduces the possibility of the electrode piece breaking, and improves the stability and life of the battery cell.

[0027] In some embodiments, the outermost pole piece of the bending region is the first sub-pole piece. Since the stress on the outermost pole piece of the bending region is greater than the stress on other pole pieces, setting the outermost pole piece of the bending region as the first sub-pole piece can reduce the stress on the outermost pole piece of the bending region to a greater extent, and reduce the possibility of the pole piece breaking.

[0028] In some embodiments, the second sub-pole piece is also located in the bending region. For the pole pieces with the same polarity, the first sub-pole piece located in the bending region has n turns, and there are m turns of second sub-pole pieces between any two adjacent turns of the first sub-pole piece from the turn of the first sub-pole piece to the (n-1) turn of the first sub-pole piece, and there are k turns of second sub-pole pieces between the (n-1) turn of the first sub-pole piece and the n turn of the first sub-pole piece, wherein m is an integer greater than or equal to 1 and less than or equal to 15, k is an integer less than or equal to m, and n is an integer greater than or equal to 3. As the thickness of the first sub-pole piece decreases, the strength of the first sub-pole piece decreases. In the embodiments of the present application, the first sub-pole pieces are arranged at intervals in the bending region to reduce the influence of the reduced strength of the first sub-pole piece on the strength of the bending region.

[0029] In some embodiments, when the pole piece includes a first pole piece and a second pole piece, the outermost portion of the first pole piece located in the bending area is the first sub-pole piece; the outermost portion of the second pole piece located in the bending area is the first sub-pole piece. Setting the outermost portions of the first pole piece and the second pole piece as the first sub-pole piece can reduce the possibility of the first pole piece and the second pole piece being broken.

[0030] In some embodiments, when the pole piece includes a first pole piece and a second pole piece, the first pole piece includes a first sub-pole piece and a second sub-pole piece, and the second pole piece includes a first sub-pole piece and a second sub-pole piece, and the number of turns of the first sub-pole piece in the first pole piece is equal to the number of turns of the first sub-pole piece in the second pole piece. The portion of the first pole piece with reduced thickness corresponds to the portion of the second pole piece with reduced thickness, and this portion of the first pole piece and the second pole piece can provide expansion space and can also reduce the impact on the energy density of the battery cell.

[0031] In some embodiments, the pole piece includes a current collector and an active material layer, the active material layer is located on at least one side of the current collector, and the first sub-pole piece and the second sub-pole piece meet one of the following conditions: the first sub-pole piece includes a current collector, and the second sub-pole piece includes a current collector and an active material layer; the first sub-pole piece and the second sub-pole piece both include a current collector and an active material layer, and the thickness of the active material layer of the first sub-pole piece is less than the thickness of the active material layer of the second sub-pole piece. The active material layer is made on the surface of the current collector by coating or other processes, and it is more convenient to change the thickness of the active material layer than to change the thickness of the current collector.

[0032] An embodiment of a second aspect of the present application provides a battery device, which includes the battery cell in the above embodiment.

[0033] An embodiment of the third aspect of the present application provides an electrical device, which includes the battery device in the above embodiment, and the battery device is used to provide electrical energy.

[0034] An embodiment of the fourth aspect of the present application provides an energy storage device, which includes the battery device in the above embodiment, and the battery device is used to store electrical energy.

[0035] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0037] Figure 1 A schematic diagram of the structure of a battery cell provided in an embodiment of the present application; Figure 2 for Figure 1 Interface diagram of the AA surface of the middle electrode assembly; Figure 3 A comparison diagram of the cross-sectional views of an inner ring diaphragm and an outer ring diaphragm provided in an embodiment of the present application; Figure 4 A cross-sectional view of another electrode assembly provided in an embodiment of the present application; Figure 5 A comparison diagram of a cross-sectional view of a first sub-pole piece and a second sub-pole piece provided in an embodiment of the present application; Figure 6 A cross-sectional view of another electrode assembly provided in an embodiment of the present application; Figure 7 A schematic diagram of an unfolded pole piece provided in an embodiment of the present application; Figure 8 A schematic diagram of the exploded structure of a battery device provided in some embodiments of the present application; Fig. 9 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application.

[0038] Description of reference numerals: 10, pole piece; 11, first pole piece; 12, second pole piece; 121, outer second pole piece; 13, first sub-pole piece; 14, second sub-pole piece; 15, current collector; 16, active material layer; 20, isolation film; 21, inner ring diaphragm; 22, outer ring diaphragm; 23, first diaphragm; 24, second diaphragm; 25, base film; 26, coating layer; 27, adhesive layer; 100, battery cell; 200, battery Pole assembly; 201, bending area; 202, straight area; 203, main body; 204, pole ear; 300, outer shell; 301, end cover; 311, electrode terminal; 312, pressure relief mechanism; 313, adapter; 302, shell; 400, battery device; 500, box; 501, first part; 502, second part; 600, controller; 700, motor; 1000, vehicle. DETAILED DESCRIPTION

[0039] The following embodiments of the technical solution of the present application will be described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein 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 figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0041] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0042] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations 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. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0043] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may 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 article generally indicates that the associated objects before and after are in an "or" relationship.

[0044] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0045] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0046] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like 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 mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0047] At present, from the perspective of market development, the application of rechargeable batteries is becoming more and more extensive. Rechargeable batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in various electronic devices, such as electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of rechargeable batteries, the market demand is also constantly expanding.

[0048] During the charge and discharge cycle of the battery, the battery cell will expand and the pole piece of the battery cell will be squeezed. As the number of charge and discharge cycles of the battery increases, the stress on the pole piece will gradually accumulate, and the stress will gradually transfer from the middle of the battery to the edge of the battery. For wound battery cells, the stress on the pole piece at the outermost circle is the greatest, making the pole piece at the outermost circle easy to break, affecting the stability and life of the battery.

[0049] The embodiment of the present application provides a battery cell, which includes a pole piece and a separator, which are wound to form an electrode assembly, and the separator is located between adjacent circles of pole pieces. The outermost circle of the electrode assembly is the separator, and the portion of the separator that is wound at least one circle from the beginning of the separator to the end of the separator is the inner circle separator, and the portion of the separator that is wound at least one circle from the end of the separator to the beginning of the separator is the outer circle separator. The thickness of the inner circle separator is less than the thickness of the outer circle separator. The outer circle separator wraps the outermost pole piece, and the stress on the pole piece will be transmitted to the outer circle separator. The thickness of the outer circle separator increases, and the strength and toughness of the outer circle separator increase. The outer circle separator can absorb more stress, thereby reducing the stress of the outer circle pole piece, reducing the possibility of pole piece breakage, and improving the stability and life of the battery cell.

[0050] The battery cells disclosed in the embodiments of the present application can be used, but not limited to, in electric devices or energy storage devices such as vehicles, ships or aircraft. The power supply system of the electric device or energy storage device can be composed of the battery cells and battery cells disclosed in the present application, which is conducive to reducing the possibility of electrode breakage and improving the stability of battery performance and battery life.

[0051] The present application embodiment provides a battery cell, Figure 1 This is a schematic diagram of the structure of a battery cell provided in an embodiment of the present application. Figure 1 , the battery cell 100 includes an electrode assembly 200 and a housing 300 .

[0052] Figure 2 for Figure 1 Schematic diagram of the interface of the AA surface of the middle electrode assembly. Figure 1 and Figure 2The battery cell 100 includes a pole piece 10 and a separator 20, which are wound to form an electrode assembly 200, and the separator 20 is located between adjacent circles of pole pieces 10. The outermost circle of the electrode assembly 200 is the separator 20, and the portion of the separator 20 wound at least one circle from the beginning of the separator to the end of the separator is the inner circle separator 21, and the portion of the separator 20 wound at least one circle from the end of the separator to the beginning of the separator is the outer circle separator 22.

[0053] Figure 3 This is a comparison diagram of the cross-sectional view of an inner ring diaphragm and an outer ring diaphragm provided in an embodiment of the present application. Figure 3 The isolation membrane 20 includes a base membrane 25 and a coating layer 26. The coating layer 26 is located on at least one side surface of the base membrane 25. The thickness D3 of the coating layer 26 of the inner ring diaphragm 21 is smaller than the thickness D4 of the coating layer 26 of the outer ring diaphragm 22, so that the thickness D1 of the inner ring diaphragm 21 is smaller than the thickness D2 of the outer ring diaphragm 22.

[0054] A battery cell 100 refers to the smallest unit constituting a battery. Figure 1 As shown, the housing 300 includes an end cap 301 and a shell 302. The end cap 301 refers to a component that covers the opening of the shell 302 to isolate the internal environment of the battery cell 100 from the external environment. Without limitation, the shape of the end cap 301 can be adapted to the shape of the shell 302 to match the shell 302. Optionally, the end cap 301 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 301 is not easily deformed when squeezed and collided, so that the battery cell 100 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals 311 can be provided on the end cap 301. The electrode terminal 311 can be used to electrically connect to the electrode assembly 200 for outputting or inputting electrical energy of the battery cell 100. In some embodiments, the end cap 301 can also be provided with a pressure relief mechanism 312 for releasing the internal pressure when the internal pressure or temperature of the battery cell 100 reaches a threshold. The material of the end cap 301 may also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating member may be provided inside the end cap 301, and the insulating member may be used to isolate the electrical connection components in the housing 302 from the end cap 301 to reduce the risk of short circuit. Exemplarily, the insulating member may be plastic, rubber, etc.

[0055] The shell 302 is a component used to cooperate with the end cap 301 to form the internal environment of the battery cell 100, wherein the formed internal environment can be used to accommodate the electrode assembly 200, the electrolyte and other components. The shell 302 and the end cap 301 can be independent components, and an opening can be set on the shell 302, and the internal environment of the battery cell 100 is formed by covering the opening with the end cap 301 at the opening. Without limitation, the end cap 301 and the shell 302 can also be integrated. Specifically, the end cap 301 and the shell 302 can form a common connection surface before other components are put into the shell, and when the interior of the shell 302 needs to be encapsulated, the end cap 301 covers the shell 302. The shell 302 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 302 can be determined according to the specific shape and size of the electrode assembly 200. The material of the shell 302 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0056] The electrode assembly 200 is a component in the battery cell 100 where electrochemical reactions occur, and the housing 302 may contain one or more electrode assemblies 200. The electrode assembly 200 is formed by winding a pole piece 10 and a separator 20. The portion of the pole piece 10 with active material constitutes the main body 203 of the electrode assembly 200, and the portion of the pole piece 10 without active material constitutes the pole ear 204. The electrode assembly 200 generally includes two pole ears 204 with opposite polarities, and the two pole ears 204 can be located together at one end of the main body 203 or at both ends of the main body 203. The pole ear 204 is connected to the electrode terminal 311 to form a current loop, wherein the pole ear 204 can be directly connected to the electrode terminal 311, or the pole ear 204 is connected to the electrode terminal 311 through the adapter 313.

[0057] In the embodiment of the present application, the electrode sheet 10 and the separator 20 are wound to form the electrode assembly 200, that is, the electrode assembly 200 is an electrode assembly with a wound structure. In the embodiment of the present application, the number of windings of the electrode assembly 200 can be set according to demand. For example, the number of windings of the electrode assembly 200 is greater than or equal to 10 and less than or equal to 60, for example, the number of windings of the electrode assembly 200 is 50.

[0058] There is an isolation film 20 between any two adjacent circles of pole pieces 10, so that pole pieces 10 with opposite polarities will not be in direct contact with each other, thereby reducing the risk of internal short circuit of the battery cell 100.

[0059] The outermost circle of the electrode assembly 200 is the isolation membrane 20, that is, the last circle of the electrode assembly 200 is the isolation membrane 20. The isolation membrane 20 wraps the pole piece 10. The isolation membrane 20 serves as an insulating layer to reduce the possibility of direct contact between the outermost pole piece 10 and the external environment, thereby reducing the risk of short circuit.

[0060] In the embodiment of the present application, the portion close to the winding center is the inner portion, and the portion far from the winding center is the outer portion. The outermost circle of the pole piece 10 is the portion of the last circle of the pole piece 10 being wound.

[0061] In the embodiment of the present application, the start end of the isolation film refers to the starting end of the isolation film 20 being wound, and the end end of the isolation film refers to the ending end of the isolation film 20 being wound.

[0062] It should be noted that Figure 3 Only a simplified cross-sectional view of the inner and outer diaphragms is shown.

[0063] The base film 25 provides a basic physical support structure for the isolation film 20, so that the isolation film 20 can maintain a certain shape and size. During the assembly and use of the battery, the base film 25 can withstand the pressure between the electrodes, the stress inside the battery, and the mechanical force that may be applied from the outside. The isolation film 20 will not be easily deformed, broken or damaged, and the stability of the internal structure of the battery is maintained. At the same time, the base film 25 can effectively separate the positive and negative electrodes of the battery, reduce the possibility of short circuits caused by direct contact between the positive and negative electrodes, and improve the reliability of the battery. The base film 25 can allow lithium ions and other ions required for the operation of the battery to selectively pass between the positive and negative electrodes, providing an ion transmission channel for the electrochemical reaction inside the battery. The base film 25 has a certain ability to absorb and retain liquid, and can adsorb and retain a certain amount of electrolyte, so that the electrolyte is evenly distributed inside the battery.

[0064] The coating layer 26 can optimize the ion transmission channel, so that lithium ions can be conducted more smoothly between the positive and negative electrodes, thereby improving the charge and discharge efficiency and rate performance of the battery. At the same time, the coating layer 26 can form a good contact with the electrode surface, and play a buffering and stabilizing role between the electrode and the separator 20. The coating layer 26 can increase the overall strength and toughness of the separator 20, improve the puncture resistance of the separator 20, reduce the possibility of the separator 20 being punctured by the electrode material or other foreign matter, and improve the stability of the battery. The coating layer 26 can absorb more electrolyte and retain it evenly inside the separator 20, providing sufficient medium for lithium ion conduction, killing the smooth ion conduction inside the battery, and also helping to maintain the stability of the electrolyte and reduce the volatilization and drying of the electrolyte. The coating layer 26 can improve the interface properties between the separator 20 and the electrolyte, reduce the interface resistance between the two, and make the transmission of lithium ions between the separator 20 and the electrolyte easier, thereby improving the overall performance of the battery, reducing the energy loss of the battery during the charge and discharge process, and improving the energy efficiency of the battery.

[0065] The coating layer 26 is made on the surface of the base film 25 by coating or other processes. Compared with changing the thickness of the base film 25 , it is more convenient to change the thickness of the coating layer 26 .

[0066] During the charge and discharge cycle of the battery cell 100, the distance between the pole pieces 10 will gradually increase, causing the battery cell 100 to expand outward. As the battery cell 100 expands, the stress inside the battery cell 100 will also gradually increase, and the stress on the battery cell 100 is transmitted from the inside of the battery cell 100 to the surroundings. For the pole pieces 10, the pole pieces 10 located in the outermost circle are subject to the greatest stress.

[0067] In the battery cell 100 provided in the embodiment of the present application, the outermost circle of the electrode assembly 200 is the outer circle diaphragm 22, and the outer circle diaphragm 22 wraps the outermost circle pole piece 10. The stress exerted on the pole piece 10 will be transmitted to the outer circle diaphragm 22. The thickness D4 of the coating layer 26 of the outer circle diaphragm 22 increases the thickness D2 of the outer circle diaphragm 22, and the strength and toughness of the outer circle diaphragm 22 are increased. The outer circle diaphragm 22 can absorb more stress, thereby reducing the stress of the outer circle pole piece 10, reducing the possibility of breakage of the pole piece 10, and improving the stability and life of the battery cell 100.

[0068] Toughness refers to the ability of a material to absorb energy during plastic deformation and rupture. The better the toughness, the less likely it is that a brittle fracture will occur. The toughness of the outer ring diaphragm 22 increases, the ability of the outer ring diaphragm 22 to absorb stress increases, the strength of the outer ring diaphragm 22 increases, and the ability of the outer ring diaphragm 22 to resist damage increases.

[0069] In the embodiment of the present application, the outer ring diaphragm 22 covers at least a whole circle of pole pieces 10 , and the outermost pole pieces 10 can transfer stress to the outer ring diaphragm 22 .

[0070] According to some embodiments of the present application, see Figure 2 The electrode piece 10 includes a first electrode piece 11 and a second electrode piece 12, and the isolation film 20 includes a first diaphragm 23 and a second diaphragm 24. The first electrode piece 11, the first diaphragm 23, the second electrode piece 12 and the second diaphragm 24 are sequentially stacked and wound to form an electrode assembly 200. The outermost circle of the electrode assembly 200 is the first diaphragm 23, and the outermost circle of the first electrode piece 11 wraps the outermost circle of the second electrode piece 12. The first diaphragm 23 includes an inner circle diaphragm 21 and an outer circle diaphragm 22.

[0071] In order to Figure 2 The pole piece 10 and the isolation film 20 are clearly shown. Figure 2 The first pole piece 11 is shown in red, the second pole piece 12 is shown in green, the first diaphragm 23 is shown in blue, and the second diaphragm 24 is shown in black. The lines of the inner ring diaphragm 21 are thinner than those of the outer ring diaphragm 22.

[0072] In the embodiment of the present application, the polarities of the first pole piece 11 and the second pole piece 12 are opposite.

[0073] In the initial stage of winding, the first diaphragm 23 is wound a certain distance ahead of the first pole piece 11 , and then the first pole piece 11 is wound, so that the first pole piece 11 at the winding center can be separated by the first diaphragm 23 .

[0074] At the end of the winding, the first pole piece 11 will continue to be wound at least one more time when the second pole piece 12 is wound, so that the outermost circle of the first pole piece 11 wraps the outermost circle of the second pole piece 12. The second diaphragm 24 will continue to be wound at least one more time when the first pole piece 11 is wound, so that the second diaphragm 24 can separate the first pole piece 11 from the second pole piece 12. The first diaphragm 23 will continue to be wound at least one more time when the second diaphragm 24 is wound, so that the outermost circle of the electrode assembly 200 is the first diaphragm 23.

[0075] In the embodiment of the present application, the outer ring diaphragm 22 of the first diaphragm 23 is the outermost ring of the electrode assembly 200 .

[0076] In the embodiment of the present application, two layers of separation membranes are provided, namely, the first diaphragm 23 and the second diaphragm 24. During the winding process, any two adjacent turns of the first pole piece 11 and the second pole piece 12 can be separated by one of the first diaphragm 23 and the second diaphragm 24, thereby improving the stability of the battery cell 100. Since the first diaphragm 23 is located at the outermost circle, both the stress of the first pole piece 11 and the stress of the second pole piece 12 will be transferred to the first diaphragm 23. The outer ring diaphragm 22 of the first diaphragm 23 is provided on the first diaphragm 23. The outer ring diaphragm 22 of the first diaphragm 23 can absorb more stress, reduce the stress of the pole piece 10, reduce the possibility of the pole piece 10 breaking, and improve the stability and life of the battery cell 100.

[0077] According to some embodiments of the present application, the second diaphragm 24 includes an inner ring diaphragm 21 and an outer ring diaphragm 22 .

[0078] Since the first pole piece 11 , the first diaphragm 23 , the second pole piece 12 and the second diaphragm 24 are sequentially stacked and wound to form the electrode assembly 200 , during the winding process, the first diaphragm 23 covers the first pole piece 11 , and the second diaphragm 24 covers the second pole piece 12 .

[0079] In the electrode assembly 200, stress exists in both the first pole piece 11 and the second pole piece 12. The first pole piece 11 transfers stress to the first diaphragm 23, and the second pole piece 12 transfers stress to the second diaphragm 24. An outer ring diaphragm 22 is arranged on the first diaphragm 23 and the second diaphragm 24. The outer ring diaphragm 22 of the first diaphragm 23 and the outer ring diaphragm 22 of the second diaphragm 24 can absorb the stress of the first pole piece 11 and the second pole piece 12, reduce the stress of the first pole piece 11 and the second pole piece 12, reduce the possibility of fracture of the first pole piece 11 and the second pole piece 12, and improve the stability and life of the battery cell 100.

[0080] In the embodiment of the present application, the first pole piece 11 transfers stress to the first diaphragm 23, which does not mean that the first pole piece 11 transfers stress only to the first diaphragm 23. The first pole piece 11 can transfer part of the stress to the first diaphragm 23 and also transfer part of the stress to the second diaphragm 24. Similarly, the second pole piece 12 can transfer part of the stress to the second diaphragm 24 and also transfer part of the stress to the first diaphragm 23.

[0081] According to some embodiments of the present application, the portion of the second pole piece 12 that is wound one circle from the second pole piece terminal end to the second pole piece starting end is the outer ring second pole piece 121, and the side of the outer ring diaphragm 22 close to the starting end of the isolation membrane is opposite to the side of the outer ring second pole piece 121 close to the starting end of the second pole piece.

[0082] In the embodiment of the present application, the second pole piece start end refers to the starting end of the winding of the second pole piece 12 , and the second pole piece terminal end refers to the terminating end of the winding of the second pole piece 12 .

[0083] Since the isolation membrane 20 needs to completely cover the pole piece 10, the isolation membrane 20 will continue to be wound after the pole piece 10 is wound. It can be understood that the terminal of the isolation membrane will exceed the terminal of the second pole piece. At the same time, the side of the outer ring diaphragm 22 close to the starting end of the isolation membrane is opposite to the side of the outer ring second pole piece 121 close to the starting end of the second pole piece, so the number of turns of the outer ring diaphragm 22 is greater than 1.

[0084] In an embodiment of the present application, the side of the outer ring diaphragm 22 close to the starting end of the isolation membrane is opposite to the side of the outer ring second pole piece 121 close to the starting end of the second pole piece, so that the outer ring diaphragm 22 can cover the outermost circle of the pole piece 10. The outer ring diaphragm 22 can absorb the stress of the outermost circle of the pole piece 10 and reduce the stress of the pole piece 10.

[0085] According to some embodiments of the present application, the inner ring diaphragm 21 and the outer ring diaphragm 22 located on the same isolation membrane 20 are adjacent to each other.

[0086] The inner ring diaphragm 21 and the outer ring diaphragm 22 on the same isolation membrane 20 are adjacent to each other, which can be understood as the inner ring diaphragm 21 and the outer ring diaphragm 22 having opposite sides overlapping. In the embodiment of the present application, it can be understood that for the same isolation membrane 20, a part of the isolation membrane is the inner ring diaphragm 21, and another part of the isolation membrane is the outer ring diaphragm 22.

[0087] In the embodiment of the present application, the inner ring diaphragm 21 of the first diaphragm 23 is adjacent to the outer ring diaphragm 22 of the first diaphragm 23 ; the inner ring diaphragm 21 of the second diaphragm 24 is adjacent to the outer ring diaphragm 22 of the second diaphragm 24 .

[0088] In the embodiment of the present application, the portion of the isolation membrane 20 excluding the outer ring diaphragm 22 is the inner ring diaphragm 21 , and the isolation membrane 20 only includes two different thicknesses. The process of manufacturing the isolation membrane 20 is simpler, and the manufacturing process is simplified.

[0089] In the embodiment of the present application, the portion of the second pole piece 12 wound at least one circle from the start of the second pole piece to the terminal of the second pole piece is the inner second pole piece; the portion of the first pole piece 11 wound at least one circle from the terminal of the first pole piece to the start of the first pole piece is the outer first pole piece; the portion of the first pole piece 11 wound at least one circle from the start of the first pole piece to the terminal of the first pole piece is the inner first pole piece. The side of the outer first pole piece close to the start of the first pole piece is opposite to the side of the outer second pole piece 121 close to the start of the second pole piece.

[0090] For example, see Figure 2 In the first pole piece 11, from B1 to B2 is the inner circle first pole piece, and from B2 to B3 is the outer circle first pole piece; in the second pole piece 12, from C1 to C2 is the inner circle second pole piece, and from C2 to C3 is the outer circle second pole piece; in the first diaphragm 23, from E1 to E2 is the inner circle diaphragm 21 of the first diaphragm 23, and from E2 to E3 is the outer circle diaphragm 22 of the first diaphragm 23; in the second diaphragm 24, from F1 to F2 is the inner circle diaphragm 21 of the second diaphragm 24, and from F2 to F3 is the outer circle diaphragm 22 of the second diaphragm 24. That is, B1 is the winding starting end of the first pole piece 11, and B3 is the winding ending end of the first pole piece 11; C1 is the winding starting end of the second pole piece 12, and C3 is the winding ending end of the second pole piece 12; E1 is the winding starting end of the first diaphragm 23, and E3 is the winding ending end of the first diaphragm 23; F1 is the winding starting end of the second diaphragm 24, and F3 is the winding ending end of the second diaphragm 24.

[0091] exist Figure 2 In the figure, the number of windings of the first pole piece 11, the second pole piece 12, the first diaphragm 23 and the second diaphragm 24 is only an example.

[0092] According to some embodiments of the present application, the first pole piece 11 is an anode piece, and the second pole piece 12 is a cathode piece.

[0093] In an embodiment of the present application, at the end stage of winding, the anode sheet will continue to be wound at least one more circle at the end of winding of the cathode sheet, so that the cathode sheet can be wrapped by the anode sheet.

[0094] In an embodiment of the present application, the outermost circle of the first pole piece 11 wraps the outermost circle of the second pole piece 12, the first pole piece 11 is set as the anode piece, and the second pole piece 12 is set as the cathode piece, that is, the anode piece wraps the cathode piece. The lithium ions generated by the cathode can be more fully and orderly embedded in the vacant positions of the anode, which helps to improve the overall capacity of the battery cell and the stability of charging and discharging, and improve the reliability of the battery cell.

[0095] According to some embodiments of the present application, the ratio of the thickness D1 of the inner ring diaphragm 21 to the thickness D2 of the outer ring diaphragm 22 is greater than or equal to 0.2 and less than or equal to 0.95.

[0096] According to some embodiments of the present application, the ratio of the thickness D1 of the inner ring diaphragm 21 to the thickness D2 of the outer ring diaphragm 22 is greater than or equal to 0.3 and less than or equal to 0.85.

[0097] According to some embodiments of the present application, the ratio of the thickness D1 of the inner ring diaphragm 21 to the thickness D2 of the outer ring diaphragm 22 is greater than or equal to 0.4 and less than or equal to 0.75.

[0098] Exemplarily, the ratio of the thickness D1 of the inner ring diaphragm 21 to the thickness D2 of the outer ring diaphragm 22 is equal to 0.5; or the ratio of the thickness D1 of the inner ring diaphragm 21 to the thickness D2 of the outer ring diaphragm 22 is equal to 0.6.

[0099] If the ratio of the thickness D1 of the inner ring diaphragm 21 to the thickness D2 of the outer ring diaphragm 22 is too small, there are two situations: the thickness D1 of the inner ring diaphragm 21 is smaller, or the thickness D2 of the outer ring diaphragm 22 is larger. If the thickness D1 of the inner ring diaphragm 21 is smaller, the mechanical strength of the inner ring diaphragm 21 is reduced, and the physical barrier effect of the inner ring diaphragm 21 will be weakened. During the battery charging and discharging process, micro short circuits or even direct short circuits between the positive and negative electrodes are prone to occur. If the thickness D2 of the outer ring diaphragm 22 is larger, the outer ring diaphragm 22 will produce a certain resistance to the transmission of lithium ions, etc., resulting in a slower charging and discharging process of the battery, a lower charging and discharging efficiency of the battery, and at the same time, it will increase the volume of the battery cell and reduce the energy density of the battery cell.

[0100] If the ratio of the thickness D1 of the inner diaphragm 21 to the thickness D2 of the outer diaphragm 22 is too large, there are two situations: the thickness D1 of the inner diaphragm 21 is larger, or the thickness D2 of the outer diaphragm 22 is smaller. If the thickness D1 of the inner diaphragm 21 is larger, the thickness D2 of the outer diaphragm 22 will be larger, which will reduce the energy density of the battery cell. If the thickness D2 of the outer diaphragm 22 is smaller, the thickness D2 of the inner diaphragm 21 will be smaller, which is prone to micro short circuits or even direct short circuits between the positive and negative electrodes.

[0101] In the embodiment of the present application, the ratio of the thickness D1 of the inner ring diaphragm 21 to the thickness D2 of the outer ring diaphragm 22 is limited within the above range, which can improve the safety of the battery while reducing the impact on the energy density of the battery cell.

[0102] According to some embodiments of the present application, see Figure 3 For the inner ring diaphragm 21 , the coating layer 26 is located on one side surface of the base film 25 ; for the outer ring diaphragm 22 , the coating layer 26 is located on both side surfaces of the base film 25 .

[0103] In the embodiment of the present application, the thickness of the coating layer 26 located on the same side surface of the base film 25 can be equal or different.

[0104] In the embodiment of the present application, two coating layers 26 are provided on the outer ring diaphragm 22, and there is no need to change the manufacturing process of the coating layer 26 of the inner ring diaphragm 21, thereby simplifying the manufacturing process.

[0105] According to some embodiments of the present application, the thickness of the coating layer 26 satisfies at least one of the following conditions: for the inner ring diaphragm 21, the thickness D3 of the coating layer 26 is greater than or equal to 1 μm (micrometer) and less than or equal to 5 μm; for the outer ring diaphragm 22, the thickness D4 of the coating layer 26 located on one side surface of the base film 25 is greater than or equal to 4 μm and less than or equal to 10 μm.

[0106] In the embodiment of the present application, the thickness of the coating layer 26 may satisfy any one of the above conditions or two of the above conditions.

[0107] In the embodiment of the present application, the thickness of the coating layer 26 refers to the thickness of one layer of the coating layer 26 .

[0108] For example, for the inner ring diaphragm 21, the thickness D3 of the coating layer 26 is equal to 3 μm; or the thickness D3 of the coating layer 26 is equal to 4.5 μm. For the outer ring diaphragm 22, the thickness D4 of the coating layer 26 is equal to 6 μm; or the thickness D4 of the coating layer 26 is equal to 7.5 μm.

[0109] In an embodiment of the present application, the thickness of the coating layer 26 in the inner ring diaphragm 21 and the outer ring diaphragm 22 are respectively limited, and the thickness of the inner ring diaphragm 21 and the thickness of the outer ring diaphragm 22 can be adjusted by adjusting the thickness of the coating layer 26 respectively.

[0110] According to some embodiments of the present application, the material of the base film 25 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, a polyolefin material, and a polyolefin modified material.

[0111] The above materials have good liquid absorption and retention capabilities, and can adsorb and retain a certain amount of electrolyte, so that the electrolyte is evenly distributed inside the battery, providing a good dielectric environment for ion conduction, which helps to improve the efficiency and uniformity of ion transmission inside the battery, thereby improving the overall performance and stability of the battery.

[0112] According to some embodiments of the present application, the coating layer 26 includes a ceramic coating.

[0113] The ceramic coating enhances the high temperature resistance of the isolation membrane 20 , improves the thermal stability of the isolation membrane 20 , improves the thermal shrinkage of the isolation membrane 20 , and can also enhance the puncture resistance of the isolation membrane 20 , thereby improving the reliability of the battery.

[0114] According to some embodiments of the present application, the material of the ceramic coating includes at least one of aluminum oxide, boehmite, silicon dioxide, zirconium oxide, and titanium oxide.

[0115] The above materials are relatively common ceramic coating materials, which are easy to obtain and reduce production costs.

[0116] According to some embodiments of the present application, the porosity of the coating layer 26 is greater than or equal to 40% and less than or equal to 80%.

[0117] Exemplarily, the porosity of the coating layer 26 is equal to 50%; or the porosity of the coating layer 26 is equal to 60%; or the porosity of the coating layer 26 is equal to 70%.

[0118] The porosity of the coating layer 26 is limited to be greater than or equal to 40%. The coating layer 26 can provide a smooth transmission channel for lithium ions, so that lithium ions can move between the electrodes on both sides of the separator through these pores, thereby improving the charge and discharge performance and charge and discharge efficiency of the battery. The porosity of the coating layer 26 is limited to be less than or equal to 80%, so that the strength and isolation function of the separator 20 will not be reduced due to excessive porosity, and the influence on the adsorption of electrolyte by the separator 20 is reduced.

[0119] According to some embodiments of the present application, see Figure 3 The isolation film 20 further includes two adhesive layers 27 , and the base film 25 and the coating layer 26 are located between the two adhesive layers 27 .

[0120] In an embodiment of the present application, for the inner ring diaphragm 21 , one adhesive layer 27 contacts the base film 25 , and another adhesive layer 27 contacts the coating layer 26 ; for the outer ring diaphragm 22 , both adhesive layers 27 contact the coating layer 26 .

[0121] In the embodiment of the present application, the adhesive layer 27 can adhere to the pole piece 10 to improve the firmness of the connection between the isolation film 20 and the pole piece 10 .

[0122] According to some embodiments of the present application, the material of the adhesive layer 27 includes at least one of polyvinylidene fluoride homopolymer, polyvinylidene fluoride copolymer, polyvinyl chloride, polyethylene oxide and polymethacrylic acid resin.

[0123] The above material has good adhesive properties and can improve the adhesive properties of the adhesive layer 27 . Meanwhile, the above material is easy to obtain, thus reducing the cost of manufacturing the isolation film 20 .

[0124] According to some embodiments of the present application, a thickness D5 of the adhesive layer 27 is greater than or equal to 1 μm and less than or equal to 10 μm.

[0125] Exemplarily, the thickness D5 of the adhesive layer 27 is equal to 3 μm; or the thickness D5 of the adhesive layer 27 is equal to 5 μm; or the thickness D5 of the adhesive layer 27 is equal to 7 μm; or the thickness D5 of the adhesive layer 27 is equal to 9 μm.

[0126] In an embodiment of the present application, the thickness D5 of the bonding layer 27 is limited to be greater than or equal to 1 μm, so that the isolation film 20 has sufficient bonding layer 27 for bonding the electrode 10; the thickness D5 of the bonding layer 27 is limited to be less than or equal to 10 μm, reducing the influence of the excessive thickness of the bonding layer 27 on the transmission of lithium ions.

[0127] According to some embodiments of the present application, the adhesive force of the adhesive layer 27 is greater than or equal to 5N (Newton) and less than or equal to 25N.

[0128] Exemplarily, the adhesive force of adhesive layer 27 is equal to 8N; or the adhesive force of adhesive layer 27 is equal to 10N; or the adhesive force of adhesive layer 27 is equal to 12N; or the adhesive force of adhesive layer 27 is equal to 15N; or the adhesive force of adhesive layer 27 is equal to 20N; or the adhesive force of adhesive layer 27 is equal to 22N.

[0129] In an embodiment of the present application, the bonding force of the bonding layer 27 is limited to be greater than or equal to 5N, so that the bonding layer 27 has sufficient bonding force to bond the electrode 10; if the bonding force of the bonding layer 27 is too strong, the contact between the isolation membrane 20 and the electrode 10 may be too close, resulting in the transmission of lithium ions at the interface between the isolation membrane 20 and the electrode 10 being hindered. The bonding force of the bonding layer 27 is limited to be less than or equal to 25N, so as to reduce the influence of the bonding layer 27 on the transmission of lithium ions.

[0130] According to some embodiments of the present application, Figure 4 This is a cross-sectional view of another electrode assembly provided in an embodiment of the present application. Figure 4 The electrode assembly 200 has a curved region 201 and a straight region 202 . The electrode piece 10 includes a first sub-electrode piece 13 and a second sub-electrode piece 14 . The first sub-electrode piece 13 is located in the curved region 201 , and the second sub-electrode piece 14 is at least located in the straight region 202 .

[0131] Figure 5 This is a comparison diagram of the cross-sectional view of a first sub-pole piece and a second sub-pole piece provided in an embodiment of the present application. Figure 5 , the thickness D6 of the first sub-pole sheet 13 is less than the thickness D7 of the second sub-pole sheet 14 .

[0132] In the embodiment of the present application, for the pole pieces 10 with the same polarity, along the winding direction of the electrode assembly 200 , the first sub-pole piece 13 and the second sub-pole piece 14 are adjacent.

[0133] In the embodiment of the present application, the wound electrode assembly 200 may include two curved regions 201 and one straight region 202, the two curved regions 201 are respectively located on opposite sides of the straight region 202, and the two curved regions 201 are adjacent to the straight region 202, so that the cross-sectional view of the electrode assembly 200 presents a shape similar to a runway. Of course, in other implementations, the electrode assembly 200 may include other numbers of curved regions 201 and straight regions 202.

[0134] It should be noted that the straight region 202 only has a smaller curvature than the curved region 201 , which does not mean that the straight region 202 is completely straight.

[0135] In the embodiment of the present application, the first sub-pole piece 13 is located in the curved region 201 , the second sub-pole piece 14 can be located in the straight region 202 or in the curved region 201 , and the pole pieces 10 located in the curved region 201 are not necessarily all the first sub-pole pieces 13 .

[0136] During the charge and discharge cycle of the battery cell 100, the distance between the pole pieces 10 will gradually increase, causing the battery cell 100 to expand outward, and the pole pieces 10 will also be squeezed. The stress on the pole piece 10 located in the curved area 201 is greater than the stress on the pole piece 10 located in the straight area 202. During the long-term use of the battery cell 100, the stress on the pole piece 10 located in the curved area 201 will gradually accumulate, which may cause the pole piece 10 to rupture, affecting the stability of the battery cell 100.

[0137] In an embodiment of the present application, part of the pole piece 10 located in the bending area 201 is set as a first sub-pole piece 13 with a smaller thickness, and the spacing between the first sub-pole piece 13 and its adjacent pole piece is larger, so that the pole piece 10 located in the bending area 201 has more expansion space, reducing the stress on the pole piece 10 and the possibility of breakage of the pole piece 10, thereby improving the stability and life of the battery cell 100.

[0138] In the embodiment of the present application, it is assumed that a certain section of the pole piece 10 enters the bending area 201 from G and exits the bending area 201 from H, and the portion of the pole piece 10 from G to H is entirely located in the bending area 201. Then, the entire portion of the pole piece 10 from G to H is the first sub-pole piece 13; or a portion of the pole piece 10 from G to H is the first sub-pole piece 13, and the other portion is the second sub-pole piece 14.

[0139] In an embodiment of the present application, a section of the pole piece 10 enters the bending area 201 from G and exits the bending area 201 from H. If the pole piece 10 is unfolded, the direction from G to H is the length direction of the pole piece 10, and the width of the first sub-pole piece 13 between G and H can be equal to the width of the pole piece 10, or the width of the first sub-pole piece 13 between G and H is smaller than the width of the pole piece 10.

[0140] According to some embodiments of the present application, the outermost pole piece 10 of the bending region 201 is the first sub-pole piece 13 .

[0141] In the embodiment of the present application, during the expansion of the battery cell 100, the stress on the pole piece 10 located in the outer circle is greater than the stress on the pole piece 10 located in the inner circle, and the stress on the pole piece 10 located in the curved area 201 is greater than the stress on the pole piece 10 located in the straight area 202. In summary, the stress on the pole piece 10 located in the outermost circle of the curved area 201 is greater than the stress on other pole pieces 10, and the pole piece 10 located in the outermost circle of the curved area 201 is more likely to break.

[0142] Since the stress on the pole piece 10 located in the outermost circle of the bending area 201 is greater than the stress on other pole pieces 10, setting the pole piece 10 in the outermost circle of the bending area 201 as the first sub-pole piece 13 can reduce the stress on the pole piece 10 in the outermost circle of the bending area 201 to a greater extent and reduce the possibility of the pole piece 10 breaking.

[0143] According to some embodiments of the present application, Figure 6 This is a cross-sectional view of another electrode assembly provided in an embodiment of the present application. Figure 6 , the second sub-pole piece 14 is also located in the curved region 201. For the pole piece 10 with the same polarity, the first sub-pole piece 13 located in the curved region 201 has n turns, and there are m turns of the second sub-pole piece 14 between any two adjacent turns of the first sub-pole piece 13 from the first turn of the first sub-pole piece 13 to the (n-1)th turn of the first sub-pole piece 13, and there are k turns of the second sub-pole piece 14 between the (n-1)th turn of the first sub-pole piece 13 and the nth turn of the first sub-pole piece 13. Wherein, m is an integer greater than or equal to 1 and less than or equal to 15, k is an integer less than or equal to m, and n is an integer greater than or equal to 3.

[0144] In the embodiment of the present application, for the pole pieces 10 with the same polarity, the first sub-pole piece 13 located in the bending area 201 has n turns, which means that the first sub-pole piece 13 with the same polarity and located in the same bending area 201 has n turns.

[0145] In the embodiment of the present application, the battery cell 100 includes pole pieces 10 of two polarities, and at least one pole piece 10 of one polarity satisfies the above conditions.

[0146] In the embodiment of the present application, a first sub-pole piece 13 that is less than a full circle in the bending area 201 is also counted as one circle.

[0147] For example, n may be greater than or equal to 3 and less than or equal to 30; and m may be greater than or equal to 5 and less than or equal to 10.

[0148] In an embodiment of the present application, k is an integer less than or equal to m, indicating that for the first sub-pole pieces 13 with the same polarity in the same curved area 201, the number of second sub-pole pieces 14 between the (n-1)th circle of first sub-pole pieces 13 and the nth circle of first sub-pole pieces 13 is less than the number of second sub-pole pieces 14 between any other two adjacent circles of first sub-pole pieces 13.

[0149] Exemplarily, k may be equal to 0, that is, for the first sub-pole pieces 13 with the same polarity in the same bending region 201 , there is no second sub-pole piece 14 between the (n−1)th circle of first sub-pole pieces 13 and the nth circle of first sub-pole pieces 13 .

[0150] As the thickness of the first sub-pole piece 13 decreases, the strength of the first sub-pole piece 13 decreases. In the embodiment of the present application, the first sub-pole pieces 13 are spaced apart in the bending area 201 to reduce the influence of the reduced strength of the first sub-pole piece 13 on the strength of the bending area.

[0151] According to some embodiments of the present application, when the pole piece 10 includes a first pole piece 11 and a second pole piece 12, the portion of the first pole piece 11 located at the outermost circle of the bending area 201 is the first sub-pole piece 13; the portion of the second pole piece 12 located at the outermost circle of the bending area 201 is the first sub-pole piece 13.

[0152] That is, for a pole piece 10 of any polarity, the outermost portion thereof located in the bending region 201 is the first sub-pole piece 13 .

[0153] In the embodiment of the present application, the outermost parts of the first pole piece 11 and the second pole piece 12 are both set as the first sub-pole piece 13, which can reduce the possibility of the first pole piece 11 and the second pole piece 12 being broken.

[0154] Exemplarily, assuming that the first pole piece 11 located in the same bending area 201 has 42 turns, then the first pole pieces 11 located in the 5th, 10th, 15th, 20th, 25th, 30th, 35th, 40th and 42nd turns in the bending area 201 can be the first sub-pole piece 13.

[0155] According to some embodiments of the present application, when the pole piece 10 includes a first pole piece 11 and a second pole piece 12, the first pole piece 11 includes a first sub-pole piece 13 and a second sub-pole piece 14, the second pole piece 12 includes a first sub-pole piece 13 and a second sub-pole piece 14, and the number of turns of the first sub-pole piece 13 in the first pole piece 11 is equal to the number of turns of the first sub-pole piece 13 in the second pole piece 12.

[0156] It can be understood that the portion of the first pole piece 11 with reduced thickness corresponds to the portion of the second pole piece 12 with reduced thickness.

[0157] The pole piece 10 is used to store and transmit lithium ions. The thickness of the first pole piece 13 is less than that of the second pole piece 14. The ability of the first pole piece 13 to store and transmit lithium ions is relatively weak. During the charging and discharging process of the battery cell 100, lithium ions move between the first pole piece 11 and the second pole piece 12. If the ability of a certain part of the first pole piece 11 to store and transmit lithium ions is weakened, even if the second pole piece 12 opposite to it has a strong ability to store and transmit lithium ions, the ability of transmitting lithium ions between the first pole piece 11 and the second pole piece 12 will be weak, that is, the capacity contributed by the first pole piece 11 and the second pole piece 12 is small.

[0158] In the embodiment of the present application, the portion of the first pole sheet 11 with reduced thickness corresponds to the portion of the second pole sheet 12 with reduced thickness. This portion of the first pole sheet 11 and the second pole sheet 12 can provide expansion space and also reduce the impact on the energy density of the battery cell 100.

[0159] According to some embodiments of the present application, see Figure 5 The pole piece 10 includes a current collector 15 and an active material layer 16 , the active material layer 16 is located on at least one side surface of the current collector 15 , and the first sub-pole piece 13 and the second sub-pole piece 14 satisfy one of the following conditions.

[0160] See also Figure 5 The first sub-pole sheet 13 and the second sub-pole sheet 14 both include a current collector 15 and an active material layer 16 , and a thickness D8 of the active material layer 16 of the first sub-pole sheet 13 is less than a thickness D9 of the active material layer 16 of the second sub-pole sheet 14 .

[0161] Figure 7 This is a schematic diagram of an expanded pole piece provided in an embodiment of the present application. Figure 7 The first sub-electrode sheet 13 includes a current collector 15 , and the second sub-electrode sheet 14 includes a current collector 15 and an active material layer 16 .

[0162] The active material is usually coated on the surface of the current collector 15 in the form of powder or slurry. The current collector 15 provides a stable attachment base for the active material, so that the active material can be maintained in a specific position to form a complete electrode structure.

[0163] The active material in the active material layer 16 can reversibly embed and extract lithium ions during the charge and discharge process. During the charge and discharge process of the battery, the active material in the active material layer 16 will undergo an oxidation-reduction reaction. During the electrochemical reaction, electrons can be conducted between the active material particles and between the active material and the current collector 15, so that the electron transmission inside the battery can proceed smoothly, thereby ensuring that the battery can be charged and discharged normally.

[0164] In some embodiments of the present application, the first sub-electrode sheet 13 may not be provided with the active material layer 16. For example, the active material layer 16 may be coated on the second sub-electrode sheet 14 by intermittent coating; or the active material layer 16 may be coated on both the first sub-electrode sheet 13 and the second sub-electrode sheet 14, and then the active material layer 16 on the first sub-electrode sheet 13 may be cleaned by laser cleaning.

[0165] In some other embodiments of the present application, the thickness of the active material layer 16 on the first sub-electrode sheet 13 may be reduced.

[0166] When the thickness of the active material layer 16 on the first sub-electrode sheet 13 is reduced, the active material layer 16 may be provided on one surface of the current collector 15 , or on both surfaces of the current collector 15 .

[0167] The active material layer 16 is made on the surface of the current collector 15 by coating or other processes. Compared with changing the thickness of the current collector 15 , it is more convenient to change the thickness of the active material layer 16 .

[0168] An embodiment of the present application provides a battery device, which includes any one of the above-mentioned battery cells.

[0169] Figure 8Schematic diagram of the exploded structure of the battery device provided for some embodiments of the present application. The battery device 400 includes a box 500 and a battery cell 100, and the battery cell 100 is contained in the box 500. Among them, the box 500 is used to provide a storage space for the battery cell 100, and the box 500 can adopt a variety of structures. In some embodiments, the box 500 may include a first part 501 and a second part 502, and the first part 501 and the second part 502 cover each other, and the first part 501 and the second part 502 jointly define a storage space for accommodating the battery cell 100. The second part 502 can be a hollow structure with one end open, and the first part 501 can be a plate-like structure, and the first part 501 covers the open side of the second part 502, so that the first part 501 and the second part 502 jointly define a storage space; the first part 501 and the second part 502 can also be hollow structures with one side open, and the open side of the first part 501 covers the open side of the second part 502. Of course, the box body 500 formed by the first part 501 and the second part 502 can be in various shapes, such as a cylinder, a cuboid, etc.

[0170] In the battery device 400, there may be multiple battery cells 100, and the multiple battery cells 100 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 100 are both connected in series and in parallel. The multiple battery cells 100 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 100 is accommodated in the box 500; of course, the battery device 400 may also be a battery module formed by connecting multiple battery cells 100 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 500. The battery device 400 may also include other structures, for example, the battery device 400 may also include a busbar component for realizing electrical connection between the multiple battery cells 100.

[0171] Each battery cell 100 may be a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto.

[0172] In the battery device 400 provided in the embodiment of the present application, the possibility of the electrode sheet 10 being broken is reduced, thereby improving the stability and life of the battery device 400.

[0173] An embodiment of the present application provides an electrical device, which includes the above-mentioned battery device 400, and the battery device 400 is used to provide electrical energy.

[0174] The embodiment of the present application provides an electric device using a battery device as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0175] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0176] Fig. 9 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application. The vehicle 1000 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, etc. A battery device 400 is provided inside the vehicle 1000, and the battery device 400 may be provided at the bottom, head or tail of the vehicle 1000. The battery device 400 may be used to power the vehicle 1000, for example, the battery device 400 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 600 and a motor 700, and the controller 600 is used to control the battery device 400 to power the motor 700, for example, for starting, navigating and driving the vehicle 1000.

[0177] In some embodiments of the present application, the battery device 400 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0178] The electrical device provided by the embodiment of the present application has a higher lifespan and stability.

[0179] An embodiment of the present application provides an energy storage device, which includes the battery device in the above embodiment, and the battery device is used to store electrical energy.

[0180] The energy storage device may be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system.

[0181] The energy storage device provided in the embodiment of the present application has a higher lifespan and stability.

[0182] The embodiment of the present application provides a battery cell, wherein the battery cell 100 includes a pole piece 10 and a separator 20, wherein the pole piece 10 and the separator 20 are wound to form an electrode assembly 200, and the separator 20 is located between adjacent circles of pole pieces 10. The outermost circle of the electrode assembly 200 is the separator 20, and the portion of the separator 20 wound at least one circle from the beginning of the separator to the end of the separator is the inner circle separator 21, and the portion of the separator 20 wound at least one circle from the end of the separator to the beginning of the separator is the outer circle separator 22. The ratio of the thickness D1 of the inner circle separator 21 to the thickness D2 of the outer circle separator 22 is greater than or equal to 0.4 and less than or equal to 0.75.

[0183] The pole piece 10 includes a first pole piece 11 and a second pole piece 12, and the isolation film 20 includes a first diaphragm 23 and a second diaphragm 24. The first pole piece 11, the first diaphragm 23, the second pole piece 12 and the second diaphragm 24 are stacked and wound in sequence to form an electrode assembly 200. The outermost circle of the electrode assembly 200 is the first diaphragm 23, and the outermost circle of the first pole piece 11 wraps the outermost circle of the second pole piece 12. The first diaphragm 23 includes an inner circle diaphragm 21 and an outer circle diaphragm 22. The second diaphragm 24 includes an inner circle diaphragm 21 and an outer circle diaphragm 22. The first pole piece 11 is an anode piece, and the second pole piece 12 is a cathode piece. The inner circle diaphragm 21 and the outer circle diaphragm 22 located on the same isolation film 20 are adjacent to each other.

[0184] The portion of the second pole piece 12 wound one circle from the second pole piece terminal to the second pole piece starting end is the outer ring second pole piece 121 , and the side of the outer ring diaphragm 22 close to the starting end of the isolation membrane is opposite to the side of the outer ring second pole piece 121 close to the starting end of the second pole piece.

[0185] The isolation film 20 includes a base film 25 and a coating layer 26. The coating layer 26 is located on at least one side surface of the base film 25, and the thickness D3 of the coating layer 26 of the inner ring diaphragm 21 is less than the thickness D4 of the coating layer 26 of the outer ring diaphragm 22. For the inner ring diaphragm 21, the coating layer 26 is located on one side surface of the base film 25; for the outer ring diaphragm 22, the coating layer 26 is located on both sides of the base film 25. For the inner ring diaphragm 21, the thickness of the coating layer 26 is greater than or equal to 1μm and less than or equal to 5μm; for the outer ring diaphragm 22, the thickness of the coating layer 26 located on one side surface of the base film 25 is greater than or equal to 4μm and less than or equal to 10μm.

[0186] The material of the base film 25 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyolefin materials and polyolefin modified materials. The coating layer 26 includes a ceramic coating. The material of the ceramic coating includes at least one of aluminum oxide, boehmite, silicon dioxide, zirconium oxide and titanium oxide. The porosity of the coating layer 26 is greater than or equal to 40% and less than or equal to 80%. The isolation film 20 also includes two adhesive layers 27, and the base film 25 and the coating layer 26 are located between the two adhesive layers 27. The material of the adhesive layer 27 includes at least one of polyvinylidene fluoride homopolymer, polyvinylidene fluoride copolymer, polyvinyl chloride, polyethylene oxide and polymethacrylic acid resin. The thickness D5 of the adhesive layer 27 is greater than or equal to 1μm and less than or equal to 10μm. The adhesive force of the adhesive layer 27 is greater than or equal to 5N and less than or equal to 25N.

[0187] The electrode assembly 200 has a curved region 201 and a straight region 202. The electrode piece 10 includes a first sub-electrode piece 13 and a second sub-electrode piece 14, the first sub-electrode piece 13 is located in the curved region 201, and the second sub-electrode piece 14 is located in the straight region 202 and the curved region 201. The thickness D5 of the first sub-electrode piece 13 is less than the thickness D6 of the second sub-electrode piece 14. The outermost portion of the first electrode piece 11 located in the curved region 201 is the first sub-electrode piece 13; the outermost portion of the second electrode piece 12 located in the curved region 201 is the first sub-electrode piece 13.

[0188] For the pole piece 10 with the same polarity, the first sub-pole piece 13 located in the curved area 201 has n turns, and between any two adjacent turns of the first sub-pole piece 13 from the first turn of the first sub-pole piece 13 to the (n-1)th turn of the first sub-pole piece 13 there are m turns of the second sub-pole piece 14, and between the (n-1)th turn of the first sub-pole piece 13 and the nth turn of the first sub-pole piece 13 there are k turns of the second sub-pole piece 14. Wherein, m is an integer greater than or equal to 1 and less than or equal to 15, k is an integer less than or equal to m, and n is an integer greater than or equal to 3.

[0189] The first pole piece 11 includes a first sub-pole piece 13 and a second sub-pole piece 14 , and the second pole piece 12 includes a first sub-pole piece 13 and a second sub-pole piece 14 . The number of turns of the first sub-pole piece 13 in the first pole piece 11 is equal to the number of turns of the first sub-pole piece 13 in the second pole piece 12 .

[0190] The pole piece 10 includes a current collector 15 and an active material layer 16 , the first sub-pole piece 13 includes a current collector 15 , and the second sub-pole piece 14 includes a current collector 15 and an active material layer 16 .

[0191] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: The battery cell (100) comprises a pole piece (10) and a separator (20), the pole piece (10) and the separator (20) being wound to form an electrode assembly (200), the separator (20) being located between adjacent turns of the pole piece (10); The outermost circle of the electrode assembly (200) is the separator (20), the portion of the separator (20) wound at least one circle from the separator start end to the separator end end is the inner separator (21), and the portion of the separator (20) wound at least one circle from the separator end end to the separator start end is the outer separator (22); The isolation film (20) comprises a base film (25) and a coating layer (26), wherein the coating layer (26) is located on at least one side surface of the base film (25), and the thickness of the coating layer (26) of the inner ring diaphragm (21) is smaller than the thickness of the coating layer (26) of the outer ring diaphragm (22).

2. The battery cell according to claim 1, characterized in that: The pole piece (10) comprises a first pole piece (11) and a second pole piece (12); the isolation film (20) comprises a first diaphragm (23) and a second diaphragm (24); the first pole piece (11), the first diaphragm (23), the second pole piece (12) and the second diaphragm (24) are sequentially stacked and wound to form the electrode assembly (200); the outermost circle of the electrode assembly (200) is the first diaphragm (23); and the outermost circle of the first pole piece (11) wraps the outermost circle of the second pole piece (12); The first diaphragm (23) comprises the inner ring diaphragm (21) and the outer ring diaphragm (22).

3. The battery cell according to claim 2, characterized in that: The second diaphragm (24) comprises the inner ring diaphragm (21) and the outer ring diaphragm (22).

4. The battery cell according to claim 2, characterized in that: The portion of the second pole piece (12) wound one circle from the second pole piece terminal to the second pole piece starting end is the outer ring second pole piece (121), and the side of the outer ring diaphragm (22) close to the starting end of the isolation membrane is opposite to the side of the outer ring second pole piece (121) close to the starting end of the second pole piece.

5. The battery cell according to claim 4, characterized in that: The inner ring diaphragm (21) and the outer ring diaphragm (22) located on the same isolation diaphragm (20) are adjacent to each other.

6. The battery cell according to claim 2, characterized in that: The first pole piece (11) is an anode piece, and the second pole piece (12) is a cathode piece.

7. The battery cell according to any one of claims 1 to 6, characterized in that: The ratio of the thickness of the inner ring diaphragm (21) to the thickness of the outer ring diaphragm (22) is greater than or equal to 0.2 and less than or equal to 0.

95.

8. The battery cell according to claim 7, characterized in that: The ratio of the thickness of the inner ring diaphragm (21) to the thickness of the outer ring diaphragm (22) is greater than or equal to 0.3 and less than or equal to 0.

85.

9. The battery cell according to claim 8, characterized in that: The ratio of the thickness of the inner ring diaphragm (21) to the thickness of the outer ring diaphragm (22) is greater than or equal to 0.4 and less than or equal to 0.

75.

10. The battery cell according to any one of claims 1 to 6, characterized in that: For the inner ring diaphragm (21), the coating layer (26) is located on one side surface of the base film (25); For the outer ring diaphragm (22), the coating layer (26) is located on both side surfaces of the base film (25).

11. The battery cell according to claim 10, characterized in that: The thickness of the coating layer (26) satisfies at least one of the following conditions: For the inner ring diaphragm (21), the coating layer (26) has a thickness greater than or equal to 1 μm and less than or equal to 5 μm; For the outer ring diaphragm (22), the coating layer (26) located on one side surface of the base film (25) has a thickness greater than or equal to 4 μm and less than or equal to 10 μm.

12. The battery cell according to any one of claims 1 to 6, characterized in that: The material of the base film (25) includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyolefin material and polyolefin modified material.

13. The battery cell according to any one of claims 1 to 6, characterized in that: The coating layer (26) includes a ceramic coating.

14. The battery cell according to claim 13, characterized in that: The material of the ceramic coating includes at least one of aluminum oxide, boehmite, silicon dioxide, zirconium oxide and titanium oxide.

15. The battery cell according to any one of claims 1 to 6, characterized in that: The porosity of the coating layer (26) is greater than or equal to 40% and less than or equal to 80%.

16. The battery cell according to any one of claims 1 to 6, characterized in that: The isolation film (20) further comprises two adhesive layers (27), and the base film (25) and the coating layer (26) are located between the two adhesive layers (27).

17. The battery cell according to claim 16, characterized in that: The material of the adhesive layer (27) includes at least one of polyvinylidene fluoride homopolymer, polyvinylidene fluoride copolymer, polyvinyl chloride, polyethylene oxide and polymethacrylic acid resin.

18. The battery cell according to claim 16, characterized in that: The thickness of the adhesive layer (27) is greater than or equal to 1 μm and less than or equal to 10 μm.

19. The battery cell according to claim 16, characterized in that: The adhesive force of the adhesive layer (27) is greater than or equal to 5N and less than or equal to 25N.

20. The battery cell according to any one of claims 1 to 6, characterized in that: The electrode assembly (200) has a curved region (201) and a straight region (202); the electrode piece (10) comprises a first sub-electrode piece (13) and a second sub-electrode piece (14); the first sub-electrode piece (13) is located in the curved region (201), and the second sub-electrode piece (14) is at least located in the straight region (202); The thickness of the first sub-pole piece (13) is smaller than the thickness of the second sub-pole piece (14).

21. The battery cell according to claim 20, characterized in that: The outermost pole piece (10) of the bending area (201) is the first sub-pole piece (13).

22. The battery cell according to claim 21, characterized in that: The second sub-pole piece (14) is also located in the bending region (201); for the pole pieces (10) with the same polarity, the first sub-pole piece (13) located in the bending region (201) has n turns, and between any two adjacent turns of the first sub-pole piece (13) from the first turn of the first sub-pole piece (13) to the (n-1)th turn of the first sub-pole piece (13) there are m turns of the second sub-pole piece (14), and between the (n-1)th turn of the first sub-pole piece (13) and the nth turn of the first sub-pole piece (13) there are k turns of the second sub-pole piece (14), wherein m is an integer greater than or equal to 1 and less than or equal to 15, k is an integer less than or equal to m, and n is an integer greater than or equal to 3.

23. The battery cell according to claim 21 or 22, characterized in that: In the case where the pole piece (10) comprises a first pole piece (11) and a second pole piece (12), the outermost portion of the first pole piece (11) located in the curved area (201) is the first sub-pole piece (13); The outermost portion of the second pole piece (12) located in the curved area (201) is the first sub-pole piece (13).

24. The battery cell according to claim 20, characterized in that: In the case where the pole piece (10) comprises a first pole piece (11) and a second pole piece (12), the first pole piece (11) comprises the first sub-pole piece (13) and the second sub-pole piece (14), the second pole piece (12) comprises the first sub-pole piece (13) and the second sub-pole piece (14), and the number of turns of the first sub-pole piece (13) in the first pole piece (11) is equal to the number of turns of the first sub-pole piece (13) in the second pole piece (12).

25. The battery cell according to claim 20, characterized in that: The pole piece (10) comprises a current collector (15) and an active material layer (16), wherein the active material layer (16) is located on at least one side surface of the current collector (15), and the first sub-pole piece (13) and the second sub-pole piece (14) satisfy one of the following conditions: The first sub-pole sheet (13) comprises the current collector (15), and the second sub-pole sheet (14) comprises the current collector (15) and the active material layer (16); The first sub-pole sheet (13) and the second sub-pole sheet (14) both comprise the current collector (15) and the active material layer (16), and the thickness of the active material layer (16) of the first sub-pole sheet (13) is smaller than the thickness of the active material layer (16) of the second sub-pole sheet (14).

26. A battery device, characterized in that: The battery device comprises the battery cell (100) according to any one of claims 1 to 25.

27. An electrical device, characterized in that: The electrical device comprises the battery device as claimed in claim 26, and the battery device is used to provide electrical energy.

28. An energy storage device, characterized in that: The energy storage device comprises a battery device as claimed in claim 26, wherein the battery device is used to store electrical energy.

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