Battery monomer, battery and electric equipment

Abstract

The embodiment of the invention provides a battery monomer, a battery and electric equipment, and relates to the technical field of batteries. The battery monomer comprises a shell and a pressure relief nick, and the shell comprises a first wall; the pressure relief nick is arranged on the first wall and comprises an arc section and a first extension section, the arc section is provided with a first end, and the first extension section is connected to the first end and extends in the direction close to the central axis of the arc section from the first end. According to the battery monomer provided by the embodiment of the invention, the tearing range and the tearing direction of the torn part on the shell are controllable, and after the battery monomer is subjected to thermal runaway and the pressure relief nick is torn, local valve opening can be realized, so that the probability of tearing the shell in a large range is reduced, and the damage to the battery monomer caused by uncontrollable cracks is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and more particularly, to a battery cell, a battery, and an electrical device. Background Art

[0002] Energy conservation and emission reduction are the keys to the sustainable development of the automotive industry. Electric vehicles have become an important part of the sustainable development of the automotive industry due to their advantages of energy conservation and environmental protection. For electric vehicles, battery technology is an important factor related to their development.

[0003] Batteries are widely used in fields such as portable electronic devices, electric transportation vehicles, electric tools, drones, energy storage devices, etc. During the use of batteries, reliability is an issue that cannot be ignored. Therefore, how to improve the reliability of batteries is a technical problem that urgently needs to be solved in battery technology. Summary of the Invention

[0004] The present application provides a battery cell, a battery, and an electrical device, which can reduce the damage degree of the outer shell when the battery cell undergoes thermal runaway, reduce the impact on other battery cells, and thus improve the reliability of the battery.

[0005] The present application is implemented by the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a battery cell, including an outer shell and a pressure relief indentation. The outer shell includes a first wall; the pressure relief indentation is provided on the first wall. The pressure relief indentation includes an arc segment and a first extension segment. The arc segment has a first end, and the first extension segment is connected to the first end and extends from the first end towards the direction close to the central axis of the arc segment.

[0007] For the battery cell according to the embodiment of the present application, the pressure relief indentation includes an arc segment and a first extension segment. By extending the first extension segment from the first end towards the direction close to the central axis of the arc segment, the arc segment can reduce the stress concentration during the processing of the pressure relief indentation. When the battery cell undergoes thermal runaway and the internal high-pressure gas tears the pressure relief indentation, the first extension segment can guide the crack towards the direction close to the central axis of the arc segment, so that the size of the torn part on the outer shell is controllable. Of course, the first extension segment can also make the tearing direction of the crack controllable. Thus, after the battery cell undergoes thermal runaway and the pressure relief indentation is torn, local valve opening can be realized, reducing the probability of large-scale tearing of the outer shell. Both the tearing direction and the tearing range of the crack are controllable, reducing the damage caused to the battery cell due to the uncontrollability of the crack.

[0008] According to some embodiments of the present application, the pressure relief notch further includes a second extension section. The arc section has a second end, and the second extension section is connected to the second end and extends from the second end towards the direction close to the central axis. In the above solution, the second extension section can guide the crack towards the direction close to the central axis of the arc section. The second extension section and the first extension section can make the crack have a converging trend, so that the tearing direction and tearing range of the crack are controllable, realizing local valve opening of the outer shell.

[0009] According to some embodiments of the present application, the first extension section and the second extension section are symmetrical about the central axis. In the above solution, the extension lengths of the first extension section and the second extension section are the same. If both the first extension section and the second extension section are straight lines, the angle between the extension line of the first extension section and the central axis is the same as the angle between the extension line of the second extension section and the central axis. Thus, the tearing direction and tearing range of the crack guided by the first extension section and the second extension section can be kept substantially the same, reducing the probability of uncontrollability of the crack and further realizing stable local valve opening of the outer shell.

[0010] According to some embodiments of the present application, the length of the first extension section is the same as the length of the second extension section. In the above solution, the valve opening area of the crack at the first extension section is approximately the same as the valve opening area of the crack at the second extension section, and the subsequent valve opening area of the outer shell after the crack is guided by the first extension section is also substantially the same as the subsequent valve opening area of the outer shell after the crack is guided by the second extension section, thus ensuring the stability of the tearing range of the crack and reducing the probability of uncontrollability of the crack.

[0011] According to some embodiments of the present application, both the first extension section and the second extension section are straight line segments, and the angle between the extension line of the first extension section and the central axis is the same as the angle between the extension line of the second extension section and the central axis. In the above solution, the cracks guided by the first extension section and the second extension section can converge on the central axis, thus realizing local valve opening of the outer shell.

[0012] According to some embodiments of the present application, the length of the first extension section is less than the length of the second extension section. In the above solution, the subsequent valve opening area of the outer shell after the crack is guided by the first extension section is larger than the subsequent valve opening area of the outer shell after the crack is guided by the second extension section, so that after the battery cell undergoes thermal runaway, the high-pressure gas in the outer shell can be quickly discharged.

[0013] According to some embodiments of the present application, both the first extension section and the second extension section are straight line segments, and the included angle between the extension line of the first extension section and the central axis is different from the included angle between the extension line of the second extension section and the central axis. In the above solution, the subsequent valve opening area of the outer shell after the crack is guided by the first extension section is different from the subsequent valve opening area of the outer shell after the crack is guided by the second extension section. Thus, after the battery cell undergoes thermal runaway, the high-pressure gas inside the outer shell can be quickly discharged through the larger valve opening area on the outer shell.

[0014] According to some embodiments of the present application, the central angle of the arc section is α, satisfying: 180° ≤ α < 360°. In the above solution, when α ≥ 180°, the area enclosed by the arc section is sufficient. Thus, when the battery cell undergoes thermal runaway, the crack tears the outer shell along the arc section, and the crack on the arc section can enable the high-pressure gas inside the outer shell to be quickly discharged; when α < 360°, the pressure relief notch is an unclosed annular structure with an opening on the pressure relief notch. Thus, the crack can tear the outer shell along the orientation of the opening, making the tearing direction and range of the crack controllable, and further realizing local valve opening of the crack on the outer shell. When 180° ≤ α < 360°, it can not only make the range of the crack torn along the arc section sufficient and the high-pressure gas inside the outer shell can be quickly discharged, but also there is an opening on the pressure relief notch, which can guide the tearing direction and range of the crack, realizing local valve opening of the crack on the outer shell.

[0015] According to some embodiments of the present application, 210° ≤ α ≤ 330°. In the above solution, when α ≥ 210°, the area enclosed by the arc section is further increased. Thus, when the battery cell undergoes thermal runaway, the crack tears the outer shell along the arc section, and the tearing range of the crack can enable the high-pressure gas inside the outer shell to be discharged more quickly; when α ≤ 330°, the pressure relief notch is an unclosed annular structure with a larger opening on the pressure relief notch. Thus, the crack can tear the outer shell along the orientation of the opening. Not only is the tearing direction and range of the crack controllable, but also the tearing range of the crack is larger. Further, the high-pressure gas inside the outer shell can be discharged more quickly. When 210° ≤ α ≤ 330°, the discharge speed of the high-pressure gas inside the outer shell can be further increased, and at the same time, the opening size on the arc section is larger. Thus, it can guide the tearing range of the crack on the outer shell to be larger. Thus, the opening can not only guide the tearing direction and range of the crack, but also further increase the discharge speed of the high-pressure gas inside the outer shell.

[0016] According to some embodiments of the present application, the first extension segment is tangent to the arc segment; and / or the second extension segment is tangent to the arc segment. In the above solution, the crack on the arc segment can extend and tear very smoothly along the tangent line at the first end of the arc segment, reducing the obstruction during the crack tearing process, making the crack tearing smoother and more controllable, and reducing the stress concentration during the tearing process; or / and the crack on the arc segment can extend and tear very smoothly along the tangent line at the second end of the arc segment, reducing the obstruction during the crack tearing process, making the crack tearing smoother and more controllable, and reducing the stress concentration during the tearing process.

[0017] According to some embodiments of the present application, the first extension segment is a straight line segment; and / or the second extension segment is a straight line segment. In the above solution, on the one hand, it is easier to process the first extension segment, and on the other hand, the tearing process of the crack on the straight line segment is smoother. Or rather, the straight line segment can better guide the crack to tear along the preset direction, so that the tearing direction and range of the crack are more controllable; and / or on the one hand, it is easier to process the second extension segment, and on the other hand, the tearing process of the crack on the straight line segment is smoother. Or rather, the straight line segment can better guide the crack to tear along the preset direction, so that the tearing direction and range of the crack are more controllable.

[0018] According to some embodiments of the present application, the radius of the arc segment is R, satisfying: 1 mm ≤ R ≤ 20 mm; the length of the straight line segment is L 1 , satisfying: 0 < L 1 ≤ 20 mm. In the above solution, on the one hand, it can meet the pressure relief requirement of the battery cell during thermal runaway, and on the other hand, it can also prevent the range of the pressure relief notch from being too large to affect the overall structural strength of the housing.

[0019] According to some embodiments of the present application, 3 mm ≤ R ≤ 10 mm, 1 mm ≤ L 1 ≤ 10 mm. In the above solution, it can further meet the pressure relief requirement of the battery cell during thermal runaway, and on the other hand, it can also prevent the range of the pressure relief notch from being too large and further ensure the overall structural strength of the housing.

[0020] According to some embodiments of the present application, satisfying: 0 < L 1 / R ≤ 2. In the above solution, it can not only ensure that the straight line segment has enough length to guide the tearing direction and range of the crack, but also alleviate the excessive negative impact on the structural strength of the housing caused by the overly long extension of the straight line segment resulting in too large a range of the pressure relief notch.

[0021] According to some embodiments of the present application, satisfying: 0.1 ≤ L 1 / R≤1. In the above scheme, it can ensure that the straight line segment has sufficient length to guide the tearing direction and tearing range of the crack, and at the same time further alleviate the excessive negative impact on the structural strength of the shell caused by the excessive extension of the straight line segment resulting in an excessively large range of the pressure relief notch.

[0022] According to some embodiments of the present application, the end of the first extension section away from the arc section and the end of the second extension section away from the arc section are spaced apart to form an opening. In the above scheme, after the battery cell thermal runaway, the high-pressure gas will tear the pressure relief notch, and the crack can be torn along the direction of the opening toward the corner, so that the tearing direction of the crack can be adjusted by adjusting the direction of the opening.

[0023] According to some embodiments of the present application, the shell is flat, and the first wall is the wall of the shell in the thickness direction. In the above scheme, the pressure relief notch is not set on the small face, but on the large face of the shell. Therefore, the pressure relief notch is not constrained by the size of the small face, and the pressure relief notch can be designed to a suitable size as needed. In addition, the pressure relief notch is set on the large face to reduce the processing difficulty of the pressure relief notch, so that the manufacturing cost of the pressure relief notch is reduced.

[0024] According to some embodiments of the present application, the pressure relief notch is arranged in the corner area of ​​the first wall and the opening faces the corner of the first wall. In the above scheme, the pressure relief notch is arranged in the corner area of ​​the first wall. When the battery cell has thermal runaway, the crack can tear the shell under the guidance of the pressure relief notch. Since the pressure relief notch is arranged in the corner area of ​​the first wall, the tearing area of ​​the crack is also mainly concentrated in the corner area of ​​the first wall, thereby reducing the probability of the crack damaging other areas of the first wall, making it possible to recycle the shell of the battery cell after thermal runaway occurs.

[0025] When the crack tears the shell along the pressure relief notch, it can be torn along the direction of the opening, and the tearing direction of the crack is toward the corner of the first wall, thereby reducing the probability of the crack moving toward the middle area of ​​the first wall and reducing the probability of the first wall being completely torn, so that the shell can be recycled.

[0026] According to some embodiments of the present application, the first wall includes a first edge and a second edge, the first edge and the second edge intersect to form a corner of the first wall; the shortest distance between the center of the pressure relief notch and the first edge is L 2 , the length of the second edge is L, satisfying: 0<L 2 <L / 2; the shortest distance between the center of the pressure relief notch and the second edge is W 1 , the length of the first edge is W, satisfying: 0<W 1 <W / 2.

[0027] In the above solution, the center of the pressure relief notch is close to a corner defined by the first edge and the second edge. Thus, the tearing area of the crack is also mainly concentrated in the corner area of the first wall, which can reduce the probability of damage to other areas of the first wall by the crack, making it possible to recycle the outer shell of the battery cell after thermal runaway occurs.

[0028] According to some embodiments of the present application, the shortest distance between the end of the first extension segment away from the arc segment and the first edge is L 3 , the length of the second edge is L, satisfying: 0 < L 3 < L / 2; the shortest distance between the end of the second extension segment away from the arc segment and the second edge is W 2 , the length of the first edge is W, satisfying: 0 < W 2 < W / 2.

[0029] In the above solution, the shortest distance between the end of the second extension segment away from the arc segment and the second edge and the length of the first edge satisfy the above conditions, so the opening faces the corner defined by the first edge and the second edge. When the crack tears the outer shell along the pressure relief notch, it can tear along the direction of the opening, that is, the tearing direction of the crack faces the corner of the first wall, thereby reducing the probability of the crack moving towards the middle area of the first wall and reducing the probability of the first wall being completely torn, making it possible to recycle the outer shell.

[0030] According to some embodiments of the present application, the pressure relief notch is provided in the central area of the first wall. In the above solution, the pressure relief notch is provided in the central area of the first wall. At the same time, since the pressure relief notch has an opening, when the battery cell undergoes thermal runaway, the crack will extend along the pressure relief notch and towards the area where the opening faces, so that the crack will not tear randomly and will not damage most areas of the first wall, but can be guided to a preset area.

[0031] According to some embodiments of the present application, the wall thickness of the first wall is T, satisfying: 0.03 mm ≤ T ≤ 0.6 mm. In the above solution, on the one hand, it can ensure that the thickness of the first wall is thin enough to improve the energy density of the battery cell in the thickness direction of the first wall. On the other hand, it can also make the first wall have sufficient structural strength, which is convenient for subsequent laser etching of the pressure relief notch on it.

[0032] According to some embodiments of the present application, T satisfies: 0.05 mm ≤ T ≤ 0.2 mm. In the above solution, on the one hand, it can ensure that the thickness of the first wall is thin enough to further improve the energy density of the battery cell in the thickness direction of the first wall. On the other hand, it can also further ensure the structural strength of the first wall, which is convenient for subsequent laser etching of the pressure relief notch on it.

[0033] According to some embodiments of the present application, the outer shell includes a housing and a cover plate. The housing includes a bottom wall and a peripheral side wall. One end of the peripheral side wall is connected to the outer periphery of the bottom wall, and the other end of the peripheral side wall encloses a first opening. The cover plate closes the first opening; wherein the first wall is the cover plate or the bottom wall.

[0034] In the above solution, the outer shell is jointly formed by two split components, namely the housing and the cover plate. The housing and the cover plate can be metal parts, and the two can be fixed together by welding. The first wall is the cover plate or the bottom wall. Therefore, the pressure relief notch is provided on the cover plate or the bottom wall. For example, if the battery cell is flat and the cover plate and the bottom wall are opposite in the thickness direction, the pressure relief notch is provided on the large surface of the outer shell.

[0035] In a second aspect, an embodiment of the present application provides a battery, including the above battery cell. In the above solution, since the battery according to the embodiment of the present application is provided with the above battery cell, the pressure relief notch can be torn when the battery cell is out of control due to heat, and the size and tearing direction of the torn part on the outer shell are controllable, realizing local valve opening and reducing the probability of tearing the outer shell on a large scale.

[0036] In a third aspect, an embodiment of the present application provides an electrical equipment, including the above battery cell or the above battery, and the battery cell or the battery is used to provide electrical energy. In the above solution, since the electrical equipment according to the embodiment of the present application is provided with the above battery cell or battery, the safety of the electrical equipment is improved.

[0037] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present application. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0039] Figure 1 Schematic diagram of a vehicle provided by an embodiment of the present application;

[0040] Figure 2 Explosion diagram of a battery provided by an embodiment of the present application;

[0041] Figure 3 Explosion diagram of a battery cell provided by an embodiment of the present application;

[0042] Figure 4 Schematic diagram of the first wall provided by an embodiment of the present application;

[0043] Figure 5 is Figure 4 Partial enlarged schematic diagram of the circled A;

[0044] Figure 6 Schematic diagram of another first wall provided by an embodiment of the present application;

[0045] Figure 7 Partial cross-sectional view of the first wall of an embodiment of the present application;

[0046] Figure 8 Schematic diagram of yet another first wall provided by an embodiment of the present application;

[0047] Figure 9 Schematic diagram of yet another first wall provided by an embodiment of the present application.

[0048] Icons: Vehicle 1000, Battery 100, Controller 200, Motor 300, Box 10, Battery Cell 20, First Sub-box 11, Second Sub-box 12, Outer Shell 21, Electrode Assembly 22, Electrode Terminal 25, Housing 211, Bottom Wall 211a, Peripheral Side Wall 211b, Cover Plate 212, First Wall 212a, Pressure Relief Notch 201, Arc Segment 201a, First Extension Segment 201b, Second Extension Segment 201c, Central Axis 202, Opening 203, First Edge 204, Second Edge 205. Detailed Embodiments

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0050] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs; the terms used in the description of the present application in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the description and claims of the present application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of the present application or the above drawings are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship.

[0051] References to "embodiments" in this application mean that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment each time, nor are they independent or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described in this application can be combined with other embodiments.

[0052] In the description of this application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "coupled", and "attached" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0053] The term "and / or" in this application is merely a description of the association relationship of associated objects, indicating that there can be three relationships. 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 represents an "or" relationship between the associated objects before and after.

[0054] The term "a plurality of" as used in this application refers to two or more (including two). Similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of sheets" refers to two or more sheets (including two sheets).

[0055] In some embodiments, the battery can be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0056] In some embodiments, the battery can be a battery pack. The battery pack includes a box body and battery cells, and the battery cells or battery modules are accommodated in the box body.

[0057] In some embodiments, the box body can be part of the chassis structure of a vehicle. For example, part of the box body can become at least part of the floor of the vehicle, or part of the box body can become at least part of the cross beams and longitudinal beams of the vehicle.

[0058] In some embodiments, the battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0059] In the embodiments of this application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging so as to continue to be used.

[0060] The battery cell can be, but is not limited to, a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid battery, etc.

[0061] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are intercalated and deintercalated back and forth between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, which can prevent the short circuit between the positive and negative electrodes and at the same time allow the active ions to pass through.

[0062] In some embodiments, the positive electrode can be a positive electrode sheet, and the positive electrode sheet can include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0063] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0064] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum with silver plating on the surface, stainless steel with silver plating on the surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as 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.).

[0065] As an example, the positive electrode active material can include at least one of the following materials: lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used.

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

[0067] As an example, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum with silver plating on the surface, stainless steel with silver plating on the surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. can be used.

[0068] In some embodiments, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0069] As an example, the negative electrode active material can be the negative electrode active material for batteries known in the art. As an example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials can be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials can be selected from at least one of elemental tin, tin oxides, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0070] In some embodiments, the separator is a separator membrane. This application has no particular limitation on the type of the separator membrane, and any well-known porous structure separator membrane with good chemical stability and mechanical stability can be selected.

[0071] As an example, the main material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. The separator membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a single component located between the positive and negative electrodes or attached to the surfaces of the positive and negative electrodes.

[0072] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive electrode and the negative electrode and simultaneously functions to transport ions and isolate the positive and negative electrodes.

[0073] In some embodiments, the battery cell further includes an electrolyte, and the electrolyte functions to conduct ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Among them, the liquid electrolyte includes electrolyte salts and solvents.

[0074] In some embodiments, the electrolyte salts can include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0075] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, 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.

[0076] Among them, the gel electrolyte includes a polymer as the skeletal network of the electrolyte, combined with an ionic liquid-lithium salt.

[0077] Among them, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0078] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, single-ion polymer, polyionic liquid-lithium salt, cellulose, etc.

[0079] As an example, the inorganic solid electrolyte may include one or more of oxide solid electrolytes (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON film), sulfide solid electrolytes (crystalline lithium superionic conductor (lithium germanium phosphorus sulfur, argyrodite), amorphous sulfide), and halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0080] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to the polymer solid electrolyte.

[0081] In some embodiments, the electrode assembly is a wound structure. The positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0082] In some embodiments, the electrode assembly is a laminated structure.

[0083] In some embodiments, the 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 shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film, etc.

[0084] In some embodiments, the outer casing includes an end cap and a housing. The housing is provided with an opening, and the end cap closes the opening to form a sealed space for accommodating substances such as an electrode assembly and an electrolyte. The housing may be provided with one or more openings. One or more end caps may also be provided.

[0085] In some embodiments, at least one electrode terminal is provided on the outer casing, and the electrode terminal is electrically connected to the tab of the electrode assembly. The electrode terminal may be directly connected to the tab or indirectly connected to the tab through an adapter. The electrode terminal may be provided on the end cap or on the housing.

[0086] In some embodiments, an explosion-proof valve is provided on the outer casing. The explosion-proof valve is used to release the internal pressure of the battery cell.

[0087] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a multi-prismatic battery, and the multi-prismatic battery is, for example, a hexagonal prism battery, etc. There is no particular limitation in the embodiments of the present application.

[0088] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide a higher voltage and capacity.

[0089] 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.

[0090] In some embodiments, the battery may be a battery pack. The battery pack includes a box body and battery cells, and the battery cells or battery modules are accommodated in the box body.

[0091] In some embodiments, the box body may be part of the chassis structure of a vehicle. For example, a part of the box body may become at least a part of the floor of the vehicle, or a part of the box body may become at least a part of the cross beam and longitudinal beam of the vehicle.

[0092] In some embodiments, the battery may be an energy storage device. The energy storage device includes an energy storage container, an energy storage electrical cabinet, etc.

[0093] The battery has outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide application range, and small self-discharge coefficient, and is an important part of the development of new energy today.

[0094] The development of battery technology needs to consider multiple design factors at the same time. For example, performance parameters such as energy density, discharge capacity, charge and discharge rate, etc. In addition, the assembly efficiency of the battery also needs to be considered.

[0095] The battery cell disclosed in the embodiments of the present application can be used in, but is not limited to, electrical equipment such as vehicles, ships, or aircraft. A power supply system of the electrical equipment can be composed of the battery cell and battery disclosed in the present application.

[0096] The embodiments of the present application provide an electrical equipment using a battery cell as a power source. The electrical equipment can be, but is not limited to, mobile phones, tablet computers, laptop computers, electric toys, electric tools, electric bicycles, electric motorcycles, electric vehicles, ships, spacecraft, etc. Among them, the electric toys can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc. The spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0097] For the convenience of description in the following embodiments, an electrical equipment of an embodiment of the present application is taken as an example of a vehicle 1000 for illustration.

[0098] Please refer to Figure 1 , Figure 1 which is a schematic diagram of the vehicle provided in the first embodiment of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, etc. A battery 100 is disposed inside the vehicle 1000. The battery 100 can be disposed at the bottom, head, or tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000. For example, the battery 100 can be used as an operating power source of the vehicle 1000 and used for the circuit system of the vehicle 1000, such as the working power consumption requirements for starting, navigating, and running of the vehicle 1000.

[0099] The vehicle 1000 can 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, it is used for the working power consumption requirements for starting, navigating, and driving of the vehicle 1000.

[0100] In some embodiments of the present application, the battery 100 can not only be used as an operating power source of the vehicle 1000, but also be used as a driving power source of the vehicle 1000 to provide driving power for the vehicle 1000 instead of or partially replacing fuel or natural gas.

[0101] Please refer to Figure 2 , Figure 2An exploded view of the battery provided by the first embodiment of the present application. The battery 100 includes a box body 10 and battery cells 20, and the battery cells 20 are accommodated in the box body 10. Among them, the box body 10 is used to provide an accommodation space for the battery cells 20, and the box body 10 can adopt various structures. In some embodiments, the box body 10 may include a first sub-box body 11 and a second sub-box body 12. The first sub-box body 11 and the second sub-box body 12 are covered with each other, and the first sub-box body 11 and the second sub-box body 12 jointly define an accommodation space for accommodating the battery cells 20. The second sub-box body 12 may be a hollow structure with one end open, and the first sub-box body 11 may be a plate-like structure. The first sub-box body 11 covers the open side of the second sub-box body 12 so that the first sub-box body 11 and the second sub-box body 12 jointly define an accommodation space; the first sub-box body 11 and the second sub-box body 12 may also both be hollow structures with one side open, and the open side of the first sub-box body 11 covers the open side of the second sub-box body 12.

[0102] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 can be connected in series, in parallel, or in a mixed connection. A mixed connection means that there are both series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed connection together, and then the whole formed by the multiple battery cells 20 is accommodated in the box body 10; of course, the battery 100 can also be that multiple battery cells 20 are first connected in series, in parallel, or in a mixed connection to form a battery module form, and then multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole and are accommodated in the box body 10. The battery 100 may further include other structures. For example, the battery 100 may further include a busbar component for realizing the electrical connection between the multiple battery cells 20.

[0103] Among them, the battery cell 20 can be a secondary battery or a primary battery; the battery cell 20 can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto.

[0104] Please refer to Figure 3 , Figure 3 An exploded view of the battery cell provided by some embodiments of the present application. As Figure 3 shown, the battery cell 20 includes a housing 21, an electrode assembly 22, and an electrode terminal 25. The housing 21 includes a case 211 and a cover plate 212. The case 211 has an opening, and the cover plate 212 closes the opening to isolate the internal environment of the battery cell 20 from the external environment.

[0105] The housing 211 is a component for cooperating with the cover plate 212 to form the internal environment of the battery cell 20. Among them, the formed internal environment can be used to accommodate the electrode assembly 22, the electrolyte, and other components. The housing 211 and the cover plate 212 can be independent components. The housing 211 can be of various shapes and sizes. Specifically, the shape of the housing 211 can be determined according to the specific shape and size of the electrode assembly 22. The material of the housing 211 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0106] The cover plate 212 is a component that covers the opening of the housing 211 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the cover plate 212 can be adapted to the shape of the housing 211 to cooperate with the housing 211. Optionally, the cover plate 212 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the cover plate 212 is not easily deformed when subjected to extrusion and collision, enabling the battery cell 20 to have higher structural strength and improved reliability. Functional components such as electrode terminals can be provided on the cover plate 212. The electrode terminals can be used to electrically connect to the electrode assembly 22 for outputting or inputting the electrical energy of the battery cell 20. The material of the cover plate 212 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special limitations on this. In some embodiments, an insulating structure can also be provided on the inner side of the cover plate 212, and the insulating structure can be used to isolate the electrical connection components in the housing 211 from the cover plate 212 to reduce the risk of short circuit. Exemplarily, the insulating structure can be plastic, rubber, etc.

[0107] The electrode assembly 22 is a component in the battery cell 20 where an electrochemical reaction occurs. The housing 211 can contain one or more electrode assemblies 22. The electrode assembly 22 is mainly formed by winding or laminating a positive electrode plate and a negative electrode plate, and usually an isolation film is provided between the positive electrode plate and the negative electrode plate to separate the positive electrode plate and the negative electrode plate to prevent internal short circuit between the positive electrode plate and the negative electrode plate. The parts of the positive electrode plate and the negative electrode plate with active substances constitute the main body of the electrode assembly, and the parts of the positive electrode plate and the negative electrode plate without active substances respectively constitute the electrode tabs. The positive electrode tab and the negative electrode tab can be located at one end of the main body together or at both ends of the main body respectively. During the charge and discharge process of the battery, the positive active substance and the negative active substance react with the electrolyte, and the electrode tabs are connected to the electrode terminals to form a current loop.

[0108] In the existing technical solutions, the pressure relief notch is provided on the outer shell of the battery cell. Generally, the pressure relief notch is provided on the side surface of the outer shell in the thickness direction and does not penetrate the outer shell in the thickness direction of the outer shell, so that the structural strength of the part of the outer shell provided with the pressure relief notch is relatively low. When the battery cell undergoes thermal runaway, due to the rapid increase in the pressure inside the outer shell in a short period of time, the area where the pressure relief notch is located will be torn first.

[0109] However, since the existing pressure relief notch has no guiding effect, the tearing range and tearing direction of the crack during the tearing process of the pressure relief notch are uncontrollable. For example, the pressure relief notch is located in the central area of the side wall of the outer shell. When the battery cell undergoes thermal runaway, the crack will not be guided to the preset position, but extends in an irregular direction away from the central area, and multiple cracks diverge away from the central area, damaging most of the area of the side wall where the pressure relief notch is located; or the pressure relief notch is provided in the corner area of the side wall of the outer shell. When the battery cell undergoes thermal runaway, the crack may extend towards the central area of the side wall, thereby damaging most of the area of the side wall. Therefore, due to the lack of guiding effect of the existing pressure relief notch, the crack will cause extensive damage to the outer shell, affecting the recycling of the outer shell.

[0110] In addition, due to the uncontrollable tearing range and tearing direction of the crack, the high-pressure gas will be discharged disorderly from the crack, which may cause damage to other battery cells.

[0111] For this reason, the present application proposes a battery cell. After the battery undergoes thermal runaway, the tearing direction or tearing range of the pressure relief notch on the battery cell is controllable, so that local valve opening can be achieved.

[0112] Such as Figure 4 And as Figure 6 As shown, the battery cell 20 according to an embodiment of the present application may include an outer shell 21 and a pressure relief notch 201.

[0113] The outer shell 21 can isolate the external environment and the internal environment of the battery cell 20. The outer shell 21 can be a metal part, and of course it can also be an insulating part.

[0114] The outer shell 21 can define an accommodation space, and an electrode assembly 22 and an electrolyte for infiltrating the electrode assembly can be accommodated in the accommodation space.

[0115] The outer shell 21 can include a first wall 212a. The first wall 212a can be one of the walls of the outer shell 21. The present application does not limit the specific position or specific function of the first wall 212a on the outer shell 21. For example, the first wall 212a can be the wall of the outer shell 21 provided with electrode terminals, or the outer shell 21 can be a flat structure, and the first wall 212a is one of the walls of the outer shell 21 in the thickness direction.

[0116] The pressure relief notch 201 is provided on the first wall 212a. Generally, the pressure relief notch 201 is provided on the side surface of the first wall 212a in the thickness direction. For example, the pressure relief notch 201 can be provided on the inner side surface and / or the outer side surface of the first wall 212a.

[0117] The pressure relief notch 201 can be formed on the first wall 212a by laser etching, and the pressure relief notch 201 does not penetrate the first wall 212a in the thickness direction of the first wall 212a.

[0118] The structural strength of the part of the first wall where the pressure relief notch 201 is provided is smaller than that of other parts. Therefore, after the thermal runaway of the battery cell 20 occurs, the pressure relief notch will tear first, so as to quickly discharge the high-pressure gas in the housing 21.

[0119] The pressure relief notch 201 is generally of a groove structure, and the cross-sectional shape of the pressure relief notch 201 can be semicircular, trapezoidal or other shapes. The present application does not limit the specific shape of the cross-section of the pressure relief notch 201.

[0120] The pressure relief notch 201 includes an arc segment 201a. As the name implies, the arc segment 201a is not a complete circle, but an arc segment corresponding to the central angle of a certain circle. The central angle and radius of the arc segment 201a can be adjusted as needed.

[0121] The arc segment 201a has a first end, and the first end can be one end of the arc segment 201a in the length direction.

[0122] The arc segment 201a may also have a second end, and the second end can be the other end of the arc segment 201a in the length direction.

[0123] The pressure relief notch 201 further includes a first extension segment 201b. The first extension segment 201b can be a straight line segment, an arc segment or other special-shaped line segments (for example, serpentine, etc.). The specific type of the first extension segment 201b is not limited here.

[0124] The first extension segment 201b can be connected to the first end, and the first extension segment 201b can extend from the first end towards the direction close to the central axis 202 of the arc segment 201a.

[0125] It should be noted that the central axis 202 of the arc segment 201a can divide the arc segment 201a into two sub-arc segments, and the two sub-arc segments are symmetrical about the central axis 202 of the arc segment 201a.

[0126] Thus, the extension line of the first extension segment 201b extending in the direction away from the arc segment 201a will eventually intersect with the central axis 202 of the arc segment 201a.

[0127] The pressure relief notch 201 may further include a second extension section 201c, and the second extension section 201c may be a straight line section, an arc section or other special-shaped line sections (for example, serpentine, etc.), and the specific type of the second extension section 201c is not limited herein.

[0128] The second extension section 201c may be connected to the second end, and the second extension section 201c may extend from the second end towards the direction of the central axis 202 of the arc section 201a.

[0129] Thus, the extension line of the second extension section 201c extending away from the arc section 201a will eventually intersect the central axis 202 of the arc section 201a.

[0130] The first extension section 201b and the second extension section 201c may also be symmetric about the central axis 202 of the arc section 201a. Of course, the first extension section 201b and the second extension section 201c may also be asymmetric about the central axis 202 of the arc section 201a, as long as it is ensured that the first extension section 201b extends from the first end towards the direction of the central axis 202 of the arc section 201a and the second extension section 201c extends from the second end towards the direction of the central axis 202 of the arc section 201a.

[0131] According to the battery cell of the embodiment of the present application, as Figure 9 shown, the pressure relief notch may include an arc section 201a and a first extension section 201b. By extending the first extension section 201b from the first end towards the direction of the central axis 202 of the arc section, the arc section 201a can reduce the stress concentration during the processing of the pressure relief notch 201. When the battery cell 20 undergoes thermal runaway and the internal high-pressure gas tears the pressure relief notch 201, the first extension section 201b can guide the crack towards the direction of the central axis 202 of the arc section 201a, so that the size of the torn part on the outer shell 21 is controllable. Of course, the first extension section 201b can also make the tearing direction of the crack controllable. Thus, after the battery cell 20 undergoes thermal runaway and the pressure relief notch 201 is torn, local valve opening can be realized, reducing the probability of large-scale tearing of the outer shell 21. The tearing direction and tearing range of the crack are both controllable, reducing the damage to the battery cell 20 caused by the uncontrollability of the crack.

[0132] According to the battery cell 20 of the embodiment of the present application, the pressure relief notch 201 includes an arc segment 201a, a first extension segment 201b, and a second extension segment 201c. By extending the first extension segment 201b from the first end towards the direction of the central axis 202 of the arc segment 201a, and extending the second extension segment 201c from the second end towards the direction of the central axis 202 of the arc segment 201a, the arc segment 201a can reduce the stress concentration during the processing of the pressure relief notch 201. When the battery cell 20 undergoes thermal runaway and the internal high-pressure gas tears the pressure relief notch 201, the first extension segment 201b and the second extension segment 201c can guide the crack towards the direction of the central axis 202 of the arc segment 201a. Thus, the first extension segment 201b and the second extension segment 201c can guide the cracks on the outer shell 21 to gradually converge, making the size of the torn part on the outer shell 21 controllable. Of course, the first extension segment 201b and the second extension segment 201c can also make the tearing direction of the crack controllable. Therefore, after the battery cell 20 undergoes thermal runaway and the pressure relief notch 201 is torn, local valve opening can be achieved, reducing the probability of large-scale tearing of the outer shell 21. The tearing direction and tearing range of the crack are both controllable, reducing the damage caused to the battery cell 20 due to the uncontrollability of the crack, and also reducing the impact on other battery cells 20 caused by the disorderly discharge of high-pressure gas due to the uncontrollability of the crack.

[0133] According to some embodiments of the present application, the first extension segment 201b and the second extension segment 201c are symmetrical about the central axis 202. For example, the extension length of the first extension segment 201b is the same as that of the second extension segment 201c. If both the first extension segment 201b and the second extension segment 201c are straight lines, the angle between the extension line of the first extension segment 201b and the central axis 202 is the same as the angle between the extension line of the second extension segment 201c and the central axis 202. Thus, the tearing direction and tearing range of the crack guided by the first extension segment 201b and the second extension segment 201c can be kept substantially the same, reducing the probability of uncontrollability of the crack, and further achieving stable local valve opening of the outer shell 21.

[0134] According to some embodiments of the present application, the length of the first extension segment 201b is the same as that of the second extension segment 201c. It should be noted that both the first extension segment 201b and the second extension segment 201c can be straight line segments, or both the first extension segment 201b and the second extension segment 201c can be arc segments, or one of the first extension segment 201b and the second extension segment 201c is an arc segment and the other is a straight line segment. As long as the length of the first extension segment 201b is the same as that of the second extension segment 201c, it is within the protection scope of the present application.

[0135] Thus, the valve-opening area of the crack at the first extended section 201b is substantially the same as that of the crack at the second extended section 201c, and the subsequent valve-opening area of the housing 21 after the crack is guided by the first extended section 201b is also substantially the same as that after the crack is guided by the second extended section 201c, thereby ensuring the stability of the tearing range of the crack and reducing the uncontrollable probability of the crack.

[0136] According to some embodiments of the present application, both the first extended section 201b and the second extended section 201c are straight line segments, and the angle between the extension line of the first extended section 201b and the central axis 202 is the same as the angle between the extension line of the second extended section 201c and the central axis 202. Thus, the cracks guided by the first extended section 201b and the second extended section 201c can intersect on the central axis 202, thereby realizing local valve opening of the housing 21.

[0137] According to some embodiments of the present application, the length of the first extended section 201b is less than that of the second extended section 201c. After the crack is guided by the first extended section 201b, it will continue to tear the housing 21. Similarly, after the crack is guided by the second extended section 201c, it will continue to tear the housing 21. Since the length of the first extended section 201b is less than that of the second extended section 201c, without the guidance of the first extended section 201b and the second extended section 201c, the subsequent valve-opening area of the housing 21 after the crack is guided by the first extended section 201b is larger than that after the crack is guided by the second extended section 201c. Thus, after the battery cell 20 undergoes thermal runaway, the high-pressure gas in the housing 21 can be quickly discharged.

[0138] According to some embodiments of the present application, both the first extended section 201b and the second extended section 201c are straight line segments, and the angle between the extension line of the first extended section 201b and the central axis 202 is different from the angle between the extension line of the second extended section 201c and the central axis 202. Thus, the subsequent valve-opening area of the housing 21 after the crack is guided by the first extended section 201b is different from that after the crack is guided by the second extended section 201c, and at least one of the subsequent valve-opening areas of the housing 21 after the crack is guided by the first extended section 201b and the second extended section 201c is larger. Thus, after the battery cell 20 undergoes thermal runaway, the high-pressure gas in the housing 21 can be quickly discharged.

[0139] In some embodiments of the present application, such as Figure 4As shown, the central angle of the arc segment 201a is α, satisfying: 180° ≤ α < 360°. For example, the central angle can be 180°, 200°, 220°, 240°, 260°, 280°, 300°, 320°, 340°, 350°.

[0140] This application does not limit the specific value of the central angle of the arc segment 201a, as long as it is ensured that the central angle of the arc segment 201a is within the above range.

[0141] When α ≥ 180°, the area enclosed by the arc segment 201a is sufficient. Thus, when the battery cell 20 undergoes thermal runaway, the crack tears the outer shell 21 along the arc segment 201a, and the crack on the arc segment 201a can enable the high-pressure gas inside the outer shell 21 to be quickly discharged; when α < 360°, the pressure relief notch 201 is an unclosed annular structure, and there is an opening on the pressure relief notch 201. Thus, the crack can tear the outer shell along the direction of the opening, making the tearing direction and range of the crack controllable, and further realizing local valve opening of the crack on the outer shell 21. When 180° ≤ α < 360°, it can not only make the range of the crack torn along the arc segment 201a sufficient and the high-pressure gas inside the outer shell 21 can be quickly discharged, but also there is an opening on the pressure relief notch 201, which can guide the tearing direction and range of the crack, realizing local valve opening of the crack on the outer shell 21.

[0142] Since the central angle of the arc segment 201a satisfies the above range, the range of the pressure relief notch 201 is sufficient and can be opened when the pressure inside the outer shell 21 meets the preset conditions, and at the same time, there will be no situation where the crack extends randomly after the circular pressure relief notch 201 is torn.

[0143] In addition, the tangents at both ends of the arc segment 201a in the length direction can also be parallel or intersect, so that the arc segment 201a itself can also guide the cracks at the first end and the second end to extend towards each other, and the extending directions of the cracks on both sides are in a converging state, making the tearing direction and range of the crack controllable.

[0144] In some embodiments of this application, 210° ≤ α ≤ 330°. For example, the central angle α of the arc segment 201a can be 210°, 240°, 245°, 250°, 255°, 260°, 265°, 270°, 275°, 280°, 285°, 290°, 295°, 300°, 330°.

[0145] When α≥210°, the enclosed area of the arc segment 201a is further increased. Thus, when the battery cell 20 undergoes thermal runaway, the crack tears the outer shell 21 along the arc segment 201a, and the tearing range of the crack allows the high-pressure gas inside the outer shell 21 to be discharged more quickly; when α≤330°, the pressure relief notch 201 is an unclosed annular structure with an opening and a larger opening range on the pressure relief notch 201. Thus, the crack can tear the outer shell along the orientation of the opening. Not only is the tearing direction and tearing range of the crack controllable, but also the tearing range of the crack is larger. Furthermore, the high-pressure gas inside the outer shell 21 can be discharged more quickly. When 210°≤α≤330°, the discharge speed of the high-pressure gas inside the outer shell 21 can be further increased. At the same time, the opening size on the arc segment 201a is larger, so that the crack can be guided to have a larger tearing range in the outer shell 21. Thus, the opening can not only guide the tearing direction and tearing range of the crack, but also further increase the discharge speed of the high-pressure gas inside the outer shell 21.

[0146] Since the central angle of the arc segment 201a satisfies the above range, the range of the pressure relief notch 201 is sufficient and can be opened when the pressure inside the outer shell 21 meets the preset conditions. At the same time, the tangents at both ends of the arc segment 201a in the length direction can also intersect. Thus, the arc segment 201a itself can also guide the cracks at the first end and the second end to extend towards each other, and the extending directions of the cracks on both sides are in a converging state, so that the extending direction and tearing range of the crack are controllable.

[0147] In some embodiments of the present application, the first extension segment 201b can be tangent to the arc segment 201a. That is to say, the first extension segment 201b coincides with the tangent at the first end. Thus, the crack on the arc segment 201a can very smoothly extend and tear along the tangent at the first end of the arc segment 201a, reducing the obstruction during the crack tearing process, making the crack tearing smoother and controllable, and reducing the stress concentration during the tearing process.

[0148] It can be understood that the first extension segment 201b can be an arc segment or a straight line segment. The present application does not limit the line type of the first extension segment 201b, as long as the first extension segment 201b is tangent to the arc segment 201a.

[0149] In some embodiments of the present application, as Figure 5 shown, the second extension segment 201c can be tangent to the arc segment 201a. That is to say, the second extension segment 201c coincides with the tangent at the second end. Thus, the crack on the arc segment 201a can very smoothly extend and tear along the tangent at the second end of the arc segment 201a, reducing the obstruction during the crack tearing process, making the crack tearing smoother and controllable, and reducing the stress concentration during the tearing process.

[0150] It can be understood that the second extended section 201c can be an arc segment or a straight segment. The present application does not limit the type of the line segment of the second extended section 201c, as long as it is ensured that the second extended section 201c is tangent to the arc segment 201a.

[0151] As Figure 8 shown, the first extended section 201b is an arc segment and the first extended section 201b can be tangent to the arc segment 201a, and the second extended section 201c is an arc segment and the second extended section 201c can be tangent to the arc segment 201a.

[0152] According to some embodiments of the present application, as Figure 5 shown, the first extended section 201b is a straight segment. Constructing the first extended section 201b as a straight segment can, on the one hand, make the processing of the first extended section 201b easier, and on the other hand, the tearing process of the crack on the straight segment is smoother. Or rather, the straight segment can better guide the crack to tear along the preset direction, so that the tearing direction and tearing range of the crack are more controllable.

[0153] According to some embodiments of the present application, the second extended section 201c is a straight segment. Constructing the second extended section 201c as a straight segment can, on the one hand, make the processing of the second extended section 201c easier, and on the other hand, the tearing process of the crack on the straight segment is smoother. Or rather, the straight segment can better guide the crack to tear along the preset direction, so that the tearing direction and tearing range of the crack are more controllable.

[0154] In some embodiments of the present application, as Figure 4 shown, the radius of the arc segment 201a is R, satisfying: 1mm ≤ R ≤ 20mm.

[0155] For example, the radius of the arc segment 201a can be 1mm, 3mm, 5mm, 7mm, 9mm, 11mm, 13mm, 15mm, 17mm, 19mm, 20mm.

[0156] The present application does not limit the specific value of the radius of the arc segment 201a. As long as the radius of the arc segment 201a is within the above range, it is within the protection scope of the present application.

[0157] When R ≥ 1mm, after the crack tears along the arc segment 201, the pressure relief requirement of the battery cell 20 during thermal runaway can be satisfied; when R ≤ 20mm, the range of the arc segment 201 is not too large, so that the overall structural strength of the housing 21 meets the requirements. When 1mm ≤ R ≤ 20mm, it can not only meet the pressure relief requirement of the battery cell 20 during thermal runaway, but also make the range of the pressure relief notch 201 not too large and the overall structural strength of the housing 21 meet the requirements.

[0158] In some embodiments of the present application, as Figure 4 shown, the length of the straight line segment is L 1 , satisfying: 0 < L 1 ≤ 20 mm. For example, the length of the straight line segment can be 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, 11 mm, 13 mm, 15 mm, 17 mm, 19 mm, 20 mm.

[0159] It should be noted that the length of the straight line segment is the length when the first extended segment 201b is constructed as a straight line, or the length when the second extended segment 201c is a straight line.

[0160] The present application does not limit the length of the straight line segment. As long as the radius of the straight line segment is within the above range, it is within the protection scope of the present application.

[0161] When L 1 > 0, after the crack tears along the straight line segment, it can meet the pressure relief requirement of the battery cell 20 during thermal runaway; when L 1 ≤ 20 mm, the range of the straight line segment is not too large, so that the overall structural strength of the housing 21 meets the requirements. When 0 < L 1 ≤ 20 mm, it can not only meet the pressure relief requirement of the battery cell 20 during thermal runaway, but also make the range of the pressure relief notch 201 not too large to affect the overall structural strength of the housing 21.

[0162] According to some embodiments of the present application, 3 mm ≤ R ≤ 10 mm, 1 mm ≤ L 1 ≤ 10 mm.

[0163] For example, the radius of the arc segment 201a can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm.

[0164] The present application does not limit the specific value of the radius of the arc segment 201a. As long as the radius of the arc segment 201a is within the above range, it is within the protection scope of the present application.

[0165] When R ≥ 3 mm, after the crack tears along the arc segment 201, it can further meet the pressure relief requirement of the battery cell 20 during thermal runaway; when R ≤ 10 mm, the range of the arc segment 201 is not too large, so that the overall structural strength of the housing 21 can be further satisfied. When 3 mm ≤ R ≤ 10 mm, it can not only further meet the pressure relief requirement of the battery cell 20 during thermal runaway, but also make the range of the pressure relief notch 201 not too large and the overall structural strength of the housing 21 can further meet the requirements.

[0166] For example, the length of the straight line segment can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm.

[0167] It should be noted that the length of the straight line segment is the length when the first extended segment 201b is constructed as a straight line, or the length when the second extended segment 201c is a straight line.

[0168] This application does not limit the length of the straight line segment. As long as the radius of the straight line segment is within the above range, it is within the protection scope of this application.

[0169] When L 1 ≥1mm, after the crack tears along the straight line segment, it can further meet the pressure relief requirement of the battery cell 20 during thermal runaway; when L 1 ≤10mm, the range of the straight line segment is not too large, so that the overall structural strength of the housing 21 can further meet the requirements. When 1mm ≤ L 1 ≤20mm, it can not only further meet the pressure relief requirement of the battery cell 20 during thermal runaway, but also make the range of the pressure relief notch 201 not too large, and the overall structural strength of the housing 21 can further meet the requirements.

[0170] In some embodiments of this application, 0 < L 1 / R ≤ 2. For example, L 1 / R can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0.

[0171] This application does not limit the specific value of L 1 / R. As long as L 1 / R is within the above range, it is within the protection scope of this application.

[0172] L 1 / R represents the degree of radius extension of the straight line segment relative to the arc segment. The larger L 1 / R is, the more the radius of the straight line segment extends compared to the arc segment. The smaller L 1 / R is, the less the radius of the straight line segment extends compared to the arc segment.

[0173] When L 1 / R > 0, the straight line segment can extend from one end of the arc segment. The straight line segment can guide the crack to tear the housing 21. After the crack tears along the straight line segment, it can meet the pressure relief requirement of the battery cell 20 during thermal runaway; when L 1 / R ≤ 2, so that the length of the straight line segment is not too long, thereby controlling the range of the pressure relief notch 201, so that the overall structural strength of the outer casing 21 meets the requirements. When 0 < L 1 / R ≤ 0.6, it can not only ensure that the straight line segment has enough length to guide the tearing direction and range of the crack, but also alleviate the excessive negative impact on the structural strength of the outer casing 21 due to the too long extension of the straight line segment resulting in too large a range of the pressure relief notch 201.

[0174] In some embodiments of the present application, 0.1 ≤ L 1 / R ≤ 1. For example, L 1 / R can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.7, 0.8, 0.9, 1.0.

[0175] When L 1 / R ≥ 0.1, the straight line segment can extend from one end of the arc segment, and the straight line segment can guide the crack to tear the outer casing 21. After the crack tears along the straight line segment, it can further meet the pressure relief requirement of the battery cell 20 during thermal runaway; when L 1 / R ≤ 1, so that the length of the straight line segment is not too long, thereby controlling the range of the pressure relief notch 201, so that the overall structural strength of the outer casing 21 further meets the requirements. When 0 < L 1 / R ≤ 0.6, it can not only ensure that the straight line segment has enough length to guide the tearing direction and range of the crack, but also further alleviate the excessive negative impact on the structural strength of the outer casing 21 due to the too long extension of the straight line segment resulting in too large a range of the pressure relief notch 201.

[0176] In some embodiments of the present application, as Figure 4 and Figure 5 shown, one end of the first extension segment 201b away from the arc segment 201a and one end of the second extension segment 201c away from the arc segment 201a are spaced apart to form an opening 203. That is to say, one end of the first extension segment 201b away from the arc segment 201a and one end of the second extension segment 201c away from the arc segment 201a are not connected to each other, so as to ensure that the pressure relief notch 201 is in an unclosed state.

[0177] Generally speaking, the orientation of the opening 203 directly affects the tearing direction of the crack. For example, if the opening 203 faces the corner of the first wall 212a, then after the battery cell 20 is in thermal runaway, the high-pressure gas will tear the pressure relief notch 201, and the crack can tear along the direction of the opening 203 facing the corner, so that the tearing direction of the crack can be adjusted by adjusting the orientation of the opening 203.

[0178] In some embodiments of the present application, asFigure 3 As shown, the outer shell 21 is flat, and the first wall 212a is the wall of the outer shell 21 in the thickness direction. That is to say, the pressure relief notch 201 in the embodiments of the present application will not be provided on the small surface, but on the large surface of the outer shell 21. Thus, the pressure relief notch 201 will not be restricted by the size of the small surface, and the pressure relief notch 201 can be designed to a suitable size according to needs. In addition, setting the pressure relief notch 201 on the large surface can also reduce the processing difficulty of the pressure relief notch 201, so that the manufacturing cost of the pressure relief notch 201 is reduced.

[0179] In some embodiments of the present application, as Figure 6 shown, the pressure relief notch 201 is provided in the corner area of the first wall 212a. When the pressure relief notch 201 is provided in the corner area of the first wall 212a, when the battery cell 20 undergoes thermal runaway, the crack can tear the outer shell 21 under the guidance of the pressure relief notch 201. Since the pressure relief notch 201 is provided in the corner area of the first wall 212a, the tearing area of the crack also mainly concentrates in the corner area of the first wall 212a. Thus, the probability of the crack damaging other areas of the first wall 212a can be reduced, making it possible to recycle the outer shell 21 after the battery cell 20 undergoes thermal runaway.

[0180] In some embodiments of the present application, the opening 203 on the pressure relief notch 201 faces the corner of the first wall 212a. Thus, when the crack tears the outer shell 21 along the pressure relief notch 201, it can tear along the orientation of the opening 203, that is, the tearing direction of the crack faces the corner of the first wall 212a. Thus, the probability of the crack moving towards the middle area of the first wall 212a is reduced, and the probability of the first wall 212a being completely torn is reduced, making it possible to recycle the outer shell 21.

[0181] According to some embodiments of the present application, as Figure 6 shown, the first wall 212a includes a first edge 204 and a second edge 205, and the first edge 204 and the second edge 205 intersect to form a corner of the first wall 212a.

[0182] The shortest distance between the center of the pressure relief notch 201 and the first edge 204 is L 2 , and the length of the second edge 205 is L, satisfying: 0 < L 2 < L / 2;

[0183] The shortest distance between the center of the pressure relief notch 201 and the second edge 205 is W 1 , and the length of the first edge 204 is W, satisfying: 0 < W 1 < W / 2.

[0184] Thus, the center of the pressure relief notch 201 is close to a corner defined by the first edge 204 and the second edge 205. Consequently, the tearing area of the crack is also mainly concentrated in the corner area of the first wall 212a, thereby reducing the probability of damage to other areas of the first wall 212a. This makes it possible to recycle the outer shell 21 after the battery cell 20 undergoes thermal runaway.

[0185] In some embodiments of the present application, as Figure 6 shown, the shortest distance between the end of the first extension segment 201b away from the arc segment 201a and the first edge 204 is L 3 , the length of the second edge 205 is L, satisfying: 0 < L 3 < L / 2; the shortest distance between the end of the second extension segment 201c away from the arc segment 201a and the second edge 205 is W 2 , the length of the first edge 204 is W, satisfying: 0 < W 2 < W / 2.

[0186] The end of the first extension segment 201b away from the arc segment 201a and the end of the second extension segment 201c away from the arc segment 201a are spaced apart to form an opening 203. Since the shortest distance between the end of the first extension segment 201b away from the arc segment 201a and the first edge 204 and the length of the second edge 205 satisfy the above conditions, and the shortest distance between the end of the second extension segment 201c away from the arc segment 201a and the second edge 205 and the length of the first edge 204 satisfy the above conditions, the opening 203 faces the corner defined by the first edge 204 and the second edge 205.

[0187] Thus, when the crack tears the outer shell 21 along the pressure relief notch 201, it can tear along the orientation of the opening 203, that is, the tearing direction of the crack faces the corner of the first wall 212a, thereby reducing the probability of the crack moving towards the middle area of the first wall 212a and reducing the probability of the first wall 212a being completely torn, making it possible to recycle the outer shell 21.

[0188] In the related art, the pressure relief notch is configured as a ring and is located in the central area of the first wall. Since there is no opening on the pressure relief notch, when the battery cell undergoes thermal runaway, the crack is not guided to a preset position but extends in a direction away from the central area irregularly. Multiple cracks diverge away from the central area, damaging most of the area of the first wall.

[0189] In some embodiments of the present application, as Figure 4As shown, the pressure relief notch 201 is provided in the central region of the first wall 212a. It can be understood that the center of the pressure relief notch 201 can be provided in the central region of the first wall 212a, or the region surrounded by the pressure relief notch 201 can be located in the central region of the first wall 212a.

[0190] The pressure relief notch 201 is provided in the central region of the first wall 212a. At the same time, since the pressure relief notch 201 has an opening 203, when the battery cell 20 undergoes thermal runaway, the crack will extend along the pressure relief notch 201 and extend along the region towards the opening 203. Therefore, the crack will not tear randomly and will not damage most of the region of the first wall 212a, but can be guided to a preset region.

[0191] In some embodiments of the present application, as Figure 7 shown, the thickness of the first wall 212a is T, satisfying: 0.03 mm ≤ T ≤ 0.6 mm. For example, the thickness of the first wall 212a provided with the pressure relief notch 201 can be 0.03 mm, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm. The present application does not limit the specific value of the thickness of the first wall 212a, as long as the thickness of the first wall 212a satisfies the above range, it is within the protection scope of the present application.

[0192] When T ≥ 0.03 mm, it can ensure that the first wall 212a has sufficient structural strength, which is convenient for laser etching the pressure relief notch 201 thereon later; when T ≤ 0.6 mm, it can make the first wall 212a thin enough to improve the energy density of the battery cell 20 in the thickness direction of the first wall 212a. When 0.03 mm ≤ T ≤ 0.6 mm, it can not only ensure that the first wall 212a is thin enough to improve the energy density of the battery cell 20 in the thickness direction of the first wall 212a, but also make the first wall 212a have sufficient structural strength, which is convenient for laser etching the pressure relief notch 201 thereon later.

[0193] In some embodiments of the present application, as Figure 7As shown, the first wall 212a is provided with a pressure relief notch 201, and the thickness of the first wall 212a is T, satisfying: 0.05 mm ≤ T ≤ 0.2 mm. For example, the thickness of the first wall 212a provided with the pressure relief notch 201 can be 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm. The present application does not limit the specific value of the thickness of the first wall 212a, as long as the thickness of the first wall 212a satisfies the above range, it is within the protection scope of the present application.

[0194] When T ≥ 0.05 mm, it can further ensure that the first wall 212a has sufficient structural strength, facilitating subsequent laser etching of the pressure relief notch 201 thereon; when T ≤ 0.2 mm, the first wall 212a can be made thin enough to further improve the energy density of the battery cell 20 in the thickness direction of the first wall 212a. When 0.03 mm ≤ T ≤ 0.6 mm, it can not only ensure that the first wall 212a is thin enough to further improve the energy density of the battery cell 20 in the thickness direction of the first wall 212a, but also make the first wall 212a further have sufficient structural strength, facilitating subsequent laser etching of the pressure relief notch 201 thereon.

[0195] In some embodiments of the present application, the outer shell 21 includes a housing 211 and a cover plate 212. The housing 211 includes a bottom wall 211a and a peripheral side wall 211b. One end of the peripheral side wall 211b is connected to the outer peripheral edge of the bottom wall 211a, and the other end of the peripheral side wall 211b encloses a first opening. The cover plate 212 closes the first opening, wherein the first wall 212a is the cover plate 212 or the bottom wall 211a.

[0196] That is to say, the outer shell 21 is jointly formed by two separate components - the housing 211 and the cover plate 212. The housing 211 and the cover plate 212 can be metal parts, and the two can be fixed together by welding. The first wall 212a is the cover plate 212 or the bottom wall 211a. Therefore, the pressure relief notch 201 is provided on the cover plate 212 or the bottom wall 211a. For example, if the battery cell 20 is flat and the cover plate 212 and the bottom wall 211a are opposite in the thickness direction, the pressure relief notch 201 is provided on the large surface of the outer shell 21.

[0197] In some embodiments of the present application, the outer shell 21 is made of stainless steel, and the pressure relief notch 201 can be processed and formed by laser etching. Of course, the pressure relief notch 201 can also be formed by stamping. The present application does not limit the forming method of the pressure relief notch 201.

[0198] In some embodiments of the present application, the cross-sectional shape of the pressure relief notch 201 may be trapezoidal. Among the two parallel sides of the trapezoid, the longer side is located at the opening 203 of the groove of the pressure relief notch 201. The length of the shorter side among the two parallel sides may be 0.05 mm - 1.0 mm, and the bottom angle of the trapezoid (the angle between the bottom wall and the peripheral wall of the trapezoidal groove) may be 30° - 60°.

[0199] The cross-section of the pressure relief notch 201 is trapezoidal, with better consistency and less stress concentration. Of course, the cross-section of the pressure relief notch 201 may also be triangular, arc-shaped or rectangular.

[0200] The battery of the embodiment of the present application will be briefly described below.

[0201] The battery according to the embodiment of the present application includes the battery cell 20 of the above embodiment. Since the battery according to the embodiment of the present application is provided with the above battery cell 20, the pressure relief notch 201 can be torn when the battery cell 20 is in thermal runaway. The size and tearing direction of the torn part on the outer shell 21 are controllable, realizing local valve opening and reducing the probability of tearing the outer shell 21 on a large scale.

[0202] The electrical equipment of the embodiment of the present application will be briefly described below.

[0203] The electrical equipment according to the embodiment of the present application includes the above battery. Since the electrical equipment according to the embodiment of the present application is provided with the above battery, the safety of the electrical equipment is improved, and the negative impact of the battery cell 20 on the electrical equipment during thermal runaway is reduced.

[0204] Although the present application has been described with reference to the preferred embodiments, various improvements can be made to it and components therein can be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, it includes: a housing including a first wall; a pressure relief indentation provided on the first wall, the pressure relief indentation including an arc segment and a first extension segment, the arc segment having a first end, and the first extension segment being connected to the first end and extending from the first end towards the direction close to the central axis of the arc segment.

2. The battery cell according to claim 1, characterized in that, the pressure relief indentation further includes a second extension segment, the arc segment having a second end, and the second extension segment being connected to the second end and extending from the second end towards the direction close to the central axis.

3. The battery cell according to claim 2, characterized in that, the first extension segment and the second extension segment are symmetrical about the central axis.

4. The battery cell according to claim 2, characterized in that, the length of the first extension segment is the same as the length of the second extension segment.

5. The battery cell according to claim 2, characterized in that, both the first extension segment and the second extension segment are straight line segments, and the angle between the extension line of the first extension segment and the central axis is the same as the angle between the extension line of the second extension segment and the central axis.

6. The battery cell according to claim 2, characterized in that, the length of the first extension segment is less than the length of the second extension segment.

7. The battery cell according to claim 2, characterized in that, both the first extension segment and the second extension segment are straight line segments, and the angle between the extension line of the first extension segment and the central axis is not the same as the angle between the extension line of the second extension segment and the central axis.

8. The battery cell according to claim 1, characterized in that, the central angle of the arc segment is α, satisfying: 180° ≤ α < 360°.

9. The battery cell according to claim 8, characterized in that, 210°≤α≤330°。 10. The battery cell according to claim 1, characterized in that, the first extension segment is tangent to the arc segment; and / or the second extension segment is tangent to the arc segment.

11. The battery cell according to claim 1, characterized in that, the first extension segment is a straight line segment; and / or the second extension segment is a straight line segment.

12. The battery cell according to claim 11, characterized in that, the radius of the arc segment is R, satisfying: 1 mm ≤ R ≤ 20 mm; The length of the straight line segment is L 1 , satisfying: 0 < L 1 ≤ 20 mm.

13. The battery cell according to claim 12, characterized in that, 3mm ≤ R ≤ 10mm, 1mm ≤ L 1 ≤ 10mm.

14. The battery cell according to claim 11 or 12, characterized in that, Satisfy: 0 < L 1 / R ≤ 2.

15. The battery cell according to claim 14, characterized in that, Satisfy: 0.1 ≤ L 1 / R ≤ 1.

16. The battery cell according to claim 1, characterized in that, the ends of the first extension segment far from the arc segment and the ends of the second extension segment far from the arc segment are spaced apart to form an opening.

17. The battery cell according to claim 16, characterized in that, the housing is flat, and the first wall is the wall of the housing in the thickness direction.

18. The battery cell according to claim 17, characterized in that, The pressure relief notch is provided in the corner area of the first wall and the opening faces the corner of the first wall.

19. The battery cell according to claim 17, wherein, the first wall includes a first edge and a second edge, and the first edge and the second edge intersect to form a corner of the first wall; The shortest distance between the center of the pressure relief notch and the first edge is L 2 , the length of the second edge is L, and it satisfies: 0 < L 2 < L / 2; The shortest distance between the center of the pressure relief notch and the second edge is W 1 , the length of the first edge is W, satisfying: 0 < W 1 < W / 2.

20. The battery cell according to claim 17, wherein, The shortest distance between one end of the first extension section, which is far from the arc section, and the first edge is L 3 , the length of the second edge is L, and it satisfies: 0 < L 3 < L / 2; The shortest distance between one end of the second extension section, which is far from the arc section, and the second edge is W 2 , the length of the first edge is W, satisfying: 0 < W 2 < W / 2.

21. The battery cell according to claim 17, wherein, the pressure relief notch is provided in the central area of the first wall.

22. The battery cell according to claim 1, wherein, the wall thickness of the first wall is T, satisfying: 0.03 mm ≤ T ≤ 0.6 mm.

23. The battery cell according to claim 22, wherein, the T satisfies: 0.05 mm ≤ T ≤ 0.2 mm.

24. The battery cell according to claim 1, wherein, the housing includes a casing and a cover plate. The casing includes a bottom wall and a peripheral side wall. One end of the peripheral side wall is connected to the outer peripheral edge of the bottom wall, and the other end of the peripheral side wall encloses a first opening. The cover plate closes the first opening; wherein the first wall is the cover plate or the bottom wall.

25. A battery, wherein, it includes the battery cell according to any one of claims 1-24.

26. An electrical device, wherein, it includes the battery cell according to any one of claims 1-24 or the battery according to claim 25, and the battery cell or the battery is used to provide electrical energy.

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