End cover, battery cell, battery, and electric device

Abstract

An end cover (12), a battery cell (600), a battery (100), and an electric device. The battery cell (600) comprises a housing (11), an electrode assembly (20), and the end cover (12). An opening (K) is formed at the end portion of the housing (11) in a first direction (X). The electrode assembly (20) is accommodated in the housing (11). The end cover (12) is used for covering the opening (K), the end cover (12) comprises an end cover body (121) of which the projection is located in the projection of the opening (K) in the first direction (X), and the end cover (12) is welded to the housing (11) to form a molten pool structure (R). In a radial direction (Y) of the opening (K), the molten pool structure (R) is exposed on the outer surface of the housing (11) and extends into the interior of the end cover body (121). The laser is irradiated from the outer peripheral side of the housing (11) to the vicinity of the junction between the housing (11) and a protruding portion (122) in the radial direction (Y), such that the formed molten pool structure (R) can comprise most of the structures and even all of the structures of the protruding portion (122), a part of the structure of the housing (11), and a part of the structure of the end cover body (121), thereby increasing the overall size of the molten pool structure (R) and improving the welding strength between the housing (11) and the end cover (12).

Description

End caps, battery cells, batteries and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202322940675.1, filed on October 31, 2023, entitled “End cover, battery cell, battery and electrical device,” the entire contents of which are incorporated herein by reference. Technical Field

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

[0004] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and power tools. Battery cells can include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells.

[0005] 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 rupturing and affecting the reliability of the battery cell.

[0006] Summary of the Invention

[0007] 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.

[0008] In one aspect, embodiments of the present application provide a battery cell comprising a housing, an electrode assembly, and an end cap. The housing has an opening at an end in a first direction, and the electrode assembly is housed within the housing. The end cap is used to cover the opening and includes an end cap body positioned within a projection of the opening along the first direction. The end cap is welded to the housing 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 housing and extends into the interior of the end cap body.

[0009] In the above solution, the laser is directed radially from the outer periphery of the shell to the vicinity of the interface between the shell and the end cap. This design allows the resulting molten pool structure to penetrate deep into the interior of the end cap body. That is, the molten pool structure can include portions of the end cap body, thereby increasing the overall size of the molten pool structure and improving the weld strength between the shell and the end cap. It also allows at least a portion of the relatively fragile region near the molten pool structure to be located on the end cap body. Since the end cap body is typically thicker and stronger, this helps reduce the risk of cracks or even fractures in the relatively fragile region near the molten pool structure, thereby improving the reliability and service life of the battery cells.

[0010] In some embodiments, the size of the molten pool structure tends to gradually decrease in a direction from the outer surface of the shell to the inner surface of the shell.

[0011] Compared to the related art solution in which the molten pool structure extends deep into the interior of the housing along the first direction, this design reduces the impact of the molten pool structure on the housing, thereby reducing the exposed size of the molten pool structure at the housing's outer surface, improving the smoothness of the housing's outer surface, and enhancing the appearance of the battery cell. Furthermore, the size of the molten pool structure gradually decreases in the direction from the housing's outer surface toward the housing's inner surface, thereby helping to reduce the size of the molten pool structure extending deep into the center of the end cap body. This reduces the impact of the molten pool structure on the central portion of the end cap body and improves the structural reliability of the end cap body.

[0012] In some embodiments, the housing includes a first plate portion secured to the end cap, and the molten pool structure is disposed beyond an inner surface of the first plate portion. In a radial direction of the opening, the molten pool structure has a maximum dimension H1, and a dimension H2 of the first plate portion, where H1 and H2 satisfy the following: H2 + 0.15 mm ≤ H1 ≤ 3 mm.

[0013] In the above solution, H1 is set to no less than H2 + 0.15mm, allowing the molten pool structure to penetrate deep into the end cap body, thereby achieving weld fusion between the end cap body and the first plate portion and improving the reliability of the battery cell. Furthermore, in this embodiment of the application, H1 is set to no more than 3mm to reduce the risk of excessive welding energy input due to excessive penetration of the molten pool structure, resulting in severe deformation of the shell after welding, thereby improving the reliability of the shell structure in the battery cell.

[0014] In some embodiments, in the radial direction of the opening, 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+0.5mm.

[0015] 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 no more 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 at the same time 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.

[0016] In some embodiments, the housing includes a first plate portion secured to the end cap, and the molten pool structure extends to the upper surface of the end cap, distal from the housing. In the radial direction of the opening, the first plate portion has a dimension H2. In the first direction, the maximum dimension of the molten pool structure is L1, and the maximum dimension of the end cap body is L3. L1, L3, and H2 satisfy the following: L1 ≤ L3 + 2H2.

[0017] In the above scheme, L1 is set to 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 parts such as the electrode assembly, and improve the preparation yield of the battery cell.

[0018] 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 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.

[0019] In the above solution, the structure of the shell is adjusted so that the thickness of the first plate portion of 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.

[0020] In some embodiments, in the first direction, the first plate portion is located on a side of the electrode assembly facing the opening.

[0021] In the above solution, 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.

[0022] In some embodiments, 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.

[0023] 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, and further reducing the probability of lithium plating problems, thereby improving the reliability of the battery cell.

[0024] In some embodiments, 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.

[0025] In the above solution, the size of the first plate portion in the first direction is limited so that L5 is no larger than 15 mm, thereby reducing the risk of the protruding portion of the first plate portion colliding with other external components and improving the reliability of the battery cell.

[0026] 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.

[0027] In the above solution, by setting the thickness H2 of the first plate portion greater than the thickness H4 of the second plate portion, the weld strength between the housing and the end cap is improved, thereby enhancing the reliability of the battery cell. Furthermore, by setting H2 to no greater than 1.8H4, the moldability of the first and second plate portions is ensured, reducing the difficulty of housing production.

[0028] In some embodiments, the structure of the molten pool structure located within the shell does not extend beyond the first plate portion.

[0029] In the above solution, the structure within the shell of the molten pool structure does not extend beyond 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 form in the first plate portion, and the resulting cracks must radially penetrate the first plate portion to cause the shell to rupture. Therefore, this design helps to reduce the crack path length corresponding to cracks caused by electrode assembly expansion near the molten pool structure, thereby improving the reliability of the battery cell.

[0030] In some embodiments, the housing includes a circumferentially arranged 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 includes an arc-shaped structure. The first side plate includes a first plate portion and a second plate portion, wherein the first plate portion is located on a side of the second plate portion closer to the opening. The second side plate includes a third plate portion and a fourth plate portion, wherein the third plate portion is located on a side of the fourth plate portion closer to the opening. The connecting plate includes a fifth plate portion and a sixth plate portion, wherein the fifth plate portion is located on a side of the sixth plate portion closer 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.

[0031] In the above scheme, depending on the location of the weak area 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 the space occupied by the electrode assembly.

[0032] 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.

[0033] In the above solution, the difference in thickness between the first and second plate sections is the thickness increase of the first plate section relative to the second plate section. Based on this, by setting the thickness increase of the first plate section equal to the thickness increase of the third plate section, the difficulty in manufacturing the first and third plate sections can be reduced. Alternatively, the thickness increase of the first plate section can be set equal to the thickness increase of the fifth plate section, which further reduces the difficulty in manufacturing the first and fifth plate sections.

[0034] In some embodiments, the housing 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.

[0035] In the embodiment of the present application, because the thickness of the end cap body is greater than that of the first plate portion, the end cap body can have greater structural strength compared to the first plate portion. Based on this, 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. This helps 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.

[0036] In a second aspect, an embodiment of the present application provides an end cover for 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 to be welded to the shell of the battery cell to form a molten pool structure.

[0037] In a third aspect, an embodiment of the present application provides a battery comprising a battery cell according to any of the aforementioned embodiments.

[0038] In some embodiments, the battery further includes a thermal 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 proximal to the opening, and the outer circumference of the first plate portion protrudes beyond the outer circumference of the second plate portion. The projection of at least a portion of the structure of the thermal insulation pad in the first direction X is located between the projections of two adjacent first plate portions of adjacent battery cells in the first direction.

[0039] 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.

[0040] In some embodiments, in the first direction, at least a portion 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 recess, and the first plate portion is at least partially embedded in the recess.

[0041] In the above solution, the spacing between different first plate portions can be achieved with the help of thermal insulation pads, thereby reducing the risk of stress concentration between different first plate portions. Fourthly, an embodiment of the present application provides an electrical device, including a battery cell according to any of the above embodiments, the battery cell is used to provide electrical energy.

[0042] 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

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. 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.

[0044] FIG1 is a schematic structural diagram of a vehicle provided in an embodiment of the present application;

[0045] FIG2 is a schematic diagram of an exploded structure of a battery provided in an embodiment of the present application;

[0046] FIG3 is a schematic structural diagram of a battery module provided in an embodiment of the present application;

[0047] FIG4 is a schematic structural diagram of a battery cell provided in an embodiment of the present application;

[0048] FIG5 is a schematic cross-sectional view of a battery cell according to an embodiment of the present application;

[0049] FIG6 is a schematic cross-sectional view of region Q in FIG5 ;

[0050] FIG7 is a schematic diagram of a partial cross-sectional structure of another battery cell provided in an embodiment of the present application;

[0051] FIG8 is a schematic diagram of a partial cross-sectional structure of another battery cell provided in an embodiment of the present application;

[0052] FIG9 is a schematic diagram of the assembly of adjacent battery cells in a battery module provided by an embodiment of the present application;

[0053] FIG10 is a schematic diagram of a partial cross-sectional structure of a battery module provided in an embodiment of the present application;

[0054] FIG11 is an enlarged structural diagram of area P in FIG10 ;

[0055] FIG12 is a schematic structural diagram of a battery cell housing provided in an embodiment of the present application;

[0056] FIG13 is an enlarged structural diagram of area O in FIG12;

[0057] FIG14 is a schematic structural diagram of an end cap provided in an embodiment of the present application;

[0058] FIG15 is a schematic diagram of a local structure of another battery provided in an embodiment of the present application.

[0059] In the accompanying drawings: 1000, vehicle; 100, battery; 200, controller; 300, motor; 400, box; 41, first box part; 42, second box part; 43, accommodating part; 500, battery module; 600, battery cell 10, shell; 11, shell; 111, first plate part; 112, second plate part; 113, third plate part; 114, fourth plate part; 115, fifth plate part; 116, sixth plate part; 12, end cover; 121, end cover body; 122, protrusion; 20, electrode assembly; 30, thermal insulation pad; K, opening; R, molten pool structure; R1, first molten pool part; A, recess; B1, first side plate; B2, second side plate; B3, connecting plate; X, first direction; Y, radial direction. DETAILED DESCRIPTION

[0060] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art 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" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0062] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0063] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0064] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0065] 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).

[0066] 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., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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 device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0067] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0068] 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.

[0069] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0070] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0071] In some embodiments, the positive electrode may be a positive electrode sheet, which 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.

[0072] 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 provided on either or both of the two facing surfaces of the positive electrode current collector.

[0073] 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 with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer 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.).

[0074] 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. 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.

[0075] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0076] As an example, the negative electrode current collector can be a metal foil, a metal foam, or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium can be used. The metal foam can be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. The composite current collector can include a polymer material base layer 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.).

[0077] 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.

[0078] 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 provided on either or both of the two facing surfaces of the negative electrode current collector.

[0079] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. 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, and lithium titanate.

[0080] 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.

[0081] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0082] 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 and mechanical stability can be selected.

[0083] 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.

[0084] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0085] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on needs. The electrolyte can be liquid, gel, or solid.

[0086] 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.

[0087] In some embodiments, the electrode assembly is a laminate structure.

[0088] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0089] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0090] In some embodiments, a 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 (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0091] 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.

[0092] 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 electrode terminals disposed on the housing through the current collecting member.

[0093] 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, and a polygonal battery. The polygonal battery is, for example, a hexagonal battery, etc. There is no special limitation in this application.

[0094] 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.

[0095] 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.

[0096] 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 housed in the case.

[0097] In some embodiments, the box body can be used as 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 crossbeam and longitudinal beam of the vehicle.

[0098] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0099] During the battery cell manufacturing process, the end caps and casing are typically welded together to form the outer shell. During battery cell use, the electrode assembly expands, subjecting the weld area to expansion stress. This can easily lead to cracking of the outer shell in the corresponding weld area, potentially causing battery cell failure and affecting reliability.

[0100] 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.

[0101] 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, laptops, electric vehicles, electric cars, ships, spacecraft, electric toys and electric tools, etc., among which spacecraft include airplanes, rockets, space shuttles and spacecraft, 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.

[0102] 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 an example.

[0103] Please refer to Figure 1, which is a simple schematic diagram of a vehicle 1000 provided in an embodiment of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 can be set inside the vehicle 1000. For example, the battery 100 can be set at the bottom, front or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can be used as an operating power source for the vehicle 1000. The vehicle 1000 can also include a controller 200 and a motor 300. The controller 200 is used to control the battery to power the motor 300. The battery can be used for starting and navigation of the vehicle 1000. Of course, the battery 100 can also be used to drive the vehicle 1000 to drive, replacing or partially replacing fuel or natural gas to provide drive for the vehicle 1000.

[0104] Figure 2 is an exploded view of a battery according to some embodiments of the present application. As shown in Figure 2 , the battery 100 includes a housing 400 and battery cells (not shown), which are housed in the housing 400.

[0105] The housing 400 is used to accommodate battery cells and can have various structures. In some embodiments, the housing 400 can include a first housing portion 41 and a second housing portion 42. The first housing portion 41 and the second housing portion 42 overlap each other, and the first housing portion 41 and the second housing portion 42 together define a housing portion 43 for accommodating battery cells. The second housing portion 42 can be a hollow structure with one end open. The first housing portion 41 is a plate-like structure. The first housing portion 41 overlaps the open side of the second housing portion 42 to form a housing with a housing portion 43. The first housing portion 41 and the second housing portion 42 can also be hollow structures with one end open. The open side of the first housing portion 41 overlaps the open side of the second housing portion 42 to form the housing 400 with a housing portion 43. Of course, the first housing portion 41 and the second housing portion 42 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0106] In the battery 100, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections. Multiple battery cells can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire battery cell structure can be housed within the housing 400. Alternatively, multiple battery cells can be first connected in series, in parallel, or in a hybrid configuration to form a battery module 500, and then the multiple battery modules 500 can be connected in series, in parallel, or in a hybrid configuration to form a single unit and housed within the housing 400.

[0107] FIG3 is a schematic structural diagram of the battery module 500 shown in FIG2 .

[0108] In some embodiments, as shown in FIG3 , there are multiple battery cells 600, which are first connected in series, parallel, or in series to form a battery module 500. The multiple battery modules 500 are then connected in series, parallel, or in series to form a whole and housed in a box.

[0109] Figure 4 is a schematic diagram of the structure of a battery cell, and Figure 5 is a schematic diagram of the internal structure of a battery cell.

[0110] Referring to Figures 4 to 6 , a battery cell 600 includes a housing 11, an electrode assembly 20, and an end cap 12. The housing 11 has an opening K at its end in the first direction X, and the electrode assembly 20 is housed within the housing 11. The end cap 12 is used to cover the opening K and 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 housing 11, forming 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 housing 11 and extends into the interior of the end cap body 121.

[0111] The housing 11 and the end cap 12 are welded together to form the outer shell 10. The outer shell 10 has a hollow structure, which is used to form a storage space for the electrode assembly 20 and other components. The end cap 12 includes an end cap body 121. Furthermore, in the embodiments of the present application, the phrase "the end cap 12 includes an end cap body 121 located within the projection of the opening K along the first direction X" means that the projection of the end cap body 121 is located within the projection of the opening K along the first direction X. The first direction X can be the thickness direction of the end cap body 121.

[0112] The electrode assembly 20 is the primary component of the battery cell 600 for providing electrical energy. The shapes of the housing 11 and end cap 12 can be determined based on the shape of the electrode assembly 20. For example, if the electrode assembly 20 is cylindrical, the housing 11 will have a cylindrical shape, and the projection of the end cap body 121 in the first direction X will be circular or quasi-circular. If the electrode assembly 20 is a rectangular parallelepiped, the housing 11 will have a rectangular shape, and the projection of the end cap body 121 in the first direction X will be rectangular or quasi-rectangular.

[0113] The end cap 12 is welded to the shell 11 and forms 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. Specifically, please refer to Figure 6, which shows the structure of the end cap 12 before welding and its relative relationship with the molten pool structure R. For example, in addition to including an end cap body 121, the end cap 12 may also include a protrusion 122, which is provided to protrude from the outer peripheral surface of the end cap body 121. At least a portion of the structure in the protrusion 122 and a portion of the structure in the end cap body 121 are used to melt into one piece with a portion of the structure in the shell 11, thereby forming the molten pool structure R.

[0114] The present embodiment does not limit the shape and size relationship between the protrusion 122 and the end cap body 121. For example, the cross-sectional shape of the protrusion 122 and the end cap body 121 can be T-shaped, and when the end cap body 121 is projected as a circle along its thickness, the projection of the protrusion 122 along the thickness of the end cap body 121 can be a circular ring structure. When the end cap body 121 is projected as a square along its thickness, the projection of the protrusion 122 along the thickness of the end cap body 121 can be a square ring structure.

[0115] In related art, laser welding can be achieved between the housing 11 and the end cap 12. The laser typically irradiates the protrusion 122 along a first direction X from the side of the end cap 12 facing away from the electrode assembly 20, causing a portion of the structure within the protrusion 122 to fuse with the housing 11 to form a molten pool structure R, thereby achieving a welded connection between the end cap 12 and the housing 11. However, this welding method typically only welds the protrusion 122 to the housing 11, while the end cap body 121 is not directly molten to the housing 11. As a result, during the use of the battery cell 600, due to the expansion of the electrode assembly 20, the areas with lower strength around the molten pool structure R, namely the interface between the protrusion 122 and the end cap body 121, are more susceptible to expansion stress. Furthermore, due to the smaller size of the protrusion 122 itself, the structural strength of the protrusion 122 is further reduced, thereby accelerating the risk of cracks or even splitting at the protrusion 122, affecting the reliability and service life of the battery cell 600.

[0116] 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. For example, 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.

[0117] In addition, the phrase "the molten pool structure R is exposed on the outer surface of the shell 11" in the embodiments of the present application means that the outer surface of the molten pool structure R can be observed on the outer circumference 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 recessed or flush with the outer surface of the shell 11, as long as the molten pool structure R can be observed on the outer circumference of the shell 11 and along the radial direction Y.

[0118] Furthermore, the molten pool structure R can penetrate deep into the interior of the end cap body 121, that is, the molten pool structure R can directly weld and fix the shell 11 to the end cap body 121. To meet the size and shape requirements of the molten pool structure R, during the welding process of the end cap 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 intersection of the shell 11 and the end cap 12, where the direction of the arrow in Figure 6 can represent the direction of laser irradiation. This design allows the formed molten pool structure R to penetrate deep into the interior of the end cap body 121, that is, the molten pool structure R can include part of the structure of the end cap 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 cap 12. At the same time, it also allows at least a portion of the relatively fragile area near the molten pool structure R to be located on the end cap body 121. Since the end cap body 121 is generally thicker and stronger, this helps 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.

[0119] In some embodiments, as shown in FIG6 , the size of the molten pool structure R tends to gradually decrease in the direction from the outer surface of the shell 11 to the inner surface of the shell 11 .

[0120] 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.

[0121] Furthermore, the molten pool structure R ultimately formed in the embodiment of the present application generally differs from the molten pool structure R in the related art. Specifically, the molten pool structure R in the embodiment of the present application extends deep into the interior of the end cap body 121 along the radial direction Y. As a result, the size of the molten pool structure R gradually decreases in the direction from the outer surface of the shell 11 toward the inner surface of the shell 11.

[0122] Compared to related art solutions in which the molten pool structure R extends deep into the interior of the housing 11 along the first direction X, this design can reduce the impact of the molten pool structure R on the housing 11, thereby reducing the exposed size of the molten pool structure R at the outer surface of the housing 11, improving the flatness of the outer surface of the housing 11, and enhancing the appearance of the battery cell 600. Furthermore, the size of the molten pool structure R gradually decreases in the direction from the outer surface of the housing 11 toward the inner surface of the housing 11. This helps reduce the structural size of the molten pool structure R extending deep into the center of the end cap body 121, thereby reducing the impact of the molten pool structure R on the central position of the end cap body 121 and improving the structural reliability of the end cap body 121.

[0123] In some embodiments, as shown in FIG6 , the housing 11 includes a first plate portion 111 , which is secured to the end cap 12 . The molten pool structure R is disposed beyond the inner surface of the first plate portion 111 . In the radial direction Y of the opening K, the maximum dimension of the molten pool structure R is H1 , and the dimension of the first plate portion 111 is H2 . H1 and H2 satisfy the following relationship: H2 + 0.15 mm ≤ H1 ≤ 3 mm.

[0124] The first plate portion 111 is located at the end of the housing 11. The first plate portion 111 can be used to enclose the opening K, wherein at least a portion of the structure of the first plate portion 111 can be welded to the end cap 12. In the radial direction Y of the opening K, the first plate portion 111 has a dimension H2, that is, a thickness H2. It should be noted that, depending on the actual needs of different battery cells 600, the thickness of the housing 11 can be consistent at all locations, or the thickness of the housing 11 can vary to some extent.

[0125] 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.

[0126] 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 penetration depth of the molten pool structure R. In combination with the foregoing, it can be seen that the molten pool structure R needs to penetrate into the interior of the end cap body 121. Therefore, 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 no less than H2+0.15mm, so that the molten pool structure R can penetrate into the interior of the end cap body 121, thereby achieving welding and melting between the end cap body 121 and the first plate portion 111, and improving the reliability of the battery cell 600.

[0127] In addition, the embodiment of the present application also sets H1 to no more than 3 mm, thereby reducing the risk of severe deformation of the shell 11 after welding due to excessive energy input during welding due to excessive penetration of the molten pool structure R, thereby improving the reliability of the shell 11 structure in the battery cell 600.

[0128] 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 cap body 121 to the outer surface of the first plate portion 111 is H3, and H2 and H3 satisfy: H3 ≤ H2 + 0.5 mm. Optionally, the value of H3 - H2 is one of 0.1 mm, 0.2 mm, 0.25 mm, 0.4 mm, and 0.5 mm.

[0129] After the shell 11 and the end cap 12 are welded and secured, the effective penetration depth in the molten pool structure R, required to achieve the weld fixation effect, corresponds to H3. During the manufacturing process of the shell 11 and the end cap 12, to meet the assembly requirements between the shell 11 and the end cap 12, the projected dimension of the end cap body 121 in the first direction X is typically set smaller than the projected dimension of the opening K in the first direction X, so that the end cap body 121 can be inserted into the opening K. Under this design, a gap exists between the outer surface of the end cap body 121 and the inner surface of the first plate portion 111 in the radial direction Y of the opening K. In other words, the effective penetration depth H3 is greater than the thickness H2 of the first plate portion 111. Furthermore, the numerical value H3-H2 represents the dimension of the gap between the end cap body 121 and the first plate portion 111 in the radial direction Y, and the value of H3-H2 generally also affects the preparation of the resulting molten pool structure R.

[0130] Specifically, during the welding process between the end cap 12 and the housing 11, part of the structure in the housing 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 housing 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. During 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 housing 11 and the liquid structure formed by the melting of the end cap 12 may fall from the gap space, easily damaging the structure of the electrode assembly 20 and detrimental to the yield rate of the battery cell 600. At the same time, the molten pool structure R may cause structural defects in the gap space, affecting the welding reliability between the end cap 12 and the housing 11, and thus easily having an adverse effect on the use of the battery cell 600.

[0131] 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 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.

[0132] In some embodiments, as shown in FIG6 , the molten pool structure R extends to the upper surface of the end cap 12 away from the housing 11. In the radial direction Y of the opening K, the first plate portion 111 has a dimension H2. In the first direction X, the maximum dimension of the molten pool structure R is L1, and the maximum dimension of the end cap body 121 is L3. L1, L3, and H2 satisfy the following: L1 ≤ L3 + 2H2.

[0133] 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.

[0134] Furthermore, the molten pool structure R extends to the upper surface of the end cap 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. The molten pool structure R can extend from the protrusion 122 to the first plate portion 111 in the first direction X. This allows at least a portion of the structure in the first plate portion 111 and at least a portion of the structure in the protrusion 122 to be melted into one, thereby improving the welding strength between the end cap 12 and the shell 11. In some optional embodiments, in the first direction X, the dimension of the protrusion is L2, where L2+0.1mm≤L1.

[0135] If the maximum dimension L1 of the molten pool structure R in the first direction X is too large, it is easy for 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 can easily have an adverse effect on the electrode assembly 20 and cause certain welding defects. In view of this, the embodiment of the present application also sets L1 to be no greater 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 parts such as the electrode assembly 20, and improve the production yield of the battery cell 600.

[0136] In summary, the embodiment of the present application sets L1 to 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 121 toward the electrode assembly 20, reduce the impact of the welding process on parts such as the electrode assembly 20, and improve the preparation yield of the battery cell 600.

[0137] In some embodiments, as shown in FIG6 , the molten pool structure R includes a first molten pool portion R1 located within the end cap 12 . The first molten pool portion R1 has a dimension L4 in the first direction X, where L4 and L2 satisfy the following relationship: L2 + 0.05 mm ≤ L4 ≤ L2 + 0.5 mm. Optionally, L4 is one of L2 + 0.05 mm, L2 + 0.1 mm, L2 + 0.2 mm, L2 + 0.3 mm, and L2 + 0.5 mm.

[0138] The first molten pool portion R1 is the 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. Furthermore, the dimension L4 of the first molten pool portion R1 in the first direction X is the effective weld width that enables the molten pool structure R to achieve a 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, and not irradiate the shell 11, which may result in the shell 11 being unable to be welded and fixed to the end cover 12, or the welding strength between the end cover 12 and the shell 11 being too low.

[0139] Given this, the embodiment of the present application sets L4 to no less than L2 + 0.05mm, ensuring that the laser can illuminate the housing 11 within the tolerance of the top cover manufacturing process, thereby achieving simultaneous melting welding of the housing 11 and the end cap 12, and improving the weld strength between the two. Furthermore, the embodiment of the present application sets L4 to no more than L2 + 0.5mm, reducing the risk of severe deformation of the housing 11 after welding due to excessive energy input during welding caused by an oversized first molten pool portion R1, thereby improving the reliability of the housing 11 structure in the battery cell 600.

[0140] In some embodiments, please refer to 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 the 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, and the thickness of the first plate portion 111 is greater than the thickness of the second plate portion 112.

[0141] The first plate portion 111 and the second plate portion 112 are arranged side by side in the first direction X. The first plate portion 111 and the second plate portion 112 have different thicknesses, that is, the first plate portion 111 and the second plate portion 112 have different dimensions in the radial direction Y of the opening K. Specifically, the inner surface of the first plate portion 111 facing the electrode assembly 20 may be arranged to protrude outward relative to the inner surface of the second plate portion 112 facing the electrode assembly 20, such 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 facing away from the electrode assembly 20 may be arranged to protrude outward relative to the outer surface of the second plate portion 112 facing away from the electrode assembly 20, such that the thickness of the first plate portion 111 is greater than the thickness of the second plate portion 112.

[0142] 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 the transition and fixation of the first plate portion 111 and the second plate portion 112.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] It can be seen from the above content 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.

[0147] 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.

[0148] In some embodiments, referring to FIG. 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.

[0149] 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 to extend beyond the inner surface of the second plate portion 112, thereby helping to improve the welding strength between the shell 11 and the end cover 12 and improve the reliability of the battery cell 600.

[0150] 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, so that during the expansion of the electrode assembly 20, it is easy for the electrode assembly 20 and the first plate portion 111 to have contact interference, and then it is easy for stress concentration to occur between the electrode assembly 20 and the first plate portion 111, which can easily cause lithium plating problems and affect the normal use of the battery cell 600.

[0151] 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.

[0152] 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.

[0153] In some embodiments, as shown in FIG. 7 , 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.

[0154] From the above content, 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.

[0155] 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.

[0156] 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 and interfering with other external components, thereby improving the reliability of the battery cell 600.

[0157] It should be noted that in the battery module 500, there can be one or more battery cells 600. Please refer to Figures 6, 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 provided 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.

[0158] 7 , 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.

[0159] 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 this 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 weld strength between the housing 11 and the end cap 12 is improved, thereby enhancing the reliability of the battery cell 600. Furthermore, by setting H2 to no greater than 1.8H4, the molding feasibility of the first plate portion 111 and the second plate portion 112 is ensured, reducing the difficulty of manufacturing the housing 11.

[0160] In some embodiments, as shown in FIG. 7 , the structure of the molten pool structure R located inside the shell 11 does not extend beyond the first plate portion 111 .

[0161] Typically, the housing 10 has low strength near the molten pool structure R. Furthermore, if the molten pool structure R extends into the second plate portion 112, cracks are likely to form in the second plate portion 112 when the electrode assembly 20 expands. Furthermore, because the second plate portion 112 is thinner than the first plate portion 111, cracks can easily penetrate the second plate portion 112 in the radial direction Y, completely rupturing the housing 11 and affecting the reliability of the battery cell 600.

[0162] In view of this, the embodiment of the present application does not extend the structure of the molten pool structure R within the shell 11 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 form in the first plate portion 111, and the resulting cracks need to penetrate the first plate portion 111 in the radial direction Y to cause the shell 11 to rupture. Therefore, this design helps to increase the crack path length corresponding to cracks caused by the expansion of the electrode assembly 20 near the molten pool structure R, thereby improving the reliability of the battery cell 600.

[0163] Similarly, the second edge E2 is located inside the end cover body 121 and can have a larger size than the protrusion 122 , thereby also increasing the crack path length near the second edge E2 and improving the reliability of the battery cell 600 .

[0164] In some embodiments, referring to Figures 12 and 13 , the housing 11 includes a circumferentially arranged first side panel B1, a second side panel B2, and a connecting panel B3 connecting the first and second side panels B1 and B2. The connecting panel B3 includes an arcuate structure. The first side panel B1 includes a first plate portion 111 and a second plate portion 112. The first plate portion 111 is located on the side of the second plate portion 112 near the opening K. The second side panel B2 includes a third plate portion 113 and a fourth plate portion 114. The third plate portion 113 is located on the side of the fourth plate portion 114 near the opening K. The connecting panel B3 includes a fifth plate portion 115 and a sixth plate portion 116. The fifth plate portion 115 is located on the side of the sixth plate portion 116 near the opening K. The first plate portion 111 is thicker than the second plate portion 112; and / or the third plate portion 113 is thicker than the fourth plate portion 114; and / or the fifth plate portion 115 is thicker than the sixth plate portion 116.

[0165] The number of 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 second side panels B2 can be one or more, and the number can be set according to the shape of the housing 11. Furthermore, depending on 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.

[0166] 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. Furthermore, the connecting panel B3 includes an arc-shaped 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 both a first side panel B1 and two second side panels B2, 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 both two first side panels B1 and two second side panels B2, the number of connecting panels B3 is four, and the four connecting panels B3 are used to achieve the end-to-end connection of the two first side panels B1 and the two second side panels B2.

[0167] The first side panel B1 includes a first panel portion 111 and a second panel portion 112. The thickness of the first panel portion 111 may be greater than that of the second panel portion 112, or the thickness of the first panel portion 111 may be equal to that of the second panel portion 112. The second side panel B2 includes a third panel portion 113 and a fourth panel portion 114. The thickness of the third panel portion 113 may be greater than that of the fourth panel portion 114, or the thickness of the third panel portion 113 may be equal to that of the fourth panel portion 114. The connecting panel B3 includes a fifth panel portion 115 and a sixth panel portion 116. The thickness of the fifth panel portion 115 may be greater than that of the sixth panel portion 116, or the thickness of the fifth panel portion 115 may be equal to that of the sixth panel portion 116.

[0168] Due to the presence of the molten pool structure R, other locations near the molten pool structure R are relatively weak. Specifically, a weak area may exist within at least one of the first plate portion 111, the third plate portion 113, and the fifth plate portion 115. Based on this, 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, thereby increasing the size of at least one of the first plate portion 111, the third plate portion 113, and the fifth plate portion 115, thereby improving the structural reliability of the battery cell 600.

[0169] For example, if there is an area of ​​weak strength 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.

[0170] Alternatively, in 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.

[0171] 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, but 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 strength of the three plate portions as consistent as possible.

[0172] In the embodiment of the present application, depending on the location of the weak area 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 achieve the reinforcement effect on 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 occupied by the electrode assembly 20.

[0173] It should be noted that although the first plate portion 111 is located on the side of the second plate portion 112 that is closer to the opening K, the side of the first plate portion 111 that is 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 that is away from the second plate portion 112 may be provided with a plate structure of smaller thickness, with the inner surface of this plate structure being recessed relative to the inner surface of the first plate portion 111 to form a recess. The recess can be used to accommodate the end cap 12, thereby reducing the difficulty of assembly between the housing 11 and the end cap 12.

[0174] 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.

[0175] In the embodiment of the present application, the thickness difference between the first plate portion 111 and the second plate portion 112 is the thickness increase of the first plate portion 111 relative to the second plate portion 112. Based on this, by setting the thickness increase of the first plate portion 111 equal to the thickness increase of the third plate portion 113, the difficulty in manufacturing the first and third plate portions 111, 113 can be reduced. Alternatively, the thickness increase of the first plate portion 111 can be set equal to the thickness increase of the fifth plate portion 115, which helps to reduce the difficulty in manufacturing the first and fifth plate portions 111, 115.

[0176] 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 .

[0177] With reference to FIG8 , 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, thereby helping 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.

[0178] On the second aspect, please refer to Figures 6 and 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 weld with the shell 11 of the battery cell 600 to form a molten pool structure R.

[0179] In the embodiment of the present application, in addition to the protrusion 122 of the end cap 12 being used to form the molten pool structure R, the end cap body 121 can also be used to form the molten pool structure R. This helps to further improve the weld strength between the housing 11 and the end cap 12, thereby improving the reliability of the battery cell 600. At the same time, the relatively fragile area near the molten pool structure R is located on the housing 11 or the end cap body 121, rather than on the protrusion 122. This reduces the risk of cracks or even breakage on the protrusion 122 due to its undersized size, further improving the reliability and service life of the battery cell 600.

[0180] In a third aspect, an embodiment of the present application provides a battery, comprising the battery cell 600 in any of the aforementioned embodiments.

[0181] 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, which will not be repeated in the embodiment of the present application.

[0182] In some embodiments, referring to Figures 10 and 11 , the battery further includes a thermal insulation 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 near the opening K, with the outer circumference of the first plate portion protruding beyond the outer circumference of the second plate portion. The projection of at least a portion of the thermal insulation pad 30 in the first direction X is located between the projections of two adjacent first plate portions 111 of adjacent battery cells 600 in the first direction X.

[0183] In combination with the above content, it can be seen that by setting the outer peripheral surface of the first plate portion 111 to protrude from the outer peripheral 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.

[0184] 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 a thermal insulation pad 30 between adjacent battery cells 600, and the projection of at least part of the structure in the thermal 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 means of the thermal insulation pad 30, thereby reducing the risk of collision and damage between the first plate portions 111 corresponding to different battery cells 600.

[0185] In some embodiments, in the first direction X, at least a portion 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.

[0186] 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, that is, at least part of the structure of the first plate portion 111 and the thermal insulation pad 30 are located at different heights in the first direction X. Optionally, as shown in FIG11 , all of the structure of the first plate portion 111 is located on one side of the thermal insulation pad 30 in the first direction. This design can not only achieve 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.

[0187] Alternatively, as shown in Figure 15, 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.

[0188] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising a battery cell 600 according to any of the aforementioned embodiments, wherein the battery cell 600 is used to provide electrical energy.

[0189] According to some embodiments of the present application, referring to Figures 4, 5, 8, 12, and 13, a battery cell 600 includes a housing 11, an electrode assembly 20, and an end cap 12. The housing 11 has an opening K at its end in the first direction X, and the electrode assembly 20 is housed within the housing 11. The housing 11 includes a first side plate B1, a second side plate B2, and a connecting plate B3 connecting the first and second side plates B1 and B2. The connecting plate B3 comprises an arc-shaped structure. The first side plate B1 includes a first plate portion 111 and a second plate portion 112. The first plate portion 111 is located on the side of the second plate portion 112 that is closer to the opening K. The second side plate B2 includes a third plate portion 113 and a fourth plate portion 114. The third plate portion 113 is located on the side of the fourth plate portion 114 that is closer to the opening K. The connecting plate B3 includes a fifth plate portion 115 and a sixth plate portion 116. The fifth plate portion 115 is located on the side of the sixth plate portion 116 that is closer 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 .

[0190] The end cap 12 is used to cover the opening K. It includes an end cap body 121 positioned within the projection of the opening K along the first direction X, and a protrusion 122 projecting from the end cap body 121 in the radial direction Y of the opening K. The end cap 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 extends into the interior of the end cap body 121. The size of the molten pool structure R gradually decreases in the direction from the outer surface of the shell 11 to the inner surface of the shell 11. The molten pool structure R includes a first edge E1 and a second edge E2 that oppose each other in the first direction X. The first edge E1 is positioned within the first plate portion 111, and the second edge E2 is positioned within the end cap body 121.

[0191] 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.

[0192] 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 make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions 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, comprising: 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, wherein: 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 or 2, wherein: 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 any one of claims 1 to 3, wherein: 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 any one of claims 1 to 4, wherein: 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, wherein: 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, wherein: 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 or 7, wherein: 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 any one of claims 6 to 8, wherein: 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 any one of claims 6 to 9, wherein: 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 any one of claims 6 to 10, wherein: The structure of the molten pool structure located inside the shell does not exceed the first plate portion.

12. The battery cell according to any one of claims 1 to 11, wherein: 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, wherein: 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 any one of claims 1 to 13, wherein: 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, comprising: 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, further comprising a heat insulating pad disposed between adjacent battery cells, the housing comprising a first plate portion and a second plate portion, the first plate portion being located on a side of the second plate portion close to the opening, and an outer peripheral surface of the first plate portion protruding 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, wherein 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 comprising the battery cell according to any one of claims 1 to 14, wherein the battery cell is used to provide electrical energy.

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