Cylindrical battery cell, battery device and electric device

Abstract

The present application provides a cylindrical battery cell, a battery device and an electric device. The cylindrical battery cell comprises a casing, an end cover, and an electrode assembly; at least one end of the casing along the axial direction of the cylindrical battery cell is provided with an opening, the material of the casing comprises steel, the outer diameter of the casing is D, and D is greater than or equal to 40 mm; the end cover seals the opening, the end cover and the casing together define a receiving space, and the material of the end cover comprises steel; the electrode assembly is received in the receiving space; and the end cover and the casing are welded to form a weld portion, the effective weld penetration depth of the weld portion is H, and H is greater than or equal to 0.15 mm and less than or equal to 0.9 mm. The effective weld penetration depth of the weld portion formed by welding the end cover and the casing is controlled within the range of 0.15 mm to 0.9 mm, thereby increasing the welding strength between the end cover and the casing, reducing the risk of welding failure between the end cover and the casing, and lowering the welding difficulty between the end cover and the casing. In this way, both the welding strength and the welding difficulty between the end cover and the casing are taken into account, prolonging the service life of the cylindrical battery cell.

Description

Cylindrical battery cell, battery device and electric device Cross-reference to Related Applications

[0001] This application claims priority to Chinese Patent Application No. 2024223819914, filed on September 29, 2024, entitled “Cylindrical battery cell, battery device and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery, in particular, relates to a cylindrical battery cell, a battery device and an electric device. BACKGROUND

[0003] 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.

[0004] In the battery technology, the service life of the battery cell is a problem that cannot be ignored. Therefore, how to improve the service life of the battery cell is a technical problem that needs to be solved in the battery technology. SUMMARY

[0005] The embodiments of the present application provide a cylindrical battery cell, a battery device and an electric device, which can effectively improve the service life of the cylindrical battery cell.

[0006] In a first aspect, the embodiments of the present application provide a cylindrical battery cell, comprising a shell, an end cover and an electrode assembly; the shell is formed with an opening at least at one end of the cylindrical battery cell in the axial direction, 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.

[0007] For the cylindrical battery cell 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 cell has the characteristics of large volume and large capacity. During use, as the internal pressure of the cylindrical battery cell changes, the end cover is more likely to deform, which can easily lead to welding failure of the end cover and the shell. However, by controlling the effective fusion depth of the fusion portion formed by welding the end cover and the shell within the range of 0.15 mm-0.9 mm, the welding strength of the end cover and the shell is increased, the risk of welding failure of the end cover and the shell is reduced, and the welding difficulty of the end cover and the shell is reduced. In this way, the welding strength and welding difficulty of the end cover and the shell are balanced, and the service life of the cylindrical battery cell is improved.

[0008] In some embodiments, 0.25mm≤H≤0.5mm. H≥0.25mm further increases the effective penetration of the fusion, further increasing the welding strength of the end cover and the shell; H≤0.5mm further reduces the welding difficulty of the end cover and the shell.

[0009] In some embodiments, the end cover is provided with a pressure relief groove, and the end cover is configured to be split along at least part 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 can be split along at least part 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 and explosion of the cylindrical battery cell, and effectively improving the reliability of the cylindrical battery cell.

[0010] In some embodiments, the minimum residual thickness of the pressure relief groove is L1, and 0.067≤L1 / H≤0.67. For cylindrical battery cells with an outer diameter of the shell greater than or equal to 40mm, the internal space utilization 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 large 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 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 pressure relief groove position during the normal life cycle.

[0011] 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 pressure relief groove position during the normal life cycle.

[0012] 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.

[0013] In some embodiments, the minimum residual thickness of the pressure relief groove is L1, 0.06mm≤L1≤0.2mm. For the 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, so that the burst pressure of the end cover is not too large, and the end cover can be more timely cracked along the pressure relief groove when the cylindrical battery cell is in thermal runaway.

[0014] 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 pressure relief area defined by the pressure relief groove is larger, and the end cover has a larger pressure relief area, so that the internal discharge of the cylindrical battery cell can be quickly discharged when the cylindrical battery cell is in thermal runaway, and the risk of separation of the end cover from the shell can be reduced. d / D≤0.8, so that the deformation of the pressure relief area defined by the pressure relief groove is not too large with the change of the internal pressure of the cylindrical battery cell during the normal life cycle, reducing the influence of the deformation of the pressure relief area on the end cover at the position of the pressure relief groove, and reducing the risk of fatigue cracking of the end cover at the position of the pressure relief groove.

[0015] In some embodiments, the thickness of the end cover is L3, the wall thickness of the side wall of the shell is L2, and 0.3≤L2 / L3≤1.2. L2 / L3≥0.3, so that the ratio of the thickness of the end cover to the wall thickness of the side wall of the shell is not too large, and the shell side wall thickness meets the use requirements, reducing the use of the end cover, and reducing the manufacturing cost of the end cover. L2 / L3≤1.2, so that the ratio of the thickness of the end cover to the wall thickness of the side wall of the shell is not too large, and the shell side wall thickness meets the use requirements, and the end cover has sufficient strength and deformation resistance.

[0016] In some embodiments, 0.6≤L2 / L3≤1. For the cylindrical battery cell, the end cover is located at the axial end of the cylindrical battery cell, so that the end cover is more easily deformed under stress. And 0.6≤L2 / L3≤1, so that the thickness of the end cover is equal to or slightly larger than the wall thickness of the side wall of the shell, improving the strength and deformation resistance of the end cover.

[0017] In some embodiments, 0.3mm≤L2≤0.6mm; and / or, 0.3mm≤L3≤1mm. For the shell made of steel, L2≥0.3mm, so that the shell has sufficient wall thickness, improving the strength of the shell to meet the requirements of the shell on strength. L2≤0.6mm, so that the wall thickness of the side wall of the shell is not too large, reducing the material of the shell, reducing the manufacturing cost of the shell; in the case of a certain outer diameter of the shell, the internal space of the shell can be larger, to provide more space for the electrode assembly, which is conducive to improving the volumetric energy density of the cylindrical battery monomer. For the end cover made of steel, L3≥0.3mm, so that the end cover has sufficient thickness to meet the requirements of the end cover on strength. L3≤1mm, so that the thickness of the end cover is not too large, reducing the material of the end cover, reducing the manufacturing cost of the end cover.

[0018] In some embodiments, the end cover comprises a body portion, a first protruding portion, and an edge portion; the body portion has a first surface facing the electrode assembly in the axial direction; the first protruding portion is arranged around the outer edge of the body portion and protrudes from the first surface, and the first protruding portion is at least partially inserted into the shell; the edge portion is arranged around the outer edge of the first protruding portion, and the edge portion abuts the end of the shell where the opening is formed, and the edge portion and the shell are welded to form a fusion portion. The first protruding portion of the body portion is at least partially inserted into the shell, which can realize the rapid positioning of the end cover and the shell, and reduce the space for the electrode assembly to move axially inside the cylindrical battery monomer. The edge portion of the body portion abuts the end of the shell where the opening is formed, which can limit the movement of the end cover relative to the shell in the direction close to the electrode assembly, and facilitate the welding of the edge portion and the shell. In addition, during the welding of the edge portion and the shell, whether the edge portion and the shell are welded in the axial direction of the cylindrical battery monomer or in the radial direction of the cylindrical battery monomer, the first protruding portion can block the high-temperature substances generated during the welding of the edge portion and the shell, reducing the risk of damage to the electrode assembly caused by the high-temperature substances entering the accommodation space.

[0019] In some embodiments, the end cover has a contact interface in contact with the shell, the contact interface includes a first interface extending from the fusion portion to the accommodation space, the first interface is connected to the first position on the surface of the fusion portion; the first protruding portion has a second surface facing the electrode assembly in the axial direction, the minimum distance between the first position and the second surface is L4, 2≤L4 / H≤20. When the cylindrical battery cell is in thermal runaway, the smaller L4 / H is, the easier the fusion portion is to crack from the first position, resulting in welding failure of the end cover and the shell. However, L4 / H≥2 can effectively reduce the risk of welding failure of the end cover and the shell when the cylindrical battery cell is in thermal runaway, thereby reducing the risk of separation of the end cover and the shell. L4 / H≤20, in the case that the effective fusion depth of the fusion portion meets the use requirement, the minimum distance between the first position and the second surface is not too large, reducing the space occupation of the first protruding portion, so as to provide more space for the electrode assembly, which is beneficial to improve the volumetric energy density of the cylindrical battery cell.

[0020] In some embodiments, 2.5≤L4 / H≤10. L4 / H≥2.5 can further reduce the risk of separation of the end cover and the shell when the cylindrical battery cell is in thermal runaway. L4 / H≤10 can further improve the volumetric energy density of the cylindrical battery cell.

[0021] In some embodiments, the cylindrical battery cell further includes a first current collecting member, the first current collecting member is accommodated in the accommodation space, and the first current collecting member is arranged between the end cover and the electrode assembly in the axial direction. The electrode assembly has a first tab, and the first current collecting member connects the first tab and the first protruding portion. The first current collecting member can effectively realize the electrical connection between the first tab and the first protruding portion, and further realize the electrical connection between the electrode assembly and the end cover.

[0022] In some embodiments, the first protruding portion is welded with the first current collecting member, and a first groove is formed in a region corresponding to the first protruding portion on a side of the end cover away from the electrode assembly. The first groove can serve as an identification function. When welding the end cover and the first current collecting member, the first protruding portion and the first current collecting member can be welded along the first groove to accurately weld the first protruding portion and the first current collecting member, thereby improving the accuracy of welding. In addition, the first protruding portion and the first current collecting member can be welded together by means of penetration welding from the outside of the end cover, thereby realizing the stable connection of the first protruding portion and the first current collecting member.

[0023] In some embodiments, the end cover has a contact interface in contact with the shell, 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 accommodation space, the second interface extends from the fusion portion to the outside of the cylindrical battery cell, the first interface is connected to the first position on the surface of the fusion portion, the second interface is connected to the second position on the surface of the fusion portion, and the minimum distance between the first position and the second position is the effective fusion depth of the fusion portion.

[0024] In some embodiments, the surface of the fusion portion includes a third surface connecting the outer surface of the end cap and the outer surface of the shell; the end cap has a contact interface in contact with the shell, the contact interface includes a first interface extending from the fusion portion to the accommodation space, the first interface is connected to the surface of the fusion portion at a first position, the minimum distance between the first position and the third surface is the effective fusion depth of the fusion portion.

[0025] In a second aspect, the embodiments of the present application provide a battery device, including the cylindrical battery cell provided by any one of the embodiments of the first aspect.

[0026] In a third aspect, the embodiments of the present application provide a power consumption device, including the cylindrical battery cell provided by any one of the embodiments of the first aspect or the battery device provided by any one of the embodiments of the second aspect. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0028] FIG. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application;

[0029] FIG. 2 is an exploded view of a battery device provided by some embodiments of the present application;

[0030] FIG. 3 is an exploded view of a cylindrical battery cell provided by some embodiments of the present application;

[0031] FIG. 4 is an axonometric view of the cylindrical battery cell shown in FIG. 3;

[0032] FIG. 5 is a partial view of a cylindrical battery cell provided by some embodiments of the present application;

[0033] FIG. 6 is a partial enlarged view of A in FIG. 5;

[0034] FIG. 7 is a structural schematic diagram of an end cap shown in FIG. 5;

[0035] FIG. 8 is a partial enlarged view of C in FIG. 7;

[0036] FIG. 9 is a partial enlarged view of B in FIG. 6 (the shell is removed in FIG. 9);

[0037] FIG. 10 is a partial view of a cylindrical battery cell provided by some other embodiments of the present application;

[0038] FIG. 11 is a partial enlarged view of E in FIG. 10;

[0039] Fig. 12 is a partial enlarged view at F in Fig. 11 (the housing is removed in Fig. 12);

[0040] Fig. 13 is a partial view of a cylindrical battery cell according to yet other embodiments of the present application;

[0041] Fig. 14 is a partial enlarged view at G in Fig. 13;

[0042] Fig. 15 is a partial enlarged view at I in Fig. 14 (the housing is removed in Fig. 15).

[0043] Fig. 13 is a partial view of a cylindrical battery cell according to yet other embodiments of the present application; DETAILED DESCRIPTION

[0044] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of them. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0045] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments of the present application, and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover not exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, and are not intended to describe a particular order or a primary and secondary relationship.

[0046] Reference to "an embodiment" or "the embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all referring to a common embodiment, or an embodiment that is independent of all other embodiments.

[0047] In the description of the application, it is necessary to explain that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "attachment" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0048] In this application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in this application generally represents that the front and rear associated objects have an "or" relationship.

[0049] In the embodiments of the application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length and width of various components in the embodiments of the application shown in the drawings, as well as the overall thickness, length and width of the integrated device, are only exemplary and should not constitute any limitation on the application.

[0050] "Multiple" appearing in this application means two or more (including two).

[0051] In the embodiments of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to use.

[0052] The battery cell includes but is not limited to lithium ion battery, sodium ion battery, sodium lithium ion battery, lithium metal battery, sodium metal battery, lithium sulfur battery, magnesium ion battery, nickel hydrogen battery, nickel cadmium battery, lead-acid battery, etc.

[0053] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the battery cell, active ions (such as lithium ions) are inserted and extracted between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, which can reduce the risk of short circuit of the positive and negative electrodes, and at the same time allow the active ions to pass through.

[0054] In some embodiments, the positive electrode can be a positive electrode tab, and the positive electrode tab can include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0055] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode active material is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0056] 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, 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).

[0057] 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. As an example of the lithium-containing phosphate, at least one of lithium iron phosphate (such as LiFeP04(also referred to 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 can be included, but is not limited thereto. As an example of the lithium transition metal oxide, 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 / 3 Mn 1 / 3 O2(also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to as NCM622 LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM 811 LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof.

[0058] In some embodiments, the positive electrode can employ a foam metal. The foam metal can be a foam nickel, a foam copper, a foam aluminum, a foam alloy, etc. When the foam metal is used as the positive electrode, the foam metal surface can not be provided with the positive electrode active material, or of course can be provided with the positive electrode active material. As an example, the foam metal can also be filled or / and deposited with a lithium source material, a potassium metal or a sodium metal, the lithium source material being a lithium metal and / or a lithium-rich material.

[0059] In some embodiments, the negative electrode can be a negative electrode tab, which can include a negative electrode current collector.

[0060] As an example, the negative electrode current collector can employ a metal foil, a foam metal or a composite current collector. For example, as the metal foil, an aluminum with a silver plating surface treatment, a stainless steel with a silver plating surface treatment, a stainless steel, a copper, an aluminum, a nickel or a titanium, etc. can be employed. The foam metal can be a foam nickel, a foam copper, a foam aluminum, a foam alloy, 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 base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0061] As an example, the negative electrode tab can include the negative electrode current collector and the negative electrode active material provided on at least one surface of the negative electrode current collector.

[0062] As an example, the negative electrode current collector has two opposite surfaces in the thickness direction thereof, and the negative electrode active material is provided on any one or both of the two opposite surfaces of the negative electrode current collector.

[0063] As an example, the negative active material can employ a negative active material for a battery cell known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material for a battery cell can also be used. These negative active materials can be used alone or in combination of two or more.

[0064] In some embodiments, the material of the positive current collector can be aluminum, and the material of the negative current collector can be copper.

[0065] In some embodiments, the separator is a separator film. The separator film can be any porous structure separator film known in the art that has good chemical stability and mechanical stability.

[0066] As an example, the material of the separator film can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different. The separator can be a separate component located between the positive and negative electrodes, or can be attached to the surface of the positive and negative electrodes.

[0067] In some embodiments, the separator is a solid-state electrolyte. The solid-state electrolyte is disposed between the positive and negative electrodes, and functions to transport ions and separate the positive and negative electrodes.

[0068] In some embodiments, the battery cell further includes an electrolyte that functions to conduct ions between the positive and negative electrodes. The electrolyte can be in a liquid state, a gel state, or a solid state. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[0069] In some embodiments, the electrolyte salt can include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoroboric oxalate, lithium boric oxalate, lithium difluorophosphoric boric oxalate, and lithium tetrafluorophosphoric boric oxalate.

[0070] In some embodiments, the solvent can include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl 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, butyl sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be selected from ether solvents. The ether solvents can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0071] In some embodiments, the gel electrolyte includes a polymer as a backbone network of the electrolyte, and an ionic liquid-lithium salt.

[0072] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0073] As an example, the polymer solid electrolyte can be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single-ion polymer, a polyionic liquid-lithium salt, cellulose, or the like.

[0074] As an example, the inorganic solid electrolyte can include one or more of oxide solid electrolytes (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superionic conductor (lithium germanium phosphorus sulfide, argyrodite), amorphous sulfide), and halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0075] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0076] In some embodiments, the electrode assembly is in a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound into the jelly-roll structure.

[0077] In some embodiments, the electrode assembly is in a stack structure.

[0078] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be alternately stacked.

[0079] As an example, a plurality of separators can be provided, and each of the plurality of separators can be disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0080] As an example, the separators can be continuously provided and disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0081] In some embodiments, the electrode assembly can have a cylindrical shape, a flat shape, or a multi-prism shape.

[0082] In some embodiments, the electrode assembly can be provided with a tab. The tab can be used to conduct current from the electrode assembly. The tab can include a positive tab and a negative tab.

[0083] In some embodiments, the battery cell can include a housing. The housing can be used to encapsulate components such as the electrode assembly and the electrolyte. The battery cell can be a cylindrical battery cell.

[0084] A battery apparatus as referred to in embodiments of the present application can include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly can include a plurality of battery cells connected in series, in parallel, or in a mixed connection through a busbar.

[0085] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells; as an example, the battery cell assembly can be a battery module formed by arranging and fixing a plurality of battery cells into a single independent module.

[0086] As an example, a battery module can be formed by bundling a plurality of battery cells with a cable tie.

[0087] In some embodiments, a battery apparatus can be a battery pack. The battery pack can include a housing and one or more battery cell assemblies. The battery cell assemblies can be housed in the housing.

[0088] As an example, the battery cell assembly can be a battery module. The battery cell assembly can be housed in the housing by fixing the battery module in the housing.

[0089] As an example, the battery cell assembly can also be housed in the housing by directly fixing a plurality of battery cells in the housing.

[0090] As an example, the housing can include a first housing and a second housing. The first housing and the second housing can be coupled so that an enclosed space is formed inside the housing to accommodate the battery cell assembly. Here, enclosed means covered or closed, which can be sealed or unsealed. The first housing can be a top cover or a bottom plate.

[0091] As an example, the housing can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate can be coupled to the frame so that an enclosed space is formed inside the housing to accommodate the battery cell assembly.

[0092] As an example, the box can be part of a chassis structure of a vehicle. For example, the top cover of the box can be at least part of a floor of the vehicle, or the frame of the box can be at least part of a cross beam and a longitudinal beam of the vehicle.

[0093] In some embodiments, the battery device refers to an energy storage device, and the energy storage device includes a box, at least one side of the box is provided with a door. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0094] For a cylindrical battery cell, the cylindrical battery cell generally includes a shell and an electrode assembly, and the electrode assembly is contained in the shell. The shell can include a shell body and an end cover, the shell body has an opening, and the electrode assembly is loaded into the shell body, and the opening of the shell body can be closed by the end cover to form a receiving space inside the shell to accommodate the electrode assembly.

[0095] To realize the stable connection of the end cover and the shell, the end cover can be welded to the shell. However, for the cylindrical battery cell whose material of the end cover and the material of the shell both include steel and the outer diameter of the shell is greater than or equal to 40 mm, the cylindrical battery cell has the characteristics of large volume and large capacity, and in the process of use, as the internal pressure of the cylindrical battery cell changes, the end cover is more likely to deform, which easily leads to welding failure of the end cover and the shell, affecting the service life of the battery cell.

[0096] Based on the above considerations, to alleviate the problem of easy welding failure of the end cover and the shell, the embodiments of the present application provide a cylindrical battery cell, which includes a shell, an end cover and an electrode assembly; the shell forms an opening at least at one end of the cylindrical battery cell in the axial direction, the material of the shell includes steel, the outer diameter of the shell is D, and D≥40 mm; the end cover closes the opening, and the end cover and the shell jointly define a receiving space, the material of the end cover includes steel; the electrode assembly is contained in the receiving space; wherein the end cover is welded to the shell to form a fusion portion, and the effective penetration depth of the fusion portion is H, and 0.15 mm≤H≤0.9 mm.

[0097] In such a cylindrical battery cell, the effective penetration depth of the fusion portion formed by welding the end cover to 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 at the same time reduces the welding difficulty of the end cover and the shell. In this way, the welding strength and welding difficulty of the end cover and the shell are taken into account, and the service life of the cylindrical battery cell is improved.

[0098] The technical solutions described in the embodiments of the present application are applicable to various electric devices using cylindrical battery cells and battery devices, such as mobile phones, portable devices, notebook computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, etc. For example, the spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc.

[0099] The following embodiments are described by taking a vehicle as an example for convenience of illustration.

[0100] Referring to FIG. 1, FIG. 1 is a structural schematic diagram of a vehicle 1000 according to some embodiments of the present application. The vehicle 1000 is internally provided with a battery device 100, which can be arranged at the bottom, head or tail of the vehicle 1000. The battery device 100 can be used for power supply of the vehicle 1000, for example, the battery device 100 can be used as an operating power supply of the vehicle 1000.

[0101] The vehicle 1000 can further include a controller 200 and a motor 300, the controller 200 being used to control the battery device 100 to supply power to the motor 300, for example, to meet the power demand of the vehicle 1000 during starting, navigation and driving.

[0102] In some embodiments of the present application, the battery device 100 can not only be used as an operating power supply of the vehicle 1000, but also be used as a driving power supply of the vehicle 1000, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1000.

[0103] Referring to FIG. 2, FIG. 2 is an exploded view of the battery device 100 according to some embodiments of the present application. The battery device 100 can include a cylindrical battery cell 10 and a box 20, the box 20 being used to accommodate the cylindrical battery cell 10.

[0104] The box 20 has an enclosed space for accommodating the cylindrical battery cell 10, and the box 20 can have various structures. In some embodiments, the box 20 can include a first box 201 and a second box 202, the first box 201 being engaged with the second box 202. The first box 201 and the second box 202 can have various shapes, such as a cuboid, a cylinder, etc. The first box 201 can be a hollow structure with one side open, and the second box 202 can also be a hollow structure with one side open. The open side of the second box 202 is engaged with the open side of the first box 201, so as to form the box 20 with the enclosed space. Alternatively, the first box 201 can be a hollow structure with one side open, and the second box 202 can be a plate structure, which is engaged with the open side of the first box 201, so as to form the box 20 with the enclosed space.

[0105] In the battery device 100, the cylindrical battery cell 10 can be one or multiple. If the cylindrical battery cell 10 is multiple, the multiple cylindrical battery cells 10 can be connected in series, in parallel, or in a mixed connection. The mixed connection means that the multiple cylindrical battery cells 10 are connected in series and in parallel. The multiple cylindrical battery cells 10 can be connected in series, in parallel, or in a mixed connection to form a battery module, and the multiple battery modules can be connected in series, in parallel, or in a mixed connection to form a whole, and the whole can be accommodated in the box 20. Alternatively, all the cylindrical battery cells 10 can be directly connected in series, in parallel, or in a mixed connection, and the whole formed by the cylindrical battery cells 10 can be accommodated in the box 20.

[0106] In some embodiments, the battery device 100 can further include a busbar component. The multiple cylindrical battery cells 10 can be electrically connected through the busbar component to achieve the series connection, the parallel connection, or the mixed connection of the multiple cylindrical battery cells 10. The busbar component can be a metal conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, or the like.

[0107] Please refer to FIG. 3 and FIG. 4. FIG. 3 is an exploded view of the cylindrical battery cell 10 according to some embodiments of the present application. FIG. 4 is an axonometric view of the cylindrical battery cell 10 shown in FIG. 3. The cylindrical battery cell 10 can include a housing 1 and an electrode assembly 2, and the electrode assembly 2 can be accommodated in the housing 1.

[0108] In some embodiments, the housing 1 can include a shell 11 and an end cover 12. The shell 11 has an opening, and the end cover 12 closes the opening of the shell 11. Here, closing means covering or closing, which can be sealed or unsealed.

[0109] The shell 11 is a component for accommodating the electrode assembly 2. The shell 11 is in the shape of a cylinder. The shell 11 can be a hollow structure with an opening at one end. Alternatively, the shell 11 can be a hollow structure with openings at opposite ends. The electrode assembly 2 can be partially located in the shell 11 or entirely located in the shell 11.

[0110] The end cover 12 cooperates with the shell 11 to define a receiving space 13 (not shown in FIG. 3 and FIG. 4) for accommodating the electrode assembly 2 and other components. The end cover 12 can be welded to the shell 11 to close the opening of the shell 11. The end cover 12 can be in the shape of a circular plate that matches the shape of the shell 11.

[0111] In the embodiment in which the shell 11 has an opening at one end, one end cover 12 can be provided. In the embodiment in which the shell 11 has openings at opposite ends, two end covers 12 can be provided. The two end covers 12 close the two openings of the shell 11, respectively, and the two end covers 12 cooperates with the shell 11 to define the receiving space 13.

[0112] In some embodiments, the cylindrical battery cell 10 can further include an electrode terminal 3 disposed on the shell 1, the electrode terminal 3 being electrically connected to the tab of the electrode assembly 2 to input or output the electric energy of the cylindrical battery cell 10. The electrode terminal 3 can be disposed on the shell body 11 of the shell 1 or on the end cover 12 of the shell 1. The electrode terminal 3 can be directly connected to the tab, for example, the electrode terminal 3 is welded to the tab. The electrode terminal 3 can also be indirectly connected to the tab, for example, the electrode terminal 3 is indirectly connected to the tab through a current collecting member. The current collecting member can be a metal conductor, for example, copper, iron, aluminum, steel, aluminum alloy, etc.

[0113] As an example, as shown in FIGS. 3 and 4, the shell body 11 forms an opening at one end, the shell 1 has one end cover 12, and one end cover 12 closes one opening of the shell body 11. The shell body 11 is provided with an electrode terminal 3 at the end opposite to the end cover 12, and the electrode assembly 2 forms a first tab 21 and a second tab 22 at opposite ends, respectively. The first tab 21 is electrically connected to the end cover 12 through a first current collecting member 4, and the second tab 22 is electrically connected to the electrode terminal 3 through a second current collecting member 5. Among them, one of the first tab 21 and the second tab 22 is a positive electrode tab, and the other is a negative electrode tab.

[0114] Please refer to FIGS. 5 and 6, FIG. 5 is a partial view of the cylindrical battery cell 10 provided by some embodiments of the present application; and FIG. 6 is a partial enlarged view of A in FIG. 5. The embodiments of the present application provide a cylindrical battery cell 10, which includes a shell body 11, an end cover 12 and an electrode assembly 2. The shell body 11 forms an opening at at least one end along the axial direction Z of the cylindrical battery cell 10, the material of the shell body 11 includes steel, the outer diameter of the shell body 11 is D, and D≥40mm. The end cover 12 closes the opening, and the end cover 12 and the shell body 11 jointly define a receiving space 13 in which the electrode assembly 2 is accommodated. The material of the end cover 12 includes steel. Among them, the end cover 12 and the shell body 11 are welded to form a fusion portion 14, and the effective fusion depth of the fusion portion 14 is H, and 0.15mm≤H≤0.9mm.

[0115] Along the axial direction Z of the cylindrical battery cell 10, the shell body 11 can form an opening at only one end, and the end cover 12 is correspondingly provided at one end. The shell body 11 can also form an opening at opposite ends, and the end cover 12 is correspondingly provided at two ends.

[0116] The shell body 11 includes a side wall 111 surrounding the outer side of the electrode assembly 2, and the cross section of the side wall 111 is annular, which is perpendicular to the axial direction Z of the cylindrical battery cell 10. In the embodiment in which the shell body 11 forms an opening at only one end, the shell body 11 can further include a bottom wall disposed at the end of the side wall 111 away from the end cover 12, and the bottom wall and the side wall 111 can be integrally formed. In the embodiment in which the shell body 11 forms an opening at opposite ends, the side wall 111 is the shell body 11.

[0117] The material of the shell 11 includes steel, and the shell 11 can be made of steel material. The shell 11 can be entirely of steel material, or a part of the shell 11 can be of steel material, for example, the shell 11 includes a first base material and a first protective layer arranged on the surface of the first base material, the first base material is of steel material, and the first protective layer is of non-steel material. The first protective layer can be an anti-oxidation layer, for example, the first protective layer is a nickel layer plated on the surface of the second base material.

[0118] The outer diameter of the shell 11 is the diameter of the outer circumferential surface of the side wall 111 of the shell 11. D can take any one of 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, or a range value between any two of them.

[0119] The material of the end cover 12 includes steel, and the end cover 12 can be made of steel material. The end cover 12 can be entirely of steel material, or a part of the end cover 12 can be of steel material, for example, the end cover 12 includes a second base material and a second protective layer arranged on the surface of the second base material, the second base material is of steel material, and the second protective layer is of non-steel material. The second protective layer can be an anti-oxidation layer, for example, the second protective layer is a nickel layer plated on the surface of the second base material. Steel can include carbon steel, stainless steel, etc.

[0120] The electrode assembly 2 can be substantially cylindrical, and the electrode assembly 2 can be a winding structure or a laminated structure.

[0121] The fusion portion 14 is a portion fused together after the end cover 12 and the shell 11 are welded, and the fusion portion 14 can be a welding mark portion formed by welding the end cover 12 and the shell 11. The fusion portion 14 serves to connect the end cover 12 and the shell 11, and the fusion portion 14 can be formed in part on the end cover 12 and in part on the shell 11. The end cover 12 and the shell 11 can be welded to form one fusion portion 14, for example, the fusion portion 14 is an annular structure, the fusion portion 14 extends along the circumference of the opening of the shell 11, and the end cover 12 and the shell 11 can be sealingly connected through the fusion portion 14; the end cover 12 and the shell 11 can also be welded to form multiple fusion portions 14, and the multiple fusion portions 14 are arranged along the circumference of the opening of the shell 11.

[0122] H can take any one of 0.15 mm, 0.18 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, etc., or a range value between any two of them.

[0123] For the cylindrical battery monomer 10 in which the material of the end cover 12 and the material of the shell 11 both include steel and the outer diameter of the shell 11 is greater than or equal to 40 mm, the cylindrical battery monomer 10 has the characteristics of large volume and large capacity. In the use process of the cylindrical battery monomer 10, as the internal pressure of the cylindrical battery monomer 10 changes, the end cover 12 is more likely to deform, which is easy to cause the welding failure of the end cover 12 and the shell 11.

[0124] In the embodiment of the present application, H≥0.15 mm, which increases the welding strength of the end cover 12 and the shell 11 and reduces the risk of welding failure of the end cover 12 and the shell 11. H≤0.9 mm, which reduces the welding difficulty of the end cover 12 and the shell 11. That is, the effective penetration of the fusion portion 14 formed by welding the end cover 12 and the shell 11 is controlled within the range of 0.15 mm-0.9 mm, which takes into account the welding strength and welding difficulty of the end cover 12 and the shell 11, and improves the service life of the cylindrical battery monomer 10.

[0125] In some embodiments, 0.25 mm≤H≤0.5 mm.

[0126] In the embodiment, H can take any one of 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.35 mm, 0.36 mm, 0.37 mm, 0.38 mm, 0.39 mm, 0.4 mm, 0.41 mm, 0.42 mm, 0.43 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.47 mm, 0.48 mm, 0.49 mm, 0.5 mm, etc. or a range value between any two of them.

[0127] In the embodiment, H≥0.25 mm, which further increases the effective penetration of the fusion portion 14 and further increases the welding strength of the end cover 12 and the shell 11; H≤0.5 mm, which further reduces the welding difficulty of the end cover 12 and the shell 11.

[0128] In some embodiments, please refer to FIG. 7 and FIG. 8, FIG. 7 is a structural schematic diagram of the end cover 12 shown in FIG. 5; and FIG. 8 is a partial enlarged view of C in FIG. 7. The end cover 12 is provided with a pressure relief groove 121, and the end cover 12 is configured to be able to split along at least a part of the pressure relief groove 121 when the cylindrical battery monomer 10 is relieved.

[0129] 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 cover 12 by punching, milling, laser etching, etc.

[0130] The end cover 12 forms a weak portion 1211 at the position where the pressure relief groove 121 is arranged, which can be the groove bottom wall of the pressure relief groove 121. The weak portion 1211 can be an equal-thickness structure or a non-equal-thickness structure. As an example, in the embodiment shown in FIG. 8, the weak portion 1211 is a non-equal-thickness structure, and 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, and the thickness direction of the weak portion 1211 is parallel to the axial direction Z of the cylindrical battery cell 10.

[0131] 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.

[0132] The end cover 12 is arranged with the pressure relief groove 121, so that the end cover 12 forms an integrated pressure relief mechanism, and the end cover 12 has a pressure relief function. When the internal pressure of the cylindrical battery cell 10 reaches the burst pressure of the end cover 12, the end cover 12 can be ruptured along at least a portion of the pressure relief groove 121, so that a local area of the end cover 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 effectively improving the reliability of the cylindrical battery cell 10.

[0133] In some embodiments, please continue to refer to FIGS. 6 and 8, the minimum residual thickness of the pressure relief groove 121 is L1, and 0.067≤L1 / H≤0.67.

[0134] The minimum residual thickness of the pressure relief groove 121 is the minimum thickness of the weak portion 1211, and the thickness of the thinnest position of the weak portion 1211 is the minimum thickness of the weak portion 1211.

[0135] L1 / H can take any one of 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 a range value between any two of them.

[0136] For the cylindrical battery cell 10 with the outer diameter of the shell 11 greater than or equal to 40 mm, the internal space utilization is high, and when the cylindrical battery cell 10 is in thermal runaway, the internal pressure of the cylindrical battery cell 10 gradually increases, and the end cover 12 will eventually partially open to release pressure. Although the discharge of the cylindrical battery cell 10 can be discharged from the partially opened area of the end cover 12, the internal pressure of the cylindrical battery cell 10 can still continue to rise during the discharge of the discharge to the outside, which can easily cause the welding failure of the end cover 12 and the shell 11, resulting in the separation of the end cover 12 and the shell 11, and the explosion of the cylindrical battery cell 10.

[0137] However, in the present embodiment, L1 / H≤0.67, so that the pressure required for the separation of the end cover 12 and the shell 11 is far from the burst pressure of the end cover 12, so that the cylindrical battery cell 10 is not easy to cause the separation of the end cover 12 and the shell 11 during the pressure relief of the end cover 12. And L1 / H≥0.067, which can reduce the risk of fatigue cracking of the end cover 12 at the position of the pressure relief groove 121 during the normal life cycle.

[0138] In some embodiments, 0.12≤L1 / H≤0.48.

[0139] L1 / H can take any one of the following values: 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, or a range value between any two of them.

[0140] In the present embodiment, L1 / H≥0.12, which further reduces the risk of separation of the end cover 12 and the shell 11 during the pressure relief of the cylindrical battery cell 10 through the end cover 12. L1 / H≤0.48, which can further reduce the risk of fatigue cracking of the end cover 12 at the position of the pressure relief groove 121 during the normal life cycle.

[0141] In some embodiments, please continue to refer to FIGS. 6 and 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.

[0142] The side wall 111 of the shell 11 can be an equal-thickness structure or a non-equal-thickness structure. If the thickness of the side wall 111 of the shell 11 is a non-equal-thickness structure, the wall thickness of the side wall 111 is the thickness at the thinnest position of the side wall 111.

[0143] L1 / L2 can take any one of the point values 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, or a range between any two of these values.

[0144] In this embodiment, 0.07≤L1 / L2≤0.5, which can effectively reduce the risk of the shell 11 being damaged when the cylindrical battery cell 10 is in thermal runaway.

[0145] In some embodiments, the minimum residual thickness of the pressure relief groove 121 is L1, and 0.06mm≤L1≤0.2mm.

[0146] L1 can take any one of the point values 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, or a range between any two of these values.

[0147] For the end cover 12 made of steel, L1≥0.06mm, the end cover 12 has sufficient strength at the location of the pressure relief groove 121, reducing the risk of fatigue cracking of the end cover 12 at the location of the pressure relief groove 121 during the normal life cycle. L1≤0.2mm, so that the burst pressure of the end cover 12 is not too large, and the end cover 12 can be more timely cracked along the pressure relief groove 121 when the cylindrical battery cell 10 is in thermal runaway.

[0148] In some embodiments, please continue to refer to FIGS. 5 and 7, the pressure relief groove 121 is an annular groove, and the inner diameter of the pressure relief groove 121 is d, and 0.5≤d / D≤0.8.

[0149] The annular groove is a groove extending along a circular track. The pressure relief groove 121 has a groove opening, and it can be understood that the groove opening of the pressure relief groove 121 is annular, and the inner diameter of the groove opening of the pressure relief groove 121 is the inner diameter of the pressure relief groove 121.

[0150] The pressure relief groove 121 defines a pressure relief area, and the weak portion 1211 is arranged around the pressure relief area. When the end cover 12 is cracked along the pressure relief groove 121, the pressure relief area will be opened, and the end cover 12 forms a pressure relief channel at the position corresponding to the pressure relief area, and the discharge inside the cylindrical battery cell 10 can be discharged through the pressure relief channel.

[0151] d / D can take any one of the point values 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, or a range between any two of these values.

[0152] d / D≥0.5, so that the area of the pressure relief area defined by the pressure relief groove 121 is larger, and the end cover 12 has a larger pressure relief area, so that the internal exhaust of the cylindrical battery cell 10 can be quickly discharged when thermal runaway occurs, and the risk of separation of the end cover 12 from the shell 11 can be reduced. d / D≤0.8, so that the deformation of the pressure relief area defined by the pressure relief groove 121 due to the change of the internal pressure of the cylindrical battery cell 10 during the normal life cycle is not too large, reducing the influence of the deformation of the pressure relief area on the end cover 12 at the position of the pressure relief groove 121, and reducing the risk of fatigue cracking of the end cover 12 at the position of the pressure relief groove 121.

[0153] In some embodiments, please continue to refer to FIG. 6, the thickness of the end cover 12 is L3, and the wall thickness of the side wall 111 of the shell 11 is L2, and 0.3≤L2 / L3≤1.2.

[0154] In the embodiments in which the end cover 12 is provided with the pressure relief groove 121, the thickness of the thinnest position in the area of the end cover 12 other than the weakened portion 1211 is the thickness of the end cover 12.

[0155] 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

[0156] L2 / L3 can take any one of 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, etc. Point value or range value between any two.

[0157] L2 / L3≥0.3, so that the ratio of the thickness of the end cover 12 to the wall thickness of the side wall 111 of the shell 11 is not too large, and in the case that the thickness of the side wall 111 of the shell 11 meets the use requirements, the use of the end cover 12 is reduced, and the manufacturing cost of the end cover 12 is reduced. L2 / L3≤1.2, so that the ratio of the thickness of the end cover 12 to the wall thickness of the side wall 111 of the shell 11 is not too large, and in the case that the thickness of the side wall 111 of the shell 11 meets the use requirements, the end cover 12 has sufficient strength and deformation resistance.

[0158] In some embodiments, 0.6≤L2 / L3≤1.

[0159] 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.

[0160] 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.

[0161] In some embodiments, 0.3mm≤L2≤0.6mm; and / or, 0.3mm≤L3≤1mm.

[0162] 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.

[0163] 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.

[0164] For the shell 11 made of steel, L2≥0.3 mm, so that the shell 11 has a 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 monomer 10. For the end cover 12 made of steel, L3≥0.3 mm, so that the end cover 12 has a 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.

[0165] In some embodiments, please continue to refer to FIG. 7, the end cover 12 includes a body part 122, a first protruding part 123, and an edge part 124. The body part 122 has a first surface 1221 facing the electrode assembly 2 along the axial direction Z of the cylindrical battery monomer 10. The first protruding part 123 is arranged around the outer edge of the body part 122 and protrudes from the first surface 1221, and the first protruding part 123 is at least partially inserted into the shell 11. The edge part 124 is arranged around the outer edge of the first protruding part 123, and the edge part 124 abuts against the end of the shell 11 where the opening is formed, and the edge part 124 is welded with the shell 11 to form the fusion part 14.

[0166] As shown in FIG. 7, the body part 122 and the first protruding part 123 can be divided by a first edge U, which is the outer edge of the body part 122. The edge part 124 and the first protruding part 123 can be divided by a second edge V, which is the outer edge of the first protruding part 123. In FIG. 7, the first edge U and the second edge V are both shown by dashed lines.

[0167] The body part 122 can be a circular structure, and the first protruding part 123 and the edge part 124 can be annular structures.

[0168] The part of the first protruding part 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 part 123 and the inner peripheral surface of the side wall 111 of the shell 11 are in contact with each other.

[0169] 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.

[0170] As an example, the thickness of the body part 122 is the thickness of the end cover 12, 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 slot of the pressure relief groove 121 is formed on the surface of the second protruding part 128 facing away from the first surface 1221. Among them, the second groove 127 can provide opening space for the pressure relief area of the end cover 12.

[0171] In this 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 one end of the shell 11 which is provided with an 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 process of the edge part 124 and the shell 11, whether the edge part 124 and the shell 11 are welded 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 process of the edge part 124 and the shell 11, reducing the risk of damage to the electrode assembly 2 caused by the high-temperature substances entering the accommodation space 13.

[0172] In some embodiments, referring to FIG. 6 and FIG. 9, which is an enlarged view of the portion B in FIG. 6 (the housing 11 is removed in FIG. 9). The end cap 12 has a contact interface 125 in contact with the housing 11, the contact interface 125 includes a first interface 1251 extending from the fusion portion 14 to the accommodation space 13, the first interface 1251 is connected to a first position 1251a on the surface of the fusion portion 14. 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, 2≤L4 / H≤20.

[0173] The contact interface 125 is the surface of the end cap 12 in contact with the housing 11. In embodiments in which the end cap 12 includes the body portion 122, the first protrusion 123, and the edge portion 124, the contact interface 125 can be partially located on the edge portion 124 and partially located on the first protrusion 123, that is, both the edge portion 124 and the first protrusion 123 are in contact with the housing 11.

[0174] The first interface 1251 is the portion of the contact interface 125 extending from the fusion portion 14 to the accommodation space 13. The first interface 1251 can be a part of the contact interface 125, or the first interface 1251 can be the contact interface 125. The first interface 1251 can be completely located on the first protrusion 123, for example, the outer peripheral surface of the first protrusion 123 is the first interface 1251; or the first interface 1251 can be partially located on the first protrusion 123 and partially located on the edge portion 124.

[0175] As an example, in the embodiment shown in FIG. 6 and FIG. 9, the contact interface 125 further includes a second interface 1252, the second interface 1252 and the first interface 1251 are separated by the fusion portion 14, the second interface 1252 extends from the fusion portion 14 to the outside of the cylindrical battery cell 10, the second interface 1252 is connected to a second position 1252a on the surface of the fusion portion 14, the minimum distance between the first position 1251a and the second position 1252a is the effective fusion 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 peripheral 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 the end of the housing 11 having the opening, a part of the inner end surface of the edge portion 124 is the second portion 12512 of the first interface 1251, and another part of the inner end surface of the edge portion 124 is the second interface 1252.

[0176] The second surface 1231 can be a surface of the end cover 12 closest to the electrode assembly 2 along the axial direction Z of the cylindrical battery cell 10, and the second surface 1231 can directly abut against the electrode assembly 2 or indirectly abut against the electrode assembly 2 through an intermediate piece.

[0177] 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 take any one of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or a range value between any two of them.

[0178] When the cylindrical battery cell 10 is in thermal runaway, the smaller L4 / H is, the easier the fusion portion 14 is to crack from the first position 1251a, and the welding failure of the end cover 12 and the shell 11 is caused. However, L4 / H≥2 can effectively reduce the risk of welding failure of the end cover 12 and the shell 11 when the cylindrical battery cell 10 is in thermal runaway, thereby reducing the risk of separation of the end cover 12 and the shell 11. L4 / H≤20, in the case that the effective penetration depth of the fusion portion 14 reaches the use requirement, the minimum distance between the first position 1251a and the second surface 1231 is not too large, the space occupation of the first protruding portion 123 is reduced, and more space is left for the electrode assembly 2, which is conducive to improving the volumetric energy density of the cylindrical battery cell 10.

[0179] In some embodiments, 2.5≤L4 / H≤10.

[0180] In the present embodiment, L4 / H can take any one of 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or a range value between any two of them.

[0181] L4 / H≥2.5 can further reduce the risk of separation of the end cover 12 and the shell 11 when the cylindrical battery cell 10 is in thermal runaway. L4 / H≤10 can further improve the volumetric energy density of the cylindrical battery cell 10.

[0182] In some embodiments, please continue to refer to FIG. 6, the cylindrical battery cell 10 further includes a first current collecting member 4, the first current collecting member 4 is contained in the receiving space 13, and 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 tab 21, and the first current collecting member 4 connects the first tab 21 and the first protruding portion 123.

[0183] The first current collecting member 4 can be a metal conductor, and the first current collecting member 4 can be in the form of a disc. The first current collecting member 4 can also be referred to as a current collecting disc.

[0184] The first tab 21 can be a positive electrode tab or a negative electrode tab.

[0185] The first current collecting member 4 connects the first tab 21 and the first protrusion 123, and realizes the electrical connection between the electrode assembly 2 and the end cover 12. In the axial direction Z of the cylindrical battery monomer 10, the second surface 1231 of the first protrusion 123 abuts against the current collecting member, and the current collecting member abuts against the first tab 21. The first current collecting member 4 and the first tab 21 can be connected by welding, bonding or the like; the first current collecting member 4 and the first protrusion 123 can also be connected by welding, bonding or the like.

[0186] In the present embodiment, the first tab 21 and the first protrusion 123 are effectively electrically connected through the first current collecting member 4, and the electrode assembly 2 and the end cover 12 are electrically connected.

[0187] In some embodiments, please continue to refer to FIG. 6, the first protrusion 123 is welded with the first current collecting member 4, and the area corresponding to the first protrusion 123 on the side of the end cover 12 away from the electrode assembly 2 is formed with a first groove 126.

[0188] As an example, the first groove 126 is an annular groove.

[0189] When the end cover 12 is formed, the first groove 126 can be punched on the plate to correspond to the formation of the first protrusion 123, thereby reducing the forming difficulty of the first protrusion 123. The thickness of the plate is the thickness of the end cover 12.

[0190] The first groove 126 can play a marking role, when the end cover 12 is welded with the first current collecting member 4, the first protrusion 123 and the first current collecting member 4 can be welded along the first groove 126 to accurately weld the first protrusion 123 and the first current collecting member 4, thereby improving the accuracy of welding. In addition, the first protrusion 123 and the first current collecting member 4 can be welded together from the outside of the end cover 12 by means of penetration welding, thereby realizing the stable connection of the first protrusion 123 and the first current collecting member 4.

[0191] In some embodiments, referring to FIGS. 10-12, FIG. 10 is a partial view of a cylindrical battery cell 10 according to some embodiments of the application; FIG. 11 is a partial enlarged view of E in FIG. 10; and FIG. 12 is a partial enlarged view of F in FIG. 11 (the housing 11 is removed in FIG. 12). The end cap 12 has a contact interface 125 in contact with 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 to the accommodation 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.

[0192] As an example, the outer circumferential surface 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, and the second interface 1252 is connected to the outer circumferential surface of the edge portion 124. It can be understood that a part of the surface of the fusion portion 14 connects the first interface 1251 and the second interface 1252.

[0193] As an example, the fusion portion 14 has a ring structure, the first interface 1251 is connected to the surface of the fusion portion 14 at a first circle, the second interface 1252 is connected to the surface of the fusion portion 14 at a second circle, the diameter of the second circle is greater than the diameter of the first circle, and the minimum distance between the first circle and the second circle is the minimum distance between the first position 1251a and the second position 1252a. The cross-sectional dimension of the fusion portion 14 in the radial direction of the cylindrical battery cell 10 gradually decreases in the direction of the end cap 12 pointing to the electrode assembly 2, and the cross-section of the fusion portion 14 is parallel to the radial direction of the cylindrical battery cell 10.

[0194] In some embodiments, referring to FIGS. 13-15, FIG. 13 is a partial view of a cylindrical battery cell 10 according to some other embodiments of the application; FIG. 14 is a partial enlarged view of G in FIG. 13; and FIG. 15 is a partial enlarged view of I in FIG. 14 (the housing 11 is removed in FIG. 15). The surface of the fusion portion 14 includes a third surface 141 connecting the outer surface of the end cap 12 and the outer surface of the housing 11. The end cap 12 has a contact interface 125 in contact with the housing 11, the contact interface 125 includes a first interface 1251 extending from the fusion portion 14 to the accommodation space 13, and the first interface 1251 is connected to the surface of the fusion portion 14 at a first position 1251a, and the minimum distance between the first position 1251a and the third surface 141 is the effective fusion depth of the fusion portion 14.

[0195] The third surface 141 is a portion of the surface of the fusion portion 14 connecting the outer surface of the end cover 12 and the outer surface of the shell 11. In FIGS. 14 and 15, the third surface 141 is shown with thick lines. The portion of the surface of the end cover 12 exposed outside the cylindrical battery cell 10 is the outer surface of the end cover 12, and the portion of the surface of the shell 11 exposed outside the cylindrical battery cell 10 is the outer surface of the shell 11.

[0196] The first interface 1251 can be located entirely in 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 can also be partially located in the first protruding portion 123 and partially located in the edge portion 124.

[0197] As an example, in the embodiment shown in FIGS. 14 and 15, the edge portion 124 of the end cover 12 can have an inner end surface and an outer end surface arranged opposite 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 shell 11 where the opening is formed, and the outer end surface of the edge portion 124 belongs to the outer surface of the end cover 12. The outer peripheral surface of the side wall 111 of the shell 11 belongs to the outer surface of the shell 11, and the third surface 141 connects the outer peripheral surface of the side wall 111 of the shell 11 and the outer end surface of the edge portion 124 of the end cover 12. The first interface 1251 includes a first portion 12511 and a second portion 12512. The first portion 12511 is the outer peripheral surface of the first protruding portion 123, and the second portion 12512 is the inner end surface of the edge portion 124. The outer peripheral surface of the first protruding portion 123 is connected to the inner end surface of the edge portion 124.

[0198] As an example, the fusion portion 14 has a ring structure, the first interface 1251 is formed as a first circle at the position where the first interface 1251 is connected to the surface of the fusion portion 14, and the third surface 141 is a surface of revolution. 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 in the direction in which the edge portion 124 points to the body portion 122, and the cross section of the fusion portion 14 is parallel to the radial direction of the cylindrical battery cell 10. In the embodiment shown in FIGS. 14 and 15, the distance between the first position 1251a and the third surface 141 in the plane where the second portion 12512 is located is equal to the minimum distance between the first position 1251a and the third surface 141.

[0199] The embodiments of the present application provide a battery device 100, which includes the cylindrical battery cell 10 provided by any one of the embodiments described above.

[0200] The embodiments of the present application provide an electric device, which includes the cylindrical battery cell 10 provided by any one of the embodiments described above or the battery device 100 provided by any one of the embodiments described above.

[0201] The application also provides a cylindrical battery cell 10, which comprises a shell 11, an end cover 12, an electrode assembly 2, an electrode terminal 3, a first current collecting member 4 and a second current collecting member 5. The shell 11 has an outer diameter D, D≥40mm, and is made of steel. The shell 11 is formed with an opening at only one end in the axial direction Z of the cylindrical battery cell 10, and the end cover 12 closes the opening of the shell 11. The end cover 12 and the shell 11 jointly define a receiving space 13, and the end cover 12 is made of steel. The electrode assembly 2, the first current collecting member 4 and the second current collecting member 5 are all accommodated in the receiving space 13. In the axial direction Z of the cylindrical battery cell 10, the electrode assembly 2 is formed with a first tab 21 and a second tab 22 at opposite ends, respectively. The first tab 21 is electrically connected to the end cover 12 through the first current collecting member 4, and the second tab 22 is electrically connected to the electrode terminal 3 through the second current collecting member 5. The electrode terminal 3 is arranged at the end of the shell 11 opposite to the end cover 12.

[0202] The end cover 12 comprises 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 in 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. The first protruding portion 123 is at least partially inserted into the shell 11 and abuts against the electrode assembly 2 through the first current collecting member 4. In the axial direction Z of the cylindrical battery cell 10, the first protruding portion 123 has a second surface 1231 facing the electrode assembly 2, and the second surface 1231 abuts against the first current collecting member 4. The edge portion 124 is arranged around the outer edge of the first protruding portion 123 and abuts against the end of the shell 11 where the opening is formed. The edge portion 124 is welded to the shell 11 to form a fusion portion 14. The body portion 122 is provided with a pressure relief groove 121, which is an annular groove. The end cover 12 is configured to be broken along at least part of the pressure relief groove 121 when the cylindrical battery cell 10 is relieved of pressure.

[0203] The end cover 12 has a contact interface 125 in contact with the shell 11. The contact interface 125 comprises a first interface 1251 and a second interface 1252, which 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 penetration depth of the fusion portion 14.

[0204] 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 melting 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.

[0205] The application further provides a cylindrical battery monomer 10, which comprises a shell 11, an end cover 12, an electrode assembly 2, an electrode terminal 3, a first current collecting member 4 and a second current collecting member 5. The outer diameter of the shell 11 is D, D≥40mm, and the material of the shell 11 comprises steel. The shell 11 is formed with an opening at only one end in the axial direction Z of the cylindrical battery monomer 10, and the end cover 12 closes the opening of the shell 11. The end cover 12 and the shell 11 jointly define a receiving space 13, and the material of the end cover 12 comprises steel. The electrode assembly 2, the first current collecting member 4 and the second current collecting member 5 are all accommodated in the receiving space 13. In the axial direction Z of the cylindrical battery monomer 10, the opposite ends of the electrode assembly 2 are respectively formed with a first tab 21 and a second tab 22. The first tab 21 is electrically connected to the end cover 12 through the first current collecting member 4, the second tab 22 is electrically connected to the electrode terminal 3 through the second current collecting member 5, and the electrode terminal 3 is arranged at the opposite end of the shell 11 and the end cover 12.

[0206] The end cover 12 comprises 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 in the axial direction Z of the cylindrical battery monomer 10. The first protruding portion 123 is arranged 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 shell 11 and abuts against the electrode assembly 2 through the first current collecting member 4. In the axial direction Z of the cylindrical battery monomer 10, the first protruding portion 123 has a second surface 1231 facing the electrode assembly 2, and the second surface 1231 abuts against the first current collecting member 4. The edge portion 124 is arranged around the outer edge of the first protruding portion 123, and the edge portion 124 abuts against the end of the shell 11 where the opening is formed. The edge portion 124 is welded to the shell 11 to form a fusion portion 14. The body portion 122 is provided with a pressure relief groove 121, which is an annular groove. The end cover 12 is configured to be split along at least part of the pressure relief groove 121 when the cylindrical battery monomer 10 is relieved of pressure.

[0207] The surface of the fusion portion 14 includes a third surface 141 connecting 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 accommodation space 13, the first interface 1251 is connected to the third surface 141 at a first position 1251a, and the minimum distance between the first position 1251a and the third surface 141 is the effective fusion depth of the fusion portion 14.

[0208] Wherein, 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 fusion 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.

[0209] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0210] The above embodiments are only used to illustrate the technical solutions of the present application, and are not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

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

2. The cylindrical battery cell of claim 1, wherein, 0.25mm≤H≤0.5mm.

3. The cylindrical battery cell of claim 1 or 2, wherein, 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.

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

67.

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

48.

6. The cylindrical battery cell of any one of claims 3-5, wherein, A minimum residual thickness of the pressure relief groove is L1, a wall thickness of a side wall of the shell is L2, 0.07≤L1 / L2≤0.

5.

7. The cylindrical battery cell of any one of claims 3-6, wherein, A minimum residual thickness of the pressure relief groove is L1, 0.06mm≤L1≤0.2mm.

8. The cylindrical battery cell of any one of claims 3-7, wherein, The pressure relief groove is an annular groove, an inner diameter of the pressure relief groove is d, 0.5≤d / D≤0.

8.

9. The cylindrical battery cell of any one of claims 1-8, wherein, A thickness of the end cover is L3, a wall thickness of a side wall of the shell is L2, 0.3≤L2 / L3≤1.

2.

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

11. The cylindrical battery cell of claim 9 or 10, wherein, 0.3mm≤L2≤0.6mm; and / or, 0.3mm≤L3≤1mm.

12. The cylindrical battery cell of any one of claims 1-11, wherein, The end cover comprises: a body portion having a first surface facing the electrode assembly in the axial direction; a first protruding portion circumferentially arranged at an outer edge of the body portion and protruding from the first surface, the first protruding portion being at least partially inserted into the shell; an edge portion circumferentially arranged at an outer edge of the first protruding portion, the edge portion abutting an end of the shell where the opening is formed, the edge portion and the shell being welded to form the fusion portion.

13. The cylindrical battery cell of claim 12, wherein, The end cover has a contact interface in contact with the shell, the contact interface comprising a first interface extending from the fusion portion to the receiving space, the first interface being connected to a first position on a surface of the fusion portion; In the axial direction, the first protruding portion has a second surface facing the electrode assembly, a minimum distance between the first position and the second surface being L4, 2≤L4 / H≤20.

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

15. The cylindrical battery cell of any one of claims 12-14, wherein, The cylindrical battery cell further comprises a first current collecting member accommodated in the receiving space, the first current collecting member being arranged between the end cover and the electrode assembly in the axial direction, the electrode assembly having a first tab, the first current collecting member connecting the first tab and the first protruding portion.

16. The cylindrical battery cell of claim 15, wherein, The first protruding portion and the first current collecting member are welded, and a region of the end cover corresponding to the first protruding portion on a side of the end cover facing away from the electrode assembly is provided with a first groove.

17. The cylindrical battery cell of any one of claims 1-16, wherein, The end cover has a contact interface in contact with the case, 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 accommodation space, the second interface extends from the fusion portion to the outside of the cylindrical battery cell, the first interface is connected to a first position on the surface of the fusion portion, the second interface is connected to a second position on the surface of the fusion portion, 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 of any one of claims 1-16, wherein, The surface of the fusion portion includes a third surface connecting the outer surface of the end cover and the outer surface of the case. The end cover has a contact interface in contact with the case, the contact interface includes a first interface extending from the fusion portion to the accommodation space, the first interface is connected to a first position on the surface of the fusion portion, 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 comprising the cylindrical battery cell of any one of claims 1-18.

20. An electric device comprising the cylindrical battery cell of any one of claims 1-18 or the battery device of claim 19.

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