Battery cell, battery and electric device

Abstract

A battery cell, a battery and an electric device. The battery cell comprises a casing and a terminal assembly, wherein the casing comprises a wall portion, in which an electrode lead-out hole is formed. The terminal assembly comprises an electrode terminal, an insulating member and a fixing member, wherein at least part of the electrode terminal is located at the wall portion and covers the electrode lead-out hole, and the insulating member at least partially surrounds the electrode terminal and is connected to the electrode terminal. The fixing member comprises a body portion, a first connecting portion, and a first recess, wherein the body portion is fixed to the insulating member, the first connecting portion is connected to the body portion, the first recess is disposed on the side of the first connecting portion away from the wall portion in the thickness direction of the wall portion, and at least part of the first connecting portion surrounds an outer side of the first recess and is welded to the wall portion.

Description

Battery cells, batteries and electrical devices

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410930805.X, filed on July 11, 2024, entitled “Battery Cell, Battery and Electrical Device”, the entire contents of which are incorporated herein by reference. Technical Field

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

[0004] With the development of new energy technologies, batteries are being used more and more widely, for example in mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools.

[0005] In the development of battery technology, the reliability of individual battery cells directly affects the reliability, cost of use, and user experience of end products. Therefore, how to effectively improve the reliability of individual battery cells is a pressing technical problem that needs to be solved in battery technology. Summary of the Invention

[0006] In view of the above problems, this application provides a battery cell, a battery, and an electrical device that can effectively improve the reliability of the battery cell.

[0007] In a first aspect, embodiments of this application provide a battery cell, which includes a housing and a terminal assembly. The housing includes a wall portion with electrode lead-out holes. The terminal assembly includes electrode terminals, an insulating member, and a fixing member. At least a portion of the electrode terminals is located in the wall portion and covers the electrode lead-out holes. The insulating member at least partially surrounds and is connected to the electrode terminals. The fixing member includes a main body portion, a first connecting portion, and a first recess. The main body portion is fixed to the insulating member, the first connecting portion is connected to the main body portion, and the first recess is located on the side of the first connecting portion away from the wall portion along the thickness direction of the wall portion. At least a portion of the first connecting portion surrounds the outside of the first recess and is welded to the wall portion.

[0008] In the welding process between the first connecting part and the wall, the portion of the first connecting part surrounding the outer side of the first recess is heated and melts to form a molten pool, which can release the welding thermal stress in this part to a certain extent, thus improving the connection reliability between the first connecting part and the wall.

[0009] On the other hand, by introducing the first recess, the material of the first connecting part can be reduced, especially the material adjacent to the portion of the first connecting part surrounding the outside of the first recess. This allows part of the heat generated by welding the portion of the first connecting part surrounding the outside of the first recess with the wall to be transferred to the air inside the first recess, rather than directly to the material adjacent to the portion of the first connecting part surrounding the outside of the first recess and melting that material. This reduces the overall heat input of the first connecting part, thereby reducing welding thermal stress to a certain extent and reducing the generation of welding cracks.

[0010] On the other hand, after the portion of the first connecting part surrounding the outer side of the first recess melts upon heating to form a molten pool, the molten pool can spread along the inner wall of the first recess under the action of gravity, thus giving the molten pool good fluidity and reducing the generation of defects such as welding porosity, thereby improving welding quality. In this way, the connection stability between the terminal assembly and the wall can be improved, thereby effectively improving the reliability of the battery cell.

[0011] In some embodiments of the first aspect, the first connecting portion includes a first protrusion, the position of which corresponds to the position of the first recess, the first protrusion protruding from the side surface of the main body portion facing the wall portion and abutting against the wall portion.

[0012] The first protrusion abuts against the wall, ensuring a certain gap between the connection between the first connecting part and the main body and the wall, thus forming a cantilever structure. During the welding process between the first connecting part and the wall, the connection between the first connecting part and the main body can release welding thermal stress through its own micro-variation, thereby further improving the welding quality between the terminal assembly and the wall, and further improving the reliability of the battery cell.

[0013] In some embodiments of the first aspect, the first distance H1 between the side surface of the first protrusion facing the wall and the side surface of the main body facing the wall and the first thickness T1 of the main body satisfy the relationship: 0.25≤H1 / T1≤4.

[0014] The above technical solution sets the ratio H1 / T1 between the first distance H1 and the first thickness T1 within the above range, and reasonably sets the first distance H1 between the side surface of the first protrusion facing the wall and the side surface of the main body facing the wall based on the first thickness T1 of the main body. This can satisfy the good effect of releasing welding thermal stress, while avoiding the first protrusion from having too much impact on the energy density of the battery cell to a certain extent.

[0015] In some embodiments of the first aspect, the first connecting portion includes an abutting surface and a guiding surface. The abutting surface abuts against the wall portion along its thickness direction, and the guiding surface slopes from one end of the abutting surface toward the side of the abutting surface away from the wall portion. The first connecting portion is welded to the wall portion to form a welded portion, and the end of the guiding surface away from the abutting surface extends to the welded portion.

[0016] On the one hand, the guide surface can play a guiding role in the assembly process between the fastener and the wall, improving the assembly accuracy between the fastener and the wall. On the other hand, compared with right-angled edges, the introduction of the guide surface can also reduce the machining difficulty of the first connection part.

[0017] In some embodiments of the first aspect, the first dimension W1 of the guide surface in the radial direction of the electrode lead-out hole and the first thickness T1 of the main body satisfy the relationship: 0.1≤W1 / T1≤1.

[0018] The above technical solution sets the ratio W1 / T1 between the first dimension W1 and the first thickness T1 within the above range, and reasonably sets the first dimension W1 of the guide surface in the radial direction of the electrode lead-out hole based on the first thickness T1 of the main body. This can ensure that the guide surface has a good guiding effect while avoiding excessive influence on the structural strength of the first connection part to a certain extent.

[0019] In some embodiments of the first aspect, the first connecting portion includes a first part and a second part, the first part surrounding the outer side of the first recess, the second part surrounding the inner side of the first recess, and the second part connecting the first part and the main body.

[0020] In the welding process between the first connecting part and the wall, the first part melts to form a molten pool. Under the action of gravity, the molten pool can spread along the inner wall of the first recess. The second part can block the molten pool located in the first recess to a certain extent, so as to reduce the risk of interference between the molten pool and the insulating part, which may lead to damage to the insulating part.

[0021] In some embodiments of the first aspect, the first thickness T1 of the main body and the second thickness T2 of the second part satisfy the relationship: 0.5≤T2 / T1≤4.

[0022] The above technical solution sets the ratio T2 / T1 between the second thickness T2 and the first thickness T1 within the above range, and reasonably sets the second thickness T2 of the second part based on the first thickness T1 of the main body. This can ensure that the second part has good structural strength while avoiding excessive impact on the energy density of the battery cell to a certain extent.

[0023] In some embodiments of the first aspect, the first connecting portion further includes a third portion connected between the first portion and the second portion, the first portion, the second portion and the third portion together defining the first recess.

[0024] The introduction of the third part can increase the size of the first recess in the direction perpendicular to the thickness direction of the wall, thereby increasing the accommodating volume of the first recess and further improving the effect on the fluidity of the molten pool.

[0025] In some embodiments of the first aspect, the third part has a second dimension W2 on the side surface facing away from the wall in a direction perpendicular to the thickness direction of the wall, and the first thickness T1 and the second dimension W2 of the main body satisfy the relationship: 0.1≤W2 / T1≤7.

[0026] The above technical solution sets the ratio W2 / T1 between the second dimension W2 and the first thickness T1 within the above range. Based on the first thickness T1 of the main body, the surface of the third part facing away from the wall has a second dimension W2 in a direction perpendicular to the thickness direction of the wall. This can ensure that the accommodating volume of the first recess meets the requirements, while avoiding excessive impact of the third part on the energy density of the battery cell to a certain extent.

[0027] In some embodiments of the first aspect, the third portion has a third dimension W3 on one side surface facing the wall portion in a direction perpendicular to the thickness direction of the wall portion, and the first thickness T1 of the main body portion and the third dimension W3 satisfy the relationship: 0.25≤W3 / T1≤10.

[0028] The above technical solution sets the ratio W3 / T1 between the third dimension W3 and the first thickness T1 within the above range. Based on the first thickness T1 of the main body, the surface of the third part facing the wall is reasonably set to have a third dimension W3 in a direction perpendicular to the thickness direction of the wall. This can ensure that the overall structural stability of the first connection part meets the requirements, while avoiding excessive impact of the third part on the energy density of the battery cell to a certain extent.

[0029] In some embodiments of the first aspect, the first thickness T1 of the main body and the third thickness T3 of the third part satisfy the relationship: 0.4≤T3 / T1≤2.5.

[0030] The above technical solution sets the ratio T3 / T1 between the third thickness T3 and the first thickness T1 within the above range, and reasonably sets the third thickness T3 of the third part based on the first thickness T1 of the main body. This can ensure that the third part meets good structural strength while avoiding excessive impact of the third part on the energy density of the battery cell to a certain extent.

[0031] In some embodiments of the first aspect, the first connecting portion further includes a first arcuate surface, which connects the side surface of the third portion facing away from the wall portion and the side surface of the first portion facing the first recess.

[0032] On the one hand, as the molten pool flows and spreads along the inner wall of the first recess, the introduction of the first arc surface allows the molten pool to flow more smoothly and evenly, thereby further improving the flow performance of the molten pool and thus improving the welding quality. On the other hand, the first arc surface also helps to reduce the risk of stress concentration between the first and third parts, improving the connection stability between the terminal assembly and the wall, thereby helping to further improve the reliability of the battery cell.

[0033] In some embodiments of the first aspect, the first radian R1 of the first arc surface satisfies the relationship: 0.25mm≤R1≤5mm.

[0034] The above technical solution, by setting the first arc R1 of the first arc surface within the above range, enables the first arc surface to satisfy its own structural effect while reducing the difficulty of setting the first arc surface.

[0035] In some embodiments of the first aspect, the first connecting portion further includes a second arcuate surface, which connects the side surface of the third portion facing away from the wall portion and the side surface of the second portion facing the first recess.

[0036] The second arc surface helps reduce the risk of stress concentration between the second and third parts, and can improve the connection stability between the terminal assembly and the wall, thereby helping to further improve the reliability of the battery cell.

[0037] In some embodiments of the first aspect, the second arcuate radius R2 of the second arc surface satisfies the relationship: 0.5mm ≤ R2 ≤ 6mm.

[0038] The above technical solution, by setting the second arc R2 of the second arc surface within the above range, enables the second arc surface to reduce the risk of stress concentration between the second part and the third part while also reducing the difficulty of setting the second arc surface.

[0039] In some embodiments of the first aspect, a groove is provided on the outer side of the wall portion, and at least a portion of the first connecting portion is accommodated within the groove.

[0040] By introducing a groove to accommodate the first connection part, the space occupied by the first connection part on the external space of the battery cell can be effectively reduced, thereby helping to improve the energy density of the battery cell.

[0041] In some embodiments of the first aspect, the main body includes a fourth part and a fifth part, the fifth part being connected to the fourth part and the first connecting part, the fourth part being embedded inside the insulating member, and the fifth part being exposed outside the insulating member.

[0042] The above-mentioned technical solution, on the one hand, can improve the connection stability between the fixing member and the insulating member by embedding the fourth part inside the insulating member; on the other hand, by exposing the fifth part to the outside of the insulating member, it can not only simplify the manufacturing difficulty of the first connecting part, but also reduce the risk of interference between the insulating member and the first connecting part affecting the connection effect between the first connecting part and the wall.

[0043] In some embodiments of the first aspect, the end face of the portion of the first connecting part surrounding the outside of the first recess, on the side away from the wall in the thickness direction, is flush with the surface of the fifth portion on the side away from the wall in the thickness direction. This improves the overall structural consistency of the fastener.

[0044] In some embodiments of the first aspect, the housing includes a housing and an end cap, the housing having an opening, the end cap closing onto the opening, and the end cap being configured as a wall portion.

[0045] In some embodiments of the first aspect, the battery cell further includes an electrode assembly housed within a housing. The end cap includes a cap body, a second connecting portion, and a second recess. The second connecting portion is connected to the cap body, and the second recess is disposed on the side of the second connecting portion facing away from the electrode assembly. At least a portion of the second connecting portion surrounds the outside of the second recess and is welded to the housing.

[0046] In the welding process between the second connecting part and the shell, the portion of the second connecting part surrounding the outer side of the second recess is heated and melts to form a molten pool, which can release the welding thermal stress of this part to a certain extent and improve the connection reliability between the second connecting part and the shell.

[0047] On the other hand, by introducing the second recess, the material of the second connecting part can be reduced, especially the material adjacent to the portion of the second connecting part surrounding the outer side of the second recess. This allows some of the heat generated by welding the portion of the second connecting part surrounding the outer side of the second recess with the shell to be transferred to the air inside the second recess, rather than directly to the material adjacent to the portion of the second connecting part surrounding the outer side of the second recess and melting that material. This reduces the overall heat input of the second connecting part, thereby reducing welding thermal stress to a certain extent and reducing the generation of welding cracks.

[0048] On the other hand, after the portion of the second connecting part surrounding the outer side of the second recess melts upon heating to form a molten pool, the molten pool can spread along the inner wall of the second recess under the action of gravity, thus giving the molten pool good fluidity and reducing the generation of defects such as welding porosity, thereby improving welding quality. In this way, the connection stability between the end cap and the casing can be improved, thereby effectively improving the reliability of the battery cell.

[0049] In some embodiments of the first aspect, the second connecting portion includes a second protrusion, the position of which corresponds to the position of the second recess, the second protrusion protruding from the side surface of the cover body facing the electrode assembly.

[0050] The second protrusion protrudes from the surface of the cover body facing the electrode assembly, enabling the second connection to form a cantilever structure. During the welding process between the second connection and the housing, the second connection can release welding thermal stress through its own micro-variation, thereby further improving the welding quality between the end cover and the housing and further improving the reliability of the battery cell.

[0051] Secondly, this application provides a battery comprising the battery cell provided in any embodiment of the first aspect.

[0052] Thirdly, this application provides an electrical device that includes a battery cell provided in any embodiment of the first aspect, the battery cell being used to provide electrical energy.

[0053] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0054] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0055] Figure 1 is a schematic diagram of the vehicle structure provided in some embodiments of this application;

[0056] Figure 2 is a schematic diagram of the exploded structure of a battery provided in some embodiments of this application;

[0057] Figure 3 is a schematic diagram of the structure of a battery module provided in some embodiments of this application;

[0058] Figure 4 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0059] Figure 5 is a schematic diagram of the cross-sectional structure along AA in Figure 4;

[0060] Figure 6 is a partially enlarged structural schematic diagram of the structure shown in Figure 5;

[0061] Figure 7 is a partially enlarged structural schematic diagram of the structure shown in Figure 6;

[0062] Figure 8 is a partial enlarged structural diagram of point H in Figure 7;

[0063] Figure 9 is a schematic diagram of another battery cell provided in some embodiments of this application;

[0064] Figure 10 is a schematic diagram of the cross-sectional structure along BB in Figure 9;

[0065] Figure 11 is a partially enlarged schematic diagram of the structure shown in Figure 10.

[0066] The reference numerals in the detailed embodiments are as follows: 1. Vehicle; 2. Battery; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Accommodation space; 6. Battery module; 7. Battery cell; 10. Outer shell; 10a. Housing; 10b. End cap; 11. Wall section; 111. Electrode lead-out hole; 112. Groove; 20. Terminal assembly; 21. Electrode terminal; 22. Insulating component; 23. Fixing component; 231. Main body; 2311. Fourth part; 2312. Fifth part; 232. First connecting part; 2321. First part; 2322. Second part; 2323. Third part; 233. First recess; 234. First protrusion; 235. Abutting surface; 236. Guide surface; 237. First arc surface; 238. Second arc surface; 30. Electrode assembly; 40. Cover body; 50. Second connecting part; 60. Second recess; 70. Second protrusion; X, thickness direction. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0068] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, rather than to describe a specific order or hierarchy.

[0069] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0070] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0071] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0072] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0073] In this application, "multiple" means two or more (including two).

[0074] In this application, the term "parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism as commonly understood in engineering; similarly, "perpendicular" includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity as commonly understood in engineering.

[0075] In this embodiment of the application, the battery cell can be a secondary battery cell, which refers to a battery cell that can be used again after being discharged by recharging to activate the active materials.

[0076] The battery cell can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc., but the embodiments of this application are not limited to this.

[0077] A single battery cell typically includes an electrode assembly. The electrode assembly consists of a positive electrode and a negative electrode. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes.

[0078] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes, which can prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0079] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a layer of positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0080] In some embodiments, the negative electrode may be a negative electrode sheet, which may include a negative electrode current collector and a layer of negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0081] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0082] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0083] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0084] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0085] Gel electrolytes consist of a polymer-based electrolyte backbone network combined with an ionic liquid—lithium salt.

[0086] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0087] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0088] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphorus sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0089] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0090] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0091] In some implementations, the electrode assembly is a stacked structure.

[0092] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0093] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0094] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0095] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0096] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0097] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0098] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0099] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0100] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0101] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0102] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0103] In some embodiments, the battery can be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0104] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0105] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0106] With the development of new energy technologies, batteries are being used more and more widely, for example in mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools.

[0107] In the development of battery technology, the reliability of individual battery cells directly affects the reliability, cost of use, and user experience of end products. A single battery cell consists of a casing and terminal assemblies, and welding is typically used to achieve an effective and secure connection between the casing and the terminal assemblies.

[0108] However, during the welding process, the welding thermal stress in the joint will form a stress concentration area in the local area of ​​the weld between the shell and the terminal assembly. Furthermore, the current welding joint area between the shell and the terminal assembly is a flat butt structure, which cannot effectively release the welding thermal stress generated during the welding process. As a result, microcracks or micropores often form at the weld end and in the vicinity of the joint, which reduces the connection reliability of the weld between the shell and the terminal assembly, and thus affects the overall reliability of the battery cell.

[0109] Based on the above considerations, this application provides a battery cell, which includes a housing and a terminal assembly. The housing includes a wall portion with electrode lead-out holes. The terminal assembly includes electrode terminals, an insulating member, and a fixing member. At least a portion of the electrode terminals is located in the wall portion and covers the electrode lead-out holes. The insulating member at least partially surrounds and is connected to the electrode terminals. The fixing member includes a main body portion, a first connecting portion, and a first recess. The main body portion is fixed to the insulating member, the first connecting portion is connected to the main body portion, and the first recess is located on the side of the first connecting portion away from the wall portion along the thickness direction of the wall portion. At least a portion of the first connecting portion surrounds the outside of the first recess and is welded to the wall portion.

[0110] During the welding process between the first connecting part and the wall, on the one hand, the portion of the first connecting part surrounding the outer side of the first recess melts upon heating to form a molten pool, which can release the welding thermal stress in this part to a certain extent, thus improving the connection reliability between the first connecting part and the wall. On the other hand, by introducing the first recess, the material of the first connecting part can be reduced, especially the material adjacent to the portion of the first connecting part surrounding the outer side of the first recess. This allows some of the heat generated during the welding of the portion of the first connecting part surrounding the outer side of the first recess with the wall to be transferred to the air inside the first recess, rather than directly to the material adjacent to the portion of the first connecting part surrounding the outer side of the first recess and melting that material. This reduces the overall heat input of the first connecting part, thereby reducing welding thermal stress to a certain extent and reducing the generation of welding cracks. Furthermore, after the portion of the first connecting part surrounding the outer side of the first recess melts upon heating to form a molten pool, the molten pool can spread along the inner wall of the first recess under the action of gravity, thus giving the molten pool good fluidity, reducing the generation of defects such as welding porosity, and thus improving the welding quality.

[0111] The technical solutions described in the embodiments of this application are applicable to batteries and electrical devices that use batteries.

[0112] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, among others. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.

[0113] It should be understood that the technical solutions described in the embodiments of this application are not limited to the batteries and electrical devices described above, but can also be applied to all batteries including battery boxes and electrical devices using batteries. However, for the sake of brevity, the following embodiments are all illustrated using electric vehicles as examples.

[0114] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0115] Referring again to Figure 1, a battery 2 is installed inside the vehicle 1. The battery 2 can be located at the bottom, front, or rear of the vehicle 1. The battery 2 can be used to power the vehicle 1; for example, the battery 2 can serve as the operating power source for the vehicle 1.

[0116] Vehicle 1 may also include controller 3 and motor 4. Controller 3 is used to control battery 2 to supply power to motor 4, for example, for the power needs of vehicle 1 during start-up, navigation and driving.

[0117] In some embodiments of this application, the battery 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0118] Figure 2 is a schematic diagram of the exploded structure of a battery provided in some embodiments of this application.

[0119] Referring again to Figure 2, battery 2 includes a housing 5 and individual battery cells, with the individual battery cells housed within the housing 5.

[0120] The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the individual battery cells. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0121] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0122] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0123] In battery 2, there can be one or more individual battery cells. If there are multiple individual battery cells, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple individual battery cells are connected in both series and parallel configurations. Multiple individual battery cells can be directly connected in series, parallel, or in a mixed configuration and then housed within housing 5. Alternatively, multiple individual battery cells can first be connected in series, parallel, or in a mixed configuration to form battery module 6, and then multiple battery modules 6 can be connected in series, parallel, or in a mixed configuration to form a whole and housed within housing 5.

[0124] Figure 3 is a schematic diagram of the structure of a battery module provided in some embodiments of this application.

[0125] In some embodiments, continuing to refer to the figures, there are multiple battery cells 7, which are first connected in series, parallel, or mixed to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or mixed to form a whole and housed in a casing.

[0126] Multiple battery cells 7 in battery module 6 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6.

[0127] Figure 4 is a structural schematic diagram of a battery cell provided in some embodiments of this application; Figure 5 is a cross-sectional structural schematic diagram along AA in Figure 4; Figure 6 is a partially enlarged structural schematic diagram of the structure shown in Figure 5; Figure 7 is a partially enlarged structural schematic diagram of the structure shown in Figure 6; and Figure 8 is a partially enlarged structural schematic diagram of H in Figure 7.

[0128] Referring to Figures 4 to 8, this application embodiment provides a battery cell 7, which includes a housing 10 and a terminal assembly 20. The housing 10 includes a wall portion 11, and the wall portion 11 is provided with an electrode lead-out hole 111. The terminal assembly 20 includes an electrode terminal 21, an insulating member 22, and a fixing member 23. At least a portion of the electrode terminal 21 is located in the wall portion 11 and covers the electrode lead-out hole 111. The insulating member 22 at least partially surrounds the electrode terminal 21 and is connected to the electrode terminal 21. The fixing member 23 includes a main body portion 231, a first connecting portion 232, and a first recess 233. The main body portion 231 is fixed to the insulating member 22. The first connecting portion 232 is connected to the main body portion 231. The first recess 233 is disposed on the side of the first connecting portion 232 opposite to the wall portion 11 along the thickness direction X. At least a portion of the first connecting portion 232 surrounds the outside of the first recess 233 and is welded to the wall portion 11.

[0129] Exemplarily, the housing 10 is a component used to form the internal environment of the battery cell 7. The formed internal environment can accommodate the electrode assembly 30, electrolyte, and other components. Optionally, the housing 10 can be, but is not limited to, made of metallic or non-metallic materials. For example, metallic materials can be copper, aluminum, or stainless steel; non-metallic materials can be polyethylene, polypropylene, or polyvinyl chloride.

[0130] In some examples, the housing 10 can be a sealed structure or a non-sealed structure. As an example, when the housing 10 is a sealed structure, it can protect the electrode assembly 30 and prevent, to some extent, electrolyte leakage. When the housing 10 is a non-sealed structure, it can still protect the electrode assembly 30, and a sealing bag may be included between the housing 10 and the electrode assembly 30. The sealing bag is used to encapsulate the electrode assembly 30 and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film.

[0131] The battery cell 7 may also include an electrode assembly 30, which is housed within the casing 10a. The electrode assembly 30 is the component in the battery cell 7 where the electrochemical reaction occurs. The electrode assembly 30 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body 231 of the electrode assembly 30, while the portions of the positive and negative electrode sheets without active material each constitute a tab. The positive and negative tabs may be located together at one end of the main body 231 or separately at both ends of the main body 231. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs connect to the electrode terminals 21 to form a current loop.

[0132] In some examples, at least a portion of the electrode terminal 21 is located within and covers the electrode lead-out hole 111.

[0133] In some examples, at least a portion of the electrode terminal 21 is located outside the wall portion 11 and covers the electrode lead-out hole 111, wherein the outside of the wall portion 11 refers to the side of the wall portion 11 facing away from the electrode assembly 30.

[0134] The outer side of the first recess 233 refers to the side of the first recess 233 that is away from the main body 231 in a direction perpendicular to the thickness direction X of the wall portion 11.

[0135] The insulating member 22 is used to insulate the electrode terminal 21 and the fixing member 23, which is used to fix the electrode terminal 21 to the wall portion 11. As an example, the insulating member 22 is inserted into the electrode terminal 21.

[0136] Optionally, the insulating component 22 may be, but is not limited to, made of insulating materials such as polyethylene, polypropylene, polyvinyl chloride, or rubber. The fastener 23 may be, but is not limited to, made of materials such as copper, copper alloy, aluminum, aluminum alloy, or steel.

[0137] The main body 231 can be detachably connected to the insulating member 22, or it can be integrally formed on the insulating member 22. The main body 231 can be directly connected to the insulating member 22, or it can be constrained to the insulating member 22 by other components. As an example, the connection method between the main body 231 and the insulating member 22 can be, but is not limited to, bolt connection, welding, riveting, bonding, or snap-fit.

[0138] In some examples, the insulating element 22 is formed on the main body 231 by injection molding.

[0139] The first connecting part 232 can be detachably connected to the main body 231, or it can be integrally provided on the main body 231. The first connecting part 232 can be directly connected to the main body 231, or it can be constrained to the main body 231 by other components. As an example, the connection method between the first connecting part 232 and the main body 231 can be, but is not limited to, bolt connection, welding, riveting, bonding, or snap-fit.

[0140] In some examples, the first connecting portion 232 and the main body portion 231 are integrally formed. On the one hand, there is no need to connect the first connecting portion 232 and the main body portion 231 through an additional connecting process, simplifying the manufacturing process. At the same time, compared with connecting the first connecting portion 232 and the main body portion 231 through an additional connecting process, the integral structure of the first connecting portion 232 and the main body portion 231 has a higher connection strength.

[0141] The first recess 233 may be an annular groove surrounding the outside of the main body 231. At least a portion of the first connecting portion 232 surrounds the outside of the first recess 233. This can be understood as a portion of the first connecting portion 232 surrounding the outside of the first recess 233, or all of the first connecting portion 232 surrounding the outside of the first recess 233.

[0142] The portion of the first connecting part 232 surrounding the outside of the first recess 233 is welded to the wall part 11 to form a welded part, thereby achieving a fixed connection between the fastener 23 and the wall part 11. Optionally, the welding method between the first connecting part 232 and the wall part 11 can be, but is not limited to, plasma welding, electron beam welding, brazing, pressure welding, etc.

[0143] In the welding process between the first connecting part 232 and the wall part 11, the portion of the first connecting part 232 surrounding the outside of the first recess 233 is heated and melts to form a molten pool, which can release the welding thermal stress of this part to a certain extent, thus improving the connection reliability between the first connecting part 232 and the wall part 11.

[0144] On the other hand, by introducing the first recess 233, the material of the first connecting portion 232 can be reduced, especially the material adjacent to the portion of the first connecting portion 232 surrounding the outside of the first recess 233. This allows part of the heat generated by welding the portion of the first connecting portion 232 surrounding the outside of the first recess 233 with the wall portion 11 to be transferred to the air inside the first recess 233, rather than directly to the material adjacent to the portion of the first connecting portion 232 surrounding the outside of the first recess 233 and melting that material. This reduces the overall heat input of the first connecting portion 232, thereby reducing welding thermal stress to a certain extent and reducing the generation of welding cracks.

[0145] On the other hand, after the portion of the first connecting part 232 surrounding the outside of the first recess 233 melts upon heating to form a molten pool, the molten pool can spread along the inner wall of the first recess 233 under the action of gravity, thereby giving the molten pool good fluidity, reducing the generation of defects such as welding porosity, and thus improving welding quality. In this way, the connection stability between the terminal assembly 20 and the wall 11 can be improved, thereby effectively improving the reliability of the battery cell 7.

[0146] In some embodiments, the first connecting portion 232 includes a first protrusion 234, the position of which corresponds to the position of the first recess 233. The first protrusion 234 protrudes from the side surface of the main body portion 231 facing the wall portion 11 and abuts against the wall portion 11.

[0147] The position of the first protrusion 234 corresponds to the position of the first concave portion 233. It can be understood that the projection of the first protrusion 234 on the thickness direction X of the wall portion 11 and the projection of the first concave portion 233 on the thickness direction X of the wall portion 11 at least partially overlap.

[0148] In some examples, the first recess 233 can be formed by stamping on the first connecting portion 232 to simultaneously form the first protrusion 234 protruding from the side surface of the main body portion 231 facing the wall portion 11, thereby simplifying the overall manufacturing process.

[0149] The first protrusion 234 abuts against the wall portion 11, ensuring a certain gap between the connection portion of the first connecting portion 232 and the main body portion 231 and the wall portion 11, thereby forming a cantilever structure for the first connecting portion 232. During the welding process between the first connecting portion 232 and the wall portion 11, the connection portion of the first connecting portion 232 and the main body portion 231 can release welding thermal stress through its own micro-variation, thereby further improving the welding quality between the terminal assembly 20 and the wall portion 11, and further improving the reliability of the battery cell 7.

[0150] In some embodiments, the first distance H1 between the side surface of the first protrusion 234 facing the wall portion 11 and the side surface of the main body portion 231 facing the wall portion 11 and the first thickness T1 of the main body portion 231 satisfy the relationship: 0.25≤H1 / T1≤4.

[0151] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231. The first distance H1 between the side surface of the first protrusion 234 facing the wall portion 11 and the side surface of the main body 231 facing the wall portion 11 can be understood as the height by which the first protrusion 234 protrudes from the side surface of the main body 231 facing the wall portion 11.

[0152] As an example, the ratio H1 / T1 between the first distance H1 and the first thickness T1 can be, but is not limited to, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, 4, etc.

[0153] When the first thickness T1 of the main body 231 is constant, the larger the first distance H1 between the surface of the first protrusion 234 facing the wall 11 and the surface of the main body 231 facing the wall 11, the larger the space for micro-variation of the connection between the first connecting part 232 and the main body 231, and the better the effect of releasing welding heat stress. At the same time, the larger the space occupied by the first connecting part 232 in the thickness direction X of the wall 11, the greater the impact on the energy density of the battery cell 7, that is, it is easy to cause the energy density of the battery cell 7 to decrease. Similarly, the smaller the first distance H1, the worse the effect of releasing welding heat stress, and the smaller the impact on the energy density of the battery cell 7.

[0154] The setting of the first distance H1 between the surface of the first protrusion 234 facing the wall portion 11 and the surface of the main body 231 facing the wall portion 11 also needs to fully consider the first thickness T1 of the main body 231. If the first thickness T1 of the main body 231 is too large and the first distance H1 is too small, it will make the overall setting of the first protrusion 234 too difficult; if the first thickness T1 of the main body 231 is too small and the first distance H1 is too large, the overall structural stability of the first connecting portion 232 will be weak.

[0155] Thus, by setting the ratio H1 / T1 between the first distance H1 and the first thickness T1 within the above range, the first distance H1 between the side surface of the first protrusion 234 facing the wall portion 11 and the side surface of the main body 231 facing the wall portion 11 is reasonably set based on the first thickness T1 of the main body portion 231. This can satisfy the good effect of releasing welding thermal stress, while avoiding the first protrusion 234 from having too much impact on the energy density of the battery cell 7.

[0156] Furthermore, the first distance H1 and the first thickness T1 satisfy the relationship: 0.5 ≤ H1 / T1 ≤ 2. As an example, the ratio H1 / T1 between the first distance H1 and the first thickness T1 can be, but is not limited to, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc.

[0157] In some embodiments, the first distance H1 satisfies the relationship: 0.5mm ≤ H1 ≤ 1mm. As an example, the first distance H1 can be, but is not limited to, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1mm.

[0158] In some embodiments, the first connecting portion 232 includes an abutting surface 235 and a guiding surface 236. The abutting surface 235 abuts against the wall portion 11 along the thickness direction X, and the guiding surface 236 is inclined from one end of the abutting surface 235 toward the side of the abutting surface 235 away from the wall portion 11. The first connecting portion 232 is welded to the wall portion 11 to form a welded portion, and the end of the guiding surface 236 away from the abutting surface 235 extends to the welded portion.

[0159] On the one hand, the guide surface 236 can play a guiding role in the assembly process of the fastener 23 and the wall portion 11, thereby improving the assembly accuracy between the fastener 23 and the wall portion 11. On the other hand, compared with the right-angled side, the introduction of the guide surface 236 can also reduce the processing difficulty of the first connecting portion 232.

[0160] In some embodiments, the distance between the guide surface 236 and the wall portion 11 along the thickness direction X is linearly increased in the direction perpendicular to the thickness direction X of the wall portion 11 and in the direction from the abutment surface 235 to the guide surface 236. This helps to reduce the processing difficulty of the guide surface 236, thereby reducing costs.

[0161] In some embodiments, the first dimension W1 of the guide surface 236 in the radial direction of the electrode lead-out hole 111 and the first thickness T1 of the main body 231 satisfy the relationship: 0.1≤W1 / T1≤1.

[0162] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231. The first dimension W1 of the guide surface 236 in the radial direction of the electrode lead-out hole 111 can be understood as the dimension of the first projection of the guide surface 236 in a direction perpendicular to the thickness direction X of the wall portion 11, wherein the first projection is the projection of the guide surface 236 along the thickness direction X of the wall portion 11.

[0163] As an example, the ratio W1 / T1 between the first dimension W1 and the first thickness T1 can be, but is not limited to, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc.

[0164] When the first thickness T1 of the main body 231 is constant, the larger the first dimension W1 of the guide surface 236 in the radial direction of the electrode lead-out hole 111, the better the guiding effect of the guide surface 236. At the same time, the greater the influence of the guide surface 236 on the overall structural strength of the first connecting part 232, that is, it is easy to cause insufficient material in the first connecting part 232 at the position of the guide surface 236, thus reducing the structural strength of the first connecting part 232. Similarly, the smaller the first dimension W1, the worse the guiding effect of the guide surface 236, and the smaller the influence on the overall structural strength of the first connecting part 232.

[0165] The setting of the first dimension W1 of the guide surface 236 in the radial direction of the electrode lead-out hole 111 also needs to fully consider the first thickness T1 of the main body 231. If the first thickness T1 of the main body 231 is too large and the first dimension W1 is too small, it will make the overall setting of the guide surface 236 too difficult; if the first thickness T1 of the main body 231 is too small and the first dimension W1 is too large, the overall structural stability of the first connecting part 232 will be weak.

[0166] Thus, by setting the ratio W1 / T1 between the first dimension W1 and the first thickness T1 within the above range, the first dimension W1 of the guide surface 236 in the radial direction of the electrode lead-out hole 111 is reasonably set based on the first thickness T1 of the main body 231. This can ensure that the guide surface 236 has a good guiding effect while avoiding excessive influence of the guide surface 236 on the structural strength of the first connecting part 232 to a certain extent.

[0167] Furthermore, the first dimension W1 and the first thickness T1 satisfy the relationship: 0.2 ≤ W1 / T1 ≤ 0.5. As an example, the ratio W1 / T1 between the first dimension W1 and the first thickness T1 can be, but is not limited to, 0.2, 0.22, 0.25, 0.27, 0.3, 0.32, 0.35, 0.37, 0.4, 0.42, 0.45, 0.47, 0.5, etc.

[0168] In some embodiments, the first dimension W1 satisfies the relationship: 0.2mm ≤ W1 ≤ 0.4mm. As an example, the first dimension W1 can be, but is not limited to, 0.2mm, 0.25mm, 0.3mm, 0.35mm, or 0.4mm.

[0169] In some embodiments, the first connecting portion 232 includes a first portion 2321 and a second portion 2322, the first portion 2321 surrounding the outer side of the first recess 233, the second portion 2322 surrounding the inner side of the first recess 233, and the second portion 2322 connecting the first portion 2321 and the main body portion 231.

[0170] The first part 2321 is welded to the wall portion 11 to form a welded part. This can be done by welding a portion of the material in the first part 2321 to the wall portion 11, or by welding all of the material in the first part 2321 to the wall portion 11. The inner side of the first recess 233 refers to the side of the first recess 233 closest to the main body portion 231 in a direction perpendicular to the thickness direction X of the wall portion 11.

[0171] The first part 2321 can be detachably connected to the second part 2322, or it can be integrally formed on the second part 2322. The first part 2321 can be directly connected to the second part 2322, or it can be constrained to the second part 2322 by other components. As an example, the connection method between the first part 2321 and the second part 2322 can be, but is not limited to, bolt connection, welding, riveting, bonding, or snap-fit.

[0172] In some examples, the first part 2321 and the second part 2322 are integrally molded structures. On the one hand, there is no need to connect the first part 2321 and the second part 2322 through an additional connecting process, simplifying the manufacturing process. At the same time, compared with connecting the first part 2321 and the second part 2322 through an additional connecting process, the integral structure of the first part 2321 and the second part 2322 has a higher connection strength.

[0173] In the welding process between the first connecting part 232 and the wall part 11, the first part 2321 melts to form a molten pool. Under the action of gravity, the molten pool can spread out along the inner wall of the first recess 233. The second part 2322 can block the molten pool located in the first recess 233 to a certain extent, so as to reduce the risk of interference between the molten pool and the insulating part 22, which would cause damage to the insulating part 22.

[0174] In the example where the first connecting portion 232 includes a first protrusion 234, the first protrusion 234 abuts against the wall portion 11, ensuring at least a certain gap exists between the second portion 2322 and the wall portion 11, thereby enabling the first connecting portion 232 to form a cantilever structure. During the welding process between the first connecting portion 232 and the wall portion 11, the second portion 2322 can release welding thermal stress through its own micro-variation, thereby further improving the welding quality between the terminal assembly 20 and the wall portion 11, and further improving the reliability of the battery cell 7.

[0175] In some embodiments, the first thickness T1 of the main body 231 and the second thickness T2 of the second part 2322 satisfy the relationship: 0.5≤T2 / T1≤4.

[0176] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231, and the second thickness T2 of the second part 2322 can be understood as the thickness of the sheet constituting the second part 2322.

[0177] As an example, the ratio T2 / T1 between the second thickness T2 and the first thickness T1 can be, but is not limited to, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, 4, etc.

[0178] When the first thickness T1 of the main body 231 is constant, the larger the second thickness T2 of the second part 2322, the better the structural strength of the second part 2322; at the same time, the larger the space occupied by the second part 2322, the greater its impact on the energy density of the battery cell 7, that is, it is more likely to cause a decrease in the energy density of the battery cell 7. Similarly, the smaller the second thickness T2 of the second part 2322, the worse the structural strength of the second part 2322, and the smaller its impact on the energy density of the battery cell 7.

[0179] The setting of the second thickness T2 of the second part 2322 also needs to fully consider the first thickness T1 of the main body 231. If the first thickness T1 of the main body 231 is too large and the second thickness T2 is too small, or if the first thickness T1 of the main body 231 is too small and the second thickness T2 is too large, the overall structural stability of the fastener 23 will be weak and the structural consistency will be poor.

[0180] Thus, by setting the ratio T2 / T1 between the second thickness T2 and the first thickness T1 within the above range, the above technical solution reasonably sets the second thickness T2 of the second part 2322 based on the first thickness T1 of the main body 231. This allows the second part 2322 to meet good structural strength while avoiding excessive impact on the energy density of the battery cell 7 to a certain extent.

[0181] Furthermore, the second thickness T2 and the first thickness T1 satisfy the relationship: 1 ≤ T2 / T1 ≤ 1.8. As an example, the ratio T2 / T1 between the second thickness T2 and the first thickness T1 can be, but is not limited to, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, etc.

[0182] In some embodiments, the second thickness T2 satisfies the relationship: 1mm ≤ T2 ≤ 1.5mm. As an example, the second thickness T2 can be, but is not limited to, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, or 1.5mm.

[0183] In some embodiments, the first connecting portion 232 further includes a third portion 2323, which is connected between the first portion 2321 and the second portion 2322. The first portion 2321, the second portion 2322 and the third portion 2323 together define the first recess 233.

[0184] For example, the third portion 2323 may extend in a direction perpendicular to the thickness direction X of the wall portion 11. The first connecting portion 232 may be formed by bending the first portion 2321, the second portion 2322 and the third portion 2323, or the first connecting portion 232 may be formed by stamping the first portion 2321, the second portion 2322 and the third portion 2323.

[0185] The introduction of the third part 2323 can increase the size of the first recess 233 in the direction perpendicular to the thickness direction X of the wall 11, thereby increasing the accommodating volume of the first recess 233 and further improving the effect on the fluidity of the molten pool.

[0186] In some examples, the first part 2321, the second part 2322, and the third part 2323 are integrally molded structures. On the one hand, this eliminates the need for additional joining processes to connect the first part 2321, the second part 2322, and the third part 2323, simplifying the manufacturing process. On the other hand, compared to connecting the first part 2321, the second part 2322, and the third part 2323 through additional joining processes, the integral structure provides a higher degree of connection strength.

[0187] In the example where the first connecting portion 232 includes the first protrusion 234, at least a portion of the third portion 2323 protrudes from the side surface of the main body portion 231 facing the wall portion 11 to form the first protrusion 234. The side surface of the portion of the third portion 2323 protruding from the side surface of the main body portion 231 facing the wall portion 11 serves as the abutting surface 235 and abuts against the wall portion 11. Since the third portion 2323 extends in a direction perpendicular to the thickness direction X of the wall portion 11, the area of ​​the abutting surface 235 can be increased, thereby improving the stability of the abutment between the first connecting portion 232 and the wall portion 11.

[0188] In some embodiments, the surface of the third portion 2323 facing away from the wall portion 11 has a second dimension W2 in a direction perpendicular to the thickness direction X of the wall portion 11, and the first thickness T1 and the second dimension W2 of the main body portion 231 satisfy the relationship: 0.1≤W2 / T1≤7.

[0189] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231. The second dimension W2 of the surface of the third part 2323 facing away from the wall part 11 in the direction perpendicular to the thickness direction X of the wall part 11 can be understood as the dimension of the bottom wall of the first recess 233 in the direction perpendicular to the thickness direction X of the wall part 11.

[0190] As an example, the ratio W2 / T1 between the second dimension W2 and the first thickness T1 can be, but is not limited to, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, etc.

[0191] When the first thickness T1 of the main body 231 is constant, the larger the second dimension W2 of the surface of the third part 2323 facing away from the wall part 11 in the direction perpendicular to the thickness direction X of the wall part 11, the larger the volume of the first recess 233 will be. At the same time, the larger the space occupied by the third part 2323 will be, the greater the impact on the energy density of the battery cell 7 will be, that is, it will easily lead to a decrease in the energy density of the battery cell 7. Similarly, the smaller the second dimension W2 is, the smaller the volume of the first recess 233 will be, and the smaller the impact on the energy density of the battery cell 7 will be.

[0192] The third part 2323, on its surface facing away from the wall 11, has a second dimension W2 in a direction perpendicular to the thickness direction X of the wall 11. The first thickness T1 of the main body 231 must also be fully considered. If the first thickness T1 of the main body 231 is too large and the second dimension W2 is too small, the overall design of the third part 2323 will be too difficult; if the first thickness T1 of the main body 231 is too small and the second dimension W2 is too large, the overall structural stability of the first connecting part 232 will be weak.

[0193] Thus, by setting the ratio W2 / T1 between the second dimension W2 and the first thickness T1 within the aforementioned range, and reasonably setting the surface of the third part 2323 facing away from the wall part 11 to have the second dimension W2 in a direction perpendicular to the thickness direction X of the wall part 11 based on the first thickness T1 of the main body 231, it is possible to ensure that the accommodating volume of the first recess 233 meets the requirements while avoiding excessive influence of the third part 2323 on the energy density of the battery cell 7 to a certain extent.

[0194] Furthermore, the second dimension W2 and the first thickness T1 satisfy the relationship: 0.2 ≤ W2 / T1 ≤ 5. As an example, the ratio W2 / T1 between the second dimension W2 and the first thickness T1 can be, but is not limited to, 0.2, 0.6, 1.2, 1.6, 2, 2.2, 2.6, 3, 3.2, 3.6, 4, 4.2, 4.6, 5, etc.

[0195] In some embodiments, the second dimension W2 satisfies the relationship: 1mm ≤ W2 ≤ 2mm. As an example, the second dimension W2 can be, but is not limited to, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, or 2mm.

[0196] In some embodiments, the third portion 2323 has a third dimension W3 on one side surface facing the wall portion 11 in a direction perpendicular to the thickness direction X of the wall portion 11, and the first thickness T1 and the third dimension W3 of the main body portion 231 satisfy the relationship: 0.25≤W3 / T1≤10.

[0197] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231. The third portion 2323 has a third dimension W3 on the side surface facing the wall portion 11 in a direction perpendicular to the thickness direction X of the wall portion 11, which can be understood as the extension dimension of the third portion 2323 in the direction perpendicular to the thickness direction X of the wall portion 11.

[0198] As an example, the ratio W3 / T1 between the third dimension W3 and the first thickness T1 can be, but is not limited to, 0.25, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, etc.

[0199] When the first thickness T1 of the main body 231 is constant, the larger the third dimension W3 of the surface of the third part 2323 facing the wall 11 in the direction perpendicular to the thickness direction X of the wall 11, the larger the dimension of the first connecting part 232 in the direction perpendicular to the thickness direction X of the wall 11, resulting in higher overall structural stability of the first connecting part 232. Simultaneously, the larger the space occupied by the first connecting part 232, the greater its impact on the energy density of the battery cell 7, potentially leading to a decrease in the energy density of the battery cell 7. Similarly, the smaller the third dimension W3, the worse the overall structural stability of the first connecting part 232, and the smaller its impact on the energy density of the battery cell 7.

[0200] The third part 2323, facing the wall 11, has a third dimension W3 in a direction perpendicular to the thickness direction X of the wall 11. The first thickness T1 of the main body 231 must also be fully considered. If the first thickness T1 of the main body 231 is too large and the third dimension W3 is too small, the overall design of the third part 2323 will be too difficult; if the first thickness T1 of the main body 231 is too small and the third dimension W3 is too large, the overall structural consistency of the fastener 23 will be poor.

[0201] Thus, by setting the ratio W3 / T1 between the third dimension W3 and the first thickness T1 within the aforementioned range, and reasonably setting the third part 2323 to have a third dimension W3 on the side surface of the wall part 11 facing the wall part 11 based on the first thickness T1 of the main body 231, it is possible to ensure that the overall structural stability of the first connecting part 232 meets the requirements, while to a certain extent avoiding excessive influence of the third part 2323 on the energy density of the battery cell 7.

[0202] Furthermore, the third dimension W3 and the first thickness T1 satisfy the relationship: 2≤W3 / T1≤3. As an example, the ratio W3 / T1 between the third dimension W3 and the first thickness T1 can be, but is not limited to, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, etc.

[0203] In some embodiments, the third dimension W3 satisfies the relationship: 1mm ≤ W3 ≤ 1.5mm. As an example, the third dimension W3 can be, but is not limited to, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, or 1.5mm.

[0204] In some examples, the first connecting portion 232 includes a first protrusion 234, and a third portion 2323 protrudes from the side surface of the main body 231 facing the wall portion 11 to form the first protrusion 234. The third portion 2323 has a third dimension W3 on the side surface facing the wall portion 11 in a direction perpendicular to the thickness direction X of the wall portion 11, that is, the dimension of the side surface of the first protrusion 234 and the third portion 2323 facing the wall portion 11 in a direction perpendicular to the thickness direction X of the wall portion 11. The larger the third dimension W3 is, the larger the contact area 235 between the first protrusion 234 and the wall portion 11 is, and the better the stability of the contact between the first connecting portion 232 and the wall portion 11 is. Thus, by setting the ratio W3 / T1 between the third dimension W3 and the first thickness T1 within the above range, it is possible to meet the requirements for the stability of the contact between the first connecting portion 232 and the wall portion 11 while avoiding excessive influence of the third portion 2323 on the energy density of the battery cell 7 to a certain extent.

[0205] In some embodiments, the first thickness T1 of the main body 231 and the third thickness T3 of the third part 2323 satisfy the relationship: 0.4≤T3 / T1≤2.5.

[0206] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231, and the third thickness T3 of the third part 2323 can be understood as the thickness of the sheet constituting the third part 2323.

[0207] As an example, the ratio T3 / T1 between the third thickness T3 and the first thickness T1 can be, but is not limited to, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 2, 2.2, 2.5, etc.

[0208] When the first thickness T1 of the main body 231 is constant, the larger the third thickness T3 of the third part 2323, the better the structural strength of the third part 2323; at the same time, the larger the space occupied by the third part 2323, the greater its impact on the energy density of the battery cell 7, that is, it is more likely to cause a decrease in the energy density of the battery cell 7. Similarly, the smaller the third thickness T3 of the third part 2323, the worse the structural strength of the third part 2323, and the smaller its impact on the energy density of the battery cell 7.

[0209] The setting of the third thickness T3 of the third part 2323 also needs to fully consider the first thickness T1 of the main body 231. If the first thickness T1 of the main body 231 is too large and the third thickness T3 is too small, or if the first thickness T1 of the main body 231 is too small and the third thickness T3 is too large, the overall structural stability of the fastener 23 will be weak and the structural consistency will be poor.

[0210] Thus, by setting the ratio T3 / T1 between the third thickness T3 and the first thickness T1 within the above range, the third thickness T3 of the third part 2323 is reasonably set based on the first thickness T1 of the main body 231. This allows the third part 2323 to meet good structural strength while avoiding excessive impact of the third part 2323 on the energy density of the battery cell 7 to a certain extent.

[0211] Furthermore, the third thickness T3 and the first thickness T1 satisfy the relationship: 0.75 ≤ T3 / T1 ≤ 1.2. As an example, the ratio T3 / T1 between the third thickness T3 and the first thickness T1 can be, but is not limited to, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.1, 1.12, 1.14, 1.16, 1.18, 2, etc.

[0212] In some embodiments, the third thickness T3 satisfies the relationship: 0.6mm ≤ T3 ≤ 1mm. As an example, the third thickness T3 can be, but is not limited to, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1mm.

[0213] In some embodiments, the first connecting portion 232 further includes a first arc surface 237, which connects the side surface of the third portion 2323 facing away from the wall portion 11 and the side surface of the first portion 2321 facing the first recess 233.

[0214] On the one hand, as the molten pool flows and spreads along the inner wall of the first recess 233, the introduction of the first arc surface 237 enables the molten pool to flow more smoothly and evenly, thereby further improving the flow performance of the molten pool and thus further improving the welding quality. On the other hand, the first arc surface 237 also helps to reduce the risk of stress concentration between the first part 2321 and the third part 2323, which can improve the connection stability between the terminal assembly 20 and the wall 11, thereby helping to further improve the reliability of the battery cell 7.

[0215] In some embodiments, the first arc R1 of the first arc surface 237 satisfies the relationship: 0.25mm≤R1≤5mm.

[0216] As an example, the first arc R1 of the first arc surface 237 can be, but is not limited to, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc.

[0217] The above technical solution sets the first arc R1 of the first arc surface 237 within the above range, so that the first arc surface 237 can satisfy its own structural effect while reducing the difficulty of setting the first arc surface 237.

[0218] Furthermore, the first radian R1 of the first arc surface 237 satisfies the relationship: 0.5mm ≤ R1 ≤ 2mm. As an example, the ratio T3 / T1 between the third thickness T3 and the first thickness T1 can be, but is not limited to, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, etc.

[0219] In some embodiments, the first connecting portion 232 further includes a second arc surface 238, which connects the third portion 2323 on the side surface facing away from the wall portion 11 and the second portion 2322 on the side surface facing the first recess 233.

[0220] The second arc surface 238 helps reduce the risk of stress concentration between the second part 2322 and the third part 2323, and can improve the connection stability between the terminal assembly 20 and the wall 11, thereby helping to further improve the reliability of the battery cell 7.

[0221] In some embodiments, the second arc R2 of the second arc surface 238 satisfies the relationship: 0.5mm≤R2≤6mm.

[0222] As an example, the second arc R2 of the second arc surface 238 can be, but is not limited to, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, etc.

[0223] The above technical solution, by setting the second arc R2 of the second arc surface 238 within the above range, enables the second arc surface 238 to reduce the risk of stress concentration between the second part 2322 and the third part 2323, while also reducing the difficulty of setting the second arc surface 238.

[0224] Furthermore, the second radii R2 of the second arc surface 238 satisfy the relationship: 1mm ≤ R2 ≤ 3mm. As an example, the ratio T3 / T1 between the third thickness T3 and the first thickness T1 can be, but is not limited to, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, etc.

[0225] In some embodiments, the first connecting portion 232 further includes a third arc surface, which connects the side surface of the third portion 2323 facing the wall portion 11 and the side surface of the first portion 2321 facing away from the first recess 233.

[0226] In some embodiments, the first connecting portion 232 further includes a fourth arc surface, the third arc surface being connected between the side surface of the third portion 2323 facing the wall portion 11 and the side surface of the second portion 2322 facing away from the first recess 233.

[0227] It should be noted that the third and fourth arc surfaces have the same structural principle as the first arc surface 237 and the second arc surface 238. For a detailed description of the third and fourth arc surfaces, please refer to the detailed description of the first arc surface 237 and the second arc surface 238 mentioned above. They will not be repeated here.

[0228] In some embodiments, a groove 112 is provided on the outer side of the wall portion 11, and at least a portion of the first connecting portion 232 is accommodated in the groove 112.

[0229] At least a portion of the first connecting portion 232 is accommodated in the groove 112. This can be understood as a portion of the first connecting portion 232 being accommodated in the groove 112, or the entire first connecting portion 232 being accommodated in the groove 112.

[0230] In some examples, the wall 11 is formed with grooves 112 by a stamping process.

[0231] By introducing a groove 112 to accommodate the first connecting part 232, the occupation of the first connecting part 232 on the external space of the battery cell 7 can be effectively reduced, thereby helping to improve the energy density of the battery cell 7.

[0232] In some embodiments, the main body 231 includes a fourth portion 2311 and a fifth portion 2312, the fifth portion 2312 being connected to the fourth portion 2311 and the first connecting portion 232, the fourth portion 2311 being embedded inside the insulating member 22, and the fifth portion 2312 being exposed outside the insulating member 22.

[0233] The fourth part 2311 is embedded inside the insulating member 22. The fourth part 2311 can be understood as the part that is fixedly connected to the main body 231 and the insulating member 22. The fifth part 2312 extends from one end of the fourth part 2311 and is exposed outside the insulating member 22. The fifth part 2312 is used to connect the first connecting part 232.

[0234] The fifth part 2312 can be detachably connected to the fourth part 2311, or it can be integrally formed on the fourth part 2311. The fifth part 2312 can be directly connected to the fourth part 2311, or it can be constrained to the fourth part 2311 by other components. As an example, the connection method between the fifth part 2312 and the fourth part 2311 can be, but is not limited to, bolt connection, welding, riveting, bonding, or snap-fit.

[0235] In some examples, the fourth part 2311 and the fifth part 2312 are integrally molded structures. On the one hand, there is no need to connect the fourth part 2311 and the fifth part 2312 through an additional connecting process, simplifying the manufacturing process. At the same time, compared to connecting the fourth part 2311 and the fifth part 2312 through an additional connecting process, the integral structure of the fourth part 2311 and the fifth part 2312 has a higher connection strength.

[0236] The above technical solution, on the one hand, can improve the connection stability between the fixing member 23 and the insulating member 22 by embedding the fourth part 2311 inside the insulating member 22; on the other hand, by exposing the fifth part 2312 outside the insulating member 22, it can not only simplify the manufacturing difficulty of the first connecting part 232, but also reduce the risk of interference between the insulating member 22 and the first connecting part 232 affecting the connection effect between the first connecting part 232 and the wall part 11.

[0237] In some embodiments, the end face of the portion of the first connecting portion 232 surrounding the outside of the first recess 233 on the side away from the wall portion 11 in the thickness direction X is flush with the surface of the fifth portion 2312 on the side away from the wall portion 11 in the thickness direction X, which can improve the overall structural consistency of the fastener 23.

[0238] In some embodiments, the housing 10 includes a housing 10a and an end cap 10b, the housing 10a having an opening, the end cap 10b closing the opening, and the end cap 10b being configured as a wall portion 11.

[0239] For example, end cap 10b refers to a component that covers the opening of housing 10a to isolate the internal environment of battery cell 7 from the external environment. Optionally, the shape of end cap 10b can be adapted to the shape of housing 10a to fit housing 10a. Optionally, end cap 10b can be made of a material with a certain hardness and strength (such as aluminum alloy), so that end cap 10b is not easily deformed when subjected to compression and impact, so that battery cell 7 can have higher structural strength and improved reliability. Functional components such as terminal groups can be provided on end cap 10b. The material of end cap 10b can also be various. For example, end cap 10b can be made of, but is not limited to, metal or non-metal materials. For example, metal materials can be copper, aluminum, or stainless steel; non-metal materials can be polyethylene, polypropylene, or polyvinyl chloride.

[0240] The housing 10a is a component used to cooperate with the end cap 10b to form the internal environment of the battery cell 7. This internal environment can accommodate the electrode assembly 30, electrolyte, and other components. The housing 10a and the end cap 10b can be independent components. An opening can be provided on the housing 10a, and the end cap 10b closes the opening to form the internal environment of the battery cell 7. Optionally, the end cap 10b and the housing 10a can be integrated. Specifically, the end cap 10b and the housing 10a can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 10a, the end cap 10b closes the housing 10a. The housing 10a can have various shapes and sizes, such as cuboid, cylindrical, or hexagonal prism. Specifically, the shape of the housing 10a can be determined according to the specific shape and size of the electrode assembly 30. The shell 10a can be made of various materials. For example, the shell 10a can be made of metal or non-metal materials, such as copper, aluminum or stainless steel; and non-metal materials can be polyethylene, polypropylene or polyvinyl chloride.

[0241] Optionally, the end cap 10b can be detachably connected to the housing 10a, or it can be integrally mounted on the housing 10a. The end cap 10b can be directly connected to the housing 10a, or it can be constrained to the housing 10a by other components. As an example, the connection method between the end cap 10b and the housing 10a can be, but is not limited to, welding, riveting, or bonding.

[0242] Figure 9 is a structural schematic diagram of another battery cell 7 provided in some embodiments of this application, Figure 10 is a cross-sectional structural schematic diagram along BB in Figure 9, and Figure 11 is a partially enlarged structural schematic diagram of the structure shown in Figure 10.

[0243] Referring again to Figures 9 and 10, in some embodiments, the battery cell 7 further includes an electrode assembly 30, which is housed within the housing 10a. The end cap 10b includes a cap body 40, a second connecting portion 50, and a second recess 60. The second connecting portion 50 is connected to the cap body 40, and the second recess 60 is disposed on the side of the second connecting portion 50 facing away from the electrode assembly 30. At least a portion of the second connecting portion 50 surrounds the outside of the second recess 60 and is welded to the housing 10a.

[0244] The second connecting part 50 can be detachably connected to the cover body 40, or it can be integrally formed on the cover body 40. The second connecting part 50 can be directly connected to the cover body 40, or it can be constrained to the cover body 40 by other components. As an example, the connection method between the second connecting part 50 and the cover body 40 can be, but is not limited to, bolt connection, welding, riveting, bonding, or snap-fit.

[0245] In some examples, the second connecting portion 50 and the cover body 40 are integrally formed. On the one hand, this eliminates the need for additional connecting processes to connect the second connecting portion 50 and the cover body 40, simplifying the manufacturing process. On the other hand, compared to connecting the second connecting portion 50 and the cover body 40 through additional connecting processes, the integral structure of the second connecting portion 50 and the cover body 40 provides a higher degree of connection strength.

[0246] The second recess 60 may be an annular groove surrounding the outer side of the cover body 40. At least a portion of the second connecting portion 50 surrounds the outer side of the second recess 60. This can be understood as a portion of the second connecting portion 50 surrounding the outer side of the second recess 60, or all of the second connecting portion 50 surrounding the outer side of the second recess 60.

[0247] The portion of the second connecting part 50 surrounding the outer side of the second recess 60 will form a weld mark after being welded to the housing 10a, thereby achieving a fixed connection between the end cap 10b and the housing 10a. Optionally, the welding method between the second connecting part 50 and the wall part 11 can be, but is not limited to, plasma welding, electron beam welding, brazing, pressure welding, etc.

[0248] In the welding process between the second connecting part 50 and the housing 10a, the portion of the second connecting part 50 surrounding the second recess 60 is heated and melts to form a molten pool, which can release the welding thermal stress of this part to a certain extent, thus improving the connection reliability between the second connecting part 50 and the housing 10a.

[0249] On the other hand, by introducing the second recess 60, the material of the second connecting portion 50 can be reduced, especially the material adjacent to the portion of the second connecting portion 50 surrounding the outside of the second recess 60. This allows some of the heat generated during the welding of the portion of the second connecting portion 50 surrounding the outside of the second recess 60 with the housing 10a to be transferred to the air inside the second recess 60, rather than directly to the material adjacent to the portion of the second connecting portion 50 surrounding the outside of the second recess 60 and melting that material. This reduces the overall heat input of the second connecting portion 50, thereby reducing welding thermal stress to a certain extent and reducing the generation of welding cracks.

[0250] On the other hand, after the portion of the second connecting part 50 surrounding the outer side of the second recess 60 melts upon heating to form a molten pool, the molten pool can spread along the inner wall of the second recess 60 under the action of gravity, thereby giving the molten pool good fluidity and reducing the generation of defects such as welding porosity, thus improving welding quality. In this way, the connection stability between the end cap 10b and the housing 10a can be improved, thereby effectively improving the reliability of the battery cell 7.

[0251] It should be noted that the second connecting part 50 and the first connecting part 232 have the same principle structure. The structural features on the first connecting part 232 can be applied to the second connecting part 50 and achieve the same or similar technical effects. For the specific structural details, please refer to the description of the first connecting part 232 above, which will not be repeated here.

[0252] In some embodiments, the second connecting portion 50 includes a second protrusion 70, the position of which corresponds to the position of the second recess 60, and the second protrusion 70 protrudes from the side surface of the cover body 40 facing the electrode assembly 30.

[0253] The position of the second protrusion 70 corresponds to the position of the second recess 60. It can be understood that the projection of the second protrusion 70 on the thickness direction X of the wall portion 11 and the projection of the second recess 60 on the thickness direction X of the wall portion 11 at least partially overlap.

[0254] In some examples, the second recess 60 can be formed by stamping on the second connecting portion 50 to simultaneously form a second protrusion 70 protruding from the side surface of the cover body 40 facing the electrode assembly 30, thereby simplifying the overall manufacturing process.

[0255] The second protrusion 70 protrudes from the surface of the cover body 40 facing the electrode assembly 30, enabling the second connecting part 50 to form a cantilever structure. During the welding process between the second connecting part 50 and the housing 10a, the second connecting part 50 can release welding thermal stress through its own micro-transformation, thereby further improving the welding quality between the end cover 10b and the housing 10a, and further improving the reliability of the battery cell 7.

[0256] It should be noted that the second protrusion 70 and the first protrusion 234 have the same principle structure. The structural features on the first protrusion 234 can be applied to the second protrusion 70 and achieve the same or similar technical effects. For the specific structural details, please refer to the description of the first protrusion 234 above, which will not be repeated here.

[0257] Referring again to Figures 7 and 8, this embodiment of the application also provides a terminal assembly 20. The terminal assembly 20 includes an electrode terminal 21, an insulating member 22, and a fixing member 23. The insulating member 22 at least partially surrounds and is connected to the electrode terminal 21. The fixing member 23 includes a main body portion 231, a first connecting portion 232, and a first recess 233. The main body portion 231 is fixed to the insulating member 22. The first connecting portion 232 is connected to the main body portion 231. The first recess 233 is disposed on one side of the first connecting portion 232. At least a portion of the first connecting portion 232 surrounds the outside of the first recess 233 and is used for welding to the wall portion 11 of the outer casing 10 of the battery cell 7. The first recess 233 is located on the side of the first connecting portion 232 opposite to the wall portion 11.

[0258] Exemplarily, the housing 10 is a component used to form the internal environment of the battery cell 7. The formed internal environment can accommodate the electrode assembly 30, electrolyte, and other components. Optionally, the housing 10 can be, but is not limited to, made of metallic or non-metallic materials. For example, metallic materials can be copper, aluminum, or stainless steel; non-metallic materials can be polyethylene, polypropylene, or polyvinyl chloride.

[0259] The battery cell 7 may also include an electrode assembly 30, which is housed within the casing 10a. The electrode assembly 30 is the component in the battery cell 7 where the electrochemical reaction occurs. The electrode assembly 30 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body 231 of the electrode assembly 30, while the portions of the positive and negative electrode sheets without active material each constitute a tab. The positive and negative tabs may be located together at one end of the main body 231 or separately at both ends of the main body 231. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs connect to the electrode terminals 21 to form a current loop.

[0260] The outer side of the wall portion 11 refers to the side of the wall portion 11 facing away from the electrode assembly 30, and the outer side of the first recess 233 refers to the side of the first recess 233 that is away from the main body portion 231 in a direction perpendicular to the thickness direction X of the wall portion 11.

[0261] The insulating member 22 is used to insulate the electrode terminal 21 and the fixing member 23, which is used to fix the electrode terminal 21 to the wall portion 11. As an example, the insulating member 22 is inserted into the electrode terminal 21.

[0262] Optionally, the insulating component 22 may be, but is not limited to, made of insulating materials such as polyethylene, polypropylene, polyvinyl chloride, or rubber. The fastener 23 may be, but is not limited to, made of materials such as copper, copper alloy, aluminum, aluminum alloy, or steel.

[0263] The main body 231 can be detachably connected to the insulating member 22, or it can be integrally formed on the insulating member 22. The main body 231 can be directly connected to the insulating member 22, or it can be constrained to the insulating member 22 by other components. As an example, the connection method between the main body 231 and the insulating member 22 can be, but is not limited to, bolt connection, welding, riveting, bonding, or snap-fit.

[0264] In some examples, the insulating element 22 is formed on the main body 231 by injection molding.

[0265] The first connecting part 232 can be detachably connected to the main body 231, or it can be integrally provided on the main body 231. The first connecting part 232 can be directly connected to the main body 231, or it can be constrained to the main body 231 by other components. As an example, the connection method between the first connecting part 232 and the main body 231 can be, but is not limited to, bolt connection, welding, riveting, bonding, or snap-fit.

[0266] In some examples, the first connecting portion 232 and the main body portion 231 are integrally formed. On the one hand, there is no need to connect the first connecting portion 232 and the main body portion 231 through an additional connecting process, simplifying the manufacturing process. At the same time, compared with connecting the first connecting portion 232 and the main body portion 231 through an additional connecting process, the integral structure of the first connecting portion 232 and the main body portion 231 has a higher connection strength.

[0267] The first recess 233 may be an annular groove surrounding the outside of the main body 231. At least a portion of the first connecting portion 232 surrounds the outside of the first recess 233. This can be understood as a portion of the first connecting portion 232 surrounding the outside of the first recess 233, or all of the first connecting portion 232 surrounding the outside of the first recess 233.

[0268] The portion of the first connecting part 232 surrounding the outside of the first recess 233 is welded to the wall part 11 to form a welded part, thereby achieving a fixed connection between the fastener 23 and the wall part 11. Optionally, the welding method between the first connecting part 232 and the wall part 11 can be, but is not limited to, plasma welding, electron beam welding, brazing, pressure welding, etc.

[0269] In the welding process between the first connecting part 232 and the wall part 11, the portion of the first connecting part 232 surrounding the outside of the first recess 233 is heated and melts to form a molten pool, which can release the welding thermal stress of this part to a certain extent, thus improving the connection reliability between the first connecting part 232 and the wall part 11.

[0270] On the other hand, by introducing the first recess 233, the material of the first connecting portion 232 can be reduced, especially the material adjacent to the portion of the first connecting portion 232 surrounding the outside of the first recess 233. This allows part of the heat generated by welding the portion of the first connecting portion 232 surrounding the outside of the first recess 233 with the wall portion 11 to be transferred to the air inside the first recess 233, rather than directly to the material adjacent to the portion of the first connecting portion 232 surrounding the outside of the first recess 233 and melting that material. This reduces the overall heat input of the first connecting portion 232, thereby reducing welding thermal stress to a certain extent and reducing the generation of welding cracks.

[0271] On the other hand, after the portion of the first connecting part 232 surrounding the outside of the first recess 233 melts upon heating to form a molten pool, the molten pool can spread along the inner wall of the first recess 233 under the action of gravity, thereby giving the molten pool good fluidity, reducing the generation of defects such as welding porosity, and thus improving welding quality. In this way, the connection stability between the terminal assembly 20 and the wall 11 can be improved, thereby effectively improving the reliability of the battery cell 7.

[0272] In some embodiments, the first thickness T1 of the main body 231 and the fourth thickness T4 of the first portion 2321 satisfy the relationship: 0.5 ≤ T4 / T1 ≤ 2. The first portion 2321 is the part of the first connecting portion 232 that surrounds the outside of the first recess 233.

[0273] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231, and the fourth thickness T4 of the first part 2321 can be understood as the thickness of the sheet constituting the first part 2321 between the first connecting part 232 and the wall part 11.

[0274] As an example, the ratio T4 / T1 between the fourth thickness T4 and the first thickness T1 can be, but is not limited to, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2, etc.

[0275] When the first thickness T1 of the main body 231 is constant, the larger the fourth thickness T4 of the first part 2321, the more molten pools can be formed during the welding process of the first part 2321, resulting in better welding strength between the first connecting part 232 and the wall part 11. At the same time, the larger the space occupied by the first part 2321, the greater the impact on the energy density of the battery cell 7, which can easily lead to a decrease in the energy density of the battery cell 7. Similarly, the smaller the fourth thickness T4 of the first part 2321, the fewer molten pools can be formed during the welding process of the first part 2321, and the smaller the impact on the energy density of the battery cell 7.

[0276] The setting of the fourth thickness T4 in the first part 2321 also needs to fully consider the first thickness T1 of the main body 231. If the first thickness T1 of the main body 231 is too large and the fourth thickness T4 is too small, or if the first thickness T1 of the main body 231 is too small and the fourth thickness T4 is too large, the overall structural stability of the fastener 23 will be weak and the structural consistency will be poor.

[0277] Thus, by setting the ratio T4 / T1 between the fourth thickness T4 and the first thickness T1 within the above range, the above-mentioned technical solution reasonably sets the fourth thickness T4 of the first part 2321 based on the first thickness T1 of the main body 231. This can ensure good welding strength between the first connecting part 232 and the wall part 11, while avoiding excessive influence of the first part 2321 on the energy density of the battery cell 7 to a certain extent.

[0278] Furthermore, the fourth thickness T4 and the first thickness T1 satisfy the relationship: 0.75 ≤ T4 / T1 ≤ 1.5. As an example, the ratio T4 / T1 between the fourth thickness T4 and the first thickness T1 can be, but is not limited to, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.1, 1.2, 1.3, 1.4, 1.5, etc.

[0279] In some embodiments, the fourth thickness T4 satisfies the relationship: 0.5mm ≤ T4 ≤ 1mm. As an example, the fourth thickness T4 can be, but is not limited to, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1mm.

[0280] In some embodiments, in the thickness direction X of the wall portion 11, there is a second distance H2 between the end face of the first portion 2321 away from the bottom wall of the first recess 233 and the bottom wall, and the first thickness T1 and the second distance H2 of the main body portion 231 satisfy the relationship: 0.25≤H2 / T1≤6;

[0281] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231. The second distance H2 between the end face of the first portion 2321 away from the bottom wall of the first recess 233 and the bottom wall can be understood as the height by which the first portion 2321 protrudes from the bottom wall in the thickness direction X of the wall portion 11.

[0282] As an example, the ratio H2 / T1 between the second distance H2 and the first thickness T1 can be, but is not limited to, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, 4, 4.5, 5, 5.5, 6, etc.

[0283] When the first thickness T1 of the main body 231 is constant, the larger the second distance H2 between the end face of the first part 2321 away from the bottom wall of the first recess 233 and the bottom wall, the more molten pools can be formed in the first part 2321 during welding, resulting in better welding strength between the first connecting part 232 and the wall part 11. At the same time, the larger the space occupied by the first part 2321, the greater the impact on the energy density of the battery cell 7, which can easily lead to a decrease in the energy density of the battery cell 7. Similarly, the smaller the second distance H2, the fewer molten pools can be formed in the first part 2321 during welding, and the smaller the impact on the energy density of the battery cell 7.

[0284] The setting of the second distance H2 between the end face of the first part 2321 away from the bottom wall of the first recess 233 and the bottom wall also needs to fully consider the first thickness T1 of the main body 231. If the first thickness T1 of the main body 231 is too large and the second distance H2 is too small, it will make the overall setting of the first part 2321 too difficult; if the first thickness T1 of the main body 231 is too small and the second distance H2 is too large, the overall structural consistency of the fastener 23 will be poor.

[0285] Thus, by setting the ratio H2 / T1 between the second distance H2 and the first thickness T1 within the above range, and reasonably setting the second distance H2 between the end face of the first part 2321 away from the bottom wall of the first recess 233 and the bottom wall based on the first thickness T1 of the main body 231, the above-mentioned technical solution can ensure good welding strength between the first connecting part 232 and the wall part 11, while avoiding excessive influence of the first part 2321 on the energy density of the battery cell 7 to a certain extent.

[0286] Furthermore, the second distance H2 and the first thickness T1 satisfy the relationship: 0.5 ≤ H2 / T1 ≤ 3. As an example, the ratio H2 / T1 between the second distance H2 and the first thickness T1 can be, but is not limited to, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.5, 3, etc.

[0287] In some embodiments, the second distance H2 satisfies the relationship: 0.3mm ≤ H2 ≤ 1mm. As an example, the second distance H2 can be, but is not limited to, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1mm.

[0288] In some embodiments, in the thickness direction X of the wall portion 11, there is a third distance H3 between the side end face of the first portion 2321 away from the bottom wall of the first recess 233 and the side surface of the first connecting portion 232 opposite to the first recess 233, and the first thickness T1 and the third distance H3 of the main body portion 231 satisfy the relationship: 0.5≤H3 / T1≤7.

[0289] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231. The third distance H3 between the end face of the first portion 2321 away from the bottom wall of the first recess 233 and the surface of the first connecting portion 232 opposite to the first recess 233 can be understood as the dimension of the first portion 2321 in the thickness direction X of the wall portion 11.

[0290] As an example, the ratio H3 / T1 between the third distance H3 and the first thickness T1 can be, but is not limited to, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, 4, 4.5, 5, 5.5, 6, 6.5, 7, etc.

[0291] When the first thickness T1 of the main body 231 is constant, the larger the third distance H3 between the end face of the first part 2321 away from the bottom wall of the first recess 233 and the surface of the first connecting part 232 facing away from the first recess 233, the better the structural strength of the first part 2321. Simultaneously, the larger the space occupied by the first part 2321, the greater its impact on the energy density of the battery cell 7, meaning it is more likely to cause a decrease in the energy density of the battery cell 7. Similarly, the smaller the third distance H3, the worse the structural strength of the first part 2321, and the smaller its impact on the energy density of the battery cell 7.

[0292] The setting of the third distance H3 between the end face of the first part 2321 away from the bottom wall of the first recess 233 and the surface of the first connecting part 232 away from the first recess 233 also needs to fully consider the first thickness T1 of the main body 231. If the first thickness T1 of the main body 231 is too large and the third distance H3 is too small, it will make the overall setting of the first part 2321 too difficult; if the first thickness T1 of the main body 231 is too small and the third distance H3 is too large, the overall structural consistency of the fastener 23 will be poor.

[0293] Thus, by setting the ratio H3 / T1 between the third distance H3 and the first thickness T1 within the aforementioned range, and reasonably setting the third distance H3 between the end face of the first part 2321 away from the bottom wall of the first recess 233 and the side surface of the first connecting part 232 facing away from the first recess 233 based on the first thickness T1 of the main body 231, it is possible to ensure that the first part 2321 meets good structural strength while avoiding excessive influence of the first part 2321 on the energy density of the battery cell 7 to a certain extent.

[0294] Furthermore, the third distance H3 and the first thickness T1 satisfy the relationship: 1 ≤ H3 / T1 ≤ 5. As an example, the ratio H3 / T1 between the third distance H3 and the first thickness T1 can be, but is not limited to, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc.

[0295] In some embodiments, the third distance H3 satisfies the relationship: 1mm ≤ H3 ≤ 2mm. As an example, the third distance H3 can be, but is not limited to, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or 2mm.

[0296] In some embodiments, the side surface of the first portion 2321 facing away from the first recess 233 has a fourth dimension W4 in the thickness direction X of the wall portion 11, and the first thickness T1 and the fourth dimension W4 of the main body portion 231 satisfy the relationship: 0.3≤W4 / T1≤5;

[0297] For example, the fastener 23 may be a sheet or formed by bending a sheet. The first thickness T1 of the main body 231 can be understood as the thickness of the sheet constituting the main body 231. The fourth dimension W4 of the side surface of the first portion 2321 facing away from the first recess 233 in the thickness direction X of the wall portion 11 can be understood as the dimension of the contact surface of the first portion 2321 that abuts against the wall portion 11 in the thickness direction X of the wall portion 11.

[0298] As an example, the ratio W4 / T1 between the fourth dimension W4 and the first thickness T1 can be, but is not limited to, 0.3, 0.5, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.25, 3.5, 3.75, 4, 4.5, 5, etc.

[0299] When the first thickness T1 of the main body 231 is constant, the larger the fourth dimension W4 of the side surface of the first part 2321 facing away from the first recess 233 in the thickness direction X of the wall part 11, the larger the contact surface of the first part 2321 against the wall part 11, resulting in better stability during the welding process of the first connecting part 232 and the wall part 11, and thus better welding quality. At the same time, the larger the space occupied by the first part 2321, the greater the impact on the energy density of the battery cell 7, that is, it is easy to cause the energy density of the battery cell 7 to decrease. Similarly, the smaller the fourth dimension W4, the smaller the contact surface of the first part 2321 against the wall part 11, and the smaller the impact on the energy density of the battery cell 7.

[0300] The setting of the fourth dimension W4 of the side surface of the first part 2321 facing away from the first recess 233 in the thickness direction X of the wall part 11 also needs to fully consider the first thickness T1 of the main body 231. If the first thickness T1 of the main body 231 is too large and the fourth dimension W4 is too small, it will make the overall setting of the first part 2321 too difficult; if the first thickness T1 of the main body 231 is too small and the fourth dimension W4 is too large, the overall structural consistency of the fastener 23 will be poor.

[0301] Thus, by setting the ratio W4 / T1 between the fourth dimension W4 and the first thickness T1 within the aforementioned range, and reasonably setting the fourth dimension W4 of the side surface of the first part 2321 facing away from the first recess 233 in the thickness direction X of the wall part 11 based on the first thickness T1 of the main body 231, it is possible to ensure that the first connecting part 232 and the wall part 11 meet good welding quality while avoiding excessive influence of the first part 2321 on the energy density of the battery cell 7 to a certain extent.

[0302] Furthermore, the fourth dimension W4 and the first thickness T1 satisfy the relationship: 0.5 ≤ W4 / T1 ≤ 2.4. As an example, the ratio W4 / T1 between the fourth dimension W4 and the first thickness T1 can be, but is not limited to, 0.5, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.4, etc.

[0303] In some embodiments, the fourth dimension W4 satisfies the relationship: 0.5mm ≤ W4 ≤ 1.2mm. As an example, the fourth dimension W4 can be, but is not limited to, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, or 1.2mm.

[0304] According to some embodiments of this application, this application also provides a battery, including a battery cell 7 of any of the above schemes.

[0305] According to some embodiments of this application, this application also provides an electrical device including a battery cell 7 of any of the above schemes, the battery cell 7 being used to provide electrical energy.

[0306] To better understand the battery cell 7 provided in the embodiments of this application, based on the same inventive concept, embodiments of the battery cell 7 in practical applications are provided here for illustration.

[0307] This application provides a battery cell 7, which includes a housing 10 and a terminal assembly 20. The housing 10 includes a wall portion 11, and the wall portion 11 has an electrode lead-out hole 111. The terminal assembly 20 includes an electrode terminal 21, an insulating member 22, and a fixing member 23. At least a portion of the electrode terminal 21 is located in the wall portion 11 and covers the electrode lead-out hole 111. The insulating member 22 at least partially surrounds the electrode terminal 21 and is connected to the electrode terminal 21. The fixing member 23 includes a main body portion 231, a first connecting portion 232, and a first recess 233. The main body portion 231 is fixed to the insulating member 22. The first connecting portion 232 is connected to the main body portion 231. The first recess 233 is disposed on the side of the first connecting portion 232 opposite to the wall portion 11 along the thickness direction X. At least a portion of the first connecting portion 232 surrounds the outside of the first recess 233 and is welded to the wall portion 11. The first connecting portion 232 includes a first protrusion 234, the position of which corresponds to the position of the first recess 233. The first protrusion 234 protrudes from the side surface of the main body portion 231 facing the wall portion 11 and abuts against the wall portion 11.

[0308] In the welding process between the first connecting part 232 and the wall part 11, the portion of the first connecting part 232 surrounding the outside of the first recess 233 is heated and melts to form a molten pool, which can release the welding thermal stress of this part to a certain extent, thus improving the connection reliability between the first connecting part 232 and the wall part 11.

[0309] On the other hand, by introducing the first recess 233, the material of the first connecting portion 232 can be reduced, especially the material adjacent to the portion of the first connecting portion 232 surrounding the outside of the first recess 233. This allows part of the heat generated by welding the portion of the first connecting portion 232 surrounding the outside of the first recess 233 with the wall portion 11 to be transferred to the air inside the first recess 233, rather than directly to the material adjacent to the portion of the first connecting portion 232 surrounding the outside of the first recess 233 and melting that material. This reduces the overall heat input of the first connecting portion 232, thereby reducing welding thermal stress to a certain extent and reducing the generation of welding cracks.

[0310] On the other hand, after the portion of the first connecting part 232 surrounding the outside of the first recess 233 melts upon heating to form a molten pool, the molten pool can spread along the inner wall of the first recess 233 under the action of gravity, thereby giving the molten pool good fluidity, reducing the generation of defects such as welding porosity, and thus improving welding quality. In this way, the connection stability between the terminal assembly 20 and the wall 11 can be improved, thereby effectively improving the reliability of the battery cell 7.

[0311] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0312] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A single battery cell, comprising: The outer casing includes a wall portion, wherein the wall portion is provided with electrode lead-out holes; A terminal assembly includes electrode terminals, an insulating member, and a fixing member, wherein at least a portion of the electrode terminals is located in the wall portion and covers the electrode lead-out hole, and the insulating member at least partially surrounds and is connected to the electrode terminals. The fastener includes a main body, a first connecting part, and a first recess. The main body is fixed to the insulating member, the first connecting part is connected to the main body, the first recess is disposed on the side of the first connecting part away from the wall along the thickness direction of the wall, and at least a portion of the first connecting part surrounds the outside of the first recess and is welded to the wall.

2. The battery cell according to claim 1, wherein, The first connecting portion includes a first protrusion, the position of which corresponds to the position of the first recess, the first protrusion protruding from the side surface of the main body facing the wall portion and abutting against the wall portion.

3. The battery cell according to claim 2, wherein, The first distance H1 between the side surface of the first protrusion facing the wall and the side surface of the main body facing the wall and the first thickness T1 of the main body satisfy the relationship: 0.25≤H1 / T1≤4.

4. The battery cell according to any one of claims 1-3, wherein, The first connecting portion includes an abutting surface and a guiding surface. The abutting surface abuts against the wall portion along the thickness direction, and the guiding surface is inclined from one end of the abutting surface toward the side of the abutting surface away from the wall portion. The first connecting portion is welded to the wall portion to form a welded portion, and the end of the guide surface away from the abutment surface extends to the welded portion.

5. The battery cell according to claim 4, wherein, The first dimension W1 of the guide surface in the radial direction of the electrode lead-out hole and the first thickness T1 of the main body satisfy the relationship: 0.1≤W1 / T1≤1.

6. The battery cell according to any one of claims 1-5, wherein, The first connecting portion includes a first part and a second part, the first part surrounding the outer side of the first recess, the second part surrounding the inner side of the first recess, and the second part connecting the first part and the main body.

7. The battery cell according to claim 6, wherein, The first thickness T1 of the main body and the second thickness T2 of the second part satisfy the relationship: 0.5≤T2 / T1≤4.

8. The battery cell according to claim 6, wherein, The first connecting portion further includes a third portion, which is connected between the first portion and the second portion, and the first portion, the second portion and the third portion together define the first recess.

9. The battery cell according to claim 8, wherein, The third part has a second dimension W2 on the side surface facing away from the wall in a direction perpendicular to the thickness direction of the wall. The first thickness T1 and the second dimension W2 of the main body satisfy the relationship: 0.1≤W2 / T1≤7.

10. The battery cell according to claim 8, wherein, The third part has a third dimension W3 on one side surface facing the wall in a direction perpendicular to the thickness direction of the wall. The first thickness T1 of the main body and the third dimension W3 satisfy the relationship: 0.25≤W3 / T1≤10.

11. The battery cell according to claim 8, wherein, The first thickness T1 of the main body and the third thickness T3 of the third part satisfy the relationship: 0.4≤T3 / T1≤2.

5.

12. The battery cell according to claim 8, wherein, The first connecting portion further includes a first arc surface, which connects the side surface of the third portion facing away from the wall portion and the side surface of the first portion facing the first recess.

13. The battery cell according to claim 12, wherein, The first arc length R1 of the first arc surface satisfies the relationship: 0.25mm≤R1≤5mm.

14. The battery cell according to claim 8, wherein, The first connecting portion further includes a second arc surface, which connects the side surface of the third portion facing away from the wall portion and the side surface of the second portion facing the first recess.

15. The battery cell according to claim 14, wherein, The second arc length R2 of the second arc surface satisfies the relationship: 0.5mm≤R2≤6mm.

16. The battery cell according to any one of claims 1-15, wherein, The outer side of the wall is provided with a groove, and at least a portion of the first connecting portion is accommodated in the groove.

17. The battery cell according to any one of claims 1-16, wherein, The main body includes a fourth part and a fifth part, the fifth part being connected to the fourth part and the first connecting part, the fourth part being embedded inside the insulating member, and the fifth part being exposed outside the insulating member.

18. The battery cell according to claim 17, wherein, The end face of the portion of the first connecting part surrounding the outside of the first recess, on the side away from the wall in the thickness direction, is flush with the surface of the fifth portion on the side away from the wall in the thickness direction.

19. The battery cell according to any one of claims 1-18, wherein, The housing includes a shell and an end cap, the shell having an opening and the end cap closing the opening; The end cap is configured as the wall portion.

20. The battery cell according to claim 19, wherein, The battery cell also includes an electrode assembly, which is housed within the housing; The end cap includes a cap body, a second connecting portion and a second recess, the second connecting portion being connected to the cap body, the second recess being disposed on the side of the second connecting portion facing away from the electrode assembly, and at least a portion of the second connecting portion surrounding the outside of the second recess and being welded to the housing.

21. The battery cell according to claim 20, wherein, The second connecting portion includes a second protrusion, the position of which corresponds to the position of the second recess, and the second protrusion protrudes from the side surface of the cover body facing the electrode assembly.

22. A battery comprising a plurality of battery cells as described in any one of claims 1-21.

23. An electrical device comprising a battery cell as described in any one of claims 1-21, the battery cell being used to provide electrical energy.

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