Battery cell, battery device, power consumption device, and energy storage device

Abstract

The present application provides a battery cell, a battery device, an electrical device, and an energy storage device, belonging to the technical field of batteries. The battery cell includes a pole piece and a separator. The pole piece and the separator are wound to form an electrode assembly, and the separator is located between adjacent turns of the pole piece. The outermost circle of the electrode assembly is the separator. The part of the separator that winds at least one turn from the separator start end to the separator terminal end is the inner circle separator, and the part of the separator that winds at least one turn from the separator terminal end to the separator start end is the outer circle separator. 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. The outer circle separator wraps the outermost circle of the pole piece. 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 on the outer circle pole piece, reducing the possibility of pole piece fracture, and improving the stability and lifespan of the battery cell.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and particularly 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 keys to the sustainable development of society. 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 related to its development.

[0003] During the charge and discharge process of the battery, the battery cell will expand. With the charge and discharge cycles of the battery, the stress inside the battery cell gradually accumulates, which may cause the pole piece to break, affecting the stability and lifespan of the battery. Summary of the Invention

[0004] This application aims to solve at least one of the technical problems existing in the background art. For this reason, one objective of this application is to provide a battery cell, a battery device, an electrical device, and an energy storage device to improve the stability and lifespan of the battery.

[0005] An embodiment of the first aspect of this application provides a battery cell. The battery cell includes a pole piece and a separator. The pole piece and the separator are wound to form an electrode assembly, and the separator is located between adjacent turns of the pole piece; the outermost circle of the electrode assembly is the separator. The part of the separator that winds at least one turn from the separator start end to the separator end is the inner circle separator, and the part of the separator that winds at least one turn from the separator end to the separator start end is the outer circle separator; wherein, the separator includes a base film and a coating layer, the coating layer is located on at least one 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 this application, the outermost circle of the electrode assembly is the outer circle separator, and the outer circle separator wraps the outermost circle of the pole piece. The stress on the pole piece will be transmitted to the outer circle separator. Increasing the thickness of the coating layer of the outer circle separator makes the thickness of the outer circle separator increase, and the strength and toughness of the outer circle separator increase. The outer circle separator can absorb more stress, thereby reducing the stress on the outer circle pole piece and reducing the possibility of the pole piece breaking, and improving the stability and lifespan of the battery cell.

[0007] In some embodiments, the electrode tab includes a first electrode tab and a second electrode tab, and the separator includes a first separator and a second separator. The first electrode tab, the first separator, the second electrode tab, and the second separator are stacked and wound in sequence to form an electrode assembly. The outermost layer of the electrode assembly is the first separator, and the outermost layer of the first electrode tab wraps the outermost layer of the second electrode tab; the first separator includes an inner separator and an outer separator. By providing two layers of separators, namely the first separator and the second separator, during the winding process, any adjacent two layers of the first electrode tab and the second electrode tab can be separated by one of the first separator and the second separator, improving the stability of the battery cell. Since the first separator is located in the outermost layer, whether it is the stress of the first electrode tab or the stress of the second electrode tab, it will be transmitted to the first separator. By providing an outer separator on the first separator, the outer separator of the first separator can absorb more stress, reduce the stress of the electrode tab, reduce the possibility of the electrode tab breaking, and improve the stability and lifespan of the battery cell.

[0008] In some embodiments, the second separator includes an inner separator and an outer separator. There is stress in both the first electrode tab and the second electrode tab. The first electrode tab transmits stress to the first separator, and the second electrode tab transmits stress to the second separator. By providing outer separators on both the first separator and the second separator, the outer separators of both the first separator and the second separator can absorb the stress of the first electrode tab and the second electrode tab, reduce the stress of the first electrode tab and the second electrode tab, reduce the possibility of the first electrode tab and the second electrode tab breaking, and improve the stability and lifespan of the battery cell.

[0009] In some embodiments, the part of the second electrode tab that winds one circle from the terminal of the second electrode tab to the beginning of the second electrode tab is the outer second electrode tab, and the side of the outer separator close to the beginning of the separator is opposite to the side of the outer second electrode tab close to the beginning of the second electrode tab. The side of the outer separator close to the beginning of the separator being opposite to the side of the outer second electrode tab close to the beginning of the second electrode tab can enable the outer separator to cover the outermost layer of the electrode tab, and the outer separator can absorb the stress of the outermost layer of the electrode tab, reducing the stress of the electrode tab.

[0010] In some embodiments, the inner separator and the outer separator on the same separator are adjacent. The part of the separator excluding the outer separator is the inner separator, and the separator only includes two different thicknesses, making the process of manufacturing the separator simpler and simplifying the manufacturing process.

[0011] In some embodiments, the first electrode tab is the anode tab and the second electrode tab is the cathode tab. The outermost layer of the first electrode tab wraps the outermost layer of the second electrode tab. By setting the first electrode tab as the anode tab and the second electrode tab as the cathode tab, that is, the anode tab wraps the cathode tab, the lithium ions generated by the cathode can be more fully and orderly embedded into the vacant positions of the anode, which helps to improve the overall capacity and charge-discharge stability of the battery cell and improve the reliability of the battery cell.

[0012] 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 0.2 and less than or equal to 0.95.

[0013] 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 0.3 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 separator includes: a base film; a coating layer located on at least one surface of the base film; wherein, the thickness of the coating layer of the inner diaphragm is less than the thickness of the coating layer of the outer diaphragm. The coating layer is made on the surface of the base film by coating or other processes. Compared with changing the thickness of the base film, it is more convenient to change the thickness of the coating layer.

[0016] In some embodiments, the coating layer is located on one surface of the base film; for the outer diaphragm, the coating layer is located on both surfaces of the base film. Setting two coating layers on the outer diaphragm does not require changing the manufacturing process of the coating layer of the inner diaphragm, 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 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 diaphragm, the thickness of the coating layer located on one surface of the base film is greater than or equal to 4 μm and less than or equal to 10 μm. By respectively limiting the thickness of the coating layer in the inner diaphragm and the outer diaphragm, the thickness of the inner diaphragm and the outer diaphragm can be adjusted by respectively adjusting the thickness of the coating layer.

[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 adsorb and retain a certain amount of electrolyte, make the electrolyte evenly distributed inside the battery, provide a good medium environment for ion conduction, help improve the efficiency and uniformity of ion transport inside the battery, and thus enhance the overall performance and stability of the battery.

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

[0020] In some embodiments, the material of the ceramic coating includes at least one of alumina, boehmite, silica, zirconia, and titanium oxide. The above materials are relatively common ceramic coating materials, which are easy to obtain and reduce the manufacturing cost.

[0021] In some embodiments, the porosity of the coating layer is greater than or equal to 40% and less than or equal to 80%. By defining that the porosity of the coating layer is greater than or equal to 40%, the coating layer can provide a smooth transmission channel for lithium ions, enabling lithium ions to move between the electrodes on both sides of the separator through these pores, thereby improving the charge-discharge performance and efficiency of the battery. By defining that the porosity of the coating layer is less than or equal to 80%, the strength and isolation function of the separator will not be reduced due to excessive porosity, and at the same time, the influence on the electrolyte adsorption of the separator is reduced.

[0022] In some embodiments, the separator 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 electrode tabs, improving the firmness of the connection between the separator and the electrode tabs.

[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, which can improve the adhesive performance of the adhesive layer. At the same time, the above materials are easy to obtain, reducing the cost of manufacturing the separator.

[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. By defining that the thickness of the adhesive layer is greater than or equal to 1 μm, the separator has a sufficient adhesive layer for bonding the electrode tabs; by defining that the thickness of the adhesive layer is less than or equal to 10 μm, the influence on the transmission of lithium ions due to the too large thickness of the adhesive layer is reduced.

[0025] In some embodiments, the adhesive force of the adhesive layer is greater than or equal to 5 N and less than or equal to 25 N. By defining that the adhesive force of the adhesive layer is greater than or equal to 5 N, the adhesive layer has sufficient adhesive force to bond the electrode tabs; if the adhesive force of the adhesive layer is too strong, the contact between the separator and the electrode tabs may be too tight, resulting in the hindrance of lithium ion transmission at the interface between the separator and the electrode tabs. By defining that the adhesive force of the adhesive layer is less than or equal to 25 N, the influence of the adhesive layer on lithium ion transmission is reduced.

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

[0027] In some embodiments, the outermost electrode tab in the bent region is the first sub-electrode tab. Since the stress on the outermost electrode tab in the bent region is greater than that on other electrode tabs, setting the outermost electrode tab in the bent region as the first sub-electrode tab can more greatly reduce the stress on the outermost electrode tab in the bent region and reduce the possibility of the electrode tab breaking.

[0028] In some embodiments, the second sub-electrode tab is also located in the bent region. For electrode tabs with the same polarity, there are n turns of the first sub-electrode tab in the bent region. There are m turns of the second sub-electrode tab between any two adjacent turns of the first sub-electrode tab from the first turn of the first sub-electrode tab to the (n - 1)th turn of the first sub-electrode tab, and there are k turns of the second sub-electrode tab between the (n - 1)th turn of the first sub-electrode tab and the nth turn of the first sub-electrode tab, where 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. Since the thickness of the first sub-electrode tab decreases, the strength of the first sub-electrode tab will decrease. In the embodiments of the present application, the first sub-electrode tabs are arranged at intervals in the bent region to reduce the influence on the strength of the bent region caused by the decrease in the strength of the first sub-electrode tab.

[0029] In some embodiments, when the electrode tab includes a first electrode tab and a second electrode tab, the part of the first electrode tab located in the outermost circle of the bent region is the first sub-electrode tab; the part of the second electrode tab located in the outermost circle of the bent region is the first sub-electrode tab. By setting the outermost parts of both the first electrode tab and the second electrode tab as the first sub-electrode tabs, the possibility of the first electrode tab and the second electrode tab breaking can be reduced.

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

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

[0032] An embodiment of the 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 solutions of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically described below. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0037] Figure 1 It is a schematic structural diagram of a battery cell provided by an embodiment of the present application;

[0038] Figure 2 For Figure 1 It is an interface schematic diagram of the A-A plane of the electrode assembly in

[0039] Figure 3 It is a comparison diagram of cross-sectional views of an inner ring separator and an outer ring separator provided by an embodiment of the present application;

[0040] Figure 4 It is a cross-sectional view of another electrode assembly provided by an embodiment of the present application;

[0041] Figure 5 It is a comparison diagram of cross-sectional views of a first sub-electrode tab and a second sub-electrode tab provided by an embodiment of the present application;

[0042] Figure 6 A cross-sectional view of another electrode assembly provided by an embodiment of the present application;

[0043] Figure 7 An unfolded schematic diagram of a pole piece provided by an embodiment of the present application;

[0044] Figure 8 A schematic exploded view of a battery device provided by some embodiments of the present application;

[0045] Figure 9 A schematic structural diagram of a vehicle provided by some embodiments of the present application.

[0046] Explanation of reference numerals:

[0047] 10, pole piece; 11, first pole piece; 12, second pole piece; 121, outer ring second pole piece; 13, first sub-pole piece; 14, second sub-pole piece; 15, current collector; 16, active material layer; 20, separator; 21, inner ring separator; 22, outer ring separator; 23, first separator; 24, second separator; 25, base film; 26, coating layer; 27, adhesive layer; 100, battery cell; 200, electrode assembly; 201, bending region; 202, straight region; 203, main body; 204, tab; 300, housing; 301, end cap; 311, electrode terminal; 312, pressure relief mechanism; 313, adapter plate; 302, shell; 400, battery device; 500, box body; 501, first part; 502, second part; 600, controller; 700, motor; 1000, vehicle. Detailed implementation manners

[0048] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above accompanying drawings are intended to cover non-exclusive inclusion.

[0050] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is more than two, unless otherwise specifically defined.

[0051] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The phrase appearing at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0052] In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0053] In the description of the embodiments of the present application, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0054] In the description of the embodiments of the present application, technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0055] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside 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 specific circumstances.

[0056] At present, from the perspective of the development of the market situation, rechargeable batteries are more and more widely used. Rechargeable batteries are not only applied to energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in various electronic devices, such as electric vehicles, electric motorcycles, electric cars and other electric transportation tools, as well as military equipment and aerospace and other fields. With the continuous expansion of the application fields of rechargeable batteries, the market demand is also continuously increasing.

[0057] During the charge and discharge cycle of the battery, the battery cell will expand, and the electrode plates of the battery cell will be squeezed. As the number of charge and discharge cycles of the battery increases, the stress on the electrode plates 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 outermost electrode plate is the greatest, making the outermost electrode plate prone to breakage, affecting the stability and life of the battery.

[0058] An embodiment of the present application provides a battery cell. The battery cell includes electrode plates and a separator. The electrode plates and the separator are wound to form an electrode assembly, and the separator is located between adjacent turns of electrode plates. The outermost layer of the electrode assembly is the separator. The part of the separator that winds at least one turn from the separator start to the separator end is the inner ring separator, and the part of the separator that winds at least one turn from the separator end to the separator start is the outer ring separator. The thickness of the inner ring separator is less than the thickness of the outer ring separator. The outer ring separator wraps the outermost electrode plate, and the stress on the electrode plate will be transferred to the outer ring separator. The thickness of the outer ring separator increases, the strength and toughness of the outer ring separator increase, and the outer ring separator can absorb more stress, thereby reducing the stress on the outermost electrode plate and reducing the possibility of electrode plate breakage, improving the stability and life of the battery cell.

[0059] The battery cell disclosed in the embodiment of the present application can be but is not limited to being used in power-consuming devices or energy storage devices such as vehicles, ships or aircraft. A power supply system of the power-consuming device or the energy storage device can be composed of the battery cell and the battery dedicated disclosed in the present application. In this way, it is beneficial to reduce the possibility of electrode plate breakage and improve the stability of battery performance and battery life.

[0060] An embodiment of the present application provides a battery cell Figure 1 is a schematic structural diagram of a battery cell provided by an embodiment of the present application. Refer to Figure 1 , the battery cell 100 includes an electrode assembly 200 and a housing 300.

[0061] Figure 2 is Figure 1 an interfacial schematic diagram of the A-A plane of the electrode assembly in Figure 1 and Figure 2, the battery cell 100 includes a pole piece 10 and a separator 20. The pole piece 10 and the separator 20 are wound to form an electrode assembly 200, and the separator 20 is located between adjacent turns of the pole piece 10. Among them, the outermost layer of the electrode assembly 200 is the separator 20. The part where the separator 20 is wound at least one turn from the separator start end to the separator terminal end is the inner ring separator 21, and the part where the separator 20 is wound at least one turn from the separator terminal end to the separator start end is the outer ring separator 22.

[0062] Figure 3 This is a comparison diagram of cross-sectional views of the inner ring separator and the outer ring separator provided by an embodiment of the present application. Refer to Figure 3 , the separator 20 includes a base film 25 and a coating layer 26. The coating layer 26 is located on at least one surface of the base film 25. The thickness D3 of the coating layer 26 of the inner ring separator 21 is less than the thickness D4 of the coating layer 26 of the outer ring separator 22, so that the thickness D1 of the inner ring separator 21 is less than the thickness D2 of the outer ring separator 22.

[0063] The battery cell 100 refers to the smallest unit that makes up the battery. As Figure 1 shown, the housing 300 includes an end cap 301 and a housing 302. The end cap 301 refers to a component that covers the opening of the housing 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 housing 302 to cooperate with the housing 302. Optionally, the end cap 301 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 301 is not easily deformed when subjected to extrusion and collision, enabling the battery cell 100 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 311 can be provided on the end cap 301. The electrode terminal 311 can be used for electrical connection with the electrode assembly 200 to output or input the electrical energy of the battery cell 100. In some embodiments, a pressure relief mechanism 312 for releasing the internal pressure when the internal pressure or temperature of the battery cell 100 reaches a threshold can also be provided on the end cap 301. The material of the end cap 301 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating member can be provided on the inner side of the end cap 301. The insulating member can 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 can be plastic, rubber, etc.

[0064] The housing 302 is a component for cooperating with the end cap 301 to form the internal environment of the battery cell 100. Among them, the formed internal environment can be used to accommodate the electrode assembly 200, the electrolyte, and other components. The housing 302 and the end cap 301 can be independent components. An opening can be provided on the housing 302, and the end cap 301 is covered at the opening to form the internal environment of the battery cell 100. Without limitation, the end cap 301 and the housing 302 can also be integrated. Specifically, the end cap 301 and the housing 302 can first form a common connection surface before other components are put into the housing. When it is necessary to encapsulate the interior of the housing 302, the end cap 301 is then covered on the housing 302. The housing 302 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 302 can be determined according to the specific shape and size of the electrode assembly 200. The material of the housing 302 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0065] The electrode assembly 200 is a component in the battery cell 100 where an electrochemical reaction occurs. The housing 302 can contain one or more electrode assemblies 200. The electrode assembly 200 is formed by winding the electrode plate 10 and the separator 20. The part of the electrode plate 10 with the active material constitutes the main body 203 of the electrode assembly 200, and the part of the electrode plate 10 without the active material constitutes the tab 204. The electrode assembly 200 generally includes two tabs 204 with opposite polarities. The two tabs 204 can be located at one end of the main body 203 together or at both ends of the main body 203 respectively. The tab 204 is connected to the electrode terminal 311 to form an electric current loop, where the tab 204 can be directly connected to the electrode terminal 311, or the tab 204 is connected to the electrode terminal 311 through the adapter plate 313.

[0066] In the embodiment of the present application, the electrode plate 10 and the separator 20 are wound to form the electrode assembly 200, that is, the electrode assembly 200 is a wound electrode assembly. In the embodiment of the present application, the number of winding turns of the electrode assembly 200 can be set according to requirements. Exemplarily, the number of winding turns of the electrode assembly 200 is greater than or equal to 10 and less than or equal to 60. For example, the number of winding turns of the electrode assembly 200 is 50.

[0067] There is a separator 20 between any two adjacent turns of the electrode plate 10, and the electrode plates 10 with opposite polarities do not directly contact each other, reducing the risk of internal short circuit in the battery cell 100.

[0068] The outermost layer of the electrode assembly 200 is the separator 20, that is, the last turn of the electrode assembly 200 is the separator 20. The separator 20 wraps the electrode plate 10. As an insulating layer, the separator 20 can reduce the possibility of the outermost electrode plate 10 directly contacting the external environment and reduce the risk of short circuit.

[0069] In the embodiments of the present application, the side closer to the winding center is the inner side, and the side farther from the winding center is the outer side. The outermost pole piece 10 is a part of the last winding turn of the pole piece 10.

[0070] In the embodiments of the present application, the starting end of the separator refers to the starting end of the winding of the separator 20, and the terminal end of the separator refers to the ending end of the winding of the separator 20.

[0071] It should be noted that Figure 3 Only a simple cross-sectional view of the inner and outer separators is shown.

[0072] The base film 25 provides a basic physical support structure for the separator 20, enabling the separator 20 to maintain a certain shape and size. During battery assembly and use, the base film 25 can withstand the pressure between the electrodes, the stress inside the battery, and the mechanical forces that may be applied externally, etc. The separator 20 will not easily deform, rupture, or be damaged, maintaining the stability of the internal structure of the battery. At the same time, the base film 25 can effectively separate the positive and negative electrodes of the battery, reducing the possibility of direct contact between the positive and negative electrodes and causing a short circuit, and improving the reliability of the battery. The base film 25 can allow ions such as lithium ions required for battery operation to selectively pass between the positive and negative electrodes, providing an ion transport channel for the electrochemical reaction inside the battery. The base film 25 has a certain liquid absorption and retention capacity, can adsorb and retain a certain amount of electrolyte, and make the electrolyte evenly distributed inside the battery.

[0073] The coating layer 26 can optimize the ion transport channel, enabling lithium ions, etc. to conduct 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 good contact with the electrode surface, playing 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 electrode materials or other foreign objects, and improve the stability of the battery. The coating layer 26 can adsorb more electrolyte and evenly retain it inside the separator 20, providing sufficient medium for lithium ion conduction, ensuring smooth ion conduction inside the battery, and also helping to maintain the stability of the electrolyte, reducing the volatilization and drying of the electrolyte. The coating layer 26 can improve the interfacial properties between the separator 20 and the electrolyte, reduce the interfacial resistance between the two, 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 during the charge and discharge process of the battery, and improving the energy efficiency of the battery.

[0074] 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.

[0075] During the charge and discharge cycles of the battery cell 100, the distance between the electrode plates 10 gradually increases, causing the battery cell 100 to expand outward. As the expansion of the battery cell 100 increases, the stress inside the battery cell 100 also gradually increases, and the stress on the battery cell 100 is transmitted from the inside of the battery cell 100 to the surroundings. For the electrode plates 10, the outermost electrode plate 10 is subjected to the greatest stress.

[0076] In the battery cell 100 provided in the embodiment of the present application, the outermost ring of the electrode assembly 200 is the outer ring separator 22. The outer ring separator 22 wraps the outermost electrode plate 10. The stress on the electrode plate 10 is transmitted to the outer ring separator 22, increasing the thickness D4 of the coating layer 26 of the outer ring separator 22 so that the thickness D2 of the outer ring separator 22 increases. The strength and toughness of the outer ring separator 22 increase, and the outer ring separator 22 can absorb more stress, thereby reducing the stress on the outermost electrode plate 10 and reducing the possibility of the electrode plate 10 breaking, improving the stability and lifespan of the battery cell 100.

[0077] Among them, toughness represents the ability of a material to absorb energy during plastic deformation and fracture. The better the toughness, the smaller the possibility of brittle fracture. The toughness of the outer ring separator 22 increases, the stress absorption ability of the outer ring separator 22 increases, the strength of the outer ring separator 22 increases, and the damage resistance ability of the outer ring separator 22 increases.

[0078] In the embodiment of the present application, the outer ring separator 22 covers at least one full turn of the electrode plate 10, and the outermost electrode plate 10 can transmit stress to the outer ring separator 22.

[0079] According to some embodiments of the present application, see Figure 2 , the electrode plate 10 includes a first electrode plate 11 and a second electrode plate 12, the separator 20 includes a first separator 23 and a second separator 24. The first electrode plate 11, the first separator 23, the second electrode plate 12, and the second separator 24 are stacked and wound in sequence to form the electrode assembly 200. The outermost ring of the electrode assembly 200 is the first separator 23, and the outermost ring of the first electrode plate 11 wraps the outermost ring of the second electrode plate 12. The first separator 23 includes an inner ring separator 21 and an outer ring separator 22.

[0080] In order to clearly show the Figure 2 electrode plate 10 and the separator 20 in Figure 2 , the first electrode plate 11 is shown in red, the second electrode plate 12 is shown in green, the first separator 23 is shown in blue, and the second separator 24 is shown in black. Among them, the lines of the inner ring separator 21 are thinner than those of the outer ring separator 22.

[0081] In the embodiment of the present application, the polarities of the first electrode plate 11 and the second electrode plate 12 are opposite.

[0082] In the initial stage of winding, after the first separator 23 winds for a certain length before the first pole piece 11, the first pole piece 11 starts to wind, so that the first pole piece 11 at the winding center can be separated by the first separator 23.

[0083] In the termination stage of winding, the first pole piece 11 continues to wind for at least one more turn after the second pole piece 12 finishes winding, so that the outermost layer of the first pole piece 11 wraps the outermost layer of the second pole piece 12. The second separator 24 continues to wind for at least one more turn after the first pole piece 11 finishes winding, so that the second separator 24 can separate the first pole piece 11 and the second pole piece 12. The first separator 23 continues to wind for at least one more turn after the second separator 24 finishes winding, so that the outermost layer of the electrode assembly 200 is the first separator 23.

[0084] In the embodiment of the present application, the outer separator 22 of the first separator 23 is the outermost layer of the electrode assembly 200.

[0085] In the embodiment of the present application, two layers of isolation films are provided, namely the first separator 23 and the second separator 24. During the winding process, any adjacent two turns of the first pole piece 11 and the second pole piece 12 can be separated by one of the first separator 23 and the second separator 24, improving the stability of the battery cell 100. Since the first separator 23 is located in the outermost layer, both the stress of the first pole piece 11 and the stress of the second pole piece 12 are transmitted to the first separator 23. By providing the outer separator 22 on the first separator 23, the outer separator 22 of the first separator 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 lifespan of the battery cell 100.

[0086] According to some embodiments of the present application, the second separator 24 includes an inner separator 21 and an outer separator 22.

[0087] Since the first pole piece 11, the first separator 23, the second pole piece 12, and the second separator 24 are stacked and wound in sequence to form the electrode assembly 200, during the winding process, the first separator 23 wraps the first pole piece 11, and the second separator 24 wraps the second pole piece 12.

[0088] In the electrode assembly 200, there is stress in both the first pole piece 11 and the second pole piece 12. The first pole piece 11 transmits stress to the first separator 23, and the second pole piece 12 transmits stress to the second separator 24. By providing the outer separator 22 on both the first separator 23 and the second separator 24, the outer separator 22 of the first separator 23 and the outer separator 22 of the second separator 24 can both 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 the first pole piece 11 and the second pole piece 12 breaking, and improve the stability and lifespan of the battery cell 100.

[0089] In the embodiments of the present application, the first electrode tab 11 transmits stress to the first separator 23, which does not mean that the first electrode tab 11 only transmits stress to the first separator 23. The first electrode tab 11 may transmit part of the stress to the first separator 23 or part of the stress to the second separator 24. Similarly, the second electrode tab 12 may transmit part of the stress to the second separator 24 or part of the stress to the first separator 23.

[0090] According to some embodiments of the present application, a part of the second electrode tab 12 that winds one turn from the second electrode tab terminal to the second electrode tab start is the outer ring second electrode tab 121, and one side of the outer ring separator 22 close to the start of the isolation film is opposite to one side of the outer ring second electrode tab 121 close to the second electrode tab start.

[0091] In the embodiments of the present application, the second electrode tab start refers to the starting end of the winding of the second electrode tab 12, and the second electrode tab terminal refers to the terminating end of the winding of the second electrode tab 12.

[0092] Since the isolation film 20 needs to completely cover the electrode tab 10, the isolation film 20 will continue to wind after the winding of the electrode tab 10 is completed. It can be understood that the isolation film terminal will extend beyond the second electrode tab terminal. At the same time, one side of the outer ring separator 22 close to the start of the isolation film is opposite to one side of the outer ring second electrode tab 121 close to the second electrode tab start. Then, the number of turns of the outer ring separator 22 is greater than 1.

[0093] In the embodiments of the present application, one side of the outer ring separator 22 close to the start of the isolation film is opposite to one side of the outer ring second electrode tab 121 close to the second electrode tab start, which can enable the outer ring separator 22 to cover the outermost ring of the electrode tab 10. The outer ring separator 22 can absorb the stress of the outermost ring of the electrode tab 10 and reduce the stress of the electrode tab 10.

[0094] According to some embodiments of the present application, the inner ring separator 21 and the outer ring separator 22 on the same isolation film 20 are adjacent to each other.

[0095] The inner ring separator 21 and the outer ring separator 22 on the same isolation film 20 are adjacent to each other, which can be understood as the coincidence of the opposite sides of the inner ring separator 21 and the outer ring separator 22. In the embodiments of the present application, for the same isolation film 20, a part of the isolation film is the inner ring separator 21, and another part of the isolation film is the outer ring separator 22.

[0096] In the embodiments of the present application, the inner ring separator 21 of the first separator 23 is adjacent to the outer ring separator 22 of the first separator 23; the inner ring separator 21 of the second separator 24 is adjacent to the outer ring separator 22 of the second separator 24.

[0097] In the embodiments of the present application, the part of the isolation film 20 excluding the outer ring separator 22 is the inner ring separator 21. The isolation film 20 only includes two different thicknesses, and the process of manufacturing the isolation film 20 is simpler, which simplifies the manufacturing process.

[0098] In an embodiment of the present application, the part of the second pole piece 12 that is wound at least one turn from the start end of the second pole piece to the end of the second pole piece is the inner-ring second pole piece; the part of the first pole piece 11 that is wound at least one turn from the end of the first pole piece to the start of the first pole piece is the outer-ring first pole piece; the part of the first pole piece 11 that is wound at least one turn from the start of the first pole piece to the end of the first pole piece is the inner-ring first pole piece. One side of the outer-ring first pole piece close to the start of the first pole piece is opposite to one side of the outer-ring second pole piece 121 close to the start of the second pole piece.

[0099] Exemplarily, referring to Figure 2 , in the first pole piece 11, the part from B1 to B2 is the inner-ring first pole piece, and the part from B2 to B3 is the outer-ring first pole piece; in the second pole piece 12, the part from C1 to C2 is the inner-ring second pole piece, and the part from C2 to C3 is the outer-ring second pole piece; in the first separator 23, the part from E1 to E2 is the inner-ring separator 21 of the first separator 23, and the part from E2 to E3 is the outer-ring separator 22 of the first separator 23; in the second separator 24, the part from F1 to F2 is the inner-ring separator 21 of the second separator 24, and the part from F2 to F3 is the outer-ring separator 22 of the second separator 24. That is, B1 is the winding start end of the first pole piece 11, B3 is the winding end of the first pole piece 11; C1 is the winding start end of the second pole piece 12, C3 is the winding end of the second pole piece 12; E1 is the winding start end of the first separator 23, E3 is the winding end of the first separator 23; F1 is the winding start end of the second separator 24, F3 is the winding end of the second separator 24.

[0100] In Figure 2 , the number of winding turns of the first pole piece 11, the second pole piece 12, the first separator 23 and the second separator 24 are only examples.

[0101] 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.

[0102] In an embodiment of the present application, in the termination stage of winding, the anode piece will continue to wind at least one turn after the cathode piece finishes winding, so that the cathode piece can be wrapped by the anode piece.

[0103] In an embodiment of the present application, the outermost layer of the first pole piece 11 wraps the outermost layer 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, and the lithium ions generated by the cathode can be more fully and orderly embedded into the vacant positions of the anode, which helps to improve the overall capacity and charge-discharge stability of the battery cell and improve the reliability of the battery cell.

[0104] According to some embodiments of the present application, the ratio of the thickness D1 of the inner diaphragm 21 to the thickness D2 of the outer diaphragm 22 is greater than or equal to 0.2 and less than or equal to 0.95.

[0105] According to some embodiments of the present application, the ratio of the thickness D1 of the inner diaphragm 21 to the thickness D2 of the outer diaphragm 22 is greater than or equal to 0.3 and less than or equal to 0.85.

[0106] According to some embodiments of the present application, the ratio of the thickness D1 of the inner diaphragm 21 to the thickness D2 of the outer diaphragm 22 is greater than or equal to 0.4 and less than or equal to 0.75.

[0107] Exemplarily, the ratio of the thickness D1 of the inner diaphragm 21 to the thickness D2 of the outer diaphragm 22 is equal to 0.5; or the ratio of the thickness D1 of the inner diaphragm 21 to the thickness D2 of the outer diaphragm 22 is equal to 0.6.

[0108] If the ratio of the thickness D1 of the inner diaphragm 21 to the thickness D2 of the outer diaphragm 22 is too small, then there are two cases: the thickness D1 of the inner diaphragm 21 is small, or the thickness D2 of the outer diaphragm 22 is large. If the thickness D1 of the inner diaphragm 21 is small, then the mechanical strength of the inner diaphragm 21 is reduced, and the physical barrier effect of the inner diaphragm 21 will be weakened. During the charge and discharge process of the battery, micro-short circuit or even direct short circuit between the positive and negative electrodes is likely to occur. If the thickness D2 of the outer diaphragm 22 is large, then the outer diaphragm 22 will generate a certain resistance to the transmission of lithium ions, etc., resulting in a slowdown of the charge and discharge process of the battery, a reduction in the charge and discharge efficiency of the battery, and at the same time, it will also increase the volume of the battery cell and reduce the energy density of the battery cell.

[0109] If the ratio of the thickness D1 of the inner diaphragm 21 to the thickness D2 of the outer diaphragm 22 is too large, then there are two cases: the thickness D1 of the inner diaphragm 21 is large, or the thickness D2 of the outer diaphragm 22 is small. If the thickness D1 of the inner diaphragm 21 is large, then the thickness D2 of the outer diaphragm 22 will be even larger, which will reduce the energy density of the battery cell. If the thickness D2 of the outer diaphragm 22 is small, then the thickness D2 of the inner diaphragm 21 will be even smaller, and micro-short circuit or even direct short circuit between the positive and negative electrodes is likely to occur.

[0110] Embodiments of the present application limit the ratio of the thickness D1 of the inner diaphragm 21 to the thickness D2 of the outer diaphragm 22 within the above range, which can improve the safety of the battery and at the same time reduce the impact on the energy density of the battery cell.

[0111] According to some embodiments of the present application, referring to Figure 3 ..., for the inner diaphragm 21, the coating layer 26 is located on one side surface of the base film 25; for the outer diaphragm 22, the coating layer 26 is located on both side surfaces of the base film 25.

[0112] In an embodiment of the present application, the thicknesses of the coating layers 26 on the same side surface of the base film 25 may be equal or unequal.

[0113] In an embodiment of the present application, two coating layers 26 are provided on the outer ring separator 22, and it is not necessary to modify the manufacturing process of the coating layer 26 of the inner ring separator 21, which simplifies the manufacturing process.

[0114] 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 separator 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 separator 22, the thickness D4 of the coating layer 26 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.

[0115] In an embodiment of the present application, the thickness of the coating layer 26 may satisfy any one of the above conditions or satisfy both of the above conditions.

[0116] In an embodiment of the present application, the thickness of the coating layer 26 refers to the thickness of one coating layer 26.

[0117] Exemplarily, for the inner ring separator 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 separator 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.

[0118] In an embodiment of the present application, by respectively defining the thicknesses of the coating layers 26 in the inner ring separator 21 and the outer ring separator 22, the thicknesses of the inner ring separator 21 and the outer ring separator 22 can be adjusted by respectively adjusting the thicknesses of the coating layers 26.

[0119] According to some embodiments of the present application, the material of the base film 25 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyolefin materials, and polyolefin modified materials.

[0120] The above materials have good liquid absorption and retention capabilities, can adsorb and retain a certain amount of electrolyte, make the electrolyte evenly distributed inside the battery, provide a good medium environment for ion conduction, help improve the efficiency and uniformity of ion transport inside the battery, and thus enhance the overall performance and stability of the battery.

[0121] According to some embodiments of the present application, the coating layer 26 includes a ceramic coating.

[0122] The ceramic coating enhances the high-temperature resistance of the separator 20, improves the thermal stability of the separator 20, improves the thermal shrinkage phenomenon of the separator 20, and can also enhance the puncture resistance of the separator 20, improving the reliability of the battery.

[0123] According to some embodiments of the present application, the material of the ceramic coating includes at least one of alumina, boehmite, silica, zirconia, and titanium oxide.

[0124] The above materials are relatively common ceramic coating materials, which are easy to obtain and reduce the manufacturing cost.

[0125] 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%.

[0126] 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%.

[0127] Defining the porosity of the coating layer 26 to be greater than or equal to 40%, the coating layer 26 can provide a smooth transmission channel for lithium ions, enabling lithium ions to move between the electrodes on both sides of the separator through these pores, improving the charge and discharge performance and efficiency of the battery. Defining the porosity of the coating layer 26 to be less than or equal to 80% will not reduce the strength and isolation function of the separator 20 due to excessive porosity, while reducing the impact on the electrolyte adsorption of the separator 20.

[0128] According to some embodiments of the present application, referring to Figure 3 , the separator 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.

[0129] In the embodiments of the present application, for the inner ring separator 21, one adhesive layer 27 is in contact with the base film 25, and the other adhesive layer 27 is in contact with the coating layer 26. For the outer ring separator 22, both adhesive layers 27 are in contact with the coating layer 26.

[0130] In the embodiments of the present application, the adhesive layer 27 can bond the electrode plate 10, improving the firmness of the connection between the separator 20 and the electrode plate 10.

[0131] 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 resin.

[0132] The above materials have good adhesion performance, which can improve the adhesion performance of the adhesive layer 27. At the same time, the above materials are easy to obtain, reducing the cost of manufacturing the separator 20.

[0133] According to some embodiments of the present application, the thickness D5 of the adhesive layer 27 is greater than or equal to 1 μm and less than or equal to 10 μm.

[0134] 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.

[0135] In an embodiment of the present application, it is defined that the thickness D5 of the adhesive layer 27 is greater than or equal to 1 μm, so that the separator 20 has a sufficient adhesive layer 27 for bonding the electrode tab 10; it is defined that the thickness D5 of the adhesive layer 27 is less than or equal to 10 μm, so as to reduce the influence on the lithium ion transport due to the too large thickness of the adhesive layer 27.

[0136] According to some embodiments of the present application, the adhesive force of the adhesive layer 27 is greater than or equal to 5 N (Newton) and less than or equal to 25 N.

[0137] Exemplarily, the adhesive force of the adhesive layer 27 is equal to 8 N; or the adhesive force of the adhesive layer 27 is equal to 10 N; or the adhesive force of the adhesive layer 27 is equal to 12 N; or the adhesive force of the adhesive layer 27 is equal to 15 N; or the adhesive force of the adhesive layer 27 is equal to 20 N; or the adhesive force of the adhesive layer 27 is equal to 22 N.

[0138] In an embodiment of the present application, it is defined that the adhesive force of the adhesive layer 27 is greater than or equal to 5 N, so that the adhesive layer 27 has sufficient adhesive force to bond the electrode tab 10; if the adhesive force of the adhesive layer 27 is too strong, the contact between the separator 20 and the electrode tab 10 may be too tight, resulting in the hindrance of lithium ion transport at the interface between the separator 20 and the electrode tab 10. It is defined that the adhesive force of the adhesive layer 27 is less than or equal to 25 N to reduce the influence of the adhesive layer 27 on lithium ion transport.

[0139] According to some embodiments of the present application, Figure 4 is a cross-sectional view of another electrode assembly provided by an embodiment of the present application. Refer to Figure 4 , the electrode assembly 200 has a bending region 201 and a flat region 202. The electrode tab 10 includes a first sub-electrode tab 13 and a second sub-electrode tab 14. The first sub-electrode tab 13 is located in the bending region 201, and the second sub-electrode tab 14 is at least located in the flat region 202.

[0140] Figure 5 is a comparison diagram of cross-sectional views of a first sub-electrode tab and a second sub-electrode tab provided by an embodiment of the present application. Refer to Figure 5 , the thickness D6 of the first sub-electrode tab 13 is less than the thickness D7 of the second sub-electrode tab 14.

[0141] In an embodiment of the present application, for the electrode tabs 10 with the same polarity, along the winding direction of the electrode assembly 200, the first sub-electrode tab 13 and the second sub-electrode tab 14 are adjacent.

[0142] In an embodiment of the present application, the wound electrode assembly 200 may include two bending regions 201 and a straight region 202. The two bending regions 201 are respectively located on opposite sides of the straight region 202, and both bending 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 implementation manners, the electrode assembly 200 may include other numbers of bending regions 201 and straight regions 202.

[0143] It should be noted that the straight region 202 only has a smaller curvature relative to the bending region 201, which does not mean that the straight region 202 is completely straight.

[0144] In an embodiment of the present application, the first sub-electrode tab 13 is located in the bending region 201. The second sub-electrode tab 14 may be located in the straight region 202 or in the bending region 201. The electrode tabs 10 located in the bending region 201 are not necessarily all the first sub-electrode tabs 13.

[0145] During the charge and discharge cycle of the battery cell 100, the distance between the electrode tabs 10 will gradually increase, causing the battery cell 100 to expand outward. The electrode tabs 10 will also be squeezed. The stress on the electrode tabs 10 located in the bending region 201 is greater than the stress on the electrode tabs 10 located in the straight region 202. During the long-term use of the battery cell 100, the stress on the electrode tabs 10 located in the bending region 201 will gradually accumulate, which may cause the electrode tabs 10 to rupture and affect the stability of the battery cell 100.

[0146] In an embodiment of the present application, a part of the electrode tabs 10 located in the bending region 201 is set as the first sub-electrode tab 13 with a smaller thickness. The distance between the first sub-electrode tab 13 and its adjacent electrode tabs is larger, so that the electrode tabs 10 located in the bending region 201 have more expansion space, reduce the stress on the electrode tabs 10, reduce the possibility of the electrode tabs 10 breaking, and improve the stability and lifespan of the battery cell 100.

[0147] In an embodiment of the present application, assume that a certain section of the electrode tab 10 enters the bending region 201 from point G and exits the bending region 201 from point H, and the part of the electrode tab 10 from point G to point H is entirely located in the bending region 201. Then, the entire part of the electrode tab 10 from point G to point H is the first sub-electrode tab 13; or a part of the electrode tab 10 from point G to point H is the first sub-electrode tab 13 and the other part is the second sub-electrode tab 14.

[0148] In an embodiment of the present application, a certain section of the pole piece 10 enters the bending region 201 from point G and exits the bending region 201 from point H. If the pole piece 10 is unfolded, the direction from point G to point H is the length direction of the pole piece 10. The width of the first sub-pole piece 13 between point G and point H can be equal to the width of the pole piece 10, or the width of the first sub-pole piece 13 between point G and point H is less than the width of the pole piece 10.

[0149] 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.

[0150] In an embodiment of the present application, during the expansion of the battery cell 100, the stress on the pole piece 10 located on the outer circle is greater than the stress on the pole piece 10 located on the inner circle, and the stress on the pole piece 10 located in the bending region 201 is greater than the stress on the pole piece 10 located in the straight region 202. Generally speaking, the stress on the outermost pole piece 10 in the bending region 201 is greater than the stress on other pole pieces 10, and the outermost pole piece 10 in the bending region 201 is more likely to break.

[0151] Since the stress on the outermost pole piece 10 in the bending region 201 is greater than the stress on other pole pieces 10, setting the outermost pole piece 10 in the bending region 201 as the first sub-pole piece 13 can greatly reduce the stress on the outermost pole piece 10 in the bending region 201 and reduce the possibility of the pole piece 10 breaking.

[0152] According to some embodiments of the present application, Figure 6 is a cross-sectional view of another electrode assembly provided by the embodiment of the present application. Refer to Figure 6 , 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 in the bending region 201 has n turns. 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. Among them, 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.

[0153] In an embodiment of the present application, for the pole pieces 10 with the same polarity, the fact that the first sub-pole piece 13 in the bending region 201 has n turns means that the first sub-pole pieces 13 with the same polarity and located in the same bending region 201 have n turns.

[0154] In an embodiment of the present application, the battery cell 100 includes pole pieces 10 of two polarities, and at least one polarity of the pole pieces 10 satisfies the above conditions.

[0155] In an embodiment of the present application, the first sub - pole piece 13 that is less than a full turn in the bending region 201 is also counted as one turn.

[0156] Exemplarily, n can be greater than or equal to 3 and less than or equal to 30; m can be greater than or equal to 5 and less than or equal to 10.

[0157] 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 bending region 201, the number of second sub - pole pieces 14 between the (n - 1)-th turn of the first sub - pole pieces 13 and the n - th turn of the first sub - pole pieces 13 is less than the number of second sub - pole pieces 14 between any other two adjacent turns of the first sub - pole pieces 13.

[0158] Exemplarily, k can 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 turn of the first sub - pole pieces 13 and the n - th turn of the first sub - pole pieces 13.

[0159] Since the thickness of the first sub - pole piece 13 decreases, the strength of the first sub - pole piece 13 will decrease. In an embodiment of the present application, the first sub - pole pieces 13 are arranged at intervals in the bending region 201 to reduce the influence on the strength of the bending region caused by the reduction of the strength of the first sub - pole piece 13.

[0160] 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 part of the first pole piece 11 located in the outermost circle of the bending region 201 is the first sub - pole piece 13; the part of the second pole piece 12 located in the outermost circle of the bending region 201 is the first sub - pole piece 13.

[0161] That is, for any pole piece 10 of a certain polarity, the part located in the outermost circle of the bending region 201 is the first sub - pole piece 13.

[0162] In an embodiment of the present application, setting the outermost - circle parts of both the first pole piece 11 and the second pole piece 12 as the first sub - pole piece 13 can reduce the possibility of the first pole piece 11 and the second pole piece 12 breaking.

[0163] Exemplarily, assuming that there are 42 turns of the first pole piece 11 in the same bending region 201, then the first pole piece 11 at the 5th turn, 10th turn, 15th turn, 20th turn, 25th turn, 30th turn, 35th turn, 40th turn, and 42nd turn in the bending region 201 can be the first sub - pole piece 13.

[0164] According to some embodiments of the present application, in the case where the electrode sheet 10 includes a first electrode sheet 11 and a second electrode sheet 12, the first electrode sheet 11 includes a first sub-electrode sheet 13 and a second sub-electrode sheet 14, the second electrode sheet 12 includes a first sub-electrode sheet 13 and a second sub-electrode sheet 14, and the number of turns of the first sub-electrode sheet 13 in the first electrode sheet 11 is equal to the number of turns of the first sub-electrode sheet 13 in the second electrode sheet 12.

[0165] It can be understood that the portion with reduced thickness in the first electrode sheet 11 corresponds to the portion with reduced thickness in the second electrode sheet 12.

[0166] The electrode sheet 10 is used to store and transport lithium ions. The thickness of the first sub-electrode sheet 13 is less than that of the second sub-electrode sheet 14, and the ability of the first sub-electrode sheet 13 to store and transport lithium ions is relatively weak. During the charge and discharge process of the battery cell 100, lithium ions move in the first electrode sheet 11 and the second electrode sheet 12. If the ability of a certain part of the first electrode sheet 11 to store and transport lithium ions weakens, even if the second electrode sheet 12 opposite to it has a strong ability to store and transport lithium ions, the ability to transport lithium ions between this part of the first electrode sheet 11 and the second electrode sheet 12 will also be weak, that is, the capacity contributed by this part of the first electrode sheet 11 and the second electrode sheet 12 is small.

[0167] In the embodiments of the present application, the portion with reduced thickness in the first electrode sheet 11 corresponds to the portion with reduced thickness in the second electrode sheet 12. This part of the first electrode sheet 11 and the second electrode sheet 12 can provide expansion space and can also reduce the impact on the energy density of the battery cell 100.

[0168] According to some embodiments of the present application, refer to Figure 5 , the electrode sheet 10 includes a current collector 15 and an active material layer 16. The active material layer 16 is located on at least one surface of the current collector 15. The first sub-electrode sheet 13 and the second sub-electrode sheet 14 satisfy one of the following conditions.

[0169] Refer to Figure 5 , both the first sub-electrode sheet 13 and the second sub-electrode sheet 14 include a current collector 15 and an active material layer 16, and the thickness D8 of the active material layer 16 of the first sub-electrode sheet 13 is less than the thickness D9 of the active material layer 16 of the second sub-electrode sheet 14.

[0170] Figure 7 It is a developed schematic diagram of an electrode sheet provided by an embodiment of the present application. Refer to 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.

[0171] 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 basis for the active material, enabling the active material to remain in a specific position and form a complete electrode structure.

[0172] The active material in the active material layer 16 can reversibly intercalate and deintercalate 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 undergoes redox reactions. During the electrochemical reaction process, electrons can be conducted between the active material particles and between the active material and the current collector 15, enabling the smooth electron transfer inside the battery, thereby ensuring the normal charge and discharge of the battery.

[0173] In some embodiments of the present application, the first sub-electrode 13 may not be provided with the active material layer 16. For example, the active material layer 16 can be coated on the second sub-electrode 14 by intermittent coating; or the active material layer 16 can be coated on both the first sub-electrode 13 and the second sub-electrode 14, and then the active material layer on the first sub-electrode 13 can be cleaned, and the cleaning method can be laser cleaning.

[0174] In some other embodiments of the present application, the thickness of the active material layer 16 on the first sub-electrode 13 can be reduced.

[0175] When the thickness of the active material layer 16 on the first sub-electrode 13 is reduced, the active material layer 16 can be provided on one side surface of the current collector 15, or the active material layer 16 can be provided on both side surfaces of the current collector 15.

[0176] 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.

[0177] The embodiments of the present application provide a battery device, and the battery device includes the battery cell of any one of the above.

[0178] Figure 8Schematic exploded view of a battery device provided by some embodiments of the present application. The battery device 400 includes a box body 500 and battery cells 100, and the battery cells 100 are accommodated in the box body 500. Among them, the box body 500 is used to provide an accommodation space for the battery cells 100, and the box body 500 can adopt various structures. In some embodiments, the box body 500 may include a first part 501 and a second part 502. The first part 501 and the second part 502 cover each other, and the first part 501 and the second part 502 jointly define an accommodation space for accommodating the battery cells 100. The second part 502 may be a hollow structure with one end open, and the first part 501 may be a plate-like structure. 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 an accommodation space; the first part 501 and the second part 502 may also both 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 various shapes, such as a cylinder, a cuboid, etc.

[0179] In the battery device 400, there may be multiple battery cells 100, and the multiple battery cells 100 can be connected in series, in parallel, or in a mixed connection. A mixed connection means that there are both series and parallel connections among the multiple battery cells 100. The multiple battery cells 100 can be directly connected in series, in parallel, or in a mixed connection together, and then the whole formed by the multiple battery cells 100 is accommodated in the box body 500; of course, the battery device 400 can also be that multiple battery cells 100 are first connected in series, in parallel, or in a mixed connection to form a battery module form, and then multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole and are accommodated in the box body 500. The battery device 400 may further include other structures. For example, the battery device 400 may further include a busbar component for realizing electrical connection among the multiple battery cells 100.

[0180] Among them, each battery cell 100 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto.

[0181] In the battery device 400 provided by the embodiments of the present application, the possibility of the pole piece 10 breaking is reduced, and the stability and lifespan of the battery device 400 are improved.

[0182] The embodiments of the present application provide an electrical device. The electrical device includes the above-mentioned battery device 400, and the battery device 400 is used to provide electrical energy.

[0183] An embodiment of the present application provides an electrical device using a battery device as a power source. The electrical device can be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, etc. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric aircraft toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle, a spaceship, etc.

[0184] For the convenience of description in the following embodiments, a vehicle 1000, which is an electrical device according to an embodiment of the present application, is taken as an example for illustration.

[0185] Figure 9 It is a schematic structural diagram of a vehicle provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery device 400 is disposed inside the vehicle 1000. The battery device 400 can be disposed at the bottom, the head or the tail of the vehicle 1000. The battery device 400 can be used for power supply of the vehicle 1000. For example, the battery device 400 can be used as an operating power source of the vehicle 1000. The vehicle 1000 may further include a controller 600 and a motor 700. The controller 600 is used to control the battery device 400 to supply power to the motor 700. For example, it is used for the working power requirements during the start, navigation and driving of the vehicle 1000.

[0186] In some embodiments of the present application, the battery device 400 can not only be used as an operating power source of the vehicle 1000, but also be used as a driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0187] The electrical device provided by the embodiment of the present application has higher lifespan and stability.

[0188] An embodiment of the present application provides an energy storage device. The energy storage device includes the battery device in the above embodiment, and the battery device is used for storing electric energy.

[0189] The energy storage device can 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, etc.

[0190] The energy storage device provided by the embodiment of the present application has higher lifespan and stability.

[0191] Embodiments of the present application provide a battery cell. The battery cell 100 includes a pole piece 10 and a separator 20. The pole piece 10 and the separator 20 are wound to form an electrode assembly 200, and the separator 20 is located between adjacent turns of the pole piece 10. Among them, the outermost layer of the electrode assembly 200 is the separator 20. The part where the separator 20 winds at least one turn from the separator start end to the separator end is the inner ring separator 21, and the part where the separator 20 winds at least one turn from the separator end to the separator start end is the outer ring separator 22. The ratio of the thickness D1 of the inner ring separator 21 to the thickness D2 of the outer ring separator 22 is greater than or equal to 0.4 and less than or equal to 0.75.

[0192] The pole piece 10 includes a first pole piece 11 and a second pole piece 12. The separator 20 includes a first separator 23 and a second separator 24. The first pole piece 11, the first separator 23, the second pole piece 12, and the second separator 24 are stacked and wound in sequence to form the electrode assembly 200. The outermost layer of the electrode assembly 200 is the first separator 23, and the outermost layer of the first pole piece 11 wraps the outermost layer of the second pole piece 12. The first separator 23 includes an inner ring separator 21 and an outer ring separator 22. The second separator 24 includes an inner ring separator 21 and an outer ring separator 22. The first pole piece 11 is an anode piece, and the second pole piece 12 is a cathode piece. The inner ring separator 21 and the outer ring separator 22 on the same separator 20 are adjacent to each other.

[0193] The part where the second pole piece 12 winds one turn from the second pole piece end to the second pole piece start end is the outer ring second pole piece 121. The side of the outer ring separator 22 close to the separator start end is opposite to the side of the outer ring second pole piece 121 close to the second pole piece start end.

[0194] The separator 20 includes a base film 25 and a coating layer 26. The coating layer 26 is located on at least one surface of the base film 25. The thickness D3 of the coating layer 26 of the inner ring separator 21 is less than the thickness D4 of the coating layer 26 of the outer ring separator 22. For the inner ring separator 21, the coating layer 26 is located on one surface of the base film 25; for the outer ring separator 22, the coating layer 26 is located on both surfaces of the base film 25. For the inner ring separator 21, the thickness of the coating layer 26 is greater than or equal to 1 μm and less than or equal to 5 μm; for the outer ring separator 22, the thickness of the coating layer 26 located on one surface of the base film 25 is greater than or equal to 4 μm and less than or equal to 1 μm.

[0195] 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 alumina, boehmite, silica, zirconia, 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 separator 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. The material of the adhesive layer 27 includes at least one of polyvinylidene fluoride homopolymer, polyvinylidene fluoride copolymer, polyvinyl chloride, polyethylene oxide, and polymethacrylic resin. The thickness D5 of the adhesive layer 27 is greater than or equal to 1 μm and less than or equal to 10 μm. The adhesive force of the adhesive layer 27 is greater than or equal to 5 N and less than or equal to 25 N.

[0196] The electrode assembly 200 has a bending region 201 and a flat region 202. The electrode sheet 10 includes a first sub-electrode sheet 13 and a second sub-electrode sheet 14. The first sub-electrode sheet 13 is located in the bending region 201, and the second sub-electrode sheet 14 is located in the flat region 202 and the bending region 201. The thickness D5 of the first sub-electrode sheet 13 is less than the thickness D6 of the second sub-electrode sheet 14. The outermost part of the first electrode sheet 11 located in the bending region 201 is the first sub-electrode sheet 13; the outermost part of the second electrode sheet 12 located in the bending region 201 is the first sub-electrode sheet 13.

[0197] For the electrode sheets 10 with the same polarity, the first sub-electrode sheet 13 located in the bending region 201 has n turns. There are m turns of the second sub-electrode sheet 14 between any two adjacent turns of the first sub-electrode sheet 13 from the first turn of the first sub-electrode sheet 13 to the (n - 1)th turn of the first sub-electrode sheet 13, and there are k turns of the second sub-electrode sheet 14 between the (n - 1)th turn of the first sub-electrode sheet 13 and the nth turn of the first sub-electrode sheet 13. Among them, 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.

[0198] The first electrode sheet 11 includes a first sub-electrode sheet 13 and a second sub-electrode sheet 14. The second electrode sheet 12 includes a first sub-electrode sheet 13 and a second sub-electrode sheet 14. The number of turns of the first sub-electrode sheet 13 in the first electrode sheet 11 is equal to the number of turns of the first sub-electrode sheet 13 in the second electrode sheet 12.

[0199] The electrode sheet 10 includes a current collector 15 and an active material layer 16. 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.

[0200] 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 foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present application, and they should all be covered within the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, The battery cell (100) includes a pole piece (10) and a separator (20). The pole piece (10) and the separator (20) are wound to form an electrode assembly (200), and the separator (20) is located between adjacent turns of the pole piece (10). The outermost layer of the electrode assembly (200) is the separator (20). The part of the separator (20) that winds at least one turn from the separator start end to the separator terminal end is the inner ring separator (21), and the part of the separator (20) that winds at least one turn from the separator terminal end to the separator start end is the outer ring separator (22). Wherein, the separator (20) includes a base film (25) and a coating layer (26). The coating layer (26) is located on at least one surface of the base film (25). The thickness of the coating layer (26) of the inner ring separator (21) is less than the thickness of the coating layer (26) of the outer ring separator (22).

2. The battery cell according to claim 1, characterized in that, The pole piece (10) includes a first pole piece (11) and a second pole piece (12). The separator (20) includes a first separator (23) and a second separator (24). The first pole piece (11), the first separator (23), the second pole piece (12), and the second separator (24) are stacked and wound in sequence to form the electrode assembly (200). The outermost layer of the electrode assembly (200) is the first separator (23), and the outermost layer of the first pole piece (11) wraps the outermost layer of the second pole piece (12). The first separator (23) includes the inner ring separator (21) and the outer ring separator (22).

3. The battery cell according to claim 2, wherein The second separator (24) includes the inner ring separator (21) and the outer ring separator (22).

4. The battery cell according to claim 2, wherein The part of the second pole piece (12) that winds one turn from the second pole piece terminal end to the second pole piece start end is the outer ring second pole piece (121). The side of the outer ring separator (22) close to the separator start end is opposite to the side of the outer ring second pole piece (121) close to the second pole piece start end.

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

6. The battery cell according to claim 2, wherein, 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 separator (21) to the thickness of the outer ring separator (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 separator (21) to the thickness of the outer ring separator (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, wherein, The ratio of the thickness of the inner ring separator (21) to the thickness of the outer ring separator (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 separator (21), the coating layer (26) is located on one surface of the base film (25). For the outer ring separator (22), the coating layer (26) is located on both surfaces of the base film (25).

11. The battery cell according to claim 10, wherein The thickness of the coating layer (26) satisfies at least one of the following conditions: For the inner ring diaphragm (21), the thickness of the coating layer (26) is greater than or equal to 1 μm and less than or equal to 5 μm; For the outer ring diaphragm (22), the thickness of the coating layer (26) on one surface of the base film (25) is 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 materials, and polyolefin modified materials.

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 alumina, boehmite, silica, zirconia, 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 separator membrane (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).

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 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, wherein, The adhesive force of the adhesive layer (27) is greater than or equal to 5 N and less than or equal to 25 N.

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

21. The battery cell according to claim 20, wherein, The outermost electrode sheet (10) in the bending region (201) is the first sub-electrode sheet (13).

22. The battery cell according to claim 21, characterized in that, The second sub-electrode sheet (14) is also located in the bending region (201). For the electrode sheets (10) with the same polarity, the first sub-electrode sheet (13) in the bending region (201) has n turns. There are m turns of the second sub-electrode sheet (14) between any two adjacent turns of the first sub-electrode sheet (13) from the first turn of the first sub-electrode sheet (13) to the (n - 1)-th turn of the first sub-electrode sheet (13), and there are k turns of the second sub-electrode sheet (14) between the (n - 1)-th turn of the first sub-electrode sheet (13) and the n-th turn of the first sub-electrode sheet (13), where 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 electrode sheet (10) includes a first electrode sheet (11) and a second electrode sheet (12), the outermost part of the first electrode sheet (11) in the bending region (201) is the first sub-electrode sheet (13); The outermost part of the second electrode sheet (12) in the bending region (201) is the first sub-electrode sheet (13).

24. The battery cell according to claim 20, wherein, In the case where the electrode sheet (10) includes a first electrode sheet (11) and a second electrode sheet (12), the first electrode sheet (11) includes the first sub-electrode sheet (13) and the second sub-electrode sheet (14), the second electrode sheet (12) includes the first sub-electrode sheet (13) and the second sub-electrode sheet (14), and the number of turns of the first sub-electrode sheet (13) in the first electrode sheet (11) is equal to the number of turns of the first sub-electrode sheet (13) in the second electrode sheet (12).

25. The battery cell according to claim 20, wherein, The electrode sheet (10) includes a current collector (15) and an active material layer (16), the active material layer (16) is located on at least one surface of the current collector (15), and the first sub-electrode sheet (13) and the second sub-electrode sheet (14) satisfy one of the following conditions: The first sub-electrode sheet (13) includes the current collector (15), and the second sub-electrode sheet (14) includes the current collector (15) and the active material layer (16); Both the first sub-electrode sheet (13) and the second sub-electrode sheet (14) include the current collector (15) and the active material layer (16), and the thickness of the active material layer (16) of the first sub-electrode sheet (13) is less than the thickness of the active material layer (16) of the second sub-electrode sheet (14).

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

27. An electrical device, characterized in that, The electrical device includes the battery device according to claim 26, and the battery device is used to provide electric energy.

28. An energy storage device, characterized in that, The energy storage device includes the battery device according to claim 26, and the battery device is used to store electric energy.

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