Cylindrical battery monomer, battery device and power utilization device

Abstract

The utility model provides a cylindrical battery monomer, a battery device and a power utilization device. Each cylindrical battery monomer comprises a shell, an end cover and an electrode assembly; an opening is formed in at least one end of the shell along the axial direction of the cylindrical battery monomer, the shell is made of steel, and the outer diameter D of the shell is greater than or equal to 40mm; the end cover seals the opening, the end cover and the shell jointly define a containing space, and the end cover is made of steel; the electrode assembly is accommodated in the accommodating space; the end cover and the shell are welded to form a fusion part, the effective fusion depth of the fusion part is H, and H is larger than or equal to 0.15 mm and smaller than or equal to 0.9 mm. The effective fusion depth of the fusion part formed by welding the end cover and the shell is controlled within the range of 0.15 mm-0. 9mm, the welding strength of the end cover and the shell is improved, the risk of welding failure of the end cover and the shell is reduced, meanwhile, the welding difficulty of the end cover and the shell is reduced, the welding strength and the welding difficulty of the end cover and the shell are both considered, and the service life of the end cover and the shell is prolonged. And the service life of the cylindrical battery monomer is prolonged.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, in particular to a cylindrical battery monomer, a battery device and a power utilization device. BACKGROUND

[0002] Energy saving and emission reduction is the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their energy saving and environmental protection advantages. For electric vehicles, battery technology is an important factor for their development.

[0003] In the battery technology, the service life of the battery monomer is a problem that cannot be ignored. Therefore, how to improve the service life of the battery monomer is a technical problem that needs to be solved in the battery technology. CONTENT OF THE INVENTION

[0004] The application provides a cylindrical battery monomer, a battery device and a power utilization device, which can effectively improve the service life of the cylindrical battery monomer.

[0005] In a first aspect, the application provides a cylindrical battery monomer, which comprises a shell, an end cover and an electrode assembly; the shell is formed with an opening at least at one end in the axial direction of the cylindrical battery monomer, the material of the shell comprises steel, the outer diameter of the shell is D, and D is greater than or equal to 40 mm; the end cover closes the opening, and the end cover and the shell jointly define a receiving space; the electrode assembly is accommodated in the receiving space, and the material of the end cover comprises steel; wherein the end cover and the shell are welded to form a fusion portion, the effective fusion depth of the fusion portion is H, and 0.15 mm≤H≤0.9 mm.

[0006] For the cylindrical battery monomer whose material of the end cover and the material of the shell both comprise steel and the outer diameter of the shell is greater than or equal to 40 mm, the cylindrical battery monomer has the characteristics of large volume and large capacity. During use, the end cover is more likely to deform with the change of the internal pressure of the cylindrical battery monomer, which is easy to cause the welding failure of the end cover and the shell. However, the effective fusion depth of the fusion portion formed by welding the end cover and the shell is controlled within the range of 0.15 mm-0.9 mm, which increases the welding strength of the end cover and the shell, reduces the risk of welding failure of the end cover and the shell, and reduces the welding difficulty of the end cover and the shell. In this way, the welding strength and the welding difficulty of the end cover and the shell are balanced, and the service life of the cylindrical battery monomer is improved.

[0007] In some embodiments, 0.25 mm≤H≤0.5 mm. H≥0.25 mm further increases the effective fusion depth of the fusion portion, further increases the welding strength of the end cover and the shell; and H≤0.5 mm further reduces the welding difficulty of the end cover and the shell.

[0008] In some embodiments, the end cover is provided with a pressure relief groove, and the end cover is configured to be able to split along at least a portion of the pressure relief groove when the cylindrical battery cell is relieved of pressure. The provision of the pressure relief groove enables the end cover to have a pressure relief function, and when the internal pressure of the cylindrical battery cell reaches the burst pressure of the end cover, the end cover is able to split along at least a portion of the pressure relief groove, so that a local area of the end cover is opened to release the internal pressure of the cylindrical battery cell, thereby reducing the risk of fire or explosion of the cylindrical battery cell, and effectively improving the reliability of the cylindrical battery cell.

[0009] In some embodiments, the minimum residual thickness of the pressure relief groove is L1, and 0.067≤L1 / H≤0.67. For a cylindrical battery cell with an outer diameter of the shell greater than or equal to 40 mm, the internal space utilization rate is high, and when the cylindrical battery cell is in thermal runaway, as the internal pressure gradually increases, the end cover will eventually be partially opened to relieve pressure. Although the discharge of the cylindrical battery cell can be discharged from the partially opened area of the end cover, the internal pressure of the cylindrical battery cell can still continue to rise during the discharge of the discharge to the outside, which can easily cause the welding of the end cover and the shell to fail, resulting in separation of the end cover and the shell, and the phenomenon of explosion and spraying. However, L1 / H≤0.67 makes the pressure required for the separation of the end cover and the shell be relatively far from the burst pressure of the end cover, so that even if the internal pressure of the cylindrical battery cell continues to rise during the pressure relief of the cylindrical battery cell through the end cover, the end cover and the shell are not easily separated. And L1 / H≥0.067 can reduce the risk of fatigue cracking of the end cover at the position of the pressure relief groove during the normal life cycle.

[0010] In some embodiments, 0.12≤L1 / H≤0.48. L1 / H≥0.12 further reduces the risk of separation of the end cover and the shell during the pressure relief of the cylindrical battery cell through the end cover. L1 / H≤0.48 can further reduce the risk of fatigue cracking of the end cover at the position of the pressure relief groove during the normal life cycle.

[0011] In some embodiments, the minimum residual thickness of the pressure relief groove is L1, the wall thickness of the side wall of the shell is L2, and 0.07≤L1 / L2≤0.5. In this way, the risk of damage to the shell when the cylindrical battery cell is in thermal runaway can be effectively reduced.

[0012] In some embodiments, the minimum residual thickness of the pressure relief groove is L1, and 0.06mm≤L1≤0.2mm. For an end cover made of steel, L1≥0.06mm, the end cover has sufficient strength at the position of the pressure relief groove, reducing the risk of fatigue cracking of the end cover at the position of the pressure relief groove during the normal life cycle. L1≤0.2mm makes the burst pressure of the end cover not too large, so that the end cover can split along the pressure relief groove more timely when the cylindrical battery cell is in thermal runaway.

[0013] In some embodiments, the pressure relief groove is an annular groove, and the inner diameter of the pressure relief groove is d, 0.5≤d / D≤0.8. d / D≥0.5, so that the area of ​​the pressure relief region defined by the pressure relief groove is larger, and the end cover has a larger pressure relief area, so that the internal emissions of the cylindrical battery cell can be quickly discharged during thermal runaway, which can reduce the risk of separation of the end cover and the shell. d / D≤0.8, so that the pressure relief region defined by the pressure relief groove is not deformed too much during the normal life cycle as the internal pressure of the cylindrical battery cell changes, thereby reducing the impact of the deformation of the pressure relief region on the position of the end cover in the pressure relief groove and reducing the risk of fatigue cracking of the end cover in the pressure relief groove.

[0014] In some embodiments, the thickness of the end cap is L3, the thickness of the side wall of the housing is L2, and 0.3 ≤ L2 / L3 ≤ 1.2. L2 / L3 ≥ 0.3 ensures that the ratio of the thickness of the end cap to the thickness of the side wall of the housing is not too large. This reduces the material used for the end cap, thereby lowering the manufacturing cost of the end cap, provided that the thickness of the side wall of the housing meets the required usage. L2 / L3 ≤ 1.2 ensures that the ratio of the thickness of the end cap to the thickness of the side wall of the housing is not too large. This ensures that the end cap has sufficient strength and deformation resistance, provided that the thickness of the side wall of the housing meets the required usage.

[0015] In some embodiments, 0.6 ≤ L2 / L3 ≤ 1. For cylindrical battery cells, the end caps are more susceptible to deformation due to their location at the axial ends of the cylindrical battery cells. When 0.6 ≤ L2 / L3 ≤ 1, the thickness of the end caps is equal to the thickness of the sidewalls of the housing, or slightly greater than the thickness of the sidewalls of the housing, thereby improving the strength and deformation resistance of the end caps.

[0016] In some embodiments, 0.3mm≤L2≤0.6mm; and / or, 0.3mm≤L3≤1mm. For a shell made of steel, L2≥0.3mm, so that the shell has sufficient wall thickness, improves the strength of the shell, and meets the strength requirements of the shell. L2≤0.6mm, so that the wall thickness of the side wall of the shell is not too large, reducing the material used for the shell and reducing the manufacturing cost of the shell; when the outer diameter of the shell is constant, the internal space of the shell can be larger to provide a larger space for the electrode assembly, which is conducive to improving the volume energy density of the cylindrical battery cell. For an end cap made of steel, L3≥0.3mm, so that the end cap has sufficient thickness to meet the strength requirements of the end cap. L3≤1mm, so that the thickness of the end cap is not too large, reducing the material used for the end cap and reducing the manufacturing cost of the end cap.

[0017] In some embodiments, the end cap includes a body, a first protruding portion, and a rim portion; the body having a first surface axially facing the electrode assembly; the first protruding portion surrounding an outer edge of the body and protruding from the first surface, the first protruding portion at least partially inserted into the housing; and the rim portion surrounding an outer edge of the first protruding portion, abutting against an end of the housing having an opening, and being welded to the housing to form a fusion portion. The first protruding portion of the body being at least partially inserted into the housing allows for rapid positioning of the end cap and the housing, and reduces the space available for axial movement of the electrode assembly within the cylindrical battery cell. The rim portion of the body abuts against the end of the housing having an opening, thereby limiting movement of the end cap relative to the housing in a direction approaching the electrode assembly and facilitating welding of the rim portion to the housing. Furthermore, during welding of the rim portion to the housing, whether the welding is performed axially or radially of the cylindrical battery cell, the first protruding portion serves to block high-temperature materials generated during the welding process, thereby reducing the risk of high-temperature materials entering the containment space and damaging the electrode assembly.

[0018] In some embodiments, the end cap has a contact interface with the shell, and the contact interface includes a first interface extending from the fusion portion toward the receiving space, the first interface being connected to the surface of the fusion portion at a first position; along the axial direction, the first protrusion has a second surface facing the electrode assembly, and the minimum distance between the first position and the second surface is L4, 2≤L4 / H≤20. In the event of thermal runaway of the cylindrical battery cell, the smaller the L4 / H, the more likely the fusion portion will crack from the first position, causing the weld between the end cap and the shell to fail. However, when L4 / H≥2, the risk of weld failure between the end cap and the shell in the event of thermal runaway of the cylindrical battery cell can be effectively reduced, thereby reducing the risk of separation between the end cap and the shell. When L4 / H≤20, when the effective penetration depth of the fusion portion meets the use requirements, the minimum distance between the first position and the second surface is not too large, reducing the space occupied by the first protrusion, freeing up more space for the electrode assembly, and facilitating an increase in the volumetric energy density of the cylindrical battery cell.

[0019] In some embodiments, 2.5 ≤ L4 / H ≤ 10. L4 / H ≥ 2.5 can further reduce the risk of separation between the end cap and the housing during thermal runaway of the cylindrical battery cell. L4 / H ≤ 10 can further increase the volumetric energy density of the cylindrical battery cell.

[0020] In some embodiments, the cylindrical battery cell further includes a first current collecting member housed in the receiving space and axially disposed between the end cap and the electrode assembly. The electrode assembly includes a first tab, and the first current collecting member connects the first tab and the first protrusion. The first current collecting member effectively electrically connects the first tab and the first protrusion, thereby achieving electrical connection between the electrode assembly and the end cap.

[0021] In some embodiments, the first protrusion is welded to the first current collecting member, and a first groove is formed in an area corresponding to the first protrusion on the side of the end cap facing away from the electrode assembly. The first groove serves as a marker, allowing the end cap to be welded to the first current collecting member along the first groove to accurately weld the first protrusion to the first current collecting member, thereby improving welding accuracy. Furthermore, the first protrusion and the first current collecting member can be welded together using penetration welding from the outside of the end cap, achieving a stable connection between the first protrusion and the first current collecting member.

[0022] In some embodiments, the end cap has a contact interface with the shell, and the contact interface includes a first interface and a second interface separated by a fusion portion, the first interface extends from the fusion portion to the receiving space, and the second interface extends from the fusion portion to the outside of the cylindrical battery cell, the first interface is connected to the surface of the fusion portion at a first position, and the second interface is connected to the surface of the fusion portion at a second position, and the minimum distance between the first position and the second position is the effective fusion depth of the fusion portion.

[0023] In some embodiments, the surface of the fusion portion includes a third surface, which connects the outer surface of the end cover and the outer surface of the shell; the end cover has a contact interface with the shell, and the contact interface includes a first interface extending from the fusion portion to the receiving space, and the first interface is connected to the surface of the fusion portion at a first position, and the minimum distance between the first position and the third surface is the effective melting depth of the fusion portion.

[0024] In a second aspect, an embodiment of the present application provides a battery device, comprising the cylindrical battery cell provided by any embodiment of the first aspect.

[0025] In a third aspect, an embodiment of the present application provides an electrical device, comprising the cylindrical battery cell provided by any embodiment of the first aspect or the battery device provided by any embodiment of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 A schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0028] Figure 2 An exploded view of a battery device provided in some embodiments of the present application;

[0029] Figure 3An exploded view of a cylindrical battery cell provided for some embodiments of the present application;

[0030] Figure 4 A perspective view of a cylindrical battery cell provided for some embodiments of the present application; Figure 3

[0031] Figure 5 A partial view of a cylindrical battery cell provided for some embodiments of the present application;

[0032] Figure 6 A perspective view of a cylindrical battery cell provided for some embodiments of the present application; Figure 5

[0033] Figure 7 A perspective view of an end cap provided for some embodiments of the present application; Figure 5

[0034] A perspective view of an end cap provided for some embodiments of the present application; Figure 8 Figure 7

[0035] Figure 9 A perspective view of an end cap provided for some embodiments of the present application; Figure 6 Figure 9 A perspective view of an end cap provided for some embodiments of the present application;

[0036] Figure 10 A perspective view of a cylindrical battery cell provided for some embodiments of the present application;

[0037] Figure 11 Figure 10 A perspective view of a cylindrical battery cell provided for some embodiments of the present application;

[0038] Figure 12 A perspective view of a cylindrical battery cell provided for some embodiments of the present application; Figure 11 Figure 12 A perspective view of a cylindrical battery cell provided for some embodiments of the present application;

[0039] Figure 13 A perspective view of a cylindrical battery cell provided for some embodiments of the present application;

[0040] Figure 14 Figure 13 A perspective view of a cylindrical battery cell provided for some embodiments of the present application;

[0041] Figure 15 A perspective view of a cylindrical battery cell provided for some embodiments of the present application; Figure 14 Figure 15

[0042] ​​​​​​​​​​Icons: 1-shell; 11-shell; 111-side wall; 12-end cover; 121-pressure relief groove; 1211-weak part; 122-body; 1221-first surface; 1222-fourth surface; 123-first protrusion; 1231-second surface; 124-edge; 125-contact interface; 1251-first interface; 1251a-first position; 12511-first part; 12512-second part; 1252-second interface; 1252a-second position; 126-first Groove; 127-second groove; 128-second protrusion; 13-accommodation space; 14-fusion portion; 141-third surface; 2-electrode assembly; 21-first pole ear; 22-second pole ear; 3-electrode terminal; 4-first current collecting member; 5-second current collecting member; 10-cylindrical battery cell; 20-casing; 201-first casing; 202-second casing; 100-battery device; 200-controller; 300-motor; 1000-vehicle; U-first edge; V-second edge; Z-axial direction. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0044] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only 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 drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0045] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the 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.

[0046] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0047] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0048] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0049] The term "plurality" used in this application refers to two or more (including two).

[0050] 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.

[0051] Battery cells include but are not limited to 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.

[0052] 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, active ions (such as lithium ions) move back and forth between the positive and negative electrodes. A separator, placed between the positive and negative electrodes, reduces the risk of short circuits while allowing active ions to pass through.

[0053] 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.

[0054] 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.

[0055] As an example, the positive electrode current collector can employ a metal foil or a composite current collector. For example, as the metal foil, aluminum subjected to silver plating on the surface, stainless steel subjected to silver plating on the surface, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, or titanium, or the like can be employed. The composite current collector can include a high molecular material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, or the like) on a high molecular material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, or the like).

[0056] As an example, the positive electrode active material can include at least one of a lithium-containing phosphate, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material of a battery cell can also be used. These positive electrode active materials can be used alone only one or two or more can be used in combination. Among them, examples of the lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFeP04 (which can also be referred to simply as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnP04), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxide can include, but are not limited to, lithium cobalt oxide (such as LiCo02), lithium nickel oxide (such as LiNi02), lithium manganese oxide (such as LiMn02, LiMn204), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3Mn 1 / 3 O2 (which can also be referred to simply as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to simply as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be referred to simply as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be referred to simply as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be referred to simply as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and at least one of its modified compounds, etc.

[0057] In some embodiments, a positive electrode may utilize a metal foam. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or the like. When a metal foam is used as the positive electrode, the surface of the metal foam may or may not include a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled or / and deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0058] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0059] 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 with a silver-plated surface, stainless steel with a silver-plated surface, 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, etc. 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.).

[0060] 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.

[0061] 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.

[0062] 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 battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0063] 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.

[0064] In some embodiments, the separator is a separator membrane, which can be any known porous separator membrane with good chemical and mechanical stability.

[0065] As an example, the separator can be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. In the case of a multi-layer composite film, the materials of each layer can be the same or different. 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.

[0066] 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.

[0067] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel, or solid. Liquid electrolytes include an electrolyte salt and a solvent.

[0068] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0069] In some embodiments, the solvent may include 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 may also be an ether solvent. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0070] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0071] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0072] 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.

[0073] As an example, the inorganic solid electrolyte may include 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.

[0074] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0075] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0076] In some embodiments, the electrode assembly is a laminate structure.

[0077] 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.

[0078] As an example, multiple separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0079] 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.

[0080] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0081] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive electrode tab and a negative electrode tab.

[0082] In some embodiments, the battery cell may include a housing that encapsulates components such as the electrode assembly and the electrolyte. The battery cell may be a cylindrical battery cell.

[0083] The battery apparatus mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple battery cells, which are connected in series, parallel, or hybrid via a busbar.

[0084] In some embodiments, the battery cell assembly is typically formed by arranging a plurality of battery cells; as an example, the battery cell assembly can be a battery module, which is formed by arranging and fixing a plurality of battery cells into one independent module.

[0085] As an example, the battery module can be formed by bundling a plurality of battery cells with a cable tie.

[0086] In some embodiments, the battery device can be a battery pack, which can include a box and one or more battery cell assemblies, the battery cell assemblies being accommodated in the box.

[0087] As an example, the battery cell assembly can be a battery module, which can be accommodated in the box by fixing the battery module in the box.

[0088] As an example, the battery cell assembly can also be accommodated in the box by directly fixing a plurality of battery cells in the box.

[0089] As an example, the box can include a first box and a second box. The first box and the second box are buckled so that an enclosed space is formed inside the box to accommodate the battery cell assembly. Here, enclosed means covered or closed, which can be sealed or unsealed. The first box can be a top cover or a bottom plate.

[0090] As an example, the box can include a top cover, a frame and a bottom plate. The top cover and the bottom plate are respectively connected with the frame so that an enclosed space is formed inside the box to accommodate the battery cell assembly.

[0091] As an example, the box can be part of the chassis structure of a vehicle. For example, the top cover of the box can be at least part of the floor of the vehicle, or the frame of the box can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0092] In some embodiments, the battery device refers to an energy storage device, which includes a box, at least one side of which is provided with a door. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0093] For a cylindrical battery cell, the cylindrical battery cell typically includes a shell and an electrode assembly, the electrode assembly being accommodated in the shell. The shell can include a shell body and an end cover, the shell body having an opening, the opening being closed by the end cover after the electrode assembly is loaded into the shell body to form a receiving space inside the shell to accommodate the electrode assembly.

[0094] To achieve a stable connection between the end cap and the shell, the end cap can be welded to the shell. However, for cylindrical battery cells where both the end cap and the shell are made of steel and the outer diameter of the shell is greater than or equal to 40 mm, the cylindrical battery cell is large in size and capacity. During use, as the internal pressure of the cylindrical battery cell changes, the end cap is more likely to deform, which can easily lead to weld failure between the end cap and the shell, shortening the service life of the battery cell.

[0095] Based on the above considerations, in order to alleviate the problem of easy welding failure between the end cover and the shell, an embodiment of the present application provides a cylindrical battery cell, which includes a shell, an end cover and an electrode assembly; the shell is formed with an opening at at least one end along the axial direction of the cylindrical battery cell, the material of the shell includes steel, and the outer diameter of the shell is D, D ≥ 40 mm; the end cover closes the opening, and the end cover and the shell jointly define a receiving space, and the material of the end cover includes steel; the electrode assembly is accommodated in the receiving space; wherein, the end cover and the shell are welded to form a fusion portion, and the effective penetration depth of the fusion portion is H, 0.15 mm ≤ H ≤ 0.9 mm.

[0096] In such a cylindrical battery cell, the effective penetration depth of the fusion portion formed by welding the end cap and the shell is controlled within the range of 0.15mm-0.9mm, thereby increasing the welding strength between the end cap and the shell, reducing the risk of welding failure between the end cap and the shell, and reducing the difficulty of welding the end cap and the shell. This balances the welding strength and difficulty of the end cap and the shell, thereby increasing the service life of the cylindrical battery cell.

[0097] The technical solutions described in the embodiments of the present application are applicable to various electrical devices that use cylindrical battery cells and battery devices, such as mobile phones, portable devices, laptop computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft.

[0098] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0099] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application. A battery device 100 is disposed within vehicle 1000. Battery device 100 can be located at the bottom, front, or rear of vehicle 1000. Battery device 100 can be used to power vehicle 1000. For example, battery device 100 can serve as the operating power source of vehicle 1000.

[0100] The vehicle 1000 may further include a controller 200 and a motor 300 . The controller 200 is used to control the battery device 100 to supply power to the motor 300 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0101] In some embodiments of the present application, the battery device 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0102] Please refer to Figure 2 , Figure 2 The exploded view of the battery device 100 provided in some embodiments of the present application can include a cylindrical battery cell 10 and a case 20 , wherein the case 20 is used to accommodate the cylindrical battery cell 10 .

[0103] Among them, a closed space for accommodating the cylindrical battery cells 10 is formed inside the box body 20, and the box body 20 can adopt various structures. In some embodiments, the box body 20 may include a first box body 201 and a second box body 202, and the first box body 201 and the second box body 202 are buckled with each other. The first box body 201 and the second box body 202 can be of various shapes, such as a rectangular parallelepiped, a cylinder, etc. The first box body 201 can be a hollow structure with one side open, and the second box body 202 can also be a hollow structure with one side open. The open side of the second box body 202 is buckled with the open side of the first box body 201 to form a box body 20 with a closed space. The first box body 201 can also be a hollow structure with one side open, and the second box body 202 is a plate-like structure. The second box body 202 is buckled with the open side of the first box body 201 to form a box body 20 with a accommodating space.

[0104] In the battery device 100, there can be one or more cylindrical battery cells 10. If there are multiple cylindrical battery cells 10, the multiple cylindrical battery cells 10 can be connected in series, parallel, or in a hybrid connection. Hybrid connection refers to the multiple cylindrical battery cells 10 being connected both in series and in parallel. Multiple cylindrical battery cells 10 can be connected in series, parallel, or in a hybrid connection to form a battery module, which is then connected in series, parallel, or in a hybrid connection to form a whole and housed within the housing 20. Alternatively, all cylindrical battery cells 10 can be directly connected in series, parallel, or in a hybrid connection, and then the whole formed by all cylindrical battery cells 10 is housed within the housing 20.

[0105] In some embodiments, the battery device 100 may further include a busbar component, through which the multiple cylindrical battery cells 10 can be electrically connected to each other, thereby enabling series connection, parallel connection, or hybrid connection of the multiple cylindrical battery cells 10. The busbar component may be a metal conductor, such as copper, iron, aluminum, stainless steel, or an aluminum alloy.

[0106] Please refer to Figure 3 and Figure 4 , Figure 3 An exploded view of a cylindrical battery cell 10 provided in some embodiments of the present application;Figure 4 for Figure 3 The cylindrical battery cell 10 is shown in an isometric view. The cylindrical battery cell 10 may include a housing 1 and an electrode assembly 2 , wherein the electrode assembly 2 is accommodated in the housing 1 .

[0107] In some embodiments, the housing 1 may include a shell 11 and an end cap 12, wherein the shell 11 has an opening and the end cap 12 closes the opening of the shell 11. The closing here means covering or closing, which may be sealed or non-sealed.

[0108] The housing 11 is a component for accommodating the electrode assembly 2. The housing 11 is cylindrical and can be a hollow structure with an opening at one end or with openings at opposite ends. The electrode assembly 2 can be partially or completely located within the housing 11.

[0109] The end cap 12 and the housing 11 together define a receiving space 13 for accommodating the electrode assembly 2 and other components ( Figure 3 and Figure 4 The end cap 12 may be welded to the housing 11 to close the opening of the housing 11. The shape of the end cap 12 may be adapted to the shape of the housing 11, and the end cap 12 may be a circular plate structure adapted to the housing 11.

[0110] In an embodiment where the housing 11 is open at one end, one end cap 12 may be provided. In an embodiment where the housing 11 is open at two opposite ends, two end caps 12 may be provided. The two end caps 12 respectively close the two openings of the housing 11, and the two end caps 12 and the housing 11 together define a receiving space 13.

[0111] In some embodiments, the cylindrical battery cell 10 may further include an electrode terminal 3, which is disposed on the outer casing 1. The electrode terminal 3 is used to electrically connect to the tab of the electrode assembly 2 to input or output electrical energy from the cylindrical battery cell 10. The electrode terminal 3 may be disposed on the shell 11 of the outer casing 1 or on the end cap 12 of the outer casing 1. The electrode terminal 3 and the tab may be directly connected, for example, by welding the electrode terminal 3 to the tab. The electrode terminal 3 and the tab may also be indirectly connected, for example, by indirectly connecting the electrode terminal 3 to the tab via a current collecting member. The current collecting member may be a metal conductor, such as copper, iron, aluminum, steel, or an aluminum alloy.

[0112] As an example, Figure 3 and Figure 4As shown, the housing 11 has an opening at one end. There is only one end cap 12 in the housing 1, and each end cap 12 seals the opening of the housing 11. An electrode terminal 3 is provided at the end of the housing 11 opposite the end cap 12. A first electrode tab 21 and a second electrode tab 22 are formed at opposite ends of the electrode assembly 2. The first electrode tab 21 is electrically connected to the end cap 12 via a first current collecting member 4, and the second electrode tab 22 is electrically connected to the electrode terminal 3 via a second current collecting member 5. One of the first electrode tab 21 and the second electrode tab 22 is a positive electrode tab, and the other is a negative electrode tab.

[0113] Please refer to Figure 5 and Figure 6 , Figure 5 A partial view of a cylindrical battery cell 10 provided in some embodiments of the present application; Figure 6 for Figure 5 A partial enlarged view of point A in the middle. An embodiment of the present application provides a cylindrical battery cell 10, which includes a shell 11, an end cover 12, and an electrode assembly 2. The shell 11 is formed with an opening at at least one end along the axial direction Z of the cylindrical battery cell 10. The material of the shell 11 includes steel. The outer diameter of the shell 11 is D, and D ≥ 40 mm. The end cover 12 closes the opening. The end cover 12 and the shell 11 together define a receiving space 13. The electrode assembly 2 is accommodated in the receiving space 13. The material of the end cover 12 includes steel. The end cover 12 and the shell 11 are welded to form a fusion portion 14. The effective penetration depth of the fusion portion 14 is H, and 0.15 mm ≤ H ≤ 0.9 mm.

[0114] Along the axial direction Z of the cylindrical battery cell 10 , the shell 11 may have an opening at only one end, and one end cap 12 is provided accordingly; the shell 11 may also have openings at both opposite ends, and two end caps 12 are provided accordingly.

[0115] The housing 11 includes a sidewall 111 surrounding the outside of the electrode assembly 2. The cross-section of the sidewall 111 is annular and perpendicular to the axial direction Z of the cylindrical battery cell 10. In embodiments where the housing 11 is open at only one end, the housing 11 may further include a bottom wall disposed at the end of the sidewall 111 away from the end cap 12. The bottom wall and the sidewall 111 may be integrally formed. In embodiments where the housing 11 has openings at both opposing ends, the sidewall 111 constitutes the housing 11.

[0116] The material of the housing 11 includes steel. The housing 11 can be made of steel. The entire housing 11 can be made of steel, or a portion of the housing 11 can be made of steel. For example, the housing 11 includes a first substrate and a first protective layer disposed on the surface of the first substrate. The first substrate is made of steel, and the first protective layer is made of a non-steel material. The first protective layer can be an anti-oxidation layer, for example, a nickel layer plated on the surface of the second substrate.

[0117] The outer diameter of the housing 11 is the diameter of the outer circumference of the sidewall 111 of the housing 11. D can be any value among 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, etc., or a range between any two values.

[0118] The material of the end cap 12 includes steel. The end cap 12 can be made of steel. The end cap 12 can be made entirely of steel, or a portion of the end cap 12 can be made of steel. For example, the end cap 12 includes a second substrate and a second protective layer disposed on the surface of the second substrate, the second substrate being made of steel, and the second protective layer being made of a non-steel material. The second protective layer can be an anti-oxidation layer, for example, a nickel layer plated on the surface of the second substrate. Steel can include carbon steel, stainless steel, etc.

[0119] The electrode assembly 2 may be roughly cylindrical, and may be a wound structure or a laminated structure.

[0120] The fusion portion 14 is the portion where the end cap 12 and the shell 11 are fused together after welding. The fusion portion 14 may be a weld mark formed by welding the end cap 12 and the shell 11. The fusion portion 14 serves to connect the end cap 12 and the shell 11. The fusion portion 14 may be formed partially on the end cap 12 and partially on the shell 11. Welding the end cap 12 and the shell 11 may form a single fusion portion 14. For example, the fusion portion 14 may be an annular structure that extends circumferentially along the opening of the shell 11. The fusion portion 14 can achieve a sealed connection between the end cap 12 and the shell 11. Welding the end cap 12 and the shell 11 may also form multiple fusion portions 14, which are arranged circumferentially along the opening of the shell 11.

[0121] H can be any point value among 0.15mm, 0.18mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, etc., or a range value between any two of them.

[0122] For a cylindrical battery cell 10 in which both the end cap 12 and the shell 11 are made of steel and the outer diameter of the shell 11 is greater than or equal to 40 mm, the cylindrical battery cell 10 has the characteristics of large volume and large capacity. During use, as the internal pressure of the cylindrical battery cell 10 changes, the end cap 12 is more likely to deform, which can easily lead to failure of the welding between the end cap 12 and the shell 11.

[0123] In the embodiment of the present application, H ≥ 0.15 mm increases the weld strength between the end cap 12 and the housing 11 and reduces the risk of weld failure between the end cap 12 and the housing 11. H ≤ 0.9 mm reduces the difficulty of welding the end cap 12 and the housing 11. In other words, the effective penetration depth of the fusion portion 14 formed by welding the end cap 12 and the housing 11 is controlled within the range of 0.15 mm to 0.9 mm, taking into account both the weld strength and the weld difficulty between the end cap 12 and the housing 11, thereby increasing the service life of the cylindrical battery cell 10.

[0124] In some embodiments, 0.25 mm ≤ H ≤ 0.5 mm.

[0125] In this embodiment, H can take any point value among 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, 0.41mm, 0.42mm, 0.43mm, 0.44mm, 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.5mm, etc., or a range value between any two of them.

[0126] In this embodiment, H≥0.25 mm further increases the effective penetration depth of the fusion portion 14 and further increases the welding strength between the end cover 12 and the shell 11 ; H≤0.5 mm further reduces the welding difficulty between the end cover 12 and the shell 11 .

[0127] In some embodiments, please refer to Figure 7 and Figure 8 , Figure 7 for Figure 5 The structural diagram of the end cover 12 shown; Figure 8 for Figure 7 The end cap 12 is provided with a pressure relief groove 121 , and the end cap 12 is configured to be able to rupture along at least a portion of the pressure relief groove 121 when the cylindrical battery cell 10 is depressurized.

[0128] The pressure relief groove 121 can be a groove extending along a closed trajectory, which can be a circular trajectory, a rectangular trajectory, etc. The pressure relief groove 121 can also be a groove extending along a non-closed trajectory, which can be a C-shaped trajectory, a Y-shaped trajectory, a V-shaped trajectory, a U-shaped trajectory, etc. The pressure relief groove 121 can be formed on the end cap 12 by stamping, milling, laser etching, etc.

[0129] The end cap 12 forms a weak portion 1211 at the location where the pressure relief groove 121 is set. The weak portion 1211 can be the bottom wall of the pressure relief groove 121. The weak portion 1211 can be a uniform thickness structure or a non-uniform thickness structure. As an example, Figure 8 In the illustrated embodiment, the weak portion 1211 is a non-uniform thickness structure. The thickness of the weak portion 1211 gradually decreases from both ends to the middle along the width direction of the pressure relief groove 121 . The thickness direction of the weak portion 1211 is parallel to the axial direction Z of the cylindrical battery cell 10 .

[0130] It can be understood that when the end cover 12 is ruptured along at least a portion of the pressure relief groove 121 , the end cover 12 is ruptured from the weak portion 1211 .

[0131] A pressure relief groove 121 is provided on the end cap 12, so that the end cap 12 forms an integrated pressure relief mechanism, so that the end cap 12 has a pressure relief function. When the internal pressure of the cylindrical battery cell 10 reaches the bursting pressure of the end cap 12, the end cap 12 can be split along at least a portion of the pressure relief groove 121, so that a local area of ​​the end cap 12 is opened to release the internal pressure of the cylindrical battery cell 10, thereby reducing the risk of fire and explosion of the cylindrical battery cell 10, and thus effectively improving the reliability of the cylindrical battery cell 10.

[0132] In some embodiments, please refer to Figure 6 and Figure 8 The minimum residual thickness of the pressure relief groove 121 is L1, 0.067≤L1 / H≤0.67.

[0133] The minimum residual thickness of the pressure relief groove 121 is the minimum thickness of the weak portion 1211 , and the thickness at the thinnest position of the weak portion 1211 is the minimum thickness of the weak portion 1211 .

[0134] L1 / H can be any point value among 0.067, 0.08, 0.1, 0.12, 0.15, 0.17, 0.2, 0.22, 0.25, 0.27, 0.3, 0.32, 0.35, 0.37, 0.4, 0.42, 0.45, 0.48, 0.5, 0.52, 0.55, 0.57, 0.6, 0.62, 0.65, 0.67, etc., or any range between two of them.

[0135] For cylindrical battery cells 10 with an outer diameter of the shell 11 greater than or equal to 40 mm, the internal space utilization rate is very high. When the cylindrical battery cell 10 experiences thermal runaway, as its internal pressure gradually increases, the end cap 12 will eventually partially open to release pressure. Although the exhaust inside the cylindrical battery cell 10 can be discharged from the local area where the end cap 12 is opened, the internal pressure of the cylindrical battery cell 10 may continue to rise during the process of exhausting the exhaust, which may easily cause the welding between the end cap 12 and the shell 11 to fail, resulting in separation of the end cap 12 and the shell 11 and an explosion.

[0136] However, in this embodiment, L1 / H ≤ 0.67, which means that the pressure required to separate the end cap 12 from the housing 11 is significantly different from the burst pressure of the end cap 12. This prevents the end cap 12 from separating from the housing 11 even if the internal pressure continues to rise during the process of pressure relief through the end cap 12. Furthermore, L1 / H ≥ 0.067 can reduce the risk of fatigue cracking at the pressure relief groove 121 of the end cap 12 during its normal life cycle.

[0137] In some embodiments, 0.12≤L1 / H≤0.48.

[0138] L1 / H can be any one of 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, etc., or a range between any two of the values.

[0139] In this embodiment, L1 / H ≥ 0.12, further reducing the risk of separation between the end cap 12 and the housing 11 during pressure relief of the cylindrical battery cell 10 through the end cap 12. L1 / H ≤ 0.48 can further reduce the risk of fatigue cracking of the end cap 12 at the pressure relief groove 121 during its normal life cycle.

[0140] In some embodiments, please refer to Figure 6 and Figure 8 The minimum residual thickness of the pressure relief groove 121 is L1, the wall thickness of the side wall 111 of the shell 11 is L2, and 0.07≤L1 / L2≤0.5.

[0141] The sidewall 111 of the housing 11 may be of uniform thickness or non-uniform thickness. If the sidewall 111 of the housing 11 is of non-uniform thickness, the thickness of the sidewall 111 is the thickness at the thinnest position of the sidewall 111 .

[0142] L1 / L2 can be any point value among 0.07, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, etc., or a range of values ​​between any two of them.

[0143] In this embodiment, 0.07≤L1 / L2≤0.5, which can effectively reduce the risk of the housing 11 being damaged when the cylindrical battery cell 10 experiences thermal runaway.

[0144] In some embodiments, the minimum residual thickness of the pressure relief groove 121 is L1, 0.06 mm ≤ L1 ≤ 0.2 mm.

[0145] L1 can be any point value among 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, etc., or a range value between any two of them.

[0146] For end caps 12 made of steel, L1 ≥ 0.06 mm ensures sufficient strength at the pressure relief groove 121, reducing the risk of fatigue cracking at the pressure relief groove 121 during the normal lifecycle of the end cap 12. L1 ≤ 0.2 mm reduces the burst pressure of the end cap 12, allowing the end cap 12 to crack along the pressure relief groove 121 more promptly in the event of thermal runaway of the cylindrical battery cell 10.

[0147] In some embodiments, please refer to Figure 5 and Figure 7 The pressure relief groove 121 is an annular groove, and the inner diameter of the pressure relief groove 121 is d, 0.5≤d / D≤0.8.

[0148] The annular groove is a groove extending along a circular trajectory. The pressure relief groove 121 has a notch. It is understandable that the notch of the pressure relief groove 121 is annular, and the inner diameter of the notch of the pressure relief groove 121 is the inner diameter of the pressure relief groove 121 .

[0149] The pressure relief groove 121 defines a pressure relief area, and the weak portion 1211 is disposed around the pressure relief area. When the end cap 12 is ruptured along the pressure relief groove 121, the pressure relief area is opened, and the end cap 12 forms a pressure relief channel at the position corresponding to the pressure relief area, allowing the exhaust from the cylindrical battery cell 10 to be discharged through the pressure relief channel.

[0150] d / D can take any point value among 0.5, 0.52, 0.55, 0.58, 0.6, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, etc., or a range of values ​​between any two of them.

[0151] d / D ≥ 0.5, which increases the pressure relief area defined by the pressure relief groove 121. This provides the end cap 12 with a larger pressure relief area, allowing emissions from the cylindrical battery cell 10 to be quickly discharged during thermal runaway, thereby reducing the risk of separation between the end cap 12 and the housing 11. d / D ≤ 0.8, which prevents excessive deformation of the pressure relief area defined by the pressure relief groove 121 as the internal pressure of the cylindrical battery cell 10 changes over the normal lifecycle. This reduces the impact of deformation of the pressure relief area on the end cap 12 at the position of the pressure relief groove 121, and reduces the risk of fatigue cracking of the end cap 12 at the position of the pressure relief groove 121.

[0152] In some embodiments, please refer to Figure 6 The thickness of the end cover 12 is L3, the thickness of the side wall 111 of the shell 11 is L2, and 0.3≤L2 / L3≤1.2.

[0153] In the embodiment where the end cover 12 is provided with the pressure relief groove 121 , the thickness of the thinnest position in other regions of the end cover 12 except the weak portion 1211 is the thickness of the end cover 12 .

[0154] It can be understood that if 0.3≤L2 / L3<1, the thickness of the end cover 12 is greater than the wall thickness of the side wall 111 of the shell 11; if L2 / L3=1, the thickness of the end cover 12 is equal to the wall thickness of the side wall 111 of the shell 11; if 1<L2 / L3≤1.2, the thickness of the end cover 12 is less than the wall thickness of the side wall 111 of the shell 11.

[0155] L2 / L3 can take any point value among 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, etc., or any range value between two points.

[0156] L2 / L3 ≥ 0.3, which prevents the thickness ratio of the end cap 12 to the thickness of the side wall 111 of the housing 11 from being too large. When the thickness of the side wall 111 of the housing 11 meets the required usage, the material used for the end cap 12 is reduced, thereby lowering the manufacturing cost of the end cap 12. L2 / L3 ≤ 1.2, which prevents the thickness ratio of the end cap 12 to the thickness of the side wall 111 of the housing 11 from being too large. When the thickness of the side wall 111 of the housing 11 meets the required usage, the end cap 12 has sufficient strength and deformation resistance.

[0157] In some embodiments, 0.6≤L2 / L3≤1.

[0158] L2 / L3 can take any one of the point values 0.6, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 1 or a range value between any two of them.

[0159] For the cylindrical battery cell 10, since the end cover 12 is located at the end of the axial Z of the cylindrical battery cell 10, the end cover 12 is more easily deformed by force. And 0.6≤L2 / L3≤1 makes the thickness of the end cover 12 equal to the wall thickness of the side wall 111 of the shell 11, or the thickness of the end cover 12 slightly larger than the wall thickness of the side wall 111 of the shell 11, which improves the strength and deformation resistance of the end cover 12.

[0160] In some embodiments, 0.3mm≤L2≤0.6mm; and / or, 0.3mm≤L3≤1mm.

[0161] L2 can take any one of the point values 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.42mm, 0.45mm, 0.48mm, 0.5mm, 0.52mm, 0.55mm, 0.58mm, 0.6mm or a range value between any two of them.

[0162] L3 can take any one of the point values 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.42mm, 0.45mm, 0.48mm, 0.5mm, 0.52mm, 0.55mm, 0.58mm, 0.6mm, 0.62mm, 0.65mm, 0.68mm, 0.7mm, 0.72mm, 0.75mm, 0.78mm, 0.8mm, 0.82mm, 0.85mm, 0.88mm, 0.9mm, 0.92mm, 0.95mm, 0.98mm, 1mm or a range value between any two of them.

[0163] For the shell 11 made of steel, L2≥0.3 mm, so that the shell 11 has sufficient wall thickness, the strength of the shell 11 is improved, and the requirement of the shell 11 on the strength is met. L2≤0.6 mm, so that the wall thickness of the side wall 111 of the shell 11 is not too large, the material of the shell 11 is reduced, and the manufacturing cost of the shell 11 is reduced; in the case that the outer diameter of the shell 11 is constant, the internal space of the shell 11 can be larger, so as to provide a larger space for the electrode assembly 2, which is beneficial to improve the volumetric energy density of the cylindrical battery cell 10. For the end cover 12 made of steel, L3≥0.3 mm, so that the end cover 12 has sufficient thickness, and the requirement of the end cover 12 on the strength is met. L3≤1 mm, so that the thickness of the end cover 12 is not too large, the material of the end cover 12 is reduced, and the manufacturing cost of the end cover 12 is reduced. In addition, in the case that the end cover 12 is provided with the pressure relief groove 121, L3≤1 mm, which can reduce the forming difficulty of the pressure relief groove 121.

[0164] In some embodiments, please continue to refer to Figure 7 , the end cover 12 includes a body portion 122, a first protruding portion 123, and an edge portion 124. The body portion 122 has a first surface 1221 facing the electrode assembly 2 along the axial direction Z of the cylindrical battery cell 10. The first protruding portion 123 is arranged around the outer edge of the body portion 122 and protrudes from the first surface 1221, and the first protruding portion 123 is at least partially inserted into the shell 11. The edge portion 124 is arranged around the outer edge of the first protruding portion 123, and the edge portion 124 abuts the end of the shell 11 where the opening is formed, and the edge portion 124 is welded with the shell 11 to form the fusion portion 14.

[0165] As shown in Figure 7 , the body portion 122 and the first protruding portion 123 can be divided by a first edge U, which is the outer edge of the body portion 122. The edge portion 124 and the first protruding portion 123 can be divided by a second edge V, which is the outer edge of the first protruding portion 123. In Figure 7 , the first edge U and the second edge V are both shown by dashed lines.

[0166] The body portion 122 can be a circular structure, and the body portion 122 and the edge portion 124 can be annular structures.

[0167] The portion of the first protruding portion 123 inserted into the shell 11 can form a positioning fit with the shell 11, for example, the outer peripheral surface of the first protruding portion 123 and the inner peripheral surface of the side wall 111 of the shell 11 are in contact with each other.

[0168] The first protruding part 123 can be electrically connected with the electrode assembly 2. The first protruding part 123 can directly abut against the electrode assembly 2, for example, the first protruding part 123 is directly connected with the tab of the electrode assembly 2; the first protruding part 123 can also indirectly abut against the electrode assembly 2, for example, the first protruding part 123 is connected with the tab of the electrode assembly 2 through an intermediate piece, which can be a current collecting member.

[0169] As an example, the thickness of the body part 122 is equal to the thickness of the end cover 12, and the body part 122, the first protruding part 123 and the edge part 124 are integrally formed. The pressure relief groove 121 is arranged on the body part 122. The body part 122 has a fourth surface 1222 facing away from the electrode assembly 2 along the axial direction Z of the cylindrical battery monomer 10, and the minimum distance between the first surface 1221 and the fourth surface 1222 is equal to the thickness of the body part 122. The fourth surface 1222 is provided with a second groove 127, which is a circular groove, and the position corresponding to the second groove 127 on the first surface 1221 is provided with a second protruding part 128, which protrudes from the first surface 1221 along the axial direction Z of the cylindrical battery monomer 10. The size of the second protruding part 128 protruding from the first surface 1221 is smaller than that of the first protruding part 123, and the opening of the pressure relief groove 121 is formed on the surface of the second protruding part 128 facing away from the first surface 1221. The second groove 127 can provide an opening space for the pressure relief area of the end cover 12.

[0170] In the present embodiment, the first protruding part 123 of the body part 122 is at least partially inserted into the shell 11, which can realize the rapid positioning of the end cover 12 and the shell 11, and reduce the space for the electrode assembly 2 to move along the axial direction Z inside the cylindrical battery monomer 10. The edge part 124 of the body part 122 abuts against the end of the shell 11 having the opening, which can limit the movement of the end cover 12 relative to the shell 11 in the direction close to the electrode assembly 2, and facilitate the welding of the edge part 124 and the shell 11. In addition, during the welding of the edge part 124 and the shell 11, whether the welding is performed along the axial direction Z of the cylindrical battery monomer 10 or along the radial direction of the cylindrical battery monomer 10, the first protruding part 123 can block the high-temperature substances generated during the welding of the edge part 124 and the shell 11, thereby reducing the risk of damage to the electrode assembly 2 caused by the high-temperature substances entering the accommodation space 13.

[0171] In some embodiments, please refer to Figure 6 and Figure 9 , Figure 9 is Figure 6 the local enlarged view of B in FIG. Figure 9The end cap 12 has a contact interface 125 with the housing 11. This contact interface 125 includes a first interface 1251 extending from the fusion portion 14 toward the receiving space 13. The first interface 1251 is connected to the surface of the fusion portion 14 at a first position 1251a. Along the axial direction Z of the cylindrical battery cell 10, the first protrusion 123 has a second surface 1231 facing the electrode assembly 2. The minimum distance between the first position 1251a and the second surface 1231 is L4, where 2 ≤ L4 / H ≤ 20.

[0172] The contact interface 125 is the surface where the end cap 12 contacts the housing 11. In embodiments where the end cap 12 includes a body 122, a first protruding portion 123, and an edge portion 124, the contact interface 125 may be partially located on the edge portion 124 and partially located on the first protruding portion 123. In other words, both the edge portion 124 and the first protruding portion 123 contact the housing 11.

[0173] First interface 1251 is the portion of contact interface 125 that extends from fusion portion 14 toward receiving space 13. First interface 1251 may be a portion of contact interface 125, or it may be the entire contact interface 125. First interface 1251 may be located entirely within first protrusion 123, for example, the outer circumference of first protrusion 123 may constitute first interface 1251. Alternatively, first interface 1251 may be located partially within first protrusion 123, with the remainder located within edge portion 124.

[0174] As an example, in Figure 6 and Figure 9 In the illustrated embodiment, the contact interface 125 further includes a second interface 1252. The second interface 1252 is separated from the first interface 1251 by the fusion portion 14. The second interface 1252 extends from the fusion portion 14 toward the exterior of the cylindrical battery cell 10. The second interface 1252 is connected to the surface of the fusion portion 14 at a second location 1252a. The minimum distance between the first location 1251a and the second location 1252a is the effective penetration depth of the fusion portion 14. The first interface 1251 includes a first portion 12511 and a second portion 12512. The first portion 12511 is the outer circumferential surface of the first protrusion 123. Along the axial direction Z of the cylindrical battery cell 10, the edge portion 124 has an inner end surface facing the housing 11. The inner end surface of the edge portion 124 abuts against the end of the housing 11 where the opening is formed. A portion of the inner end surface of the edge portion 124 constitutes the second portion 12512 of the first interface 1251, while another portion of the inner end surface of the edge portion 124 constitutes the second interface 1252.

[0175] The second surface 1231 may be the surface of the end cap 12 closest to the electrode assembly 2 along the axial direction Z of the cylindrical battery cell 10 . The second surface 1231 may directly abut against the electrode assembly 2 or indirectly abut against the electrode assembly 2 through an intermediate piece.

[0176] L4 is the minimum distance between the first position 1251a and the second surface 1231 along the axial direction Z of the cylindrical battery cell 10. L4 / H can be any value among 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc., or a range between any two values.

[0177] When the cylindrical battery cell 10 experiences thermal runaway, the smaller the L4 / H, the more likely the fusion portion 14 is to crack starting from the first position 1251a, causing the weld between the end cap 12 and the shell 11 to fail. However, when L4 / H ≥ 2, the risk of weld failure between the end cap 12 and the shell 11 during thermal runaway of the cylindrical battery cell 10 can be effectively reduced, thereby reducing the risk of separation between the end cap 12 and the shell 11. When L4 / H ≤ 20, when the effective penetration depth of the fusion portion 14 meets the required usage, the minimum distance between the first position 1251a and the second surface 1231 is not excessively large, reducing the space occupied by the first protrusion 123, freeing up more space for the electrode assembly 2, and facilitating an increase in the volumetric energy density of the cylindrical battery cell 10.

[0178] In some embodiments, 2.5≤L4 / H≤10.

[0179] In this embodiment, L4 / H can take any point value among 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, etc., or a range value between any two of them.

[0180] When L4 / H≥2.5, the risk of separation between the end cap 12 and the housing 11 during thermal runaway of the cylindrical battery cell 10 can be further reduced. When L4 / H≤10, the volume energy density of the cylindrical battery cell 10 can be further increased.

[0181] In some embodiments, please refer to Figure 6 The cylindrical battery cell 10 also includes a first current collecting member 4, which is accommodated in the accommodating space 13. Along the axial direction Z of the cylindrical battery cell 10, the first current collecting member 4 is arranged between the end cover 12 and the electrode assembly 2. The electrode assembly 2 has a first electrode tab 21. The first current collecting member 4 connects the first electrode tab 21 and the first protrusion 123.

[0182] The first current collecting member 4 may be a metal conductor and may be in a disc shape. The first current collecting member 4 may also be called a current collecting disc.

[0183] The first electrode tab 21 can be a positive electrode tab or a negative electrode tab.

[0184] The first current collecting member 4 connects the first electrode tab 21 and the first protrusion 123, electrically connecting the electrode assembly 2 to the end cap 12. Along the axial direction Z of the cylindrical battery cell 10, the second surface 1231 of the first protrusion 123 abuts the current collecting member, which in turn abuts the first electrode tab 21. The first current collecting member 4 and the first electrode tab 21 can be connected by welding, bonding, or other methods; the first current collecting member 4 and the first protrusion 123 can also be connected by welding, bonding, or other methods.

[0185] In this embodiment, the first current collecting member 4 can effectively realize the electrical connection between the first electrode tab 21 and the first protrusion 123 , thereby realizing the electrical connection between the electrode assembly 2 and the end cover 12 .

[0186] In some embodiments, please refer to Figure 6 The first protrusion 123 is welded to the first current collecting member 4 , and a first groove 126 is formed in an area corresponding to the first protrusion 123 on a side of the end cover 12 facing away from the electrode assembly 2 .

[0187] As an example, the first groove 126 is an annular groove.

[0188] When forming the end cap 12, a first groove 126 can be punched out of the plate to form the corresponding first protrusion 123, thereby reducing the difficulty of forming the first protrusion 123. The thickness of the plate is the thickness of the end cap 12.

[0189] First groove 126 serves as a marker. When welding end cap 12 to first current collecting member 4, welding can be performed along first groove 126 to accurately weld first protrusion 123 to first current collecting member 4, improving welding accuracy. Furthermore, first protrusion 123 and first current collecting member 4 can be welded together through penetration welding from the outside of end cap 12, achieving a stable connection between first protrusion 123 and first current collecting member 4.

[0190] In some embodiments, please refer to Figures 10-12 , Figure 10 Partial views of cylindrical battery cells 10 provided in some other embodiments of the present application; Figure 11 for Figure 10 A partial enlarged view of point E in the middle; Figure 12 for Figure 11 The local enlarged view of F in ( Figure 12The end cap 12 has a contact interface 125 that contacts the housing 11. The contact interface 125 includes a first interface 1251 and a second interface 1252 separated by the fusion portion 14. The first interface 1251 extends from the fusion portion 14 toward the receiving space 13, and the second interface 1252 extends from the fusion portion 14 toward the exterior of the cylindrical battery cell 10. The first interface 1251 is connected to the surface of the fusion portion 14 at a first position 1251a, and the second interface 1252 is connected to the surface of the fusion portion 14 at a second position 1252a. The minimum distance between the first position 1251a and the second position 1252a is the effective penetration depth of the fusion portion 14.

[0191] As an example, the outer circumference of the first protrusion 123 is the first interface 1251, and the inner end surface of the edge portion 124 is the second interface 1252, which is connected to the outer circumference of the edge portion 124. It can be understood that a portion of the surface of the fusion portion 14 connects the first interface 1251 and the second interface 1252.

[0192] As an example, the fusion portion 14 is an annular structure. The location where the first interface 1251 connects with the surface of the fusion portion 14 forms a first circle, and the location where the second interface 1252 connects with the surface of the fusion portion 14 forms a second circle. The diameter of the second circle is greater than the diameter of the first circle. The minimum distance between the first and second circles is the minimum distance between the first location 1251a and the second location 1252a. The cross-section of the fusion portion 14 in the radial direction of the cylindrical battery cell 10 gradually decreases along the direction from the end cap 12 to the electrode assembly 2. The cross-section of the fusion portion 14 is parallel to the radial direction of the cylindrical battery cell 10.

[0193] In some embodiments, please refer to Figures 13-15 , Figure 13 A partial view of a cylindrical battery cell 10 provided in some other embodiments of the present application; Figure 14 for Figure 13 A partial enlarged view of point G in the middle; Figure 15 for Figure 14 The local enlarged view of I in ( Figure 15 The surface of the fusion portion 14 includes a third surface 141, which connects the outer surface of the end cap 12 with the outer surface of the housing 11. The end cap 12 has a contact interface 125 with the housing 11. The contact interface 125 includes a first interface 1251 extending from the fusion portion 14 toward the receiving space 13. The first interface 1251 is connected to the surface of the fusion portion 14 at a first position 1251a. The minimum distance between the first position 1251a and the third surface 141 is the effective penetration depth of the fusion portion 14.

[0194] The third surface 141 is a portion of the surface of the fusion portion 14 that connects the outer surface of the end cover 12 and the outer surface of the shell 11. Figure 14and Figure 15 The portion of the end cap 12 exposed to the outside of the cylindrical battery cell 10 is the outer surface of the end cap 12 , and the portion of the housing 11 exposed to the outside of the cylindrical battery cell 10 is the outer surface of the housing 11 .

[0195] The first interface 1251 may be entirely located on the first protruding portion 123 , for example, the outer peripheral surface of the first protruding portion 123 is the first interface 1251 ; the first interface 1251 may also be partially located on the first protruding portion 123 and partially located on the edge portion 124 .

[0196] As an example, in Figure 14 and Figure 15 In the illustrated embodiment, the edge portion 124 of the end cap 12 may have an inner end surface and an outer end surface, which are arranged opposite each other along the axial direction Z of the cylindrical battery cell 10. The inner end surface of the edge portion 124 abuts against the end of the housing 11 where the opening is formed. The outer end surface of the edge portion 124 constitutes the outer surface of the end cap 12, and the outer circumferential surface of the side wall 111 of the housing 11 constitutes the outer surface of the housing 11. The third surface 141 connects the outer circumferential surface of the side wall 111 of the housing 11 and the outer end surface of the edge portion 124 of the end cap 12. The first interface 1251 includes a first portion 12511, which is the outer circumferential surface of the first protrusion 123, and a second portion 12512, which is the inner end surface of the edge portion 124. The outer circumferential surface of the first protrusion 123 is connected to the inner end surface of the edge portion 124.

[0197] As an example, the fusion portion 14 is an annular structure, the first interface 1251 and the surface of the fusion portion 14 are connected to form a first circle, the third surface 141 is a rotational surface, and the minimum distance between the first circle and the third surface 141 is the minimum distance between the first position 1251a and the third surface 141. The cross-section of the fusion portion 14 in the axial direction Z of the cylindrical battery cell 10 gradually decreases along the direction from the edge portion 124 to the main body portion 122, and the cross-section of the fusion portion 14 is parallel to the radial direction of the cylindrical battery cell 10. Figure 14 and 15 In the illustrated embodiment, the distance between the first position 1251 a and the third surface 141 within the plane where the second portion 12512 is located is equal to the minimum distance between the first position 1251 a and the third surface 141 .

[0198] An embodiment of the present application provides a battery device 100 , including the cylindrical battery cell 10 provided in any one of the above embodiments.

[0199] An embodiment of the present application provides an electrical device, including the cylindrical battery cell 10 provided by any one of the above embodiments or the battery device 100 provided by any one of the above embodiments.

[0200] The present invention also provides a cylindrical battery cell 10, comprising a housing 11, an end cap 12, an electrode assembly 2, an electrode terminal 3, a first current collecting member 4, and a second current collecting member 5. The housing 11 has an outer diameter D, D ≥ 40 mm, and is made of steel. The housing 11 has an opening at only one end along the axial direction Z of the cylindrical battery cell 10. The end cap 12 seals the opening of the housing 11, and together with the housing 11, the end cap 12 defines a receiving space 13. The end cap 12 is made of steel. The electrode assembly 2, the first current collecting member 4, and the second current collecting member 5 are accommodated in the receiving space 13. Along the axial direction Z of the cylindrical battery cell 10, a first electrode tab 21 and a second electrode tab 22 are formed at opposite ends of the electrode assembly 2, respectively. The first electrode tab 21 is electrically connected to the end cap 12 via the first current collecting member 4, and the second electrode tab 22 is electrically connected to the electrode terminal 3 via the second current collecting member 5. The electrode terminal 3 is disposed at the end of the housing 11 opposite the end cap 12.

[0201] The end cap 12 includes a body portion 122, a first protruding portion 123, and an edge portion 124. The body portion 122 has a first surface 1221 that faces the electrode assembly 2 along the axial direction Z of the cylindrical battery cell 10. The first protruding portion 123 is disposed around the outer edge of the body portion 122 and protrudes from the first surface 1221. The first protruding portion 123 is at least partially inserted into the housing 11 and abuts against the electrode assembly 2 through the first current collecting member 4. Along the axial direction Z of the cylindrical battery cell 10, the first protruding portion 123 has a second surface 1231 that faces the electrode assembly 2. The second surface 1231 abuts against the first current collecting member 4. The edge portion 124 is disposed around the outer edge of the first protruding portion 123. The edge portion 124 abuts against one end of the housing 11 where the opening is formed. The edge portion 124 is welded to the housing 11 to form a fusion portion 14. The main body 122 is provided with a pressure relief groove 121 , which is an annular groove. The end cap 12 is configured to be able to split along at least a portion of the pressure relief groove 121 when the cylindrical battery cell 10 is depressurized.

[0202] The end cap 12 has a contact interface 125 in contact with the shell 11, and the contact interface 125 includes a first interface 1251 and a second interface 1252. The first interface 1251 and the second interface 1252 are separated by the fusion portion 14. The first interface 1251 extends from the fusion portion 14 to the receiving space 13, and the second interface 1252 extends from the fusion portion 14 to the outside of the cylindrical battery cell 10. The first interface 1251 is connected to the surface of the fusion portion 14 at a first position 1251a, and the second interface 1252 is connected to the surface of the fusion portion 14 at a second position 1252a. The minimum distance between the first position 1251a and the second position 1252a is the effective fusion depth of the fusion portion 14.

[0203] Among them, the minimum residual thickness of the pressure relief groove 121 is L1, the wall thickness of the side wall 111 of the shell 11 is L2, the thickness of the end cover 12 is L3, the minimum distance between the first position 1251a and the second surface 1231 is L4, the effective penetration depth of the fusion portion 14 is H, the inner diameter of the pressure relief groove 121 is d, 0.12≤L1 / H≤0.48, 0.07≤L1 / L2≤0.5, 0.6≤L2 / L3≤1; 2.5≤L4 / H≤10, 0.5≤d / D≤0.8, 0.25mm≤H≤0.5mm, 0.06mm≤L1≤0.2mm, 0.3mm≤L2≤0.6mm, 0.3mm≤L3≤1mm.

[0204] The present invention also provides a cylindrical battery cell 10, comprising a housing 11, an end cap 12, an electrode assembly 2, an electrode terminal 3, a first current collecting member 4, and a second current collecting member 5. The housing 11 has an outer diameter D, D ≥ 40 mm, and is made of steel. The housing 11 has an opening at only one end along the axial direction Z of the cylindrical battery cell 10. The end cap 12 seals the opening of the housing 11, and together with the housing 11, the end cap 12 defines a receiving space 13. The end cap 12 is made of steel. The electrode assembly 2, the first current collecting member 4, and the second current collecting member 5 are accommodated in the receiving space 13. Along the axial direction Z of the cylindrical battery cell 10, a first electrode tab 21 and a second electrode tab 22 are formed at opposite ends of the electrode assembly 2, respectively. The first electrode tab 21 is electrically connected to the end cap 12 via the first current collecting member 4, and the second electrode tab 22 is electrically connected to the electrode terminal 3 via the second current collecting member 5. The electrode terminal 3 is disposed at the end of the housing 11 opposite the end cap 12.

[0205] The end cap 12 includes a body portion 122, a first protruding portion 123, and an edge portion 124. The body portion 122 has a first surface 1221 that faces the electrode assembly 2 along the axial direction Z of the cylindrical battery cell 10. The first protruding portion 123 is disposed around the outer edge of the body portion 122 and protrudes from the first surface 1221. The first protruding portion 123 is at least partially inserted into the housing 11 and abuts against the electrode assembly 2 through the first current collecting member 4. Along the axial direction Z of the cylindrical battery cell 10, the first protruding portion 123 has a second surface 1231 that faces the electrode assembly 2. The second surface 1231 abuts against the first current collecting member 4. The edge portion 124 is disposed around the outer edge of the first protruding portion 123. The edge portion 124 abuts against one end of the housing 11 where the opening is formed. The edge portion 124 is welded to the housing 11 to form a fusion portion 14. The main body 122 is provided with a pressure relief groove 121 , which is an annular groove. The end cap 12 is configured to be able to split along at least a portion of the pressure relief groove 121 when the cylindrical battery cell 10 is depressurized.

[0206] The surface of the fusion portion 14 includes a third surface 141, which connects the outer surface of the end cover 12 and the outer surface of the shell 11. The end cover 12 has a contact interface 125 in contact with the shell 11. The contact interface 125 includes a first interface 1251 extending from the fusion portion 14 to the accommodating space 13. The first interface 1251 is connected to the surface of the fusion portion 14 at a first position 1251a. The minimum distance between the first position 1251a and the third surface 141 is the effective fusion depth of the fusion portion 14.

[0207] Among them, the minimum residual thickness of the pressure relief groove 121 is L1, the wall thickness of the side wall 111 of the shell 11 is L2, the thickness of the end cover 12 is L3, the minimum distance between the first position 1251a and the second surface 1231 is L4, the effective penetration depth of the fusion portion 14 is H, the inner diameter of the pressure relief groove 121 is d, 0.12≤L1 / H≤0.48, 0.07≤L1 / L2≤0.5, 0.6≤L2 / L3≤1; 2.5≤L4 / H≤10, 0.5≤d / D≤0.8, 0.25mm≤H≤0.5mm, 0.06mm≤L1≤0.2mm, 0.3mm≤L2≤0.6mm, 0.3mm≤L3≤1mm.

[0208] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0209] The above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit this application. Those skilled in the art will appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application are intended to be within the scope of protection of this application.

Claims

1. A cylindrical battery cell, characterized in that: include: A shell having an opening formed at at least one end along the axial direction of the cylindrical battery cell, the shell being made of steel and having an outer diameter D of 40 mm or greater; an end cover, closing the opening, the end cover and the shell together defining a receiving space, the material of the end cover including steel; an electrode assembly, accommodated in the receiving space; The end cover and the shell are welded to form a fusion portion, and the effective penetration depth of the fusion portion is H, 0.15mm≤H≤0.9mm.

2. The cylindrical battery cell according to claim 1, wherein: 0.25mm≤H≤0.5mm.

3. The cylindrical battery cell according to claim 1, wherein: The end cover is provided with a pressure relief groove, and the end cover is configured to be able to be broken along at least a portion of the pressure relief groove when the cylindrical battery cell is depressurized.

4. The cylindrical battery cell according to claim 3, wherein: The minimum residual thickness of the pressure relief groove is L1, 0.067≤L1 / H≤0.

67.

5. The cylindrical battery cell according to claim 4, wherein: 0.12≤L1 / H≤0.

48.

6. The cylindrical battery cell according to claim 3, wherein: The minimum residual thickness of the pressure relief groove is L1, the wall thickness of the side wall of the shell is L2, and 0.07≤L1 / L2≤0.

5.

7. The cylindrical battery cell according to claim 3, wherein: The minimum residual thickness of the pressure relief groove is L1, 0.06mm≤L1≤0.2mm.

8. The cylindrical battery cell according to claim 3, wherein: The pressure relief groove is an annular groove, and the inner diameter of the pressure relief groove is d, 0.5≤d / D≤0.

8.

9. The cylindrical battery cell according to any one of claims 1 to 8, characterized in that: The thickness of the end cover is L3, the thickness of the side wall of the shell is L2, and 0.3≤L2 / L3≤1.

2.

10. The cylindrical battery cell according to claim 9, wherein: 0.6≤L2 / L3≤1.

11. The cylindrical battery cell according to claim 9, wherein: 0.3mm≤L2≤0.6mm; and / or, 0.3mm≤L3≤1mm.

12. The cylindrical battery cell according to any one of claims 1 to 8, characterized in that: The end cap comprises: a body portion having a first surface facing the electrode assembly along the axial direction; a first protrusion, disposed around an outer edge of the main body and protruding from the first surface, wherein the first protrusion is at least partially inserted into the shell; The edge portion is arranged around the outer edge of the first protruding portion, the edge portion is pressed against one end of the shell where the opening is formed, and the edge portion and the shell are welded to form the fusion portion.

13. The cylindrical battery cell according to claim 12, wherein: The end cover has a contact interface with the housing, the contact interface including a first interface extending from the fusion portion toward the receiving space, the first interface being connected to a surface of the fusion portion at a first position; Along the axial direction, the first protrusion has a second surface facing the electrode assembly, and the minimum distance between the first position and the second surface is L4, 2≤L4 / H≤20.

14. The cylindrical battery cell according to claim 13, wherein: 2.5≤L4 / H≤10.

15. The cylindrical battery cell according to claim 12, wherein: The cylindrical battery cell further includes a first current collecting member, which is accommodated in the receiving space. Along the axial direction, the first current collecting member is arranged between the end cover and the electrode assembly. The electrode assembly has a first electrode tab, and the first current collecting member connects the first electrode tab and the first protrusion.

16. The cylindrical battery cell according to claim 15, wherein: The first protrusion is welded to the first current collecting member, and a first groove is formed in an area of ​​the end cover corresponding to the first protrusion on a side facing away from the electrode assembly.

17. The cylindrical battery cell according to any one of claims 1 to 8, characterized in that: The end cap has a contact interface with the shell, and the contact interface includes a first interface and a second interface separated by the fusion portion, the first interface extends from the fusion portion to the receiving space, and the second interface extends from the fusion portion to the outside of the cylindrical battery cell, the first interface is connected to the surface of the fusion portion at a first position, and the second interface is connected to the surface of the fusion portion at a second position, and the minimum distance between the first position and the second position is the effective fusion depth of the fusion portion.

18. The cylindrical battery cell according to any one of claims 1 to 8, characterized in that: The surface of the fusion portion includes a third surface, and the third surface connects the outer surface of the end cover and the outer surface of the shell; The end cover has a contact interface with the shell, and the contact interface includes a first interface extending from the fusion portion to the receiving space, the first interface is connected to the surface of the fusion portion at a first position, and the minimum distance between the first position and the third surface is the effective fusion depth of the fusion portion.

19. A battery device, characterized in that: The invention comprises a cylindrical battery cell according to any one of claims 1 to 18.

20. An electrical device, characterized in that: The invention comprises the cylindrical battery cell according to any one of claims 1 to 18 or the battery device according to claim 19.

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