Battery cells, battery packs, electrical devices and energy storage devices

Abstract

This application provides a battery cell, a battery device, an electrical device, and an energy storage device, belonging to the field of batteries. The battery cell includes an anode sheet and a cathode sheet. The anode sheet includes a first anode coating, a second anode coating, and an anode current collector. The first anode coating is located on a first anode surface, and the second anode coating is located on a second anode surface. The cathode sheet includes a first cathode coating, a second cathode coating, and a cathode current collector. The first cathode coating is located on a first cathode surface, and the second cathode coating is located on a second cathode surface. At least in the bending region of the wound body, the solid content of the second anode coating is greater than the solid content of the first anode coating, and / or the solid content of the second cathode coating is greater than the solid content of the first cathode coating. The battery cell provided in this application can reduce the possibility of lithium plating and improve the reliability of the battery cell.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell, battery device, power supply device, and energy storage device. Background Technology

[0002] Energy conservation and emission reduction are key to sustainable social development. Rechargeable batteries, with their ability to store and release energy as needed, are widely used in various electrical devices and energy storage systems, and are an important component in promoting energy transition and sustainable development. For the new energy industry, battery technology is a crucial factor in its development.

[0003] A battery cell includes a cathode and an anode. After the anode and cathode are stacked and wound into a spiral structure, in the bending region, the arc length of the convex surface of the anode is smaller than the arc length of the concave surface of the adjacent cathode. Furthermore, the closer to the inner ring, the greater the difference between the arc length of the convex surface of the anode and the arc length of the concave surface of the adjacent cathode. This results in insufficient lithium intercalation capability of the convex surface of the anode towards the concave surface of the adjacent cathode, making it easier for lithium plating to occur on the anode in the inner ring of the spiral structure, thus affecting the reliability of the battery cell. Utility Model Content

[0004] This application aims to at least solve one of the technical problems existing in the background art. To this end, one object of this application is to provide a battery cell, battery device, power consumption device, and energy storage device to reduce the possibility of lithium plating and improve the reliability of the battery cell.

[0005] An embodiment of the first aspect of this application provides a battery cell, the battery cell comprising: an anode sheet including a first anode coating, a second anode coating, and an anode current collector, the anode current collector having opposing first anode surfaces and second anode surfaces, the first anode coating being located on the first anode surface, and the second anode coating being located on the second anode surface; and a cathode sheet including a first cathode coating, a second cathode coating, and a cathode current collector, the cathode current collector having opposing first cathode surfaces and second cathode surfaces, the first cathode coating being located on the first cathode surface, and the second cathode coating being located on the second cathode surface, the anode sheet and the cathode sheet being stacked and wound to form a wound body, the wound body having a bending region, the first anode surface in each turn of the anode sheet being located closer to the winding center of the wound body than the second anode surface, and the first cathode surface in each turn of the cathode sheet being located closer to the winding center of the wound body than the second cathode surface; wherein, at least in the bending region, the solid content of the second anode coating is greater than the solid content of the first anode coating, and / or the solid content of the second cathode coating is greater than the solid content of the first cathode coating.

[0006] In the technical solution of this application embodiment, within the bending region, the first anode surface is concave, the second anode surface is convex, the first cathode surface is concave, and the second cathode surface is convex; that is, the first anode surface is opposite to the second cathode surface, and vice versa. When the convex surface of the anode sheet faces the concave surface of the cathode sheet, i.e., the second anode surface faces the first cathode surface, if the solid content of the second anode coating is greater than the solid content of the first anode coating, the capacity of the second anode coating is increased, reducing the capacity difference between the second anode coating and the adjacent first cathode coating, thus improving the lithium intercalation capability of the anode sheet. Similarly, if the solid content of the second cathode coating is greater than the solid content of the first cathode coating, the capacity of the first cathode coating is reduced, reducing the capacity difference between the first cathode coating and the adjacent second anode coating, also improving the lithium intercalation capability of the anode sheet. Both of these situations can reduce the possibility of lithium plating and improve the reliability of the battery cell.

[0007] In some embodiments, the second anode coating includes: a first sub-anode coating located on the surface of the second anode; and a second sub-anode coating located on the surface of the second anode, wherein the second sub-anode coating and the first sub-anode coating are alternately arranged along the winding direction of the winding body, and the second sub-anode coating is located in the bending region; wherein the solid content of the first sub-anode coating is equal to the solid content of the first anode coating, and the solid content of the second sub-anode coating is greater than the solid content of the first anode coating. In areas where the anode and cathode sheets are not bent, there is no problem of insufficient lithium intercalation capacity of the anode sheet due to differences in arc length. Therefore, setting the first sub-anode coating in the non-bending region eliminates the need to increase the solid content of the first sub-anode coating, saving resources. Setting the second sub-anode coating in the bending region increases the solid content of the second sub-anode coating, improves the lithium intercalation capacity of the anode sheet, and improves the reliability of the battery cell.

[0008] In some embodiments, the solid content of the first anode coating and the solid content of the second sub-anode coating satisfy at least one of the following conditions: the solid content of the first anode coating is greater than or equal to 40% and less than or equal to 60%; the solid content of the second sub-anode coating is greater than or equal to 50% and less than or equal to 70%. Setting the solid content of the first anode coating within the above range ensures that it contains sufficient anodic active material to improve the lithium intercalation capability of the anode sheet, while also containing sufficient conductive agents, binders, and other components to improve the electrode conductivity and ensure strong adhesion between the anodic active material and the anode current collector. Setting the solid content of the second sub-anode coating within the above range further enhances the lithium intercalation capability of the anode sheet, while also improving the electrode conductivity and the adhesion between the anodic active material and the anode current collector.

[0009] In some embodiments, the ratio of the porosity of the second sub-anode coating to the porosity of the first sub-anode coating is greater than or equal to 0.6 and less than or equal to 0.95. Since the porosity of the second sub-anode coating is less than that of the first sub-anode coating, the second sub-anode coating contains more solids, resulting in a higher solid content than the first sub-anode coating.

[0010] In some embodiments, the porosity of the first sub-anode coating is greater than or equal to 20% and less than or equal to 55%. Setting the porosity of the first sub-anode coating within this range provides sufficient three-phase interface (active material, electrolyte, conductive agent), which is beneficial for electron conduction, ion diffusion, and electrochemical reactions. Porosity within this range allows the battery cell to achieve a better balance in terms of energy density, charge / discharge efficiency, and cycle life, thus satisfying the optimization and balance of various performance characteristics of the battery cell.

[0011] In some embodiments, along the winding direction of the winding body, the width of the second sub-anode coating is greater than or equal to 5 mm and less than or equal to 300 mm. By setting the width of the second sub-anode coating within the above range, the width of the second sub-anode coating can be adjusted according to the number of turns of the second sub-anode coating in the anode sheet, so that the second sub-anode coating can cover the bending area and improve the lithium intercalation capability of the anode sheet in the bending area.

[0012] In some embodiments, the first cathode coating includes: a first sub-cathode coating located on the surface of the first cathode, the first sub-cathode coating being located in the bending region; and a second sub-cathode coating located on the surface of the first cathode, the second sub-cathode coating and the first sub-cathode coating being alternately arranged along the winding direction of the winding body; wherein the solid content of the first sub-cathode coating is less than the solid content of the second cathode coating, and the solid content of the second sub-cathode coating is equal to the solid content of the second cathode coating. In the non-bending region of the battery cell, neither the anode nor the cathode sheet is bent, and there is no lithium plating problem caused by different arc lengths. Therefore, setting the second sub-cathode coating in the non-bending region does not require changing the solid content of the second sub-cathode coating, reducing the impact on the specific capacity of the battery cell. Setting the first sub-cathode coating in the bending region reduces the solid content of the first sub-cathode coating, reduces the number of lithium ions extracted from the first sub-cathode coating, allows lithium ions to embed into the anode sheet, reduces the possibility of lithium plating, and improves the reliability of the battery cell.

[0013] In some embodiments, the solid content of the second cathode coating and the solid content of the first sub-cathode coating satisfy at least one of the following conditions: the solid content of the second cathode coating is greater than or equal to 60% and less than or equal to 80%; the solid content of the first sub-cathode coating is greater than or equal to 30% and less than or equal to 65%. Setting the solid content of the second cathode coating within the above range ensures that there is sufficient cathode active material in the second cathode coating to improve the specific capacity of the battery cell. Simultaneously, the second cathode coating contains sufficient conductive agents, binders, and other components to improve the conductivity of the electrode and ensure that the cathode active material can adhere firmly to the cathode current collector. Setting the solid content of the first sub-cathode coating within the above range reduces the possibility of lithium plating while preventing the solid content of the first sub-cathode coating from being too low, which would affect the specific capacity of the battery cell.

[0014] In some embodiments, the ratio of the porosity of the first sub-cathode coating to the porosity of the second sub-cathode coating is greater than or equal to 1.2 and less than or equal to 1.5. The porosity of the first sub-cathode coating is greater than that of the second sub-cathode coating, and the first sub-cathode coating contains less solids, resulting in a lower solid content in the first sub-cathode coating than in the second sub-cathode coating.

[0015] In some embodiments, the porosity of the second sub-cathode coating is greater than or equal to 15% and less than or equal to 50%. Setting the porosity of the second sub-cathode coating within this range provides sufficient three-phase interface (active material, electrolyte, conductive agent), which is beneficial for electron conduction, ion diffusion, and electrochemical reactions. Porosity within this range allows for a better balance in energy density, charge / discharge efficiency, and cycle life of the battery cell, thus achieving optimization and balance among various performance characteristics.

[0016] In some embodiments, along the winding direction of the winding body, the width of the first sub-cathode coating is greater than or equal to 5 mm and less than or equal to 300 mm. By setting the width of the first sub-cathode coating within the above range, the width of the first sub-cathode coating can be adjusted according to the number of turns of the first sub-cathode coating in the cathode sheet, so that the first sub-cathode coating can cover the bending area, thereby increasing the likelihood of lithium plating occurring in the bending area.

[0017] In some embodiments, the thickness of the first anode coating is equal to the thickness of the second anode coating. By keeping the thickness of the second anode coating constant, making the thickness of the second anode coating equal to the thickness of the first anode coating, the manufacturing process is simplified.

[0018] In some embodiments, the thickness of the first cathode coating is equal to the thickness of the second cathode coating. By keeping the thickness of the first cathode coating constant, making the thickness of the first cathode coating equal to the thickness of the second cathode coating, the manufacturing process is simple.

[0019] An embodiment of the second aspect of this application provides a battery device comprising a single battery cell according to any of the above embodiments.

[0020] An embodiment of the third aspect of this application provides an electrical device that includes the battery device described in the above embodiments, the battery device being used to provide electrical energy.

[0021] An embodiment of the fourth aspect of this application provides an energy storage device, which includes the battery device in the above embodiments, the battery device being used to store electrical energy.

[0022] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0023] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0024] Figure 1 This is an end view of a portion of the wound body according to some embodiments of this application;

[0025] Figure 2 This is a partially enlarged view of the end face of a portion of the wound body according to some embodiments of this application;

[0026] Figure 3 This is another partially enlarged view of the end face of a portion of the wound body according to some embodiments of this application;

[0027] Figure 4 This is an exploded structural diagram of a battery cell provided in some embodiments of this application;

[0028] Figure 5 A cross-sectional view of an anode sheet provided in an embodiment of this application;

[0029] Figure 6 A cross-sectional view of a cathode sheet provided in an embodiment of this application;

[0030] Figure 7 This is an exploded view of the battery device according to some embodiments of this application;

[0031] Figure 8 This is a schematic diagram of the structure of a vehicle according to some embodiments of this application.

[0032] Explanation of reference numerals in the attached figures:

[0033] 10. Anode sheet; 11. First anode coating; 12. Second anode coating; 121. First sub-anode coating; 122. Second sub-anode coating; 13. Anode current collector; 131. First anode surface; 132. Second anode surface; 20. Cathode sheet; 21. First cathode coating; 211. First sub-cathode coating; 212. Second sub-cathode coating; 22. Second cathode coating; 23. Cathode current collector; 231. First cathode surface; 232. Second cathode surface; 30. Separator; 100. Battery cell; 101. End cap; 1011. Electrode terminal; 102. Housing; 103. Electrode assembly; 1031. Tab; 200. Housing; 2001. First part; 2002. Second part; 1000. Battery assembly; 2000. Controller; 3000. Motor; 01. Vehicle. Detailed Implementation

[0034] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0036] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0037] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0038] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0039] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0040] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0041] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0042] Currently, the application of rechargeable batteries is becoming increasingly widespread, judging from market trends. They are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also extensively in various electronic devices, such as electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As the application areas of rechargeable batteries continue to expand, the market demand is also constantly increasing.

[0043] Currently, the application of rechargeable batteries is becoming increasingly widespread, judging from market trends. They are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also extensively in various electronic devices, such as electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As the application areas of rechargeable batteries continue to expand, the market demand is also constantly increasing.

[0044] In some cases, anode and cathode sheets are stacked and wound together to form a wound body. In the bending area of ​​this wound body, the closer to the winding center, the more prone the anode sheet is to lithium plating. This is because the closer to the winding center, the more likely the actual CB value is to be less than 1. The CB value refers to the capacity of the anode active material layer divided by the capacity of the cathode active material layer. When the CB value is less than 1, the anode sheet's lithium intercalation capability is insufficient; lithium ions extracted from the cathode cannot be completely embedded within the anode sheet, leading to lithium plating on the anode surface. Lithium plating can cause problems such as battery cell capacity decay and internal short circuits, affecting the performance of the battery cells.

[0045] Based on the above considerations, a battery cell is designed, comprising an anode sheet and a cathode sheet. The anode sheet and cathode sheet are stacked and wound to form a wound body. The anode sheet includes a first anode coating, a second anode coating, and an anode current collector. The anode current collector has opposing first and second anode surfaces, with the first anode coating located on the first anode surface and the second anode coating located on the second anode surface. The cathode sheet includes a first cathode coating, a second cathode coating, and a cathode current collector, with opposing first and second cathode surfaces, the first cathode coating located on the first cathode surface and the second cathode coating located on the second cathode surface. The wound body has a bending region. In each turn of the anode sheet, the first anode surface is positioned closer to the winding center of the wound body than the second anode surface, and in each turn of the cathode sheet, the first cathode surface is positioned closer to the winding center of the wound body than the second cathode surface. Specifically, at least in the bending region, the solid content of the second anode coating is greater than that of the first anode coating, and / or the solid content of the second cathode coating is greater than that of the first cathode coating. The battery cell provided in this application embodiment can reduce the possibility of lithium plating and improve the reliability of the battery cell.

[0046] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices or energy storage devices such as vehicles, ships, or aircraft. A power system comprising the battery cells and batteries disclosed in this application can be used to construct such an electrical device or energy storage device.

[0047] An embodiment of this application provides a battery cell, which includes an anode plate 10 and a cathode plate 20. Figure 1This is a partial end view of the wound body according to some embodiments of this application. The anode sheet 10 and the cathode sheet 20 are stacked and wound together to form the wound body.

[0048] Figure 2 This is a partially enlarged view of the end face of a portion of the wound body according to some embodiments of this application. Figure 3 This is another partially enlarged view of an end face of a portion of the wound body according to some embodiments of this application. See also Figure 2 and Figure 3 The anode sheet 10 includes a first anode coating 11, a second anode coating 12, and an anode current collector 13. The anode current collector 13 has a first anode surface 131 and a second anode surface 132 opposite to each other. The first anode coating 11 is located on the first anode surface 131, and the second anode coating 12 is located on the second anode surface 132.

[0049] The cathode sheet 20 includes a first cathode coating 21, a second cathode coating 22, and a cathode current collector 23. The cathode current collector 23 has a first cathode surface 231 and a second cathode surface 232 opposite to each other. The first cathode coating 21 is located on the first cathode surface 231, and the second cathode coating 22 is located on the second cathode surface 232.

[0050] The wound body has a bending region. In each turn of the anode sheet 10, the first anode surface 131 is positioned closer to the winding center of the wound body than the second anode surface 132. Similarly, in each turn of the cathode sheet 20, the first cathode surface 231 is positioned closer to the winding center of the wound body than the second cathode surface 232. At least in the bending region, the solid content of the second anode coating 12 is greater than that of the first anode coating 11, and / or the solid content of the second cathode coating 22 is greater than that of the first cathode coating 21.

[0051] Figure 4 This is an exploded structural diagram of a battery cell provided in some embodiments of this application. For example... Figure 4 The battery cell 100 also includes an end cap 101, a housing 102, an electrode assembly 103, and other functional components.

[0052] End cap 101 refers to a component that covers the opening of housing 102 to isolate the internal environment of battery cell 100 from the external environment. The shape of end cap 101 can be adapted to the shape of housing 102 to fit it. Optionally, end cap 101 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 101 is not easily deformed under pressure and impact, giving battery cell 100 higher structural strength and improved safety performance. Functional components such as electrode terminals 1011 can be provided on end cap 101. Electrode terminals 1011 can be used for electrical connection with electrode assembly 103 for outputting or inputting electrical energy into battery cell 100. In some embodiments, end cap 101 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 100 reaches a threshold. The material of end cap 101 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating element may be provided on the inner side of the end cap 101. The insulating element can be used to isolate the electrical connection components within the housing 102 from the end cap 101 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0053] The housing 102 is a component used to cooperate with the end cap 101 to form the internal environment of the battery cell 100. This internal environment can accommodate the electrode assembly 103, electrolyte, and other components. The housing 102 and the end cap 101 can be independent components. An opening can be provided on the housing 102, and the end cap 101 can be used to close the opening to form the internal environment of the battery cell 100. Alternatively, the end cap 101 and the housing 102 can be integrated. Specifically, the end cap 101 and the housing 102 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 102, the end cap 101 closes the housing 102. The housing 102 can be of various shapes and sizes, such as cuboid, cylindrical, or hexagonal prism. Specifically, the shape of the housing 102 can be determined according to the specific shape and size of the electrode assembly 103. The housing 102 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, or plastic.

[0054] Electrode assembly 103 is the component in the battery cell 100 where electrochemical reactions occur. The housing 102 may contain one or more electrode assemblies 103. An anode plate 10 and a cathode plate 20 are stacked and wound to form a wound body. After further processing, the wound body forms the electrode assembly 103, and a separator 30 is typically provided between the cathode plate 20 and the anode plate 10. The portions of the cathode plate 20 and the anode plate 10 containing active material constitute the main body of the electrode assembly 103, while the portions of the cathode plate 20 and the anode plate 10 without active material each constitute a tab 1031. The cathode tab and the anode tab may be located together at one end of the main body or at opposite ends of the main body. During the charging and discharging process of the battery device, the cathode active material and the anode active material react with the electrolyte, and the tab 1031 connects to the electrode terminals 1011 to form a current circuit.

[0055] In the embodiments of this application, the anode current collector 13 may be made of copper.

[0056] In the embodiments of this application, the anodic active slurry is coated on the first anode surface 131 and the second anode surface 132 of the anode current collector 13, forming a first anode coating 11 on the first anode surface 131 and a second anode coating 12 on the second anode surface 132.

[0057] In the embodiments of this application, the anodic active slurry is composed of an anodic active material, a conductive agent, a binder, a functional additive, and a solvent. Exemplarily, when preparing the anodic active slurry, the percentage of active material in the second anodic coating 12 can be increased by changing the amount of active material added or the amount of solvent added, so that the percentage of active material in the second anodic coating 12 is greater than the percentage of active material in the first anodic coating 11, thereby achieving a higher solid content in the second anodic coating 12 than in the first anodic coating 11.

[0058] In the embodiments of this application, the cathode current collector 23 may be made of aluminum.

[0059] In the embodiments of this application, the cathode active slurry is coated on the first cathode surface 231 and the second cathode surface 232 of the cathode current collector 23, forming a first cathode coating 21 on the first cathode surface 231 and a second cathode coating 22 on the second cathode surface 232.

[0060] In the embodiments of this application, the cathode active slurry is composed of an anolyte, a conductive agent, a binder, a functional additive, and a solvent. Exemplarily, when preparing the cathode active slurry, the percentage of active material in the second cathode coating 22 can be increased by changing the amount of active material added or the amount of solvent added, thereby increasing the percentage of active material in the first cathode coating 21, and thus achieving a higher solid content in the second cathode coating 22 than in the first cathode coating 21.

[0061] The cathode plate 20 and the anode plate 10 can be spirally wound so that the resulting wound body has a spiral structure. Alternatively, the wound body formed by winding the cathode plate 20 and the anode plate 10 can have a racetrack structure.

[0062] The winding direction refers to the direction in which the winding is performed around the winding center of the winding body. The starting point of the winding direction is the winding center, and the ending point is the winding end.

[0063] The winding center refers to the central axis. The cathode plate 20 and the anode plate 10 are wound around the central axis to form the winding body.

[0064] In each turn of the anode sheet 10, the first anode surface 131 is positioned closer to the winding center of the winding body than the second anode surface 132. That is, the first anode surface 131 is recessed in the direction away from the winding center of the winding body, forming a concave surface, while the second anode surface 132 protrudes in the direction away from the winding center of the winding body, forming a convex surface. In each turn of the cathode sheet 20, the first cathode surface 231 is positioned closer to the winding center of the winding body than the second cathode surface 232. That is, the first cathode surface 231 is recessed in the direction away from the winding center of the winding body, forming a concave surface, while the second cathode surface 232 protrudes in the direction away from the winding center of the winding body, forming a convex surface.

[0065] For the case where the cathode plate 20 is located outside the anode plate 10 in two adjacent rings of cathode plates 20 and anode plates 10, see [reference needed]. Figure 2 The first cathode surface 231 of the cathode plate 20 is opposite to the second anode surface 132 of the anode plate 10. For the case where the anode plate 10 is located outside the cathode plate 20 in two adjacent rings of cathode plates 20 and anode plates 10, see [reference needed]. Figure 3 The second cathode surface 232 of the cathode plate 20 and the first anode surface 131 of the anode plate 10 are opposite each other.

[0066] At least in the bending region, the solid content of the second anode coating 12 is greater than the solid content of the first anode coating 11, and / or the solid content of the second cathode coating 22 is greater than the solid content of the first cathode coating 21. That is, at least in the bending region, the solid content of the second anode coating 12 is greater than the solid content of the first anode coating 11; or at least in the bending region, the solid content of the second cathode coating 22 is greater than the solid content of the first cathode coating 21; or at least in the bending region, the solid content of the second anode coating 12 is greater than the solid content of the first anode coating 11, and the solid content of the second cathode coating 22 is greater than the solid content of the first cathode coating 21.

[0067] In the embodiments of this application, the anode sheet 10 and the cathode sheet 20 are both wound into multiple turns from near the winding center to away from the winding center.

[0068] In some embodiments of this application, for the anode sheet 10, the solid content of the second anode coating 12 on the innermost ring of the anode sheet 10 located in the bending region may be greater than the solid content of the first anode coating 11; or the solid content of the second anode coating 12 on all rings of the anode sheet 10 located in the bending region may be greater than the solid content of the first anode coating 11; or the solid content of the second anode coating 12 on some rings of the anode sheet 10 located in the bending region may be greater than the solid content of the first anode coating 11.

[0069] In some embodiments of this application, for the cathode sheet 20, the solid content of the second cathode coating 22 on the innermost ring of the cathode sheet 20 located in the bending region may be greater than the solid content of the first cathode coating 21; or the solid content of the second cathode coating 22 on all rings of the cathode sheet 20 located in the bending region may be greater than the solid content of the first cathode coating 21; or the solid content of the second cathode coating 22 on some rings of the cathode sheet 20 located in the bending region may be greater than the solid content of the first cathode coating 21.

[0070] The solid content of the second anode coating 12 is greater than that of the first anode coating 11, which means that the capacity of the second anode coating 12 is greater than that of the first anode coating 11.

[0071] The solid content of the second cathode coating 22 is greater than that of the first cathode coating 21, which means that the capacity of the second cathode coating 22 is greater than that of the first cathode coating 21.

[0072] In the embodiments of this application, within the bending region, the first anode surface 131 is concave, the second anode surface 132 is convex, the first cathode surface 231 is concave, and the second cathode surface 232 is convex; that is, the first anode surface 131 and the second cathode surface 232 are opposite each other, and the second anode surface 132 and the first cathode surface 231 are opposite each other. When the convex surface of the anode sheet 10 is opposite the concave surface of the cathode sheet 20, that is, when the second anode surface 132 is opposite the first cathode surface 231, if the solid content of the second anode coating 12 is greater than the solid content of the first anode coating 11, the capacity of the second anode coating 12 is increased, the capacity difference between the second anode coating 12 and the adjacent first cathode coating 21 is reduced, and the lithium intercalation capability of the anode sheet 10 is improved. Similarly, if the solid content of the second cathode coating 22 is greater than the solid content of the first cathode coating 21, the capacity of the first cathode coating 21 is reduced, the capacity difference between the first cathode coating 21 and the adjacent second anode coating 12 is reduced, and the lithium intercalation capability of the anode sheet 10 is also improved. Both of these approaches can reduce the likelihood of lithium plating and improve the reliability of individual battery cells.

[0073] As for the case where the concave surface of the anode plate 10 is opposite to the convex surface of the cathode plate 20, that is, the case where the first anode surface 131 is opposite to the second cathode surface 232, the arc length of the first anode surface 131 is originally greater than the arc length of the second cathode surface 232. Generally, there is no problem with insufficient anode lithium intercalation capability, and the solid content of the first anode coating 11 and the solid content of the second cathode coating 22 can be maintained.

[0074] According to some embodiments of this application, see Figure 2 and Figure 3 The second anode coating 12 includes a first sub-anode coating 121 and a second sub-anode coating 122. Both the first sub-anode coating 121 and the second sub-anode coating 122 are located on the second anode surface 132. The second sub-anode coating 122 and the first sub-anode coating 121 are arranged alternately along the winding direction of the winding body, with the second sub-anode coating 122 located in the bending region. The solid content of the first sub-anode coating 121 is equal to the solid content of the first anode coating 11, and the solid content of the second sub-anode coating 122 is greater than the solid content of the first anode coating 11.

[0075] In some embodiments of this application, the wound body includes two bent areas and one non-bent area. The two bent areas are located on opposite sides of the non-bent area and are connected to it. The cathode sheet 20 and the anode sheet 10 are wound to form the wound body. Assuming the wound anode sheet 10 is unwound, the portions of the anode sheet 10 located in the bent areas and the portions located in the non-bent areas are arranged alternately. For example, the two bent areas of the wound body are two semi-circular regions on both sides, and the non-bent area is a square region in the middle.

[0076] In the embodiments of this application, the second sub-anode coating 122 is located in the bending region, and the first sub-anode coating 121 can be located in either the non-bending region or the bending region.

[0077] Since the anode sheet 10 is wound into multiple turns, the second sub-anode coating 122 can be located on the second anode surface 132 of the innermost turn of the anode sheet 10 within the bending area. In this case, the first sub-anode coating 121 is located in both the bending area and the non-bending area. The second sub-anode coating 122 can be located on the second anode surface 132 of all turns of the anode sheet 10 within the bending area. In this case, the first sub-anode coating 121 is located in the non-bending area. The second sub-anode coating 122 can be located on the second anode surface 132 of some turns of the anode sheet 10 within the bending area. In this case, the first sub-anode coating 121 is located in both the bending area and the non-bending area.

[0078] In the non-bending region of the battery cell, neither the anode sheet 10 nor the cathode sheet 20 is bent. Therefore, there is no issue of insufficient lithium intercalation capability of the anode sheet 10 due to differences in arc length. Thus, the first sub-anode coating 121 is placed in the non-bending region without increasing its solid content, saving resources. The second sub-anode coating 122 is placed in the bending region, increasing its solid content and improving the lithium intercalation capability of the anode sheet 10, thereby enhancing the reliability of the battery cell.

[0079] According to some embodiments of this application, the solid content of the first anode coating 11 and the solid content of the second sub-anode coating 122 satisfy at least one of the following conditions: the solid content of the first anode coating 11 is greater than or equal to 40% and less than or equal to 60%; the solid content of the second sub-anode coating 122 is greater than or equal to 50% and less than or equal to 70%.

[0080] For example, the solid content of the first anode coating 11 is greater than or equal to 40% and less than or equal to 60%; or the solid content of the second sub-anode coating 122 is greater than or equal to 50% and less than or equal to 70%; or the solid content of the first anode coating 11 is greater than or equal to 40% and less than or equal to 60%, while the solid content of the second sub-anode coating 122 is greater than or equal to 50% and less than or equal to 70%.

[0081] For example, the solid content of the first anode coating 11 is 40%, and the solid content of the second sub-anode coating 122 can be 50%; or the solid content of the first anode coating 11 is 40%, and the solid content of the second sub-anode coating 122 can be 45%; or the solid content of the first anode coating 11 is 35%, and the solid content of the second sub-anode coating 122 can be 50%; or the solid content of the first anode coating 11 is 50%, and the solid content of the second sub-anode coating 122 can be 60%; or the solid content of the first anode coating 11 is 50%, and the solid content of the second sub-anode coating 122 can be 80%; or the solid content of the first anode coating 11 is 60%, and the solid content of the second sub-anode coating 122 can be 65%; or the solid content of the first anode coating 11 is 60%, and the solid content of the second sub-anode coating 122 can be 75%.

[0082] The solid content of the first anode coating 11 is set within the aforementioned range, ensuring sufficient anodic active material in the first anode coating 11 to improve the lithium intercalation capability of the anode sheet 10. Simultaneously, the first anode coating 11 contains sufficient conductive agent, binder, and other components to improve the electrode conductivity and ensure strong adhesion between the anodic active material and the anode current collector 13. The solid content of the second sub-anode coating 122 is also set within the aforementioned range, increasing its solid content to enhance the lithium intercalation capability of the anode sheet 10, while simultaneously improving the electrode conductivity and the adhesion between the anodic active material and the anode current collector 13.

[0083] In the embodiments of this application, the areal density of the second sub-anode coating 122 is greater than the areal density of the first anode coating 11, and the areal density of the first sub-anode coating 121 is equal to the areal density of the first anode coating 11.

[0084] For example, the areal density of the second sub-anodine coating 122 is greater than or equal to 150 mg / 1540.25 mm. 2 And less than or equal to 250mg / 1540.25mm 2 The areal density of the first anolyte coating 11 is greater than or equal to 130 mg / 1540.25 mm. 2 And less than or equal to 220mg / 1540.25mm 2 .

[0085] According to some embodiments of this application, the ratio of the porosity of the second sub-anode coating 122 to the porosity of the first sub-anode coating 121 is greater than or equal to 0.6 and less than or equal to 0.95.

[0086] For example, the ratio of the porosity of the second sub-anode coating 122 to the porosity of the first sub-anode coating 121 is equal to 0.6; or the ratio of the porosity of the second sub-anode coating 122 to the porosity of the first sub-anode coating 121 is equal to 0.7; or the ratio of the porosity of the second sub-anode coating 122 to the porosity of the first sub-anode coating 121 is equal to 0.75; or the ratio of the porosity of the second sub-anode coating 122 to the porosity of the first sub-anode coating 121 is equal to 0.8; or the ratio of the porosity of the second sub-anode coating 122 to the porosity of the first sub-anode coating 121 is equal to 0.85; or the ratio of the porosity of the second sub-anode coating 122 to the porosity of the first sub-anode coating 121 is equal to 0.9; or the ratio of the porosity of the second sub-anode coating 122 to the porosity of the first sub-anode coating 121 is equal to 0.95.

[0087] The porosity of the second sub-anode coating 122 is less than that of the first sub-anode coating 121. The second sub-anode coating 122 contains more solids, which makes the solid content of the second sub-anode coating 122 greater than that of the first sub-anode coating 121.

[0088] According to some embodiments of this application, the porosity of the first sub-anodine coating 121 is greater than or equal to 20% and less than or equal to 55%.

[0089] For example, the porosity of the first sub-anode coating 121 is equal to 20%; or the porosity of the first sub-anode coating 121 is equal to 30%; or the porosity of the first sub-anode coating 121 is equal to 40%; or the porosity of the first sub-anode coating 121 is equal to 50%; or the porosity of the first sub-anode coating 121 is equal to 55%.

[0090] Given a fixed porosity for the first sub-anode coating 121, the appropriate porosity for the second sub-anode coating 122 can be determined by combining the ratio of the porosity of the second sub-anode coating 122 to that of the first sub-anode coating 121.

[0091] The anode or cathode coating on the electrode needs to have a certain porosity. During the charging and discharging process of a battery cell, lithium ions need to shuttle back and forth between the positive and negative electrodes. Porosity provides a fast transport channel for lithium ions, helping to shorten the diffusion path of lithium ions, improve ion conduction efficiency, and thus enhance the charge and discharge performance of the battery cell. An active material coating with suitable porosity allows the electrolyte to fully penetrate into the active material, ensuring sufficient contact between the active material and the electrolyte, thereby increasing the reaction area and improving the specific capacity of the battery cell. During the charging and discharging process of a battery cell, the active material undergoes volume expansion and contraction. Porosity provides a buffer space for this volume change, reducing stress between active material particles and between the active material and the current collector, reducing the possibility of electrode structure damage, and improving the cycle stability of the battery cell.

[0092] If the porosity of the anode or cathode coating is too small, resulting in a relatively low number of pores, the transport channels for lithium ions within the coating are limited. This leads to increased ion diffusion resistance, slower lithium ion migration during charging and discharging, and reduced charge / discharge efficiency. Furthermore, the electrolyte cannot adequately wet the active material, preventing it from fully participating in the electrochemical reaction and affecting the specific capacity of the battery cell. The stress generated by volume changes during charging and discharging is difficult to release, potentially causing active material particles to detach from the current collector or leading to coating cracks, thus impacting the cycle life of the battery cell.

[0093] If the porosity of the anode or cathode coating is too high, although the number of ion transport channels increases and the electrolyte wettability improves, the actual loading of active material will be relatively reduced, the amount of electricity that the battery cell can store will decrease, and the energy density will be lower. The structural strength of the anode or cathode coating will also be reduced, making it prone to deformation and damage during the extrusion and winding processes in the battery cell manufacturing process. Moreover, during the charging and discharging process, the connection between active material particles will become weak, which will also reduce the cycle stability and mechanical properties of the battery cell.

[0094] Setting the porosity of the first sub-anode coating 121 within the aforementioned range provides sufficient three-phase interface (active material, electrolyte, conductive agent), which is beneficial for electron conduction, ion diffusion, and electrochemical reactions. Porosity within this range allows the battery cell to achieve a better balance in terms of energy density, charge / discharge efficiency, and cycle life, thus optimizing and balancing various performance characteristics.

[0095] According to some embodiments of this application, along the winding direction of the winding body, the width L1 of the second sub-anodine coating 122 is greater than or equal to 5 mm and less than or equal to 300 mm.

[0096] Since the anode plate 10 is wound into multiple turns, the arc length of the anode plate 10 in the bending area is different for different turns. The innermost turn of the anode plate 10 has the shortest arc length in the bending area, and the outermost turn of the anode plate 10 has the longest arc length in the bending area.

[0097] By setting the width L1 of the second sub-anode coating 122 within the above range, the width L1 of the second sub-anode coating 122 can be adjusted according to the number of turns of the second sub-anode coating 122 in the anode sheet 10, so that the second sub-anode coating 122 can cover the bending area, thereby improving the lithium insertion capability of the anode sheet 10 in the bending area.

[0098] According to some embodiments of this application, see Figure 2 and Figure 3 The first cathode coating 21 includes a first sub-cathode coating 211 and a second sub-cathode coating 212. Both the first sub-cathode coating 211 and the second sub-cathode coating 212 are located on the surface 231 of the first cathode. The first sub-cathode coating 211 is located in the bending region, and the second sub-cathode coating 212 and the first sub-cathode coating 211 are arranged alternately along the winding direction of the winding body. The solid content of the first sub-cathode coating 211 is less than the solid content of the second cathode coating 22, and the solid content of the second sub-cathode coating 212 is equal to the solid content of the second cathode coating 22.

[0099] Assuming the wound cathode sheet 20 is unwound, the portion of the cathode sheet 20 located in the bending area and the portion located in the non-bending area are arranged alternately.

[0100] In the embodiments of this application, the first sub-cathode coating 211 is located in the bending region, and the second sub-cathode coating 212 can be located in the non-bending region or in the bending region.

[0101] Since the cathode sheet 20 is wound into multiple turns, the first sub-cathode coating 211 can be located on the innermost first cathode surface 231 within the bending area of ​​the cathode sheet 20, at which time the second sub-cathode coating 212 is located in both the bending area and the non-bending area; the first sub-cathode coating 211 can be located on the first cathode surface 231 of all turns within the bending area of ​​the cathode sheet 20, at which time the second sub-cathode coating 212 is located in the non-bending area; the first sub-cathode coating 211 can be located on the first cathode surface 231 of some turns within the bending area of ​​the cathode sheet 20, at which time the second sub-cathode coating 212 is located in both the bending area and the non-bending area.

[0102] In the non-bending region of the battery cell, neither the anode plate 10 nor the cathode plate 20 is bent, eliminating the lithium plating problem caused by differences in arc length. Therefore, the second sub-cathode coating 212 can be placed in the non-bending region without changing its solid content, thus reducing its impact on the battery cell's specific capacity. In the bending region, the first sub-cathode coating 211 is placed. Reducing the solid content of the first sub-cathode coating 211 decreases the number of lithium ions released from it, allowing the lithium ions to embed into the anode plate 10, reducing the likelihood of lithium plating and improving the battery cell's reliability.

[0103] According to some embodiments of this application, the solid content of the second cathode coating 22 and the solid content of the first sub-cathode coating 211 satisfy at least one of the following conditions: the solid content of the second cathode coating 22 is greater than or equal to 60% and less than or equal to 80%; the solid content of the first sub-cathode coating 211 is greater than or equal to 30% and less than or equal to 65%.

[0104] For example, the solid content of the second cathode coating 22 is greater than or equal to 60% and less than or equal to 80%; or the solid content of the first sub-cathode coating 211 is greater than or equal to 30% and less than or equal to 65%; or the solid content of the second cathode coating 22 is greater than or equal to 60% and less than or equal to 80%, while the solid content of the first sub-cathode coating 211 is greater than or equal to 30% and less than or equal to 65%.

[0105] For example, the solid content of the second cathode coating 22 is 60%, and the solid content of the first sub-cathode coating 211 is 55%; or the solid content of the second cathode coating 22 is 60%, and the solid content of the first sub-cathode coating 211 is 25%; or the solid content of the second cathode coating 22 is 70%, and the solid content of the first sub-cathode coating 211 is 60%; or the solid content of the second cathode coating 22 is 70%, and the solid content of the first sub-cathode coating 211 is 50%; or the solid content of the second cathode coating 22 is 80%, and the solid content of the first sub-cathode coating 211 is 65%; or the solid content of the second cathode coating 22 is 85%, and the solid content of the first sub-cathode coating 211 is 65%.

[0106] The solid content of the second cathode coating 22 is set within the above-mentioned range to ensure that there is sufficient cathode active material in the second cathode coating 22, thereby increasing the specific capacity of the battery cell. Simultaneously, the second cathode coating 22 contains sufficient conductive agents, binders, and other components to improve the electrode conductivity and ensure that the cathode active material adheres firmly to the cathode current collector 23. The solid content of the first sub-cathode coating 211 is set within the above-mentioned range to reduce the solid content of the first sub-cathode coating 211, thereby reducing the possibility of lithium plating, while also preventing the solid content of the first sub-cathode coating 211 from being too low, which would affect the specific capacity of the battery cell.

[0107] In the embodiments of this application, the areal density of the first sub-cathode coating 211 is less than the areal density of the second cathode coating 22, and the areal density of the second sub-cathode coating 212 is equal to the areal density of the second cathode coating 22.

[0108] For example, the areal density of the first sub-cathode coating 211 is greater than or equal to 150 mg / 1540.25 mm. 2 And less than or equal to 300mg / 1540.25mm 2 The areal density of the second cathode coating 22 is greater than or equal to 250 mg / 1540.25 mm. 2 And less than or equal to 400mg / 1540.25mm 2 .

[0109] According to some embodiments of this application, the ratio of the porosity of the first sub-cathode coating 211 to the porosity of the second sub-cathode coating 212 is greater than or equal to 1.2 and less than or equal to 1.5.

[0110] For example, the ratio of the porosity of the first sub-cathode coating 211 to the porosity of the second sub-cathode coating 212 is equal to 1.2; or the ratio of the porosity of the first sub-cathode coating 211 to the porosity of the second sub-cathode coating 212 is equal to 1.3; or the ratio of the porosity of the first sub-cathode coating 211 to the porosity of the second sub-cathode coating 212 is equal to 1.35; or the ratio of the porosity of the first sub-cathode coating 211 to the porosity of the second sub-cathode coating 212 is equal to 1.4; or the ratio of the porosity of the first sub-cathode coating 211 to the porosity of the second sub-cathode coating 212 is equal to 1.5.

[0111] The porosity of the first sub-cathode coating 211 is greater than that of the second sub-cathode coating 212. The amount of solids in the first sub-cathode coating 211 is less, which makes the solid content of the first sub-cathode coating 211 less than that of the second sub-cathode coating 22.

[0112] According to some embodiments of this application, the porosity of the second sub-cathode coating 212 is greater than or equal to 15% and less than or equal to 50%.

[0113] For example, the porosity of the second sub-cathode coating 212 is equal to 15%; or the porosity of the second sub-cathode coating 212 is equal to 20%; or the porosity of the second sub-cathode coating 212 is equal to 25%; or the porosity of the second sub-cathode coating 212 is equal to 30%; or the porosity of the second sub-cathode coating 212 is equal to 35%; or the porosity of the second sub-cathode coating 212 is equal to 40%; or the porosity of the second sub-cathode coating 212 is equal to 50%.

[0114] Given a fixed porosity for the second sub-cathode coating 212, the appropriate porosity for the first sub-cathode coating 211 can be determined by combining the ratio of the porosity of the first sub-cathode coating 211 to the porosity of the second sub-cathode coating 212.

[0115] Setting the porosity of the second cathode coating 212 within the aforementioned range provides sufficient three-phase interface (active material, electrolyte, conductive agent), which is beneficial for electron conduction, ion diffusion, and electrochemical reactions. Within this porosity range, the battery cell achieves a better balance in terms of energy density, charge / discharge efficiency, and cycle life, thus optimizing and balancing various performance characteristics.

[0116] According to some embodiments of this application, along the winding direction of the winding body, the width L2 of the first sub-cathode coating 211 is greater than or equal to 5 mm and less than or equal to 300 mm.

[0117] Since the cathode sheet 20 is wound into multiple turns, the arc length of the cathode sheet 20 in the bending area is different for different turns. The innermost turn of the cathode sheet 20 has the shortest arc length in the bending area, and the outermost turn of the cathode sheet 20 has the longest arc length in the bending area.

[0118] By setting the width L2 of the first sub-cathode coating 211 within the aforementioned range, the width L2 of the first sub-cathode coating 211 can be adjusted according to the number of turns of the first sub-cathode coating 211 in the cathode sheet 20, so that the first sub-cathode coating 211 can cover the bending area, thereby increasing the possibility of lithium plating occurring in the bending area.

[0119] According to some embodiments of this application, Figure 5 A cross-sectional view of an anode sheet provided in an embodiment of this application. See also... Figure 5 The thickness D11 of the first anode coating 11 is equal to the thickness of the second anode coating 12.

[0120] When the second anode coating 12 includes a first sub-anode coating 121 and a second sub-anode coating 122, the thickness D121 of the first sub-anode coating 121 is equal to the thickness D11 of the first anode coating 11, and the thickness D122 of the second sub-anode coating 122 is equal to the thickness D11 of the first anode coating 11.

[0121] Without changing the thickness of the second anode coating 12, the thickness of the second anode coating 12 is equal to the thickness D11 of the first anode coating 11, making the manufacturing process simple.

[0122] According to some embodiments of this application, Figure 6 This is a cross-sectional view of a cathode sheet provided in an embodiment of this application. See also... Figure 6 The thickness of the first cathode coating 21 is equal to the thickness D22 of the second cathode coating 22.

[0123] When the first cathode coating 21 includes a first sub-cathode coating 211 and a second sub-cathode coating 212, the thickness D22 of the second cathode coating 22 is equal to the thickness D211 of the first sub-cathode coating 211, and the thickness D22 of the second cathode coating 22 is equal to the thickness D212 of the second sub-cathode coating 212.

[0124] Without changing the thickness of the first cathode coating 21, the thickness of the first cathode coating 21 is equal to the thickness D22 of the second cathode coating 22, making the manufacturing process simple.

[0125] For example, after mixing the anodic active material with a conductive agent, a binder and a functional additive in a certain proportion, different amounts of solvent are added and stirred to obtain two anodic active slurries. The anodic active slurry with a smaller amount of solvent is coated on the second anode surface 132 to form a second anode coating 12, and the anodic active slurry with a larger amount of solvent is coated on the first anode surface 131 to form a first anode coating 11.

[0126] For example, graphite (anodic active material), carbon black (conductive agent), and binder (CMC (sodium carboxymethyl cellulose) or SBR (styrene-butadiene rubber)) are mixed in a mass ratio of 96.5:2:1.5, and different volumes of deionized water solutions are added and stirred to obtain two types of anodic active slurries. The stirring speed is 1000 r / min, and the stirring time is 45 min.

[0127] An anodic active slurry with a higher solvent content is coated on the first anode surface 131 to form a first anode coating 11, and simultaneously coated on the second anode surface 132 to form a first sub-anode coating 121. An anodic active slurry with a lower solvent content is coated on the second anode surface 132 to form a second sub-anode coating 122.

[0128] For example, cathode active material is mixed with conductive agent, binder and functional additive in proportion, and different amounts of solvent are added to obtain two cathode active slurries. The cathode active slurry with less solvent is coated on the second cathode surface 232 to form a second cathode coating 22, and the anode active slurry with more solvent is coated on the first cathode surface 231 to form a first cathode coating 21.

[0129] For example, two cathode active slurries were prepared by mixing cathode active materials LFP (lithium iron phosphate) or NCM (lithium nickel cobalt manganese oxide), conductive agent Super-P, and binder PVDF (polyvinylidene fluoride) in a mass ratio of 97:2:1, and then adding different volumes of NMP (N-methylpyrrolidone) solution and stirring. The stirring speed was 800 r / min and the stirring time was 60 min.

[0130] A cathode active slurry with a relatively small amount of solvent is coated on the second cathode surface 232 to form a second cathode coating 22, and simultaneously coated on the first cathode surface 231 to form a second sub-cathode coating 212. An anodic active slurry with a relatively large amount of solvent is coated on the first cathode surface 231 to form a first sub-cathode coating 211.

[0131] In the embodiments of this application, after coating is completed, cold pressing, slitting, and die cutting are performed to obtain unwound anode sheet 10 and cathode sheet 20.

[0132] The anode sheet 10 and the cathode sheet 20 are wound in the winding section. During winding, the second sub-anode coating 122 is controlled to be located on the convex surface of the bending area of ​​the anode sheet 10, and the first sub-cathode coating 211 is located on the concave surface of the bending area of ​​the cathode sheet 20. After subsequent assembly, welding, formation and aging processes, the final battery cell is obtained.

[0133] Take a mass of m1 of the stirred active slurry (anodic or cathodic active slurry), dry it in an oven at 100°C, and weigh the dried mass as m2. The ratio of m2 to m1 (m2 / m1) is the solid content of the active slurry, which is also the solid content of the coating formed by the active slurry.

[0134] Dry the electrode (anode 10 or cathode 20), and cut the dried electrode into standard small round pieces with an area of ​​S. Weigh the mass M of different coatings (first anode coating 11, first sub-anode coating 121, second sub-anode coating 122, first sub-cathode coating 211, second sub-cathode coating 212, or second cathode coating 22) under this surface area. The areal density of the coating is M / S.

[0135] The electrode samples were placed in a BET testing device, and the porosity of different coatings was obtained by nitrogen adsorption-desorption.

[0136] The battery cells were placed at 25°C, 1C CC, 1C DC for more than 1000 cls for full charge and discharge cycles to obtain capacity decay data. The number of cycles when the capacity decayed to 80% was recorded. The cells were then disassembled to observe whether lithium plating occurred at the corner interface, thus determining whether lithium plating had occurred in the battery cells. After long-cycle testing, conventional battery cells show obvious lithium plating in the bending area upon disassembly. However, the battery cells provided in this embodiment showed no lithium plating in the bending area interface after disassembly.

[0137] Embodiments of this application also provide a battery device, which includes a single battery cell from any of the above embodiments.

[0138] Battery cell 100 refers to the smallest unit that makes up battery device 1000. Figure 7 This is an exploded view of the battery device according to some embodiments of this application. See also: Figure 7 The battery device 1000 includes a battery cell 100 and a housing 200, with the battery cell 100 housed within the housing 200. The housing 200 provides a space for the battery cell 100 and can have various structures. In some embodiments, the housing 200 may include a first portion 2001 and a second portion 2002, which overlap each other, together defining a space for accommodating the battery cell 100. The second portion 2002 may be a hollow structure with one open end, and the first portion 2001 may be a plate-like structure, covering the open side of the second portion 2002 so that the first portion 2001 and the second portion 2002 together define the space. Alternatively, both the first portion 2001 and the second portion 2002 may be hollow structures with one open side, with the open side of the first portion 2001 covering the open side of the second portion 2002. Of course, the box 200 formed by the first part 2001 and the second part 2002 can be of various shapes, such as cylinder, cuboid, etc.

[0139] In the battery device 1000, there can be multiple battery cells 100, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 100 are connected in both series and parallel configurations. Multiple battery cells 100 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 100 is housed within the housing 200. Alternatively, the battery device 1000 can also consist of multiple battery cells 100 first connected in series, parallel, or in a mixed manner to form battery modules, and then these battery modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the housing 200. The battery device 1000 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 100.

[0140] 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 to these. The battery cell 100 can be cylindrical, flat, cuboid, or other shapes.

[0141] The battery device provided in this application embodiment has a low probability of lithium plating and high reliability.

[0142] An embodiment of this application also provides an electrical device, which includes the battery device in the above embodiments, and the battery device is used to provide electrical energy.

[0143] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0144] For ease of explanation, the following embodiments will be described using a vehicle as an example of an electrical device according to an embodiment of this application.

[0145] Please refer to Figure 8 , Figure 8 This is a schematic diagram of the structure of a vehicle provided in some embodiments of this application. Vehicle 01 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. A battery device 1000 is installed inside vehicle 01, and the battery device 1000 can be located at the bottom, front, or rear of vehicle 01. The battery device 1000 can be used to power vehicle 01; for example, the battery device 1000 can serve as the operating power source for vehicle 01. Vehicle 01 may also include a controller 2000 and a motor 3000. The controller 2000 is used to control the battery device 1000 to supply power to the motor 3000, for example, to meet the power needs of vehicle 01 during starting, navigation, and driving.

[0146] In some embodiments of this application, the battery device 1000 can not only serve as the operating power source for the vehicle 01, but also as the driving power source for the vehicle 01, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 01.

[0147] The electrical device provided in this application embodiment has a low probability of lithium plating and high reliability.

[0148] An embodiment of this application also provides an energy storage device, which includes the battery device in the above embodiments, and the battery device is used to store electrical energy.

[0149] Energy storage devices can be, but are not limited to, energy storage containers, energy storage cabinets, energy storage power stations, energy storage battery packs, or portable energy storage systems.

[0150] The energy storage device provided in this application embodiment has a low probability of lithium plating and high reliability.

[0151] Embodiments of this application provide a battery cell, which includes an anode sheet 10 and a cathode sheet 20. The anode sheet 10 and the cathode sheet 20 are stacked and wound together to form a wound body. The anode sheet 10 includes a first anode coating 11, a second anode coating 12, and an anode current collector 13. The anode current collector 13 has a first anode surface 131 and a second anode surface 132 facing each other. The first anode coating 11 is located on the first anode surface 131, and the second anode coating 12 is located on the second anode surface 132.

[0152] The cathode sheet 20 includes a first cathode coating 21, a second cathode coating 22, and a cathode current collector 23. The cathode current collector 23 has a first cathode surface 231 and a second cathode surface 232 opposite to each other. The first cathode coating 21 is located on the first cathode surface 231, and the second cathode coating 22 is located on the second cathode surface 232.

[0153] The winding body has a bending area. The first anode surface 131 in each turn of the anode sheet 10 is located closer to the winding center of the winding body than the second anode surface 132. The first cathode surface 231 in each turn of the cathode sheet 20 is located closer to the winding center of the winding body than the second cathode surface 232.

[0154] The second anode coating 12 includes a first sub-anode coating 121 and a second sub-anode coating 122. Both the first sub-anode coating 121 and the second sub-anode coating 122 are located on the first anode surface 131. The second sub-anode coating 122 and the first sub-anode coating 121 are arranged alternately along the winding direction of the winding body, with the second sub-anode coating 122 located in the bending region. The solid content of the first sub-anode coating 121 is equal to the solid content of the first anode coating 11, and the solid content of the second sub-anode coating 122 is greater than the solid content of the first anode coating 11. The solid content of the first anode coating 11 is greater than or equal to 40% and less than or equal to 60%; the solid content of the second sub-anode coating 122 is greater than or equal to 50% and less than or equal to 70%. The ratio of the porosity of the second sub-anode coating 122 to the porosity of the first sub-anode coating 121 is greater than or equal to 0.6 and less than or equal to 0.95. The porosity of the first sub-anode coating 121 is greater than or equal to 20% and less than or equal to 55%. Along the winding direction of the main body, the width L1 of the second sub-anode coating 122 is greater than or equal to 5 mm and less than or equal to 300 mm. The thickness D121 of the first sub-anode coating 121 is equal to the thickness D11 of the first anode coating 11, and the thickness D122 of the second sub-anode coating 122 is equal to the thickness D11 of the first anode coating 11.

[0155] The first cathode coating 21 includes a first sub-cathode coating 211 and a second sub-cathode coating 212. Both the first sub-cathode coating 211 and the second sub-cathode coating 212 are located on the first cathode surface 231. The first sub-cathode coating 211 is located in the bending region, and the second sub-cathode coating 212 and the first sub-cathode coating 211 are arranged alternately along the winding direction of the winding body. The solid content of the first sub-cathode coating 211 is less than the solid content of the second cathode coating 22, and the solid content of the second sub-cathode coating 212 is equal to the solid content of the second cathode coating 22. The solid content of the second cathode coating 22 is greater than or equal to 60% and less than or equal to 80%; the solid content of the first sub-cathode coating 211 is greater than or equal to 30% and less than or equal to 65%. The ratio of the porosity of the first sub-cathode coating 211 to the porosity of the second sub-cathode coating 212 is greater than or equal to 1.2 and less than or equal to 1.5. The porosity of the second sub-cathode coating 212 is greater than or equal to 15% and less than or equal to 50%. Along the winding direction of the winding body, the width L2 of the first sub-cathode coating 211 is greater than or equal to 5 mm and less than or equal to 300 mm. The thickness D22 of the second cathode coating 22 is equal to the thickness D211 of the first sub-cathode coating 211, and the thickness D22 of the second cathode coating 22 is equal to the thickness D212 of the second sub-cathode coating 212.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized by, The battery cell includes: An anode sheet (10) includes a first anode coating (11), a second anode coating (12), and an anode current collector (13), wherein the anode current collector (13) has a first anode surface (131) and a second anode surface (132) opposite to each other, the first anode coating (11) is located on the first anode surface (131), and the second anode coating (12) is located on the second anode surface (132); The cathode sheet (20) includes a first cathode coating (21), a second cathode coating (22), and a cathode current collector (23). The cathode current collector (23) has a first cathode surface (231) and a second cathode surface (232) opposite to each other. The first cathode coating (21) is located on the first cathode surface (231), and the second cathode coating (22) is located on the second cathode surface (232). The anode sheet (10) and the cathode sheet (20) are stacked and wound together to form a wound body. The wound body has a bending area. The first anode surface (131) in each turn of the anode sheet (10) is closer to the winding center of the wound body than the second anode surface (132). The first cathode surface (231) in each turn of the cathode sheet (20) is closer to the winding center of the wound body than the second cathode surface (232). Wherein, at least in the bending region, the solid content of the second anode coating (12) is greater than the solid content of the first anode coating (11), and / or the solid content of the second cathode coating (22) is greater than the solid content of the first cathode coating (21).

2. The battery cell of claim 1, wherein, The second anodic coating (12) includes: The first sub-anode coating (121) is located on the second anode surface (132); The second sub-anode coating (122) is located on the second anode surface (132). The second sub-anode coating (122) and the first sub-anode coating (121) are arranged alternately along the winding direction of the winding body. The second sub-anode coating (122) is located in the bending area. The solid content of the first sub-anode coating (121) is equal to the solid content of the first anode coating (11), and the solid content of the second sub-anode coating (122) is greater than the solid content of the first anode coating (11).

3. The battery cell of claim 2, wherein, The solid content of the first anode coating (11) and the solid content of the second sub-anode coating (122) satisfy at least one of the following conditions: The solid content of the first anodic coating (11) is greater than or equal to 40% and less than or equal to 60%. The second sub-anodine coating (122) has a solid content greater than or equal to 50% and less than or equal to 70%.

4. The battery cell according to claim 2 or 3, characterized in that, The ratio of the porosity of the second sub-anode coating (122) to the porosity of the first sub-anode coating (121) is greater than or equal to 0.6 and less than or equal to 0.

95.

5. The battery cell of claim 4, wherein, The porosity of the first sub-anodine coating (121) is greater than or equal to 20% and less than or equal to 55%.

6. The battery cell according to any one of claims 2 to 5, characterized in that, Along the winding direction of the winding body, the width of the second sub-anodine coating (122) is greater than or equal to 5 mm and less than or equal to 300 mm.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The first cathode coating (21) includes: A first sub-cathode coating (211) is located on the surface of the first cathode (231), and the first sub-cathode coating (211) is located in the bending region; The second sub-cathode coating (212) is located on the surface of the first cathode (231), and the second sub-cathode coating (212) and the first sub-cathode coating (211) are arranged alternately along the winding direction of the winding body; The solid content of the first sub-cathode coating (211) is less than the solid content of the second cathode coating (22), and the solid content of the second sub-cathode coating (212) is equal to the solid content of the second cathode coating (22).

8. The battery cell of claim 7, wherein, The solid content of the second cathode coating (22) and the solid content of the first sub-cathode coating (211) satisfy at least one of the following conditions: The solid content of the second cathode coating (22) is greater than or equal to 60% and less than or equal to 80%; The first sub-cathode coating (211) has a solid content greater than or equal to 30% and less than or equal to 65%.

9. The battery cell according to claim 7 or 8, characterized in that, The ratio of the porosity of the first sub-cathode coating (211) to the porosity of the second sub-cathode coating (212) is greater than or equal to 1.2 and less than or equal to 1.

5.

10. The battery cell of claim 9, wherein, The porosity of the second sub-cathode coating (212) is greater than or equal to 15% and less than or equal to 50%.

11. The battery cell according to any one of claims 7 to 10, characterized in that, Along the winding direction of the winding body, the width of the first sub-cathode coating (211) is greater than or equal to 5 mm and less than or equal to 300 mm.

12. The battery cell of any one of claims 1 to 11, wherein, The thickness of the first anode coating (11) is equal to the thickness of the second anode coating (12).

13. The battery cell of any one of claims 1 to 12, wherein, The thickness of the first cathode coating (21) is equal to the thickness of the second cathode coating (22).

14. A battery device characterized by comprising: The battery device comprises a battery cell as described in any one of claims 1 to 13.

15. An electrical device, comprising: The electrical device includes the battery device as described in claim 14, the battery device being used to provide electrical energy.

16. An energy storage device, characterized by The energy storage device includes the battery device as described in claim 14, the battery device being used to store electrical energy.

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