Battery cell, its manufacturing method and manufacturing system, battery, and electrical device

Abstract

An embodiment of the present application provides a battery cell, a manufacturing method and a manufacturing system thereof, a battery, and an electrical device. The battery cell includes: a housing having an opening; an electrode assembly accommodated in the housing; and an end cap including a cap body and a convex portion. The cap body at least partially surrounds the outside of the convex portion and is used for laser welding with the housing so that the end cap covers the opening. In the thickness direction of the end cap, the convex portion protrudes from the inner surface of the cap body in the direction facing the electrode assembly and is used for blocking the laser when welding the cap body and the housing. A first recess is formed at a position corresponding to the convex portion on the end cap, which recesses from the outer surface of the cap body in the direction facing the electrode assembly. The first recess is used for releasing stress when welding the cap body and the housing. The present application can reduce the risk of burning of the internal components of the housing and improve the sealing performance and safety performance of the battery cell when welding the housing and the end cap.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to a battery cell and a manufacturing method and system thereof, a battery, and an electrical device. Background Art

[0002] Battery cells are widely used in electronic devices, such as mobile phones, laptop computers, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and electric tools, etc. Battery cells can include nickel-cadmium battery cells, nickel-hydrogen battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells, etc.

[0003] In the development of battery technology, in addition to improving the performance of battery cells, safety is also an issue that cannot be ignored. If the safety of battery cells cannot be guaranteed, the battery cells cannot be used. Therefore, how to enhance the safety of battery cells is a technical problem that needs to be solved urgently in battery technology. Summary of the invention

[0004] The present application provides a battery cell and a manufacturing method and system thereof, a battery, and an electrical device, which can improve the safety of the battery cell.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, including:

[0006] a housing having an opening;

[0007] an electrode assembly housed in the housing; and

[0008] The end cover comprises a cover body and a convex portion, wherein the cover body at least partially surrounds the outer side of the convex portion and is used for laser welding with the shell so that the end cover covers the opening;

[0009] In the thickness direction of the end cap, the convex portion protrudes from the inner surface of the cap body in a direction facing the electrode assembly and is used to block the laser when welding the cap body and the shell;

[0010] A first recessed portion is formed on the end cover at a position corresponding to the convex portion and is recessed from the outer surface of the cover body in a direction facing the electrode assembly. The first recessed portion is used to release stress when welding the cover body and the shell.

[0011] In the above solution, the laser acts on the abutting portion of the housing and the cover body to weld the housing and the cover body. The convex portion protrudes from the inner surface of the cover body. Therefore, when the laser enters the housing along the gap at the abutting portion, the convex portion can block the laser and reduce the risk of laser burning other components. In this embodiment, a first concave portion is further provided on the side of the convex portion facing away from the electrode assembly to reduce the strength of the convex portion. During the welding process, the convex portion can deform to release the welding stress, thereby reducing the risk of deformation and cracking in the welding area and improving the sealing performance.

[0012] In some embodiments, the housing has an outer end face surrounding the opening, and the outer end face of the housing is welded to the inner surface of the cover body so that the housing and the cover body are connected as a whole.

[0013] In the above solution, the inner surface of the cover body is abutted against the outer end face, which can reduce the internal space of the housing occupied by the cover body. When assembling the end cover and the housing, the outer end face can play a role in limiting the position in the thickness direction of the end cover.

[0014] In some embodiments, in the thickness direction, the bottom surface of the first concave portion is closer to the electrode assembly as a whole than the inner surface of the cover body.

[0015] The above solution can ensure the degree of protrusion of the convex portion from the inner surface of the cover body to more effectively block the laser and reduce the risk of laser burning the electrode assembly. At the same time, on the premise of ensuring the protrusion degree of the convex portion, this solution further ensures the degree of depression of the first concave portion so that the convex portion can deform to release the welding stress.

[0016] In some embodiments, the housing includes a side wall that extends in the thickness direction and surrounds the outer periphery of the electrode assembly. The convex portion includes a blocking surface facing the side wall, and the blocking surface is parallel to the thickness direction and extends from the inner surface of the cover body in the direction facing the electrode assembly.

[0017] In the above solution, when welding the side wall and the cover body, the laser irradiates on the blocking surface through the gap between the outer end face and the inner surface of the cover body, and the blocking surface and the side wall are arranged in parallel, and the two can limit the reflection direction of the laser, reducing the risk of laser burning other components inside the housing to a certain extent.

[0018] In some embodiments, the convex portion further includes a guiding surface facing the side wall. The guiding surface is connected to the end of the blocking surface away from the inner surface of the cover body, and the guiding surface is inclined in a direction away from the side wall compared with the blocking surface to guide the convex portion to be inserted into the housing.

[0019] In the above solution, by providing an inclined guiding surface on the convex portion, the convex portion can be guided to be inserted into the housing when assembling the end cover and the housing, so as to simplify the assembly process and improve the assembly efficiency.

[0020] In some embodiments, a connecting portion is formed between the top end surface of the protrusion and the bottom surface of the first recess, and the connecting portion is used for welding to the first electrode tab of the electrode assembly.

[0021] In the above solution, the connecting portion of the protrusion can be directly welded to the first electrode tab without other transition components, thereby simplifying the structure of the battery cell.

[0022] In some embodiments, the cover body includes a first plate body and a second plate body, the first plate body surrounds the outer side of the protrusion and is used for laser welding with the shell, and the protrusion surrounds the outer side of the second plate body.

[0023] In the above solution, by arranging the second plate body inside the convex portion, the area of the cover body can be increased, so that the external support structure can effectively support the battery cell through the cover body, thereby providing structural stability for the battery cell.

[0024] In some embodiments, the battery cell further includes a current collecting member for electrically connecting the first electrode tab of the electrode assembly and the end cap.

[0025] The convex portion protrudes from the cover body, so the convex portion will separate the cover body from the first pole ear in the thickness direction; if the end cover and the first pole ear are directly connected, the first pole ear can only be connected to the convex portion of the end cover, which will cause the area of the first pole ear that can directly transmit current to be limited by the convex portion. In the above scheme, by setting a current collecting component to connect the first pole ear and the end cover, the area of the first pole ear that can directly transmit current is no longer limited by the convex portion, and the current of the first pole ear can be collected into the end cover through the current collecting component. In this way, the current collecting component can reduce the difference in the conductive path between different areas of the first pole ear and the end cover, improve the uniformity of the current density of the first pole sheet, reduce the internal resistance, and improve the current capacity and charging efficiency of the battery cell.

[0026] In some embodiments, the current collecting component includes a first current collecting portion and a second current collecting portion connected to the first current collecting portion, the first current collecting portion is used to connect the first pole ear to electrically connect the current collecting component and the first pole ear; the second current collecting portion surrounds the outer side of the first current collecting portion, and the second current collecting portion is used to connect at least one of the protrusion and the second plate body to electrically connect the current collecting component and the end cover.

[0027] In some embodiments, the first current collecting portion is located between the second plate body and the first electrode tab and is welded to the first electrode tab, and the second current collecting portion is located between the first electrode tab and the protrusion and is welded to the protrusion.

[0028] In the above solution, when the end cover and the current collecting member are assembled, the laser may be applied to the surface of the protrusion facing away from the second current collecting portion, so as to weld the protrusion and the second current collecting portion from the outside.

[0029] In some embodiments, the current collecting member is in the shape of a flat plate.

[0030] In the above scheme, the flat current collecting member is easier to form. The flat current collecting member can be in contact with the first pole ear as a whole, thereby increasing the flow area and making the current collecting member support the first pole ear more evenly, reducing the risk of displacement and misalignment of the pole piece of the electrode assembly in the thickness direction.

[0031] In some embodiments, the protrusion is supported to the electrode assembly by a current collecting member.

[0032] In the above solution, the protrusion can support the electrode assembly through the first current collecting portion and the second current collecting portion to reduce the risk of the pole piece of the electrode assembly being offset or misaligned in the thickness direction.

[0033] In some embodiments, the current collecting component is located between the second plate body and the first electrode tab, and the protrusion surrounds the outer side of the current collecting component.

[0034] In the above solution, the convex portion does not overlap with the current collecting member in the thickness direction, which can reduce the space occupied by the end cover and the current collecting member in the thickness direction and improve the energy density.

[0035] In some embodiments, the second current collecting part is welded to the second plate body, and the first current collecting part is welded to the first pole lug. Welding can reduce the contact resistance between the second current collecting part and the second plate body and the contact resistance between the first current collecting part and the first pole lug, thereby improving the current carrying capacity.

[0036] In some embodiments, the first current collecting portion is protruding from the surface of the second current collecting portion facing the electrode assembly, and a second recessed portion is formed at a position of the current collecting member corresponding to the first current collecting portion, which is recessed from the surface of the second current collecting portion away from the electrode assembly in a direction facing the electrode assembly.

[0037] In the above solution, the first current collecting portion is protruding from the second current collecting portion and abutting against the first pole lug, thereby separating the first pole lug from the second current collecting portion. In this way, when welding the second plate body and the second current collecting portion, the heat transferred to the electrode assembly can be reduced, and the risk of burning the separator of the electrode assembly can be reduced. In this solution, the thickness of the first current collecting portion is reduced by providing the second recess, which can reduce the welding power required for welding the first current collecting portion to the first pole lug, reduce heat generation, and reduce the risk of burning other components.

[0038] In some embodiments, the protrusion and the first current collecting portion are both supported by the electrode assembly.

[0039] In the above solution, the first current collecting portion supports the middle area of the first pole ear, and the protrusion supports the edge area of the first pole ear, which can improve the uniformity of the force on the first pole ear and reduce the risk of displacement and misalignment of the pole piece of the electrode assembly in the thickness direction.

[0040] In some embodiments, the end cap is provided with a pressure relief mechanism connected to the second plate body. The pressure relief mechanism is configured to be actuated to release the internal pressure when the internal pressure of the battery cell reaches a threshold value. In the thickness direction, the first current collector is disposed opposite to the pressure relief mechanism, and there is a clearance between the first current collector and the pressure relief mechanism.

[0041] In the above solution, a clearance is provided between the first current collector and the pressure relief mechanism to reduce the risk of the first current collector pressing and damaging the pressure relief mechanism, and to ensure smooth exhaust when the pressure relief mechanism is actuated, thereby reducing the safety risk.

[0042] In some embodiments, the electrode assembly is of a wound structure, and the electrode assembly has a first through hole at the winding center. The first current collector is provided with a second through hole, and the second through hole is disposed opposite to the first through hole to communicate the first through hole with the clearance.

[0043] In the above solution, when the electrode assembly is out of control thermally, the high-temperature and high-pressure substances can quickly enter the clearance through the first through hole and the second through hole and act on the pressure relief mechanism, so that the pressure relief mechanism is actuated in time, reducing the safety risk.

[0044] In some embodiments, the first tab of the electrode assembly is electrically connected to the housing through the end cap.

[0045] In the above solution, the housing is connected to the first tab of the electrode assembly through the end cap so that the potential of the housing is substantially the same as the potential of the first tab. In this way, the housing itself can be used as the output terminal of the battery cell, thus eliminating a traditional electrode terminal and simplifying the structure of the battery cell.

[0046] In some embodiments, the housing further includes a side wall and a bottom wall connected to the side wall. The side wall extends in the thickness direction and surrounds the outer periphery of the electrode assembly, and the bottom wall is provided with an electrode lead-out hole. The battery cell further includes an electrode terminal installed in the electrode lead-out hole. The electrode terminal is electrically connected to the second tab of the electrode assembly. The first tab and the second tab have opposite polarities and are respectively located at both ends of the electrode assembly.

[0047] In the above solution, the bottom wall and the electrode terminal can be used as the two output terminals of the battery cell, which can simplify the structure of the battery cell and ensure the over-current capacity of the battery cell. The bottom wall and the electrode terminal are located at the same end of the battery cell. In this way, the current collecting component can be assembled on the same side of the battery cell, which can simplify the assembly process and improve the efficiency of assembling multiple battery cells into a group.

[0048] In some embodiments, the bottom wall and the side wall are integrally formed structures. This embodiment can eliminate the connection process between the bottom wall and the side wall and reduce the resistance between the bottom wall and the side wall.

[0049] In some embodiments, the first tab is a negative tab, and the base material of the housing is steel.

[0050] In the above solution, the housing is electrically connected to the negative electrode tab, that is, the housing is in a low potential state. The steel housing is not easily corroded by the electrolyte in the low potential state, so as to reduce the safety risk.

[0051] In some embodiments, the base material of the housing is the same as that of the end cap.

[0052] In the above solution, the base material of the housing is the same as that of the end cap, which is convenient for welding the housing and the end cap, improves the connection strength between the two, and ensures the sealing performance of the battery cell.

[0053] In some embodiments, the battery cell is a cylindrical battery cell.

[0054] In a second aspect, an embodiment of the present application provides a battery, including a plurality of battery cells according to any one of the first aspect.

[0055] In a third aspect, an embodiment of the present application provides an electrical device, including the battery in the second aspect, and the battery is used to provide electrical energy.

[0056] In a fourth aspect, an embodiment of the present application provides a manufacturing method of a battery cell, including:

[0057] Providing a housing with an opening;

[0058] Providing an electrode assembly and installing the electrode assembly into the housing;

[0059] Providing an end cap, the end cap includes a cap body and a convex portion, the cap body at least partially surrounds the outside of the convex portion, the convex portion protrudes from the inner surface of the cap body in the thickness direction of the end cap, and a first concave portion recessed relative to the outer surface of the cap body is formed at a position corresponding to the convex portion on the end cap;

[0060] Abutting the cap body against the housing, and then irradiating laser at the abutting portion of the cap body and the housing to weld the cap body to the housing, so that the end cap covers the opening;

[0061] Wherein, the convex portion protrudes from the inner surface of the cap body in the direction facing the electrode assembly and is used to block the laser when welding the cap body and the housing; the first concave portion is recessed from the outer surface of the cap body in the direction facing the electrode assembly and is used to release stress when welding the cap body and the housing.

[0062] In a fifth aspect, an embodiment of the present application provides a manufacturing system of a battery cell, including:

[0063] A first providing device for providing a housing with an opening;

[0064] A second providing device for providing an electrode assembly and installing the electrode assembly into the housing;

[0065] A third providing device for providing an end cover, the end cover including a cover body and a convex portion, the cover body at least partially surrounding the outside of the convex portion, the convex portion protruding from the inner surface of the cover body in the thickness direction of the end cover, and a first concave portion recessed relative to the outer surface of the cover body being formed at a position corresponding to the convex portion on the end cover;

[0066] An assembling device for abutting the cover body against the housing and then irradiating a laser at the abutting portion of the cover body and the housing to weld the cover body to the housing, thereby covering the end cover on the opening;

[0067] Wherein, the convex portion protrudes from the inner surface of the cover body in the direction facing the electrode assembly and is used to block the laser when welding the cover body and the housing; the first concave portion is recessed from the outer surface of the cover body in the direction facing the electrode assembly and is used to release stress when welding the cover body and the housing. Description of the Drawings

[0068] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0069] Figure 1 A schematic structural diagram of a vehicle provided by some embodiments of the present application;

[0070] Figure 2 An explosion schematic diagram of a battery provided by some embodiments of the present application;

[0071] Figure 3 For Figure 2 An explosion schematic diagram of the battery module shown;

[0072] Figure 4 A cross-sectional schematic diagram of a battery cell provided by some embodiments of the present application;

[0073] Figure 5 For Figure 4 An enlarged schematic diagram of the battery cell shown at the circular frame A;

[0074] Figure 6 For Figure 5 An enlarged schematic diagram of the battery cell shown at the square frame B;

[0075] Figure 7 A cross-sectional schematic diagram of a battery cell provided by other embodiments of the present application;

[0076] Figure 8 For Figure 7An enlarged schematic view of the battery cell shown at box C;

[0077] Figure 9 A flowchart showing a method for manufacturing a battery cell provided in some embodiments of the present application;

[0078] Figure 10 A schematic block diagram of a manufacturing system for a battery cell provided in some embodiments of the present application.

[0079] In the drawings, the drawings are not drawn to actual scale. Detailed Description of the Invention

[0080] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0081] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs; the terms used in the description of the present application in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the description and claims of the present application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of the present application or the above drawings are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship.

[0082] Referring to "embodiments" in the present application means that a specific feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0083] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", and "attached to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0084] In this application, the term "and / or" is merely a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, in this application, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0085] In the embodiments of this application, the same reference numerals represent the same components. And for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thickness, length, width, etc. of various components shown in the drawings of the embodiments of this application, as well as the overall thickness, length, width, etc. of the integrated device, are only exemplary descriptions and should not constitute any limitation to this application.

[0086] The term "a plurality of" as used in this application refers to two or more (including two).

[0087] In this application, the battery cell may include a lithium-ion secondary battery cell, a lithium-ion primary battery cell, a lithium-sulfur battery cell, a sodium-lithium-ion battery cell, a sodium-ion battery cell, a magnesium-ion battery cell, etc., and the embodiments of this application do not limit this. The battery cell can be in the shape of a cylinder, a flat body, a cuboid, or other shapes, and the embodiments of this application also do not limit this.

[0088] The battery mentioned in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide a higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack, etc. The battery generally includes a box for encapsulating one or more battery cells. The box can prevent liquids or other foreign objects from affecting the charging or discharging of the battery cells.

[0089] The battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The battery cell mainly operates by the movement of metal ions between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive current collector and a positive active material layer, and the positive active material layer is coated on the surface of the positive current collector; the positive current collector includes a positive current collecting portion and a positive electrode tab connected to the positive current collecting portion, the positive current collecting portion is coated with the positive active material layer, and the positive electrode tab is not coated with the positive active material layer. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material layer includes a positive active material, and the positive active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, etc. The negative electrode plate includes a negative current collector and a negative active material layer, and the negative active material layer is coated on the surface of the negative current collector; the negative current collector includes a negative current collecting portion and a negative electrode tab connected to the negative current collecting portion, the negative current collecting portion is coated with the negative active material layer, and the negative electrode tab is not coated with the negative active material layer. The material of the negative current collector can be copper, and the negative active material layer includes a negative active material, and the negative active material can be carbon or silicon, etc. The material of the separator can be PP (polypropylene) or PE (polyethylene), etc.

[0090] The battery cell further includes a housing and an end cap. The housing has an opening and is used to accommodate the electrode assembly, and the electrode assembly can be assembled into the housing through the opening of the housing. The end cap is used to cover the opening of the housing to achieve sealing.

[0091] The inventor uses laser welding to connect the end cap and the housing. Specifically, the inventor tries to abut the end cap and the housing together, and then irradiate laser at the abutting portion of the end cap and the housing. Under the action of the laser, the abutting portion of the end cap and the housing melts and is connected. However, the inventor finds that there may be a gap at the abutting portion of the end cap and the housing, and the laser may act on other components inside the housing after passing through the gap, leading to safety risks; and welding stress will be generated during welding, and the welding stress cannot be effectively released, resulting in the welded area being prone to deformation and cracking after welding, affecting the sealing performance.

[0092] In view of this, the embodiment of the present application provides a technical solution. By providing a convex portion on the end cap to block the laser when welding the end cap and the housing, the risk of laser burning other components is reduced; the embodiment of the present application also provides a first concave portion on the side of the convex portion facing away from the electrode assembly to reduce the strength of the convex portion. During the welding process, the convex portion can deform to release the welding stress, thereby reducing the risk of deformation and cracking of the welded area and improving the sealing performance.

[0093] The technical solution described in the embodiment of the present application is applicable to batteries and electrical devices using batteries.

[0094] The electrical device can be a vehicle, a mobile phone, a portable device, a laptop, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range extender vehicle, etc.; The spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.; The electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc.; The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator, a planer, etc. The embodiments of the present application do not impose special restrictions on the above electrical devices.

[0095] For the convenience of description, the following embodiments will take the electrical device as a vehicle as an example for description.

[0096] Figure 1 It is a schematic structural diagram of a vehicle provided by some embodiments of the present application.

[0097] As Figure 1 shown, a battery 2 is disposed inside the vehicle 1. The battery 2 can be disposed at the bottom, head or tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1. For example, the battery 2 can be used as the operating power source of the vehicle 1.

[0098] The vehicle 1 may further include a controller 3 and a motor 4. The controller 3 is used to control the battery 2 to supply power to the motor 4. For example, it is used for the working power requirements during the start, navigation and driving of the vehicle 1.

[0099] In some embodiments of the present application, the battery 2 can not only be used as the operating power source of the vehicle 1, but also be used as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0100] Figure 2 It is an explosion schematic diagram of a battery provided by some embodiments of the present application. As Figure 2 shown, the battery 2 includes a box body 5 and battery cells ( Figure 2 not shown), and the battery cells are accommodated in the box body 5.

[0101] The housing 5 is used to accommodate battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 can include a first housing portion 5a and a second housing portion 5b. The first housing portion 5a and the second housing portion 5b are covered with each other, and the first housing portion 5a and the second housing portion 5b together define an accommodation space 5c for accommodating battery cells. The second housing portion 5b can be a hollow structure with one end open, and the first housing portion 5a is a plate-like structure. The first housing portion 5a is covered on the open side of the second housing portion 5b to form the housing 5 with the accommodation space 5c; both the first housing portion 5a and the second housing portion 5b can also be hollow structures with one side open, and the open side of the first housing portion 5a is covered on the open side of the second housing portion 5b to form the housing 5 with the accommodation space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as a cylinder, a cuboid, etc.

[0102] To improve the sealing performance after the connection between the first housing portion 5a and the second housing portion 5b, a sealing member can also be provided between the first housing portion 5a and the second housing portion 5b, such as sealant, sealing ring, etc.

[0103] Assume that the first housing portion 5a is covered on the top of the second housing portion 5b. The first housing portion 5a can also be called the upper cover, and the second housing portion 5b can also be called the lower housing.

[0104] In the battery 2, there can be one or multiple battery cells. If there are multiple battery cells, the multiple battery cells can be connected in series, parallel, or in a combination of series and parallel (mixed connection). Mixed connection means that there are both series and parallel connections among the multiple battery cells. The multiple battery cells can be directly connected in series, parallel, or in a mixed connection together, and then the whole formed by the multiple battery cells is accommodated in the housing 5; of course, it can also be that multiple battery cells are first connected in series, parallel, or in a mixed connection to form battery modules 6, and then the multiple battery modules 6 are connected in series, parallel, or in a mixed connection to form a whole and are accommodated in the housing 5.

[0105] Figure 3 For Figure 2 The explosion schematic diagram of the battery module shown.

[0106] In some embodiments, as Figure 3 shown, there are multiple battery cells 7. The multiple battery cells 7 are first connected in series, parallel, or in a mixed connection to form battery modules 6. The multiple battery modules 6 are then connected in series, parallel, or in a mixed connection to form a whole and are accommodated in the housing.

[0107] The multiple battery cells 7 in the battery module 6 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of the multiple battery cells 7 in the battery module 6.

[0108] Figure 4 The cross-sectional schematic diagram of the battery cell provided in some embodiments of the present application; Figure 5for Figure 4 An enlarged schematic diagram of a battery cell at the circle A shown; Figure 6 for Figure 5 An enlarged schematic diagram of a battery cell at box B is shown.

[0109] like Figures 4 to 6 As shown, the battery cell 7 of the embodiment of the present application includes: a shell 20 having an opening 21; an electrode assembly 10, which is accommodated in the shell 20; and an end cap 30, including a cover body 31 and a convex portion 32, wherein the cover body 31 at least partially surrounds the outer side of the convex portion 32 and is used for laser welding with the shell 20, so that the end cap 30 covers the opening 21. In the thickness direction Z of the end cap 30, the convex portion 32 protrudes from the inner surface 31a of the cover body in the direction facing the electrode assembly 10, and is used to block the laser when welding the cover body 31 and the shell 20. A first concave portion 33 is formed on the end cap 30 at a position corresponding to the convex portion 32, which is concave from the outer surface 31b of the cover body in the direction facing the electrode assembly 10, and the first concave portion 33 is used to release stress when welding the cover body 31 and the shell 20.

[0110] The electrode assembly 10 includes a first electrode sheet, a second electrode sheet and a separator, wherein the separator is used to separate the first electrode sheet from the second electrode sheet. The first electrode sheet and the second electrode sheet have opposite polarities, in other words, one of the first electrode sheet and the second electrode sheet is a positive electrode sheet, and the other of the first electrode sheet and the second electrode sheet is a negative electrode sheet.

[0111] Optionally, the first pole piece, the second pole piece and the separator are all strip-shaped structures, and the first pole piece, the second pole piece and the separator are wound together to form a wound structure. The wound structure can be a cylindrical structure, a flat structure or a structure of other shapes.

[0112] From the appearance of the electrode assembly 10, the electrode assembly 10 includes a main body 11, a first pole ear 12 and a second pole ear 13, and the first pole ear 12 and the second pole ear 13 protrude from the main body 11. The first pole ear 12 is a portion of the first pole sheet that is not coated with an active material layer, and the second pole ear 13 is a portion of the second pole sheet that is not coated with an active material layer. Correspondingly, one of the first pole ear 12 and the second pole ear 13 is a positive polarity pole ear, and the other is a negative polarity pole ear.

[0113] The first electrode tab 12 and the second electrode tab 13 may extend from the same side of the main body 11 , or may extend from opposite sides respectively.

[0114] Exemplarily, the first pole tab 12 and the second pole tab 13 are respectively arranged on both sides of the main body 11, in other words, the first pole tab 12 and the second pole tab 13 are respectively arranged at both ends of the electrode assembly 10. Optionally, the first pole tab 12 is located at one end of the electrode assembly 10 facing the end cap 30, and the second pole tab 13 is located at one end of the electrode assembly 10 away from the end cap 30.

[0115] Optionally, the first pole lug 12 is wound around the central axis of the electrode assembly 10 for multiple turns. In other words, the first pole lug 12 includes multiple turns of pole lug layers. After winding, the first pole lug 12 is generally cylindrical, and a gap is left between two adjacent turns of pole lug layers. The embodiment of the present application can process the first pole lug 12 to reduce the gap between the pole lug layers, so as to facilitate the connection of the first pole lug 12 with other conductive structures. For example, the embodiment of the present application can flatten the first pole lug 12 so that the end area of the first pole lug 12 away from the main body 11 is gathered and gathered together; the flattening process forms a dense end face at the end of the first pole lug 12 away from the main body 11, reduces the gap between the pole lug layers, and facilitates the connection of the first pole lug 12 with other conductive structures. Alternatively, the embodiment of the present application can also fill the conductive material between two adjacent turns of pole lug layers to reduce the gap between the pole lug layers.

[0116] Optionally, the second pole tab 13 is wound around the central axis of the electrode assembly 10 for multiple turns, and the second pole tab 13 includes multiple turns of pole tab layers. Exemplarily, the second pole tab 13 is also flattened to reduce the gap between the pole tab layers of the second pole tab 13.

[0117] The shell 20 is a hollow structure with one side open. The end cover 30 covers the opening of the shell 20 and forms a sealed connection to form a receiving cavity for receiving the electrode assembly 10 and the electrolyte.

[0118] The shell 20 is a hollow structure, and a space for accommodating the electrode assembly 10 is formed inside the shell 20. The shell 20 can be in various shapes, such as a cylinder, a cuboid, etc. The shape of the shell 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cylindrical structure, a cylindrical shell can be selected; if the electrode assembly 10 is a cuboid structure, a cuboid shell can be selected.

[0119] The shell 20 may be positively charged, negatively charged, or uncharged. When the shell 20 needs to be charged, the shell 20 may be directly connected to the tab of the electrode assembly 10 or may be electrically connected to the tab through other conductive components.

[0120] The end cap 30 and the housing 20 are connected by welding, and the end cap 30 and the housing 20 may have the same polarity. For example, when the housing 20 needs to be positively charged, the end cap 30 may be used to electrically connect the housing 20 to the positive polarity pole lug; when the housing 20 needs to be negatively charged, the end cap 30 may be used to electrically connect the housing 20 to the negative polarity pole lug. Of course, the housing 20 may also be connected to the pole lug through other conductive structures, which is not limited in this embodiment.

[0121] The housing 20 and the end cover 30 may be made of the same material or different materials, as long as they can be connected by laser welding.

[0122] The end cap 30 can be electrically connected to the electrode assembly 10 or can be insulated from the electrode assembly 10. Optionally, the end cap 30 is electrically connected to the first tab 12. Of course, the end cap 30 can be directly electrically connected to the first tab 12 or can be electrically connected to the first tab 12 through other components.

[0123] The cover body 31 has a plate-like structure and has an inner surface and an outer surface oppositely arranged along its own thickness direction. The inner surface 31a of the cover body faces the electrode assembly 10. Optionally, both the inner surface 31a and the outer surface 31b of the cover body are flat and parallel to each other.

[0124] The convex portion 32 protrudes from the inner surface 31a of the cover body in the direction facing the electrode assembly 10, so that at least a part of the convex portion 32 protrudes from the inner surface 31a of the cover body. In this embodiment, there is no limitation on the degree to which the convex portion 32 protrudes from the inner surface 31a of the cover body.

[0125] The position of the first concave portion 33 corresponds to the position of the convex portion 32. The first concave portion 33 is recessed from the outer surface 31b of the cover body in the direction facing the electrode assembly 10. The first concave portion 33 can reduce the strength of the convex portion 32, so that the area of the end cap 30 corresponding to the convex portion 32 has better elasticity.

[0126] The cover body 31 can entirely surround the outside of the convex portion 32 or only a part of it can surround the outside of the convex portion 32. For example, the convex portion 32 can be an annular structure, and the cover body 31 also has a part surrounded by the convex portion 32.

[0127] During laser welding, the laser acts on the abutting portion of the housing 20 and the cover body 31 to weld the housing 20 and the cover body 31. Due to the fitting error, there may be a small gap at the abutting portion of the housing 20 and the cover body 31, and the laser is likely to pass through these gaps and irradiate the inside of the housing 20, thereby causing the risk of other components (such as the electrode assembly 10) inside the housing 20 being burned. Since the convex portion 32 protrudes from the inner surface 31a of the cover body, when the laser enters the housing 20 along the gap at the abutting portion, the convex portion 32 can block the laser and reduce the risk of other components being burned by the laser.

[0128] When welding the cover body 31 and the housing 20, welding stress will be generated on the cover body 31, and the welding stress will be transmitted to the convex portion 32. In the embodiment of the present application, by further providing the first concave portion 33 on the side of the convex portion 32 facing away from the electrode assembly 10 to reduce the strength of the convex portion 32, during the welding process, the convex portion 32 can deform to release the welding stress, thereby reducing the risk of deformation and cracking in the welding area and improving the sealing performance.

[0129] In some embodiments, the first tab 12 of the electrode assembly 10 is electrically connected to the housing 20 through the end cap 30.

[0130] The end cap 30 can be directly connected to the first tab 12. For example, the end cap 30 can be directly welded to the first tab 12 to achieve the electrical connection between the end cap 30 and the first tab 12. Alternatively, the end cap 30 can also be indirectly connected to the first tab 12 through other conductive structures (such as the current collector member described later). It can be understood that in this embodiment, either the convex portion 32 or the cover body 31 can be connected to the conductive structure.

[0131] In this embodiment, the housing 20 is connected to the first tab 12 of the electrode assembly 10 through the end cap 30, so that the potential of the housing 20 is substantially the same as that of the first tab 12. In this way, the housing 20 itself can serve as the output pole of the battery cell 7, thus eliminating a traditional electrode terminal and simplifying the structure of the battery cell 7.

[0132] When multiple battery cells 7 are assembled into a group, the housing 20 can be electrically connected to the busbar component, which can not only increase the current-carrying area but also make the structural design of the busbar component more flexible.

[0133] In some embodiments, the housing 20 further includes a side wall 22 and a bottom wall 23 connected to the side wall 22. The side wall 22 extends along the thickness direction Z and surrounds the outer periphery of the electrode assembly 10. The bottom wall 23 is provided with an electrode lead-out hole 231. The battery cell 7 further includes an electrode terminal 40 installed in the electrode lead-out hole 231. The electrode terminal 40 is electrically connected to the second tab 13 of the electrode assembly 10. The first tab 12 and the second tab 13 have opposite polarities and are respectively located at both ends of the electrode assembly 10.

[0134] The side wall 22 and the bottom wall 23 can be integrally formed structures, that is, the housing 20 is an integrally formed member. Of course, the side wall 22 and the bottom wall 23 can also be two separately provided members, and then connected together by welding, riveting, bonding, etc.

[0135] One end of the side wall 22 forms an opening 21 of the housing 20, and the bottom wall 23 is connected to the other end of the side wall 22 away from the opening 21. The side wall 22 is a cylindrical structure. For example, the side wall 22 can be a cylindrical tube or a square tube; the bottom wall 23 is a plate-like structure, and its shape corresponds to the shape of the side wall 22.

[0136] The second tab 13 can be directly electrically connected to the electrode terminal 40, or can be indirectly electrically connected to the electrode terminal 40 through other conductive structures.

[0137] The electrode terminal 40 is insulatingly disposed on the bottom wall 23. The electrode terminal 40 and the bottom wall 23 can have different polarities, and the electrode terminal 40 and the bottom wall 23 can respectively serve as the two output poles of the battery cell 7. Optionally, the battery cell further includes an insulating member, and at least a part of the insulating member is located between the bottom wall 23 and the electrode terminal 40 to insulatively separate the bottom wall 23 and the electrode terminal 40.

[0138] When the first tab 12 is a negative tab and the second tab 13 is a positive tab, the bottom wall 23 is the negative output pole of the battery cell 7, and the electrode terminal 40 is the positive output pole of the battery cell 7. When the first tab 12 is a positive tab and the second tab 13 is a negative tab, the bottom wall 23 is the positive output pole of the battery cell 7, and the electrode terminal 40 is the negative output pole of the battery cell 7.

[0139] The electrode terminal 40 is fixed to the bottom wall 23. The electrode terminal 40 can be integrally fixed outside the bottom wall 23, or can extend into the interior of the housing 20 through the electrode lead-out hole 231.

[0140] The first tab 12 is located at one end of the electrode assembly 10 facing the end cap 30 to facilitate electrical connection between the end cap 30 and the first tab 12; correspondingly, the second tab 13 is located at one end of the electrode assembly 10 facing the bottom wall 23 to facilitate electrical connection between the electrode terminal 40 and the second tab 13. In the embodiment of the present application, the first tab 12 and the second tab 13 are disposed at both ends of the electrode assembly 10, which can reduce the risk of conduction between the first tab 12 and the second tab 13 and increase the current-carrying area of the first tab 12 and the current-carrying area of the second tab 13.

[0141] In this embodiment, the bottom wall 23 and the electrode terminal 40 can serve as the two output poles of the battery cell 7, which can simplify the structure of the battery cell 7 and ensure the current-carrying capacity of the battery cell 7. The bottom wall 23 and the electrode terminal 40 are located at the same end of the battery cell 7. In this way, the busbar component can be assembled on the same side of the battery cell 7, which can simplify the assembly process and improve the efficiency of assembling multiple battery cells 7 into a group.

[0142] In some embodiments, the bottom wall 23 and the side wall 22 are integrally formed structures. This embodiment can eliminate the connection process between the bottom wall 23 and the side wall 22 and reduce the resistance between the two. For example, the housing 20 can be formed by a stretching process.

[0143] The electrode lead-out hole 231 in the embodiment of the present application is made after the housing 20 is stretch-formed.

[0144] The inventors have tried to roll the open end of the housing so that the open end of the housing is turned inward to form a flanging structure, and the flanging structure presses against the end cap to achieve the fixation of the end cap. The inventors installed the electrode terminals on the end cap, and used the flanging structure and the electrode terminals as the two output poles of the battery cell. However, the larger the size of the flanging structure, the higher the risk of curling and wrinkling after forming; if the flanging structure has curling and wrinkling, the surface of the flanging structure will be uneven, and when the flanging structure is welded to the busbar component, there will be problems with poor welding. Therefore, the size of the flanging structure is relatively limited, resulting in insufficient current-carrying capacity of the battery cell.

[0145] In this embodiment, an electrode lead-out hole 231 for installing the electrode terminal 40 is formed on the bottom wall 23 by means of an opening process, so as to arrange the positive output pole and the negative output pole at one end of the battery cell 7 away from the opening 21; the bottom wall 23 is formed during the forming process of the housing 20, and the flatness of the bottom wall 23 can be ensured after the electrode lead-out hole 231 is opened, and the connection strength between the bottom wall 23 and the busbar component can be ensured. At the same time, the flatness of the bottom wall 23 is not restricted by its own size, so the bottom wall 23 can have a larger size, thereby improving the current-carrying capacity of the battery cell 7.

[0146] In some embodiments, the first tab 12 is a negative tab, and the base material of the housing 20 is steel.

[0147] The housing 20 is electrically connected to the negative tab, that is, the housing 20 is in a low-potential state. The steel housing 20 is not easily corroded by the electrolyte in the low-potential state, so as to reduce the safety risk.

[0148] In some embodiments, the housing 20 further includes a protective layer provided on the surface of the base material. Optionally, the protective layer is a nickel layer plated on the surface of the base material.

[0149] In some embodiments, the base material of the housing 20 and the base material of the end cap 30 are the same. Optionally, the base materials of the housing 20 and the end cap 30 are both steel.

[0150] In this embodiment, the base materials of the housing 20 and the end cap 30 are the same, which can facilitate the welding of the housing 20 and the end cap 30, improve the connection strength between the two, and ensure the sealing performance of the battery cell 7.

[0151] In some embodiments, the battery cell 7 is a cylindrical battery cell. Correspondingly, the electrode assembly 10 is of a cylindrical structure, and the housing 20 is a cylindrical hollow structure.

[0152] In some embodiments, the side wall 22 of the housing 20 and the cover body 31 are arranged along the thickness direction Z of the end cover 30. When welding the side wall 22 and the cover body 31, the laser acts on the abutting portion of the side wall 22 and the cover body 31, and at least part of the cover body 31 and at least part of the side wall 22 are melted and connected together.

[0153] In some embodiments, the housing 20 has an outer end face 24 at the open end, and the outer end face 24 is disposed around the opening 21 of the housing 20. The outer end face 24 is the end face of the side wall 22 at the end away from the bottom wall 23. Optionally, the outer end face 24 is a flat surface.

[0154] The outer end face 24 of the housing 20 forms a certain angle with the thickness direction Z of the end cover 30. Optionally, the outer end face 24 of the housing 20 is perpendicular to the thickness direction Z of the end cover 30.

[0155] The side wall 22 of the housing 20 has an inner surface and an outer surface which are oppositely arranged. The inner surface 221 of the side wall faces the electrode assembly 10. Both the inner surface 221 and the outer surface 222 of the side wall are annular surfaces. The outer end face 24 connects the inner surface 221 and the outer surface 222 of the side wall. Optionally, the outer end face 24 is perpendicular to the inner surface 221 and the outer surface 222 of the side wall.

[0156] The inner surface 31a of the cover body can abut against the outer end face 24. Of course, in alternative embodiments, it can also abut against other surfaces of the housing 20. For example, the side wall 22 further has a stepped surface (not shown) that is recessed inward relative to the outer end face 24 and connected to the inner surface 221 of the side wall, and the stepped surface can be in abutting cooperation with the inner surface 31a of the cover body.

[0157] In some embodiments, the housing 20 has an outer end face 24 surrounding the opening 21, and the outer end face 24 of the housing 20 is welded to the inner surface 31a of the cover body so that the housing 20 and the cover body 31 are connected as a whole.

[0158] The inner surface 31a of the cover body is arranged parallel to the outer end face 24. The inner surface 31a of the cover body and the outer end face 24 are fitted in the thickness direction Z. When welding, the laser irradiates at the junction of the outer end face 24 and the inner surface 31a of the cover body.

[0159] After welding, at least part of the inner surface 31a of the cover body and at least part of the outer end face 24 are melted and connected together.

[0160] The outer end face 24 is at the outermost end of the housing 20. In this embodiment, the inner surface 31a of the cover body is abutted against the outer end face 24, which can reduce the internal space of the housing 20 occupied by the cover body 31. When assembling the end cover 30 and the housing 20, the outer end face 24 can play a role in limiting in the thickness direction Z of the end cover 30.

[0161] In some embodiments, in the thickness direction Z, the bottom surface 331 of the first recess 33 is closer to the electrode assembly 10 as a whole compared to the inner surface 31a of the cover body.

[0162] The first recess 33 and the convex portion 32 can be formed by stamping the end cover 30.

[0163] The greater the depth of the first recess 33 in the thickness direction Z, the greater the degree to which the convex portion 32 protrudes from the inner surface 31a of the cover body.

[0164] The embodiments of the present application can ensure the degree to which the convex portion 32 protrudes from the inner surface 31a of the cover body to more effectively block the laser and reduce the risk of laser burning the electrode assembly 10. At the same time, on the premise of ensuring the protruding degree of the convex portion 32, the embodiments of the present application further ensure the degree of depression of the first recess 33 so that the convex portion 32 can release the welding stress through deformation.

[0165] In some embodiments, the convex portion 32 has a top end surface 321 and an outer side surface facing the side wall 22, and the outer side surface is an annular surface surrounding the top end surface 321. The top end surface 321 is the surface of the convex portion 32 facing the electrode assembly 10, and the outer side surface faces the side wall 22 and is used to block the laser. Optionally, a gap may be provided between the outer side surface and the inner surface 221 of the side wall, and this gap can facilitate the insertion of the convex portion 32 into the housing 20 through the opening 21 of the housing 20.

[0166] The outer side surface may also have a portion inclined with respect to the inner surface 221 of the side wall, and the inclined portion can play a guiding role to guide the convex portion 32 into the housing 20. Of course, alternatively, the guiding function of the outer side surface can be omitted. For example, the outer side surface can be parallel to the inner surface 221 of the side wall.

[0167] The top end surface 321 of the convex portion 32 can be a flat surface or a curved surface. Optionally, the top end surface 321 of the convex portion 32 is a flat surface.

[0168] In some embodiments, the housing 20 includes a side wall 22, and the side wall 22 extends in the thickness direction Z and surrounds the outer periphery of the electrode assembly 10. The convex portion 32 includes a blocking surface 323 facing the side wall 22, and the blocking surface 323 is parallel to the thickness direction Z and extends from the inner surface 31a of the cover body in the direction facing the electrode assembly 10.

[0169] The blocking surface 323 can be directly connected to the inner surface 31a of the cover body or can be indirectly connected to the inner surface 31a of the cover body through other surfaces.

[0170] The outer side surface of the convex portion 32 includes the blocking surface 323, and the blocking surface 323 can be directly connected to the top end surface 321 of the convex portion 32 or can be indirectly connected to the top end surface 321 through other surfaces.

[0171] When welding the side wall 22 and the cover body 31, the laser irradiates on the blocking surface 323 through the gap between the outer end surface 24 and the inner surface 31a of the cover body. The blocking surface 323 is arranged parallel to the side wall 22, and the two can limit the reflection direction of the laser, and to a certain extent, reduce the risk of the laser burning other components inside the housing 20 after reflection.

[0172] In some embodiments, the blocking surface 323 is perpendicular to the inner surface 31a of the cover body, so that the blocking surface 323 is perpendicular to the irradiation direction of the laser.

[0173] When welding the side wall 22 and the cover body 31, the laser acts at the junction of the outer end surface 24 and the inner surface 31a of the cover body, and the irradiation direction of the laser is parallel to the inner surface 31a of the cover body. When the laser irradiates on the blocking surface 323 through the gap between the outer end surface 24 and the inner surface 31a of the cover body, the incident angle of the laser is 0°, so that the laser can be reflected to the junction of the outer end surface 24 and the inner surface 31a of the cover body, so as to reduce the risk of the laser burning other components after reflecting inside the housing 20.

[0174] In some embodiments, the convex portion 32 further includes a guiding surface 322 facing the side wall 22. The guiding surface 322 is connected to the end of the blocking surface 323 far from the inner surface 31a of the cover body. The guiding surface 322 is inclined away from the side wall 22 compared with the blocking surface 323 to guide the convex portion 32 to be inserted into the housing 20.

[0175] The outer side surface of the convex portion 32 facing the side wall 22 includes a guiding surface 322 and a blocking surface 323. The guiding surface 322 can be directly connected to the top end surface 321, or can be indirectly connected to the top end surface 321 through other surfaces. The guiding surface 322 surrounds one week.

[0176] The guiding surface 322 is spaced from the inner surface 221 of the side wall. In the direction of the end cover 30 pointing to the electrode assembly 10, the distance between the guiding surface 322 and the inner surface 221 of the side wall gradually increases. Among them, the direction of the end cover 30 pointing to the electrode assembly 10 is parallel to the thickness direction Z; the distance between the guiding surface 322 and the inner surface 221 of the side wall refers to: the dimension of the gap between the guiding surface 322 and the inner surface 221 of the side wall in the normal direction of the inner surface 221 of the side wall.

[0177] In this application, by providing the inclined guiding surface 322 on the convex portion 32, the convex portion 32 can be guided to be inserted into the housing 20 when assembling the end cover 30 and the housing 20, so as to simplify the assembly process and improve the assembly efficiency.

[0178] In some embodiments, at least part of the guiding surface 322 can be formed by rounding the convex portion 32.

[0179] In some embodiments, a connection portion 324 is formed between the top surface 321 of the protrusion 32 and the bottom surface 331 of the first recess 33 , and the connection portion 324 is used for welding to the first electrode tab 12 of the electrode assembly 10 .

[0180] During assembly, the top end surface 321 of the protrusion 32 can be first abutted against the first pole ear 12, and then the bottom surface 331 of the first recess 33 can be irradiated with a laser. The laser melts and connects a portion of the connecting portion 324 and a portion of the first pole ear 12, thereby realizing the welding of the connecting portion 324 and the first pole ear 12.

[0181] In this embodiment, the connection portion 324 of the protrusion 32 can be directly welded to the first pole tab 12 without other transition components, thereby simplifying the structure of the battery cell 7. In this embodiment, the thickness of the connection portion 324 is reduced by providing the first recess 33, which can reduce the welding power required for welding the connection portion 324 to the first pole tab 12, reduce heat generation, and reduce the risk of other components being burned.

[0182] In some examples, the cover body 31 includes a first plate 311 and a second plate 312 , the first plate 311 surrounds the outer side of the protrusion 32 and is used for laser welding with the housing 20 , and the protrusion 32 surrounds the outer side of the second plate 312 .

[0183] The first plate body 311 and the second plate body 312 are both substantially flat plate structures. The first plate body 311 and the protrusion 32 are both annular.

[0184] The convex portion 32 is used to block the laser, so the distance between the convex portion 32 and the side wall 22 is small, which causes the overall area of the first plate 311 to be small. When the battery cell is installed in the electrical device, since the first recess 33 is formed on the side of the convex portion 32 facing away from the electrode assembly 10, the support structure of the electrical device generally cannot support the battery cell 7 through the convex portion 32. If the cover body 31 only includes the first plate body 311, then when the battery cell is installed in the electrical device, the support structure of the electrical device can only support the entire battery cell 7 through the first plate body 311, which will cause the first plate body 311 to be subjected to greater force and easily deformed, resulting in insufficient stability of the battery cell 7. The embodiment of the present application increases the area of the cover body 31 by arranging the second plate body 312 on the inner side of the convex portion 32, so that the external support structure can effectively support the battery cell 7 through the cover body 31, thereby improving the structural stability of the battery cell 7.

[0185] In some embodiments, the battery cell 7 further includes a current collecting member 50 , which is used to electrically connect the first electrode tab 12 of the electrode assembly 10 and the end cap 30 .

[0186] The current collecting member 50 can connect the end cap 30 to the first electrode tab 12 , thereby making the polarity of the housing 20 and the first electrode tab 12 the same.

[0187] The current collector member 50 can be connected to the first tab 12 by welding, bonding or other means to achieve electrical connection with the first tab 12. The current collector member 50 can be connected to the end cap 30 by welding, bonding or other means to achieve electrical connection with the end cap 30.

[0188] The current collector member 50 can be connected to the convex portion 32 or the second plate body 312.

[0189] The second plate body 312 and the first plate body 311 are respectively arranged on the inner and outer sides of the convex portion 32. The first plate body 311 is used for welding with the housing 20. The external support structure can support the battery cell 7 through the first plate body 311 and the second plate body 312 to improve the structural stability of the battery cell 7.

[0190] The convex portion 32 protrudes from the cover body 31, so the convex portion 32 will separate the cover body 31 and the first tab 12 in the thickness direction Z. If the end cap 30 and the first tab 12 are directly connected, then the first tab 12 can only be connected to the convex portion 32 of the end cap 30. If the convex portion 32 and the first tab 12 are directly connected, then only the part of the first tab 12 opposite to the convex portion 32 can be directly connected to the convex portion 32, resulting in the area of the first tab 12 that can directly transmit current being restricted by the convex portion 32, leading to insufficient current-carrying area between the convex portion 32 and the first tab 12. The current on the part of the first tab 12 opposite to the second plate body 312 in the thickness direction Z needs to first flow to the part of the first tab 12 welded to the convex portion 32 and then to the convex portion 32, which will cause a large difference in the conduction paths between different regions of the first tab 12 and the end cap 30, affecting the overcurrent capacity and charging efficiency of the battery cell 7.

[0191] In the embodiment of the present application, by providing the current collector member 50 to connect the first tab 12 and the end cap 30, the area of the first tab 12 that can directly transmit current is no longer restricted by the convex portion 32. The current of the first tab 12 can flow into the end cap 30 via the current collector member 50. In this way, the current collector member 50 can reduce the difference in the conduction paths between different regions of the first tab 12 and the end cap 30, improve the uniformity of the current density of the first electrode plate, reduce the internal resistance, and improve the overcurrent capacity and charging efficiency of the battery cell 7.

[0192] In some embodiments, the current collector member 50 includes a first current collecting portion 51 and a second current collecting portion 52 connected to the first current collecting portion 51. The first current collecting portion 51 is used for connecting the first tab 12 to electrically connect the current collector member 50 and the first tab 12. The second current collecting portion 52 surrounds the outside of the first current collecting portion 51. The second current collecting portion 52 is used for connecting at least one of the convex portion 32 and the second plate body 312 to electrically connect the current collector member 50 and the end cap 30.

[0193] The first current collector portion 51 can be connected to the first tab 12 by welding, bonding or other means, and the second current collector portion 52 can be connected to the end cap 30 by welding, bonding or other means.

[0194] In some embodiments, the first current collector portion 51 is located between the second plate body 312 and the first tab 12 and is welded to the first tab 12, and the second current collector portion 52 is located between the first tab 12 and the convex portion 32 and is welded to the convex portion 32.

[0195] When assembling the end cap 30 and the current collector member 50, the laser can act on the surface of the convex portion 32 facing away from the second current collector portion 52 to weld the convex portion 32 and the second current collector portion 52 from the outside. In this embodiment, by providing the first recess 33, the thickness of the connecting portion 324 of the convex portion 32 is reduced, so that the welding power required for welding the convex portion 32 and the second current collector portion 52 can be reduced, the heat generation can be reduced, and the risk of burning other components (such as the separator) can be reduced.

[0196] Optionally, the surface of the second current collector portion 52 facing away from the convex portion 32 abuts against the first tab 12. In this way, the convex portion 32 supports the first tab 12 through the second current collector portion 52. The surface of the first current collector portion 51 facing the first tab 12 abuts against and is welded to the first tab 12.

[0197] In some embodiments, the current collector member 50 is flat.

[0198] The flat current collector member 50 is easier to form. The flat current collector member 50 can be in contact with the first tab 12 as a whole, thereby increasing the current-carrying area and supporting the first tab 12 more evenly by the current collector member 50, reducing the risk of the electrode sheet of the electrode assembly 10 shifting and misaligning in the thickness direction Z.

[0199] In the flat current collector member 50, the portion of the current collector member 50 abutting against the convex portion 32 is the second current collector portion 52, and the portion of the current collector member 50 surrounded by the second current collector portion 52 is the first current collector portion 51.

[0200] In some embodiments, the convex portion 32 is supported by the current collector member 50 on the electrode assembly 10.

[0201] The convex portion 32 of this embodiment can support the electrode assembly 10 through the first current collector portion 51 and the second current collector portion 52, so as to reduce the risk of the electrode sheet of the electrode assembly 10 shifting and misaligning in the thickness direction Z.

[0202] Figure 7 It is a schematic cross-sectional view of a battery cell provided in other embodiments of the present application; Figure 8 For Figure 7 An enlarged schematic view of the battery cell shown at box C.

[0203] AsFigure 7 and Figure 8 As shown in Figure 8 , in some embodiments, the current collector member 50 is located between the second plate body 312 and the first tab 12, and the convex portion 32 surrounds the outside of the current collector member 50.

[0204] In this embodiment, the convex portion 32 does not overlap with the current collector member 50 in the thickness direction Z, which can reduce the space occupied by the end cap 30 and the current collector member 50 in the thickness direction Z and improve the energy density.

[0205] In some embodiments, the second current collecting portion 52 is welded to the second plate body 312, and the first current collecting portion 51 is welded to the first tab 12.

[0206] The second current collecting portion 52 directly abuts against the second plate body 312 and is connected to the second plate body 312 by laser welding. Exemplarily, the laser can act on the second plate body 312 to weld the second plate body 312 and the second current collecting portion 52 from the outside.

[0207] Welding can reduce the contact resistance between the second current collecting portion 52 and the second plate body 312 and the contact resistance between the first current collecting portion 51 and the first tab 12, and improve the overcurrent capacity.

[0208] In some embodiments, the first current collecting portion 51 protrudes from the surface of the second current collecting portion 52 facing the electrode assembly 10, and a second concave portion 53 is formed at a position corresponding to the first current collecting portion 51 on the current collector member 50, which is recessed from the surface of the second current collecting portion 52 facing away from the electrode assembly 10 in the direction facing the electrode assembly 10.

[0209] The first current collecting portion 51 protrudes from the second current collecting portion 52 and abuts against the first tab 12, thereby spacing the first tab 12 and the second current collecting portion 52 apart. In this way, when welding the second plate body 312 and the second current collecting portion 52, the heat transferred to the electrode assembly 10 can be reduced, and the risk of the separator of the electrode assembly 10 being burned is reduced.

[0210] In this embodiment, the second concave portion 53 is provided to reduce the thickness of the first current collecting portion 51, which can reduce the welding power required for welding the first current collecting portion 51 and the first tab 12, reduce heat generation, and reduce the risk of other components (such as the separator) being burned.

[0211] In some embodiments, the convex portion 32 and the first current collecting portion 51 support the electrode assembly 10.

[0212] The first current collecting portion 51 supports the middle region of the first tab 12, and the convex portion 32 supports the edge region of the first tab 12, which can improve the uniformity of the force on the first tab 12 and reduce the risk of the electrode plate of the electrode assembly 10 shifting and misaligning in the thickness direction Z.

[0213] In some embodiments, the end cap 30 is provided with a pressure relief mechanism 34 connected to the second plate body 312. The pressure relief mechanism 34 is configured to be actuated to release the internal pressure when the internal pressure of the battery cell 7 reaches a threshold value. In the thickness direction Z, the first current collector portion 51 is disposed opposite to the pressure relief mechanism 34, and there is a clearance gap G between the first current collector portion 51 and the pressure relief mechanism 34.

[0214] The pressure relief mechanism 34 refers to an element or component that is actuated to release the internal pressure when the internal pressure of the battery cell 7 reaches a predetermined threshold value. This threshold design varies according to different design requirements. The threshold value may depend on one or several of the materials of the positive electrode plate, negative electrode plate, electrolyte, and separator in the battery cell 7. The pressure relief mechanism 34 may be in the form of, for example, an explosion-proof valve, a gas valve, a pressure relief valve, or a safety valve, and may specifically adopt a pressure-sensitive element or structure, that is, when the internal pressure of the battery cell 7 reaches a predetermined threshold value, the pressure relief mechanism 34 performs an action or a weak structure provided in the pressure relief mechanism 34 ruptures, thereby forming an opening or channel for the release of the internal pressure or temperature.

[0215] The "actuation" mentioned in the present application means that the pressure relief mechanism 34 generates an action or is activated to a certain state, so that the internal pressure of the battery cell 7 can be released. The actions generated by the pressure relief mechanism 34 may include, but are not limited to: at least a part of the pressure relief mechanism 34 rupturing, breaking, being torn, or opening, etc. When the pressure relief mechanism 34 is actuated, the high-temperature and high-pressure substances inside the battery cell 7 will be discharged outward from the actuated part as emissions. In this way, the battery cell 7 can be depressurized under a controllable pressure, thereby avoiding potential more serious accidents.

[0216] The emissions from the battery cell 7 mentioned in the present application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of the separator, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0217] The pressure relief mechanism 34 is a part of the end cap 30, and it may be integrally formed with the second plate body 312. Alternatively, the pressure relief mechanism 34 and the second plate body 312 may also be two separately provided components, and the two are connected by welding, riveting, bonding, or other means.

[0218] The first current collector portion 51 and the pressure relief mechanism 34 at least partially overlap in the thickness direction Z. Therefore, if the first current collector portion 51 contacts the pressure relief mechanism 34, then the first current collector portion 51 may block the discharge of the high-temperature and high-pressure substances when the pressure relief mechanism 34 is actuated, leading to safety risks. In addition, if the first current collector portion 51 and the pressure relief mechanism 34 contact, when the battery cell 7 vibrates, the first current collector portion 51 is likely to crush the pressure relief mechanism 34, resulting in the failure of the pressure relief mechanism 34.

[0219] In this embodiment, a clearance gap G is provided between the first current collector portion 51 and the pressure relief mechanism 34 to reduce the risk of the first current collector portion 51 damaging the pressure relief mechanism 34, and to ensure smooth exhaust when the pressure relief mechanism 34 is actuated, thereby reducing the safety risk.

[0220] In some embodiments, the present application provides a second recess 53 on the side of the first current collector portion 51 facing the end cap 30 to space the first current collector portion 51 from the pressure relief mechanism 34 and form the clearance gap G. In other embodiments, for the flat current collector member 50, the convex portion 32 supports the first current collector portion 51 through the second current collector portion 52 to space the first current collector portion 51 from the pressure relief mechanism 34 and form the clearance gap G.

[0221] In some embodiments, the end cap 30 forms a third recess 341 at a position corresponding to the pressure relief mechanism 34, which is recessed from the outer surface of the second plate body 312 in the direction facing the electrode assembly 10. A groove is provided at the bottom of the third recess 341. When the internal pressure of the battery cell 7 reaches a threshold value, the pressure relief mechanism 34 ruptures along the groove to release the internal pressure.

[0222] In some embodiments, the second plate body 312 is an annular flat plate surrounding the outside of the pressure relief mechanism 34.

[0223] In some embodiments, the electrode assembly 10 has a wound structure, and the electrode assembly 10 has a first through hole 14 at the winding center. The first current collector portion 51 is provided with a second through hole 511, and the second through hole 511 is disposed opposite to the first through hole 14 to communicate the first through hole 14 with the clearance gap G.

[0224] In the thickness direction Z, the first through hole 14 and the second through hole 511 at least partially overlap.

[0225] When the electrode assembly 10 experiences thermal runaway, the high-temperature and high-pressure substances can quickly enter the clearance gap G through the first through hole 14 and the second through hole 511 and act on the pressure relief mechanism 34, thereby causing the pressure relief mechanism 34 to be actuated in a timely manner and reducing the safety risk.

[0226] Figure 9 It is a schematic flow chart of the manufacturing method of the battery cell provided in some embodiments of the present application.

[0227] As Figure 9 shown, the manufacturing method of the battery cell according to the embodiment of the present application includes:

[0228] S100. Provide a housing having an opening;

[0229] S200. Provide an electrode assembly and install the electrode assembly into the housing;

[0230] S300. Provide an end cap, which includes a cap body and a convex portion. The cap body at least partially surrounds the outside of the convex portion. The convex portion protrudes from the inner surface of the cap body in the thickness direction of the end cap. A first recess that is recessed with respect to the outer surface of the cap body is formed at a position on the end cap corresponding to the convex portion.

[0231] S400. Abut the cap body against the housing, and then irradiate laser at the abutting portion of the cap body and the housing to weld the cap body to the housing, thereby covering the end cap on the opening.

[0232] Wherein, the convex portion protrudes from the inner surface of the cap body in the direction facing the electrode assembly and is used to block the laser when welding the cap body to the housing; the first recess is recessed from the outer surface of the cap body in the direction facing the electrode assembly and is used to release stress when welding the cap body to the housing.

[0233] It should be noted that for the related structure of the battery cell manufactured by the above manufacturing method of the battery cell, reference can be made to the battery cells provided in the above embodiments.

[0234] When assembling the battery cell based on the above manufacturing method of the battery cell, it is not necessary to perform the above steps in sequence. That is to say, the steps can be executed in the order mentioned in the embodiment, or can be executed in an order different from that mentioned in the embodiment, or several steps can be executed simultaneously. For example, the execution of steps S100 and S300 is not in sequence and can also be carried out simultaneously.

[0235] Figure 10 It is a schematic block diagram of a manufacturing system for a battery cell provided in some embodiments of the present application.

[0236] As shown in FIG. 11, an embodiment of the present application further provides a manufacturing system 90 for a battery cell, including:

[0237] A first providing device 91 for providing a housing having an opening.

[0238] A second providing device 92 for providing an electrode assembly and installing the electrode assembly into the housing.

[0239] A third providing device 93 for providing an end cap, which includes a cap body and a convex portion. The cap body at least partially surrounds the outside of the convex portion. The convex portion protrudes from the inner surface of the cap body in the thickness direction of the end cap. A first recess that is recessed with respect to the outer surface of the cap body is formed at a position on the end cap corresponding to the convex portion.

[0240] An assembling device 94 for abutting the cap body against the housing, and then irradiating laser at the abutting portion of the cap body and the housing to weld the cap body to the housing, thereby covering the end cap on the opening.

[0241] Among them, the convex portion protrudes from the inner surface of the cover body in the direction facing the electrode assembly and is used to block the laser when welding the cover body to the housing; the first concave portion depresses from the outer surface of the cover body in the direction facing the electrode assembly and is used to release stress when welding the cover body to the housing.

[0242] For the related structure of the battery cell manufactured by the above manufacturing system, reference can be made to the battery cells provided in the above embodiments.

[0243] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0244] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, comprising: A housing having an opening; An electrode assembly accommodated in the housing, the electrode assembly being of a wound structure, the electrode assembly including a first electrode tab, a second electrode tab and a separator, the separator being used to separate the first electrode tab and the second electrode tab, and the first electrode tab and the second electrode tab having opposite polarities; And An end cap, including a cap body and a convex portion, at least part of the cap body surrounding the outside of the convex portion and being used for laser welding with the housing so that the end cap covers the opening; In the thickness direction of the end cap, the convex portion protrudes from the inner surface of the cap body in the direction facing the electrode assembly and is used to block the laser when welding the cap body and the housing; A first concave portion is formed at a position corresponding to the convex portion on the end cap, the first concave portion being recessed from the outer surface of the cap body in the direction facing the electrode assembly and being used to release stress when welding the cap body and the housing; The cap body includes a first plate body and a second plate body, the first plate body surrounding the outside of the convex portion and being used for laser welding with the housing, and the convex portion surrounding the outside of the second plate body.

2. The battery cell according to claim 1, wherein, The housing has an outer end surface surrounding the opening, and the outer end surface of the housing is welded to the inner surface of the cap body so that the housing and the cap body are connected as a whole.

3. The battery cell according to claim 2, wherein, In the thickness direction, the bottom surface of the first concave portion is closer to the electrode assembly as a whole than the inner surface of the cap body.

4. The battery cell according to any one of claims 1-3, wherein, The housing includes a side wall, the side wall extending in the thickness direction and surrounding the outer periphery of the electrode assembly; The convex portion includes a blocking surface facing the side wall, the blocking surface being parallel to the thickness direction and extending from the inner surface of the cap body in the direction facing the electrode assembly.

5. The battery cell according to claim 4, wherein, The convex portion further includes a guiding surface facing the side wall, the guiding surface being connected to the end of the blocking surface away from the inner surface of the cap body, and the guiding surface being inclined in a direction away from the side wall compared with the blocking surface to guide the convex portion to be inserted into the housing.

6. The battery cell according to claim 1, wherein, A connecting portion is formed between the top surface of the convex portion and the bottom surface of the first concave portion, and the connecting portion is used for welding with the first tab of the electrode assembly.

7. The battery cell according to claim 6, further comprising a current collecting member, the current collecting member being used for electrically connecting the first tab of the electrode assembly and the end cap.

8. The battery cell according to claim 7, wherein, The current collecting member includes a first current collecting portion and a second current collecting portion connected to the first current collecting portion, the first current collecting portion being used for connecting the first tab so that the current collecting member and the first tab are electrically connected; the second current collecting portion surrounds the outside of the first current collecting portion, and the second current collecting portion is used for connecting at least one of the convex portion and the second plate body so that the current collecting member and the end cap are electrically connected.

9. The battery cell according to claim 8, wherein, The first current collecting portion is located between the second plate body and the first tab and is welded to the first tab, and the second current collecting portion is located between the first tab and the convex portion and is welded to the convex portion.

10. The battery cell according to claim 9, wherein, The current collecting member is in a flat plate shape.

11. The battery cell according to claim 9 or 10, wherein, The convex portion is supported on the electrode assembly through the current collecting member.

12. The battery cell according to claim 8, wherein, The current collector member is located between the second plate body and the first tab, and the convex portion surrounds the outside of the current collector member.

13. The battery cell according to claim 12, wherein, The second current collecting portion is welded to the second plate body, and the first current collecting portion is welded to the first tab.

14. The battery cell according to claim 12 or 13, wherein The first current collecting portion protrudes from the surface of the second current collecting portion facing the electrode assembly, and a second recess is formed at a position of the current collector member corresponding to the first current collecting portion, the second recess being recessed from the surface of the second current collecting portion facing away from the electrode assembly in the direction facing the electrode assembly.

15. The battery cell according to claim 14, wherein, Both the convex portion and the first current collecting portion are supported by the electrode assembly.

16. The battery cell according to claim 8, wherein, The end cap is provided with a pressure relief mechanism connected to the second plate body, and the pressure relief mechanism is configured to be actuated to release the internal pressure when the internal pressure of the battery cell reaches a threshold value; In the thickness direction, the first current collecting portion and the pressure relief mechanism are oppositely arranged, and there is a clearance gap between the first current collecting portion and the pressure relief mechanism.

17. The battery cell according to claim 16, wherein, The electrode assembly has a first through hole at the winding center; The first current collecting portion is provided with a second through hole, and the second through hole is oppositely arranged with the first through hole to communicate the first through hole with the clearance gap.

18. The battery cell according to claim 1, wherein, The first tab of the electrode assembly is electrically connected to the housing through the end cap.

19. The battery cell according to claim 18, wherein, The housing further includes a side wall and a bottom wall connected to the side wall, the side wall extends in the thickness direction and surrounds the outer periphery of the electrode assembly, and the bottom wall is provided with an electrode lead-out hole; The battery cell further includes an electrode terminal installed in the electrode lead-out hole, the electrode terminal is electrically connected to the second tab of the electrode assembly, and the first tab and the second tab have opposite polarities and are respectively located at both ends of the electrode assembly.

20. The battery cell according to claim 19, wherein The bottom wall and the side wall are integrally formed structures.

21. The battery cell according to any one of claims 18-20, wherein, The first tab is a negative tab, and the base material of the housing is steel.

22. The battery cell according to claim 1, wherein, The base material of the housing and the base material of the end cap are the same.

23. The battery cell according to claim 1, wherein, The battery cell is a cylindrical battery cell.

24. A battery, comprising a plurality of battery cells according to any one of claims 1-23.

25. An electrical device, comprising the battery according to claim 24, the battery being used to provide electrical energy.

26. A manufacturing method of a battery cell, comprising: Providing a housing having an opening; Providing an electrode assembly and installing the electrode assembly into the housing; Providing an end cap, the end cap including a cap body and a convex portion, at least a part of the cap body surrounds the outside of the convex portion, the convex portion protrudes from the inner surface of the cap body in the thickness direction of the end cap, and a first recess is formed at a position of the end cap corresponding to the convex portion, the first recess being recessed with respect to the outer surface of the cap body; the cap body includes a first plate body and a second plate body, the first plate body surrounds the outside of the convex portion and is used for laser welding with the housing, and the convex portion surrounds the outside of the second plate body; Abut the cover body against the housing, and then irradiate laser at the abutting portion between the cover body and the housing to weld the cover body to the housing, so that the end cover covers the opening; Wherein, the convex portion protrudes from the inner surface of the cover body in the direction facing the electrode assembly and is used to block the laser when welding the cover body to the housing; the first concave portion depresses from the outer surface of the cover body in the direction facing the electrode assembly and is used to release stress when welding the cover body to the housing.

27. A manufacturing system for a battery cell, comprising: A first providing device for providing a housing having an opening; A second providing device for providing an electrode assembly and installing the electrode assembly into the housing; A third providing device for providing an end cover, the end cover including a cover body and a convex portion, the cover body at least partially surrounding the outside of the convex portion, the convex portion protruding from the inner surface of the cover body in the thickness direction of the end cover, a first concave portion recessed relative to the outer surface of the cover body being formed at a position corresponding to the convex portion on the end cover; the cover body includes a first plate body and a second plate body, the first plate body surrounds the outside of the convex portion and is used for laser welding with the housing, and the convex portion surrounds the outside of the second plate body; An assembling device for abutting the cover body against the housing, and then irradiating laser at the abutting portion between the cover body and the housing to weld the cover body to the housing, so that the end cover covers the opening; Wherein, the convex portion protrudes from the inner surface of the cover body in the direction facing the electrode assembly and is used to block the laser when welding the cover body to the housing; the first concave portion depresses from the outer surface of the cover body in the direction facing the electrode assembly and is used to release stress when welding the cover body to the housing.

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