Battery cell, battery device, and electric device

Abstract

The application relates to a battery monomer, a battery device and a power utilization device. The battery monomer comprises a shell and a winding electrode assembly. The double surfaces of a negative electrode sheet in the winding electrode assembly are provided with a negative electrode active material layer, and the double surfaces of a positive electrode sheet are provided with a positive electrode active material layer. The interval between the bending centers of the two negative electrode bending sections of the innermost negative electrode sheet is X, the end of one negative electrode bending section is a negative electrode winding starting end, the separator winding starting end is located on the inner side of the innermost negative electrode sheet, the length of the separator winding starting end exceeding the negative electrode winding starting end in a first direction is L1, 0 < L1 <= 1.2X, the positive electrode winding starting end is located on the inner side of the innermost negative electrode sheet, the length of the positive electrode winding starting end exceeding the negative electrode winding starting end in the first direction is L2, 0.5X <= L2 <= X, and the first direction is opposite to the winding direction of the innermost negative electrode sheet. In this way, the waste of the separator and the negative electrode is reduced, and the energy density of the battery monomer is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell, a battery device, and an electrical device. Background Technology

[0002] Electrode assemblies are an important part of a battery cell, and typically include wound electrode assemblies and stacked electrode assemblies. Wound electrode assemblies are formed by winding the cathode and anode sheets and the separator after they are fed separately. Therefore, there is waste of separator and anode at the beginning of the winding process, which reduces the energy density of the battery cell. Utility Model Content

[0003] In view of the problem, this application provides a battery cell, battery device and power supply device, where the winding head has the problem of wasted diaphragm and negative electrode, which reduces the energy density of the battery cell.

[0004] In a first aspect, this application provides a battery cell, comprising:

[0005] The outer shell has a receiving cavity;

[0006] A wound electrode assembly is disposed in a receiving cavity. The wound electrode assembly includes a negative electrode sheet, a positive electrode sheet, and a separator. Both sides of the negative electrode sheet are coated with a negative electrode active material, both sides of the positive electrode sheet are coated with a positive electrode active material, and the separator is disposed between the negative electrode sheet and the positive electrode sheet.

[0007] Among them, the negative electrode sheet has a negative electrode winding start end, the positive electrode sheet has a positive electrode winding start end, and the diaphragm has a diaphragm winding start end;

[0008] The innermost negative electrode sheet is formed by winding the negative electrode sheet once from the starting end of the negative electrode winding. The innermost negative electrode sheet has two opposite negative electrode bending sections, and the distance between the bending centers of the two negative electrode bending sections is X. The end of one of the negative electrode bending sections is the starting end of the negative electrode winding.

[0009] The starting end of the diaphragm winding is located inside the innermost negative electrode sheet, and the length of the starting end of the diaphragm winding beyond the starting end of the negative electrode winding along the first direction is L1, where 0 < L1 ≤ 1.2X;

[0010] The positive electrode winding start end is located inside the innermost negative electrode plate, and the positive electrode winding start end extends beyond the negative electrode winding start end by a length L2 along the first direction, where 0.5X≤L2≤X;

[0011] The first direction is opposite to the direction of the diaphragm winding start end along the winding direction beyond the negative electrode winding start end.

[0012] The aforementioned battery cell, by setting the distance between the bending centers of the two negative electrode bending sections as X, limits the length L1 of the separator winding start end extending beyond the negative electrode winding start end to 0 < L1 ≤ 1.2X, reducing the excess separator occupying the internal space of the wound electrode assembly and reducing separator waste. At the same time, the length L2 of the positive electrode winding start end extending beyond the negative electrode winding start end is limited to the range of 0.5X ≤ L2 ≤ X, allowing the positive electrode to cover the innermost circle of negative electrode active material area that was originally not effectively utilized, eliminating the "ineffective negative electrode surface" in the original structure, and allowing this part of the negative electrode active material to participate in the electrochemical reaction normally. This not only makes full use of the internal space of the wound electrode assembly, but also increases the proportion of active material inside the battery cell, thereby effectively improving the energy density of the battery cell.

[0013] In one embodiment, 0 < L1 ≤ 0.3X or X ≤ L1 ≤ 1.2X.

[0014] When the length L1 by which the separator winding start end extends beyond the negative electrode winding start end along the first direction is set to 0 < L1 ≤ 0.3X, the number of separator layers in the innermost negative electrode sheet can be reduced, further reducing separator waste. Additionally, it frees up space in the innermost negative electrode sheet, making the wound electrode assembly more compact after the winding and shaping process, reducing the thickness of the wound electrode assembly, and consequently reducing the thickness of the battery cell. When the length L1 by which the separator winding start end extends beyond the negative electrode winding start end along the first direction is set to X ≤ L1 ≤ 1.2X, although the number of separator layers between the positive electrode sheet and the innermost negative electrode sheet in the innermost negative electrode sheet is still multiple, the number of separator layers is reduced compared to traditional winding processes. Furthermore, because the length by which the separator winding start end extends beyond the negative electrode winding start end is longer, it can compensate for tolerances generated during winding and isolate the negative electrode winding start end from the positive electrode winding start end, thereby reducing the possibility of short circuits between them.

[0015] In one embodiment, when X≤L1≤1.2X, one of the two negative electrode bending segments has a negative electrode winding start end, and the portion of the diaphragm winding start end extending beyond the negative electrode winding start end along a first direction has a diaphragm bending segment, the diaphragm bending segment being located inside the other negative electrode bending segment away from the negative electrode winding start end, and the diaphragm bending segment having a negative electrode winding start end.

[0016] When X≤L1≤1.2X, the length of the diaphragm winding start end extending beyond the negative electrode winding start end is relatively long. In this case, the portion of the diaphragm winding start end extending beyond the negative electrode winding start end along the first direction is provided with a diaphragm bending section. This not only reduces the number of diaphragm layers, compensates for the tolerances generated during winding, and reduces the short circuit between the negative electrode winding start end and the positive electrode winding start end, but also meets the requirements of the process winding.

[0017] In one embodiment, the innermost diaphragm is formed by winding the diaphragm once from the starting end of the diaphragm winding, and the circumference of the innermost diaphragm is C1, where 0.01C1≤L1≤0.75C1.

[0018] L1 represents the length of the separator winding start end extending beyond the negative electrode winding start end along the first direction. When the circumference of the innermost separator is C1, and the constraint is 0.01C1≤L1≤0.75C1, it is equivalent to the negative electrode winding start end entering the winding process when the separator has been wound for 0.01 to 0.75 turns. This indicates that the negative electrode winding start end has already begun the winding process simultaneously when the separator winding start end has just entered the winding process and before the first turn of winding is completed. Through this closely linked timing control method, the unwound length of the separator in the absence of electrode cooperation is effectively shortened, thereby further reducing the redundant use and unnecessary waste of separator material in the initial stage of winding. At the same time, because the negative electrode can participate in winding earlier, the entire winding process of the wound electrode assembly can be promoted more compactly and efficiently, significantly accelerating the overall cycle time of the winding process, not only reducing separator waste but also improving the production efficiency in the battery production process.

[0019] In one embodiment, 0.01C1≤L1≤0.2C1 or 0.5C1≤L1≤0.75C1.

[0020] When the length L1 of the separator winding start end extending beyond the negative electrode winding start end in the first direction is set to 0.01C1≤L1≤0.2C1, this indicates that the negative electrode winding start end has already started the winding process simultaneously as the separator winding start end just enters the winding process. This tightly integrated timing control method further shortens the unwound length of the separator without electrode contact. Compared to the material used before the negative electrode is wound in traditional winding processes, this application reduces separator material by more than 80% and further improves production efficiency in the battery manufacturing process.

[0021] When the length L1 of the separator winding start end extending beyond the negative electrode winding start end in the first direction is set to 0.5C1≤L1≤0.75C1, this indicates that the negative electrode winding start end has already begun the winding process simultaneously when the separator winding start end enters the winding process to half a turn but before the first turn is completed. This tightly integrated timing control method effectively shortens the unwound length of the separator in the absence of electrode contact. Compared to the material used before the negative electrode is wound in traditional winding processes, this application reduces separator material by more than 50% and further improves production efficiency in the battery manufacturing process.

[0022] In one embodiment, the circumference of the innermost negative electrode sheet along the winding direction is C2, and a first point is defined on the circumference. The first point is aligned with the starting end of the positive electrode winding, and the length from the starting point of the circumference along the winding direction to the first point is L3, where 0.5C2≤L3≤C2.

[0023] When the circumference of the innermost negative electrode sheet is C2, and the length L3 from the starting point of the circumference winding direction to the first point on the circumference aligned with the starting end of the positive electrode winding is limited to 0.5C2≤L3≤C2, this indicates that the starting end of the positive electrode sheet winding has already begun the winding process simultaneously when the starting end of the negative electrode winding enters the winding process to half a turn, but before the first turn is completed or just after the first turn is completed. This tightly integrated timing control method allows the starting end of the positive electrode winding to enter the innermost negative electrode sheet, enabling the positive electrode to cover the previously unused negative electrode active material area, eliminating the "ineffective negative electrode surface" in the original structure. This fully utilizes the internal space of the wound electrode assembly while effectively improving the energy density of the battery cell.

[0024] In one embodiment, the negative electrode sheet has a negative electrode winding end, and the positive electrode sheet has a positive electrode winding end.

[0025] Along the winding direction, the end of the negative electrode winding extends beyond the end of the positive electrode winding.

[0026] In this way, the outermost negative electrode can cover the end of the positive electrode winding, which can reduce the risk of lithium dendrite precipitation and internal short circuit caused by the exposure of the positive electrode edge.

[0027] In one embodiment, the diaphragm has a diaphragm winding end that extends beyond the negative electrode winding end along the winding direction.

[0028] In this way, the outermost separator can cover the end of the negative electrode winding, which can prevent the negative electrode sheet from directly contacting the side wall of the casing, reducing the probability of side reactions between the negative electrode active material and the casing. At the same time, it can also play a good role in insulation and protection, further improving the overall safety performance and cycle life of the battery cell.

[0029] In a second aspect, a battery device is provided, comprising the battery cell in any of the above embodiments.

[0030] Thirdly, an electrical device is also provided, including the battery in any of the above embodiments.

[0031] 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

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0033] Figure 1 This is a structural schematic diagram of a vehicle according to one or more embodiments.

[0034] Figure 2 This is an exploded structural diagram of a battery according to one or more embodiments.

[0035] Figure 3 This is an exploded structural diagram of a battery cell according to one or more embodiments.

[0036] Figure 4 This is a cross-sectional schematic diagram of a wound electrode assembly for a battery cell according to one or more embodiments.

[0037] Figure 5 for Figure 4 A schematic cross-sectional view of the central portion of the wound electrode assembly shown.

[0038] Figure 6 for Figure 5 A cross-sectional schematic diagram (1) showing the dimensions of the central portion of the wound electrode assembly.

[0039] Figure 7 for Figure 5 A cross-sectional schematic diagram (2) showing the marked dimensions of the central portion of the wound electrode assembly.

[0040] Figure 8 This is a cross-sectional schematic diagram of a wound electrode assembly for a battery cell according to one or more other embodiments.

[0041] Figure 9 for Figure 8 A schematic cross-sectional view of the central portion of the wound electrode assembly shown.

[0042] The reference numerals in the detailed embodiments are as follows:

[0043] 1000, Vehicle; 100, Battery assembly; 10, Housing; 11, First part; 12, Second part; 20, Battery cell; 21, End cap; 211, Terminal post; 22, Housing; 23, Winded electrode assembly; 231, Tab; 232, Negative electrode; 2321, Negative electrode winding start end; 2322, Negative electrode bending section; 2323, Negative electrode winding end; 233, Positive electrode; 2331, Positive electrode winding start end; 2332, Positive electrode winding end; 234, Separator; 2341, Separator winding start end; 2342, First separator; 2343, Second separator; 2344, Separator bending section; 2345, Separator winding end; 24, Outer shell; 241, Receiving cavity; 200, Controller; 300, Motor. Detailed Implementation

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between associated objects, indicating that three relationships can exist. For example, 1 and / or 2 can represent: 1 existing alone, 1 and 2 existing simultaneously, and 2 existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following associated objects have an "or" relationship.

[0049] 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).

[0050] 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.

[0051] 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.

[0052] Currently, in the winding process of wound electrode assemblies, the commonly used method is to feed the negative electrode sheet, positive electrode sheet and separator into the winding equipment separately, and then wind them synchronously to form a complete wound electrode assembly.

[0053] However, in this process, to ensure the structural stability and safety of the wound electrode assembly at the beginning of the winding stage, an additional 1 to 3 turns of separator are usually wound at the winding head. While this design helps to prevent electrode misalignment or short circuit risks to some extent, these extra wound separators do not participate in the electrochemical reaction and are inactive materials, thus occupying valuable internal space and significantly reducing the overall volume utilization of the wound electrode assembly, thereby having a significant negative impact on the energy density of the battery cell.

[0054] Meanwhile, in the innermost region of the wound electrode assembly, there is a situation where negative electrode sheets are placed face-to-face, resulting in a portion of the negative electrode sheet surface not being effectively covered by the positive electrode. This prevents the negative electrode active material in this area from fully participating in the charge and discharge reaction, forming an "ineffective negative electrode surface." This unused negative electrode also wastes the effective space and material resources inside the wound electrode assembly, further weakening the energy density performance of the battery cell.

[0055] To alleviate the waste of separator and negative electrode at the winding head of the wound electrode assembly, thus reducing the energy density of the battery cell, this application designs a battery cell including a shell and a wound electrode assembly. The shell has a receiving cavity; the wound electrode assembly is disposed in the receiving cavity, and the wound electrode assembly includes a negative electrode sheet, a positive electrode sheet, and a separator. The negative electrode sheet includes a negative current collector and a negative active material layer, with the negative active material layer disposed on two opposite sides of the negative current collector. The positive electrode sheet includes a positive current collector and a positive active material layer, with the positive active material layer disposed on two opposite sides of the positive current collector. The separator is disposed between the negative electrode sheet and the positive electrode sheet. The negative electrode sheet has a negative winding start end, the positive electrode sheet has a positive winding start end, and the separator has a separator winding start end. One rotation of the negative electrode sheet from the negative winding start end constitutes one revolution. The innermost negative electrode sheet has two opposing negative electrode bending sections, with a distance of X between the bending centers of the two negative electrode bending sections. The end of one of the negative electrode bending sections is the negative electrode winding start end. The diaphragm winding start end is located inside the innermost negative electrode sheet, and the length of the diaphragm winding start end extending beyond the negative electrode winding start end along the first direction is L1, where 0 < L1 ≤ 1.2X. The positive electrode winding start end is located inside the innermost negative electrode sheet, and the length of the positive electrode winding start end extending beyond the negative electrode winding start end along the first direction is L2, where 0.5X ≤ L2 ≤ X. The first direction is opposite to the winding direction of the innermost negative electrode sheet.

[0056] Thus, by setting the distance between the bending centers of the two negative electrode bending sections as X, and limiting the length L1 of the separator winding start end beyond the negative electrode winding start end to 0 < L1 ≤ 1.2X, the excess separator occupying the internal space of the wound electrode assembly is reduced, thus reducing separator waste. At the same time, the length L2 of the positive electrode winding start end beyond the negative electrode winding start end is limited to the range of 0.5X ≤ L2 ≤ X, allowing the positive electrode to cover the innermost circle of negative electrode active material area that was originally not effectively utilized. This eliminates the "ineffective negative electrode surface" in the original structure, allowing this part of the negative electrode active material to participate in the electrochemical reaction normally. This not only makes full use of the internal space of the wound electrode assembly, but also increases the proportion of active material inside the battery cell, thereby effectively improving the energy density of the battery cell.

[0057] The battery cell of this application is used in a battery device to alleviate the problem of waste of the separator and negative electrode at the head of the wound electrode assembly, thereby reducing the energy density of the battery cell.

[0058] The battery devices disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft.

[0059] 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.

[0060] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0061] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is provided inside the vehicle 1000, and the battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during starting, navigation, and driving.

[0062] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0063] Please refer to Figure 2 , Figure 2This is an exploded view of a battery device 100 provided in some embodiments of this application. The battery device 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a space for accommodating the battery cell 20, and the housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, jointly defining a space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 jointly define the space; alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0064] In the battery device 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel connections. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, parallel, or in a mixed configuration to form battery modules, and then these battery modules are connected in series, parallel, or in a mixed configuration to form a whole, which is also housed within the housing 10. The battery device 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0065] 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 is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0066] Please refer to Figure 3 , Figure 3 This is an exploded structural diagram of a battery cell 20 provided in some embodiments of this application. The battery cell 20 refers to the smallest unit that makes up a battery. Figure 3 The battery cell 20 includes an end cap 21, a housing 22, a wound electrode assembly 23, and other functional components.

[0067] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure and impact, allowing battery cell 20 to have higher structural strength and improved safety performance. Functional components such as terminals 211 can be provided on end cap 21. Terminals 211 can be used to electrically connect to wound electrode assembly 23 for outputting or inputting electrical energy to battery cell 20. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 20 reaches a threshold. The material of end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0068] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the wound 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 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 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 22, the end cap 21 closes 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 wound electrode assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special limitations on this.

[0069] The wound electrode assembly 23 is the component in the battery cell 20 where the electrochemical reaction occurs. The housing 22 may contain one or more wound electrode assemblies 23. The wound electrode assembly 23 mainly consists of positive and negative electrode materials, a separator, and a current collector. Specifically, positive electrode material is coated on the battery output electrode connector to form a positive electrode sheet 233, and negative electrode material is coated on the battery output electrode connector to form a negative electrode sheet 232. The positive and negative electrode sheets 233 and 232 are wound together, and a separator is disposed between the positive and negative electrode sheets 233 and 232, thus forming the wound electrode assembly 23. The portions of the positive and negative electrode sheets 233 and 232 containing active material constitute the main body of the wound electrode assembly, while the portions of the positive and negative electrode sheets 233 and 232 without active material each constitute a tab 231. The positive and negative tabs 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, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tab 231 connects to the terminal 211 to form a current circuit.

[0070] See appendix Figures 4-9 This application provides a battery cell 20, which includes a housing 24 and a wound electrode assembly 23. The housing 24 has a receiving cavity 241, and the wound electrode assembly 23 is disposed within the receiving cavity 241. The wound electrode assembly 23 includes a negative electrode 232, a positive electrode 233, and a separator 234. The negative electrode 232 includes a negative current collector and a negative active material layer, which are disposed on two opposite surfaces of the negative current collector. The positive electrode 233 includes a positive current collector and a positive active material layer, which are disposed on two opposite surfaces of the positive current collector. The separator 234 is disposed between the negative electrode 232 and the positive electrode 233. The negative electrode 232 has a negative winding start end 2321, the positive electrode 233 has a positive winding start end 2331, and the separator 234 has a separator winding start end 2341. The negative electrode 232 is wound around the negative electrode starting end 2321 to form the innermost negative electrode. The innermost negative electrode has two opposing negative electrode bending sections 2322, and the distance between the bending centers of the two negative electrode bending sections 2322 is X. The end of one of the negative electrode bending sections 2322 is the negative electrode winding starting end 2321. The starting end of the diaphragm 234 is located inside the innermost negative electrode 232, and the length of the diaphragm winding starting end 2341 extending beyond the negative electrode winding starting end 2321 along the first direction is L1, where 0 < L1 ≤ 1.2X. The starting end of the positive electrode winding 2331 is located inside the innermost negative electrode 232, and the length of the positive electrode winding starting end 2331 extending beyond the negative electrode winding starting end 2321 along the first direction is L2, where 0.5X ≤ L2 ≤ X. The first direction is opposite to the winding direction of the innermost negative electrode.

[0071] The outer casing 24 may include the end cap 21 and the housing 22 in the above embodiments, with the end cap 21 and the housing 22 forming a receiving cavity 241 together.

[0072] The term "positive electrode active material layer located on two opposite sides of the positive electrode current collector" means that the positive electrode current collector has a positive electrode active material layer on both opposite sides along its thickness direction. Similarly, the term "negative electrode active material layer located on two opposite sides of the negative electrode current collector" means that the negative electrode current collector has a negative electrode active material layer on both opposite sides along its thickness direction. Specific materials for the positive electrode active material can include graphite, lithium titanate, and silicon oxide, while specific materials for the negative electrode active material can include lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, and ternary materials.

[0073] The function of the diaphragm 234 is to separate the negative electrode 232 and the positive electrode 233, and to provide an ion transport channel between them. Specifically, the diaphragm 234 may include a first diaphragm 2342 and a second diaphragm 2343, with the negative electrode 232 disposed between the first diaphragm 2342 and the second diaphragm 2343, and the positive electrode 233 also disposed between the first diaphragm 2342 and the second diaphragm 2343.

[0074] The negative electrode winding start end 2321 of the negative electrode sheet 232 refers to the starting point of the winding of the negative electrode sheet 232 when it is wound to form the wound electrode assembly 23. After winding, the negative electrode winding start end 2321 is located at the innermost side of the wound electrode assembly 23 relative to the other parts of the negative electrode sheet 232. Similarly, the positive electrode winding start end 2331 of the positive electrode sheet 233 and the diaphragm winding start end 2341 of the diaphragm 234 are defined in the same way.

[0075] The innermost negative electrode sheet 232, which is the portion of the negative electrode sheet 232 that completes one full circle around the central axis of the wound electrode assembly 23 from the starting point 2321, is understood to be positioned flush with but spaced from the starting point 2321 along the thickness direction of the wound electrode assembly 23. This application schematically uses... Figure 6 The double-arrow curve S1 represents the innermost negative electrode plate.

[0076] The two negative electrode bending segments 2322 of the innermost negative electrode sheet refer to the turning positions of the negative electrode sheet 232 during winding. The negative electrode bending segments 2322 are roughly arc-shaped, so the bending center of the negative electrode bending segment 2322 can be equated to the center of the arc. However, when the negative electrode bending segment 2322 is not arc-shaped, this bending center is the core point or axis around which the turning occurs. The distance X between the bending centers of the two negative electrode bending segments 2322 is already specified in the original text. Figure 6The diagram illustrates this. The end of one of the negative electrode bending sections 2322, designated as the negative electrode winding start end 2321, means that the negative electrode winding start end 2321 can serve as the end point of the bending section, as shown below. Figure 5 As shown, the end point of the bend on the left is the negative electrode winding start point 2321.

[0077] The phrase "the starting end of the separator 234 is located inside the innermost negative electrode sheet" means that the starting end of the separator 234 is inside the loop formed by the innermost negative electrode sheet. Similarly, the phrase "the starting end of the positive electrode winding 2331 is located inside the innermost negative electrode sheet" means that the starting end of the positive electrode winding 2331 is inside the loop formed by the innermost negative electrode sheet.

[0078] The first direction is opposite to the winding direction of the innermost negative electrode sheet, specifically it can be... Figure 5 As shown in the horizontal rightward direction, when the portion of the diaphragm winding start end 2341 extending beyond the negative electrode winding start end 2321 along the winding direction has a bend, for example... Figure 8 As shown, the first direction can specifically be... Figure 8 The direction shown is horizontal, turning right and then downward.

[0079] Thus, by setting the distance between the bending centers of the two negative electrode bending sections 2322 to X, and limiting the length L1 of the separator winding start end 2341 extending beyond the negative electrode winding start end 2321 to 0 < L1 ≤ 1.2X, the excess separator 234 occupying the internal space of the wound electrode assembly 23 is reduced, thus reducing the waste of separator 234. At the same time, the length L2 of the positive electrode winding start end 2331 extending beyond the negative electrode winding start end 2321 is limited to the range of 0.5X ≤ L2 ≤ X, so that the positive electrode can cover the innermost circle of negative electrode active material area that was originally not effectively utilized, eliminating the "ineffective negative electrode surface" in the original structure, allowing this part of the negative electrode active material to participate in the electrochemical reaction normally. This not only makes full use of the internal space of the wound electrode assembly 23, but also increases the proportion of active material inside the battery cell 20, thereby effectively improving the energy density of the battery cell 20.

[0080] According to some embodiments of this application, 0 < L1 ≤ 0.3X or X ≤ L1 ≤ 1.2X.

[0081] See Figures 4-7 When the length L1 of the diaphragm winding start end 2341 extending beyond the negative electrode winding start end 2321 along the first direction is 0 < L1 ≤ 0.3X, the length of the diaphragm winding start end 2341 extending beyond the negative electrode winding start end 2321 is relatively short. Figure 4 For example, it can be seen that the separator 234 between the positive electrode 233 in the innermost negative electrode and the innermost negative electrode is only one layer.

[0082] This reduces the number of separator layers 234 located within the innermost negative electrode sheet, further reducing separator waste. Additionally, it frees up space within the innermost negative electrode sheet, allowing the wound electrode assembly 23 to be more compact after the winding and shaping process, reducing the thickness of the wound electrode assembly 23 and consequently reducing the thickness of the battery cell 20.

[0083] See Figure 8 and Figure 9 When the length L1 by which the diaphragm winding start end 2341 extends beyond the negative electrode winding start end 2321 along the first direction is set to X≤L1≤1.2X, the length by which the diaphragm winding start end 2341 extends beyond the negative electrode winding start end 2321 is relatively long. Figure 9 For example, it can be seen that the number of layers of the separator 234 between the positive electrode 233 in the innermost negative electrode and the innermost negative electrode is three. It should also be noted that the length L1 of the separator winding start end 2341 extending beyond the negative electrode winding start end 2321 along the first direction includes the separator length at the corner.

[0084] Although the number of layers of the separator 234 between the positive electrode 233 in the innermost negative electrode and the innermost negative electrode is still multiple, the number of layers of the separator 234 has been reduced compared to the traditional winding process. Furthermore, since the length of the separator winding start end 2341 that exceeds the negative electrode winding start end 2321 is relatively long, it can compensate for the tolerance generated during winding and isolate the negative electrode winding start end 2321 from the positive electrode winding start end 2331, thereby reducing the possibility of short circuit between the two.

[0085] See Figures 4-7 Specifically, when 0 < L1 ≤ 0.3X, one of the two negative electrode bending segments 2322 has a negative electrode winding start end 2321.

[0086] As described above, when 0 < L1 ≤ 0.3X, the length of the diaphragm winding start end 2341 extending beyond the negative electrode winding start end 2321 is relatively short. In this case, setting the negative electrode winding start end 2321 as the end of the negative electrode bending section 2322 means that the length of the end of the diaphragm winding start end 2341 extending beyond the negative electrode bending section 2322 is relatively short. This not only reduces the occupancy rate of the diaphragm 234 in the innermost negative electrode sheet and reduces the number of diaphragm 234 layers in the innermost negative electrode sheet, but also meets the requirements of the process winding.

[0087] The requirement of meeting the winding process here refers to the fact that when the diaphragm 234 of the wound electrode assembly 23 is wound, the starting end 2341 of the diaphragm winding needs to be located on one side of the joint between the two half-shafts of the winding needle. This way, when the wound part is pulled out of the winding needle after winding, the clamping part can clamp both sides of the joint between the two half-shafts to fix the wound part, thereby preventing it from unraveling and improving the reliability of subsequent shaping of the wound part to form the wound electrode assembly 23. When both the starting end 2321 of the negative electrode winding and the starting end 2341 of the diaphragm winding are close to one side of the joint between the two half-shafts, it is equivalent to clamping the ends of the negative electrode sheet 232 and the diaphragm 234, thus meeting the requirements of the winding process.

[0088] See Figure 8 and Figure 9 Specifically, when X≤L1≤1.2X, one of the two negative electrode bending sections 2322 has a negative electrode winding start end 2321, and the portion of the diaphragm winding start end 2341 extending beyond the negative electrode winding start end 2321 in the first direction has a diaphragm bending section 2344. The diaphragm bending section 2344 is located inside the other negative electrode bending section 2322 away from the negative electrode winding start end 2321, and the diaphragm bending section 2344 has the negative electrode winding start end 2321.

[0089] As described above, when X≤L1≤1.2X, the length of the diaphragm winding start end 2341 extending beyond the negative electrode winding start end 2321 is relatively long. In this case, the portion of the diaphragm winding start end 2341 extending beyond the negative electrode winding start end 2321 along the first direction is provided with a diaphragm bending section 2344. This not only reduces the number of layers of the diaphragm 234, compensates for the tolerances generated during winding, and reduces the short circuit between the negative electrode winding start end 2321 and the positive electrode winding start end 2331, but also meets the requirements of the process winding.

[0090] As described above, meeting the requirements of the winding process is to reduce the risk of the diaphragm 234 spreading out inside the winding when the winding needle is pulled out if the diaphragm 2344 does not have a diaphragm bending section 2344 after the diaphragm winding start end 2341 exceeds the negative electrode winding start end 2321 by a certain length. Therefore, when the diaphragm bending section 2344 is close to the side of the joint of the two half shafts, it is equivalent to clamping the diaphragm bending section 2344. At this time, the requirements of the winding process are met.

[0091] See Figures 4-9 According to some embodiments of this application, the diaphragm 234 is wound around the starting end 2341 of the diaphragm winding to form the innermost diaphragm, and the circumference of the innermost diaphragm is C1, where 0.01C1≤L1≤0.75C1.

[0092] The innermost ring of the diaphragm 234, which is the portion of the diaphragm 234 that completes one full circle around the central axis of the wound electrode assembly 23 from the starting end 2341, is understood to be positioned flush with but spaced apart from the starting end 2341 along the thickness direction of the wound electrode assembly 23. This application schematically uses... Figure 6 The double-arrow curve S2 represents the innermost diaphragm.

[0093] L1 is the length of the diaphragm winding start end 2341 extending beyond the negative electrode winding start end 2321 in the first direction. When the circumference of the innermost diaphragm is C1, and the condition is limited to 0.01C1≤L1≤0.75C1, it is equivalent to the negative electrode winding start end 2321 being wound into the diaphragm 234 after 0.01 to 0.75 turns. This indicates that the negative electrode winding start end has already started the winding process simultaneously when the diaphragm winding start end 2341 has just entered the winding process and has not yet completed the first turn of winding. This tightly integrated timing control method effectively shortens the unwound length of the separator 234 without electrode support, thereby further reducing redundant use and unnecessary waste of the separator 234 material at the beginning of winding. At the same time, since the negative electrode can participate in winding earlier, the entire winding process of the wound electrode assembly 23 can be promoted more compactly and efficiently, significantly accelerating the overall cycle time of the winding process. This not only reduces the waste of the separator 234 but also improves the production efficiency in the battery production process.

[0094] Specifically, 0.01C1≤L1≤0.2C1 or 0.5C1≤L1≤0.75C1.

[0095] See Figures 4-7 When the length L1 of the separator winding start end 2341 extending beyond the negative electrode winding start end 2321 in the first direction is set to 0.01C1≤L1≤0.2C1, this indicates that the negative electrode winding start end has already started the winding process simultaneously when the separator winding start end 2341 just enters the winding process. Through this closely linked timing control method, the unwound length of the separator 234 without electrode contact is further shortened. Compared to the material used before the negative electrode sheet 232 is wound in the traditional winding process, this application reduces the separator 234 material by more than 80% and further improves the production efficiency in the battery manufacturing process.

[0096] See Figure 8 and Figure 9When the length L1 of the separator winding start end 2341 extending beyond the negative electrode winding start end 2321 in the first direction is set to 0.5C1≤L1≤0.75C1, this indicates that when the separator winding start end 2341 enters the winding process to half a turn but before the first turn is completed, the negative electrode winding start end has already simultaneously entered the winding process. This tightly integrated timing control method effectively shortens the unwound length of the separator 234 without electrode contact. Compared to the material used before the negative electrode 232 is wound in the traditional winding process, this application reduces the separator 234 material by more than 50% and further improves the production efficiency in the battery manufacturing process.

[0097] See Figures 4-9 According to some embodiments of this application, the circumference of the innermost negative electrode sheet along the winding direction is C2, and a first point O1 is defined on the circumference. The first point O1 is aligned with the positive electrode winding start end 2331. The length from the starting point O2 of the circumference to the first point along the winding direction is L3, and 0.5C2≤L3≤C2.

[0098] When the circumference of the innermost negative electrode sheet is C2, and the length L3 from the starting point O2 of the circumference along the winding direction to the first point O1 aligned with the starting end 2331 of the positive electrode winding is limited to 0.5C2≤L3≤C2, this indicates that when the starting end 2321 of the negative electrode winding enters the winding process to half a turn of winding, but has not yet completed the first turn of winding or has just completed the first turn of winding, the starting end of the positive electrode sheet 233 has already entered the winding process simultaneously. Through this closely linked timing control method, the starting end 2331 of the positive electrode winding can enter the innermost negative electrode sheet, allowing the positive electrode to cover the innermost negative electrode active material area that was originally not effectively utilized, eliminating the "ineffective negative electrode surface" in the original structure, making full use of the internal space of the wound electrode assembly 23, and effectively improving the energy density of the battery cell 20.

[0099] Please see Figure 4 According to some embodiments of this application, the negative electrode 232 has a negative electrode winding end 2323, and the positive electrode 233 has a positive electrode winding end 2332. Along the winding direction, the negative electrode winding end 2323 extends beyond the positive electrode winding end 2332.

[0100] In this way, the outermost negative electrode 232 can cover the positive electrode winding end 2332, which can reduce the risk of lithium dendrite precipitation and internal short circuit caused by the exposure of the positive electrode edge 233.

[0101] Furthermore, the diaphragm 234 has a diaphragm winding end 2345, which extends beyond the negative electrode winding end 2323 along the winding direction.

[0102] In this way, the outermost separator 234 can cover the negative electrode winding end 2323, which can prevent the negative electrode sheet 232 from directly contacting the side wall of the outer casing 24, reducing the probability of side reactions between the negative electrode active material and the outer casing 24, and at the same time playing a good insulating protection role, further improving the overall safety performance and cycle life of the battery cell 20.

[0103] According to some embodiments of this application, a battery device 100 is provided, including the battery cell 20 in any of the above embodiments.

[0104] In this embodiment, the battery device 100 sets the distance between the bending centers of the two negative electrode bending sections 2322 to X, and limits the length L1 of the separator winding start end 2341 extending beyond the negative electrode winding start end 2321 to 0 < L1 ≤ 1.2X. This reduces the amount of excess separator 234 occupying the internal space of the wound electrode assembly 23 and reduces the waste of separator 234. At the same time, the length L2 of the positive electrode winding start end 2331 extending beyond the negative electrode winding start end 2321 is limited to the range of 0.5X ≤ L2 ≤ X, so that the positive electrode can cover the innermost circle of negative electrode active material area that was originally not effectively utilized. This eliminates the "ineffective negative electrode surface" in the original structure, allowing this part of the negative electrode active material to participate normally in the electrochemical reaction. This not only makes full use of the internal space of the wound electrode assembly 23, but also increases the proportion of active material inside the battery cell 20, thereby effectively improving the energy density of the battery cell 20.

[0105] In addition, this application also provides an electrical device, including the battery device 100 in any of the above embodiments.

[0106] In this embodiment, the electrical device sets the distance between the bending centers of the two negative electrode bending sections 2322 to X, and limits the length L1 of the separator winding start end 2341 extending beyond the negative electrode winding start end 2321 to 0 < L1 ≤ 1.2X. This reduces the amount of excess separator 234 occupying the internal space of the wound electrode assembly 23, thus reducing the waste of separator 234. At the same time, the length L2 of the positive electrode winding start end 2331 extending beyond the negative electrode winding start end 2321 is limited to the range of 0.5X ≤ L2 ≤ X, so that the positive electrode can cover the innermost circle of negative electrode active material area that was originally not effectively utilized. This eliminates the "ineffective negative electrode surface" in the original structure, allowing this part of the negative electrode active material to participate normally in the electrochemical reaction. This not only makes full use of the internal space of the wound electrode assembly 23, but also increases the proportion of active material inside the battery cell 20, thereby effectively improving the energy density of the battery cell 20.

[0107] 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 in that, include: The outer shell has a receiving cavity; A wound electrode assembly is disposed within the receiving cavity. The wound electrode assembly includes a negative electrode sheet, a positive electrode sheet, and a separator. The negative electrode sheet includes a negative current collector and a negative active material layer, with the negative active material layer disposed on two opposite surfaces of the negative current collector. The positive electrode sheet includes a positive current collector and a positive active material layer, with the positive active material layer disposed on two opposite surfaces of the positive current collector. The separator is disposed between the negative electrode sheet and the positive electrode sheet. The negative electrode sheet has a negative electrode winding start end, the positive electrode sheet has a positive electrode winding start end, and the diaphragm has a diaphragm winding start end. The negative electrode sheet is wound around the negative electrode starting end to form the innermost negative electrode sheet; the innermost negative electrode sheet has two opposite negative electrode bending sections, the distance between the bending centers of the two negative electrode bending sections is X, and the end of one of the negative electrode bending sections is the negative electrode winding starting end. The starting end of the diaphragm winding is located inside the innermost negative electrode sheet, and the length of the starting end of the diaphragm winding beyond the starting end of the negative electrode winding along the first direction is L1, where 0 < L1 ≤ 1.2X; The positive electrode winding start end is located inside the innermost negative electrode sheet, and the positive electrode winding start end extends beyond the negative electrode winding start end along the first direction by a length L2, where 0.5X≤L2≤X; The first direction is opposite to the winding direction of the innermost negative electrode sheet.

2. The battery cell according to claim 1, characterized in that, 0 < L1 ≤ 0.3X or X ≤ L1 ≤ 1.2X.

3. The battery cell according to claim 2, characterized in that, When X≤L1≤1.2X, one of the two negative electrode bending segments has the negative electrode winding start end, the portion of the diaphragm winding start end extending beyond the negative electrode winding start end along the first direction has a diaphragm bending segment, the diaphragm bending segment is located inside the other negative electrode bending segment away from the negative electrode winding start end, and the diaphragm bending segment has the negative electrode winding start end.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The innermost diaphragm is formed by winding the diaphragm once from the starting end of the diaphragm winding. The circumference of the innermost diaphragm is C1, where 0.01C1≤L1≤0.75C1.

5. The battery cell according to claim 4, characterized in that, 0.01C1≤L1≤0.2C1 or 0.5C1≤L1≤0.75C1.

6. The battery cell according to any one of claims 1 to 3, characterized in that, The circumference of the innermost negative electrode sheet along the winding direction is C2. A first point is defined on the circumference, which is aligned with the starting end of the positive electrode winding. The length from the starting point of the circumference along the winding direction to the first point is L3, and 0.5C2≤L3≤C2.

7. The battery cell according to any one of claims 1 to 3, characterized in that, The negative electrode sheet has a negative electrode winding end, and the positive electrode sheet has a positive electrode winding end. Along the winding direction, the negative electrode winding end extends beyond the positive electrode winding end.

8. The battery cell according to claim 7, characterized in that, The diaphragm has a winding end that extends beyond the negative electrode winding end along the winding direction.

9. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1 to 8.

10. An electrical appliance, characterized in that, Includes the battery device as described in claim 9.

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