Battery cell, battery, electric device, and method for manufacturing battery cell

Abstract

The application provides a battery cell, a battery, a power utilization device and a preparation method of the battery cell. The battery cell comprises a shell and an electrode assembly. The shell has a containing space. The shell comprises a first plate part and a second plate part. The first plate part and the second plate part are welded to form a molten pool structure. The shell further comprises a welding gas hole in the molten pool structure. The electrode assembly is contained in the containing space. The thickness of the first plate part is greater than the thickness of the second plate part. At least part of the welding gas hole is located in the first plate part. The welding process of the first plate part and the second plate part is adjusted in the embodiment of the application, so that at least part of the welding gas hole can be located in the first plate part. Since at least part of the welding gas hole can be located in the first plate part, the welding gas holes located in the second plate part are reduced, thereby helping to reduce the influence of the welding gas holes on the strength of the second plate part and improving the use reliability of the battery cell.

Description

Battery cell, battery, electrical device and method for preparing battery cell Technical Field

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

[0002] 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.

[0003] However, during use, under the influence of factors such as internal expansion or external stress, the outer shell is prone to the risk of rupture, affecting the reliability of the battery cell.

[0004] Summary of the Invention

[0005] In view of the above problems, the present application provides a battery cell, a battery, an electrical device and a method for preparing the battery cell, which can improve the reliability of the battery cell.

[0006] In one aspect, embodiments of the present application provide a battery cell comprising a housing and an electrode assembly. The housing has a housing space and includes a first plate portion and a second plate portion. The first plate portion and the second plate portion are welded to form a molten pool structure, and welding pores are located within the molten pool structure. The electrode assembly is housed within the housing space. The first plate portion is thicker than the second plate portion, and at least some of the welding pores are located within the first plate portion.

[0007] In the above solution, the welding process for the first and second plates is adjusted so that at least some of the welding pores can be located within the first plate. Because the first plate is thicker than the second plate, the thickness of the first plate itself can still ensure that it will not crack or break under certain stresses. Furthermore, because at least some of the welding pores can be located within the first plate, the number of welding pores in the second plate is reduced, which helps to reduce the impact of welding pores on the strength of the second plate, reduces the risk of cracking or breakage in the second plate, and helps to improve the reliability of the battery cells.

[0008] In some embodiments, the molten pool structure includes a body portion and an end portion connected to the body portion and extending into the first plate portion, the body portion is exposed to the outer surface of the shell, and at least part of the welding pores is located in the end portion.

[0009] In the above scheme, compared with the main body, during the welding process, more welding pores are more easily formed in the end portion. On this basis, the embodiment of the present application can control the end portion within the first plate portion by adjusting the position relationship of the end portion relative to the outer shell, so that more welding pores can be located in the first plate portion, thereby reducing the risk of cracking of the outer shell due to the presence of welding pores and improving the reliability of the battery cell.

[0010] In some embodiments, the second plate portion includes a first surface facing the electrode assembly, and in the thickness direction of the first plate portion, the minimum distance between the welding pores located in the end portion and the first surface is L1, and L1 satisfies: 0.1mm≤L1≤5mm.

[0011] In the above solution, by adjusting the welding method, the minimum distance L1 between the weld pores in the end portion and the first surface can be no less than 0.1 mm. This reduces the impact of the weld pores in the end portion on the strength of the second plate portion, reduces the risk of cracking and damage in the second plate portion of the battery cell, and improves the structural reliability of the battery cell.

[0012] In some embodiments, the end portion is spaced apart from the second plate portion in a thickness direction of the second plate portion.

[0013] In the above scheme, by adjusting the welding method, the end portion and the second plate portion can be spaced apart, thereby further reducing the impact of the internal welding pores of the end portion on the second plate portion, further reducing the risk of cracking and damage of the second plate portion, and improving the structural reliability of the battery cell.

[0014] In some embodiments, the first plate portion is located at one side of the electrode assembly along a first direction, and the end portion is located at one side of the body portion along a second direction, and the first direction intersects the second direction.

[0015] In the above scheme, by tilting the laser incident direction during welding compared to the thickness direction of the first plate portion, the end portion can be located on one side of the main body portion along the second direction, which helps to make the end portion be further deviated from the second plate portion, thereby reducing the impact of the internal welding pores of the end portion on the second plate portion, further reducing the risk of cracking and damage to the second plate portion, and improving the structural reliability of the battery cell.

[0016] In some embodiments, the first plate portion has a central portion and an edge portion located on the periphery of the central portion, the edge portion is welded to the second plate portion, and in the thickness direction of the second plate portion, the end portion protrudes relative to the main body portion toward the central portion to form a molten pool structure.

[0017] In the above solution, the edge portion is positioned closer to the second plate portion than the center portion, and the edge portion needs to be welded to the second plate portion, meaning the molten pool structure is typically located within the edge portion. Based on this, in the embodiment of the present application, the end portion protrudes toward the center portion relative to the main body portion, meaning the end portion is positioned further away from the second plate portion than the main body portion. This helps increase the distance between the end portion and the second plate portion, thereby reducing the impact of weld pores within the end portion on the second plate portion and improving the reliability of the housing structure.

[0018] In some embodiments, the housing includes a shell and an end cover, the shell has an opening at at least one end in the first direction, the end cover is used to cover the opening, the end cover includes a first plate portion, and the shell includes a second plate portion.

[0019] By controlling the welding method, at least part of the welding pores can be located in the first plate portion, that is, at least part of the welding pores can be located in the end cover rather than in the shell, thereby reducing the impact of the welding pores on the strength of the shell, reducing the risk of cracking and damage to the shell, and improving the reliability of the battery cell.

[0020] In some embodiments, a recess is provided on the inner surface of the housing near the opening, and the end cap is at least partially located within the recess and welded to the side of the recess. Alternatively, the end cap includes an end cap body and a protrusion disposed around the end cap body, the end cap body being disposed corresponding to the opening, and the protrusion being located on one side of the housing along the first direction and welded to the housing.

[0021] The above solution can be applied to various welding methods, such as top welding and side welding, making it suitable for different types of housing structures and providing strong flexibility. Furthermore, by locally adjusting the welding method, at least some of the welding pores can be adjusted to the first plate portion, thereby improving the reliability of the battery cell.

[0022] In some embodiments, the molten pool structure includes a weld print structure exposed on the outer surface of the shell, the end cover is accommodated in the opening, and the weld print structure is at least partially exposed on the upper surface of the end cover; and / or, a portion of the structure in the end cover is overlapped with the shell in a first direction, and the weld print structure is at least partially exposed on the outer surface of the shell.

[0023] In the above scheme, the weld mark structure formed will vary depending on the welding method. On this basis, by adjusting and changing the welding method, at least part of the welding pores can be located in the first plate part, thereby reducing the risk of cracking and damage in the second plate part, and having strong flexibility and reliability.

[0024] In a second aspect, embodiments of the present application provide a battery comprising a battery cell according to any of the aforementioned embodiments. In some embodiments, the structure of the molten pool structure located within the housing does not extend beyond the first plate portion.

[0025] In a third aspect, an embodiment of the present application provides an electrical device, which includes a battery cell according to any of the aforementioned embodiments.

[0026] In a fourth aspect, an embodiment of the present application provides a method for preparing a battery cell, the method comprising:

[0027] Providing a first plate portion and a second plate portion, wherein the thickness of the first plate portion is greater than the thickness of the second plate portion;

[0028] The first plate portion and the second plate portion are welded by laser irradiation to form a molten pool structure penetrating into the first plate portion, so that at least part of the welding pores are located in the first plate portion.

[0029] In the above solution, by adjusting the welding process, the molten pool structure formed by welding can penetrate deep into the first plate portion, thereby allowing at least some of the welding pores to be located in the second plate portion. Since the first plate portion itself has a certain thickness, even if welding pores exist in the first plate portion, the thickness of the first plate portion itself can still ensure that it will not crack or break under the influence of certain stresses. Furthermore, since at least some of the welding pores can be located in the first plate portion, the number of welding pores located in the second plate portion is reduced, which helps to reduce the impact of welding pores on the strength of the second plate portion, reduces the risk of cracking or breakage in the second plate portion, and helps to improve the reliability of the battery cell.

[0030] In some embodiments, the end cover includes a first plate portion, the housing includes a second plate portion, at least one end of the housing in the first direction has an opening, and the end cover is used to cover the opening.

[0031] In the above scheme, by adjusting the welding method, the molten pool structure formed by welding can be able to penetrate into the end cover, so that at least part of the welding pores can be located in the end cover, thereby reducing the number of welding pores located in the shell, thereby helping to reduce the impact of the welding pores on the strength of the shell, reducing the risk of cracking and damage to the shell, and helping to improve the reliability of the battery cell.

[0032] In some embodiments, in welding the first plate portion and the second plate portion using laser irradiation, the laser is irradiated on a surface of at least one of the end cap and the housing in the first direction;

[0033] wherein the incident angle of the laser intersects the first direction; and / or,

[0034] The position where the laser irradiates the surface of the end cover is spaced apart from the inner surface of the shell.

[0035] In the above scheme, based on the top welding process, the incident position of the top welding relative to the shell and the end cover, and at least one of the incident angles are adjusted, which helps to enable at least part of the welding pores to be located inside the end cover, reduce the adverse effects of the welding pores on the shell, and improve the reliability of the battery cell.

[0036] In some embodiments, when welding the first plate portion and the second plate portion using laser irradiation, the laser is irradiated to the outer surface of at least one of the shell and the end cover in a third direction, where the third direction intersects with the first direction and is parallel to the thickness direction of the second plate portion.

[0037] In the above scheme, the side welding method is used so that the end of the molten pool structure formed by welding can extend into the end cover, so that the welding pores in the end can be located inside the end cover, reducing the impact of the welding pores on the shell and improving the structural reliability of the battery cell.

[0038] In some embodiments, the thickness of the second plate portion is T, the size of the molten pool structure in the first direction is H, the angle between the laser irradiation angle and the first direction is β, and β satisfies: 90°-arcsin(T / H)≤β≤90°+arcsin(T / H).

[0039] In the above scheme, whether top welding or side welding is adopted, in order to allow the end of the molten pool structure to penetrate into the end cover, the laser irradiation angle needs to be limited. Among them, by setting the laser irradiation angle to intersect with the first direction, and the angle β between the two is set to be not less than 90°-arcsin (T / H), the risk of excessive welding pores in the shell due to excessive structures in the molten pool structure being located inside the shell, thereby reducing the risk of cracking and damage. Furthermore, the embodiment of the present application also sets the angle β to be no greater than 90°-arcsin (T / H) to reduce the risk of the molten pool structure penetrating into the center of the end cover, reduce the adverse effects of the molten pool structure on the end cover, and improve the reliability of the battery cell.

[0040] In some embodiments, β satisfies: 7°≤β≤173°.

[0041] In the above solution, by setting β to no less than 7°, the risk of excessive weld porosity in the shell, which could lead to cracking and damage, due to excessive structure within the molten pool structure being located within the shell is reduced. Furthermore, in this embodiment of the application, the angle β is set to no greater than 173° to reduce the risk of the molten pool structure penetrating into the center of the end cap, thereby reducing the adverse effects of the molten pool structure on the end cap and improving the reliability of the battery cell.

[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 diagram of an exploded structure 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 diagram of a partial cross-sectional structure of a battery cell provided in an embodiment of the present application;

[0049] FIG6 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in an embodiment of the present application;

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

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

[0052] FIG9 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in an embodiment of the present application;

[0053] FIG10 is a flow chart of a method for preparing a battery cell provided in an embodiment of the present application.

[0054] In the attached figure:

[0055] 1000. Vehicle;

[0056] 100, battery; 200, controller; 300, motor; 400, housing; 41, first housing portion; 42, second housing portion; 43, storage portion; 500, battery module; 600, battery cell;

[0057] 10. Housing; 11. End cap; 111. First plate portion; 1111. Center portion; 1112. Edge portion; 112. End cap body; 113. Protrusion; 12. Housing; 121. Second plate portion; 1211. First surface;

[0058] 20. Electrode assembly;

[0059] 30. Molten pool structure; 31. Main body; 32. End;

[0060] K, opening;

[0061] A. concave part;

[0062] J. Welding and printing structure;

[0063] H. Welding pores;

[0064] X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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).

[0071] 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.

[0072] 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.

[0073] In the embodiment of the present application, the battery cell may be a secondary battery cell. A secondary battery cell refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0074] The battery cell can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-hydrogen battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc., and the embodiments of the present application are not limited to this.

[0075] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode and a negative electrode. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are intercalated and released back and forth between the positive and negative electrodes.

[0076] In some embodiments, the electrode assembly further includes a separator, which is disposed between the positive electrode and the negative electrode to prevent a short circuit between the positive and negative electrodes while allowing active ions to pass through.

[0077] 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 layer disposed on at least one surface of the positive electrode current collector.

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

[0079] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, stainless steel, copper, aluminum, nickel, silver-treated aluminum, silver-treated stainless steel, carbon electrode, carbon, nickel or titanium 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 polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0080] As an example, the positive electrode active material layer includes a positive electrode active material. The positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523), LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211), LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi0.805Co0.15Al0.05O2) and at least one of their modified compounds.

[0081] In some embodiments, the positive electrode may be a carbon foam or a metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, or an alloy foam, among others. When the metal foam is used as the positive electrode, the surface of the metal foam may or may not be provided with a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled and / or deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0082] In some embodiments, the negative electrode may be a negative electrode sheet, which may include a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.

[0083] As an example, the negative electrode current collector may be a metal foil, a metal foam, a carbon foam, or a composite current collector. For example, as the metal foil, stainless steel, copper, aluminum, nickel, silver-surface-treated aluminum, silver-surface-treated stainless steel, a carbon electrode, carbon, nickel, or titanium may be used. The metal foam may be nickel foam, copper foam, aluminum foam, or an alloy foam. 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 (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0084] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0085] In some embodiments, the negative electrode may be made of carbon foam or metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, or alloy foam. When the metal foam is used as the negative electrode sheet, the surface of the metal foam may or may not be provided with a negative electrode active material.

[0086] As an example, the negative electrode current collector may be filled with or / and deposited with a lithium source material, potassium metal, or sodium metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0087] 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.

[0088] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode sheet and the negative electrode sheet.

[0089] 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.

[0090] As an example, the primary material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0091] 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.

[0092] 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.

[0093] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0094] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0095] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent can also be an ether solvent. Ether solvents can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0096] The gel electrolyte consists of a polymer-based electrolyte framework network, combined with an ionic liquid-lithium salt.

[0097] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0098] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, or the like.

[0099] As an example, the inorganic solid electrolyte can be an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0100] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0101] 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.

[0102] In some embodiments, the electrode assembly is a laminate structure.

[0103] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0104] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0105] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0106] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0107] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0108] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0109] 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.

[0110] 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.

[0111] As an example, the battery cells may be cylindrical, prismatic, soft-pack or other shaped battery cells. Prismatic battery cells include square-shell, blade-shaped, and polygonal batteries. Polygonal batteries may be, for example, hexagonal batteries.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0116] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0117] During the battery cell manufacturing process, the various plate structures on the battery cell are typically connected and fixed by welding to form the outer shell. During the welding process, weld holes are often formed at the weld locations, which reduces the strength of the plate structure at the corresponding weld holes. Consequently, during the use of the battery cell, the outer shell is prone to cracking and damage due to factors such as internal expansion or external stress, which is detrimental to the structural reliability of the battery cell.

[0118] Based on the above technical problems, the present application provides a battery cell, a battery, an electrical device and a method for preparing a battery cell, which reduces the risk of cracking of the battery cell and improves the service life and reliability of the battery cell by changing the welding method.

[0119] 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.

[0120] 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.

[0121] 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 provided inside the vehicle 1000. For example, the battery 100 can be provided 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, for example. The battery can be used for starting and navigating the vehicle 1000. Of course, the battery 100 can also be used to drive the vehicle 1000, replacing or partially replacing fuel or natural gas to provide drive for the vehicle 1000.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] FIG3 is a schematic structural diagram of the battery module 500 shown in FIG2 .

[0126] 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.

[0127] The structure of the battery cell 600 will now be described with reference to the accompanying drawings. Referring to Figures 4 and 5 , the battery cell 600 includes a housing 10 and an electrode assembly 20. Housing 10 defines a housing space and includes a first plate portion 111 and a second plate portion 121. The first and second plates 111, 121 are welded to form a molten pool structure 30, and weld holes H are located within the molten pool structure 30. The electrode assembly 20 is housed within the housing space. The thickness of the first plate portion 111 is greater than that of the second plate portion 121, and at least a portion of the weld holes H are located within the first plate portion 111.

[0128] The electrode assembly 20 is the primary component of the battery cell 600 for providing electrical energy. The housing 10 has a space for accommodating the electrode assembly 20. The shape of the housing 10 can be determined based on the shape of the electrode assembly 20. For example, if the electrode assembly 20 is cylindrical, the housing 10 can have a cylindrical outer shape. If the electrode assembly 20 is a rectangular parallelepiped structure, the housing 10 can have a rectangular outer shape.

[0129] The housing 10 includes a first plate portion 111 and a second plate portion 121, and the first plate portion 111 and the second plate portion 121 can be prepared and formed separately. The thickness of the first plate portion 111 is greater than the thickness of the second plate portion 121. Generally, the greater the thickness of a component, the greater its corresponding structural strength, and the lower the risk of the component being damaged by external force. Depending on the different arrangements between the first plate portion 111 and the second plate portion 112, the thickness direction of the first plate portion 111 can be consistent with the thickness direction of the second plate portion 112, or the thickness direction of the first plate portion 111 can also intersect with the thickness direction of the second plate portion 112.

[0130] Furthermore, the first plate portion 111 and the second plate portion 121 are typically welded together to form a molten pool structure 30, which includes portions of the first plate portion 111 and the second plate portion 121. During the welding process between the first and second plates 111 and 121, the high temperature causes the solubility of hydrogen in the molten metal droplets and molten metal to be very high. During the cooling process, as the temperature drops, the solubility of hydrogen decreases, and some hydrogen gas does not have enough time to float to the outside environment, resulting in the formation of weld pores H in the molten pool structure 30.

[0131] On this basis, the embodiment of the present application adjusts the welding process of the first plate portion 111 and the second plate portion 121 so that at least part of the welding pores H can be located within the first plate portion 111. Since the first plate portion 111 has a greater thickness than the second plate portion 121, the thickness of the first plate portion 111 itself can still ensure that it will not crack or break under the influence of certain stresses. Furthermore, since at least part of the welding pores H can be located within the first plate portion 111, the number of welding pores H located within the second plate portion 121 is reduced, thereby helping to reduce the impact of the welding pores H on the strength of the second plate portion 121, reducing the risk of cracking or breakage of the second plate portion 121, and helping to improve the reliability of the battery cell 600.

[0132] In some embodiments, the molten pool structure 30 includes a main body 31 and an end portion 32 connected to the main body 31 and extending into the first plate portion 111 . The main body 31 is exposed to the outer surface of the housing 10 , and at least part of the welding pores H are located in the end portion 32 .

[0133] During the welding process of the first plate portion 111 and the second plate portion 121, due to different welding methods, the corresponding molten pool structure 30 will also be different, wherein the molten pool structure 30 will include a main body portion 31 and an end portion 32. Combined with the accompanying drawings, compared with the end portion 32, the main body portion 31 is usually closer to the outer surface of the shell 10 and the main body portion 31 will be exposed to the outer surface of the shell 10, and the cross-sectional width of the main body portion 31 is usually greater than the cross-sectional width of the end portion 32.

[0134] Depending on the welding method, the main body portion 31 and the end portion 32 in the molten pool structure 30 can have various structural types, and the relative positional relationship between the main body portion 31 and the end portion 32 can have various forms. For example, the first plate portion 111 is located on one side of the electrode assembly 20 along the first direction X, and the end portion 32 can be located on one side of the main body portion 31 along the first direction X, or the end portion 32 is located on one side of the main body portion 31 along other directions intersecting the first direction X.

[0135] Compared with the main body 31, during the welding process, more welding pores H are more easily formed in the end portion 32. On this basis, the embodiment of the present application can control the end portion 32 within the first plate portion 111 by adjusting the position relationship of the end portion 32 relative to the outer shell 10, so that more welding pores H can be located in the first plate portion 111, thereby reducing the risk of cracking of the outer shell 10 due to the presence of welding pores H and improving the reliability of the battery cell 600.

[0136] In some embodiments, the second plate portion 121 includes a first surface 1211 facing the electrode assembly 20. In the thickness direction of the first plate portion 111, the minimum distance L1 between the welding hole H located in the end portion 32 and the first surface 1211 satisfies the following conditions: 0.1 mm ≤ L1 ≤ 5 mm. Alternatively, L1 is one of 0.1 mm, 0.5 mm, 1 mm, 2 mm, and 5 mm.

[0137] Due to the presence of the molten pool structure 30, the strength of other structures on the housing 10 near the molten pool structure 30 is relatively weak. Furthermore, the strength of other structures on the housing 10 around the end 32 is further reduced due to the presence of the weld pores H. In this case, if the end 32 is too close to the second plate portion 121, the second plate portion 121, due to its inherently low thickness, is prone to cracking and damage under stress, affecting the reliability of the battery cell 600.

[0138] In view of this, the embodiment of the present application limits the minimum distance L1 between the weld holes H in the end portion 32 and the first surface 1211, such that L1 is not less than 0.1 mm. The first surface 1211 is the surface of the second plate portion 121 that faces the electrode assembly 20, i.e., the first surface 1211 constitutes the inner surface of the outer shell 10. The minimum distance L1 between the weld holes H in the end portion 32 and the first surface 1211 can be the minimum distance between the center of at least one weld hole H located in the end portion 32 and the first surface 1211.

[0139] In the embodiment of the present application, by adjusting the welding method, the minimum distance L1 between the welding hole H in the end portion 32 and the first surface 1211 can be no less than 0.1 mm. This reduces the effect of the welding hole H located within the end portion 32 on the thickness of the second plate portion 121, reduces the risk of cracking and damage to the second plate portion 121 in the battery cell 600, and improves the structural reliability of the battery cell 600.

[0140] Furthermore, the embodiment of the present application also sets L1 to no more than 5 mm, thereby reducing excessive offset of the end portion 32 relative to the second plate portion 121, which causes excessive adverse effects on the central position of the first plate portion 111, thereby improving the structural reliability of the first plate portion 111, and helping to increase the service life of the battery cell 600.

[0141] It should be noted that in the embodiment of the present application, although the minimum distance L1 between the welding hole H in the end portion 32 and the first surface 1211 is not less than 0.1 mm, the end portion 32 in the molten pool structure 30 can be partially located in the second plate portion 121, or the end portion 32 can also be arranged in contact with the second plate portion 121, as long as the minimum distance between the center of at least one welding hole H located in the end portion 32 and the first surface 1211 is not less than 0.1 mm.

[0142] In some embodiments, referring to FIG. 6 to FIG. 9 , in the thickness direction of the second plate portion 121 , the end portion 32 is spaced apart from the second plate portion 121 .

[0143] In the embodiment of the present application, by adjusting the welding method, the end portion 32 and the second plate portion 121 can be spaced apart, thereby further reducing the impact of the welding pores H inside the end portion 32 on the second plate portion 121, further reducing the risk of cracking and damage to the second plate portion 121, and improving the structural reliability of the battery cell 600.

[0144] In some embodiments, as shown in FIG. 7 to FIG. 9 , the first plate portion 111 is located on one side of the electrode assembly 20 along a first direction X, and the end portion 32 is located on one side of the body portion 31 along a second direction Y, where the first direction X and the second direction Y intersect.

[0145] The first plate portion 111 and the electrode assembly 20 are arranged relative to each other in a first direction X, wherein the first direction X can be located in the thickness direction of the first plate portion 111. The end portion 32 is located on one side of the main body portion 31 along the second direction Y. The first direction X and the second direction Y can have various angles. For example, as shown in FIG7 , the first direction X can be perpendicular to the second direction Y, or as shown in FIG6 , the first direction X and the second direction Y intersect and are not perpendicular.

[0146] The positional relationship between the end portion 32 and the main body portion 31 is usually determined by the specific welding method. Specifically, if the laser is irradiated along the first direction X to one of the first plate portion 111 and the second plate portion 121, the corresponding main body portion 31 and the end portion 32 are usually arranged side by side in the first direction X; if the laser is irradiated along other directions intersecting with the first direction X to one of the first plate portion 111 and the second plate portion 121, the corresponding main body portion 31 and the end portion 32 are usually arranged side by side in the other directions intersecting with the first direction X.

[0147] In summary, the embodiment of the present application tilts the laser incident direction during welding relative to the thickness direction of the first plate portion 111 so that the end portion 32 can be located on one side of the main body portion 31 along the second direction Y. This helps to make the end portion 32 be set further away from the second plate portion 121, thereby reducing the impact of the welding pores H inside the end portion 32 on the second plate portion 121, further reducing the risk of cracking and damage to the second plate portion 121, and improving the structural reliability of the battery cell 600.

[0148] It should be noted that, depending on different actual situations, the second direction Y may be parallel to the thickness direction of the second plate portion 121 , or the second direction Y may intersect with the thickness direction of the second plate portion 121 .

[0149] In some embodiments, the first plate portion 111 has a center portion 1111 and an edge portion 1112 located on the periphery of the center portion 1111. The edge portion 1112 is welded to the second plate portion 121 to form a molten pool structure 30. In the thickness direction of the second plate portion 121, the end portion 32 protrudes relative to the main body portion 31 in a direction close to the center portion 1111.

[0150] The central portion 1111 is located at the center of the first plate portion 111, and the edge portion 1112 is located at the edge of the first plate portion 111. The edge portion 1112 is disposed around the outer periphery of the central portion 1111. The central portion 1111 and the edge portion 1112 can have various shapes. For example, the projection of the central portion 1111 in the first direction X can be a circular structure, while the projection of the edge portion 1112 in the first direction X can be a circular ring structure; or the projection of the central portion 1111 in the first direction X can be a square structure, while the projection of the edge portion 1112 in the first direction X can be a square ring structure.

[0151] Compared to the center portion 1111, the edge portion 1112 is located closer to the second plate portion 121, and the edge portion 1112 needs to be welded to the second plate portion 121, that is, the molten pool structure 30 is generally located within the edge portion 1112. On this basis, in the embodiment of the present application, the end portion 32 protrudes relative to the main body 31 in a direction closer to the center portion 1111, that is, the end portion 32 is located farther away from the second plate portion 121 than the main body 31. This helps to increase the distance between the end portion 32 and the second plate portion 121, thereby reducing the impact of the welding pores H inside the end portion 32 on the second plate portion 121, and improving the reliability of the housing 10 structure.

[0152] In some embodiments, the housing 10 includes a shell 12 and an end cover 11 . The shell 12 has an opening K at at least one end in the first direction X. The end cover 11 is used to cover the opening K. The end cover 11 includes a first plate portion 111 , and the shell 12 includes a second plate portion 121 .

[0153] The shell 12 and the end cover 11 are welded and fixed and are used together to form the outer shell 10. The shell 12 has a hollow structure including an opening K. The end cover 11 is used to cover the opening K, that is, along the first direction X, the projection of the end cover 11 is at least partially located within the projection of the opening K, wherein the first direction X can be the thickness direction of the end cover 11.

[0154] The end cap 11 includes a first plate portion 111, and the housing 12 includes a second plate portion 121. The two are welded together to form a molten pool structure 30 and welding holes H located within the molten pool structure 30. Typically, due to factors such as thickness, the thickness of the end cap 11 is generally greater than that of the housing 12. On this basis, the embodiments of the present application control the welding method so that at least a portion of the welding holes H can be located within the first plate portion 111, that is, at least a portion of the welding holes H can be located within the end cap 11 rather than within the housing 12. This reduces the impact of the welding holes H on the strength of the housing 12, reduces the risk of cracking and damage to the housing 12, and improves the reliability of the battery cell 600.

[0155] It should be noted that the housing 12 may include multiple side panels connected end to end, and the multiple side panels together enclose the opening K. On this basis, the second plate portion 121 can be one of the side panels of the housing 12 that needs to be welded to the end cover 12. Furthermore, the thickness direction of the second plate portion 121 corresponds to the thickness direction of the side panel.

[0156] In some embodiments, as shown in FIG. 4 to FIG. 6 , a recess A is provided on the inner surface of the housing 12 near the opening K. The end cover 11 is at least partially located in the recess A and is fixed to the side of the recess A by welding.

[0157] A recess A may be provided inside the shell 12 , which may be used to support the end cover 11 . Optionally, the size of the recess A in the first direction X is not smaller than the size of the end cover 11 in the first direction X, so that the end cover 11 may be completely embedded in the shell 12 .

[0158] The end cap 11 is welded and fixed to the side surface of the recess A, wherein the side surface of the recess A refers to the inner surface of the recess A perpendicular to the first direction X and close to the accommodating space. Furthermore, in order to weld and fix the end cap 11 to the side surface of the recess A, top welding needs to be adopted during welding. Specifically, the laser needs to be incident from the side of the end cap 11 away from the electrode assembly 20, and irradiated on the surface of at least one of the end cap 11 and the shell 12 in the first direction X, and then, under the action of the laser, part of the structure of the end cap 11 and at least part of the structure at the recess A are melted and welded into one.

[0159] On this basis, in order to reduce the impact of the welding pores H on the second plate portion 121, the incident angle of the laser incident on the shell 10 can be adjusted and improved, or the incident position of the laser incident on the shell 10 can be adjusted and improved, so that at least part of the welding pores H are located in the first plate portion 111, thereby reducing the risk of cracking and damage of the second plate portion 121 and improving the reliability of the shell 10.

[0160] Or in other embodiments, as shown in Figures 8 and 9, the end cover 11 includes an end cover 11 body and a protrusion 113 arranged around the circumference of the end cover 11 body. The end cover 11 body is arranged corresponding to the opening K, and the protrusion 113 is located on one side of the shell 12 along the first direction X and is welded and fixed to the shell 12.

[0161] The end cap 11 includes a main body of the end cap 11 and a protrusion 113 disposed around the main body of the end cap 11. As shown in the figure, the cross-sectional shape of the two can be T-shaped. The shape of the main body of the end cap 11 and the shape of the protrusion 113 can take various forms. For example, the projection of the main body of the end cap 11 in the first direction X is circular, and the projection of the protrusion 113 in the first direction X is a circular ring. Alternatively, the projection of the main body of the end cap 11 in the first direction X is square, and the projection of the protrusion 113 in the first direction X is a square ring.

[0162] The main body of the end cap 11 is disposed corresponding to the opening K, that is, the projection of the main body of the end cap 11 in the first direction X is located within the projection of the opening K in the first direction X. The protrusion 113 is located on one side of the housing 12 along the first direction X, that is, the projection of the protrusion 113 in the first direction X is at least partially located outside the projection of the opening K in the first direction X, and the projection of the protrusion 113 in the first direction X at least partially overlaps with the projection of the housing 12 in the first direction X.

[0163] The protrusion 113 is welded to the housing 12, wherein the protrusion 113 and the housing 12 can be welded to each other in the first direction X. Furthermore, to weld the protrusion 113 to the housing 12, side welding is required. Specifically, the laser light needs to be incident from the outer peripheral side of the housing 12 and irradiated on the outer peripheral side of the housing 12 or the side of the protrusion 113 away from the main body of the end cap 11. Then, under the action of laser melting, at least a portion of the structure of the protrusion 113 is fused to the housing 12 to form a single piece.

[0164] On this basis, due to the influence of the side welding angle and the incident position, the end 32 in the molten pool structure 30 formed by the side welding can penetrate into the first plate portion 111, so that at least part of the welding pores H can be located in the end 32, thereby reducing the risk of cracking and damage of the second plate portion 121 and improving the reliability of the shell 10.

[0165] In summary, the technical solution provided by the embodiments of the present application is applicable to various welding methods, such as top welding and side welding, making it adaptable to different types of housing 10 structures and providing great flexibility. Furthermore, by locally adjusting the welding method, at least a portion of the welding holes H can be relocated within the first plate portion 111, thereby improving the reliability of the battery cell 600.

[0166] In some embodiments, as shown in Figures 6 and 8, the molten pool structure 30 includes a weld print structure J exposed on the outer surface of the shell 10, the end cover 11 is accommodated in the opening K, and the weld print structure J is at least partially exposed on the upper surface of the end cover 11; and / or, a portion of the structure in the end cover 12 is overlapped with the shell 12 in the first direction X, and the weld print structure J is at least partially exposed on the outer surface of the shell 12.

[0167] The weld mark structure J is the structure where the molten pool structure 30 is exposed on the outer surface of the housing 10. Depending on the welding method, the resulting weld mark structure J will vary. Specifically, if the housing 12 and the end cap 11 are welded together using top welding, at least a portion of the weld mark structure J in the resulting molten pool structure 30 will be exposed on the upper surface of the end cap 11. That is, the weld mark structure J can be observed when the housing 10 is viewed from the side of the end cap 11 facing away from the electrode assembly 20 and along the first direction X. If the housing 12 and the end cap 11 are welded together using side welding, at least a portion of the resulting molten pool structure 30 will be exposed on the outer surface of the housing 12. That is, the weld mark structure J can be observed when the housing 10 is viewed from the outer surface of the housing 12.

[0168] In the embodiment of the present application, the weld mark structure J formed may vary depending on the welding method. On this basis, by adjusting and changing the welding method, at least part of the welding pores H can be located in the first plate portion 111, thereby reducing the risk of cracking and damage to the second plate portion 121, and having strong flexibility and reliability.

[0169] In a second aspect, an embodiment of the present application provides a battery, which includes the battery cell 600 in any of the aforementioned embodiments.

[0170] 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.

[0171] In a third aspect, an embodiment of the present application provides an electrical device, which includes the battery cell 600 in any of the aforementioned embodiments.

[0172] It should be noted that the electrical device 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 here in the embodiment of the present application.

[0173] In a fourth aspect, referring to FIG. 10 , an embodiment of the present application provides a method for preparing a battery cell 600 , the method comprising:

[0174] S100 : providing a first plate portion 111 and a second plate portion 121 .

[0175] In step S100, the first plate portion 111 and the second plate portion 121 are both used to form the housing 10, and the thickness of the first plate portion 111 is greater than the thickness of the second plate portion 121. Depending on the arrangement of the first plate portion 111 and the second plate portion 121, the thickness direction of the first plate portion 111 may be parallel to the thickness direction of the second plate portion 121, or the thickness direction of the first plate portion 111 may intersect with the thickness direction of the second plate portion 121.

[0176] S110 : Welding the first plate portion 111 and the second plate portion 121 by laser irradiation.

[0177] In step S120, the embodiment of the present application adjusts the welding process so that the molten pool structure 30 formed by welding can penetrate into the first plate portion 111, thereby allowing at least some of the welding pores H to be located within the first plate portion 111. Since the first plate portion 111 itself has a certain thickness, even if welding pores H exist within the first plate portion 111, the thickness of the first plate portion 111 itself can still ensure that it will not crack or break under the influence of certain stresses. Furthermore, since at least some of the welding pores H can be located within the first plate portion 111, the number of welding pores H located within the second plate portion 121 is reduced, thereby helping to reduce the impact of the welding pores H on the strength of the second plate portion 121, reducing the risk of cracking and breakage of the second plate portion 121, and helping to improve the reliability of the battery cell 600.

[0178] In some embodiments, the end cover 11 includes a first plate portion 111 , the housing 12 includes a second plate portion 121 , and at least one end of the housing 12 in the first direction X has an opening K. The end cover 12 is used to cover the opening K.

[0179] The end cap 11 and the housing 12 can be welded together to form the outer shell 10. The end cap 11 can have an opening K on at least one side in the first direction X, covering the opening K. The thickness of the end cap 11 is greater than that of the housing 12. The end cap 11 and the housing 12 can have various shapes and structures. For example, the housing 12 can be cylindrical, with the projection of the end cap 11 in the first direction X being circular; or the housing 12 can be a rectangular parallelepiped, with the projection of the end cap 11 in the first direction X being square.

[0180] In the embodiment of the present application, by adjusting the welding method, the molten pool structure 30 formed by welding can be able to penetrate into the end cover 11, so that at least part of the welding pores H can be located in the end cover 11, thereby reducing the number of welding pores H located in the shell 12, thereby helping to reduce the impact of the welding pores H on the strength of the shell 12, reducing the risk of cracking and damage to the shell 12, and helping to improve the reliability of the battery cell 600.

[0181] In some embodiments, as shown in FIG6 and FIG7 , in step S110 , a laser is irradiated onto a surface of at least one of the end cap 11 and the housing 12 in the first direction X. The laser incident angle intersects the first direction X; and / or the position where the laser is irradiated onto the surface of the end cap 11 is spaced apart from the inner surface of the housing 12 .

[0182] The laser is irradiated on the surface of at least one of the end cover 11 and the shell 12 in the first direction X, that is, the embodiment of the present application adopts the top welding method to weld the shell 12 and the end cover 11 to be fixed. The laser needs to be incident from the side of the end cover 11 away from the electrode assembly 20 and irradiated on the surface of at least one of the end cover 11 and the shell 12 in the first direction X. Then, under the action of the laser, part of the structure of the end cover 11 and at least part of the structure at the recess A are melted and welded into one.

[0183] On this basis, in order to allow at least a portion of the weld pores H to be located within the end cap 11, the embodiment of the present application further adjusts at least one of the laser incident position and incident angle for top welding. Specifically, by controlling the laser incident angle to intersect with the first direction X, the relative positions of the main body 31 and the end portion 32 of the molten pool structure 30 formed by laser welding will also intersect with the first direction X, thereby causing the end portion 32 to shift away from the housing 12. This allows the weld pores H located within the end portion 32 to be located within the end cap 11, reducing the adverse effects of the weld pores H on the housing 12 and improving the reliability of the battery cell 600.

[0184] Alternatively, in other embodiments, the laser incident position may be adjusted so that the position where the laser irradiates the surface of the end cap 11 is spaced apart from the inner surface of the housing 12. Specifically, the laser irradiates directly onto the side of the end cap 11 facing away from the electrode assembly 20, and the position where the laser irradiates the surface of the end cap 11 is spaced apart from the inner surface of the housing 12 in a direction perpendicular to the first direction X.

[0185] This design helps to allow more structures in the molten pool structure 30 to be located in the end cover 11 rather than in the shell 12, and the end 32 in the molten pool structure 30 can also penetrate into the interior of the end cover 11, so that more welding pores H can be located in the end cover 11, reducing the adverse effects of the welding pores H on the shell 12 and improving the reliability of the battery cell 600.

[0186] In summary, based on the top welding process, the embodiment of the present application adjusts the incident position of the top welding relative to the shell 12 and the end cover 11, and at least one of the incident angles, thereby helping to enable at least part of the welding pores H to be located inside the end cover 11, reducing the adverse effects of the welding pores H on the shell 12, and improving the reliability of the battery cell 600.

[0187] In some embodiments, as shown in Figures 8 and 9, in step S110, a laser is irradiated onto the outer surface of at least one of the housing 12 and the end cap 11 in a third direction Z, where the third direction Z intersects with the first direction X and is parallel to the thickness direction of the second plate portion 121. Optionally, the first direction X is perpendicular to the third direction Z.

[0188] The housing 12 may include multiple side panels connected end to end, which together enclose the opening K. On this basis, the second plate portion 121 may be one of the side panels of the housing 12 that needs to be welded to the end cap 12 . Furthermore, the thickness direction of the second plate portion 121 , i.e., the third direction Z, corresponds to the thickness direction of the side panel.

[0189] The laser is irradiated on the outer surface of at least one of the housing 12 and the end cap 11 in the third direction Z. That is, in the embodiment of the present application, the housing 12 and the end cap 11 are welded and fixed by side welding. The laser is incident from the outer peripheral side of the housing 12 and irradiated on the outer peripheral surface of the housing 12 or the outer peripheral surface of the end cap 11 in the third direction Z. Then, under the action of the laser melting, at least part of the structure of the end cap 11 is fused with the housing 12 to form a single body.

[0190] In the embodiment of the present application, side welding is used so that the end 32 of the molten pool structure 30 formed by welding can extend into the end cover 11, so that the welding pore H in the end 32 can be located inside the end cover 11, reducing the impact of the welding pore H on the shell 12 and improving the structural reliability of the battery cell 600.

[0191] It should be noted that, in the embodiment of the present application, the incident direction of the laser can be parallel to the third direction Z, or the incident direction of the laser can also intersect with the third direction Z. In addition, the end 32 in the molten pool structure 30 is located on one side of the main body 31 along the second direction Y. Depending on the laser incident angle, the second direction Y can be parallel to the third direction Z, or the second direction Y can also intersect with the third direction Z. For example, when the laser is irradiated along the third direction Z to the outer surface of at least one of the end cover 11 and the shell 12, the second direction Y can be parallel to the third direction Z. Further optionally, the first direction X, the second direction Y and the third direction Z can be located in the same plane.

[0192] In some embodiments, as shown in FIG8 , the thickness of the second plate portion 121 is T, the dimension of the molten pool structure 30 in the first direction X is H, and the angle between the laser irradiation angle and the first direction X is β, where β satisfies: 90°-arcsin(T / H)≤β≤90°+arcsin(T / H).

[0193] The second plate portion 121 is at least a partial structure in the shell 12 used for welding and fixing to the end cover 11, wherein the "thickness of the second plate portion 121" mentioned in the embodiment of the present application refers to: the maximum thickness of the second plate portion 121, wherein the thickness of the second plate portion 121 at different positions can remain the same, or the thickness of the second plate portion 121 at different positions can also be different.

[0194] Furthermore, in the embodiment of the present application, regardless of whether a welding method such as top welding or side welding is adopted, in order to allow the end portion 32 in the molten pool structure 30 to penetrate into the end cover 11, the laser irradiation angle needs to be limited. Among them, by setting the laser irradiation angle to intersect with the first direction X, and the angle β between the two is set to be not less than 90°-arcsin (T / H), the risk of excessive welding pores H in the shell 12 due to excessive structures in the molten pool structure 30 being located in the shell 12, thereby reducing the risk of cracking and damage. Furthermore, the embodiment of the present application also sets the angle β to be no greater than 90°-arcsin (T / H) to reduce the risk of the molten pool structure 30 penetrating into the center of the end cover 11, reduce the adverse effects of the molten pool structure 30 on the end cover 11, and improve the reliability of the battery cell 600.

[0195] In some embodiments, β satisfies: 7°≤β≤173°. Optionally, β is one of 7°, 45°, 90°, 150°, and 173°.

[0196] In the embodiment of the present application, by setting β to no less than 7°, the risk of excessive weld pores H in the housing 12, which could result in cracking and damage, is reduced due to excessive structures within the molten pool structure 30 being located within the housing 12. Furthermore, the embodiment of the present application also sets the angle β to no greater than 173° to reduce the risk of the molten pool structure 30 penetrating into the center of the end cap 11, thereby reducing the adverse effects of the molten pool structure 30 on the end cap 11 and improving the reliability of the battery cell 600.

[0197] According to some embodiments of the present application, referring to Figures 4 to 9 , a battery cell 600 includes a housing 10 and an electrode assembly 20. The housing 10 includes a shell 12 and an end cap 11. The shell 12 has an opening K at at least one end in a first direction X. The end cap 11 is used to cover the opening K. The end cap 11 includes a first plate portion 111, and the housing 12 includes a second plate portion 121. The thickness of the first plate portion 111 is greater than the thickness of the second plate portion 121. The first plate portion 111 and the second plate portion 121 are welded to form a molten pool structure 30 and welding pores H located within the molten pool structure 30. The electrode assembly 20 is accommodated in the accommodation space, and at least some of the welding pores H are located within the end cap 11.

[0198] The molten pool structure 30 includes a main body 31 and an end portion 32 connected to the main body 31 and extending into the first plate portion 111. At least a portion of the weld holes H are located in the end portion 32. The end portion 32 is located on one side of the main body 31 along the second direction Y, which intersects the first direction X. The first plate portion 111 includes a central portion 1111 and an edge portion 1112 located around the central portion 1111. The edge portion 1112 is welded to the second plate portion 121. In the thickness direction of the second plate portion 121, the end portion 32 protrudes relative to the main body 31 toward the central portion 1111.

[0199] A recess A is provided on the inner surface of the housing 12 near the opening K. The end cap 11 is at least partially located within the recess A and is welded to the side of the recess A. Alternatively, the end cap 11 includes an end cap body 112 and a protrusion 113 disposed around the periphery of the end cap body 112. The end cap body 112 is disposed corresponding to the opening K. The protrusion 113 is located on one side of the housing 12 along the first direction X and is welded to the housing 12.

[0200] The molten pool structure 30 includes a weld print structure J exposed on the outer surface of the shell 10, the end cover 11 is accommodated in the opening K, and the weld print structure J is at least partially exposed on the upper surface of the end cover 11; or, part of the structure in the top cover is overlapped with the shell 12 in the first direction X, and the weld print structure J is at least partially exposed on the outer surface of the shell 12.

[0201] 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 having an accommodation space, the housing including a first plate portion and a second plate portion, the first plate portion and the second plate portion being welded to form a molten pool structure, and welding pores located within the molten pool structure; an electrode assembly accommodated within the accommodation space; wherein, the thickness of the first plate portion is greater than the thickness of the second plate portion, and at least part of the welding pores are located within the first plate portion.

2. The battery cell according to claim 1, wherein, the molten pool structure includes a body portion and an end portion connected to the body portion and extending into the first plate portion, the body portion being exposed on the outer surface of the housing, and at least part of the welding pores are located within the end portion.

3. The battery cell according to claim 2, wherein, the second plate portion includes a first surface facing the electrode assembly, and in the thickness direction of the second plate portion, the minimum distance between the welding pores located within the end portion and the first surface is L1, and L1 satisfies: 0.1 mm ≤ L1 ≤ 5 mm.

4. The battery cell according to claim 3, wherein, in the thickness direction of the second plate portion, the end portion and the second plate portion are spaced apart.

5. The battery cell according to claim 4, wherein, the first plate portion is located on one side of the electrode assembly along a first direction, the end portion is located on one side of the body portion along a second direction, and the second direction intersects the first direction.

6. The battery cell according to claim 5, wherein, the first plate portion has a central portion and an edge portion located on the periphery of the central portion, and the edge portion is welded to the second plate portion to form the molten pool structure; in the thickness direction of the second plate portion, the end portion protrudes towards the central portion relative to the body portion.

7. The battery cell according to any one of claims 1 to 6, wherein, the housing includes a housing body and an end cap, at least one end of the housing body has an opening in a first direction, the end cap is used to cover the opening, the end cap includes the first plate portion, and the housing body includes the second plate portion.

8. The battery cell according to claim 7, wherein, a recess is provided at a position on the inner surface of the housing body and close to the opening, at least part of the end cap is located within the recess and is welded and fixed to the side surface of the recess; or, the end cap includes an end cap body and a protruding portion surrounding the periphery of the end cap body, the end cap body is disposed corresponding to the opening, and the protruding portion is located on one side of the housing body along the first direction and is welded and fixed to the housing body.

9. The battery cell according to claim 7 or 8, wherein, the molten pool structure includes a weld mark structure exposed on the outer surface of the housing, the end cap is received within the opening, and at least part of the weld mark structure is exposed on the upper surface of the end cap; or, a part of the structure of the end cap and the housing body overlap in the first direction, and at least part of the weld mark structure is exposed on the outer surface of the housing body.

10. A battery comprising the battery cell according to any one of claims 1 to 9.

11. An electrical device includes a battery cell as described in any one of claims 1 to 9, and the battery cell is used to provide electrical energy.

12. A method for preparing a battery cell, comprising: providing a first plate portion and a second plate portion, wherein the thickness of the first plate portion is greater than that of the second plate portion; welding the first plate portion and the second plate portion by laser irradiation to form a molten pool structure extending into the first plate portion, so that at least part of the welding pores are located within the first plate portion.

13. The preparation method according to claim 12, wherein, the end cap includes the first plate portion, the housing includes the second plate portion, at least one end of the housing has an opening in a first direction, and the end cap is used to cover the opening.

14. The preparation method according to claim 13, wherein, in the process of welding the first plate portion and the second plate portion by laser irradiation, the laser is irradiated on the surface of at least one of the end cap and the housing in the first direction; wherein the incident angle of the laser intersects with the first direction; and / or, the position where the laser is irradiated on the surface of the end cap is spaced from the inner surface of the housing.

15. The preparation method according to claim 14, wherein, in the process of welding the first plate portion and the second plate portion by laser irradiation, the laser is irradiated on the outer surface of at least one of the housing and the end cap in a third direction, the third direction intersects with the first direction and the third direction is parallel to the thickness direction of the second plate portion.

16. The preparation method according to claim 14 or 15, wherein, the thickness of the second plate portion is T, the size of the molten pool structure in the first direction is H, and the included angle between the laser irradiation angle and the first direction is β, and β satisfies: 90° - arcsin(T / H) ≤ β ≤ 90° + arcsin(T / H).

17. The preparation method according to claim 16, wherein, β satisfies: 7° ≤ β ≤ 173°.

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