Battery monomer, battery and electric equipment

Abstract

The utility model provides a battery monomer, a battery and electric equipment, the battery monomer comprises an electrode assembly and a buffer member, and the electrode assembly comprises a first pole piece, a second pole piece and a separator; the first pole piece, the second pole piece and the separator are wound along the winding direction to form a winding body, and a center hole is formed in the center of the winding body along the winding axial direction; the buffer piece is at least partially arranged in the center hole, and the buffer piece is connected to the first pole piece and / or the second pole piece; in the embodiment of the invention, the buffer piece can support the first pole piece and the second pole piece in the central hole of the winding body, so that the problem that the first pole piece and the second pole piece are loosened in the innermost ring of the winding body can be effectively improved.

Description

Technical Field

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

[0002] Energy conservation and emission reduction are the keys to the sustainable development of the automotive industry. Electric vehicles have become an important part of the sustainable development of the automotive industry due to their energy-saving and environmental protection advantages. For electric vehicles, battery technology is an important factor related to their development.

[0003] A battery cell usually includes a housing, an electrode assembly and an electrolyte, and both the electrolyte and the electrode assembly are sealed in the housing. In the design of the electrode assembly, the winding form is a commonly used form; by placing the cathode electrode sheet, the anode electrode sheet and the separator at intervals and winding them around a winding needle to form a winding body. However, after the winding is completed and the winding core is removed from the winding body, since there is no support inside the winding body, the cathode electrode sheet and the anode electrode sheet in the inner circle of the winding body will become loose, resulting in an increase in the distance between the cathode electrode sheet and the anode electrode sheet, and further causing the problem of lithium deposition. Summary of the Utility Model

[0004] The purpose of the embodiments of the present application is to provide a battery cell, a battery and an electrical device, aiming to solve the problem that the electrode sheets in the winding body are prone to looseness, resulting in lithium deposition.

[0005] To achieve the above purpose, the technical solution adopted in the embodiments of the present application is:

[0006] In a first aspect, the embodiments of the present application provide a battery cell, including an electrode assembly and a buffer member. The electrode assembly includes a first electrode sheet, a second electrode sheet and a separator located between the first electrode sheet and the second electrode sheet; the first electrode sheet, the second electrode sheet and the separator are wound along the winding direction to form a winding body, and a central hole is formed along the winding axis at the center of the winding body; the winding direction is perpendicular to the winding axis; at least part of the buffer member is disposed in the central hole, and the buffer member is connected to the first electrode sheet and / or the second electrode sheet.

[0007] The beneficial effects of the embodiments of the present application: The battery cell provided by the embodiments of the present application is provided with at least part of the buffer member in the central hole of the winding body, and the buffer member is connected to the first electrode sheet and / or the second electrode sheet, so that the buffer member can support the first electrode sheet and the second electrode sheet in the central hole of the winding body to balance the expansion force generated during the charge and discharge process of the battery cell, effectively improving the problem that the first electrode sheet and the second electrode sheet become loose at the central hole of the winding body and reducing the probability of lithium deposition.

[0008] In some embodiments, a first electrode tab sequentially forms an empty foil area and a coating area along the winding direction, and the coating area is used for coating an active material layer; in a direction opposite to the winding direction, at least a part of the empty foil area extends beyond a second electrode tab, and a buffer member is connected to the empty foil area.

[0009] By adopting the above technical solution, the empty foil area and the coating area are sequentially formed on the first electrode tab along the winding direction, and at least a part of the empty foil area extends beyond the second electrode tab in a direction opposite to the winding direction. Thus, after the buffer member is connected to the empty foil area, when the first electrode tab, the second electrode tab, and the separator are wound along the winding direction to form a wound body, at least a part of the empty foil area can be located within the central hole, so that at least a part of the buffer member will also be located within the central hole, and further the buffer member can support the coating area of the first electrode tab and the second electrode tab.

[0010] In some embodiments, the empty foil area is wound along the winding direction to form at least one empty foil bending portion; the buffer member is connected to the empty foil bending portion.

[0011] By adopting the above technical solution, the buffer member can be on the empty foil bending portion and support the coating area of the first electrode tab and the second electrode tab, so as to increase the corner gap at the bending portion of the coating area of the first electrode tab and the second electrode tab, thereby reducing the probability of brittle fracture of the coating area of the first electrode tab and the second electrode tab.

[0012] In some embodiments, the empty foil area is wound along the winding direction and alternately forms at least one empty foil straight portion and at least one empty foil bending portion; the buffer member is connected to the empty foil straight portion and the empty foil bending portion.

[0013] By adopting the above technical solution, the buffer member can be connected to the empty foil straight portion and the empty foil bending portion at the same time, and under the action of the buffer member supporting the coating area of the first electrode tab and the second electrode tab, the connection stability of the buffer member is better.

[0014] In some embodiments, the empty foil area forms at least one empty foil straight portion along the winding direction; the buffer member is connected to the empty foil straight portion.

[0015] By adopting the above technical solution, the buffer member can support the coating area of the first electrode tab and the second electrode tab on the surface of the empty foil straight portion to balance the acting force of the expansion force.

[0016] In some embodiments, the buffer member includes a first buffer portion, and the first buffer portion is arranged inside the empty foil area.

[0017] By adopting the above technical solution, the first buffer portion is arranged inside the empty foil area, so that the first buffer portion can support the first electrode tab and the second electrode tab at the innermost side of the wound body.

[0018] In some embodiments, the buffer member includes a second buffer portion disposed outside the empty foil area.

[0019] By adopting the above technical solution, the second buffer portion can be disposed outside the empty foil area, thereby improving the support effect on the first electrode sheet and the second electrode sheet.

[0020] In some embodiments, the first buffer portion is disposed opposite to the second buffer portion.

[0021] By adopting the above technical solution, the first buffer portion and the second buffer portion are respectively located inside and outside the empty foil area and are disposed opposite to each other. Thus, the first buffer portion and the second buffer portion together have a better effect of supporting the first electrode sheet and the second electrode sheet.

[0022] In some embodiments, in the winding direction, the length o of the buffer member is less than or equal to the length p of the empty foil area.

[0023] By adopting the above technical solution, the length o of the buffer member is set to be less than or equal to the length p of the empty foil area to reduce the influence of the overlong buffer member extending into the coating area on the coated active material layer, and further reduce the influence on the energy density of the battery cell.

[0024] In some embodiments, in the winding direction, a gap is formed between the end of the buffer member and the starting end of the coating area.

[0025] By adopting the above technical solution, a gap is formed between the end of the buffer member and the starting end of the coating area, that is, the buffer member does not extend onto the coating area, thereby reducing the influence of the buffer member on the active material layer and further reducing the influence on the energy density of the battery cell.

[0026] In some embodiments, the first electrode sheet is a cathode electrode sheet and the second electrode sheet is an anode electrode sheet.

[0027] By adopting the above technical solution, the buffer pad can be connected to the cathode electrode sheet and / or the anode electrode sheet to achieve the support effect.

[0028] In some embodiments, the first electrode sheet is an anode electrode sheet and the second electrode sheet is a cathode electrode sheet.

[0029] By adopting the above technical solution, the buffer pad can be connected to the cathode electrode sheet and / or the anode electrode sheet to achieve the support effect.

[0030] In some embodiments, the first electrode sheet includes a single-sided coating area and a double-sided coating area arranged in sequence in the winding direction, and the buffer member is disposed inside the single-sided coating area; in the direction opposite to the winding direction, at least a part of the single-sided coating area extends beyond the second electrode sheet.

[0031] By adopting the above technical solution, the inner side of the single-sided coating area is used to connect the buffer member to achieve a supporting effect. At the same time, the active material layer can be coated on the outer side of the single-sided coating area. Thus, the active material layer on the single-sided coating area can be fully utilized to improve the energy density of the battery cell.

[0032] In some embodiments, in the winding axial direction, the width of the buffer member is less than or equal to the width of the winding body, and the buffer member does not protrude outside the central hole.

[0033] By adopting the above technical solution, setting the buffer member not to protrude outside the central hole in the winding axial direction can effectively reduce the influence of the buffer member on the winding operation.

[0034] In some embodiments, in the winding axial direction, the winding body has a width a, and the buffer member has a width b, where 0 ≤ a - b ≤ 2 mm.

[0035] By adopting the above technical solution, in the direction perpendicular to the winding direction, the width of the buffer member can be set to be the same as the width of the winding body to within 2 mm narrower than the width of the winding body; if the width of the buffer member is too wide, it may cause an impact on the winding process, and if the width of the buffer member is too narrow, it may cause stress streaks to form on the first pole piece and the second pole piece.

[0036] In some embodiments, 0 ≤ a - b ≤ 1 mm.

[0037] By adopting the above technical solution, by further limiting the difference between the width of the winding body and the width of the buffer member to be greater than or equal to zero and less than or equal to 1 mm, the probability of stress streaks forming on the first pole piece and the second pole piece can be further reduced.

[0038] In some embodiments, the buffer member has a compression ratio c, 30% ≤ c ≤ 90%.

[0039] By adopting the above technical solution, the compression ratio of the buffer member is limited to be greater than or equal to 30% and less than or equal to 90%. Thus, within this range, while the buffer member has a better supporting effect, the influence of the buffer member on the occupied space is relatively low.

[0040] In some embodiments, 50% ≤ c ≤ 70%.

[0041] By adopting the above technical solution, the compression ratio of the buffer member is further limited to be greater than or equal to 50% and less than or equal to 70%. Thus, within this range, the supporting effect of the buffer member is further improved, and the influence of the buffer member on the occupied space is further reduced.

[0042] In some embodiments, the buffer member has a thickness d, 0.5 mm ≤ d ≤ 4 mm.

[0043] By adopting the above technical solution, the thickness d of the buffer is limited to be greater than or equal to 0.5 mm and less than or equal to 4 mm, so that the buffer has sufficient thickness to achieve the supporting effect. At the same time, the influence of the buffer on the space occupied by the wound body is relatively low.

[0044] In some embodiments, 0.5 mm ≤ d ≤ 2 mm.

[0045] By adopting the above technical solution, the thickness d of the buffer is further limited to be greater than or equal to 0.5 mm and less than or equal to 2 mm, so as to further reduce the influence of the buffer on the space occupied by the wound body.

[0046] In some embodiments, at least one end of the buffer is formed with a chamfer structure in the winding direction.

[0047] By adopting the above technical solution, by providing a chamfer structure on the buffer, the probability of the end of the buffer squeezing the first pole piece and the second pole piece to generate indentation during the cold pressing and shaping process of the wound body can be effectively reduced.

[0048] In some embodiments, the buffer includes any one of a polypropylene buffer, a polyethylene buffer, a plexiglass buffer, a polyester buffer, and a polycarbonate buffer.

[0049] By adopting the above technical solution, using any one of a polypropylene buffer, a polyethylene buffer, a plexiglass buffer, a polyester buffer, and a polycarbonate buffer as the buffer can achieve the supporting effect on the first pole piece and the second pole piece.

[0050] In some embodiments, the buffer is connected to the separator.

[0051] By adopting the above technical solution, the buffer is connected to the first pole piece and / or the second pole piece, and the buffer is set to be connected to the separator, thereby effectively improving the stability of the buffer and reducing the probability of the buffer being misaligned during the winding process.

[0052] In a second aspect, an embodiment of the present application further provides a battery, including a box body and the battery cell as described above, and the battery cell is accommodated in the box body.

[0053] Beneficial effects of the embodiments of the present application: The battery provided by the embodiments of the present application includes the above battery cell. On the basis of the relatively good reliability of the above battery cell, the battery also has relatively good reliability.

[0054] In a third aspect, an embodiment of the present application further provides an electrical device, including the battery as described above, and the battery is used to provide electrical energy.

[0055] Advantages of the embodiments of the present application: The electrical device provided by the embodiments of the present application includes the above-mentioned battery. On the basis that the reliability of the above-mentioned battery is relatively good, the electrical device also has relatively good reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0057] Figure 1 Structural schematic diagram of the vehicle provided by the embodiments of the present application;

[0058] Figure 2 Explosion diagram of the battery provided by the embodiments of the present application;

[0059] Figure 3 Exploded structural schematic diagram of the battery cell provided by the embodiments of the present application;

[0060] Figure 4 Structural schematic diagram of the first winding body provided by the embodiments of the present application;

[0061] Figure 5 For Figure 4 Partial enlarged schematic diagram at position A;

[0062] Figure 6 Structural schematic diagram of the first pole piece in the unfolded state of the first winding body provided by the embodiments of the present application;

[0063] Figure 7 Structural schematic diagram of a connection structure between the first pole piece and the buffer member of the first winding body provided by the embodiments of the present application;

[0064] Figure 8 Structural schematic diagram of another connection structure between the first pole piece and the buffer member of the first winding body provided by the embodiments of the present application;

[0065] Figure 9 Structural schematic diagram of the second winding body provided by the embodiments of the present application;

[0066] Figure 10 For Figure 9 Partial enlarged schematic diagram at position B;

[0067] Figure 11 Structural schematic diagram of the third winding body provided by the embodiments of the present application;

[0068] Figure 12 For Figure 11Partial enlarged schematic view at position C;

[0069] Figure 13 is Figure 11 Partial enlarged schematic view at position D;

[0070] Figure 14 Schematic view of the connection structure between the first pole piece and the buffer member of the third winding body provided by the embodiment of the present application;

[0071] Figure 15 Schematic view of the winding operation of the third winding body provided by the embodiment of the present application.

[0072] Among them, the reference numerals in the figure are as follows:

[0073] 1000, vehicle;

[0074] 100, battery; 200, controller; 300, motor;

[0075] 10, box body; 11, first part; 12, second part;

[0076] 20, battery cell; 21, end cover; 21a, electrode terminal; 22, housing;

[0077] 23, electrode assembly; 23a, tab; 23b, winding body; 23b1, central hole;

[0078] 231, first pole piece; 231a, empty foil area; 231a1, empty foil straight part; 231a2, empty foil bent part; 231b, coating area; 231c, active material layer; 231d, single-sided coating area; 231f, double-sided coating area;

[0079] 232, second pole piece; 233, separator;

[0080] 24, buffer member; 241, chamfer structure; 24a, first buffer part; 24b, second buffer part;

[0081] 30, core;

[0082] X, winding direction; Y, winding axis. Detailed implementation manners

[0083] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application, and should not be construed as limiting the present application.

[0084] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0085] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0086] In the present application, unless otherwise clearly specified and limited, the terms "mounted", "connected", "connected to", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may 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 present application can be understood according to specific circumstances.

[0087] Currently, from the perspective of the development of the market situation, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, but also widely used in electric transportation tools such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as military equipment and aerospace. With the continuous expansion of the application fields of power batteries, the market demand is also continuously increasing.

[0088] A battery cell generally includes a housing, an electrode assembly, and an electrolyte, and both the electrolyte and the electrode assembly are sealed in the housing. In the design of the electrode assembly, the winding form is a commonly used form; by placing the cathode electrode sheet, the anode electrode sheet, and the separator at intervals and winding them around a winding needle to form a wound body. However, after the winding is completed and the winding needle is withdrawn from the wound body, since there is no support inside the wound body, the cathode electrode sheet and the anode electrode sheet in the inner circle of the wound body will become loose, which will lead to an increase in the distance between the cathode electrode sheet and the anode electrode sheet, and further cause the problem of lithium deposition.

[0089] Based on the above considerations, in order to solve the problem that the electrode sheets in the winding body are prone to looseness, resulting in lithium plating, a battery cell is designed. By winding the first electrode sheet, the second electrode sheet and the separator along the winding direction to form a winding body, and a central hole is formed along the winding axis at the center of the winding body, at least part of the buffer member is arranged in the central hole, and the buffer member is connected to the first electrode sheet and / or the second electrode sheet. Thus, the buffer member can support the first electrode sheet and the second electrode sheet in the central hole of the winding body, effectively improving the problem of looseness of the first electrode sheet and the second electrode sheet. At the same time, it can also balance the expansion force generated during the charge and discharge process of the battery cell due to expansion, so as to effectively reduce the probability of lithium plating.

[0090] The battery cell disclosed in the embodiments of the present application can be used in electrical equipment using the battery as a power source or various energy storage systems using the battery as an energy storage element. The electrical equipment can be, but is not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc. The spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0091] For the convenience of description in the following embodiments, a vehicle 1000, which is an electrical equipment in an embodiment of the present application, is taken as an example for description.

[0092] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of the vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or an extended-range electric vehicle, etc. A battery 100 is arranged inside the vehicle 1000, and the battery 100 can be arranged at the bottom, the head or the tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000. For example, the battery 100 can be used as the operating power source of the vehicle 1000. The vehicle 1000 can also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, for the working power requirements during the start, navigation and driving of the vehicle 1000.

[0093] In some embodiments of the present application, the battery 100 can not only be used as the operating power source of the vehicle 1000, but also be used as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0094] Please refer to Figure 2 , Figure 2Exploded view of the battery 100 provided by some embodiments of the present application. The battery 100 includes a box body 10 and battery cells 20, and the battery cells 20 are accommodated in the box body 10. Among them, the box body 10 is used to provide an accommodation space for the battery cells 20, and the box body 10 can adopt various structures. In some embodiments, the box body 10 may include a first part 11 and a second part 12, the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define an accommodation space for accommodating the battery cells 20. The second part 12 may be a hollow structure with one end open, and the first part 11 may be a plate-like structure. The first part 11 covers the open side of the second part 12 so that the first part 11 and the second part 12 jointly define an accommodation space; the first part 11 and the second part 12 may also both be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box body 10 formed by the first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0095] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 can be connected in series, parallel or in a hybrid connection. A hybrid connection means that there are both series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, parallel or in a hybrid connection together, and then the whole formed by the multiple battery cells 20 is accommodated in the box body 10; of course, the battery 100 can also be in the form that multiple battery cells 20 are first connected in series, parallel or in a hybrid connection to form battery modules, and then the multiple battery modules are connected in series, parallel or in a hybrid connection to form a whole and are accommodated in the box body 10. The battery 100 may further include other structures. For example, the battery 100 may further include a busbar component for realizing electrical connection among the multiple battery cells 20.

[0096] Among them, each battery cell 20 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 not limited thereto. The battery cell 20 can be in the shape of a cylinder, a flat body, a cuboid or other shapes, etc.

[0097] Please refer to Figure 3 , Figure 3 Schematic exploded view of the battery cell 20 provided by some embodiments of the present application. The battery cell 20 refers to the smallest unit that makes up the battery 100. As Figure 3 shown, the battery cell 20 includes a housing (including an end cap 21 and a shell 22), an electrode assembly 23 and other functional components.

[0098] The end cap 21 refers to a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the housing 22 to fit the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 21 is not easily deformed when subjected to extrusion and collision, enabling the battery cell 20 to have higher structural strength and improved reliability. Functional components such as electrode terminals 21a can be provided on the end cap 21. The electrode terminals 21a can be used for electrical connection with the electrode assembly 23 to output or input the electrical energy of the battery cell 20. In some embodiments, a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold can also be provided on the end cap 21. The material of the end cap 21 can also be various. For example, the material of the end cap 21 can be but is not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating member can also be provided on the inner side of the end cap 21. The insulating member can be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc.

[0099] The housing 22 is a component for cooperating with the end cap 21 to form the internal environment of the battery cell 20. Among them, the formed internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 is covered at the opening to form the internal environment of the battery cell 20. Without limitation, the end cap 21 and the housing 22 can also be integrated. Specifically, the end cap 21 and the housing 22 can first form a common connection surface before other components are inserted into the housing. When it is necessary to encapsulate the inside of the housing 22, the end cap 21 is then covered on the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the housing 22 can be various. For example, the housing 22 can be but is not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0100] The electrode assembly 23 is a component in the battery cell 20 where an electrochemical reaction occurs. The housing 22 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or laminating an anode plate and a cathode plate, and usually a separator, such as a separator film, etc., is provided between the anode plate and the cathode plate. The parts of the anode plate and the cathode plate with active materials constitute the main body of the electrode assembly 23, and the parts of the anode plate and the cathode plate without active materials respectively constitute the electrode tabs 23a. The anode electrode tab and the cathode electrode tab may be located together at one end of the main body or separately at both ends of the main body. During the charge and discharge process of the battery, the anode active material and the cathode active material react with the electrolyte, and the electrode tab 23a is connected to the electrode terminal 21a to form a current loop.

[0101] According to some embodiments of the present application, referring to Figure 3 and Figure 4 or Figure 9 or Figure 11 , embodiments of the present application provide a battery cell 20, including an electrode assembly 23 and a buffer member 24. The electrode assembly 23 includes a first electrode plate 231, a second electrode plate 232, and a separator 233 located between the first electrode plate 231 and the second electrode plate 232; the first electrode plate 231, the second electrode plate 232, and the separator 233 are wound along the winding direction X to form a wound body 23b, and a central hole 23b1 is formed along the winding axis Y at the center of the wound body 23b; the winding direction X is perpendicular to the winding axis Y; the buffer member 24 is at least partially disposed in the central hole 23b1, and the buffer member 24 is connected to the first electrode plate 231 and / or the second electrode plate 232.

[0102] Wherein, the first electrode plate 231 and the second electrode plate 232 can react in the electrolyte to form a current. It should be understood that one of the first electrode plate 231 and the second electrode plate 232 has a cathode active material (such as anions, etc.), and the other of the first electrode plate 231 and the second electrode plate 232 has an anode active material (such as cations, etc.). Thus, the cathode active material and the anode active material react in the electrolyte to form a current.

[0103] The winding direction X refers to the direction in which the first electrode plate 231, the separator 233, and the second electrode plate 232 are stacked in sequence and then wound. In some embodiments, the first electrode plate 231 and the second electrode plate 232 may be wound after being aligned at the starting end in the winding direction X, and the central hole 23b1 is formed by the electrode plates wound into the innermost circle. Or, in other embodiments, in the direction opposite to the winding direction X, the first electrode plate 231 may be wound beyond the second electrode plate 232, or the second electrode plate 232 may be wound beyond the first electrode plate 231, and the part by which the first electrode plate 231 extends is wound to the innermost circle of the wound body 23b.

[0104] The winding axis Y refers to the direction perpendicular to the winding direction X. After the first pole piece 231, the separator 233, and the second pole piece 232 are stacked in sequence, they are wound along the winding direction X and around the winding axis Y to form a wound body 23b. It can be understood that after the first pole piece 231, the separator 233, and the second pole piece 232 are stacked in sequence and wound around the bobbin 30 to form the wound body 23b. After the winding operation is completed, the bobbin 30 is withdrawn, and thus a hollow central hole 23b1 will be formed in the middle region of the wound body 23b, as Figure 15 shown.

[0105] The buffer member 24 is used to be disposed in the central hole 23b1 and support the first pole piece 231 and the second pole piece 232, so as to reduce the probability that the first pole piece 231 and the second pole piece 232 become loose into the central hole 23b1. Optionally, the buffer member 24 includes, but is not limited to, buffer pads, buffer layer bodies, buffer sheet bodies and other buffer support structures. The buffer member 24 can be connected and fixed to the first pole piece 231 and / or the second pole piece 232 by means of thermal lamination, adhesion, etc.

[0106] Wherein, the buffer member 24 is at least partially disposed in the central hole 23b1; optionally, the buffer member 24 can be completely accommodated in the central hole 23b1; or, the buffer member 24 can be partially accommodated in the central hole 23b1, and the other part of the buffer member 24 is connected between the second pole piece 232 and the first pole piece 231 and wound into the interior of the wound body 23b. The number of the buffer members 24 can be one, or the number of the buffer members 24 can be multiple, and the multiple buffer members 24 can be connected to the first pole piece 231 and / or the second pole piece 232 continuously or at intervals.

[0107] Exemplarily, in some embodiments, the buffer member 24 can be connected to the first pole piece 231, and at least part of the buffer member 24 is accommodated in the central hole 23b1; or, in some other embodiments, the buffer member 24 can be connected to the second pole piece 232, and at least part of the buffer member 24 is accommodated in the central hole 23b1; or, in other embodiments, the buffer member 24 can be connected to both the first pole piece 231 and the second pole piece 232 (for example, by folding the buffer member 24 so that the buffer member 24 bypasses the separator 233 and is connected to both the first pole piece 231 and the second pole piece 232), and at least part of the buffer member 24 is accommodated in the central hole 23b1.

[0108] The battery cell 20 provided by the embodiment of the present application is configured such that at least a part of a buffer member 24 is disposed within a central hole 23b1 of a wound body 23b, and the buffer member 24 is connected to the first electrode tab 231 and / or the second electrode tab 232. Thus, the buffer member 24 can support the first electrode tab 231 and the second electrode tab 232 within the central hole 23b1 of the wound body 23b to balance the expansion force generated due to expansion during the charge and discharge process of the battery cell 20, effectively improving the problem that the first electrode tab 231 and the second electrode tab 232 become loose at the central hole 23b1 of the wound body 23b and reducing the probability of lithium plating.

[0109] Please refer to Figures 4 to 6 and Figure 9 and Figure 10 , in some embodiments, the first electrode tab 231 sequentially forms an empty foil region 231a and a coated region 231b along the winding direction X, and the coated region 231b is used for coating an active material layer 231c; in the direction opposite to the winding direction X, at least a part of the empty foil region 231a extends beyond the second electrode tab 232, and the buffer member 24 is connected to the empty foil region 231a.

[0110] The first electrode tab 231 includes an empty foil region 231a and a coated region 231b; wherein, the coated region 231b is used for coating an active material layer 231c, and an electric current is formed by the reaction of the active material layer 231c with the second electrode tab 232 in the electrolyte.

[0111] Exemplarily, when the first electrode tab 231 is a cathode tab, an empty foil region 231a and a coated region 231b can be provided on the cathode tab, and the active material layer 231c coated on the coated region 231b is a cathode active material layer, as Figure 4 and Figure 5 shown. Alternatively, when the first electrode tab 231 is an anode tab, an empty foil region 231a and a coated region 231b can be provided on the anode tab, and the active material layer 231c coated on the coated region 231b is an anode active material layer, as Figure 9 and Figure 10 shown.

[0112] The empty foil region 231a refers to the part of the first electrode tab 231 where the active material layer 231c is not coated; the empty foil region 231a is used to connect the buffer member 24. Optionally, the buffer member 24 can be connected to the empty foil region 231a by means such as thermal lamination or adhesion to achieve fixation.

[0113] Among them, the empty foil area 231a and the coated area 231b are sequentially formed along the winding direction X, and the empty foil area 231a is formed upstream of the coated area 231b in the winding direction X; thus, during the winding operation, the empty foil area 231a can be wound into the innermost side of the winding body 23b, so that at least part of the empty foil area 231a will be within the central hole 23b1. Optionally, according to the different lengths of the empty foil area 231a in the winding direction X, the empty foil area 231a can form a winding structure of half a turn, one turn, one and a half turns, etc. within the central hole 23b1 of the winding body 23b. Exemplarily, in some specific embodiments, the first pole piece 231, the separator 233, and the second pole piece 232 are sequentially stacked, and in the winding direction X, the starting end of the second pole piece 232 is aligned with the starting end of the coated area 231b of the first pole piece 231, or the starting end of the second pole piece 232 is aligned with the middle area of the empty foil area 231a of the first pole piece 231; thus, at least part of the empty foil area 231a can extend into the central hole 23b1.

[0114] Exemplarily, when the first pole piece 231 encloses to form the central hole 23b1 (for example, the coated area 231b of the first pole piece 231 encloses to form the central hole 23b1), the empty foil area 231a can extend into the central hole 23b1, as Figure 9 shown; when the second pole piece 232 encloses to form the central hole 23b1, the empty foil area 231a of the first pole piece 231 can extend into the central hole 23b1, as Figure 4 shown.

[0115] The buffer member 24 is used to be connected to the empty foil area 231a and wind into the winding body 23b synchronously with the empty foil area 231a. Thus, at least part of the buffer member 24 can also be wound into the central hole 23b1 and support the first pole piece 231 and the second pole piece 232 within the central hole 23b1.

[0116] With such a setting, the empty foil area 231a and the coated area 231b are sequentially formed on the first pole piece 231 along the winding direction X, and at least part of the empty foil area 231a extends beyond the second pole piece 232 in the direction opposite to the winding direction X. Thus, after connecting the buffer member 24 to the empty foil area 231a, when the first pole piece 231, the second pole piece 232, and the separator 233 are wound along the winding direction X to form the winding body 23b, at least part of the empty foil area 231a can be located within the central hole 23b1, so that at least part of the buffer member 24 will also be located within the central hole 23b1, and further the buffer member 24 can achieve the supporting effect on the first pole piece 231 and the second pole piece 232.

[0117] Please refer to Figures 4 to 8 , in some embodiments, at least one empty foil bending portion 231a2 is formed on the empty foil area 231a along the winding direction X; the buffer member 24 is connected to the empty foil bending portion 231a2.

[0118] Understandably, during the winding process along the winding direction X, one or more empty foil bent portions 231a2 with a bent surface will be formed in the empty foil area 231a. Optionally, during the winding process along the winding direction X, a flat structure with a flat surface may also be formed in the empty foil area 231a.

[0119] Optionally, the buffer member 24 can be connected to either side surface of the empty foil bent portion 231a2, as Figure 8 shown; or, buffer members 24 can be connected to both opposite side surfaces of the empty foil bent portion 231a2, as Figure 7 shown.

[0120] It should be understood that at the location where the empty foil bent portion 231a2 is formed by winding the corresponding empty foil area 231a along the winding direction X, the coating area 231b of the first pole piece 231 and the second pole piece 232 will also wind and correspondingly form bent or even folded structures; there is a risk of brittle fracture at this location for the coating area 231b of the first pole piece 231 and the second pole piece 232.

[0121] With such a setting, the buffer member 24 is connected to the empty foil bent portion 231a2, so that the buffer member 24 can support the location where the coating area 231b of the first pole piece 231 and the second pole piece 232 correspondingly form a bent structure, in order to increase the corner clearance of the coating area 231b of the first pole piece 231 and the second pole piece 232 at this location, and thus can effectively reduce the probability of brittle fracture of the coating area 231b of the first pole piece 231 and the second pole piece 232 at this location.

[0122] Please refer to Figures 4 to 8 , in some embodiments, the empty foil area 231a winds along the winding direction X and alternately forms at least one empty foil flat portion 231a1 and at least one empty foil bent portion 231a2; the buffer member 24 is connected to the empty foil flat portion 231a1 and the empty foil bent portion 231a2.

[0123] Optionally, the buffer member 24 can be connected to either side surface of the empty foil flat portion 231a1 and the empty foil bent portion 231a2; or, buffer members 24 can be connected to both opposite side surfaces of the empty foil flat portion 231a1 and the empty foil bent portion 231a2.

[0124] Exemplarily, in the first type of implementation manner, the empty foil area 231a winds along the winding direction X and can form an empty foil flat portion 231a1 and an empty foil bent portion 231a2. The opposite ends of the empty foil bent portion 231a2 are respectively connected to the empty foil flat portion 231a1 and the coating area 231b, specifically as Figure 7 shown, and the buffer member 24 is connected to at least one side surface of the empty foil flat portion 231a1 and the empty foil bent portion 231a2.

[0125] Alternatively, in the second type of embodiment, the empty foil area 231a is wound along the winding direction X and can form two empty foil flat portions 231a1 and two empty foil bending portions 231a2. The opposite ends of one empty foil bending portion 231a2 are respectively connected to the two empty foil flat portions 231a1, and the other empty foil bending portion 231a2 is connected to the coating area 231b. Specifically, as Figure 8 shown, the buffer member 24 is connected to the inner surfaces of the empty foil flat portion 231a1 and the empty foil bending portion 231a2, that is, the surfaces of the empty foil flat portion 231a1 and the empty foil bending portion 231a2 facing the center of the central hole 23b1.

[0126] Alternatively, in the third type of embodiment, the empty foil area 231a is wound along the winding direction X and can form two empty foil flat portions 231a1 and two empty foil bending portions 231a2. The empty foil flat portions 231a1 and the empty foil bending portions 231a2 are alternately connected in sequence, and the last empty foil bending portion 231a2 is connected to the coating area 231b. The buffer member 24 can be connected to at least one side surface of the empty foil flat portion 231a1 and the empty foil bending portion 231a2.

[0127] Alternatively, in the fourth type of embodiment, the empty foil area 231a is wound along the winding direction X and can form more than two empty foil flat portions 231a1 and more than two empty foil bending portions 231a2. The buffer member 24 can be connected to at least one side surface of the empty foil flat portion 231a1 and the empty foil bending portion 231a2.

[0128] With such a setting, the buffer member 24 can be connected to the empty foil flat portion 231a1 and the empty foil bending portion 231a2 at the same time. Under the action of the buffer member 24 supporting the coating area 231b of the first pole piece 231 and the second pole piece 232, the connection stability of the buffer member 24 is better.

[0129] Please refer to Figures 4 to 8 , in some embodiments, the empty foil area 231a is formed with at least one empty foil flat portion 231a1 along the winding direction X; the buffer member 24 is connected to the empty foil flat portion 231a1.

[0130] Optionally, the buffer member 24 can be connected to any side surface of the empty foil flat portion 231a1; or, both opposite side surfaces of the empty foil flat portion 231a1 can be connected to the buffer member 24.

[0131] With such a setting, the buffer member 24 can support the coating area 231b of the first pole piece 231 and the second pole piece 232 on the surface of the empty foil flat portion 231a1 to balance the swelling force.

[0132] Please refer to Figure 5 and Figure 8, in some embodiments, the buffer member 24 includes a first buffer portion 24a, and the first buffer portion 24a is disposed inside the empty foil area 231a.

[0133] Herein, the inside of the empty foil area 231a refers to the side surface of the empty foil area 231a facing the central hole 23b1 of the winding body 23b.

[0134] The first buffer portion 24a is a part having buffer capacity and support capacity. The first buffer portion 24a can be but is not limited to a buffer pad structure, a buffer layer structure, a buffer sheet structure, etc.

[0135] With such an arrangement, the first buffer portion 24a is disposed inside the empty foil area 231a, so that the first buffer portion 24a can support the first pole piece 231 and the second pole piece 232 at the innermost side of the winding body 23b, thereby effectively supporting the first pole piece 231 and the second pole piece 232. Furthermore, it can effectively balance the expansion forces generated by the first pole piece 231 and the second pole piece 232, and can support the bent portions of the first pole piece 231 and the second pole piece 232 to reduce the probability of brittle fracture of the first pole piece 231 and the second pole piece 232.

[0136] Please refer to Figure 5 and Figure 7 , in some embodiments, the buffer member 24 includes a second buffer portion 24b, and the second buffer portion 24b is disposed outside the empty foil area 231a.

[0137] Herein, the outside of the empty foil area 231a refers to the side of the empty foil area 231a facing outside the winding body 23b.

[0138] The second buffer portion 24b is a part having buffer capacity and support capacity. The second buffer portion 24b can be but is not limited to a buffer pad structure, a buffer layer structure, a buffer sheet structure, etc.

[0139] With such an arrangement, when the first buffer portion 24a is disposed inside the empty foil area 231a and forms a support, the second buffer portion 24b can be disposed outside the empty foil area 231a, so that the second buffer portion 24b can cooperate with the first buffer portion 24a to support the coating area 231b of the first pole piece 231 and the second pole piece 232 at the same time, thereby further improving the support effect on the coating area 231b of the first pole piece 231 and the second pole piece 232.

[0140] Please refer to Figure 5 and Figure 7 , the first buffer portion 24a and the second buffer portion 24b are disposed opposite to each other.

[0141] Understandably, the relative arrangement of the first buffer portion 24a and the second buffer portion 24b means that in the thickness direction of the empty foil area 231a, the first buffer portion 24a and the second buffer portion 24b are opposite to each other, that is, the distribution positions of the first buffer portion 24a and the second buffer portion 24b in the thickness direction of the empty foil area 231a are substantially the same.

[0142] With such an arrangement, the first buffer portion 24a and the second buffer portion 24b are respectively located inside and outside the empty foil area 231a and are oppositely arranged. Thus, the first buffer portion 24a and the second buffer portion 24b are more effective in jointly supporting the first pole piece 231 and the second pole piece 232.

[0143] Please refer to Figure 5 and Figure 6 , in some embodiments, in the winding direction X, the length o of the buffer member 24 is less than or equal to the length p of the empty foil area 231a.

[0144] When the length o of the buffer member 24 is less than the length p of the empty foil area 231a, the starting end of the buffer member 24 in the winding direction X can be aligned with the starting end of the empty foil area 231a in the winding direction X for connection; or, the end section of the buffer member 24 in the winding direction X can be aligned with the end of the empty foil area 231a in the winding direction X for connection; or, the buffer member 24 can be connected between the starting end and the end of the empty foil area 231a in the winding direction X.

[0145] Among them, the starting end of the buffer member 24 in the winding direction X refers to the end side of the buffer member 24 facing away from the winding direction X; the end of the buffer member 24 in the winding direction X refers to the end side of the buffer member 24 facing the winding direction X.

[0146] Similarly, the starting end of the empty foil area 231a in the winding direction X refers to the end side of the empty foil area 231a facing away from the winding direction X; the end of the empty foil area 231a in the winding direction X refers to the end side of the empty foil area 231a facing the winding direction X.

[0147] With such an arrangement, the length o of the buffer member 24 is set to be less than the length p of the empty foil area 231a to reduce the influence of the overlong buffer member 24 extending into the coating area 231b on the active material layer 231c coated in the coating area 231b, and further reduce the influence on the energy density of the battery cell 20.

[0148] Please refer to Figures 4 to 6 , in some embodiments, in the winding direction X, a gap is formed between the end of the buffer member 24 and the starting end of the coating area 231b.

[0149] With such a setting, a gap is formed between the end of the buffer member 24 and the starting end of the coating area 231b, that is, the buffer member 24 does not extend onto the coating area 231b, thereby being able to reduce the influence of the buffer member 24 on the active material layer 231c, and further reducing the influence on the energy density of the battery cell 20.

[0150] Please refer to Figure 4 , in some embodiments, the first electrode tab 231 is a cathode electrode tab and the second electrode tab 232 is an anode electrode tab.

[0151] In this embodiment, the first electrode tab 231 can be a cathode electrode tab, that is, the first electrode tab 231 has cathode active material, so that the second electrode tab 232 has anode active material, and the second electrode tab 232 is an anode electrode tab.

[0152] Thus, the buffer member 24 can be connected to the cathode electrode tab and / or the anode electrode tab within the central hole 23b1 and form a support for the cathode electrode tab and the anode electrode tab.

[0153] Please refer to Figure 9 or Figure 11 , in some embodiments, the first electrode tab 231 is an anode electrode tab and the second electrode tab 232 is a cathode electrode tab.

[0154] In this embodiment, the first electrode tab 231 can be an anode electrode tab, that is, the first electrode tab 231 has anode active material, so that the second electrode tab 232 has cathode active material, and the second electrode tab 232 is a cathode electrode tab.

[0155] Thus, the buffer member 24 can be connected to the cathode electrode tab and / or the anode electrode tab within the central hole 23b1 and form a support for the cathode electrode tab and the anode electrode tab.

[0156] Please refer to Figures 11 to 14 , in some embodiments, the first electrode tab 231 includes a single-sided coating area 231d and a double-sided coating area 231f arranged in sequence along the winding direction X, and the buffer member 24 is arranged inside the single-sided coating area 231d; in the direction opposite to the winding direction X, at least a part of the single-sided coating area 231d extends beyond the second electrode tab 232.

[0157] Among them, the single-sided coating area 231d refers to the part of the first electrode tab 231 where one of the inner surface and the outer surface is coated with the active material layer 231c; the double-sided coating area 231f refers to the part of the first electrode tab 231 where both the inner surface and the outer surface are coated with the active material layer 231c.

[0158] The inner side of the single-sided coating area 231d refers to the side of the single-sided coating area 231d facing the inside of the central hole 23b1, and the outer side of the single-sided coating area 231d refers to the opposite side of the single-sided coating area 231d facing the outside of the winding body 23b. The inner side of the single-sided coating area 231d is connected to the buffer member 24. Thus, the outer side of the single-sided coating area 231d is coated with the active material layer 231c.

[0159] The single-sided coating area 231d and the double-sided coating area 231f are sequentially formed along the winding direction X, and the single-sided coating area 231d is formed upstream of the double-sided coating area 231f in the winding direction X. Thus, during the winding operation, the single-sided coating area 231d can be wound into the innermost side of the winding body 23b, so that at least a part of the single-sided coating area 231d will be inside the central hole 23b1 or enclose the central hole 23b1.

[0160] Optionally, according to the different lengths of the single-sided coating area 231d in the winding direction X, the single-sided coating area 231d can form a winding structure of multiple turns such as half a turn, one turn, one and a half turns, etc. inside the central hole 23b1 of the winding body 23b. Exemplarily, in some embodiments, the first pole piece 231, the separator 233, and the second pole piece 232 are stacked in sequence, and in the winding direction X, the starting end of the second pole piece 232 is substantially aligned with the starting end of the double-sided coating area 231f of the first pole piece 231, or the starting end of the double-sided coating area 231f extends beyond the starting end of the second pole piece 232 in the direction opposite to the winding direction X. Thus, at least a part of the single-sided coating area 231d can extend into the central hole 23b1 or enclose the central hole 23b1.

[0161] With such an arrangement, the inner side of the single-sided coating area 231d is used to connect the buffer member 24 to achieve a support effect, and at the same time, the outer side of the single-sided coating area 231d can be coated with the active material layer 231c. Thus, the active material layer 231c on the single-sided coating area 231d can be fully utilized to improve the energy density of the battery cell 20.

[0162] Please refer to Figure 4 and Figure 6 , in some embodiments, in the winding axial Y direction, the width of the buffer member 24 is less than or equal to the width of the winding body 23b, and the buffer member 24 does not extend outside the central hole 23b1.

[0163] It can be understood that the first pole piece 231, the second pole piece 232, and the separator 233 are wound to form the winding body 23b. Therefore, the width of the winding body 23b is equal to the width of the first pole piece 231 or the width of the second pole piece 232.

[0164] In the winding axial Y direction, the buffer member 24 does not extend outside the central hole 23b1; thus, in the winding axial Y direction, the end of the buffer member 24 can be flush with the end of the winding body 23b, or a gap can be formed between the end of the buffer member 24 and the end of the winding body 23b.

[0165] With such a setting, the buffer member 24 is set not to extend outside the central hole 23b1 in the winding axial Y direction, which can effectively reduce the influence of the buffer member 24 on the recognition of the vision system during the winding operation, and at the same time can also reduce the influence of the buffer member 24 extending outside the central hole 23b1 on the occupied space, thereby reducing the influence on the energy density.

[0166] Please refer to Figure 4 and Figure 6 , in some embodiments, in the winding axial Y direction, the winding body 23b has a width a, and the buffer member 24 has a width b, where 0 ≤ a - b ≤ 2 mm.

[0167] It can be understood that the width a of the winding body 23b can be wider than the width b of the buffer member 24, and the range where the width a of the winding body 23b is wider than the width b of the buffer member 24 does not exceed 2 millimeters (hereinafter, millimeters are replaced by mm). Exemplarily, the width a of the winding body 23b can be, but is not limited to, 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc. wider than the width b of the buffer member 24.

[0168] Or, the width a of the winding body 23b can be the same as the width b of the buffer member 24.

[0169] With such a setting, in the direction perpendicular to the winding direction X, the width of the buffer member 24 can be set to be the same as the width of the winding body 23b to within a range of 2 millimeters narrower than the width of the winding body 23b; if the width of the buffer member 24 is too wide, it may cause an impact on the winding process, and if the width of the buffer member 24 is too narrow, it may cause stress streaks to form on the first pole piece 231 and the second pole piece 232.

[0170] Please refer to Figure 4 and Figure 6 , in some embodiments, 0 ≤ a - b ≤ 1 mm.

[0171] With such a setting, by further limiting the difference between the width of the winding body 23b and the width of the buffer member 24 to be greater than or equal to zero and less than or equal to 1 millimeter, the probability of stress streaks forming on the first pole piece 231 and the second pole piece 232 can be further reduced.

[0172] Please refer to Figure 4 , Figure 9 or Figure 11 , in some embodiments, the buffer member 24 has a compression ratio c, 30% ≤ c ≤ 90%.

[0173] In this embodiment, the compression ratio of the buffer member 24 is defined as greater than or equal to 30% and less than or equal to 90%; exemplarily, the compression ratio of the buffer member 24 can be but is not limited to 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.

[0174] With such a setting, the compression ratio c of the buffer member 24 is defined as greater than or equal to 30% and less than or equal to 90%. Thus, within this range, on the basis of having a better supporting effect, the buffer member 24 has a lower impact on the occupied space.

[0175] Please refer to Figure 4 、 Figure 9 or Figure 11 , in some embodiments, 50% ≤ c ≤ 70%.

[0176] In this embodiment, the compression ratio c of the buffer member 24 is defined as greater than or equal to 50% and less than or equal to 70%; exemplarily, the compression ratio c of the buffer member 24 can be but is not limited to 50%, 52%, 55%, 57%, 60%, 62%, 65%, 67%, 70%, etc.

[0177] With such a setting, the compression ratio c of the buffer member 24 is further defined as greater than or equal to 50% and less than or equal to 70%. Thus, within this range, the supporting effect of the buffer member 24 is further improved, and the impact of the buffer member 24 on the occupied space is further reduced.

[0178] Please refer to Figure 4 、 Figure 9 or Figure 11 , in some embodiments, the buffer member 24 has a thickness d, and 0.5 mm ≤ d ≤ 4 mm.

[0179] In this embodiment, the thickness d of the buffer member 24 is defined as greater than or equal to 0.5 mm and less than or equal to 2 mm; exemplarily, the compression ratio of the buffer member 24 can be but is not limited to 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.7 mm, 1.9 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4 mm, etc.

[0180] With such a setting, the thickness d of the buffer member 24 is defined as greater than or equal to 0.5 mm and less than or equal to 4 mm. Thus, within this range, on the basis of having a better supporting effect, the buffer member 24 has a lower impact on the occupied space.

[0181] Please refer to Figure 4 、 Figure 9 orFigure 11 , 0.5 mm ≤ d ≤ 2 mm.

[0182] With such a setting, the thickness d of the buffer member 24 is further limited to be greater than or equal to 0.5 mm and less than or equal to 2 mm. Thus, within this range, the supporting effect of the buffer member 24 can be further improved, and the influence of the buffer member 24 on the occupied space can be further reduced.

[0183] Please refer to Figure 5 or Figure 6 , in some embodiments, a chamfer structure 241 is formed at at least one end of the buffer member 24 in the winding direction X.

[0184] In this embodiment, the chamfer structure 241 can be formed at one end of the buffer member 24 along the winding direction X, or the chamfer structure 241 can be formed at both opposite ends of the buffer member 24 along the winding direction X.

[0185] Optionally, the chamfer structure 241 includes, but is not limited to, a rounded chamfer structure, an inverted triangular structure, an inverted double triangular structure, an inverted circular arc structure, an inverted semi-circular arc structure, etc.

[0186] With such a setting, by providing the chamfer structure 241 on the buffer member 24, the probability of the end portion of the buffer member 24 generating indentations due to extrusion on the first pole piece 231 and the second pole piece 232 during the cold pressing and shaping process of the winding body 23b can be effectively reduced.

[0187] Please refer to Figure 4 , Figure 10 or Figure 12 , in some embodiments, the buffer member 24 includes any one of a polypropylene buffer member, a polyethylene buffer member, a plexiglass buffer member, a polyester buffer member, and a polycarbonate buffer member.

[0188] With such a setting, using any one of a polypropylene buffer member, a polyethylene buffer member, a plexiglass buffer member, a polyester buffer member, and a polycarbonate buffer member as the buffer member 24 can achieve the supporting effect on the first pole piece 231 and the second pole piece 232.

[0189] Please refer to Figure 4 , Figure 9 , Figure 11 and Figure 15 , in some embodiments, the buffer member 24 is connected to the separator 233.

[0190] It can be understood that an adhesive layer can be coated on the surface of the buffer member 24. Thus, during the process of connecting the buffer member 24 to the first pole piece 231 and / or the second pole piece 232, stacking the first pole piece 231, the separator 233, and the second pole piece 232 in sequence and then winding, the buffer member 24 can be fixedly connected to the separator 233 through the adhesive layer.

[0191] Exemplarily, in some embodiments, the buffer member 24 is fixedly connected to the surface of the first electrode tab 231, and an adhesive layer is provided on the surface of the buffer member 24 facing away from the first electrode tab 231. Thus, the buffer member 24 can also be connected to the separator 233 through the adhesive layer.

[0192] With such a setting, during the winding process of the first electrode tab 231, the second electrode tab 232, and the separator 233, the buffer member 24 can also closely adhere to the separator 233 through the adhesive layer, thereby effectively improving the stability of the buffer member 24 and reducing the probability of misalignment of the buffer member 24 during the winding process.

[0193] Next, the battery cell 20 of the embodiment of the present application will be described in detail according to specific embodiments.

[0194] Please refer to Figures 1 to 8 , in some embodiments, the battery cell 20 includes an electrode assembly 23, and the electrode assembly 23 includes a first electrode tab 231, a second electrode tab 232, and a separator 233 located between the first electrode tab 231 and the second electrode tab 232. In this embodiment, the first electrode tab 231 is a cathode electrode tab, and the second electrode tab 232 is an anode electrode tab. The cathode electrode tab sequentially forms an empty foil area 231a and a coating area 231b along the winding direction X. The coating area 231b is used for coating the active material layer 231c, and a buffer member 24 is connected to the surface of the empty foil area 231a. The electrode tab, the anode electrode tab, and the separator 233 are wound along the winding direction X to form a wound body 23b, so that the empty foil area 231a is located in the central hole 23b1 of the wound body 23b. Among them, the buffer member 24 is connected to the empty foil area 231a, so that the buffer member 24 is also located in the central hole 23b1. Thus, the buffer member 24 can be connected to the empty foil area 231a in the central hole 23b1 and support the cathode electrode tab and the anode electrode tab, thereby reducing the probability of loosening of the inner cathode electrode tab and the anode electrode tab, and being able to support at the corner where the empty foil area 231a forms a corner to increase the corner gap between the cathode electrode tab and the anode electrode tab at the corner, and further reducing the probability of brittle fracture of the cathode electrode tab and the anode electrode tab at the corner.

[0195] Please refer to Figures 11 to 14, in some other embodiments, the battery cell 20 includes an electrode assembly 23. The electrode assembly 23 includes a first electrode tab 231, a second electrode tab 232, and a separator 233 located between the first electrode tab 231 and the second electrode tab 232. The first electrode tab 231, the second electrode tab 232, and the separator 233 are wound along the winding direction X to form a wound body 23b. In this embodiment, the first electrode tab 231 is an anode electrode tab, and the second electrode tab 232 is a cathode electrode tab. The anode electrode tab is sequentially formed with a single-sided coating area 231d and a double-sided coating area 231f along the winding direction X, and the single-sided coating area 231d extends beyond the second electrode tab 232 in the direction opposite to the winding direction X; thus, at least a part of the single-sided coating area 231d is wound to the innermost side of the wound body 23b, and the single-sided coating area 231d can be wound and enclosed to form a central hole 23b1. The buffer member 24 is connected to the inner side of the single-sided coating area 231d, and an active material layer 231c is coated on the outer side of the single-sided coating area 231d; the buffer member 24 can be located within the central hole 23b1 and support the cathode electrode tab and the anode electrode tab, and can support the cathode electrode tab and the anode electrode tab at the corners to increase the corner gap, thereby reducing the probability of brittle fracture of the cathode electrode tab and the anode electrode tab at the corners.

[0196] Please refer to Figures 1 to 4 , in a second aspect, an embodiment of the present application further provides a battery 100, including a box body 10 and the battery cell 20 as described above, and the battery cell 20 is accommodated in the box body 10.

[0197] The battery 100 provided by the embodiment of the present application includes the battery cell 20 as described above. Based on the relatively good reliability of the battery cell 20 as described above, the battery 100 also has relatively good reliability.

[0198] Please refer to Figure 1 and Figure 2 , in a third aspect, an embodiment of the present application further provides an electrical device, including the battery 100 as described above, and the battery 100 is used to provide electrical energy.

[0199] The electrical device provided by the embodiment of the present application is, for example, the vehicle 1000 as described above. The electrical device includes the battery 100 as described above. Based on the relatively good reliability of the battery 100 as described above, the electrical device also has relatively good reliability.

[0200] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, characterized in that: Comprising An electrode assembly, including a first pole piece, a second pole piece, and a separator located between the first pole piece and the second pole piece; the first pole piece, the second pole piece, and the separator are wound along a winding direction to form a wound body, and a central hole is formed along the winding axis at the center of the wound body; the winding direction is perpendicular to the winding axis; And A buffer member, at least partially disposed in the central hole, and the buffer member is connected to the first pole piece and / or the second pole piece.

2. The battery cell according to claim 1, wherein: The first pole piece sequentially forms an empty foil area and a coating area along the winding direction, and the coating area is used for coating an active material layer; In a direction opposite to the winding direction, at least a part of the empty foil area extends beyond the second pole piece, and the buffer member is connected to the empty foil area.

3. The battery cell according to claim 2, characterized in that: The empty foil area is wound along the winding direction to form at least one empty foil bending portion; the buffer member is connected to the empty foil bending portion.

4. The battery cell according to claim 3, wherein: The empty foil area is wound along the winding direction and alternately forms at least one empty foil straight portion and at least one empty foil bending portion; the buffer member is connected to the empty foil straight portion and the empty foil bending portion.

5. The battery cell according to claim 2, wherein: The empty foil area forms at least one empty foil straight portion along the winding direction; the buffer member is connected to the empty foil straight portion.

6. The battery cell according to claim 2, characterized in that: The buffer member includes a first buffer portion, and the first buffer portion is disposed inside the empty foil area.

7. The battery cell according to claim 6, wherein: The buffer member includes a second buffer portion, and the second buffer portion is disposed outside the empty foil area.

8. The battery cell according to claim 7, wherein: The first buffer portion and the second buffer portion are disposed opposite to each other.

9. The battery cell according to any one of claims 2 to 8, characterized in that: In the winding direction, the length o of the buffer member is less than or equal to the length p of the empty foil area.

10. The battery cell according to claim 2, characterized in that: In the winding direction, a gap is formed between the end of the buffer member and the starting end of the coating area.

11. The battery cell according to any one of claims 1 to 8 and 10, characterized in that: The first pole piece is a cathode pole piece, and the second pole piece is an anode pole piece.

12. The battery cell according to any one of claims 1 to 8 and 10, characterized in that: The first pole piece is an anode pole piece, and the second pole piece is a cathode pole piece.

13. The battery cell according to claim 1, wherein: The first pole piece includes a single-sided coating area and a double-sided coating area sequentially arranged along the winding direction, and the buffer member is disposed inside the single-sided coating area; in a direction opposite to the winding direction, at least a part of the single-sided coating area extends beyond the second pole piece.

14. The battery cell according to any one of claims 1 to 8, 10, and 13, characterized in that: In the winding axis direction, the width of the buffer member is less than or equal to the width of the wound body, and the buffer member does not extend outside the central hole.

15. The battery cell according to claim 14, wherein: In the winding axis direction, the wound body has a width a, and the buffer member has a width b, where 0 ≤ a - b ≤ 2 mm.

16. The battery cell according to claim 15, wherein: 0 ≤ a - b ≤ 1 mm.

17. The battery cell according to any one of claims 1 to 8, 10, 13, 15 and 16, characterized in that: The buffer member has a compression ratio c, and 30% ≤ c ≤ 90%.

18. The battery cell according to claim 17, wherein: 50％≤c≤70％。 19. The battery cell according to any one of claims 1 to 8, 10, 13, 15, 16 and 18, characterized in that: The buffer member has a thickness d, and 0.5 mm ≤ d ≤ 4 mm.

20. The battery cell according to claim 19, characterized in that: 0.5 mm ≤ d ≤ 2 mm.

21. The battery cell according to any one of claims 1 to 8, 10, 13, 15, 16, 18 and 20, characterized in that: In the winding direction, at least one end of the buffer member is formed with a chamfer structure.

22. The battery cell according to any one of claims 1 to 8, 10, 13, 15, 16, 18, and 20, characterized in that: The buffer member includes any one of a polypropylene buffer member, a polyethylene buffer member, a plexiglass buffer member, a polyester buffer member, and a polycarbonate buffer member.

23. The battery cell according to any one of claims 1 to 8, 10, 13, 15, 16, 18 and 20, characterized in that: The buffer member is connected to the separator.

24. A battery, characterized in that: Comprising a box body and a battery cell as described in any one of claims 1 to 23, and the battery cell is accommodated in the box body.

25. An electrical device, characterized in that: Comprising a battery as described in claim 24, and the battery is used to provide electric energy.

Images