Battery monomer, battery and electric device

Abstract

The utility model provides a battery monomer, a battery and a power utilization device. The battery monomer comprises a shell, an electrode assembly and a current collecting component, the electrode assembly comprises a first tab; the shell is used for accommodating the electrode assembly; the current collecting component comprises a first connecting part and a second connecting part; the first connecting part is electrically connected with the first tab; the second connecting part is connected with the first connecting part and protrudes in the direction away from the electrode assembly, the second connecting part comprises at least one first protruding part and at least one second protruding part, the height of the second protruding part is larger than that of the first protruding part, the at least one first protruding part is welded to the shell, and the at least one second protruding part is welded to the shell.

Description

[0001] Cross-referencing

[0002] This application incorporates Chinese Patent Application No. 202310200635.5, filed on March 3, 2023, entitled “Battery Cell, Battery and Electrical Device”, which is incorporated herein by reference in its entirety. Technical Field

[0003] This application relates to the field of battery technology, and in particular to a battery cell, a battery, and an electrical device. Background Technology

[0004] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development.

[0005] The current collector within a battery needs to conduct current generated by the electrode assembly to the electrode terminals to output electrical energy. The reliability of the conductive connection of the current collector has a significant impact on battery performance. The current collector is usually electrically connected to the casing by welding. During welding, high precision is required in the positioning and control of the welding path; otherwise, deviations in the welding position may lead to incomplete or missing welds, thus affecting the reliability of the connection between the current collector and the casing. Summary of the Invention

[0006] This application aims to at least solve one of the technical problems existing in the prior art. To this end, one object of this application is to provide a battery cell, a battery, and an electrical device to improve the reliability of the conductive connection between the current collector and the casing.

[0007] An embodiment of the first aspect of this application provides a battery cell including a housing, an electrode assembly, and a current collector. The electrode assembly includes a first tab; the housing defines a receiving space and an opening at one end of the receiving space for receiving the electrode assembly; the current collector is located within the receiving space near the opening; the current collector includes a first connecting portion and a second connecting portion; the first connecting portion is electrically connected to the first tab; the second connecting portion is connected to the first connecting portion and protrudes in a direction away from the electrode assembly, the second connecting portion includes at least one first protrusion and at least one second protrusion, the height of the second protrusion being greater than the height of the first protrusion, at least one first protrusion being welded to the housing, and at least one second protrusion being welded to the housing.

[0008] In the technical solution of this application embodiment, by setting the second connecting part connected to the shell as a first protrusion and a second protrusion with different heights, the welding area between the current collector and the shell can be increased, and the length of the welding seam between the current collector and the shell can be increased, thereby improving the reliability of the conductive connection between the current collector and the shell.

[0009] In some embodiments, the second connecting portion includes a plurality of first protrusions and a plurality of second protrusions, which are alternately arranged along the circumference of the electrode assembly. By alternately arranging a plurality of first protrusions and second protrusions of different heights, the end face of the second connecting portion facing away from the electrode assembly can be formed with an alternating surface height, which is more conducive to reducing the requirements for welding positioning accuracy, reducing incomplete or missing welds, and improving the reliability of the welded connection between the second connecting portion and the housing.

[0010] In some embodiments, the second connection portion further includes at least one stress relief portion, which is at least partially located between adjacent first and second protrusions. Providing a stress relief portion between adjacent first and second protrusions facilitates the welding of the current collector component into the housing.

[0011] In some embodiments, the stress relief portion is configured as a notch that extends through the second connection portion along its thickness direction. This notch configuration provides space for deformation of the second connection portion, facilitating stress relief during the insertion of the current collector into the housing and during welding.

[0012] In some embodiments, the stress relief portion includes a first portion and a second portion connected together. The first portion is disposed between adjacent first protrusions and second protrusions, and the second portion is disposed on the first connecting portion. Extending the stress relief portion to the first connecting portion can provide sufficient deformation margin, which is beneficial for stress relief.

[0013] In some embodiments, the first connecting portion includes a hollow portion, one end of the second portion is connected to the first portion, and the other end is connected to the hollow portion. By providing the hollow portion, the weight of the current collector can be reduced, which is beneficial to the lightweighting of the battery. Connecting the notch to the hollow portion can simplify the processing steps during manufacturing.

[0014] In some embodiments, the outer side of the second connecting portion abuts against the inner side of the housing. Setting the outer side of the second connecting portion to abut against the inner side of the housing reduces the gap between the current collector and the housing, which is beneficial for improving welding quality.

[0015] In some embodiments, the housing includes a third end face forming an opening, and the first end face of the first protrusion facing away from the first connecting portion and the second end face of the second protrusion facing away from the first connecting portion are both lower than the third end face. The third end face is higher than the first and second end faces, which can provide internal arrangement space for the weld formed by welding the current collecting member to the housing to reduce the risk of interference with other components.

[0016] In some embodiments, the minimum height difference between the second end face and the third end face of the second protrusion is greater than 0.4 mm. There is sufficient space between the second end face and the third end face to accommodate the first weld portion and reduce interference between the weld and other components.

[0017] In some embodiments, the second connecting portion is welded to the housing to form a first welded portion. A portion of the first welded portion is located at the joint between the side of the first protrusion and the inner side of the housing, and / or at the joint between the side of the second protrusion and the inner side of the housing. The side of the first protrusion and its first end face away from the first connecting portion are adjacent, and the side of the second protrusion and its second end face away from the first connecting portion are adjacent. A portion of the first welded portion may also be located at the joint between the side of the first protrusion and the inner side of the housing, and / or at the joint between the side of the second protrusion and the inner side of the housing. This increases the length of the first welded portion, thereby increasing the flow area between the current collector and the housing, improving flow capacity, and enhancing connection reliability.

[0018] In some embodiments, the second connecting portion is welded to the housing to form a first welded portion. Along the axial direction of the electrode assembly, the height H of the first welded portion from the first connecting portion satisfies: H2 ≤ H ≤ H1; where H1 is the maximum height of the second protrusion and H2 is the minimum height of the first protrusion. Controlling the height of the first welded portion between the maximum height of the second protrusion and the minimum height of the first protrusion can reduce the accuracy requirements for butt joint positioning during welding.

[0019] In some embodiments, the perimeter of the projection of the inner side of the housing onto a plane perpendicular to the axial direction of the electrode assembly is L, and the length L1 of the first welded portion satisfies L1≥0.2L. Setting the length L1 of the first welded portion to be greater than or equal to 0.2L can provide sufficient flow area between the current collector and the housing, thereby meeting the flow requirements of the current collector inside the battery.

[0020] In some embodiments, the first end face of the first protrusion away from the electrode assembly includes at least one protrusion, and / or the second end face of the second protrusion away from the electrode assembly includes at least one protrusion, wherein the at least one protrusion is one or more of square teeth, arc-shaped teeth, trapezoidal teeth, and triangular teeth. Setting the first and second end faces to include at least one protrusion can increase the length of the butt joint between the second connection portion and the housing, which is beneficial for the first welded portion to have sufficient length to meet current flow and connection requirements.

[0021] In some embodiments, the electrode assembly further includes a second tab, which is located at both ends of the electrode assembly, as well as the first tab. The housing includes a sidewall, an opening at one end of the sidewall, and an end wall at the other end of the sidewall. The battery cell further includes an end cap and an electrode lead-out portion. The end cap is closed to the opening and fixedly connected to the housing. The electrode lead-out portion is insulated through the end wall and electrically connected to the second tab. Electrically connecting the electrode assembly to the housing and the electrode lead-out portion respectively facilitates the input and output of electrical energy in the electrode assembly.

[0022] An embodiment of the second aspect of this application provides a battery comprising the battery cell described in the above embodiments.

[0023] An embodiment of the third aspect of this application provides an electrical device that includes the battery described in the above embodiments, the battery being used to provide electrical energy.

[0024] 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

[0025] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0026] Figure 1 This is a schematic diagram of the vehicle structure according to some embodiments of this application;

[0027] Figure 2 This is an exploded structural diagram of a battery according to some embodiments of this application;

[0028] Figure 3 This is an exploded structural diagram of a battery cell according to some embodiments of this application;

[0029] Figure 4 This is a schematic diagram of the structure of the current collection component in some embodiments of this application;

[0030] Figure 5 This is a partial cross-sectional view of a battery cell in some embodiments of this application;

[0031] Figure 6 This is a schematic diagram of the current collection component in some other embodiments of this application;

[0032] Figure 7 This is a schematic diagram of the structure of the current collection component according to some embodiments of this application;

[0033] Figure 8 This is a schematic diagram showing the welding connection between the current collection component and the housing in some embodiments of this application.

[0034] Figure 9 This is a schematic diagram showing the welding connection between the current collection component and the housing in some other embodiments of this application;

[0035] Figure 10 This is a schematic diagram showing the welding connection between the current collection component and the housing in some embodiments of this application.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1000 vehicles;

[0038] Battery 100, controller 200, motor 300;

[0039] Box 10, first sub-box 11, second sub-box 12;

[0040] Battery cell 20, housing 21, electrode assembly 22, first tab 221, current collector 23, first connecting part 231, second connecting part 232, first protrusion 2321, second protrusion 2322, stress relief part 2323, first part 2323A, second part 2323B, first end face 2321A, second end face 2322A, third end face 211, end cap 24, first welding part 25, first butt weld 251, second butt weld 252, electrode lead-out part 26, preset welding trajectory S1. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0046] 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).

[0047] 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", "circumferential", etc., 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 do not 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.

[0048] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the 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.

[0049] Currently, judging from market trends, the application of power batteries is becoming increasingly widespread. Power batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of power battery applications, market demand is also constantly increasing.

[0050] The applicant noted that the current collector inside the battery cell and the battery cell casing can be electrically connected by welding. For example, laser welding can be performed on the butt joint between the end face of the current collector and the inner side of the casing to form a butt weld. However, this connection method requires high dimensional accuracy and butt positioning accuracy of the current collector and the casing. If the dimensional tolerances of the mechanical structural parts (casing, current collector), the tolerances of the equipment and fixtures, and the cumulative tolerances of the positioning accuracy are large, the laser weld mark may be offset vertically, resulting in poor welding effect. For example, if the laser weld mark is offset upward, it will be separated from the butt joint position of the current collector and the casing, and thus the welding connection between the two cannot be achieved. Or, if the laser weld mark is offset downward, the laser will completely irradiate the surface of the current collector. Since the material of the current collector is different from that of the casing, the absorption rate of the laser is also different, which will cause a false weld between the current collector and the casing, and a reliable connection cannot be achieved.

[0051] To alleviate the problem of poor connection between the current collector and the shell, the applicant discovered that the butt joint between the flat end face of the current collector and the inner side of the shell is at the same height. Ideally, the weld is also a complete circumferential butt weld formed along this height. At this time, the flow area of ​​the weld is excessive. The end face structure design of the part where the current collector and the shell meet can be optimized to reduce the requirements for positioning accuracy during welding. This ensures that even if the welding path is offset, a weld mark of sufficient length can be formed between the current collector and the shell to achieve reliable connection and flow.

[0052] Based on the above considerations, in order to improve the reliability and current carrying capacity of the connection between the current collector and the casing, the applicant, after in-depth research, designed a battery cell with the end face of the current collector and the casing mating with end faces of different heights. This expands the height range of the mating area between the casing and the current collector of the battery cell. Even when the solder mark is misaligned, some current collectors and the casing can still form a good welded connection, so that a sufficiently long molten pool can be formed between the current collector and the casing, improving the reliability of the conductive connection, and reducing the requirements for the machining accuracy of parts, the alignment accuracy of tooling fixtures, and the welding control accuracy.

[0053] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system for such an electrical device can be constructed using battery cells and batteries disclosed in this application.

[0054] 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.

[0055] 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.

[0056] 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 100 is disposed inside the vehicle 1000, and the battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 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 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0057] In some embodiments of this application, the battery 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.

[0058] Please refer to Figure 2 , Figure 2This is an exploded structural diagram of a battery 100 provided in some embodiments of this application. The battery 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 the battery cell 20 and can have various structures. In some embodiments, the housing 10 may include a first sub-housing 11 and a second sub-housing 12, which overlap each other, jointly defining a space for accommodating the battery cell 20. The second sub-housing 12 may be a hollow structure with one open end, while the first sub-housing 11 may be a plate-like structure, covering the open side of the second sub-housing 12 so that the first sub-housing 11 and the second sub-housing 12 jointly define the space. Alternatively, both the first sub-housing 11 and the second sub-housing 12 may be hollow structures with one open side, with the open side of the first sub-housing 11 covering the open side of the second sub-housing 12. Of course, the box 10 formed by the first sub-box 11 and the second sub-box 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0059] In battery 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, battery 100 can also be composed of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the housing 10. Battery 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0060] 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.

[0061] Please refer to Figures 3-5 , Figure 3 This is an exploded structural diagram of a battery cell 20 provided in some embodiments of this application. Figure 4 This is a schematic diagram of the structure of the current collection component 23 provided in some embodiments of this application. Figure 5This is a partial cross-sectional view of a battery cell 20 provided in some embodiments of this application. The battery cell 20 refers to the smallest unit constituting a battery. The battery cell 20 includes a housing 21, an electrode assembly 22, a current collector 23, and other functional components. The electrode assembly 22 includes a first tab 221; the housing 21 defines a receiving space and an opening at one end of the receiving space for accommodating the electrode assembly 22; the current collector 23 is located within the receiving space near the opening; the current collector 23 includes a first connecting portion 231 and a second connecting portion 232; the first connecting portion 231 is electrically connected to the first tab 221; the second connecting portion 232 is connected to the first connecting portion 231 and protrudes in a direction away from the electrode assembly 22, the second connecting portion 232 includes at least one first protrusion 2321 and at least one second protrusion 2322, the height of the second protrusion 2322 being greater than the height of the first protrusion 2321, at least one first protrusion 2321 being welded to the housing 21, and at least one second protrusion 2322 being welded to the housing 21.

[0062] The housing 21 is a component that forms the internal environment of the battery cell 20, wherein the formed internal environment can accommodate the electrode assembly 22, electrolyte, and other components. The housing 21 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 21 can be determined according to the specific shape and size of the electrode assembly 22. The material of the housing 21 can 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.

[0063] Electrode assembly 22 is the component in the battery cell 20 where electrochemical reactions occur. The casing 21 may contain one or more electrode assemblies 22. The electrode assembly 22 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the electrode assembly, while the portions without active material each constitute a tab. The tab can be divided into a first tab and a second tab, one of which is the positive tab and the other the negative tab. The first and second tabs can 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 and negative active materials react with the electrolyte, and the tabs connect to the electrode leads to form a current loop.

[0064] The first electrode 221 can be connected to the current collector 23 and electrically connected to the housing 21 through the current collector 23. In this way, the housing 21 can serve as the electrode lead-out part of the first electrode 221 for inputting or outputting electrical energy.

[0065] The current collector 23 is located within the receiving space of the housing 21 near the opening and is connected to the first tab 221 of the electrode assembly 22 and the housing 21, respectively, to conduct the current generated by the electrode assembly 22 to the housing 21. The shape of the current collector 23 can be adapted to the shape of the housing 21. For example, if the housing 21 is cylindrical, the first connecting portion 231 of the current collector 23 is also circular, and the second connecting portion 232 can be located at the outer edge of the circular first connecting portion 231 and protrude in a direction away from the electrode assembly 22.

[0066] Since the current collector 23 is located inside the shell 21, welding is constrained by the internal space. Furthermore, butt welding requires high precision in the machining dimensions and positioning of the components to be welded; otherwise, a significant deviation will occur between the actual welding position and the preset welding path. Because the current collector 23 and the shell 21 are often made of different materials, their welding performance also differs. Taking laser welding as an example, the laser power during butt welding is maintained at a set value to achieve fusion connection of the components at the butt joint. If the laser beam is not directed at the butt joint, i.e., welding misalignment occurs, the set laser power will... It may not be able to meet the requirements for weld pool formation under other conditions. For example, when the actual welding position shifts towards the direction closer to the electrode assembly, the laser is no longer directed at the butt joint between the second connection 232 of the current collector 23 and the housing 21, but is instead directed entirely at the surface of the second connection 232. In this case, to form a weld pool, the laser needs to penetrate the second connection to form a deep penetration weld. However, the laser power required for deep penetration welding is greater than that required for butt welding. At this time, the set laser power cannot meet the requirements for weld pool formation, and a false weld or incomplete weld will occur between the second connection 232 and the housing 21. When the actual welding position shifts towards the direction closer to the opening of the housing 21, the area irradiated by the laser may not have the current collector 23, so it is impossible to form a fusion weld between the current collector 23 and the housing 21.

[0067] The first connecting portion 231 includes a first side surface and a second side surface opposite to each other. The first side surface is the surface away from the electrode assembly 22, and the second side surface is the surface facing the electrode assembly 22. The second connecting portion 232 is located on the first side surface of the first connecting portion 231 and protrudes in a direction away from the electrode assembly 22.

[0068] The second connecting portion 232 includes a first protrusion 2321 and a second protrusion 2322. The height of the second protrusion 2322 refers to the distance from the first side of the first connecting portion 231 along the axial direction of the electrode assembly 22. The height of the first protrusion 2321 refers to the distance from the first side of the first connecting portion 231 along the axial direction of the electrode assembly 22. There can be one or more first protrusions 2321, and there can be one or more second protrusions 2322. Multiple first protrusions 2321 and multiple second protrusions 2322 can be alternately arranged; for example, a first protrusion 2321 is provided between two adjacent second protrusions 2322. Alternatively, multiple first protrusions 2321 and multiple second protrusions 2322 can be non-alternating; for example, multiple first protrusions 2321 are provided between two adjacent second protrusions 2322.

[0069] The first protrusion 2321 and the second protrusion 2322 have different heights, so that part of the weld formed between the second connecting part 232 and the housing 21 is located between the first protrusion 2321 and the housing 21, and part of it is located between the second protrusion 2322 and the housing 21.

[0070] It is understood that the second connecting portion 232 may also include at least one protrusion with a height different from that of the first protrusion 2321 and the second protrusion 2322. This allows the mating positions between the second connecting portion 232 and the housing 21 to be distributed at different heights along the axial direction of the electrode assembly, which is beneficial to forming a sufficient weld length even when the welding position is offset.

[0071] In this embodiment, the second connecting portion 232 includes a first protrusion 2321 and a second protrusion 2322 of different heights. As a result, the mating seam between the second connecting portion 232 and the housing 21 is no longer at the same height position, but is distributed at multiple different heights along the axial direction of the electrode assembly 22. This increases the mating area between the current collector 23 and the housing 21 that can be welded, and increases the length of the mating seam between the current collector 23 and the housing 21. In this way, even if the actual welding position deviates from the preset welding position, there can still be a corresponding mating seam available for welding to form a fusion weld, thereby improving the reliability of the connection between the current collector 23 and the housing 21.

[0072] In some embodiments, the second connection portion 232 includes a plurality of first protrusions 2321 and a plurality of second protrusions 2322, the first protrusions 2321 and the second protrusions 2322 being alternately spaced along the circumference of the electrode assembly 22.

[0073] The second connecting portion 232 includes a first protrusion 2321 and a second protrusion 2322. The first protrusion 2321 and the second protrusion 2322 are alternately arranged along the circumference of the electrode assembly 22. The height of the first protrusion 2321 and the second protrusion 2322 respectively refers to the height of their protrusion relative to the first connecting portion 231. For example, the height of the first protrusion 2321 can be the height of its end surface away from the first connecting portion 231 relative to the first side surface, and the height of the second protrusion 2322 can be the height of its end surface away from the first connecting portion 231 relative to the first side surface.

[0074] In this embodiment, by alternately setting multiple first protrusions 2321 and second protrusions 2322 of different heights, the surface of the second connecting part 232 away from the electrode assembly 22 can be formed into a surface with alternating heights, which is more conducive to reducing the requirements for welding positioning accuracy, reducing the number of false welds or missing welds caused by insufficient welding accuracy, and improving the reliability of the welding connection between the second connecting part 232 and the housing 21.

[0075] Please see Figure 6 , Figure 6 This is a schematic diagram of the current collection member 23 according to other embodiments of this application. In some embodiments, the second connection portion 232 further includes at least one stress relief portion 2323, which is at least partially located between the adjacent first protrusion 2321 and the second protrusion 2322.

[0076] Before welding, the current collector 23 needs to be assembled into a designated position inside the housing 21. During welding, the second connecting part 232 needs to be kept in close contact with the housing 21 to reduce the gap between them so that a fusion weld that meets quality requirements can be formed. Therefore, the outer ring size of the current collector 23 needs to match the inner ring size of the housing 21 as closely as possible. This can easily lead to the housing 21 squeezing the current collector 23 during insertion, causing the current collector 23 to undergo uncontrollable deformation due to extrusion stress, which in turn affects the positioning of the assembly and welding. Similarly, the thermal stress generated during welding may also cause stress deformation of the current collector 23, which is detrimental to maintaining positioning accuracy and welding accuracy.

[0077] The stress relief section 2323 can promptly conduct and release the compressive stress or welding thermal stress on the second connecting part 232 when the current collector 23 is inserted into the shell or during welding. In particular, since the first protrusion 2321 and the second protrusion 2322 have different heights, stress concentration is likely to occur at their junction. The stress relief section 2323 is located between adjacent first protrusions 2321 and second protrusions 2322, which can alleviate the stress concentration at the junction of the first protrusion 2321 and the second protrusion 2322, reduce the impact of stress deformation on the surrounding structure, and alleviate the insufficient alignment accuracy or welding accuracy caused by stress, which is beneficial for the assembly and welding of the current collector 23 into the shell.

[0078] The stress relief portion 2323 can be configured as a weak portion located between the first protrusion 2321 and the second protrusion 2322. The structural strength of this weak portion is weaker than that of the first and second protrusions 2321 and 2322, allowing stress to be released through structural deformation and reducing the risk of structural failure due to stress concentration. In one example, the weak portion can be a groove recessed in the thickness direction of the second connecting portion 232. In this case, the thickness of the weak portion is thinner than that of the adjacent first and second protrusions 2321 and 2322, thus allowing for greater deformation under stress to release stress. In other examples, the stress relief portion 2323 can also be configured as an elastic portion with a certain degree of elasticity, allowing stress to be released through elastic deformation. In still other examples, the stress relief portion 2323 can be a hole or groove penetrating the thickness of the second connecting portion 232, allowing stress relief through the free edge of the edge. It should be noted that the structural form of the stress relief portion 2323 described in this embodiment is illustrative and should not be considered a limitation of this embodiment.

[0079] In some embodiments, such as Figure 6 As shown, the stress relief part 2323 is constructed as a notch, which penetrates the second connecting part 232 along the thickness direction of the second connecting part 232.

[0080] The stress relief portion 2323 can be a notch located between adjacent first protrusions 2321 and second protrusions 2322. The notch penetrates the second connecting portion 232 along its thickness direction, forming a through groove between adjacent first protrusions 2321 and second protrusions 2322. The bottom of the groove is lower than the height of the first connecting portion 231 than the height of the first protrusion 2321 and the height of the second protrusion 2322. In this way, the edges of the first protrusion 2321 and the second protrusion 2322 near the groove form free edges, which can deform under stress to achieve stress relief.

[0081] The stress relief section 2323 is constructed with a notch to release stress in a timely manner, control the range of influence of stress deformation, and help maintain the accuracy of assembly positioning and welding.

[0082] Please see Figure 7 , Figure 7 This is a schematic diagram of the current collection member 23 according to some embodiments of this application. In some embodiments, the stress relief part 2323 includes a first part 2323A and a second part 2323B connected together. The first part 2323A is disposed between the adjacent first protrusion 2321 and the second protrusion 2322, and the second part 2323B is disposed on the first connecting part 231.

[0083] The second part 2323B is located on the first connecting part 231, meaning that the stress relief part 2323 extends from the second connecting part 232 to the first connecting part 231. This ensures that the first protrusion 2321 and the second protrusion 2322 on both sides of the stress relief part 2323 are completely separated by the stress relief part 2323. The first part 2323A and the second part 2323B can have the same or different structural forms. In one example, the first part 2323A is a notch that penetrates the second connecting part 232 along the thickness direction of the second connecting part 232, and the second part 2323B can be a groove that is recessed along the thickness direction of the first connecting part 231. Alternatively, the second part 2323B can also be a notch that penetrates the first connecting part 231 along the thickness direction of the first connecting part 231, forming a communicating groove-shaped notch between the first part 2323A and the second part 2323B.

[0084] The stress relief portion 2323 extends to the first connecting portion 231, which is more conducive to blocking the negative effects caused by stress deformation. The second portion 2323B is provided on the first connecting portion 231, which can also provide space for stress relief for the outer edge of the first connecting portion 231.

[0085] In some embodiments, such as Figure 7 As shown, the first connecting part 231 includes a hollow part 2312, one end of the second part 2323B is connected to the first part 2323A, and the other end is connected to the hollow part 2312.

[0086] The first connecting portion 231 may include a tab connecting portion 2311 and a hollow portion 2312, wherein the hollow portion 2312 refers to a hollow structure that penetrates the first connecting portion 231 along its thickness direction. The tab connecting portion 2311 is used for welding connection with the first tab 221. The hollow portion 2312 may include multiple spaced hollow areas, with the tab connecting portion 2311 located between adjacent hollow areas.

[0087] In one example, the first part 2323A penetrates the notch of the second connecting part 232 along the thickness direction of the second connecting part 232, and the second part 2323B may penetrate the notch of the first connecting part 231 along the thickness direction of the first connecting part 231. One end of the second part 2323B is connected to the first part 2323A, and the other end is connected to the hollow part 2312, so that the first part 2323A and the hollow part 2312 form a connected hollow structure.

[0088] By setting the hollow part 2312, the weight of the current collector 23 can be reduced, which is beneficial to the lightweighting of the battery cell 20. By connecting the stress relief part 2323 with the hollow part 2312, the outer edge of the current collector 23 can be divided into multiple relatively independent substructures, which is beneficial to the assembly positioning and welding positioning of the current collector 23, thereby improving the reliability of the connection.

[0089] In some embodiments, the outer side of the second connecting portion 232 abuts against the inner side of the housing 21.

[0090] The outer surface of the second connecting portion 232 refers to the surface of the second connecting portion 232 away from the axis of the electrode assembly 22, and the inner surface of the housing 21 refers to the surface facing the electrode assembly 22. During assembly, the current collector 23 needs to be inserted into the housing 21, and the outer surface of the second connecting portion 232 is aligned with the inner surface of the housing 21 before welding to form a weld. "Abutting" refers to the contact between the outer surface of the second connecting portion 232 and the inner surface of the housing 21 during alignment, reducing the gap between them and lowering the possibility of incomplete or missed welds. In one example, the outer surface of the second connecting portion 232 and the inner surface of the housing 21 can form an interference fit to ensure abutting contact.

[0091] Setting the outer side of the second connecting part 232 and the inner side of the housing 21 to abut against each other can minimize the gap between them and improve the welding quality.

[0092] Please see Figure 8 , Figure 8 This is a schematic diagram of the welding connection between the current collecting member 23 and the housing 21 in some embodiments of this application. In some embodiments, the housing 21 includes a third end face 211 forming an opening, and the first protrusion 2321 facing away from the first end face 2321A of the first connecting portion 231 and the second protrusion 2322 facing away from the second end face 2322A of the first connecting portion 231 are both lower than the third end face 211.

[0093] The first end face 2321A and the second end face 2322A are both lower than the third end face 211. This means that when the current collector 23 is assembled into the housing 21, along the axial direction of the electrode assembly 22, the highest point of the first end face 2321A and the second end face 2322A (when not planar) remains lower than the third end face 211.

[0094] In this embodiment, the third end face 211 is higher than the first end face 2321A and the second end face 2322A, which allows the current collecting member 23 to be completely contained within the receiving space formed by the housing 21 without protruding from the housing 21, thereby preventing interference with other members.

[0095] In some embodiments, such as Figure 8 As shown, the minimum height difference H3 between the second end face 2322A and the third end face 211 is greater than 0.4 mm.

[0096] Considering that the second end face 2322A and the third end face 211 may not be planar, but may be curved surfaces, the minimum height difference H3 between the second end face 2322A and the third end face 211 refers to the distance between the two closest points between the second end face 2322A and the third end face 211 along the axial direction of the electrode assembly 22.

[0097] Setting the height difference between the second end face 2322A and the third end face 211 to be greater than 0.4 mm can provide sufficient space for the butt weld between the second connecting part 232 and the housing 21. On the other hand, the inner surface of the housing 21 is also the surface to be melted during welding. Since welding will generate certain welding stress and cause welding deformation, there is sufficient space between the second end face 2322A and the third end face 211 to accommodate the butt weld and reduce the risk of interference.

[0098] Please see Figure 9 and Figure 10 , Figure 9 This is a schematic diagram showing the welding connection between the current collecting member 23 and the housing 21 in other embodiments of this application. Figure 10 This is a schematic diagram of the welding connection between the current collector 23 and the housing 21 in some embodiments of this application. In some embodiments, the second connecting portion 232 is welded to the housing 21 to form a first weld portion 25. A portion of the first weld portion 25 is located at the joint between the side of the first protrusion 2321 and the inner side of the housing 21, and / or at the joint between the side of the second protrusion 2322 and the inner side of the housing 21. The side of the first protrusion 2321 is adjacent to the first end face 2321A of the first protrusion 2321 facing away from the first connecting portion 231, and the side of the second protrusion 2322 is adjacent to the second end face 2322A of the second protrusion 2322 facing away from the first connecting portion 231.

[0099] The first protrusion 2321 and the second protrusion 2322 have different heights. The mating seam formed between the second connecting portion 232 and the housing 21 may include, in addition to the mating seams formed between the first end face 2321A, the second end face 2322A and the inner side surface of the housing 21, the mating seam formed between the side of the first protrusion 2321 and the inner side surface of the housing 21, and / or the mating seam formed between the side of the second protrusion 2322 and the inner side surface of the housing 21. For example... Figure 9 As shown, the first protrusion 2321 and the second protrusion 2322 are alternately arranged to form a serrated surface with square teeth. When the welding position shifts, the weld formed between the second connecting part 232 and the housing 21 includes a first butt weld 251 formed at the butt joint between the first end face 2321A and the housing 21 and / or the butt joint between the second end face 2322A and the housing 21, and also includes a second butt weld 252 at the butt joint between the side of the first protrusion 2321 and the housing 21 and / or the butt joint between the side of the second protrusion 2322 and the housing 21. The length of the first welded part 25 thus formed includes the length of the first butt weld 251 and the length of the second butt weld 252.

[0100] In one example, such as Figure 10 As shown, a stress relief portion 2323 with a notch is provided between the first protrusion 2321 and the second protrusion 2322. The bottom of the stress relief portion 2323, the side of the first protrusion 2321, and the side of the second protrusion 2322 also form a part of the butt joint between the second connecting portion 232 and the housing 21. The first fusion portion 25 formed during welding can include the first butt weld 251 between the first end face 2321A and the housing 21 and between the second end face 2322A and the housing 21, and can also include the second butt weld 252 between the side of the first protrusion 2321 and the side of the second protrusion 2322 and the housing 21.

[0101] In this embodiment, a portion of the first welded portion 25 may also be located at the joint between the side of the first protrusion 2321 and the inner side of the housing 21, and / or at the joint between the side of the second protrusion 2322 and the inner side of the housing 21. This can increase the length of the first welded portion 25, thereby increasing the flow area between the current collector 23 and the housing 21, improving the flow capacity and the reliability of the connection.

[0102] In some embodiments, the second connecting portion 232 is welded to the housing 21 to form a first fusion portion 25. Along the axial direction of the electrode assembly 22, the height H of the first fusion portion 25 from the first connecting portion 231 satisfies: H2≤H≤H1; where H1 is the maximum height of the second protrusion 2322 and H2 is the minimum height of the first protrusion 2321.

[0103] The end face of the second connecting part 232 away from the electrode assembly 22 is no longer a plane at the same height, but a surface with alternating heights. When welding the second connecting part 232 to the housing 21 to form the first welded part 25, the preset welding trajectory S1 may no longer be a trajectory with a fixed height, but a welding trajectory with fluctuating welding position, as long as it can at least partially overlap with the butt joint of the second connecting part 232 and the housing 21, so that the first welded part 25 formed by welding has sufficient length to meet the requirements of connection and current flow.

[0104] In one example, the preset welding trajectory S1 for forming the first welded portion 25 can completely coincide with the butt joint of the second connecting portion 232 and the housing 21. Since the end of the second connecting portion 232 away from the electrode assembly 22 has an uneven surface, the length of the butt joint between the second connecting portion 232 and the housing 21 will increase. At this time, the preset welding trajectory S1 completely coincides with the butt joint. Even if there is a false weld or missing weld due to error, the length of the first welded portion 25 can be relatively increased, thereby meeting the requirements of connection and current flow.

[0105] The height H of the first welded part 25 from the first connecting part 231 is between the minimum height H2 of the first protrusion 2321 and the maximum height H1 of the second protrusion 2322. This means that the preset welding trajectory S1 also varies between the minimum height H2 of the first protrusion 2321 and the maximum height H1 of the second protrusion 2322. This is equivalent to increasing the fluctuation range of the preset welding trajectory S1, thereby reducing the accuracy requirements of the butt joint positioning during welding.

[0106] In some embodiments, the perimeter of the projection of the inner side of the housing 21 onto a plane perpendicular to the axial direction of the electrode assembly 22 is L (not shown in the figure), and the length L1 (not shown in the figure) of the first welded portion 25 satisfies L1≥0.2L.

[0107] The projection of the inner surface of the housing 21 onto a plane perpendicular to the axial direction of the electrode assembly 22 is a closed line. For example, the projection of the inner surface of a cylindrical housing 21 onto a plane perpendicular to the axial direction of the electrode assembly 22 is a circle, and the circumference L of this projection is the length of the circle. The length L1 of the first weld portion 25 is the cumulative length of the butt weld formed between the second connecting portion 232 and the housing 21. In some examples, the length L1 of the first weld portion 25 includes the cumulative length of the first butt weld 251 and the cumulative length of the second butt weld 252.

[0108] In some embodiments, the length L1 of the first welded portion satisfies L1≥0.33L. This increases the flow area between the current collector 23 and the housing 21, thereby improving the reliability of the welded connection.

[0109] Setting the length L1 of the first welded part 25 to be greater than or equal to 0.2L can provide sufficient flow area between the current collector 23 and the housing 21, thereby meeting the flow requirements of the current collector 23 in the battery and improving the reliability of the connection between the current collector 23 and the housing 21.

[0110] In some embodiments, the first end face 2321A of the first protrusion 2321 away from the electrode assembly 22 includes at least one protrusion, and / or the second end face 2322A of the second protrusion 2322 away from the electrode assembly includes at least one protrusion, wherein the at least one protrusion is one or more of square teeth, arc teeth, trapezoidal teeth and triangular teeth.

[0111] The first end face 2321A and / or the second end face 2322A can be non-flat surfaces. For example, the first end face 2321A may include a protrusion, making it a non-flat surface that is high in the middle and low on both sides. In one example, the first end face 2321A may also include multiple protrusions, making it a continuous serrated surface. The protrusions can be raised tooth-like structures, such as square teeth, arc-shaped teeth, trapezoidal teeth, or triangular teeth, or a combination thereof. The second end face 2322A may also include one or more protrusions, and the structural form of the second end face 2322A may be the same as or different from that of the first end face 2321A; this embodiment does not limit this.

[0112] Setting the first end face 2321A and / or the second end face 2322A to include at least one protrusion can increase the length of the butt joint between the second connecting portion 232 and the housing 21, which is beneficial for welding to form a first weld portion 25 with sufficient length to meet the requirements of flow and connection.

[0113] In some embodiments, the electrode assembly 22 further includes a second tab 222, which is located at both ends of the electrode assembly 22, and the housing 21 includes a side wall 212, an opening at one end of the side wall 212, and an end wall 213 at the other end of the side wall 212. The battery cell 20 further includes an end cap 24 and an electrode lead-out portion 26. The end cap 24 covers the opening and is fixedly connected to the housing 21. The electrode lead-out portion 26 is insulated through the end wall 213 and electrically connected to the second tab 222.

[0114] End cap 24 refers to a component that covers the opening of housing 21 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 24 can be adapted to the shape of housing 21 to fit it. In some embodiments, end cap 24 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that end cap 24 is less prone to deformation under pressure and impact, enabling battery cell 20 to have higher structural strength and improved safety performance. Functional components such as electrode terminals can be provided on end cap 24. Electrode terminals can be used for electrical connection with electrode assembly 22 for outputting or inputting electrical energy into battery cell 20. In some embodiments, end cap 24 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 24 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 24. The insulating element can be used to isolate the electrical connection components within the housing 21 from the end cap 24 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0115] The housing 21 and the end cap 24 can be independent components, or the end cap 24 and the housing 21 can be integrated. Specifically, the end cap 24 and the housing 21 can form a common connection surface before other components are installed in the housing. When it is necessary to encapsulate the interior of the housing 21, the end cap 24 can then cover the housing 21.

[0116] In this embodiment, the first tab 221 and the second tab 222 are respectively disposed at both ends of the electrode assembly 22 and are electrically connected to the housing 21 and the electrode lead-out portion 26 respectively, which is beneficial to the power input and output of the electrode assembly 22.

[0117] An embodiment of the second aspect of this application provides a battery 100, which includes the battery cell 20 in the above embodiments.

[0118] An embodiment of the third aspect of this application provides an electrical device that includes the battery 100 described in the above embodiments, the battery 100 being used to provide electrical energy.

[0119] The battery cell 20 in this application will be further described in detail below through an embodiment.

[0120] The battery cell 20 includes a housing 21, an electrode assembly 22, a current collector 23, an end cap 24, and an electrode lead-out portion 26.

[0121] The housing 21 includes a sidewall 212, an opening at one end of the sidewall 212, and an endwall 213 at the other end of the sidewall 212. The housing 21 defines a receiving space for accommodating the electrode assembly 22.

[0122] The electrode assembly 22 also includes a second tab 222, which is located at both ends of the electrode assembly 22, along with the first tab 221.

[0123] The current collector 23 is located at one end of the receiving space near the opening; the current collector 23 includes a first connecting portion 231 and a second connecting portion 232; the first connecting portion 231 is electrically connected to the first electrode tab 221; the second connecting portion 232 is connected to the first connecting portion 231 and protrudes in a direction away from the electrode assembly 22, the second connecting portion 232 includes at least one first protrusion 2321 and at least one second protrusion 2322, the height of the second protrusion 2322 is greater than the height of the first protrusion 2321, at least one first protrusion 2321 is welded to the housing 21, and at least one second protrusion 2322 is welded to the housing 21. The first protrusion 2321 and the second protrusion 2322 are alternately arranged along the circumference of the electrode assembly 22.

[0124] The second connecting portion 232 also includes a stress relief portion 2323 located between the adjacent first protrusion 2321 and second protrusion 2322, the stress relief portion 2323 being configured as a notch penetrating the second connecting portion along the thickness direction of the second connecting portion 232.

[0125] The end cap 24 closes to the opening and is fixedly connected to the housing 21; the electrode lead-out part 26 is insulated through the end wall 213 and electrically connected to the second electrode tab 222.

[0126] The second connecting portion 232 is welded to the housing 21 to form a first weld portion 25. The first weld portion 25 includes a first butt weld 251 formed at the joint between the first end face 2321A and the housing 21, and / or the second end face 2322A and the housing 21, and a second butt weld 252 formed at the joint between the side of the first protrusion 2321 and the housing 21, and / or the joint between the side of the second protrusion 2322 and the housing 21. The perimeter of the projection of the inner side of the housing 21 onto a plane perpendicular to the axial direction of the electrode assembly is L, and the length L1 of the first weld portion 25 satisfies L1≥0.2L.

[0127] 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: Electrode assembly, including a first electrode tab; The housing defines a receiving space and an opening at one end of the receiving space for receiving the electrode assembly; A flow collection component is located within the receiving space at one end near the opening; The current collection component includes: The first connecting part is electrically connected to the first electrode ear; The second connecting portion is connected to the first connecting portion and protrudes in a direction away from the electrode assembly. The second connecting portion includes a plurality of first protrusions and a plurality of second protrusions. The height of the second protrusions is greater than the height of the first protrusions. At least one first protrusion is welded to the housing, and at least one second protrusion is welded to the housing. The first protrusions and the second protrusions are alternately arranged along the circumference of the electrode assembly. The second connection portion further includes at least one stress relief portion, which is at least partially located between the adjacent first protrusion and the second protrusion.

2. The battery cell according to claim 1, wherein, The stress relief section is constructed as a notch, which penetrates the second connection section along the thickness direction of the second connection section.

3. The battery cell according to claim 2, wherein, The stress relief portion includes a first part and a second part connected together. The first part is disposed between the first protrusion and the second protrusion which are adjacent to each other, and the second part is disposed on the first connecting part.

4. The battery cell according to claim 3, wherein, The first connecting part includes a hollow part, and one end of the second part is connected to the first part, and the other end is connected to the hollow part.

5. The battery cell according to any one of claims 1 to 4, wherein, The outer side of the second connecting part abuts against the inner side of the housing.

6. The battery cell according to any one of claims 1 to 4, wherein, The housing includes a third end face forming the opening, and the first end face of the first protrusion facing away from the first connecting portion and the second end face of the second protrusion facing away from the first connecting portion are both lower than the third end face.

7. The battery cell according to claim 6, wherein, The minimum height difference between the second end face and the third end face of the second protrusion is greater than 0.4 mm.

8. The battery cell according to any one of claims 1 to 4, wherein, The second connecting portion is welded to the housing to form a first welded portion. A portion of the first welded portion is located at the joint between the side of the first protrusion and the inner side of the housing, and / or at the joint between the side of the second protrusion and the inner side of the housing. Wherein, the side surface of the first protrusion is adjacent to the first end face of the first protrusion that is away from the first connecting portion, and the side surface of the second protrusion is adjacent to the second end face of the second protrusion that is away from the first connecting portion.

9. The battery cell according to any one of claims 1 to 4, wherein, The second connecting part is welded to the housing to form a first fusion joint. Along the axial direction of the electrode assembly, the height H of the first fusion joint from the first connecting part satisfies: H2≤H≤H1. Wherein, H1 is the maximum height of the second protrusion from the first connecting part, and H2 is the minimum height of the first protrusion from the first connecting part.

10. The battery cell according to claim 9, wherein, The perimeter of the projection of the inner side of the housing onto a plane perpendicular to the axial direction of the electrode assembly is L, and the length L1 of the first welded portion satisfies L1≥0.2L.

11. The battery cell according to any one of claims 1 to 4, wherein, The first protrusion, located away from the first end face of the electrode assembly, includes at least one protrusion, and / or the second protrusion, located away from the second end face of the electrode assembly, includes at least one protrusion, wherein the at least one protrusion is one or more of square teeth, arc-shaped teeth, trapezoidal teeth, and triangular teeth.

12. The battery cell according to any one of claims 1 to 4, wherein, The electrode assembly further includes a second tab, which is located at one end of the electrode assembly, as is the first tab. The housing includes a sidewall, an opening at one end of the sidewall, and an endwall at the other end of the sidewall; The battery cell also includes: End cap, which covers the opening and is fixedly connected to the housing; and The electrode lead-out portion is insulated and passes through the end wall and is electrically connected to the second electrode tab.

13. A battery, characterized in that, Includes the battery cell as described in any one of claims 1 to 12.

14. An electrical appliance, characterized in that, Includes the battery as described in claim 13, the battery being used to provide electrical energy.

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