Battery cell, battery, and electrical device

Abstract

A battery cell (10), a battery (100), and an electrical device. The battery cell (10) comprises a housing (1) and an electrode assembly (2). The housing (1) is cylindrical, the housing (1) accommodates the electrode assembly (2), and the housing (1) comprises a side wall (13) disposed surrounding the electrode assembly (2). The side wall (13) is provided with a groove group (131), the groove group (131) comprising multiple grooves arranged at intervals along a circumferential direction of the side wall (13), the multiple grooves comprising at least one first groove (132), and the side wall (13) being configured to be capable of cracking along at least a portion of the first groove (132) when the battery cell (10) releases pressure. The multiple grooves further comprise at least one second groove (133), the minimum residual thickness of the second groove (133) being greater than the minimum residual thickness of the first groove (132). Disposing the second groove (133) on the side wall (13) enables the side wall (13) to release stress at the position where the second groove (133) is disposed, thereby alleviating deformation of the side wall (13) caused by stress release of the side wall at the first groove (132), effectively increasing the roundness of the side wall (13), and increasing assembly quality of the battery cell (10), thereby prolonging the service life of the battery cell (10).

Description

Battery cells, batteries and electrical equipment Technical Field

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

[0002] In recent years, new energy vehicles have experienced rapid development. Within the electric vehicle sector, power batteries, as the power source for electric vehicles, play an irreplaceable and important role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also growing. This increasing demand for batteries places higher demands on the reliability of battery cells.

[0003] In battery technology, not only the reliability of battery cells needs to be considered, but also the service life of battery cells. Therefore, how to improve the service life of battery cells is an urgent problem to be solved in battery technology.

[0004] Summary of the Invention

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

[0006] In a first aspect, an embodiment of the present application provides a battery cell, comprising a shell and an electrode assembly; the shell is cylindrical, accommodating the electrode assembly, and the shell includes a side wall arranged around the electrode assembly; the side wall is provided with a groove group, the groove group includes a plurality of grooves arranged at circumferential intervals along the side wall, the plurality of grooves include at least one first groove, and the side wall is configured to be able to crack along at least a portion of the first groove when the battery cell is depressurized; wherein the plurality of grooves also include at least one second groove, and the minimum residual thickness of the second groove is greater than the minimum residual thickness of the first groove.

[0007] In the above technical solution, the side wall of the shell is provided with a groove group, and the multiple grooves of the groove group include a first groove, so that the side wall can be cracked along at least a portion of the first groove when the battery cell is depressurized, thereby releasing the internal pressure of the battery cell, so that the side wall of the shell has a pressure relief function. The multiple grooves of the groove group also include a second groove, and the minimum residual thickness of the second groove is less than the minimum residual thickness of the first groove, so that the side wall is easy to crack along the first groove when the battery cell is depressurized, but not easy to crack along the second groove. The provision of the second groove on the side wall allows the side wall to release stress at the position where the second groove is provided, thereby alleviating the deformation of the side wall caused by the stress released by the first groove, which can effectively improve the roundness of the side wall, improve the assembly quality of the battery cell, and thus increase the service life of the battery cell.

[0008] In some embodiments, the first grooves and the second grooves are alternately arranged along the circumference of the sidewall. Each second groove can alleviate the sidewall deformation caused by the stress release of the two adjacent first grooves on both sides, thereby further improving the roundness of the sidewall.

[0009] In some embodiments, the slot pack includes multiple first and second grooves. Having multiple first grooves in the slot pack improves the pressure relief capability of the sidewall, enabling the sidewall to rupture along the multiple first grooves in the event of thermal runaway of a battery cell, thereby releasing pressure from within the battery cell at multiple locations on the sidewall. Having multiple second grooves in the slot pack allows stress relief at all locations where the multiple second grooves are located, further reducing deformation of the sidewall caused by the first grooves and improving the roundness of the sidewall.

[0010] In some embodiments, the sum of the number of first grooves and the number of second grooves in a groove group is N, where 2≤N≤20. This ensures that the sum of the number of first grooves and the number of second grooves in a groove group is within a reasonable range, reducing the risk of insufficient sidewall strength due to an excessive sum of the number of first grooves and the number of second grooves.

[0011] In some embodiments, 6≤N≤15. N≥6 ensures that there are a sufficient number of grooves on the sidewall, which is beneficial to improving the roundness of the sidewall; N≤15 further reduces the total number of first grooves and second grooves, which can further increase the strength of the sidewall.

[0012] In some embodiments, the number of first grooves and the number of second grooves in the groove group are equal. Half of the grooves in the groove group can be first grooves and the other half can be second grooves, which can take into account both the pressure relief capacity and the roundness of the side wall.

[0013] In some embodiments, the plurality of grooves in the groove group are evenly distributed on the sidewall along the circumference of the sidewall, so that the force applied to each groove when forming the sidewall is more uniform, and the roundness of the sidewall can be further improved.

[0014] In some embodiments, the sidewall is provided with multiple groove groups, which are spaced apart along the axial direction of the sidewall. This structure allows emissions from the housing to be discharged from the first groove area of ​​the multiple groove groups in the event of thermal runaway of the battery cell, thereby improving the pressure relief rate of the battery cell.

[0015] In some embodiments, the first groove has a first-opening section that preferentially cracks. The first groove includes a first groove section, a second groove section, and a third groove section. The second groove section connects the first and third groove sections, and at least a portion of the second groove section forms the first-opening section. In the event of thermal runaway of the battery cell, the sidewall preferentially cracks at the location of the first-opening section of the second groove section. The resulting crack can propagate along the first and third groove sections. After the sidewall cracks at the location of the first-opening section, it can quickly crack along the first and third groove sections, thereby shortening the time it takes for the sidewall to crack along the first groove and relieving pressure in a timely manner. This reduces the risk of fire or explosion in the event of thermal runaway of the battery cell, thereby effectively improving the reliability of the battery cell.

[0016] In some embodiments, the first, second, and third groove sections are sequentially connected to form a continuously arranged first groove. The midpoint of the first groove is located at the first opening section along the extension path of the first groove. Positioning the first opening section in the middle of the first groove can shorten the path difference between the sidewall cracking at the first opening section and the cracking toward both ends of the first groove, facilitating the synchronous cracking of the sidewall along the first and third groove sections. This further shortens the time it takes for the sidewall to crack along the first groove, thereby improving the timeliness of pressure relief in the battery cell.

[0017] In some embodiments, the midpoint of the second groove segment is located at the first-opening segment along its extension path. This can shorten the path difference between the sidewall cracking at the first-opening segment and the cracking path toward both ends of the second groove segment. This allows the sidewall to quickly crack along the second groove segment and, in turn, along the first and third groove segments in the event of thermal runaway of the battery cell, effectively shortening the time it takes for the sidewall to crack along the first groove.

[0018] In some embodiments, the minimum residual thickness of the first opening section is T1, the minimum residual thickness of the other areas of the first groove is T2, and the minimum residual thickness of the second groove is T3, where T1 < T2 and T1 < T3. This ensures that the strength of the residual portion of the other areas of the first groove and the residual portion of the second groove are both greater than the strength of the residual portion of the first opening section, allowing the sidewall to preferentially cleave in the first opening section when the battery cell experiences thermal runaway. Furthermore, the sidewall can cleave along the first groove when the battery cell experiences thermal runaway, but is less likely to cleave along the second groove.

[0019] In some embodiments, |T3-T2|≤0.1 mm. This ensures that the depth of the second groove does not differ significantly from the depth of other areas of the first groove, thereby reducing the difference in material extrusion between the first and second grooves during machining, reducing deformation of the sidewall, and improving the roundness of the sidewall.

[0020] In some embodiments, the minimum residual thickness of the first-opening section is T1, the wall thickness of the sidewall is D, and 0.04 ≤ T1 / D ≤ 0.9. T1 / D ≥ 0.04 ensures that the minimum residual thickness of the first-opening section accounts for a moderate proportion of the total wall thickness of the sidewall, ensuring sufficient strength of the residual portion of the first-opening section. This reduces the risk of premature cracking of the sidewall along the first-opening section during long-term cycling of the battery cell, thereby increasing the service life of the battery cell. T1 / D ≤ 0.9 ensures that the minimum residual thickness of the first-opening section accounts for a moderate proportion of the total wall thickness of the sidewall, enabling the sidewall to crack more promptly along the first-opening section in the event of thermal runaway of the battery cell, thereby shortening the time it takes for the sidewall to crack along the first groove and reducing the risk of fire or explosion of the battery cell.

[0021] In some embodiments, 0.1≤T1 / D≤0.5. T1 / D≥0.1 further increases the proportion of the minimum residual thickness of the first-opening section in the wall thickness of the sidewall, further reducing the risk of premature cracking of the sidewall along the first-opening section during long-term cycling of the battery cell. T1 / D≤0.5 further reduces the proportion of the minimum residual thickness of the first-opening section in the wall thickness of the sidewall, further reducing the risk of fire or explosion of the battery cell.

[0022] In some embodiments, along the extension path of the second groove segment, the groove length of the first-opening segment is L, 0.2 mm ≤ L ≤ 10 mm. L ≥ 0.2 mm prevents the groove length of the first-opening segment from being too small, thereby reducing the difficulty of machining the first-opening segment. L ≤ 10 mm prevents the groove length of the first-opening segment from being too large, thereby enabling precise control of the detonation position on the side wall and improving the accuracy of the detonation position.

[0023] In some embodiments, 1 mm ≤ L ≤ 6 mm. If L ≥ 1 mm, the groove length of the first-opening section is further increased, thereby further reducing the difficulty of processing the first-opening section; if L ≤ 6 mm, the groove length of the first-opening section is further reduced, thereby further improving the accuracy of the detonation position of the side wall.

[0024] In some embodiments, the first, second, and third groove sections are sequentially connected to form a continuously arranged first groove, with the first and third groove sections disposed opposite each other. This allows the first groove to be U-shaped, resulting in a simple structure. Furthermore, the first, second, and third groove sections can define a predetermined pressure relief area. When the battery cell releases pressure, the predetermined pressure relief area can be rapidly opened outward by flipping, thereby increasing the pressure relief area of ​​the battery cell and effectively improving the pressure relief rate of the battery cell.

[0025] In some embodiments, the first and third groove sections are smoothly connected to the second groove section. On the one hand, this allows the sidewall to smoothly split along the first and third groove sections after splitting along the second groove section, shortening the time it takes for the sidewall to split along the first groove and allowing the predetermined pressure relief area to flip toward the outside of the housing more smoothly. On the other hand, this effectively reduces the stress concentration factor at the connection between the first and second groove sections and at the connection between the third and second groove sections, thereby improving the fatigue strength of the sidewall and effectively increasing the service life of the battery cell.

[0026] In some embodiments, the second slot segment includes a first connecting segment, a second connecting segment, and a first-opening segment, wherein the first connecting segment connects the first-opening segment and the first slot segment, and the second connecting segment connects the first-opening segment and the third slot segment; wherein the minimum residual thickness of the first connecting segment, the minimum residual thickness of the second connecting segment, the minimum residual thickness of the first slot segment, and the minimum residual thickness of the third slot segment are all greater than the minimum residual thickness of the first-opening segment. The first-opening segment is positioned in the middle of the second slot segment, so that after the sidewall cracks at the first-opening segment, it can quickly crack along the first connecting segment and the second connecting segment located at both ends of the first-opening segment, shortening the time it takes for the sidewall to crack along the second slot segment, thereby enabling the sidewall to quickly crack along the first and third slot segments.

[0027] In some embodiments, the minimum residual thickness of the first connecting segment is equal to the minimum residual thickness of the first groove segment; and / or, the minimum residual thickness of the second connecting segment is equal to the minimum residual thickness of the third groove segment; and / or, the minimum residual thickness of the first connecting segment is equal to the minimum residual thickness of the second connecting segment; and / or, the minimum residual thickness of the first groove segment is equal to the minimum residual thickness of the third groove segment. This effectively reduces the difficulty of forming the first groove.

[0028] In some embodiments, the extension trajectory of the first slot segment lies within a first plane, and the angle between the centerline of the sidewall and the first plane is α1, where 30°≤α1≤90°. Keeping the angle between the centerline of the sidewall and the first plane within a reasonable range can reduce the risk of the sidewall tearing due to continued cracking along the extension of the first slot segment after cracking along the first slot segment.

[0029] In some embodiments, the extension trajectory of the third groove segment lies within the second plane, and the angle between the centerline of the sidewall and the second plane is α2, where 30°≤α2≤90°. Keeping the angle between the centerline of the sidewall and the second plane within a reasonable range can reduce the risk of the sidewall tearing due to continued cracking along the extension of the third groove segment after cracking along the third groove segment.

[0030] In some embodiments, the first groove has a width of W1, the second groove has a width of W2, and |W2-W1| ≤ 0.1 mm. This allows the width of the second groove to be less than the width of the first groove, thereby minimizing the difference in material extrusion during machining of the first and second grooves, reducing deformation of the sidewall, and improving the roundness of the sidewall.

[0031] In some embodiments, the first groove is disposed on the outer surface of the sidewall; and / or the second groove is disposed on the outer surface of the sidewall. If the first groove is disposed on the outer surface of the sidewall, the first groove can be machined on the outer surface of the sidewall, reducing the difficulty of machining the first groove; if the second groove is disposed on the outer surface of the sidewall, the second groove can be machined on the outer surface of the sidewall, reducing the difficulty of machining the second groove.

[0032] In some embodiments, the first groove is a groove extending along a non-enclosed trajectory; and / or, the second groove is a groove extending along a non-enclosed trajectory. If the first groove is a groove extending along a non-enclosed trajectory, the sidewall has better fatigue resistance, reducing the risk of the sidewall prematurely cracking along the first groove during long-term cycling of the battery cell. In addition, after the sidewall cracks along the first groove, the open portion of the sidewall is less likely to splash. If the second groove is a groove extending along a non-enclosed trajectory, the sidewall has better impact resistance, reducing the risk of the sidewall being impacted near the second groove and cracking along the second groove.

[0033] In some embodiments, the sidewalls have openings formed at opposite ends along their axial direction. The housing further includes two end caps, each of which seals the openings at each end of the sidewalls. This creates a hollow structure with openings at both ends, allowing the electrode assembly to be assembled into the sidewalls through either opening. This reduces the difficulty of battery cell assembly and improves the quality of battery cell assembly. This structure also makes sidewall molding easier, allowing for a longer sidewall length (axial dimension), which in turn increases the battery cell's capacity.

[0034] In some embodiments, the housing includes a shell and an end cap. The shell includes a side wall and a bottom wall. Along the axial direction of the side wall, one end of the side wall is connected to the bottom wall, and the other end of the side wall forms an opening. The end cap seals the opening. The shell is a hollow structure with an opening at one end. Only one end cap is required to mate with the shell in a battery cell, simplifying the structure of the battery cell.

[0035] In a second aspect, an embodiment of the present application provides a battery, comprising a battery cell provided by any embodiment of the first aspect.

[0036] In a third aspect, the present application further provides an electrical device, comprising a battery cell provided by any one embodiment of the first aspect, wherein the battery cell is used to provide electrical energy to the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0038] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0039] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0040] FIG3 is an assembly diagram of a battery cell provided in some embodiments of the present application;

[0041] FIG4 is an exploded view of the battery cell shown in FIG3 ;

[0042] FIG5 is a schematic structural diagram of the housing shown in FIG4 ;

[0043] FIG6 is a partial view of the housing shown in FIG5 ;

[0044] FIG7 is a cross-sectional view taken along line AA of the housing shown in FIG6 ;

[0045] FIG8 is a partial enlarged view of point C in FIG7;

[0046] FIG9 is a partial enlarged view of point E in FIG7 ;

[0047] FIG10 is a BB cross-sectional view of the housing shown in FIG6 ;

[0048] FIG11 is a partial enlarged view of point F in FIG11 ;

[0049] FIG12 is an exploded view of a battery cell provided in some embodiments of the present application.

[0050] Icons: 1-shell; 11-shell; 12-end cover; 13-side wall; 131-slot group; 132-first groove; 1321-first slot section; 1322-second slot section; 1322a-first opening section; 1322b-first connecting section; 1322c-second connecting section; 1323-third slot section; 133-second groove; 134-predetermined pressure relief area; 135-outer surface; 136-inner surface; 14-bottom wall; 2-electrode assembly; 21-ear; 3-electrode terminal; 4-current collecting member; 10-battery cell; 20-casing; 201-first part; 202-second part; 100-battery; 200-controller; 300-motor; 1000-vehicle; O-centerline; U-first plane; V-second plane; X-axial direction; Y-circumferential direction. DETAILED DESCRIPTION

[0051] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0052] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0053] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0054] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0055] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0056] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0057] The term "plurality" used in this application refers to two or more (including two).

[0058] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0059] Battery cells include but are not limited to lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0060] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process, active ions (such as lithium ions) move back and forth between the positive and negative electrodes. A separator, placed between the positive and negative electrodes, reduces the risk of short circuits while allowing active ions to pass through.

[0061] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0062] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0063] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0064] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as 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 NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.

[0065] In some embodiments, a positive electrode may utilize a metal foam. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or the like. When a metal foam is used as the positive electrode, the surface of the metal foam may or may not include a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled or / and deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0066] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0067] As an example, the negative electrode current collector may be a metal foil, a metal foam, or a composite current collector. For example, the metal foil may be silver-surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium. The metal foam may be nickel foam, copper foam, aluminum foam, or alloy foam. The composite current collector may include a polymer base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0068] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0069] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0070] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0071] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0072] In some embodiments, the separator is a separator membrane, which can be any known porous separator membrane with good chemical and mechanical stability.

[0073] As an example, the separator can be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. In the case of a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0074] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0075] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel, or solid. Liquid electrolytes include an electrolyte salt and a solvent.

[0076] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0077] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent may also be an ether solvent. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0078] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0079] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0080] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, or the like.

[0081] As an example, the inorganic solid electrolyte may include an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0082] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0083] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0084] In some embodiments, the electrode assembly is a laminate structure.

[0085] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0086] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0087] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0088] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0089] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0090] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0091] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0092] In some embodiments, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0093] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. Prismatic battery cells include square-shell battery cells, blade-shaped battery cells, and polygonal prismatic batteries. Polygonal prismatic batteries are, for example, hexagonal prismatic batteries.

[0094] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0095] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0096] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0097] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

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

[0099] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery reliability must also be considered.

[0100] In order to improve the reliability of the battery cell, a pressure relief structure can generally be provided in the battery cell. When the battery cell experiences thermal runaway, the pressure inside the battery cell can be released through the pressure relief structure.

[0101] For general cylindrical battery cells, the pressure relief structure is set on the end cover. For example, a pressure relief groove is set on the end cover, and the pressure is relieved by the end cover rupturing at the position of the pressure relief groove. During actual use, the pressure relief groove on the end cover is easily blocked by other components, resulting in untimely pressure relief.

[0102] To reduce the risk of the pressure relief groove being blocked by other components, the pressure relief groove can be placed on the side wall of the battery cell housing. Because battery cells are cylindrical, even if multiple battery cells are arranged in multiple rows and columns, the pressure relief groove on the side wall is unlikely to be blocked by other battery cells, allowing normal pressure relief in the event of thermal runaway. When the pressure relief groove is machined on the side wall, the side wall will be subjected to the forming force of the processing tool, causing the side wall to deform and affecting the roundness of the side wall.

[0103] To improve the roundness of the sidewall, a central shaft can be inserted into the sidewall before forming the pressure relief groove. The central shaft provides support for the sidewall, thereby reducing the risk of deformation during the pressure relief groove formation. However, after the central shaft is removed from the sidewall, residual stress remains in the sidewall where the pressure relief groove is located. As the residual stress is released, the sidewall will deform, resulting in a decrease in the roundness of the sidewall, affecting the assembly quality of the battery cell and, in turn, the service life of the battery cell.

[0104] In order to effectively improve the service life of battery cells, an embodiment of the present application provides a cylindrical battery cell, which is provided by arranging a groove group on the side wall of the shell, and the groove group includes a plurality of grooves arranged at circumferential intervals along the side wall, and the plurality of grooves include at least one first groove (pressure relief groove) and at least one second groove, and the minimum residual thickness of the second groove is greater than the minimum residual thickness of the first groove.

[0105] In such a battery cell, the multiple grooves in the slot assembly also include a second groove. The minimum residual thickness of the second groove is less than that of the first groove. This makes it easier for the sidewall to crack along the first groove when the battery cell releases pressure, but less likely to crack along the second groove. This makes the first groove a true pressure relief groove and the second groove a false pressure relief groove. The provision of the second groove on the sidewall allows stress to be released at the location where the second groove is provided, thereby alleviating deformation of the sidewall caused by stress release in the first groove. This can effectively improve the roundness of the sidewall, enhance the assembly quality of the battery cell, and thus increase the service life of the battery cell.

[0106] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0107] Electrically powered equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools. Vehicles can be fuel-powered, gas-powered, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles. Spacecraft include aircraft, rockets, space shuttles, and spacecraft. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

[0108] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0109] Please refer to Figure 1, which is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application. A battery 100 is disposed within vehicle 1000. Battery 100 can be located at the bottom, front, or rear of vehicle 1000. Battery 100 can be used to power vehicle 1000, for example, as an operating power source for vehicle 1000.

[0110] The vehicle 1000 may further include a controller 200 and a motor 300 . The controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0111] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0112] Please refer to Figure 2, which is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a battery cell 10 and a housing 20, wherein the battery cell 10 is accommodated in the housing 20.

[0113] The housing 20 is a component that houses the battery cells 10 and provides a storage space for the battery cells 10. The housing 20 can have various structures. In some embodiments, the housing 20 can include a first portion 201 and a second portion 202, which overlap to define a storage space for the battery cells 10. The first portion 201 and the second portion 202 can have various shapes, such as a rectangular parallelepiped or a cylindrical shape. The first portion 201 can be a hollow structure with one side open, and the second portion 202 can be a hollow structure with one side open. The open side of the second portion 202 overlaps the open side of the first portion 201, thereby forming the housing 20 with a storage space. Alternatively, the first portion 201 can be a hollow structure with one side open, and the second portion 202 can be a plate-like structure. The second portion 202 overlaps the open side of the first portion 201, thereby forming the housing 20 with a storage space. The first portion 201 and the second portion 202 can be sealed by a sealing element, which can be a sealing ring, sealant, etc.

[0114] In the battery 100, there can be one or more battery cells 10. If there are multiple battery cells 10, the multiple battery cells 10 can be connected in series, parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 10. Multiple battery cells 10 can be connected in series, parallel, or in a hybrid connection to form a battery module, which can then be connected in series, parallel, or in a hybrid connection to form a single unit and housed within the housing 20. Alternatively, all battery cells 10 can be directly connected in series, parallel, or in a hybrid connection, and then the entire unit formed by all battery cells 10 can be housed within the housing 20.

[0115] 3 and 4 , FIG3 is an assembly diagram of a battery cell 10 according to some embodiments of the present application; FIG4 is an exploded diagram of the battery cell 10 shown in FIG3 . The battery cell 10 may include a housing 1 and an electrode assembly 2 , wherein the electrode assembly 2 is accommodated in the housing 1 .

[0116] In some embodiments, the housing 1 may include a shell 11 and an end cover 12 , wherein the shell 11 has an opening and the end cover 12 closes the opening of the shell 11 .

[0117] The housing 11 is a component for accommodating the electrode assembly 2. The housing 11 can be a hollow structure with an opening at one end, or a hollow structure with openings at opposite ends. The housing 11 can have various shapes, such as a cylinder or a rectangular parallelepiped. The housing 11 can be made of various materials, such as copper, iron, aluminum, steel, and aluminum alloys.

[0118] The end cap 12 is a component that closes the opening of the shell 11 to isolate the internal environment of the battery cell 10 from the external environment. The end cap 12 and the shell 11 together define a storage space for accommodating the electrode assembly 2, electrolyte and other components. The end cap 12 can be connected to the shell 11 by welding or rolling to close the opening of the shell 11. The shape of the end cap 12 can be adapted to the shape of the shell 1. For example, the shell 11 is a rectangular parallelepiped structure, and the end cap 12 is a rectangular plate structure adapted to the shell 1. For another example, the shell 11 is cylindrical, and the end cap 12 is a circular plate structure adapted to the shell 11. The material of the end cap 12 can also be a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the end cap 12 and the shell 11 can be the same or different.

[0119] In an embodiment where the housing 11 is open at one end, one end cap 12 may be provided. In an embodiment where the housing 11 is open at two opposite ends, two end caps 12 may be provided, each of which closes the two openings of the housing 11, and the two end caps 12 and the housing 11 together define a receiving space.

[0120] In some embodiments, the battery cell 10 may further include an electrode terminal 3, which is disposed on the outer casing 1. The electrode terminal 3 is used to electrically connect to the tab 21 of the electrode assembly 2 to input or output electrical energy from the battery cell 10. The electrode terminal 3 may be disposed on the shell 11 of the outer casing 1 or on the end cap 12 of the outer casing 1. The electrode terminal 3 and the tab 21 may be directly connected, for example, by welding the electrode terminal 3 to the tab 21. The electrode terminal 3 and the tab 21 may also be indirectly connected, for example, by indirectly connecting the electrode terminal 3 and the tab 21 through a current collecting member 4. The current collecting member 4 may be a metal conductor, such as copper, iron, aluminum, steel, or an aluminum alloy.

[0121] As an example, in the embodiment shown in Figures 3 and 4, openings are formed at opposite ends of the housing 11. Two end caps 12 are provided in the outer shell 1, and the two end caps 12 respectively seal the two openings of the housing 11. Electrode terminals 3 are provided on each end cap 12, and tabs 21 are formed at opposite ends of the electrode assembly 2. The tab 21 at one end of the electrode assembly 2 is a positive tab, and the tab 21 at the other end is a negative tab. The electrode terminal 3 on one end cap 12 is connected to the positive tab via a current collecting member 4, and the electrode terminal 3 on the other end cap 12 is connected to the negative tab via another current collecting member 4.

[0122] Continuing with reference to Figures 3 and 4, an embodiment of the present application provides a battery cell 10 comprising a housing 1 and an electrode assembly 2. The housing 1 is cylindrical, and the electrode assembly 2 is accommodated within the housing 1. The housing 1 comprises a sidewall 13 disposed around the electrode assembly 2. The sidewall 13 is provided with a groove group 131. The groove group 131 comprises a plurality of grooves spaced apart along the circumference Y of the sidewall 13. The plurality of grooves comprises at least one first groove 132. The sidewall 13 is configured to rupture along at least a portion of the first groove 132 when the battery cell 10 is depressurized. The plurality of grooves further comprises at least one second groove 133. The minimum residual thickness of the second groove 133 is greater than the minimum residual thickness of the first groove 132.

[0123] The outer shell 1 is cylindrical, making the battery cell 10 a cylindrical battery cell. It is understood that the overall structure formed by the outer shell 1 and the end cap 12 is cylindrical. It should be noted that in the embodiments of the present application, the outer shell 1 being cylindrical does not limit the outer shell 1 to a completely regular cylindrical shape. The outer shell 1 can also be an irregular cylindrical shape. For example, the outer shell 1 can be partially formed with a convex portion or a concave portion, so that the outer shell 1 is generally cylindrical.

[0124] The electrode assembly 2 may be a wound structure. The electrode assembly 2 may be formed by winding a positive electrode sheet, a separator, and a negative electrode sheet. The electrode assembly 2 may be cylindrical.

[0125] The sidewall 13 is the portion of the housing 1 surrounding the electrode assembly 2. It can be that at least a portion of the shell 11 within the housing 1 constitutes the sidewall 13. The sidewall 13 is also cylindrical, with a circular cross-section perpendicular to the axial direction X of the sidewall 13. In embodiments where the shell 11 is a hollow structure with an opening at one end, the portion of the shell 11 surrounding the electrode assembly 2 constitutes the sidewall 13. It will be understood that the sidewall 13 is merely a portion of the shell 11. In embodiments where the shell 11 is a hollow structure with openings at opposite ends, the sidewall 13 constitutes the shell 11.

[0126] The sidewall 13 may include one or more groove groups 131. The grooves in the groove group 131 are spaced apart along the circumferential direction Y of the sidewall 13, such that adjacent grooves in the groove group 131 are spaced a certain distance apart along the circumferential direction Y of the sidewall 13. The groove group 131 may include two, three, four, five, six, or more grooves. The grooves in the groove group 131 may be evenly distributed along the circumferential direction Y of the sidewall 13, such that all first grooves 132 and all second grooves 133 in the groove group 131 are evenly distributed along the circumferential direction Y of the sidewall 13. Alternatively, the grooves in the groove group 131 may be unevenly distributed along the circumferential direction Y of the sidewall 13.

[0127] The plurality of grooves includes at least one first groove 132 and at least one second groove 133. That is, among the plurality of grooves in the groove group 131, at least one groove is a first groove 132 and at least one groove is a second groove 133. In the groove group 131, there can be one, two, three, four, or more first grooves 132, and there can be one, two, three, four, or more second grooves 133. In the groove group 131, the number of first grooves 132 can be equal to the number of second grooves 133, or the number of first grooves 132 can be greater than the number of second grooves 133, or the number of second grooves 133 can be greater than the number of first grooves 132. The sum of the number of first grooves 132 and the number of first grooves 132 can be an even number or an odd number. In the slot group 131, along the circumferential direction Y of the side wall 13, at least two first grooves 132 may be adjacently arranged, and at least two second grooves 133 may be adjacently arranged. For example, in a slot group 131 with three first grooves 132 and three second grooves 133, three first grooves 132 may be adjacently arranged, and three second grooves 133 may be adjacently arranged. In the slot group 131, along the circumferential direction Y of the side wall 13, one or more second grooves 133 may be arranged between two adjacent first grooves 132, and one or more first grooves 132 may be arranged between two adjacent second grooves 133.

[0128] The first groove 132 is a pressure relief groove provided on the sidewall 13. When the battery cell 10 releases pressure, the sidewall 13 can rupture along at least a portion of the first groove 132 to release the pressure within the battery cell 10. In other words, when the battery cell 10 releases pressure, the sidewall 13 can rupture along a portion of the first groove 132, or it can rupture along the entire first groove 132. The first groove 132 can extend along a non-enclosed path or a closed path.

[0129] The first groove 132 can be formed in a variety of ways, such as stamping, milling, etc. The first groove 132 can be provided on the outer surface 135 of the side wall 13 (not shown in Figures 3 and 4), or on the inner surface 136 of the side wall 13 (not shown in Figures 3 and 4). The first groove 132 can be a groove extending along a straight line, that is, the first groove 132 is a straight groove; the first groove 132 can also be a groove extending along a non-linear path, for example, the first groove 132 is a circular arc groove, an annular groove, a U-shaped groove, an X-shaped groove, a Y-shaped groove, a V-shaped groove, an H-shaped groove, etc.

[0130] The shape of the second groove 133 can be the same as that of the first groove 132, for example, both the second groove 133 and the first groove 132 are U-shaped grooves; the shape of the second groove 133 can also be different from that of the first groove 132, for example, one of the first groove 132 and the second groove 133 is a U-shaped groove and the other is an H-shaped groove. The volume of the second groove 133 can be equal to or different from the volume of the first groove 132. As an example, the volume of the first groove 132 is V1, the volume of the second groove 133 is V2, and the volume of the larger one of the first groove 132 and the second groove 133 is V3, 0≤|V1-V2| / V3≤0.3, thereby reducing the difference in the amount of extrusion when forming the first groove 132 and the second groove 133, which is beneficial to improving the roundness of the side wall 13. Among them, |V1-V2| / V3 can take any point value among 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, etc., or a range of values ​​between any two points.

[0131] The second groove 133 can be formed in a variety of ways, such as by stamping, milling, etc. The second groove 133 and the first groove 132 can be disposed on the same surface of the sidewall 13. For example, the second groove 133 and the first groove 132 can both be disposed on the outer surface 135 of the sidewall 13. For another example, the second groove 133 and the first groove 132 can both be disposed on the inner surface 136 of the sidewall 13. The second groove 133 and the first groove 132 can also be disposed on different surfaces of the sidewall 13. For example, one of the second groove 133 and the first groove 132 can be disposed on the outer surface 135 of the sidewall 13, and the other can be disposed on the inner surface 136 of the sidewall 13. The second groove 133 can be a groove extending along a non-closed trajectory; the second groove 133 can also be a groove extending along a closed trajectory.

[0132] The minimum residual thickness of the second groove 133 is greater than that of the first groove 132. Therefore, the second groove 133 has the greater minimum residual thickness within the groove group 131, while the first groove 132 has the smaller minimum residual thickness. In the event of thermal runaway of the battery cell 10, the sidewall 13 is more likely to crack at the first groove 132 than at the second groove 133. Therefore, the first groove 132 is a true pressure relief groove, while the second groove 133 is a false pressure relief groove. The minimum residual thickness of the first groove 132 is the minimum thickness of the remaining portion of the first groove 132, which can be the bottom wall of the first groove 132. The minimum residual thickness of the second groove 133 is the minimum thickness of the remaining portion of the second groove 133, which can be the bottom wall of the second groove 133. The minimum residual thickness of the first groove 132 can be measured at the thinnest point of the remaining portion of the first groove 132, while the minimum residual thickness of the second groove 133 can be measured at the thinnest point of the remaining portion of the second groove 133.

[0133] In the embodiment of the present application, the sidewall 13 of the housing 1 is provided with a groove group 131. The multiple grooves of the groove group 131 include a first groove 132, which enables the sidewall 13 to rupture along at least a portion of the first groove 132 when the battery cell 10 releases pressure, thereby releasing the internal pressure of the battery cell 10 and providing the sidewall 13 of the housing 1 with a pressure relief function. The multiple grooves of the groove group 131 also include a second groove 133. The minimum residual thickness of the second groove 133 is less than the minimum residual thickness of the first groove 132. This makes it easier for the sidewall 13 to rupture along the first groove 132 when the battery cell 10 releases pressure, but less likely to rupture along the second groove 133. This makes the first groove 132 a true pressure relief groove and the second groove 133 a false pressure relief groove. The setting of the second groove 133 on the side wall 13 allows the side wall 13 to release stress at the position where the second groove 133 is set, thereby alleviating the deformation of the side wall 13 caused by the stress released by the side wall 13 in the first groove 132, and can effectively improve the roundness of the side wall 13, improve the assembly quality of the battery cell 10, and thus increase the service life of the battery cell 10.

[0134] Taking the welding of the end cover 12 and the side wall 13 in the shell 1 as an example, by providing the second groove 133 to improve the roundness of the side wall 13, the welding quality of the end cover 12 and the side wall 13 can be effectively improved, and the connection strength between the end cover 12 and the side wall 13 can be improved, thereby increasing the service life of the battery cell 10.

[0135] In some embodiments, along the circumferential direction Y of the sidewall 13 , the first grooves 132 and the second grooves 133 are alternately arranged.

[0136] In this embodiment, there can be one or more first grooves 132, and there can be one or more second grooves 133. Since the first grooves 132 and the second grooves 133 are alternately arranged along the circumferential direction Y of the side wall 13, the number of first grooves 132 and the number of second grooves 133 in the groove group 131 are equal.

[0137] As an example, in the embodiments shown in Figures 3 and 4, there are three first grooves 132 and three second grooves 133, and there are six grooves in the groove group 131. The grooves in the groove group 131 are arranged in the order of first groove 132-second groove 133-first groove 132-second groove 133-first groove 132-second groove 133 to achieve alternating arrangement of the first groove 132 and the second groove 133.

[0138] In this embodiment, the first grooves 132 and the second grooves 133 in the groove group 131 are alternately arranged along the circumferential direction Y of the side wall 13, so that each second groove 133 can alleviate the deformation of the side wall 13 caused by the release of stress of the two adjacent first grooves 132 on both sides, and can further improve the roundness of the side wall 13.

[0139] In some embodiments, there are multiple first grooves 132 and multiple second grooves 133 in the groove set 131 .

[0140] In this embodiment, the number of first grooves 132 in the groove group 131 may be two, three, four, or more, and the number of second grooves 133 may be two, three, four, or more. The number of first grooves 132 and the number of second grooves 133 in the groove group 131 may be equal or different.

[0141] In this embodiment, the slot group 131 includes multiple first grooves 132, which improve the pressure relief capability of the sidewall 13. This allows the sidewall 13 to rupture along the multiple first grooves 132 when a battery cell 10 experiences thermal runaway, thereby releasing pressure from within the battery cell 10 at multiple locations on the sidewall 13. The slot group 131 includes multiple second grooves 133, allowing stress relief at all locations where the multiple second grooves 133 are located. This further reduces deformation of the sidewall 13 caused by the first grooves 132 and improves the roundness of the sidewall 13.

[0142] In some embodiments, the sum of the number of first grooves 132 and the number of second grooves 133 in the groove set 131 is N, and 2≤N≤20.

[0143] N is an integer and can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20.

[0144] In this embodiment, the number of first grooves 132 and the number of second grooves 133 in the groove group 131 may be equal or unequal. If the number of first grooves 132 and the number of second grooves 133 in the groove group 131 are unequal, the number of first grooves 132 may be greater than the number of second grooves 133, or the number of second grooves 133 may be greater than the number of first grooves 132. Taking N=6 as an example, the number of first grooves 132 and second grooves 133 may be three, such that the number of first grooves 132 and second grooves 133 are equal; the number of first grooves 132 may be four and the number of second grooves 133 two, such that the number of first grooves 132 is greater than the number of second grooves 133; or the number of first grooves 132 may be two and the number of second grooves 133 is four, such that the number of second grooves 133 is greater than the number of first grooves 132.

[0145] In this embodiment, 2≤N≤20, so that the sum of the number of first grooves 132 and the number of second grooves 133 in the groove group 131 is within a reasonable range, reducing the risk of insufficient strength of the side wall 13 due to the sum of the number of first grooves 132 and the number of second grooves 133 being too large.

[0146] In some embodiments, 6≤N≤15.

[0147] In this embodiment, N can be 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15.

[0148] In this embodiment, N≥6, so that there are sufficient grooves on the side wall 13, which is beneficial to improving the roundness of the side wall 13; N≤15 further reduces the total number of the first grooves 132 and the second grooves 133, which can further increase the strength of the side wall 13.

[0149] In some embodiments, the number of first grooves 132 and the number of second grooves 133 in the groove set 131 are equal.

[0150] It can be understood that if there is one first groove 132 in the groove group 131, there is also one second groove 133 in the groove group 131; if there are two first grooves 132 in the groove group 131, there are also two second grooves 133 in the groove group 131; if there are three first grooves 132 in the groove group 131, there are also three second grooves 133 in the groove group 131; if there are four first grooves 132 in the groove group 131, there are also four second grooves 133 in the groove group 131; if there are five first grooves 132 in the groove group 131, there are also five second grooves 133 in the groove group 131; if there are six first grooves 132 in the groove group 131, there are also six second grooves 133 in the groove group 131.

[0151] In this embodiment, the number of first grooves 132 and the number of second grooves 133 in the groove group 131 are equal, so that half of the multiple grooves in the groove group 131 are first grooves 132 and the other half are second grooves 133. In this way, the pressure relief capacity and roundness of the side wall 13 can be taken into account.

[0152] In some embodiments, along the circumferential direction Y of the sidewall 13 , the plurality of grooves in the groove group 131 are evenly distributed on the sidewall 13 .

[0153] It is understood that in the groove group 131, the minimum distance between two adjacent grooves along the circumferential direction Y of the side wall 13 is equal. The number of grooves in the groove group 131 is N, and a groove can be provided every 360° / N along the circumferential direction Y of the side wall 13.

[0154] As an example, in the embodiments shown in Figures 3 and 4, there are six grooves in the groove group 131, three first grooves 132 and three second grooves 133, the first grooves 132 and the second grooves 133 are alternately arranged along the circumferential direction Y of the side wall 13, and the adjacent first grooves 132 and first grooves 132 are 60° apart.

[0155] In this embodiment, the multiple grooves in the groove group 131 are evenly distributed on the side wall 13 along the circumferential direction Y of the side wall 13, so that the force applied when forming each groove on the side wall 13 is more uniform, which can further improve the roundness of the side wall 13.

[0156] In some embodiments, the sidewall 13 is provided with a plurality of groove groups 131 , and the plurality of groove groups 131 are spaced apart along the axial direction X of the sidewall 13 .

[0157] The plurality of slot groups 131 are spaced apart along the axial direction X of the side wall 13 , that is, a certain distance is provided between two adjacent slot groups 131 along the axial direction X of the side wall 13 . The number of slot groups 131 on the side wall 13 may be two, three, four or more.

[0158] As an example, in the embodiments shown in Figures 3 and 4 , there are two slot groups 131 on the side wall 13, and the two slot groups 131 are spaced apart along the axial direction X of the side wall 13. In the event of thermal runaway of the battery cell 10, emissions at both ends of the battery cell 10 can be discharged separately through the two slot groups 131, and emissions in the middle of the battery cell 10 can be discharged simultaneously through the two slot groups 131.

[0159] In this embodiment, the sidewall 13 is provided with a plurality of slot groups 131, which are spaced apart along the axial direction X of the sidewall 13. This structure allows emissions from the interior of the housing 1 to be discharged from the regions of the first grooves 132 in the plurality of slot groups 131 when the battery cell 10 experiences thermal runaway, thereby improving the pressure relief rate of the battery cell 10. The emissions include, but are not limited to, electrolyte, dissolved or split positive and negative electrode sheets, separator fragments, high-temperature and high-pressure gases generated by the reaction, and flames.

[0160] In some embodiments, referring to Figures 5 and 6, Figure 5 is a schematic structural diagram of the housing 1 shown in Figure 4; Figure 6 is a partial view of the housing 1 shown in Figure 5. The first groove 132 has a first-opening section 1322a that preferentially breaks. The first groove 132 includes a first groove section 1321, a second groove section 1322, and a third groove section 1323. The second groove section 1322 connects the first groove section 1321 and the third groove section 1323, and at least a portion of the second groove section 1322 forms the first-opening section 1322a.

[0161] The first-opening section 1322a is the portion of the first groove 132 that cracks first. When the battery cell 10 is depressurized, the sidewall 13 at the first-opening section 1322a cracks before other areas of the sidewall 13 in the first groove 132. In other words, when the battery cell 10 experiences thermal runaway, the internal pressure of the battery cell 10 gradually increases, and the first-opening section 1322a cracks more easily than other areas of the first groove 132, causing the sidewall 13 to crack first. This may be because the remaining portion of the first-opening section 1322a is weaker than the remaining portions of the first groove 132, causing the sidewall 13 to crack first at the first-opening section 1322a.

[0162] The first, second, and third groove sections 1321, 1322, and 1323 are three sections of the first groove 132. The second groove section 1322 is the middle section of the first groove 132. The second groove section 1322 serves to connect the first and third groove sections 1321, 1323. A portion of the second groove section 1322 can be the first-opening section 1322a, or the entire second groove section 1322 can be the first-opening section 1322a. The first groove section 1321 can extend along a straight line, in which case the first groove section 1321 is parallel to the axial direction X of the side wall 13. The first groove section 1321 can also extend along an arcuate trajectory within a plane, for example, along the circumferential direction Y of the side wall 13. The first groove section 1321 can also extend along a spatial curved trajectory. The second slot segment 1322 can extend along a straight line, in which case the second slot segment 1322 is parallel to the axial direction X of the sidewall 13. Alternatively, the second slot segment 1322 can extend along an arcuate trajectory within a plane, for example, along the circumferential direction Y of the sidewall 13. Alternatively, the second slot segment 1322 can extend along a spatial curved trajectory. The third slot segment 1323 can extend along a straight line, in which case the third slot segment 1323 is parallel to the axial direction X of the sidewall 13. Alternatively, the third slot segment 1323 can extend along an arcuate trajectory within a plane, for example, along the circumferential direction Y of the sidewall 13. Alternatively, the third slot segment 1323 can extend along a spatial curved trajectory. The first groove section 1321, the second groove section 1322, and the third groove section 1323 may extend in the same direction. For example, the first groove section 1321, the second groove section 1322, and the third groove section 1323 may be collinear and extend along the axial direction X of the side wall 13. The residual thickness and / or groove depth of the first groove section 1321 and the third groove section 1323 may be different from those of the second groove section 1322 to distinguish the three. The first groove section 1321, the second groove section 1322, and the third groove section 1323 may extend in different directions. For example, the first groove section 1321, the second groove section 1322, and the third groove section 1323 may form a U-shaped or H-shaped structure, so that the first groove 132 is a U-shaped groove or an H-shaped groove.

[0163] In this embodiment, the first groove 132 includes a first groove section 1321, a second groove section 1322 and a third groove section 1323. The second groove section 1322 connects the first groove section 1321 and the third groove section 1323, and at least a portion of the second groove section 1322 forms a first opening section 1322a of the first groove 132. When the battery cell 10 thermally runs away, the side wall 13 is preferentially cracked at the position of the first opening section 1322a of the second groove section 1322, so that the second groove section 1322 located in the middle is relatively The first groove section 1321 and the third groove section 1323 crack first, and the cracks formed can spread along the first groove section 1321 and the third groove section 1323. After the side wall 13 cracks at the position of the first opening section 1322a, it can quickly crack along the first groove section 1321 and the third groove section 1323, thereby shortening the time it takes for the side wall 13 to crack along the first groove 132 and releasing pressure in time, reducing the risk of fire or explosion when the battery cell 10 thermally runs away, thereby effectively improving the reliability of the battery cell 10.

[0164] In some embodiments, please continue to refer to Figure 6, the first groove section 1321, the second groove section 1322 and the third groove section 1323 are connected in sequence to form a continuously arranged first groove 132. On the extension path of the first groove 132, the midpoint of the first groove 132 is located at the first opening section 1322a.

[0165] The first slot segment 1321, the second slot segment 1322, and the third slot segment 1323 are connected in sequence, i.e., one end of the first slot segment 1321 is connected to one end of the second slot segment 1322, and the other end of the second slot segment 1322 is connected to one end of the third slot segment 1323. The first slot segment 1321, the second slot segment 1322, and the third slot segment 1323 can form a U-shaped structure, a Z-shaped structure, or the like. Along the extension path of the first groove 132, the distance from the midpoint of the first groove 132 to the end of the first slot segment 1321 distal to the second slot segment 1322 is equal to the distance from the midpoint of the first groove 132 to the end of the third slot segment 1323 distal to the second slot segment 1322, and both are half the length of the first groove 132. Along the extension path of the first slot section 1321, the slot length of the first slot section 1321 is the first slot length; along the extension path of the second slot section 1322, the slot length of the second slot section 1322 is the second slot length; along the extension path of the third slot section 1323, the slot length of the third slot section 1323 is the third slot length. Along the extension path of the first groove 132, the slot length of the first groove 132 is equal to the sum of the first, second, and third slot lengths.

[0166] As an example, on the extension path of the first groove 132 , the midpoint of the first groove 132 is located between the two ends of the first opening section 1322 a .

[0167] In this embodiment, the midpoint of the first groove 132 is located at the first opening section 1322a, so that the first opening section 1322a is located in the middle area of ​​the first groove 132, which can shorten the path difference of the side wall 13 continuing to crack toward the two ends of the first groove 132 after cracking at the position of the first opening section 1322a, which is beneficial to the synchronous cracking of the side wall 13 along the first groove section 1321 and the third groove section 1323, further shortening the time it takes for the side wall 13 to crack along the first groove 132, and improving the timeliness of the pressure relief of the battery cell 10.

[0168] In some embodiments, on the extension path of the second slot segment 1322 , the midpoint of the second slot segment 1322 is located at the first opening segment 1322 a .

[0169] In this embodiment, the first slot segment 1321, the second slot segment 1322, and the third slot segment 1323 may be connected in sequence, for example, the first slot segment 1321, the second slot segment 1322, and the third slot segment 1323 form a U-shaped structure; or the connection position of the first slot segment 1321 and the second slot segment 1322 may deviate from the two ends of the first slot segment 1321, and the connection position of the third slot segment 1323 and the second slot segment 1322 may deviate from the two ends of the third slot segment 1323, for example, the first slot segment 1321, the second slot segment 1322, and the third slot segment 1323 form an H-shaped structure.

[0170] In the embodiment where the first slot segment 1321, the second slot segment 1322, and the third slot segment 1323 are connected in sequence, the midpoint of the second slot segment 1322 may or may not coincide with the midpoint of the first groove 132. It is understood that, along the extension path of the first groove 132, if the slot length of the first slot segment 1321 is equal to the slot length of the third slot segment 1323, the midpoint of the second slot segment 1322 coincides with the midpoint of the first groove 132; and if the slot length of the first slot segment 1321 is not equal to the slot length of the third slot segment 1323, the midpoint of the second slot segment 1322 does not coincide with the midpoint of the first groove 132.

[0171] As an example, in the embodiment shown in Figure 6, the first slot segment 1321, the second slot segment 1322 and the third slot segment 1323 are connected in sequence. On the extension path of the first groove 132, the slot length of the first slot segment 1321 is equal to the slot length of the third slot segment 1323, and the midpoint of the second slot segment 1322 is located between the two ends of the first opening segment 1322a.

[0172] In this embodiment, the midpoint of the second groove section 1322 is located at the first opening section 1322a, which can shorten the path difference of the side wall 13 continuing to crack toward the two ends of the second groove section 1322 after cracking at the position of the first opening section 1322a, so that the side wall 13 can quickly crack along the second groove section 1322 when the battery cell 10 thermally runs away, and then the side wall 13 can quickly crack along the first groove section 1321 and the third groove section 1323, which can effectively shorten the time it takes for the side wall 13 to crack along the first groove 132.

[0173] In some embodiments, referring to Figures 7-11, Figure 7 is a cross-sectional view taken along line AA of the housing 1 shown in Figure 6; Figure 8 is a partial enlarged view of point C in Figure 7; Figure 9 is a partial enlarged view of point E in Figure 7; Figure 10 is a cross-sectional view taken along line BB of the housing 1 shown in Figure 6; and Figure 11 is a partial enlarged view of point F in Figure 11. The minimum residual thickness of the first opening section 1322a is T1, the minimum residual thickness of the remaining areas of the first groove 132 is T2, and the minimum residual thickness of the second groove 133 is T3, where T1 < T2 and T1 < T3.

[0174] In this embodiment, T2 may be equal to T3, T2 may be less than T3, or T2 may be greater than T3.

[0175] The minimum residual thickness of the first opening section 1322a is the minimum residual thickness of the first groove 132. The minimum residual thickness of the first opening section 1322a is the minimum thickness of the remaining portion of the first opening section 1322a. The minimum thickness of the remaining portion of the first opening section 1322a can be measured at the thinnest location of the remaining portion of the first opening section 1322a. The remaining portion of the first opening section 1322a can form the bottom wall of the groove of the first opening section 1322a. The minimum residual thickness of the remaining portion of the first groove 132 is the minimum thickness of the remaining portion of the first groove 132. The minimum thickness of the remaining portion of the first groove 132 can be measured at the thinnest location of the remaining portion of the first groove 132. The remaining portion of the first groove 132 can form the bottom wall of the remaining portion of the first groove 132. The thickness of the remaining portion of the first opening section 1322a can be uniform or uneven; the thickness of the remaining portion of the other regions of the first groove 132 can be uniform or uneven.

[0176] As an example, the maximum residual thickness of the first opening section 1322a is also smaller than the minimum residual thickness of other areas of the first groove 132, so that the maximum thickness of the residual part of the first opening section 1322a is smaller than the minimum thickness of the residual part of other areas of the first groove 132, so that the residual thickness of the first opening section 1322a is smaller than the residual thickness of other areas of the first groove 132.

[0177] The other regions of the first groove 132 are the remaining portion of the first groove 132 excluding the first opening section 1322 a , and include a first groove section 1321 and a third groove section 1323 . In an embodiment in which the entire second slot segment 1322 forms the first-opening segment 1322a, the first slot segment 1321 and the third slot segment 1323 may constitute other areas of the first groove 132, and the minimum residual thickness of the first slot segment 1321 and the minimum residual thickness of the third slot segment 1323 is the minimum residual thickness of other areas of the first groove 132; in an embodiment in which only a part of the second slot segment 1322 forms the first-opening segment 1322a, the other part of the second slot segment 1322, the first slot segment 1321 and the third slot segment 1323 may constitute other areas of the first groove 132, and the minimum residual thickness of the other part of the second slot segment 1322, the minimum residual thickness of the first slot segment 1321 and the minimum residual thickness of the third slot segment 1323 is the minimum residual thickness of other areas of the first groove 132.

[0178] As an example, the maximum groove depth of the first opening section 1322a is greater than the maximum groove depth of other areas of the first groove 132, and the sum of the maximum groove depth of the first opening section 1322a and the minimum residual thickness of the first opening section 1322a and the sum of the maximum groove depth of other areas of the first groove 132 and the minimum residual thickness of other areas of the first groove 132 are all equal to the wall thickness of the side wall 13.

[0179] In this embodiment, T1<T2, T1<T3, so that the strength of the residual portion of the other areas of the first groove 132 and the strength of the residual portion of the second groove 133 are both greater than the strength of the residual portion of the first opening section 1322a, so that the side wall 13 can be preferentially cracked in the first opening section 1322a when the battery cell 10 thermally runs away, so that the side wall 13 can be cracked along the first groove 132 when the battery cell 10 thermally runs away, but it is difficult to crack along the second groove 133.

[0180] In other embodiments, other methods can be used to ensure that the side wall 13 is preferentially cracked in the first-opening section 1322a when the battery cell 10 thermally runs away. For example, the minimum residual thickness of the first-opening section 1322a is equal to the minimum residual thickness of other areas of the first groove 132. At least part of the residual portion of the second groove section 1322 can be heat-treated to reduce the strength of the portion to form the corresponding first-opening section 1322a, so that the strength of the residual portion of the first-opening section 1322a is less than the strength of the residual thickness of other areas of the first groove 132.

[0181] In some embodiments, |T3-T2|≤0.1 mm.

[0182] |T3-T2| can take any point value among 0mm, 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, or a range between any two of them.

[0183] In this embodiment, |T3-T2|≤0.1mm, so that the groove depth of the second groove 133 does not differ too much from the groove depth of other areas of the first groove 132, which is beneficial to reducing the difference in the extrusion amount between the first groove 132 and the second groove 133 when processing the two, reducing the deformation of the side wall 13, and improving the roundness of the side wall 13.

[0184] In some embodiments, referring to FIG. 8 , the minimum residual thickness of the first-opened section 1322 a is T1 , the thickness of the sidewall 13 is D, and 0.04≤T1 / D≤0.9.

[0185] T1 / D can be any one of 0.04, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or any range between two of them.

[0186] T1 / D≥0.04, so that the minimum residual thickness of the first-opening section 1322a accounts for not too small a proportion of the wall thickness of the side wall 13, so that the residual part of the first-opening section 1322a has sufficient strength, reducing the risk of the side wall 13 cracking along the first-opening section 1322a in advance during long-term cycling of the battery cell 10, thereby improving the service life of the battery cell 10; T1 / D≤0.9, so that the minimum residual thickness of the first-opening section 1322a accounts for not too large a proportion of the wall thickness of the side wall 13, so that the side wall 13 can be cracked more promptly in the first-opening section 1322a when the battery cell 10 thermally runs away, thereby shortening the time it takes for the side wall 13 to crack along the first groove 132, thereby reducing the risk of fire or explosion of the battery cell 10.

[0187] In some embodiments, 0.1≤T1 / D≤0.5.

[0188] In this embodiment, T1 / D can be any point value among 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, and 0.5, or a range of values ​​between any two of them.

[0189] In this embodiment, T1 / D≥0.1, which further increases the proportion of the minimum residual thickness of the first-opening section 1322a in the wall thickness of the side wall 13, and further reduces the risk of the side wall 13 cracking prematurely along the first-opening section 1322a during long-term recycling use of the battery cell 10; T1 / D≤0.5, which further reduces the proportion of the minimum residual thickness of the first-opening section 1322a in the wall thickness of the side wall 13, and further reduces the risk of fire or explosion of the battery cell 10.

[0190] In some embodiments, please continue to refer to FIG. 6 . On the extension path of the second slot section 1322 , the slot length of the first opening section 1322 a is L, and 0.2 mm ≤ L ≤ 10 mm.

[0191] In this embodiment, L can be any point value among 0.2mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, and 10mm, or a range value between any two of them.

[0192] L≥0.2mm, so that the groove length of the first opening section 1322a is not too small, which can reduce the processing difficulty of the first opening section 1322a; L≤10mm, so that the groove length of the first opening section 1322a is not too large, which can achieve precise control of the detonation position of the side wall 13 and improve the accuracy of the detonation position.

[0193] In some embodiments, 1 mm ≤ L ≤ 6 mm.

[0194] In this embodiment, in this embodiment, L can take any point value of 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.8mm, 3mm, 3.2mm, 3.5mm, 3.8mm, 4mm, 4.2mm, 4.5mm, 4.8mm, 5mm, 5.2mm, 5.5mm, 5.8mm, 6mm, or a range value between any two of them.

[0195] In this embodiment, L≥1mm, further increasing the groove length of the first-opening section 1322a and further reducing the processing difficulty of the first-opening section 1322a; L≤6mm, further reducing the groove length of the first-opening section 1322a and further improving the accuracy of the detonation position of the side wall 13.

[0196] In some embodiments, referring to FIG. 6 , the first slot segment 1321 , the second slot segment 1322 and the third slot segment 1323 are sequentially connected to form a continuously arranged first groove 132 , and the first slot segment 1321 and the third slot segment 1323 are arranged opposite to each other.

[0197] The first slot segment 1321 and the third slot segment 1323 may be arranged in parallel; the first slot segment 1321 and the third slot segment 1323 may also be arranged at a non-zero angle, for example, the angle between the first slot segment 1321 and the third slot segment 1323 is less than or equal to 10°. The first slot segment 1321 and the third slot segment 1323 may extend along an arc trajectory, the center of which is located on the centerline O of the side wall 13, and the plane of the arc trajectory is perpendicular to the centerline O of the side wall 13. The first slot segment 1321 and the third slot segment 1323 may also extend along an elliptical trajectory, the plane of which is not perpendicular to the centerline O of the side wall 13, and the angle between the plane of the elliptical trajectory and the centerline O of the side wall 13 may be greater than 0° and less than 90°.

[0198] The first groove section 1321, the second groove section 1322, and the third groove section 1323 can define a predetermined pressure relief area 134. The predetermined pressure relief area 134 can be flipped outward and opened after the side wall 13 is split along at least a portion of the first groove 132. It is understood that the first groove section 1321, the second groove section 1322, and the third groove section 1323 are located at the edge of the predetermined pressure relief area 134.

[0199] In this embodiment, the first, second, and third groove sections 1321, 1322, and 1323 are sequentially connected, with the first and third groove sections 1321 and 1323 positioned opposite each other, resulting in a U-shaped groove and a simple structure. Furthermore, the first, second, and third groove sections 1321, 1322, 1323 define a predetermined pressure relief area 134. When the battery cell 10 releases pressure, the predetermined pressure relief area 134 rapidly opens outward by flipping, thereby increasing the pressure relief area of ​​the battery cell 10 and effectively improving the pressure relief rate of the battery cell 10.

[0200] In some embodiments, the first slot segment 1321 and the third slot segment 1323 are both smoothly connected to the second slot segment 1322 .

[0201] As an example, the second slot segment 1322 extends along a spatial curved trajectory and is an arcuate slot when the sidewall 13 is unfolded into a flat plate structure. The first slot segment 1321 and the third slot segment 1323 are both tangent to the second slot segment 1322, so that the first slot segment 1321 and the third slot segment 1323 are smoothly connected to the second slot segment 1322.

[0202] In this embodiment, the first groove section 1321 and the third groove section 1323 are both smoothly connected to the second groove section 1322. On the one hand, after the side wall 13 is cracked along the second groove section 1322, it can be smoothly cracked along the first groove section 1321 and the third groove section 1323, shortening the time for the side wall 13 to be cracked along the first groove 132, and making the predetermined pressure relief area 134 smoother in the process of flipping toward the outside of the shell 1; on the other hand, it can effectively reduce the stress concentration coefficient at the connection position between the first groove section 1321 and the second groove section 1322 and the connection position between the third groove section 1323 and the second groove section 1322, thereby improving the fatigue strength of the side wall 13 and effectively improving the service life of the battery cell 10.

[0203] In some embodiments, the second slot segment 1322 includes a first connecting segment 1322b, a second connecting segment 1322c, and a first-opening segment 1322a. The first connecting segment 1322b connects the first-opening segment 1322a and the first slot segment 1321, and the second connecting segment 1322c connects the first-opening segment 1322a and the third slot segment 1323. The minimum residual thickness of the first connecting segment 1322b, the minimum residual thickness of the second connecting segment 1322c, the minimum residual thickness of the first slot segment 1321, and the minimum residual thickness of the third slot segment 1323 are all greater than the minimum residual thickness of the first-opening segment 1322a.

[0204] The first connecting section 1322b, the second connecting section 1322c, and the first-opening section 1322a are three sections of the second trough section 1322. The first connecting section 1322b, the first-opening section 1322a, and the second connecting section 1322c are connected in sequence. The first connecting section 1322b is the portion of the second trough section 1322 that connects between the first-opening section 1322a and the first trough section 1321. The second connecting section 1322c is the portion of the second trough section 1322 that connects between the first-opening section 1322a and the third trough section 1323. The minimum residual thickness of the first connecting segment 1322b is the minimum thickness of the residual part of the first connecting segment 1322b, and the residual part of the first connecting segment 1322b can be the bottom wall of the groove of the first connecting segment 1322b; the minimum residual thickness of the second connecting segment 1322c is the minimum thickness of the residual part of the second connecting segment 1322c, and the residual part of the second connecting segment 1322c can be the bottom wall of the groove of the second connecting segment 1322c; the minimum residual thickness of the first groove segment 1321 is the minimum thickness of the residual part of the first groove segment 1321, and the residual part of the first groove segment 1321 can be the bottom wall of the groove of the first groove segment 1321; the minimum residual thickness of the third groove segment 1323 is the minimum thickness of the residual part of the third groove segment 1323, and the residual part of the third groove segment 1323 can be the bottom wall of the groove of the third groove segment 1323. The minimum residual thickness of the first connecting segment 1322b, the minimum residual thickness of the second connecting segment 1322c, the minimum residual thickness of the first groove segment 1321, and the minimum residual thickness of the third groove segment 1323 can be equal, or at least two of them can be unequal. The first connecting segment 1322b, the second connecting segment 1322c, the first groove segment 1321, and the third groove segment 1323 constitute the other regions of the first groove 132. The smallest of the four minimum residual thicknesses of the first connecting segment 1322b, the second connecting segment 1322c, the first groove segment 1321, and the third groove segment 1323 is the minimum residual thickness of the other regions of the first groove 132.

[0205] Along the extension path of the second slot section 1322, the slot length of the first connecting section 1322b can be equal to or different from the slot length of the second connecting section 1322c. As an example, in the embodiment shown in FIG6, the slot length of the first connecting section 1322b is equal to the slot length of the second connecting section 1322c, so that the first opening section 1322a is centrally located in the second slot section 1322.

[0206] In this embodiment, the minimum residual thickness of the first connecting section 1322b, the minimum residual thickness of the second connecting section 1322c, the minimum residual thickness of the first groove section 1321, and the minimum residual thickness of the third groove section 1323 are all greater than the minimum residual thickness of the first opening section 1322a, so that the strength of the residual portion of the first opening section 1322a is less than the strength of the residual portion of the first connecting section 1322b, the strength of the residual portion of the second connecting section 1322c, the strength of the residual portion of the first groove section 1321, and the strength of the residual portion of the third groove section 1323, so that the side wall 13 can be cracked preferentially in the first opening section 1322a when the battery cell 10 thermally runs away. Furthermore, since the second groove section 1322 includes a first connecting section 1322b, a second connecting section 1322c and a first-opening section 1322a, and the first-opening section 1322a and the first groove section 1321 are connected by the first connecting section 1322b, and the first-opening section 1322a and the third groove section 1323 are connected by the second connecting section 1322c, the first-opening section 1322a is the middle section of the second groove section 1322, so that after the side wall 13 is cracked at the position of the first-opening section 1322a, it can quickly crack along the first connecting section 1322b and the second connecting section 1322c located at both ends of the first-opening section 1322a, thereby shortening the time it takes for the side wall 13 to crack along the second groove section 1322, and thereby enabling the side wall 13 to quickly crack along the first groove section 1321 and the third groove section 1323. When the length of the second groove section 1322 is constant, the setting of the first connecting section 1322b and the second connecting section 1322c can reduce the length of the first opening section 1322a, so that the side wall 13 can be cracked more promptly from the first opening section 1322a when the battery cell 10 thermally runs away, and the detonation position of the side wall 13 can be more accurate.

[0207] In some embodiments, the minimum residual thickness of the first connecting segment 1322b is equal to the minimum residual thickness of the first slot segment 1321; and / or, the minimum residual thickness of the second connecting segment 1322c is equal to the minimum residual thickness of the third slot segment 1323; and / or, the minimum residual thickness of the first connecting segment 1322b is equal to the minimum residual thickness of the second connecting segment 1322c; and / or, the minimum residual thickness of the first slot segment 1321 is equal to the minimum residual thickness of the third slot segment 1323.

[0208] As an example, the minimum residual thickness of the first connecting segment 1322b, the minimum residual thickness of the first groove segment 1321, the minimum residual thickness of the second connecting segment 1322c, and the minimum residual thickness of the third groove segment 1323 are equal. The minimum residual thickness of the first connecting segment 1322b, the minimum residual thickness of the first groove segment 1321, the minimum residual thickness of the second connecting segment 1322c, and the minimum residual thickness of the third groove segment 1323 can all serve as the minimum residual thickness of other areas of the first groove 132. The maximum groove depths of the first connecting segment 1322b, the first groove segment 1321, the second connecting segment 1322c, and the third groove segment 1323 are all equal. The sum of the minimum residual thickness of the first connecting section 1322b and the maximum groove depth of the first connecting section 1322b, the sum of the minimum residual thickness of the first groove section 1321 and the maximum groove depth of the first groove section 1321, the sum of the minimum residual thickness of the second connecting section 1322c and the maximum groove depth of the second connecting section 1322c, and the sum of the minimum residual thickness of the third groove section 1323 and the maximum groove depth of the third groove section 1323 are all equal to the wall thickness of the side wall 13.

[0209] When forming the first groove 132, the first groove section 1321, the second groove section 1322 and the third groove section 1323 can be processed at one time according to the groove depth of the first groove section 1321, and then the second groove section 1322 can be processed again to make the local part of the second groove section 1322 deeper, thereby dividing the second groove section 1322 into a first connecting section 1322b, a first opening section 1322a and a second connecting section 1322c, and finally achieving the minimum residual thickness of the first connecting section 1322b, the minimum residual thickness of the first groove section 1321, the minimum residual thickness of the second connecting section 1322c and the minimum residual thickness of the third groove section 1323 are equal, and all are greater than the minimum residual thickness of the first opening section 1322a. This can effectively reduce the difficulty of forming the first groove 132 and improve the forming efficiency of the first groove 132.

[0210] In some embodiments, the extension trajectory of the first slot segment 1321 is located in the first plane U, and the angle between the center line O of the side wall 13 and the first plane U is α1, where 30°≤α1≤90°.

[0211] α1 can take any point value among 30°, 32°, 35°, 38°, 40°, 42°, 45°, 48°, 50°, 52°, 55°, 58°, 60°, 62°, 65°, 68°, 70°, 72°, 75°, 78°, 80°, 82°, 85°, 88°, 90° or any range value between any two of them.

[0212] It can be understood that if α1=90°, the first groove segment 1321 extends along the circumferential direction Y of the side wall 13, and the extension trajectory line of the first groove segment 1321 is an arc; if 30°≤α1<90°, the extension trajectory line of the first groove segment 1321 is an ellipse.

[0213] In this embodiment, 30°≤α1≤90°, so that the angle between the center line O of the side wall 13 and the first plane U is controlled within a reasonable range, which can reduce the risk of the side wall 13 being torn by continuing to crack along the extension line of the first groove section 1321 after cracking along the first groove section 1321.

[0214] In some embodiments, the extension trajectory of the third slot segment 1323 is located in the second plane V, and the angle between the center line O of the side wall 13 and the second plane V is α2, where 30°≤α2≤90°.

[0215] α2 can take any point value among 30°, 32°, 35°, 38°, 40°, 42°, 45°, 48°, 50°, 52°, 55°, 58°, 60°, 62°, 65°, 68°, 70°, 72°, 75°, 78°, 80°, 82°, 85°, 88°, 90° or any range value between any two of them.

[0216] It may be α2=α1, α2<α1, or α2>α1.

[0217] As an example, in the embodiment shown in FIG. 6 , the third slot segment 1323 is parallel to the first slot segment 1321 , the second plane V is parallel to the first plane U, and α2 = α1 = 90°.

[0218] Optionally, 40°≤α1≤75°, 40°≤α2≤75°, so that the predetermined pressure relief area 134 defined by the first slot segment 1321, the second slot segment 1322 and the third slot segment 1323 can be in an inclined state, reducing the space swept by the predetermined pressure relief area 134 during the outward flipping process, and reducing the risk of the predetermined pressure relief area 134 being blocked by other battery cells 10, thereby reducing the flipping angle of the predetermined pressure relief area 134.

[0219] In this embodiment, 30°≤α2≤90°, so that the angle between the center line O of the side wall 13 and the second plane V is controlled within a reasonable range, which can reduce the risk of the side wall 13 being torn by continuing to crack along the extension line of the third groove section 1323 after cracking along the third groove section 1323.

[0220] In some embodiments, referring to FIG. 8 and FIG. 9 , the width of the first groove 132 is W1 , the width of the second groove 133 is W2 , and |W2 − W1| ≤ 0.1 mm.

[0221] |W2-W1| can take any point value among 0mm, 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, or a range between any two of them.

[0222] It can be W2>W1, W2<W1, or W2=W1.

[0223] The groove width of the first groove 132 is the maximum width of the notch of the first groove 132 in the width direction of the first groove 132. Taking the example of the first groove 132 being provided on the outer surface 135 of the sidewall 13, the notch of the first groove 132 is located on the outer surface 135 of the sidewall 13. The maximum width of the notch of the first groove 132 can be measured on the outer surface 135 of the sidewall 13, thereby measuring the groove width of the first groove 132. The groove width of the second groove 133 is the maximum width of the notch of the second groove 133 in the width direction of the second groove 133. Taking the example of the second groove 133 being provided on the outer surface 135 of the sidewall 13, the notch of the second groove 133 is located on the outer surface 135 of the sidewall 13. The maximum width of the notch of the second groove 133 can be measured on the outer surface 135 of the sidewall 13, thereby measuring the groove width of the second groove 133.

[0224] In this embodiment, |W2-W1|≤0.1mm ensures that the width of the second groove 133 does not differ too much from the width of the first groove 132, which is beneficial to reducing the difference in the extrusion amount between the first groove 132 and the second groove 133 when processing the first groove 132 and the second groove 133, reducing the deformation of the side wall 13, and improving the roundness of the side wall 13.

[0225] In some embodiments, the first groove 132 is disposed on the outer surface 135 of the sidewall 13 ; and / or the second groove 133 is disposed on the outer surface 135 of the sidewall 13 .

[0226] As an example, in the embodiments shown in FIG. 8 and FIG. 9 , the second groove 133 and the first groove 132 are both provided on the outer surface 135 of the side wall 13 and are both stamped and formed on the side wall 13 .

[0227] If the first groove 132 is set on the outer surface 135 of the side wall 13, the first groove 132 can be processed on the outside of the side wall 13, reducing the difficulty of processing the first groove 132; if the second groove 133 is set on the outer surface 135 of the side wall 13, the second groove 133 can be processed on the outside of the side wall 13, reducing the difficulty of processing the second groove 133.

[0228] In some embodiments, the first groove 132 is a groove extending along a non-closed trajectory; and / or the second groove 133 is a groove extending along a non-closed trajectory.

[0229] In an embodiment where the first groove 132 includes a first groove segment 1321, a second groove segment 1322, and a third groove segment 1323, the first groove segment 1321 and the third groove segment 1323 may not contact each other, so that the first groove 132 is a groove extending along a non-closed trajectory; or the first groove segment 1321 and the third groove segment 1323 may be connected, so that the first groove segment 1321, the second groove segment 1322, and the third groove segment 1323 are connected end to end, so that the second groove 133 is a groove extending along a non-closed trajectory.

[0230] The first groove 132 extends along a non-enclosed path. This structure of the first groove 132 improves the sidewall 13's fatigue resistance, reducing the risk of premature cracking along the first groove 132 during long-term cycling of the battery cell 10. Furthermore, after the sidewall 13 cracks along the first groove, the exposed portion of the sidewall 13 is less susceptible to splashing. If the second groove 133 extends along a non-enclosed path, the sidewall 13 has improved impact resistance, reducing the risk of the sidewall 13 cracking along the second groove 133 due to impact forces near the second groove 133.

[0231] 4 , openings are formed at opposite ends of the side wall 13 along the axial direction X of the side wall 13. The housing 1 further includes two end covers 12, which respectively close the openings at the two ends of the side wall 13.

[0232] It can be understood that the side wall 13 is a hollow structure with openings formed at two opposite ends, and the side wall 13 is the shell 11 of the housing 1 .

[0233] The housing 11 can be formed from a sheet material by stretching, and the side wall 13 and the end cover 12 can be connected by welding or crimping.

[0234] In this embodiment, the sidewall 13 is a hollow structure with openings formed at both opposing ends. The electrode assembly 2 can be assembled into the sidewall 13 through either opening, which can reduce the difficulty of assembling the battery cell 10 and improve the assembly quality of the battery cell 10. This structure of the sidewall 13 is less difficult to form, and the length of the sidewall 13 (the axial X dimension of the sidewall 13) can be increased, which helps to increase the capacitance of the battery cell 10.

[0235] In some embodiments, please refer to Figure 12, which is an exploded view of a battery cell 10 provided in some embodiments of the present application. The housing 1 includes a shell 11 and an end cap 12. The shell 11 includes a side wall 13 and a bottom wall 14. Along the axial direction X of the side wall 13, one end of the side wall 13 is connected to the bottom wall 14, and the other end of the side wall 13 forms an opening, which is sealed by the end cap 12.

[0236] It is understood that the housing 11 is a hollow structure with an opening at one end. The housing 1 includes only one end cap 12, each of which seals one opening in the housing 11. The bottom wall 14 is the wall portion of the housing 11 opposite the end cap 12. The side walls 13 and bottom wall 14 can be integrally formed. For example, the housing 11 can be formed from sheet material by stretching to achieve integral formation of the side walls 13 and bottom wall 14. The side walls 13 and end cap 12 can be connected by welding or crimping.

[0237] As an example, in the embodiment shown in Figure 12, along the axial direction X of the side wall 13, pole ears 21 are formed at the opposite ends of the electrode assembly 2, and the pole ears 21 at both ends of the electrode assembly 2 are respectively a positive pole ear and a negative pole ear. The end cover 12 is provided with an electrode terminal 3, and the electrode terminal 3 is electrically connected to the positive pole ear. The bottom wall 14 of the shell 11 is electrically connected to the negative pole ear.

[0238] In this embodiment, the housing 11 is a hollow structure with an opening at one end. The battery cell 10 only needs one end cover 12 to cooperate with the housing 11 , which can simplify the structure of the battery cell 10 .

[0239] In some embodiments, the material of the side wall 13 includes steel.

[0240] The steel may be carbon steel, stainless steel or the like.

[0241] In some embodiments, the sidewall 13 is made of aluminum alloy.

[0242] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other individual elements ≤ 0.03%.

[0243] This aluminum alloy has lower hardness and better forming ability, which reduces the difficulty of processing the first groove 132 , is conducive to improving the processing accuracy of the first groove 132 , and improves the pressure relief consistency of the side wall 13 .

[0244] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 96.7%, 0.05% ≤ copper ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other individual element components ≤ 0.05%, and the total composition of other elements ≤ 0.15%.

[0245] The side wall 13 made of this aluminum alloy has higher hardness, greater strength and good anti-destruction ability.

[0246] An embodiment of the present application provides a battery 100 , comprising the battery cell 10 provided in any one of the above embodiments.

[0247] The present application also provides an electrical device, comprising the battery cell 10 provided by any one of the above embodiments, and the battery cell 10 is used to provide electrical energy to the electrical device.

[0248] Referring to Figures 3 to 11, an embodiment of the present application provides a cylindrical battery cell, comprising a housing 1 and an electrode assembly 2, wherein the electrode assembly 2 is housed within the housing 1. The housing 1 is cylindrical and comprises a shell 11 and two end caps 12. The shell 11 has openings formed at opposite ends thereof. The shell 11 forms a sidewall 13 of the housing 1, and the sidewall 13 surrounds the outside of the electrode assembly 2. The two end caps 12 respectively close the two openings of the shell 11. Along the axial direction X of the sidewall 13, tabs 21 are formed at both ends of the electrode assembly 2, namely a positive tab and a negative tab. Both end caps 12 are provided with electrode terminals 3. The electrode terminal 3 on one end cap 12 is connected to the positive tab via a current collecting component 4, and the electrode terminal 3 on the other end cap 12 is connected to the negative tab via another current collecting component 4.

[0249] The sidewall 13 is provided with two groove groups 131, spaced apart along the axial direction X of the sidewall 13. Each groove group 131 includes multiple grooves, spaced apart and evenly distributed along the circumferential direction Y of the sidewall 13. A portion of the multiple grooves are first grooves 132, and another portion are second grooves 133. There are multiple first grooves 132 and second grooves 133, each of which is alternately arranged along the circumferential direction Y of the sidewall 13. The total number of first grooves 132 and second grooves 133 in a groove group 131 is 6 to 15. Both first grooves 132 and second grooves 133 are provided on the outer surface 135 of the sidewall 13. The sidewall 13 is configured to rupture along at least a portion of the first groove 132 when the battery cell 10 is depressurized.

[0250] Among them, the first groove 132 has a first-opening section 1322a that cracks first, and the first groove 132 includes a first groove section 1321, a second groove section 1322 and a third groove section 1323. The second groove section 1322 connects the first groove section 1321 and the third groove section 1323. The first groove section 1321, the second groove section 1322 and the third groove section 1323 are connected in sequence, and the first groove section 1321 and the third groove section 1323 are arranged opposite to each other. The second groove section 1322 includes a first connecting section 1322b, a pre-opening section 1322a, and a second connecting section 1322c. The first connecting section 1322b connects the pre-opening section 1322a and the first groove section 1321, while the second connecting section 1322c connects the pre-opening section 1322a and the third groove section 1323. The minimum residual thicknesses of the first groove section 1321, the first connecting section 1322b, the second connecting section 1322c, and the third groove section 1323 are equal and greater than the minimum residual thickness of the pre-opening section 1322a. The minimum residual thickness of the second groove 133 is greater than the minimum residual thickness of the pre-opening section 1322a. Along the extension path of the first groove 132, the groove length of the first groove section 1321 is equal to the groove length of the third groove section 1323, and the groove length of the first connecting section 1322b is equal to the groove length of the second connecting section 1322c.

[0251] The residual thickness of the first opening section 1322a is T1, and the wall thickness of the sidewall 13 is D, with 0.04 ≤ T1 / D ≤ 0.9. Along the extension path of the second slot section 1322, the slot length of the first opening section 1322a is L, with 0.2 mm ≤ L ≤ 10 mm. The extension trajectory of the first slot section 1321 lies within the first plane U, with the centerline O of the sidewall 13 and the first plane U forming an angle α1, with 30° ≤ α1 ≤ 90°. The extension trajectory of the third slot section 1323 lies within the second plane V, with the centerline O of the sidewall 13 and the second plane V forming an angle α2, with 30° ≤ α2 ≤ 90°. The second plane V is parallel to the first plane U.

[0252] In such a battery cell 10, the first groove 132 is a true pressure relief groove, and the second groove 133 is a false pressure relief groove. The setting of the second groove 133 on the side wall 13 allows the side wall 13 to release stress at the position where the second groove 133 is set, thereby alleviating the deformation of the side wall 13 caused by the stress release of the side wall 13 in the first groove 132, which can effectively improve the roundness of the side wall 13, improve the assembly quality of the battery cell 10, and thus increase the service life of the battery cell 10. When a battery cell 10 experiences thermal runaway, the sidewall 13 preferentially cracks at the first-opening section 1322a of the second groove section 1322. The resulting crack can then propagate along the first and third groove sections 1321, 1323. After cracking at the first-opening section 1322a, the sidewall 13 can rapidly crack along the first and third groove sections 1321, 1323. This shortens the time it takes for the sidewall 13 to crack along the first groove 132, allowing for timely pressure relief and reducing the risk of fire or explosion during thermal runaway in the battery cell 10, thereby effectively improving the reliability of the battery cell 10. Furthermore, controlling the angle between the centerline O of the sidewall 13 and the first plane U within a range of 30° to 90° reduces the risk of the sidewall 13 continuing to crack along the extension of the first groove section 1321 after cracking along the first groove section 1321, thereby tearing the sidewall 13. By controlling the angle between the center line O of the side wall 13 and the second plane V within the range of 30° to 90°, the risk of the side wall 13 being torn by continuing to crack along the extension line of the third groove section 1323 after cracking along the third groove section 1323 can be reduced.

[0253] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0254] The above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit this application. Those skilled in the art will appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application are intended to be within the scope of protection of this application.

Claims

1. A battery cell, comprising: electrode assembly; a housing in a cylindrical shape, the housing accommodating the electrode assembly, the housing comprising a side wall disposed around the electrode assembly; The side wall is provided with a groove group, the groove group including a plurality of grooves arranged at intervals along the circumference of the side wall, the plurality of grooves including at least one first groove, and the side wall is configured to be able to break along at least a portion of the first groove when the battery cell is depressurized; The plurality of grooves further include at least one second groove, and the minimum residual thickness of the second groove is greater than the minimum residual thickness of the first groove.

2. The battery cell according to claim 1, wherein: The first grooves and the second grooves are alternately arranged along the circumference of the side wall.

3. The battery cell according to claim 1 or 2, wherein: There are multiple first grooves and multiple second grooves in the groove set.

4. The battery cell according to any one of claims 1 to 3, wherein: The sum of the number of the first grooves and the number of the second grooves in the groove group is N, and 2≤N≤20.

5. The battery cell according to claim 4, wherein: 6≤N≤15。 6. The battery cell according to any one of claims 1 to 5, wherein: The number of the first grooves and the number of the second grooves in the groove group are equal.

7. The battery cell according to any one of claims 1 to 6, wherein: Along the circumference of the side wall, the plurality of grooves in the groove group are evenly distributed on the side wall.

8. The battery cell according to any one of claims 1 to 7, wherein: The side wall is provided with a plurality of the groove groups, and the plurality of the groove groups are spaced apart along the axial direction of the side wall.

9. The battery cell according to any one of claims 1 to 8, wherein: The first groove has a first opening section that cracks preferentially. The first groove includes a first groove section, a second groove section and a third groove section. The second groove section connects the first groove section and the third groove section. At least a portion of the second groove section forms the first opening section.

10. The battery cell according to claim 9, wherein: The first groove section, the second groove section and the third groove section are sequentially connected to form a continuously arranged first groove. On the extension path of the first groove, the midpoint of the first groove is located at the first opening section.

11. The battery cell according to claim 9 or 10, wherein: On the extension path of the second slot section, the midpoint of the second slot section is located at the first opening section.

12. The battery cell according to any one of claims 9 to 11, wherein: The minimum residual thickness of the first opening section is T1, the minimum residual thickness of other areas of the first groove is T2, and the minimum residual thickness of the second groove is T3, T1<T2, T1<T3.

13. The battery cell according to claim 12, wherein: |T3-T2|≤0.1mm.

14. The battery cell according to any one of claims 9 to 13, wherein: The minimum residual thickness of the first-opening section is T1, the wall thickness of the side wall is D, and 0.04≤T1 / D≤0.

9.

15. The battery cell according to claim 14, wherein: 0.1≤T1 / D≤0.

5.

16. The battery cell according to any one of claims 9 to 15, wherein: On the extension path of the second groove section, the groove length of the first opening section is L, 0.2mm≤L≤10mm.

17. The battery cell according to claim 16, wherein: 1mm≤L≤6mm.

18. The battery cell according to any one of claims 9 to 17, wherein: The first slot segment, the second slot segment and the third slot segment are sequentially connected to form the first continuously arranged groove, and the first slot segment is arranged opposite to the third slot segment.

19. The battery cell according to claim 18, wherein: The first slot section and the third slot section are both smoothly connected to the second slot section.

20. The battery cell according to claim 18 or 19, wherein: The second slot section includes a first connecting section, a second connecting section and the first opening section, the first connecting section connects the first opening section and the first slot section, and the second connecting section connects the first opening section and the third slot section; The minimum residual thickness of the first connecting section, the minimum residual thickness of the second connecting section, the minimum residual thickness of the first slot section, and the minimum residual thickness of the third slot section are all greater than the minimum residual thickness of the first-opening section.

21. The battery cell according to claim 20, wherein: The minimum residual thickness of the first connecting section is equal to the minimum residual thickness of the first slot section; and / or The minimum residual thickness of the second connecting section is equal to the minimum residual thickness of the third slot section; and / or The minimum residual thickness of the first connecting section is equal to the minimum residual thickness of the second connecting section; and / or The minimum residual thickness of the first slot segment is equal to the minimum residual thickness of the third slot segment.

22. The battery cell according to any one of claims 9 to 21, wherein: The extension trajectory of the first slot segment is located in a first plane, and the angle formed between the center line of the side wall and the first plane is α1, and 30°≤α1≤90°.

23. The battery cell according to claim 22, wherein: The extension trajectory of the third slot segment is located in the second plane, and the angle formed between the center line of the side wall and the second plane is α2, 30°≤α2≤90°.

24. The battery cell according to any one of claims 1 to 23, wherein: The first groove has a groove width of W1, the second groove has a groove width of W2, and |W2-W1|≤0.1 mm.

25. The battery cell according to any one of claims 1 to 24, wherein: The first groove is provided on the outer surface of the side wall; and / or the second groove is provided on the outer surface of the side wall.

26. The battery cell according to any one of claims 1 to 25, wherein: The first groove is a groove extending along a non-closed track; and / or the second groove is a groove extending along a non-closed track.

27. The battery cell according to any one of claims 1 to 26, wherein: Along the axial direction of the side wall, openings are formed at both opposite ends of the side wall; The housing further includes two end covers, and the two end covers respectively close the openings at both ends of the side wall.

28. The battery cell according to any one of claims 1 to 26, wherein: The housing comprises: The housing comprises the side wall and the bottom wall, wherein one end of the side wall is connected to the bottom wall along the axial direction of the side wall, and the other end of the side wall forms an opening; An end cap closes the opening.

29. A battery comprising the battery cell according to any one of claims 1 to 28.

30. An electrical device comprising the battery cell according to any one of claims 1 to 28, wherein the battery cell is used to provide electrical energy to the electrical device.

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