End cover, battery monomer, battery and electric device

Abstract

The utility model provides an end cover, a battery monomer, a battery and a power utilization device, the battery monomer comprises a shell, an electrode assembly and the end cover, the end part of the shell in a first direction is provided with an opening, and the electrode assembly is accommodated in the shell. The end cover is used for covering the opening and comprises an end cover body located in the projection of the opening in the first direction, and the end cover is welded to the shell and forms a molten pool structure. In the radial direction of the opening, the molten pool structure is exposed out of the outer surface of the shell and extends into the end cover body. According to the embodiment of the invention, the laser needs to be irradiated from the peripheral side of the shell to the position near the junction position of the shell and the protruding part in the radial direction, so that the formed molten pool structure can comprise most or even all structures in the protruding part, a part of structures of the shell and a part of structures in the end cover main body; therefore, the overall size of the molten pool structure is increased, and the welding strength between the shell and the end cover is improved.

Description

Technical Field

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

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

[0003] However, during use, the electrode assembly within the battery cell will expand and transfer the corresponding expansion stress to the outer casing, thereby causing the risk of the outer casing rupture and affecting the reliability of the battery cell. Utility Model Content

[0004] In view of the above problems, the present application provides an end cover, a battery cell, a battery and an electrical device, which can improve the reliability of the battery cell.

[0005] On the one hand, an embodiment of the present application provides a battery cell, including a shell, an electrode assembly and an end cap, wherein the shell has an opening at an end in a first direction, and the electrode assembly is accommodated in the shell. The end cap is used to cover the opening, and the end cap includes an end cap body located in a projection of the opening along the first direction, and the end cap is welded to the shell to form a molten pool structure. In the radial direction of the opening, the molten pool structure is exposed on the outer surface of the shell and penetrates into the interior of the end cap body.

[0006] In the above scheme, the laser needs to be irradiated from the outer peripheral side of the shell and in the radial direction to the vicinity of the junction between the shell and the end cover. This design allows the formed molten pool structure to penetrate into the interior of the end cover body, that is, the molten pool structure can include part of the structure in the end cover body, which helps to increase the overall size of the molten pool structure and improve the welding strength between the shell and the end cover. At the same time, at least part of the relatively weak area near the molten pool structure can be located on the end cover body. Since the end cover body usually has a large thickness and strength, it helps to reduce the risk of cracks or even fractures in the relatively weak area near the molten pool structure, thereby improving the reliability and service life of the battery cell.

[0007] In some embodiments, the size of the molten pool structure tends to gradually decrease in the direction from the outer surface of the shell to the inner surface of the shell.

[0008] In the above scheme, compared with the scheme in the related art where the molten pool structure extends deep into the shell along the first direction, this design can reduce the impact of the molten pool structure on the shell, thereby reducing the exposed size of the molten pool structure at the outer surface of the shell, improving the flatness of the outer surface of the shell, and improving the appearance of the battery cell. In addition, in the direction from the outer surface of the shell to the inner surface of the shell, the size of the molten pool structure tends to gradually decrease, which helps to reduce the structural size of the molten pool structure extending deep into the center of the end cover body, thereby reducing the impact of the molten pool structure on the central position of the end cover body and improving the structural reliability of the end cover body.

[0009] In some embodiments, the shell includes a first plate portion, the first plate portion is fixed to the end cover, and the molten pool structure is arranged beyond the inner surface of the first plate portion. In the radial direction of the opening, the maximum size of the molten pool structure is H1, the size of the first plate portion is H2, and H1 and H2 satisfy: H2+0.15mm≤H1≤3mm.

[0010] In the above scheme, H1 is set to be no less than H2+0.15mm, so that the molten pool structure can penetrate into the end cover body, thereby achieving welding fusion between the end cover body and the first plate portion, and improving the reliability of the battery cell. In addition, the embodiment of the present application also sets H1 to be no more than 3mm, so as to reduce the risk of serious deformation of the shell after welding due to excessive melting depth of the molten pool structure, resulting in excessive energy input during welding, and improve the reliability of the shell structure in the battery cell.

[0011] In some embodiments, in the radial direction of the opening, the distances H3, H2 and H3 between the outer surface of the end cover body facing the first plate portion and the outer surface of the first plate portion satisfy: H3≤H2+0.5 mm.

[0012] In the above scheme, the size of the gap space formed between the end cover body and the first plate portion in the radial direction is set to be no greater than 0.5 mm, so as to reduce the risk of the liquid molten structure falling off in the gap space during the melting process, reduce the adverse effects of the welding process on the electrode assembly, and help to improve the structural reliability of the finally formed molten pool structure in the gap space, thereby improving the welding strength between the end cover and the shell.

[0013] In some embodiments, the shell includes a first plate portion, the first plate portion is fixed to the end cover, and the molten pool structure extends to the upper surface of the end cover away from the shell. In the radial direction of the opening, the size of the first plate portion is H2. In the first direction, the maximum size of the molten pool structure is L1, and the maximum size of the end cover body is L3, and L1, L3 and H2 satisfy: L1≤L3+2H2.

[0014] In the above scheme, L1 is set to be no greater than L3+2H2, so as to reduce the risk of the liquid molten structure formed during the welding process flowing to the side of the end cover body facing the electrode assembly, reduce the impact of the welding process on the electrode assembly and other parts, and improve the preparation yield of the battery cell.

[0015] In some embodiments, the shell includes a first plate portion and a second plate portion, the first plate portion is located on a side of the second plate portion close to the opening, the molten pool structure portion is located in the first plate portion, and the thickness of the first plate portion is greater than the thickness of the second plate portion.

[0016] In the above solution, the structure of the shell is adjusted so that the thickness of the first plate portion in the shell used for welding is greater than the thickness of the first plate portion, thereby improving the welding strength between the shell and the end cover and improving the reliability of the battery cell.

[0017] In some embodiments, in the first direction, the first plate portion is located on a side of the electrode assembly facing the opening.

[0018] In the above scheme, in the first direction, the first plate portion is arranged on the side of the electrode assembly facing the opening K, that is, the first plate portion and the electrode assembly are located at different heights in the first direction, thereby reducing the probability of contact between the electrode assembly and the first plate portion due to expansion of the electrode assembly, reducing the risk of stress concentration at the first plate portion, and improving the reliability of the battery cell.

[0019] In some embodiments, the inner surface of the first plate portion is arranged beyond the inner surface of the second plate portion, and in the first direction, the size of the first plate portion is L5, and L5 satisfies: L5≤10 mm.

[0020] In the above scheme, L5 is set to no more than 10 mm, thereby reducing the risk of contact interference between the electrode assembly and the first plate portion due to expansion of the electrode assembly, thereby reducing the probability of stress concentration between the electrode assembly and the first plate portion, thereby reducing the probability of lithium plating problems and improving the reliability of the battery cell.

[0021] In some embodiments, the outer surface of the first plate portion is arranged beyond the outer surface of the second plate portion, and in the first direction, the size of the first plate portion is L5, and L5 satisfies: L5≤15mm.

[0022] In the above solution, the size of the first plate in the first direction is limited so that L5 is no larger than 15 mm, thereby reducing the risk of the protruding structure of the first plate colliding with other external components and improving the reliability of the battery cell.

[0023] In some embodiments, the thickness of the first plate portion is H2, the thickness of the second plate portion is H4, and H2 and H4 satisfy: H4<H2≤1.8H4.

[0024] In the above solution, by setting the thickness H2 of the first plate portion to be greater than the thickness H4 of the second plate portion, the welding strength between the shell and the end cover can be improved, thereby improving the reliability of the battery cell. At the same time, H2 is set to be no greater than 1.8H4, thereby satisfying the molding feasibility of the first plate portion and the second plate portion and reducing the difficulty of preparing the shell.

[0025] In some embodiments, the structure of the molten pool structure located within the shell does not extend beyond the first plate portion.

[0026] In the above solution, the structure in the molten pool structure located inside the shell does not exceed the first plate portion, that is, the molten pool structure does not extend into the second plate portion. In this case, when the electrode assembly expands, cracks are more likely to occur in the first plate portion, and the cracks generated need to penetrate the first plate portion in the radial direction to cause the shell to rupture. Therefore, this design helps to increase the crack path length corresponding to the cracks generated near the molten pool structure due to the expansion of the electrode assembly, thereby improving the reliability of the battery cell.

[0027] In some embodiments, the shell includes a first side plate, a second side plate and a connecting plate connecting the first side plate and the second side plate, and the connecting plate includes an arc structure. The first side plate includes a first plate portion and a second plate portion, and the first plate portion is located on a side of the second plate portion close to the opening. The second side plate includes a third plate portion and a fourth plate portion, and the third plate portion is located on a side of the fourth plate portion close to the opening. The connecting plate includes a fifth plate portion and a sixth plate portion, and the fifth plate portion is located on a side of the sixth plate portion close to the opening. The thickness of the first plate portion is greater than the thickness of the second plate portion; and / or the thickness of the third plate portion is greater than the thickness of the fourth plate portion; and / or the thickness of the fifth plate portion is greater than the thickness of the sixth plate portion.

[0028] In the above scheme, according to the different locations of the weak areas on the shell, at least one of the first plate portion, the third plate portion and the fifth plate portion can be selectively thickened to achieve the reinforcement of the shell strength. At the same time, compared with the scheme of thickening the entire shell, the embodiment of the present application is only partially thickened, which helps to reduce material waste and space occupied by the electrode assembly.

[0029] In some embodiments, the thickness of the first plate portion is greater than the thickness of the second plate portion; and / or, the thickness of the third plate portion is greater than the thickness of the fourth plate portion; and / or, the thickness of the fifth plate portion is greater than the thickness of the sixth plate portion.

[0030] In the above solution, the thickness difference between the first plate portion and the second plate portion is the thickness increase of the first plate portion relative to the second plate portion. On this basis, by setting the thickness increase of the first plate portion equal to the thickness increase of the third plate portion, the difficulty of manufacturing the first plate portion and the third plate portion can be reduced. Alternatively, the thickness increase of the first plate portion can be set equal to the thickness increase of the fifth plate portion, which helps to reduce the difficulty of manufacturing the first plate portion and the fifth plate portion.

[0031] In some embodiments, the shell includes a first plate portion, the first plate portion is fixed to the end cover, and the thickness of the end cover body is greater than the thickness of the first plate portion.

[0032] In the embodiment of the present application, since the thickness of the end cap body is greater than the thickness of the first plate portion, the end cap body can have greater structural strength than the first plate portion. On this basis, the embodiment of the present application changes the welding method and the morphology of the molten pool structure, so that at least part of the relatively weak area near the molten pool structure can be located on the end cap body, which helps to reduce the risk of cracks or even fractures in the relatively weak area near the molten pool structure, and improves the reliability and service life of the battery cell.

[0033] In a second aspect, an embodiment of the present application provides an end cover of a battery cell, comprising an end cover body and a protrusion, wherein the protrusion is arranged to protrude from the outer peripheral surface of the end cover body, and both the protrusion and the end cover body are used for welding with the shell of the battery cell to form a molten pool structure.

[0034] In a third aspect, an embodiment of the present application provides a battery, comprising a battery cell in any of the aforementioned embodiments.

[0035] In some embodiments, the battery further includes a heat insulating pad disposed between adjacent battery cells, the housing includes a first plate portion and a second plate portion, the first plate portion is located on a side of the second plate portion close to the opening, and the outer peripheral surface of the first plate portion protrudes from the outer peripheral surface of the second plate portion. The projection of at least part of the structure of the heat insulating pad in the first direction X is located between the projections of two adjacent first plate portions in adjacent battery cells in the first direction.

[0036] In the above scheme, a thermal insulation pad is arranged between adjacent battery cells, and the projection of at least part of the structure in the thermal insulation pad in the first direction can be located between the projections of the first plate portions in different battery cells in the first direction, so that the first plate portions corresponding to different battery cells can be separated by means of the thermal insulation pad, thereby reducing the risk of collision and damage between the first plate portions corresponding to different battery cells.

[0037] In some embodiments, in the first direction, at least a portion of the structure in the first plate portion is located on one side of the thermal insulation pad. And / or, a recess is provided on the thermal insulation pad, and at least a portion of the first plate portion is embedded in the recess.

[0038] In the above solution, the spacing between different first plates can be achieved by means of thermal insulation pads, thereby reducing the risk of stress concentration between different first plates. In a fourth aspect, an embodiment of the present application provides an electrical device, including a battery cell in any of the above embodiments, the battery cell is used to provide electrical energy.

[0039] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 is a structural schematic diagram of a vehicle provided in an embodiment of the present application;

[0042] Figure 2 is a schematic diagram of an exploded structure of a battery provided in an embodiment of the present application;

[0043] Figure 3 is a structural schematic diagram of a battery module provided in an embodiment of the present application;

[0044] Figure 4 is a schematic diagram of the structure of a battery cell provided in an embodiment of the present application;

[0045] Figure 5 is a schematic diagram of a cross-sectional structure of a battery cell provided in an embodiment of the present application;

[0046] Figure 6 yes Figure 5 Schematic diagram of the cross-sectional structure of the middle region Q;

[0047] Figure 7 is a schematic diagram of a partial cross-sectional structure of another battery cell provided in an embodiment of the present application;

[0048] Figure 8 is a schematic diagram of a partial cross-sectional structure of another battery cell provided in an embodiment of the present application;

[0049] Fig. 9 is a schematic diagram of assembling adjacent battery cells in a battery module provided by an embodiment of the present application;

[0050] Fig.10 is a schematic diagram of a partial cross-sectional structure of a battery module provided in an embodiment of the present application;

[0051] Fig.11 yes Fig.10 Schematic diagram of the enlarged structure of the middle area P;

[0052] Fig.12 It is a schematic diagram of the structure of a shell in a battery cell provided in an embodiment of the present application;

[0053] Fig.13 yes Fig.12 Schematic diagram of the enlarged structure of the middle area O;

[0054] Fig.14 It is a structural schematic diagram of an end cover provided in an embodiment of the present application;

[0055] Fig.15 This is a schematic diagram of a local structure in another battery provided in an embodiment of the present application.

[0056] In the attached figure:

[0057] 1000. Vehicles;

[0058] 100, battery; 200, controller; 300, motor; 400, housing; 41, first housing portion; 42, second housing portion; 43, storage portion; 500, battery module; 600, battery cell

[0059] 10. Shell; 11. Shell; 111. First plate portion; 112. Second plate portion; 113. Third plate portion; 114. Fourth plate portion; 115. Fifth plate portion; 116. Sixth plate portion; 12. End cover; 121. End cover body; 122. Protrusion;

[0060] 20. Electrode assembly;

[0061] 30. Insulation pad;

[0062] K, opening; R, molten pool structure; R1, first molten pool part;

[0063] A. concave part;

[0064] B1, first side plate; B2, second side plate; B3, connecting plate;

[0065] X, first direction; Y, radial direction. DETAILED DESCRIPTION

[0066] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0068] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0069] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0070] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0071] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0072] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0073] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0074] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0075] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0076] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0077] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0078] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0079] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc., treated with silver surface, may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0080] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0081] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0082] As an example, the negative electrode current collector can be a metal foil, a foamed metal or a composite current collector. For example, as a metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. can be used. The foamed metal can be a foamed nickel, a foamed copper, a foamed aluminum, a foamed alloy, or a foamed carbon, etc. The composite current collector can include a polymer material base and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0083] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0084] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0085] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.

[0086] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0087] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0088] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical stability and mechanical stability can be selected.

[0089] As an example, the main material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics.

[0090] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0091] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. The electrolyte can be liquid, gel or solid.

[0092] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0093] In some embodiments, the electrode assembly is a laminate structure.

[0094] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0095] In some embodiments, the electrode assembly is provided with tabs, which can lead current out of the electrode assembly. The tabs include a positive tab and a negative tab.

[0096] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0097] In some embodiments, the housing may be provided with functional components such as electrode terminals, etc. The electrode terminals may be used to electrically connect to the electrode assembly to output or input electrical energy of the battery cell.

[0098] In some embodiments, a current collecting member may be disposed in the housing, and the electrode assembly may be electrically connected to the housing or an electrode terminal disposed on the housing through the current collecting member.

[0099] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc. There is no special limitation in this application.

[0100] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0101] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0102] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are accommodated in the case.

[0103] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0104] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0105] During the preparation of battery cells, the end caps and shells of the battery cells are usually connected and fixed by welding to form an outer shell. During the use of the battery cells, the electrode assembly will expand, and the welding area will be subject to a certain expansion stress, which will easily lead to the risk of cracking of the outer shell at the corresponding welding area, thereby causing the battery cells to fail and affecting the reliability of the battery cells.

[0106] Based on the above technical problems, the present application provides an end cover, a battery cell, a battery and an electrical device. By changing the welding method, the welding strength between the end cover and the shell is improved, the risk of cracking of the battery cell is reduced, and the service life and reliability of the battery cell are improved.

[0107] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries, such as mobile phones, portable devices, laptop computers, electric vehicles, electric cars, ships, spacecraft, electric toys and electric tools, etc., wherein spacecrafts include airplanes, rockets, space shuttles and spacecrafts, etc., electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc., and electric 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.

[0108] The battery cells described in the embodiments of the present application are not limited to being applicable to the electrical devices described above, but for the sake of simplicity, the following embodiments are described using electric vehicles as examples.

[0109] See also Figure 1 , Figure 1 A simple schematic diagram of a vehicle 1000 provided in an embodiment of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 may be provided inside the vehicle 1000, and specifically, for example, the battery 100 may be provided at the bottom, front or rear of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used, for example, to control the battery to power the motor 300. The battery may be used for starting and navigating the vehicle 1000, and of course, the battery 100 may also be used to drive the vehicle 1000, replacing or partially replacing fuel or natural gas to provide drive for the vehicle 1000.

[0110] Figure 2 Schematic diagram of an explosion of a battery provided in some embodiments of the present application. Figure 2 As shown, the battery 100 includes a housing 400 and a battery cell (not shown in the figure), and the battery cell is accommodated in the housing 400 .

[0111] The box 400 is used to accommodate the battery cells, and the box 400 can be a variety of structures. In some embodiments, the box 400 may include a first box portion 41 and a second box portion 42, the first box portion 41 and the second box portion 42 cover each other, and the first box portion 41 and the second box portion 42 jointly define a receiving portion 43 for accommodating the battery cells. The second box portion 42 may be a hollow structure with one end open, the first box portion 41 is a plate-like structure, and the first box portion 41 covers the open side of the second box portion 42 to form a box with a receiving portion 43; the first box portion 41 and the second box portion 42 may also be a hollow structure with one side open, and the open side of the first box portion 41 covers the open side of the second box portion 42 to form a box 400 with a receiving portion 43. Of course, the first box portion 41 and the second box portion 42 may be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0112] In the battery 100, there can be one or more battery cells. If there are multiple battery cells, the multiple battery cells can be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple battery cells are connected in series and in parallel. Multiple battery cells can be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells is accommodated in the box 400; of course, multiple battery cells can also be connected in series, in parallel, or in mixed connection to form a battery module 500, and multiple battery modules 500 are then connected in series, in parallel, or in mixed connection to form a whole, and accommodated in the box 400.

[0113] Figure 3 for Figure 2 A schematic structural diagram of a battery module 500 is shown.

[0114] In some embodiments, Figure 3 As shown, there are multiple battery cells 600, and the multiple battery cells 600 are first connected in series, parallel or mixed to form a battery module 500. The multiple battery modules 500 are then connected in series, parallel or mixed to form a whole, and are accommodated in a box.

[0115] Figure 4 It is a schematic diagram of the structure of a battery cell. Figure 5 The internal structure of the battery cell is shown in FIG.

[0116] See also Figures 4 to 6 The battery cell 600 includes a shell 11, an electrode assembly 20 and an end cap 12. The shell 11 has an opening K at the end in the first direction X, and the electrode assembly 20 is accommodated in the shell 11. The end cap 12 is used to cover the opening K. The end cap 12 includes an end cap body 121. The projection of the end cap body 121 along the first direction X is located within the projection of the opening K along the first direction X. The end cap 12 is welded to the shell 11 and forms a molten pool structure R. In the radial direction Y of the opening K, the molten pool structure R is exposed on the outer surface of the shell 11 and penetrates into the interior of the end cap body 121.

[0117] The shell 11 and the end cap 12 are welded and fixed to form a housing 10 together. The housing 10 is a hollow structure for forming a storage space for placing the electrode assembly 20 and other parts. The end cap 12 includes an end cap body 121. Further, the "end cap 12 includes an end cap body 121 located in the projection of the opening K along the first direction X" mentioned in the embodiment of the present application means that along the first direction X, the projection of the end cap body 121 is located in the projection of the opening K. Among them, the first direction X can be the thickness direction of the end cap body 121.

[0118] The electrode assembly 20 is a main component in the battery cell 600 for providing electric energy, and the shapes of the housing 11 and the end cap 12 can be determined according to the shape of the electrode assembly 20. For example, if the electrode assembly 20 is a cylindrical structure, the housing 11 has a cylindrical structure, and the projection of the end cap body 121 in the first direction X is a circular or circular-like structure. If the electrode assembly 20 is a rectangular parallelepiped structure, the housing 11 has a rectangular parallelepiped structure, and the projection of the end cap body 121 in the first direction X is a rectangular or rectangular-like structure.

[0119] The end cap 12 is welded to the shell 11 to form a molten pool structure R, wherein a portion of the structure in the end cap 12 and a portion of the structure in the shell 11 can be melted into one piece during the welding process to form the molten pool structure R. For details, please refer to Figure 6 , Figure 6 , the structure of the end cover 12 before welding and the relative relationship between the end cover 12 and the molten pool structure R are shown. For example, the end cover 12 may include a protrusion 122 in addition to the end cover body 121. The protrusion 122 is arranged to protrude from the outer peripheral surface of the end cover body 121. At least part of the structure of the protrusion 122 and part of the structure of the end cover body 121 are used to be melted into one with part of the structure in the shell 11, so as to form the molten pool structure R.

[0120] The embodiment of the present application does not limit the shape and size relationship between the protrusion 122 and the end cover body 121. For example, the cross-sectional shape of the protrusion 122 and the end cover body 121 can be T-shaped, and when the end cover body 121 is projected as a circle in its own thickness direction, the projection of the protrusion 122 in the thickness direction of the end cover body 121 can be a circular ring structure. When the end cover body 121 is projected as a square in its own thickness direction, the projection of the protrusion 122 in the thickness direction of the end cover body 121 can be a square ring structure.

[0121] In the related art, the welding between the shell 11 and the end cover 12 can be achieved with the help of laser, and the laser is usually irradiated on the protrusion 122 along the first direction X from the side of the end cover 12 away from the electrode assembly 20, so that part of the structure in the protrusion 122 is melted with the shell 11 to form a molten pool structure R, and the welding and fixing between the end cover 12 and the shell 11 is achieved. However, this welding method can usually only weld and fix the protrusion 122 to the shell 11, and the end cover body 121 will not be directly melted and fixed with the shell 11. In this way, during the use of the battery cell 600, due to the expansion of the electrode assembly 20, the area with low strength around the molten pool structure R, that is, the junction between the protrusion 122 and the end cover body 121, is more susceptible to the expansion stress. On this basis, due to the small size of the protrusion 122 itself, the structural strength at the protrusion 122 will be further reduced, thereby accelerating the risk of cracks or even cracking at the position of the protrusion 122, affecting the reliability and service life of the battery cell 600.

[0122] In view of this, the embodiment of the present application adjusts the method of laser irradiation during the welding process, thereby changing the shape and size of the molten pool structure R, which helps to reduce the risk of cracking of the battery cell 600. Specifically, in the radial direction Y of the opening K, the molten pool structure R is exposed on the outer surface of the shell 11 and penetrates into the interior of the end cover body 121. The "radial direction Y" mentioned here refers to: any direction passing through the center of the opening K and perpendicular to the first direction X. Exemplarily, when the projection shape of the opening K in the first direction X is a circle, the radial direction Y can be the radial direction of the circle. When the projection shape of the opening K in the first direction X is a rectangular or trapezoidal structure, the radial direction Y can be the radial direction of the circumscribed circle of the trapezoid or rectangle.

[0123] In addition, the "molten pool structure R exposed on the outer surface of the shell 11" mentioned in the embodiment of the present application means that the outer surface of the molten pool structure R can be observed on the outer peripheral side of the shell 11 and along the radial direction Y. The outer surface of the molten pool structure R can protrude from the outer surface of the shell 11, or can be concave or flush with the outer surface of the shell 11, as long as the molten pool structure R can be observed on the outer peripheral side of the shell 11 and along the radial direction Y.

[0124] Furthermore, the molten pool structure R can also penetrate into the interior of the end cover body 121, that is, the molten pool structure R can directly weld and fix the shell 11 and the end cover body 121. In order to meet the size and shape requirements of the molten pool structure R, during the welding process of the end cover 12 and the shell 11, it is necessary to irradiate the laser from the outer peripheral side of the shell 11 and along the radial direction Y to the vicinity of the junction between the shell 11 and the end cover 12, wherein Figure 6 The direction of the arrow in the figure indicates the irradiation direction of the laser. This design allows the formed molten pool structure R to penetrate into the interior of the end cover body 121, that is, the molten pool structure R may include a portion of the structure in the end cover body 121, thereby helping to increase the overall size of the molten pool structure R and improve the welding strength between the shell 11 and the end cover 12. At the same time, at least part of the relatively fragile area near the molten pool structure R can be located on the end cover body 121. Since the end cover body 121 usually has a large thickness and strength, it helps to reduce the risk of cracks or even fractures in the relatively fragile area near the molten pool structure R, thereby improving the reliability and service life of the battery cell 600.

[0125] In some embodiments, Figure 6 As shown, in the direction from the outer surface of the shell 11 to the inner surface of the shell 11, the size of the molten pool structure R tends to gradually decrease.

[0126] In combination with the foregoing, it can be seen that in order to improve the welding strength between the shell 11 and the end cover 12 of the battery cell 600 and reduce the risk of cracking of the outer shell 10 due to the expansion of the electrode assembly 20, the embodiment of the present application changes the welding method between the end cover 12 and the shell 11, so that the laser is irradiated from the outer peripheral side of the shell 11 and along the radial direction Y to the vicinity of the junction between the shell 11 and the end cover 12, so that the formed molten pool structure R can penetrate into the interior of the end cover body 121.

[0127] Furthermore, the molten pool structure R finally formed in the embodiment of the present application is usually different from the molten pool structure R in the related art. Specifically, the molten pool structure R in the embodiment of the present application will penetrate into the interior of the end cover body 121 along the radial direction Y. Therefore, in the direction from the outer surface of the shell 11 to the inner surface of the shell 11, the size of the molten pool structure R tends to gradually decrease.

[0128] Compared with the solution in the related art that the molten pool structure R extends deep into the shell 11 along the first direction X, this design can reduce the impact of the molten pool structure R on the shell 11, thereby reducing the exposed size of the molten pool structure R at the outer surface of the shell 11, improving the flatness of the outer surface of the shell 11, and improving the appearance of the battery cell 600. In addition, in the direction from the outer surface of the shell 11 to the inner surface of the shell 11, the size of the molten pool structure R tends to gradually decrease, which helps to reduce the structural size of the molten pool structure R extending to the deep center of the end cover body 121, thereby reducing the impact of the molten pool structure R on the central position of the end cover body 121 and improving the structural reliability of the end cover body 121.

[0129] In some embodiments, Figure 6 As shown, the shell 11 includes a first plate portion 111, the first plate portion 111 is fixed to the end cover 12, and the molten pool structure R is arranged beyond the inner surface of the first plate portion 111. In the radial direction Y of the opening K, the maximum size of the molten pool structure R is H1, and the size of the first plate portion 111 is H2, and H1 and H2 satisfy: H2+0.15mm≤H1≤3mm.

[0130] The first plate portion 111 is located at the end of the shell 11. The first plate portion 111 can be used to enclose the opening K, wherein at least part of the structure of the first plate portion 111 can be used to be welded and fixed to the end cover 12. In the radial direction Y of the opening K, the size of the first plate portion 111 is H2, that is, the thickness of the first plate portion 111 is H2. It should be noted that, according to the actual needs of different battery cells 600, the thickness of the shell 11 can be kept consistent at various locations, or the thickness of the shell 11 at different locations can also be different.

[0131] The size and shape of the first plate portion 111 can have various forms. For example, before the end cover 12 is welded to the shell 11, the outer surface of the protrusion 122 in the end cover 12 in the radial direction Y can be set beyond the outer surface of the first plate portion 111, or the outer surface of the protrusion 122 in the radial direction Y can also be concave or flush with the outer surface of the first plate portion 111.

[0132] In the radial direction Y of the opening K, the maximum dimension of the molten pool structure R is H1, that is, H1 is the maximum melting depth of the molten pool structure R. In combination with the above content, it can be seen that the molten pool structure R needs to penetrate into the interior of the end cover body 121, so the maximum dimension H1 corresponding to the molten pool structure R needs to be greater than the thickness dimension H2 of the first plate portion 111. Furthermore, the embodiment of the present application also sets H1 to be not less than H2+0.15mm, so that the molten pool structure R can penetrate into the interior of the end cover body 121, thereby achieving welding and melting between the end cover body 121 and the first plate portion 111, and improving the reliability of the battery cell 600.

[0133] In addition, the embodiment of the present application also sets H1 to no more than 3 mm, thereby reducing the risk of excessive energy input during welding due to excessive penetration of the molten pool structure R, which may cause serious deformation of the shell 11 after welding, thereby improving the reliability of the shell 11 structure in the battery cell 600.

[0134] In some embodiments, in the radial direction Y of the opening K, the dimension of the molten pool structure R extending from the outer surface of the end cover body 121 to the outer surface of the first plate portion 111 is H3, and H2 and H3 satisfy: H3≤H2+0.5mm. Optionally, the value of H3-H2 is one of 0.1mm, 0.2mm, 0.25mm, 0.4mm and 0.5mm.

[0135] After the shell 11 and the end cover 12 are welded and fixed, the effective penetration depth dimension in the molten pool structure R for achieving the welding fixing effect corresponds to H3. In the manufacturing process of the shell 11 and the end cover 12, in order to meet the assembly requirements between the shell 11 and the end cover 12, it is usually necessary to set the projection dimension of the end cover body 121 in the first direction X to be smaller than the projection dimension of the opening K in the first direction X, so that the end cover body 121 can be inserted into the opening K. Under this design, in the radial direction Y of the opening K, there will be a gap space between the outer surface of the end cover body 121 and the inner surface of the first plate portion 111, that is, the effective penetration depth H3 will be greater than the thickness H2 of the first plate portion 111. Further, the numerical value of H3-H2 is the size of the gap space between the end cover body 121 and the first plate portion 111 in the radial direction Y, and the size of H3-H2 will usually also affect the preparation of the formed molten pool structure R.

[0136] Specifically, during the welding process of the end cap 12 and the shell 11, part of the structure in the shell 11 will melt into a liquid structure, and part of the structure in the end cap 12 will also melt into a liquid structure. The liquid structure corresponding to the shell 11 and the liquid structure corresponding to the end cap 12 will blend with each other and solidify to form a molten pool structure R. In this process, if the dimension H3-H2 of the gap space in the radial direction Y is too large, the liquid structure formed by the melting of the shell 11 and the liquid structure formed by the melting of the end cap 12 may fall from the gap space, which may easily damage the structure of the electrode assembly 20, which is not conducive to the yield rate of the battery cell 600. At the same time, the molten pool structure R may produce structural defects in the gap space, affecting the welding reliability between the end cap 12 and the shell 11, thereby easily having an adverse effect on the use of the battery cell 600.

[0137] In view of this, the embodiment of the present application sets H3≤H2+0.5mm, that is, the size of the gap space formed between the end cover body 121 and the first plate portion 111 in the radial direction Y is set to be no more than 0.5mm, so as to reduce the risk of the liquid molten structure falling off in the gap space during the melting process, reduce the adverse effects of the welding process on the electrode assembly 20, and at the same time help to improve the structural reliability of the finally formed molten pool structure R in the gap space, thereby improving the welding strength between the end cover 12 and the shell 11.

[0138] In some embodiments, Figure 6 As shown, the molten pool structure R extends to the upper surface of the end cover 12 away from the shell 11. In the radial direction Y of the opening K, the size of the first plate portion 111 is H2. In the first direction X, the maximum size of the molten pool structure R is L1, and the maximum size of the end cover body 121 is L3. L1, L3 and H2 satisfy: L1≤L3+2H2.

[0139] The maximum dimension L1 of the molten pool structure R in the first direction X is the maximum molten width of the molten pool structure R. Generally, the maximum dimension L1 of the molten pool structure R in the first direction X is positively correlated with the maximum dimension H1 of the molten pool structure R in the radial direction Y, that is, the larger the maximum dimension H1 of the molten pool structure R in the radial direction Y, the larger the maximum dimension L1 of the molten pool structure R in the first direction X will be.

[0140] Further, the molten pool structure R extends to the upper surface of the end cover 12 away from the shell 11, that is, during the welding process, the molten pool structure R can reach the upper surface of the protrusion 122, and the molten pool structure R can extend from the protrusion 122 to the first plate portion 111 in the first direction X, so that at least part of the structure in the first plate portion 111 and at least part of the structure in the protrusion 122 can be melted into one, thereby improving the welding strength between the end cover 12 and the shell 11. In some optional embodiments, in the first direction X, the size of the protrusion is L2, L2+0.1mm≤L1.

[0141] If the maximum dimension L1 of the molten pool structure R in the first direction X is too large, it is easy to cause the liquid molten structure formed during the welding process to partially flow to the side of the end cover body 121 facing the electrode assembly 20, which is easy to have an adverse effect on the electrode assembly 20 and there will be certain welding defects. In view of this, the embodiment of the present application also sets L1 to be no larger than the dimension L3+2H2 of the end cover body 121 in the first direction X, where the dimension L3 of the end cover body 121 in the first direction X can also be the dimension of the entire end cover 12 in the first direction X. This design can reduce the risk of the liquid molten structure formed during the welding process flowing to the side of the end cover body 121 facing the electrode assembly 20, reduce the impact of the welding process on the electrode assembly 20 and other parts, and improve the preparation yield of the battery cell 600.

[0142] In summary, the embodiment of the present application sets L1 to no greater than L3+2H2, thereby reducing the risk of the liquid molten structure formed during the welding process flowing to the side of the end cover body 121 toward the electrode assembly 20, reducing the impact of the welding process on parts such as the electrode assembly 20, and improving the preparation yield of the battery cell 600.

[0143] In some embodiments, Figure 6 As shown, the molten pool structure R includes a first molten pool portion R1 located in the end cover 12, and the size of the first molten pool portion R1 in the first direction X is L4, and L4 and L2 satisfy: L2+0.05mm≤L4≤L2+0.5mm. Optionally, L4 is one of L2+0.05mm, L2+0.1mm, L2+0.2mm, L2+0.3mm and L2+0.5mm.

[0144] The first molten pool portion R1 is a partial structure of the molten pool structure R located in the end cover 12, wherein the first molten pool portion R1 may be partially located in the protrusion 122 and partially located in the end cover body 121. Further, the dimension L4 of the first molten pool portion R1 in the first direction X is the effective molten width of the molten pool structure R that can achieve the welding effect. On this basis, if the dimension L4 of the first molten pool portion R1 in the first direction X is less than or equal to the dimension L2 of the protrusion 122 in the first direction X, then during the welding process, the laser may only irradiate the protrusion 122 on the outer peripheral side of the shell 11, but not on the shell 11, which may cause the shell 11 to be unable to be welded and fixed to the end cover 12, or the welding strength between the end cover 12 and the shell 11 is too low.

[0145] In view of this, the embodiment of the present application sets L4 to be no less than L2+0.05mm, so as to ensure that the laser can be irradiated on the shell 11 within the tolerance of the top cover process, thereby achieving simultaneous melting welding of the shell 11 and the end cover 12, and improving the welding strength between the two. In addition, the embodiment of the present application also sets L4 to be no greater than L2+0.5mm, reducing the risk of serious deformation of the shell 11 after welding due to excessive energy input during welding caused by the oversized size of the first molten pool R1, thereby improving the reliability of the shell 11 structure in the battery cell 600.

[0146] In some embodiments, see Figure 7 The shell 11 includes a first plate portion 111 and a second plate portion 112 . The first plate portion 111 is located on a side of the second plate portion 112 close to the opening K. The molten pool structure R is partially located in the first plate portion 111 . The thickness of the first plate portion 111 is greater than that of the second plate portion 112 .

[0147] The first plate portion 111 and the second plate portion 112 are arranged side by side in the first direction X, and the thickness of the first plate portion 111 and the second plate portion 112 are different, that is, the size of the first plate portion 111 and the second plate portion 112 in the radial direction Y of the opening K is different. Among them, the inner surface of the first plate portion 111 facing the electrode assembly 20 can be arranged to protrude outward relative to the inner surface of the second plate portion 112 facing the electrode assembly 20, so that the thickness of the first plate portion 111 is greater than the thickness of the second plate portion 112; and / or, the outer surface of the first plate portion 111 away from the electrode assembly 20 can be arranged to protrude outward relative to the outer surface of the second plate portion 112 away from the electrode assembly 20, so that the thickness of the first plate portion 111 is greater than the thickness of the second plate portion 112.

[0148] Furthermore, the first plate portion 111 and the second plate portion 112 can be arranged in abutment with each other in the first direction X, or the first plate portion 111 and the second plate portion 112 can be arranged at intervals in the first direction X, and there is a transition portion between the two to achieve transition and fixation of the first plate portion 111 and the second plate portion 112.

[0149] In the embodiment of the present application, the structure of the shell 11 is adjusted so that the thickness of the first plate portion 111 in the shell 11 used for welding is greater than the thickness of the first plate portion 111, thereby improving the welding strength between the shell 11 and the end cover 12 and improving the reliability of the battery cell 600.

[0150] It should be noted that, depending on the shape of the battery cell 600, the shell 11 may include multiple different side panels in the axial direction, wherein at least some of the side panels may include a first plate portion 111 and a second plate portion 112 of different thicknesses, while the thickness of other side panels at different positions may remain consistent, or there may be certain differences.

[0151] In some embodiments, in the first direction X, the first plate portion 111 is located on a side of the electrode assembly 20 facing the opening K.

[0152] It can be seen from the foregoing that the thickness of the first plate portion 111 is greater than the thickness of the second plate portion 112. On this basis, if the electrode assembly 20 and at least the structure in the first plate portion 11 are located at the same height in the first direction X, then during the use of the battery cell 600, the electrode assembly 20 may be larger in size due to expansion. At this time, if the inner surface of the first plate portion 111 exceeds the inner surface setting of the second plate portion 112, the expanded electrode assembly 20 will easily come into contact with the inner surface of the first plate portion 111, and stress concentration will easily occur between the electrode assembly 20 and the first plate portion 111, which will easily cause lithium plating problems and affect the normal use of the battery cell 600.

[0153] In view of this, in the embodiment of the present application, the first plate portion 111 is arranged on the side of the electrode assembly 20 facing the opening K in the first direction X, so that the first plate portion 111 and the electrode assembly 20 are located at different heights in the first direction X, thereby reducing the probability of contact between the electrode assembly 20 and the first plate portion 111 due to expansion of the electrode assembly 20, reducing the risk of stress concentration at the first plate portion 111, and improving the reliability of the battery cell 600.

[0154] In some embodiments, see Figure 8 The inner surface of the first plate portion 111 is arranged beyond the inner surface of the second plate portion 112 . In the first direction X, the size of the first plate portion 111 is L5 , and L5 satisfies: L5 ≤ 10 mm.

[0155] In order to make the thickness of the first plate portion 111 greater than the thickness of the second plate portion 112 , the embodiment of the present application sets the inner surface of the first plate portion 111 beyond the inner surface of the second plate portion 112 , which helps to improve the welding strength between the shell 11 and the end cover 12 and improve the reliability of the battery cell 600 .

[0156] During the use of the battery cell 600, the electrode assembly 20 will expand. On this basis, if the dimension L5 of the first plate portion 111 in the first direction X is large, at least part of the structure in the first plate portion 111 will be located at the same height as the electrode assembly 200 in the first direction X. As a result, during the expansion of the electrode assembly 20, contact interference may occur between the electrode assembly 20 and the first plate portion 111, and stress concentration may occur between the electrode assembly 20 and the first plate portion 111, which may cause lithium plating problems and affect the normal use of the battery cell 600.

[0157] In view of this, the embodiment of the present application sets L5 to no more than 10 mm, thereby reducing the risk of contact interference between the electrode assembly 20 and the first plate portion 111 due to expansion of the electrode assembly 20, thereby reducing the probability of stress concentration between the electrode assembly 20 and the first plate portion 111, and further reducing the probability of lithium plating problems, thereby improving the reliability of the battery cell 600.

[0158] It should be noted that in the embodiment of the present application, the outer surface of the first plate portion 111 can be set beyond the outer surface of the second plate portion 112, or the outer surface of the first plate portion 111 can be flush with or concave relative to the outer surface of the second plate portion 112.

[0159] In some embodiments, Figure 7 As shown, the outer surface of the first plate portion 111 is arranged beyond the outer surface of the second plate portion 112 . In the first direction X, the size of the first plate portion 111 is L5 , and L5 satisfies: L5≤15 mm.

[0160] From the foregoing, it can be seen that in addition to adjusting the inner surface of the first plate portion 111 to extend beyond the inner surface of the second plate portion 112 so that the thickness of the first plate portion 111 is greater than that of the second plate portion 112, the outer surface of the first plate portion 111 can also be set to extend beyond the outer surface of the second plate portion 112 so that the thickness of the first plate portion 111 is greater than that of the second plate portion 112.

[0161] On this basis, if the dimension L5 of the first plate portion 111 in the first direction X is too large, then during the assembly process of the battery cell 600, the part of the structure of the first plate portion 111 in the battery cell 600 that protrudes outward is prone to collision and wear with other battery cells 600 or other components, resulting in local stress concentration, thereby causing premature cracking at the welding position of the first plate portion 111, affecting the service life of the battery cell 600.

[0162] Therefore, in the embodiment of the present application, the dimension L5 of the first plate portion 111 in the first direction X is limited so that L5 is not greater than 15 mm, thereby reducing the risk of the protruding portion of the first plate portion 111 colliding with other external components and improving the reliability of the battery cell 600.

[0163] It should be noted that in the battery module 500, the number of battery cells 600 may be one or more. Figure 6 , Figures 9 to 11 If there are multiple battery cells 600, the multiple battery cells 600 are arranged side by side, and in order to reduce the mutual influence between different battery cells 600, a thermal insulation pad 30 is also arranged between adjacent battery cells 600. The thermal insulation pad 30 can reduce the heat transfer between different battery cells 600, and the thermal insulation pad 30 can also physically separate different battery cells 600. Further optionally, in the first direction X, the first plate portion 111 is located on one side of the thermal insulation pad 30, that is, the first plate portion 111 and the thermal insulation pad 30 are not located at the same height in the first direction X, so as to achieve the avoidance effect of the first plate portion 111 on the thermal insulation pad 30 and reduce the risk of stress concentration between the two.

[0164] In some embodiments, Figure 7 As shown, the thickness of the first plate portion 111 is H2, the thickness of the second plate portion 112 is H4, and H2 and H4 satisfy: H4<H2≤1.8H4. Optionally, H2 is one of 1.1H4, 1.2H4, 1.5H4, 1.6H4 and 1.8H4.

[0165] The thickness H2 of the first plate portion 111 is the dimension of the first plate portion 111 in the radial direction Y, and the thickness H4 of the second plate portion 112 is the dimension of the second plate portion 112 in the radial direction Y. In the embodiment of the present application, by setting the thickness H2 of the first plate portion 111 to be greater than the thickness H4 of the second plate portion 112, the welding strength between the housing 11 and the end cover 12 can be improved, thereby improving the reliability of the battery cell 600. At the same time, H2 is set to be no greater than 1.8H4, so that the molding feasibility of the first plate portion 111 and the second plate portion 112 can be met, and the difficulty of preparing the housing 11 can be reduced.

[0166] In some embodiments, Figure 7 As shown, the structure of the molten pool structure R located inside the shell 11 does not extend beyond the first plate portion 111 .

[0167] Generally, the strength of the housing 10 near the molten pool structure R is relatively low. On this basis, if the molten pool structure R extends into the second plate portion 112, cracks are likely to occur at the second plate portion 112 when the electrode assembly 20 expands. Furthermore, since the thickness of the second plate portion 112 is relatively thinner than that of the first plate portion 111, the cracks are likely to completely penetrate the second plate portion 112 along the radial direction Y, thereby completely rupturing the housing 11 and affecting the reliability of the battery cell 600.

[0168] In view of this, the embodiment of the present application sets the structure of the molten pool structure R located inside the shell 11 not beyond the first plate portion 111, that is, the molten pool structure R does not extend into the second plate portion 112. In this case, when the electrode assembly 20 expands, cracks are more likely to be generated in the first plate portion 111, and the generated cracks need to penetrate the first plate portion 111 along the radial direction Y to cause the shell 11 to rupture. Therefore, this design helps to increase the crack path length corresponding to the cracks generated near the molten pool structure R due to the expansion of the electrode assembly 20, and improve the reliability of the battery cell 600.

[0169] Similarly, the second edge E2 is partially located inside the end cover body 121 , and the end cover body 121 may have a larger size than the protrusion 122 , so the crack path length corresponding to the second edge E2 may also be increased, thereby improving the reliability of the battery cell 600 .

[0170] In some embodiments, see Fig.12 and Fig.13 The housing 11 includes a first side plate B1, a second side plate B2 and a connecting plate B3 connecting the first side plate B1 and the second side plate B2, and the connecting plate B3 includes an arc structure. The first side plate B1 includes a first plate portion 111 and a second plate portion 112, and the first plate portion 111 is located on the side of the second plate portion 112 close to the opening K. The second side plate B2 includes a third plate portion 113 and a fourth plate portion 114, and the third plate portion 113 is located on the side of the fourth plate portion 114 close to the opening K. The connecting plate B3 includes a fifth plate portion 115 and a sixth plate portion 116, and the fifth plate portion 115 is located on the side of the sixth plate portion 116 close to the opening K. The thickness of the first plate portion 111 is greater than the thickness of the second plate portion 112; and / or the thickness of the third plate portion 113 is greater than the thickness of the fourth plate portion 114; and / or the thickness of the fifth plate portion 115 is greater than the thickness of the sixth plate portion 116.

[0171] The number of the first side panels B1 can be one or more, and the number can be set according to the shape of the housing 11. Similarly, the number of the second side panels B2 can be one or more, and the number can be set according to the shape of the housing 11. And according to the specific shape of the housing 11, the outer surface size of the first side panel B1 can be larger than the outer surface size of the second side panel B2, or the outer surface size of the first side panel B1 can be smaller than or equal to the outer surface size of the second side panel B2.

[0172] The first side panel B1 and the second side panel B2 are arranged on different sides of the opening K, and the connecting panel B3 is used to connect the first side panel B1 and the second side panel B2. Further, the connecting panel B3 includes an arc structure. Optionally, the outer surface of the connecting panel B3 may include an arc surface, and the inner surface of the connecting panel B3 may also include an arc surface. The number of connecting panels B3 is usually determined by the first side panel B1 and the second side panel B2. If the shell 11 only includes the first first side panel B1 and the second side panel B2, the number of connecting panels B3 is one. If the shell 11 includes a first side panel B1 and two second side panels B2 at the same time, the number of connecting panels B3 is two, and they are respectively located on both sides of the first side panel B1. If the shell 11 includes two first side panels B1 and two second side panels B2 at the same time, the number of connecting panels B3 is four, and the four connecting panels B3 are used to realize the end-to-end connection of the two first side panels B1 and the two second side panels B2 in sequence.

[0173] The first side plate B1 includes a first plate portion 111 and a second plate portion 112. The thickness of the first plate portion 111 may be greater than the thickness of the second plate portion 112, or the thickness of the first plate portion 111 may be equal to the thickness of the second plate portion 112. The second side plate B2 includes a third plate portion 113 and a fourth plate portion 114. The thickness of the third plate portion 113 may be greater than the thickness of the fourth plate portion 114, or the thickness of the third plate portion 113 may be equal to the thickness of the fourth plate portion 114. The connecting plate B3 includes a fifth plate portion 115 and a sixth plate portion 116. The thickness of the fifth plate portion 115 may be greater than the thickness of the sixth plate portion 116, or the thickness of the fifth plate portion 115 may be equal to the thickness of the sixth plate portion 116.

[0174] Due to the existence of the molten pool structure R, other positions near the position of the molten pool structure R are relatively weak structures. Specifically, there will be a weak area in at least one of the first plate portion 111, the third plate portion 113, and the fifth plate portion 115. On this basis, the embodiment of the present application adjusts the thickness of the first plate portion 111, the third plate portion 113, and the fifth plate portion 115, so that the size of at least one of the first plate portion 111, the third plate portion 113, and the fifth plate portion 115 is relatively increased, thereby improving the structural reliability of the battery cell 600.

[0175] Exemplarily, if there is a weak area only in the first plate portion 111, the first plate portion 111 can be thickened, and there is no need to thicken the third plate portion 113 and the fifth plate portion 115. At this time, the thickness of the first plate portion 111 is greater than the thickness of the third plate portion 113 and the thickness of the fifth plate portion 115.

[0176] Alternatively, in some other optional embodiments, two of the first plate portion 111 , the third plate portion 113 and the fifth plate portion 115 may be selectively thickened so that the thickness of the two plate portions is greater than the thickness of the remaining plate portion.

[0177] Alternatively, in other embodiments, the first plate portion 111, the third plate portion 113 and the fifth plate portion 115 may all be thickened at the same time. However, depending on different usage requirements, the corresponding thickening sizes of the first plate portion 111, the third plate portion 113 and the fifth plate portion 115 may be the same, or may be different, so as to better match the strength requirements of different plate portions and make the strengths of the three plate portions as consistent as possible.

[0178] In the embodiment of the present application, according to the different locations of the weak areas on the shell 11, at least one of the first plate portion 111, the third plate portion 113 and the fifth plate portion 115 can be selectively thickened to reinforce the strength of the shell 11. At the same time, compared with the overall thickening solution, the embodiment of the present application is only partially thickened, which helps to reduce material waste and space occupation of the electrode assembly 20.

[0179] It should be noted that, although the first plate portion 111 is located on the side of the second plate portion 112 close to the opening K, the side of the first plate portion 111 away from the second plate portion 112 may be provided with other plate structures, or may not be provided with other plate structures. Optionally, the side of the first plate portion 111 away from the second plate portion 112 may be provided with a plate structure with a smaller thickness, and the inner surface of the plate structure is concave relative to the inner surface of the first plate portion 111 to form a recess, which can be used to accommodate the end cover 12 to reduce the difficulty of assembling the housing 11 and the end cover 12.

[0180] In some embodiments, the thickness of the first plate portion 111 is greater than the thickness of the second plate portion 112, the thickness of the third plate portion 113 is greater than the thickness of the fourth plate portion 114, and the thickness difference between the first plate portion 111 and the second plate portion 112 is the same as the thickness difference between the third plate portion 113 and the fourth plate portion 114; and / or, the thickness of the first plate portion 111 is greater than the thickness of the second plate portion 112, the thickness of the fifth plate portion 115 is greater than the thickness of the sixth plate portion 116, and the thickness difference between the first plate portion 111 and the second plate portion 112 is the same as the thickness difference between the fifth plate portion 115 and the sixth plate portion 116.

[0181] In the embodiment of the present application, the thickness difference between the first plate portion 111 and the second plate portion 112 is the thickened dimension of the first plate portion 111 relative to the second plate portion 112. On this basis, by setting the thickened dimension of the first plate portion 111 equal to the thickened dimension of the third plate portion 113, the difficulty of preparing the first plate portion 111 and the third plate portion 113 can be reduced. Alternatively, the thickened dimension of the first plate portion 111 can be set equal to the thickened dimension of the fifth plate portion 115, which helps to reduce the difficulty of preparing the first plate portion 111 and the fifth plate portion 115.

[0182] In some embodiments, the housing 11 includes a first plate portion 111 , the first plate portion 111 is fixed to the end cover 12 , and the thickness of the end cover body 121 is greater than the thickness of the first plate portion 111 .

[0183] Combination Figure 8 For example, the thickness of the end cap body 121 refers to the dimension L3 of the end cap body 121 in the first direction X, and the thickness of the first plate portion 111 refers to the dimension H2 of the first plate portion 111 in the second direction Y. In the embodiment of the present application, since the thickness of the end cap body 121 is greater than the thickness of the first plate portion 111, the end cap body 121 can have greater structural strength than the first plate portion 111. On this basis, the embodiment of the present application changes the morphology of the molten pool structure R by changing the welding method, so that at least part of the relatively fragile area near the molten pool structure R can be located on the end cap body 121, which helps to reduce the risk of cracks or even fractures in the relatively fragile area near the molten pool structure R, and improves the reliability and service life of the battery cell 600.

[0184] Second, see Figure 6 and Fig.12 The embodiment of the present application provides an end cover 12 of a battery cell 600, including an end cover body 121 and a protrusion 122. The protrusion 122 is arranged to protrude from the outer peripheral surface of the end cover body 121 and is used to overlap the shell 11. The protrusion 122 and the end cover body 121 are both used to be welded to the shell 11 of the battery cell 600 to form a molten pool structure R.

[0185] In the embodiment of the present application, in addition to the protrusion 122 in the end cover 12, the end cover body 121 can also be used to form the molten pool structure R, which helps to further improve the welding strength between the shell 11 and the end cover 12, and improve the reliability of the battery cell 600. At the same time, the relatively weak area near the molten pool structure R will be located on the shell 11 or the end cover body 121, rather than on the protrusion 122, reducing the risk of cracks or even fractures on the protrusion 122 due to the small size of the protrusion 122, and further improving the reliability and service life of the battery cell 600.

[0186] In a third aspect, an embodiment of the present application provides a battery, comprising a battery cell 600 in any of the aforementioned embodiments.

[0187] It should be noted that the battery provided in the embodiment of the present application has the beneficial effects of the battery cell 600 in any of the aforementioned embodiments. For details, please refer to the aforementioned description of the beneficial effects of the battery cell 600, and the embodiment of the present application will not be repeated here.

[0188] In some embodiments, see Fig.10 and Fig.11 The battery further includes a heat-insulating pad 30 disposed between adjacent battery cells 600. The housing 11 includes a first plate portion 111 and a second plate portion 112. The first plate portion 111 is located on a side of the second plate portion 112 close to the opening K, and the outer circumference of the first plate portion protrudes from the outer circumference of the second plate portion. The projection of at least part of the structure of the heat-insulating pad 30 in the first direction X is located between the projections of two adjacent first plate portions 111 in adjacent battery cells 600 in the first direction X.

[0189] In combination with the foregoing, it can be known that by setting the outer circumferential surface of the first plate portion 111 to protrude from the outer circumferential surface of the second plate portion 112, the thickness of the first plate portion 111 can be made greater than the thickness of the first plate portion 111, thereby improving the welding strength between the shell 11 and the end cover 12.

[0190] On this basis, in order to reduce the risk of collision and damage between the first plate portions 111 corresponding to different battery cells 600, the embodiment of the present application also provides an insulation pad 30 between adjacent battery cells 600, and the projection of at least part of the structure in the insulation pad 30 in the first direction X can be located between the projections of the first plate portions 111 in different battery cells 600 in the first direction X, so that the first plate portions 111 corresponding to different battery cells 600 can be separated by the insulation pad 30, thereby reducing the risk of collision and damage between the first plate portions 111 corresponding to different battery cells 600.

[0191] In some embodiments, in the first direction X, at least part of the structure of the first plate portion 111 is located on one side of the thermal insulation pad 30. And / or, a recess A is provided on the thermal insulation pad 30, and the first plate portion 111 is at least partially embedded in the recess A.

[0192] In the first direction X, at least part of the structure in the first plate portion 111 is located on one side of the thermal insulation pad 30, that is, at least part of the structure in the first plate portion 111 and the thermal insulation pad 30 are located at different heights in the first direction X. Optionally, as Fig.11As shown, all structures in the first plate portion 111 are located on one side of the thermal insulation pad 30 in the first direction. This design can not only realize the spacing between different first plate portions 111 with the help of the thermal insulation pad 30, but also avoid the thermal insulation pad 30 and the first plate portion 111, thereby reducing the risk of stress concentration between different first plate portions 111.

[0193] Or Fig.15 As shown, a recess A may also be provided on the thermal insulation pad 30, and the first plate portion 111 is at least partially embedded in the recess A. The existence of the recess A can also achieve the effect of avoiding the first plate portion 11. At the same time, this design allows part of the structure in the thermal insulation pad 30 to be clamped between adjacent first plate portions 111, thereby further reducing the risk of contact and collision between different first plate portions 111.

[0194] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising a battery cell 600 in any of the aforementioned embodiments, and the battery cell 600 is used to provide electrical energy.

[0195] According to some embodiments of the present application, please refer to Figure 4 , Figure 5 , Figure 8 , Fig.12 as well as Fig.13 The battery cell 600 includes a shell 11, an electrode assembly 20 and an end cap 12. The shell 11 has an opening K at the end in the first direction X, and the electrode assembly 20 is accommodated in the shell 11. The shell 11 includes a first side plate B1, a second side plate B2 and a connecting plate B3 connecting the first side plate B1 and the second side plate B2 arranged in a circumferential direction, and the connecting plate B3 includes an arc structure. The first side plate B1 includes a first plate portion 111 and a second plate portion 112, and the first plate portion 111 is located on a side of the second plate portion 112 close to the opening K. The second side plate B2 includes a third plate portion 113 and a fourth plate portion 114, and the third plate portion 113 is located on a side of the fourth plate portion 114 close to the opening K. The connecting plate B3 includes a fifth plate portion 115 and a sixth plate portion 116, and the fifth plate portion 115 is located on a side of the sixth plate portion 116 close to the opening K. The thickness of the first plate portion 111 is greater than that of the second plate portion 112 , and there is a thickness difference between at least two of the first plate portion 111 , the third plate portion 113 , and the fifth plate portion 115 .

[0196] The end cover 12 is used to cover the opening K. The end cover 12 includes an end cover body 121 located in the projection of the opening K along the first direction X, and a protrusion 122 protruding from the end cover body 121 along the radial direction Y of the opening K. The end cover 12 is welded to the first plate portion 111 and forms a molten pool structure R. In the radial direction Y of the opening K, the molten pool structure R is exposed on the outer surface of the shell 11 and penetrates into the interior of the end cover body 121. In the direction from the outer surface of the shell 11 to the inner surface of the shell 11, the size of the molten pool structure R tends to gradually decrease. The molten pool structure R includes a first edge E1 and a second edge E2 opposite to each other in the first direction X. The first edge E1 is located in the first plate portion 111, and the second edge E2 is located in the end cover body 121.

[0197] The molten pool structure R is arranged beyond the inner surface of the first plate portion 111 . In the radial direction Y, the maximum size of the molten pool structure R is H1 , and the size of the first plate portion 111 is H2 . H1 and H2 satisfy: H2+15mm≤H1≤3mm.

[0198] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: A housing, wherein an end of the housing in a first direction has an opening; an electrode assembly, contained in the housing; An end cover, used to cover the opening, the end cover comprising an end cover body, the projection of the end cover body along the first direction is located within the projection of the opening along the first direction, and the end cover is welded to the shell to form a molten pool structure; In the radial direction of the opening, the molten pool structure is exposed on the outer surface of the shell and penetrates into the interior of the end cover body.

2. The battery cell according to claim 1, characterized in that: In the radial direction of the opening and in the direction from the outer surface of the shell to the inner surface of the shell, the size of the molten pool structure in the first direction tends to gradually decrease.

3. The battery cell according to claim 1, characterized in that: The shell includes a first plate portion, the first plate portion is fixed to the end cover, and the molten pool structure is arranged beyond the inner surface of the first plate portion; In the radial direction of the opening, the maximum size of the molten pool structure is H1, the size of the first plate portion is H2, and H1 and H2 satisfy: H2+0.15mm≤H1≤3mm.

4. The battery cell according to claim 1, characterized in that: The shell includes a first plate portion, which is fixed to the end cover. In the radial direction of the opening, the dimension of the molten pool structure extending from the outer surface of the end cover body to the outer surface of the first plate portion is H3, and the dimension of the first plate portion is H2. H2 and H3 satisfy: H3≤H2+0.5mm.

5. The battery cell according to claim 1, characterized in that: The shell includes a first plate portion, the first plate portion is fixed to the end cover, and the molten pool structure extends to an upper surface of the end cover away from the shell; In the radial direction of the opening, the size of the first plate portion is H2. In the first direction, the maximum size of the molten pool structure is L1, and the maximum size of the end cover body is L3. L1, L3 and H2 satisfy: L1≤L3+2H2.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The shell comprises a first plate portion and a second plate portion, the first plate portion is located on a side of the second plate portion close to the opening, and the molten pool structure portion is located in the first plate portion; The thickness of the first plate portion is greater than the thickness of the second plate portion.

7. The battery cell according to claim 6, characterized in that: In the first direction, the first plate portion is located on a side of the electrode assembly facing the opening.

8. The battery cell according to claim 6, characterized in that: The inner surface of the first plate portion is arranged beyond the inner surface of the second plate portion. In the first direction, the size of the first plate portion is L5, and L5 satisfies: L5≤10 mm.

9. The battery cell according to claim 6, characterized in that: The outer surface of the first plate portion is arranged beyond the outer surface of the second plate portion. In the first direction, the size of the first plate portion is L5, and L5 satisfies: L5≤15 mm.

10. The battery cell according to claim 6, characterized in that: The thickness of the first plate portion is H2, the thickness of the second plate portion is H4, and H2 and H4 satisfy: H2≤1.8H4.

11. The battery cell according to claim 6, characterized in that: The structure of the molten pool structure located inside the shell does not exceed the first plate portion.

12. The battery cell according to claim 1, characterized in that: The housing comprises a first side plate, a second side plate and a connecting plate connecting the first side plate and the second side plate, wherein the connecting plate comprises an arc structure; The first side plate includes a first plate portion and a second plate portion, the first plate portion is located on a side of the second plate portion close to the opening, the second side plate includes a third plate portion and a fourth plate portion, the third plate portion is located on a side of the fourth plate portion close to the opening, the connecting plate includes a fifth plate portion and a sixth plate portion, the fifth plate portion is located on a side of the sixth plate portion close to the opening; Wherein, the thickness of the first plate portion is greater than the thickness of the second plate portion; and / or, the thickness of the third plate portion is greater than the thickness of the fourth plate portion; and / or, the thickness of the fifth plate portion is greater than the thickness of the sixth plate portion.

13. The battery cell according to claim 12, characterized in that: The thickness of the first plate portion is greater than the thickness of the second plate portion, the thickness of the third plate portion is greater than the thickness of the fourth plate portion, and the difference in thickness between the first plate portion and the second plate portion is the same as the difference in thickness between the third plate portion and the fourth plate portion; and / or, The thickness of the first plate portion is greater than that of the second plate portion, the thickness of the fifth plate portion is greater than that of the sixth plate portion, and the thickness difference between the first plate portion and the second plate portion is the same as the thickness difference between the fifth plate portion and the sixth plate portion.

14. The battery cell according to claim 1, characterized in that: The shell includes a first plate portion, the first plate portion is fixed to the end cover, and the thickness of the end cover body is greater than the thickness of the first plate portion.

15. An end cap of a battery cell, characterized in that: include: End cap body; The protrusion is arranged to protrude from the outer peripheral surface of the end cover body and is used to overlap the shell of the battery cell. The protrusion and the end cover body are both used to be welded to the shell of the battery cell to form a molten pool structure.

16. A battery, characterized in that: Comprising the battery cell according to any one of claims 1 to 14.

17. The battery according to claim 16, characterized in that It also includes a heat insulation pad disposed between adjacent battery cells, the housing includes a first plate portion and a second plate portion, the first plate portion is located on a side of the second plate portion close to the opening, and an outer peripheral surface of the first plate portion protrudes from an outer peripheral surface of the second plate portion; The projection of at least part of the structure of the thermal insulation pad in the first direction is located between the projections of two adjacent first plate portions in adjacent battery cells in the first direction.

18. The battery according to claim 17, characterized in that In the first direction, at least part of the structure of the first plate portion is located on one side of the thermal insulation pad; and / or, The thermal insulation pad is provided with a recessed portion, and the first plate portion is at least partially embedded in the recessed portion.

19. An electrical device, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 14, wherein the battery cell is used to provide electrical energy.

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