Battery cell, battery, and electrical device

Abstract

A battery cell (20), a battery (100), and an electrical device. The battery cell (20) comprises a casing (21) and a pressure relief component (214). The casing (21) is provided with a first wall portion (211), and the first wall portion (211) has a first outer surface (2111) facing away from the interior of the casing (21). The pressure relief component (214) is provided on the first wall portion (211), the pressure relief component (214) comprises a first weak portion (2145), and the pressure relief component (214) is configured to crack along at least a portion of the first weak portion (2145) when the battery cell (20) undergoes pressure relief. The minimum radial dimension of the first outer surface (2111) is A, the radial direction refers to a direction passing through the center point of the first outer surface (2111), and the outer edge of the first outer surface (2111) is offset by a predetermined distance L1 towards the center point of the first outer surface (2111) to form a first edge (2143), wherein L1=0.05*A. Along the thickness direction of the first wall portion (211), the projection of the first weak portion (2145) on the first outer surface (2111) is located within the first edge (2143). The first edge (2143) defines a first region (2144) having small rigidity. Under the same initiation pressure, the first weak portion (2145) located in the first region (2144) may have a larger thickness, so that the first weak portion (2143) is not prone to cracking in advance, thereby prolonging the service life of the battery cell (20).

Description

Battery cells, batteries and electrical equipment Technical Field

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

[0002] Batteries are widely used in new energy applications, such as electric vehicles and new energy vehicles. These have become a new trend in the automotive industry. The development of battery technology requires consideration of multiple design factors, including performance parameters such as energy density, discharge capacity, and charge / discharge rate. Furthermore, battery life must be considered. However, current batteries have a relatively short lifespan.

[0003] Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a battery cell, a battery, and an electrical device, which are intended to improve the problem of short battery life in the related art.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, comprising a shell and a pressure relief component, wherein the shell has a first wall portion, the first wall portion having a first outer surface facing away from the interior of the shell; the pressure relief component is arranged on the first wall portion, the pressure relief component includes a first weak portion, and the pressure relief component is configured to be able to crack along at least a portion of the first weak portion when the battery cell is depressurized; wherein the minimum radial dimension of the first outer surface is A, the radial direction refers to the direction passing through the center point of the first outer surface, and the outer edge of the first outer surface is offset toward the center point of the first outer surface by a predetermined distance L1 to form a first edge, wherein L1=0.05*A; along the thickness direction of the first wall portion, the projection of the first weak portion on the first outer surface is located within the first edge.

[0006] In the above technical solution, the outer edge of the first outer surface is offset by 0.05A toward the center point of the first outer surface to form a first edge, and the first edge defines a first area on the first wall portion. The first area is close to the center of the wall portion. The first area is an area on the wall portion with relatively low rigidity and weak ability to resist deformation. When the battery cell releases internal pressure, the first area undergoes a large deformation under the action of gas, and the first weak portion provided in the first area is easily deformed and damaged. Therefore, under the same detonation pressure, the thickness of the first weak portion provided in the first area can be larger. In this way, when the battery cell is in normal use, the first weak portion is not likely to crack prematurely due to pressure changes inside the battery cell or external impact, which is beneficial to reducing the risk of premature damage to the first weak portion and is beneficial to improving the life of the battery cell. Furthermore, the thicker the first weak portion, the easier it is to manufacture, and the lower the precision requirements for the manufacturing equipment.

[0007] As an optional technical solution of an embodiment of the present application, the shell is a cylindrical structure, the shell includes a second wall portion, the second wall portion is arranged around the first wall portion, the first outer surface is a circular structure, and the minimum radial dimension of the first outer surface is the diameter of the circular surface.

[0008] In the above technical solution, the housing is cylindrical, and the second wall portion surrounds the first wall portion. The second wall portion thus constitutes the circumferential wall of the housing, and the first wall portion is connected to one end of the second wall portion. In this case, the first outer surface is a circular structure, the minimum radial dimension of the first outer surface is the diameter of the circular surface, and the first edge is a circle with a diameter of 0.9A.

[0009] As an optional technical solution of an embodiment of the present application, the shell is a prismatic structure, the first outer surface is a rectangular structure, the first outer surface includes two first long sides and two first short sides, the two first long sides are arranged opposite to each other along the width direction of the first wall portion, and the two first short sides are arranged opposite to each other along the length direction of the first wall portion, and the two first long sides and the two first short sides are offset toward the center point of the first outer surface by the predetermined distance L1 to form the first edge.

[0010] In the above technical solution, the first edge is a rectangular structure, the long side of the first edge is formed by the two first long sides of the first outer surface offset toward the center point of the first outer surface, and the short side of the first edge is formed by the two first short sides of the first outer surface offset toward the center point of the first outer surface.

[0011] As an optional technical solution of an embodiment of the present application, the first weak portion includes at least one priority ignition zone, which cracks earlier than other areas of the first weak portion when the battery cell is depressurized. The minimum distance between the projection of the priority ignition zone on the first outer surface along the thickness direction of the first wall portion and the center point of the first outer surface is L2, and the minimum thickness of the priority ignition zone is D, satisfying: 5mm≤L2≤40mm, 0.05mm≤D≤0.6mm.

[0012] In the above technical solution, the first weak portion has a priority ignition zone. When the battery cell is depressurized, the priority ignition zone cracks first, and then the other areas of the first weak portion gradually crack along the extension direction of the first weak portion. When D ≥ 0.05mm, the minimum thickness of the priority ignition zone is larger, so that the priority ignition zone is not easy to crack prematurely due to changes in air pressure inside the battery cell or external impact, which is beneficial to improving the life of the battery cell. When D ≤ 0.6mm, the minimum thickness of the priority ignition zone is not too large, so that the priority ignition zone can be cracked in time when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell. Therefore, when 0.05mm ≤ D ≤ 0.6mm, the priority ignition zone is not easy to crack due to changes in air pressure inside the battery cell or external impact, and it is convenient for the priority ignition zone to crack in time, which is beneficial to improving the timeliness of the pressure relief of the battery cell. When L2 ≥ 5 mm, the minimum distance between the projection of the priority ignition zone along the thickness direction of the first wall onto the first outer surface and the center point of the first outer surface is large, and the rigidity of the location of the priority ignition zone is high. During normal use of the battery cell, the priority ignition zone is less likely to rupture prematurely due to pressure changes within the battery cell or external impact, thereby reducing the risk of premature damage to the priority ignition zone. When L2 ≤ 40 mm, the minimum distance between the projection of the priority ignition zone along the thickness direction of the first wall onto the first outer surface and the center point of the first outer surface is not excessively large. When the battery cell releases internal pressure, the priority ignition zone undergoes significant deformation under the action of gas, allowing the priority ignition zone to rupture promptly, thereby improving the timeliness of pressure release in the battery cell. Therefore, when 5 mm ≤ L2 ≤ 40 mm, the priority ignition zone is not only less likely to rupture due to pressure changes within the battery cell or external impact, but also facilitates the timely rupture of the priority ignition zone, thereby improving the timeliness of pressure release in the battery cell.

[0013] As an optional technical solution of the embodiment of the present application, 0.1mm≤D≤0.5mm.

[0014] In the above technical solution, when D ≥ 0.1mm, the risk of the priority ignition zone cracking due to changes in air pressure inside the battery cell or external impact can be further reduced, which is beneficial to improving the life of the battery cell. When D ≤ 0.5mm, the priority ignition zone can be cracked more promptly when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell. Therefore, when 0.1mm ≤ D ≤ 0.5mm, the priority ignition zone is less likely to crack due to changes in air pressure inside the battery cell or external impact. At the same time, the priority ignition zone can be cracked more promptly when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell.

[0015] As an optional technical solution of the embodiment of the present application, 10mm≤L2≤30mm.

[0016] In the above technical solution, when L2 ≥ 10mm, the rigidity of the location of the priority ignition zone is greater, and the priority ignition zone is less likely to crack prematurely due to pressure changes inside the battery cell or external impact, which is beneficial to reducing the risk of premature damage to the priority ignition zone. When L2 ≤ 30mm, when the battery cell releases internal pressure, the priority ignition zone undergoes a large deformation under the action of gas, so that the priority ignition zone can crack more promptly, which is beneficial to improving the timeliness of pressure relief of the battery cell. Therefore, when 10mm ≤ L2 ≤ 30mm, the priority ignition zone is not easily cracked due to pressure changes inside the battery cell or external impact, and it is convenient for the priority ignition zone to crack in time, which is beneficial to improving the timeliness of pressure relief of the battery cell.

[0017] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, and the first groove includes a first groove section and a second groove section, the first groove section and the second groove section are connected, the center line of the groove bottom surface of the first groove section and the center line of the groove bottom surface of the second groove section intersect at a first intersection, the extension direction of the center line of the groove bottom surface of the first groove section is parallel to the extension direction of the first groove section, and the extension direction of the center line of the groove bottom surface of the second groove section is parallel to the extension direction of the second groove section, and the area of ​​the first weak portion within the range of radius R with the first intersection as the center is the priority detonation zone, A>R=5mm.

[0018] In the above technical solution, the stress at the intersection of the first groove segment and the second groove segment is more concentrated, and the area of ​​the first weak part within the range of 5mm in radius with the first intersection as the center is the priority ignition zone. When the battery cell is depressurized, the priority ignition zone cracks first, and then the first groove segment and the second groove segment gradually crack along their extension direction, thereby realizing rapid pressure relief of the battery cell.

[0019] As an optional technical solution of an embodiment of the present application, the first groove includes a third groove section, the first groove section and the third groove section are arranged opposite to each other, the second groove section connects the first groove section and the third groove section, the center line of the groove bottom surface of the second groove section intersects with the center line of the groove bottom surface of the third groove section at a second intersection, the extension direction of the center line of the groove bottom surface of the third groove section is parallel to the extension direction of the third groove section, and the area of ​​the first weak portion within the range of radius R with the second intersection as the center of the circle is the priority detonation zone.

[0020] In the above technical solution, the stress at the intersection of the second groove segment and the third groove segment is more concentrated, and the area of ​​the first weak part within the range of 5mm in radius with the second intersection as the center is also the priority ignition area. When the battery cell is depressurized, the two priority ignition areas crack first, and then the first groove segment, the second groove segment and the third groove segment gradually crack along their extension direction, thereby realizing rapid pressure relief of the battery cell.

[0021] As an optional technical solution of an embodiment of the present application, the maximum radial dimension of the first outer surface is B, satisfying: B≥A≥10mm.

[0022] In the above technical solution, when A ≥ 10 mm, the minimum radial dimension of the first outer surface is relatively large, and the stiffness of the first wall portion near the outer edge of the first outer surface and the stiffness of the first wall portion near the center point of the first outer surface are quite different. In this case, arranging the first weak portion inside the first edge has a better effect. The maximum radial dimension of the first outer surface can be equal to the minimum radial dimension of the first outer surface. For example, when the first outer surface is a circular structure, the maximum radial dimension of the first outer surface and the minimum radial dimension of the first outer surface are both the diameter of the circular structure. The maximum radial dimension of the first outer surface can be greater than the minimum radial dimension of the first outer surface. For example, when the first outer surface is a rectangular structure, the maximum radial dimension of the first outer surface is the length of the diagonal of the rectangular structure, and the minimum radial dimension of the first outer surface is the width of the rectangular structure.

[0023] As an optional technical solution of the embodiment of the present application, the thickness of the area of ​​the pressure relief component where the first weak portion is not provided is D1, which satisfies: 0.1 mm ≤ D1 ≤ 10 mm.

[0024] In the above technical solution, when D1 ≥ 0.1 mm, the thickness of the area where the first weak portion is not provided on the pressure relief component is larger, and the minimum thickness of the first weak portion provided on the pressure relief component can also be larger. In this way, when the battery cell is in normal use, the first weak portion is not likely to crack prematurely due to pressure changes inside the battery cell or external impact, which is beneficial to reducing the risk of premature damage to the first weak portion and improving the life of the battery cell. When D1 ≤ 10 mm, the thickness of the area where the first weak portion is not provided on the pressure relief component is not too large, and there is no need to remove too much material when processing the first weak portion, which is beneficial to reducing material waste and reducing processing difficulty. Therefore, when 0.1 mm ≤ D1 ≤ 10 mm, the thickness of the processed first weak portion can be made more appropriate, reducing the risk of premature damage to the first weak portion and improving the life of the battery cell. In addition, it is beneficial to reduce material waste and reduce processing difficulty.

[0025] As an optional technical solution of an embodiment of the present application, the housing includes a second wall portion adjacent to the first wall portion, and the second wall portion is directly connected to the first wall portion.

[0026] In the above technical solution, the second wall portion is directly connected to the first wall portion, and there is no need to use a rounded corner transition between the second wall portion and the first wall portion, which is simpler and more convenient during manufacturing.

[0027] As an optional technical solution of an embodiment of the present application, the outer shell includes a shell and an end cover, and an opening is formed at least at one end of the shell; the end cover corresponds to the opening one by one, and the end cover closes the opening; wherein, at least one wall in the shell is the first wall portion.

[0028] In the above technical solution, when the shell includes a first wall portion, the pressure relief component is arranged on a wall of the shell. The fluid medium sprayed by the pressure relief component is not easy to act on other electrical connection structures on the end cover, which is beneficial to reduce the risk of short circuit of the battery cell.

[0029] As an optional technical solution of the embodiment of the present application, the thickness of the area of ​​the pressure relief component where the first weak portion is not provided is smaller than the thickness of the end cover.

[0030] In the above technical solution, by making the thickness of the region of the pressure relief component where the first weak portion is not provided smaller than the thickness of the end cover, it is easier to release pressure from the pressure relief component when the battery cell releases pressure.

[0031] As an optional technical solution of the embodiment of the present application, the material of the pressure relief component includes aluminum or steel.

[0032] In the above technical solution, aluminum or steel is used as the material of the pressure relief component, so that the first weak portion has higher strength. When the battery cell is in normal use, the first weak portion is not easily cracked prematurely due to pressure changes inside the battery cell or external impact, which is beneficial to reducing the risk of the first weak portion being damaged prematurely and is beneficial to improving the life of the battery cell.

[0033] As an optional technical solution of the embodiment of the present application, the pressure relief component is integrally formed with the first wall portion.

[0034] In the above technical solution, the pressure relief component is integrally formed with the first wall portion, eliminating the need for additional welding or bonding processes, thereby reducing the risk of leakage from the pressure relief component. Furthermore, during production, the detonation pressures of multiple battery cells can be made more consistent.

[0035] As an optional technical solution of an embodiment of the present application, the pressure relief component is separately provided from the first wall portion, the first wall portion is provided with a pressure relief hole, and the pressure relief component is installed on the first wall portion and covers the pressure relief hole.

[0036] In the above technical solution, the pressure relief component is separately provided from the first wall portion and installed on the first wall portion, so as to facilitate processing and manufacturing.

[0037] In a second aspect, an embodiment of the present application further provides a battery, which includes the above-mentioned battery cell.

[0038] In a third aspect, an embodiment of the present application further provides an electrical device, which includes the above-mentioned battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0040] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0041] FIG2 is an exploded view of the structure of a battery provided in some embodiments of the present application;

[0042] FIG3 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0043] FIG4 is an exploded view of the structure of a battery cell provided in some embodiments of the present application;

[0044] FIG5 is a bottom view of a housing of a battery cell provided in some embodiments of the present application;

[0045] FIG6 is a partial cross-sectional view of a housing of a battery cell provided in some embodiments of the present application;

[0046] FIG7 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application;

[0047] FIG8 is a top view of a housing of a battery cell provided in some other embodiments of the present application;

[0048] FIG9 is a bottom view of the outer shell of a battery cell provided in some other embodiments of the present application.

[0049] Icon: 1000-vehicle; 100-battery; 10-box; 11-first box body; 12-second box body; 20-battery cell; 21-housing; 211-first wall; 2111-first outer surface; 21111-first long side; 21112-first short side; 2112-first inner surface; 212-second wall; 2121-second outer surface; 2131-arc transition surface; 214-pressure relief component; 2141-first groove; 214 1a-first slot section; 2141b-second slot section; 2141c-third slot section; 2142-priority ignition zone; 21421-first intersection; 21422-second intersection; 2143-first edge; 2144-first area; 2145-first weak part; 215-shell; 2151-opening; 216-end cover; 22-electrode assembly; 221-electrode ear; 23-electrode terminal; 24-current collecting component; 200-controller; 300-motor. DETAILED DESCRIPTION

[0050] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0051] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0052] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0053] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0054] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0055] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0056] The term "plurality" used in this application refers to two or more (including two).

[0057] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0058] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0059] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0060] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0061] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0062] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0063] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and at least one of its modified compounds, etc.

[0064] In some embodiments, a positive electrode may utilize a metal foam. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or the like. When a metal foam is used as the positive electrode, the surface of the metal foam may or may not include a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled or / and deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0065] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0066] As an example, the negative electrode current collector may be a metal foil, a metal foam, or a composite current collector. For example, as the metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. may be used. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, etc. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0067] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0068] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either or both of the two facing surfaces of the negative electrode current collector.

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

[0070] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0071] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0072] In some embodiments, the separator is a separator membrane. There are many types of separator membranes, and any known separator membrane with a porous structure having good chemical stability and mechanical stability can be selected.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0093] As an example, the battery cells may be cylindrical, prismatic, soft-pack or other shaped battery cells. Prismatic battery cells include but are not limited to square-shell, blade-shaped, and polygonal batteries, such as hexagonal batteries.

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

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

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

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

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

[0099] Batteries are widely used in new energy applications, such as electric vehicles and new energy vehicles. These have become a new trend in the automotive industry. The development of battery technology requires consideration of multiple design factors, including performance parameters such as energy density, discharge capacity, and charge / discharge rate. Furthermore, battery life must be considered. However, current batteries have a relatively short lifespan.

[0100] For battery cells, in order to improve the reliability of battery cells, the existing technology is to weld a pressure relief mechanism on the battery cells. A weak portion is provided on the pressure relief mechanism, and the weak portion defines a pressure relief portion. When the internal pressure of the battery cell reaches the detonation pressure, the weak portion cracks and the pressure relief portion opens to release the pressure inside the battery cell, thereby reducing the risk of battery cell explosion or fire.

[0101] However, the weak part often cracks prematurely, that is, before the internal pressure of the battery cell reaches the desired detonation pressure, the weak part has already cracked, causing the battery cell to be scrapped prematurely and the battery cell life to be shortened.

[0102] In view of this, an embodiment of the present application provides a battery cell, which includes a shell and a pressure relief component, wherein the shell has a first wall portion, the first wall portion has a first outer surface facing away from the interior of the shell, and the pressure relief component is arranged on the first wall portion. The pressure relief component includes a first weak portion, and the pressure relief component is configured to be able to break along at least a portion of the first weak portion when the battery cell is depressurized. The minimum radial dimension of the first outer surface is A, and the radial direction refers to the direction passing through the center point of the first outer surface. The outer edge of the first outer surface is offset toward the center point of the first outer surface by a predetermined distance L1 to form a first edge, wherein L1 = 0.05*A. Along the thickness direction of the first wall portion, the projection of the first weak portion on the first outer surface is located within the first edge.

[0103] The outer edge of the first outer surface is offset by 0.05A toward the center point of the first outer surface to form a first edge, and the first edge defines a first area on the first wall portion. The first area is close to the center of the wall portion. The first area is an area on the wall portion with relatively low rigidity and weak ability to resist deformation. When the battery cell releases internal pressure, the first area undergoes a large deformation under the action of the gas, and the first weak portion provided in the first area is easily deformed and damaged. Therefore, under the same detonation pressure, the thickness of the first weak portion provided in the first area can be larger. In this way, when the battery cell is in normal use, the first weak portion is not likely to crack prematurely due to pressure changes inside the battery cell or external impact, which is beneficial to reducing the risk of premature damage to the first weak portion and is beneficial to increasing the life of the battery cell. Furthermore, the thicker the first weak portion, the easier it is to manufacture, and the lower the precision requirements for the manufacturing equipment.

[0104] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and batteries disclosed in this application can be used to construct the electrical device, thereby increasing the life of the battery cells.

[0105] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0106] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device according to an embodiment of the present application.

[0107] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments 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 provided inside the vehicle 1000. The battery 100 can be arranged at the bottom of the vehicle 1000, or at the head of the vehicle 1000, or at the tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can be used as an operating power source or a power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0108] In some embodiments of the present application, the battery 100 can not only serve as the operating power source or usage power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0109] 2 and 3 , FIG2 is an exploded view of a battery 100 according to some embodiments of the present invention, and FIG3 is a schematic diagram of a battery cell 20 according to some embodiments of the present invention. The battery 100 includes a housing 10 and a battery cell 20 , wherein the battery cell 20 is accommodated in the housing 10 .

[0110] The housing 10 is used to provide assembly space for the battery cells 20 and can adopt a variety of structures. In some embodiments, the housing 10 can include a first housing body 11 and a second housing body 12. The first housing body 11 and the second housing body 12 cover each other, and the first housing body 11 and the second housing body 12 jointly define an assembly space for accommodating the battery cells 20. The second housing body 12 can be a hollow structure with one end open, and the first housing body 11 can be a plate-like structure. The first housing body 11 covers the open side of the second housing body 12, so that the first housing body 11 and the second housing body 12 jointly define the assembly space. The first housing body 11 and the second housing body 12 can also be hollow structures with one end open, and the open side of the first housing body 11 covers the open side of the second housing body 12.

[0111] Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder, a cuboid or a cube, etc. For example, in FIG2 , the box body 10 is in the shape of a cuboid.

[0112] In the battery 100, there can be one or more battery cells 20 disposed within the housing 10. When there are multiple battery cells 20 disposed within the housing 10, the multiple battery cells 20 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel configurations within the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery 100 can be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid configuration to form a battery module, which is then further connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed within the housing 10.

[0113] In some embodiments, the battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, which is used to connect the multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20 .

[0114] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be a rectangular parallelepiped, a cylinder, a prism, or other shapes. For example, in FIG3 , the battery cell 20 is a rectangular parallelepiped.

[0115] According to some embodiments of the present application, please refer to Figures 3, 4, 5, 6, 7, and 8. Figure 4 is an exploded view of the structure of a battery cell 20 provided in some embodiments of the present application. Figure 5 is a bottom view of the outer shell 21 of the battery cell 20 provided in some embodiments of the present application. Figure 6 is a partial cross-sectional view of the outer shell 21 of the battery cell 20 provided in some embodiments of the present application. Figure 7 is a schematic diagram of the structure of the battery cell 20 provided in other embodiments of the present application. Figure 8 is a top view of the outer shell 21 of the battery cell 20 provided in other embodiments of the present application. The present application provides a battery cell 20, comprising an outer shell 21 and a pressure relief component 214. The outer shell 21 has a first wall 211, and the first wall 211 has a first outer surface 2111 facing away from the interior of the outer shell 21. The pressure relief component 214 is disposed on the first wall 211 and includes a first weakened portion 2145. The pressure relief component 214 is configured to rupture along at least a portion of the first weakened portion 2145 when the battery cell 20 releases pressure. The minimum radial dimension of the first outer surface 2111 is A, where the radial direction refers to the direction passing through the center point of the first outer surface 2111. The outer edge of the first outer surface 2111 is offset from the center point of the first outer surface 2111 by a predetermined distance L1 to form a first edge 2143, where L1 = 0.05 * A. Along the thickness direction of the first wall portion 211, the projection of the first weak portion 2145 onto the first outer surface 2111 is located within the first edge 2143.

[0116] The battery cell 20 refers to the smallest unit constituting the battery 100 .

[0117] The housing 21 includes an end cover 216 and a shell 215 . The shell 215 has an opening 2151 . The end cover 216 is connected to the shell 215 and closes the opening 2151 .

[0118] The end cap 216 refers to a component that covers the opening 2151 of the shell 215 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 216 can be adapted to the shape of the shell 215 to match the shell 215. Optionally, the end cap 216 can be made of a material with a certain hardness and strength (such as an aluminum alloy), so that the end cap 216 is not easily deformed when squeezed or collided, so that the battery cell 20 can have a higher structural strength and improved safety performance. The material of the end cap 216 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application are not particularly limited to this. In some embodiments, the battery cell 20 also includes an insulating member, which is arranged on the inner side of the end cap 216. The insulating member can be used to isolate the electrical connection components in the shell 215 from the end cap 216 to reduce the risk of short circuit. Exemplary, the insulating member can be plastic, rubber, etc.

[0119] The housing 215 is a component used to cooperate with the end cap 216 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 22, electrolyte, and other components. The housing 215 and the end cap 216 can be independent components. An opening 2151 can be provided on the housing 215, and the end cap 216 is closed at the opening 2151 to form the internal environment of the battery cell 20. Without limitation, the end cap 216 and the housing 215 can also be integrated. Specifically, the end cap 216 and the housing 215 can form a common joint surface before other components are inserted into the housing. When the interior of the housing 215 needs to be encapsulated, the end cap 216 is closed to the housing 215. The housing 215 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 215 can be determined according to the specific shape and size of the electrode assembly 22. The shell 215 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0120] The electrode assembly 22 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 22 may be contained in the housing 21. The electrode assembly 22 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active materials constitute the main body of the electrode assembly 22, and the parts of the positive electrode sheet and the negative electrode sheet without active materials each constitute a tab 221. The positive electrode tab and the negative electrode tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery 100, the positive electrode active material and the negative electrode active material react with the electrolyte.

[0121] In some embodiments, as shown in FIG. 4 , the battery cell 20 may further include an electrode terminal 23 . The electrode terminal 23 is insulated and mounted on the housing 21 . The electrode terminal 23 is electrically connected to the electrode assembly 22 to output or input electrical energy of the battery cell 20 .

[0122] It should be noted that the electrode terminal 23 is insulated and mounted on the housing 21 , that is, there is no electrical connection between the electrode terminal 23 and the housing 21 .

[0123] 3 and 4 , the battery cell 20 includes two electrode terminals 23 , which are spaced apart on the end cover 216 . Correspondingly, each electrode assembly 22 has two pole tabs 221 , and the polarities of the two pole tabs 221 are opposite. The two electrode terminals 23 are electrically connected to the two pole tabs 221 of the electrode assembly 22 , respectively, to realize the input or output of the positive and negative poles of the battery cell 20 .

[0124] Exemplarily, the electrode terminal 23 may be made of a variety of materials. For example, the electrode terminal 23 may be made of copper, iron, aluminum, steel, or aluminum alloy.

[0125] Optionally, the electrode terminals 23 may be mounted on the housing 21 in various configurations. For example, in Figures 3 and 4 , both electrode terminals 23 are mounted on the end cap 216 of the housing 21. Of course, the structure of the battery cell 20 is not limited thereto. In other embodiments, both electrode terminals 23 may be mounted on the shell 215 of the housing 21. Similarly, one electrode terminal 23 may be mounted on the shell 215 of the housing 21, while the other electrode terminal 23 may be mounted on the end cap 216 of the housing 21.

[0126] In some embodiments, as shown in Figure 4, the battery cell 20 may also include two current collecting components 24, both of which are arranged in the outer shell 21, and each current collecting component 24 is used to connect an electrode terminal 23 and a plurality of electrode assemblies 22 with the same polarity of the electrode lugs 221 to achieve electrical connection between the electrode terminal 23 and the electrode assembly 22, which is conducive to reducing the difficulty of assembly between the electrode lug 221 and the electrode terminal 23.

[0127] For example, the current collecting member 24 may be made of a variety of materials. For example, the current collecting member 24 may be made of copper, iron, aluminum, steel, or aluminum alloy.

[0128] The first wall portion 211 may be the end cap 216 of the housing 21, or may be a wall of the shell 215 of the housing 21. For example, in Figures 3 and 4, the first wall portion 211 is the bottom wall of the shell 215 that is disposed opposite the end cap 216. In other embodiments, the first wall portion 211 may also be a side wall of the shell 215 that is adjacent to and connected to the end cap 216.

[0129] The first outer surface 2111 is the surface of the first wall portion 211 facing away from the interior of the housing 21. The first outer surface 2111 is a plane. For example, when the first wall portion 211 is a rectangular parallelepiped structure, the first outer surface 2111 is the rectangular surface of the first wall portion 211 facing away from the interior of the housing 21. For another example, when the first wall portion 211 is a disc structure, the first outer surface 2111 is the circular surface of the first wall portion 211 facing away from the interior of the housing 21.

[0130] In some embodiments, the housing 21 includes a second wall portion 212 adjacent to the first wall portion 211. The second wall portion 212 has a second outer surface 2121 facing away from the interior of the housing 21. The first outer surface 2111 can be directly connected to the second outer surface 2121. In this case, an edge is formed at the location where the first outer surface 2111 and the second outer surface 2121 connect. The first outer surface 2111 can also be connected to the second outer surface 2121 via a circular arc transition surface 2131. In this case, the first outer surface 2111 and the second outer surface 2121 have a rounded transition.

[0131] The pressure relief component 214 can be a component mounted on the first wall portion 211. In this case, the pressure relief component 214 is separately mounted and connected to the first wall portion 211. For example, the pressure relief component 214 is a bursting disk mounted on the first wall portion 211. The pressure relief component 214 can also be a portion of the first wall portion 211. In this case, the pressure relief component 214 and the first wall portion 211 are integrally formed. The location of the pressure relief component 214 can be used to determine which wall of the housing 21 is the first wall portion 211. For example, when the pressure relief component 214 is mounted on the end cap 216, the end cap 216 is the first wall portion 211. When the pressure relief component 214 is mounted on the bottom wall of the housing 215, the bottom wall is the first wall portion 211. When the pressure relief component 214 is mounted on a side wall of the housing 215, the side wall is the first wall portion 211.

[0132] The first weak portion 2145 serves as a pressure relief mechanism. When the internal pressure or temperature of the battery cell 20 reaches a predetermined value, the pressure relief component 214 can rupture along the first weak portion 2145 to release the pressure within the battery cell 20. In some embodiments, the strength of the pressure relief component 214 at the first weak portion 2145 can be lower than that at other locations. This allows the first weak portion 2145 to rupture under the internal pressure to release the pressure within the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches the predetermined value. In other embodiments, the melting point of the pressure relief component 214 at the first weak portion 2145 can be lower than that at other locations. This allows the first weak portion 2145 to rupture under the influence of high temperature to release the pressure within the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches the predetermined value. Referring to FIG. 6 , a cross-section of the first weak portion 2145 is shown with a cross-hatched fill pattern to facilitate visualization of the location of the first weak portion 2145.

[0133] A represents the minimum radial dimension of the first outer surface 2111. The "minimum radial dimension of the first outer surface 2111" refers to the dimension of the shortest straight line segment among a plurality of straight line segments that have any two points on the outer edge of the first outer surface 2111 as endpoints and pass through the center point of the first outer surface 2111. Please refer to Figures 5 and 6. In the embodiments shown in Figures 5 and 6, the first outer surface 2111 is a rectangular structure, and the minimum radial dimension of the first outer surface 2111 is the width of the rectangle. Please refer to Figures 7 and 8. In the embodiments shown in Figures 7 and 8, the first outer surface 2111 is a circular structure, and the minimum radial dimension of the first outer surface 2111 is the diameter of the circular surface. For example, in some embodiments, the first outer surface 2111 is a regular hexagon, and the minimum radial dimension of the first outer surface 2111 is the distance between two parallel sides of the regular hexagon.

[0134] The first edge 2143 is formed by offsetting the outer edge of the first outer surface 2111 by a predetermined distance L1 from the center of the first outer surface 2111. For example, if the first outer surface 2111 is a rectangle, the first edge 2143 is formed by translating the two long sides and the two short sides of the first outer surface 2111 toward the intersection of the rectangle's diagonals by a predetermined distance L1. For example, if the first outer surface 2111 is a circle, the first edge 2143 is formed by translating the circumference of the first outer surface 2111 toward the center of the circle by a predetermined distance L1.

[0135] Wherein, L1=0.05*A, that is, the predetermined distance L1 is 0.05 times the minimum radial dimension of the first outer surface 2111 .

[0136] 5 and 6 , the thickness direction of the first wall portion 211 is the X direction shown in the figures.

[0137] “Along the thickness direction of the first wall portion 211 , the projection of the first weak portion 2145 on the first outer surface 2111 is located within the first edge 2143 ” can also be understood as: the area of ​​the first wall portion 211 within the first edge 2143 is the first area 2144 , and the first weak portion 2145 is arranged in the first area 2144 .

[0138] The outer edge of the first outer surface 2111 is offset by 0.05Å toward the center of the first outer surface 2111 to form a first edge 2143. This first edge 2143 defines a first region 2144 on the first wall portion 211. The first region 2144 is located near the center of the wall portion. This region has relatively low rigidity and is less resistant to deformation. When the battery cell 20 releases internal pressure, the first region 2144 undergoes significant deformation under the action of the gas, making the first weak portion 2145 located in the first region 2144 susceptible to deformation and failure. Therefore, under the same detonation pressure, the thickness of the first weak portion 2145 located in the first region 2144 can be increased. This reduces the risk of premature rupture of the first weak portion 2145 due to internal pressure fluctuations or external impact during normal use of the battery cell 20, thereby reducing the risk of premature failure of the first weak portion 2145 and improving the lifespan of the battery cell 20. Furthermore, the greater the thickness of the first weak portion 2145 , the easier it is to manufacture, and the lower the precision requirement for manufacturing equipment.

[0139] 7 and 8 , in some embodiments, the housing 21 is cylindrical and includes a second wall portion 212 disposed around the first wall portion 211. The first outer surface 2111 is circular, and the minimum radial dimension of the first outer surface 2111 is the diameter of the circular surface.

[0140] The housing 21 has a cylindrical structure, and the second wall portion 212 is disposed around the first wall portion 211. The second wall portion 212 thus serves as the peripheral wall of the housing 215, and the first wall portion 211 is connected to one end of the second wall portion 212. The first wall portion 211 may be an end cap 216 or a bottom wall of the housing 215. The bottom wall and the end cap 216 are disposed at opposite ends of the second wall portion 212.

[0141] The first outer surface 2111 is a circular structure. The minimum radial dimension of the first outer surface 2111 is the diameter of the circular surface. The first edge 2143 is a circle with a diameter of 0.9A.

[0142] Referring again to Figures 5 and 6, in some embodiments, the housing 21 has a prismatic structure, and the first outer surface 2111 has a rectangular structure. The first outer surface 2111 includes two first long sides 21111 and two first short sides 21112. The two first long sides 21111 are disposed opposite each other along the width direction of the first wall portion 211, and the two first short sides 21112 are disposed opposite each other along the length direction of the first wall portion 2111. The two first long sides 21111 and the two first short sides 21112 are offset from the center point of the first outer surface 2111 by a predetermined distance L1 to form a first edge 2143.

[0143] The housing 21 is a prism structure. Please refer to FIG. 5 and FIG. 6 . In the embodiments shown in FIG. 5 and FIG. 6 , the housing 21 is a quadrangular prism structure, that is, a rectangular parallelepiped structure.

[0144] The first outer surface 2111 is a rectangular structure and includes two first long sides 21111 and two first short sides 21112. The first long sides 21111 and the first short sides 21112 can be directly connected, in which case the first long sides 21111 and the first short sides 21112 form an angled corner. The first long sides 21111 and the first short sides 21112 can also be transitioned through an arc segment.

[0145] When the first long side 21111 and the first short side 21112 are directly connected, the two first long sides 21111 and the two first short sides 21112 are offset from the center point of the first outer surface 2111 by a predetermined distance L1 to form a first edge 2143 .

[0146] When the first long side 21111 and the first short side 21112 transition through an arc segment and the predetermined distance L1 is greater than or equal to the radius of the arc segment, the two first long sides 21111 and the two first short sides 21112 are offset by a predetermined distance L1 toward the center point of the first outer surface 2111 to form a first edge 2143 (because the predetermined offset distance is greater than or equal to the radius of the arc segment, an arc segment is no longer required after the offset to form a closed first edge 2143).

[0147] When the first long side 21111 and the first short side 21112 transition through an arc segment and the predetermined distance L1 is less than the radius of the arc segment, the two first long sides 21111 and the two first short sides 21112 are offset by a predetermined distance L1 toward the center point of the first outer surface 2111. At the same time, the arc segment also needs to be offset by a predetermined distance L1 toward its corresponding center point to connect the offset first long side 21111 and the first short side 21112 to form a first edge 2143.

[0148] The first edge 2143 is a rectangular structure, and the long side of the first edge 2143 is formed by the two first long sides 21111 of the first outer surface 2111 offset toward the center point of the first outer surface 2111, and the short side of the first edge 2143 is formed by the two first short sides 21112 of the first outer surface 2111 offset toward the center point of the first outer surface 2111.

[0149] Referring to Figures 5 and 6 , in some embodiments, the first weak portion 2145 includes at least one preferential initiation region 2142. This preferential initiation region 2142 ruptures before other regions of the first weak portion 2145 when the battery cell 20 is depressurized. The minimum distance between the projection of the preferential initiation region 2142 along the thickness direction of the first wall portion 211 on the first outer surface 2111 and the center point of the first outer surface 2111 is L2. The minimum thickness of the preferential initiation region 2142 is D, satisfying the following conditions: 5 mm ≤ L2 ≤ 40 mm, and 0.05 mm ≤ D ≤ 0.6 mm.

[0150] The preferential initiation area 2142 is a region of the first weak portion 2145 that preferentially initiates when the battery cell 20 is depressurized. The preferential initiation area 2142 cracks more significantly than other regions of the first weak portion 2145 when the battery cell 20 is depressurized.

[0151] L2 represents the minimum distance between the projection of the priority initiation zone 2142 along the thickness direction of the first wall portion 211 onto the first outer surface 2111 and the center point of the first outer surface 2111. The location of the priority initiation zone 2142 can be determined through thermal runaway testing by measuring the horizontal distance between the priority initiation zone 2142 and the center point of the first outer surface 2111.

[0152] The minimum distance between the projection of the priority detonation zone 2142 along the thickness direction of the first wall portion 211 on the first outer surface 2111 and the center point of the first outer surface 2111 can be: L2 = 5mm, 8mm, 10mm, 12mm, 15mm, 18mm, 20mm, 25mm, 30mm, 35mm, 40mm, etc.

[0153] D represents the minimum thickness of the priority initiation zone 2142. The location of the priority initiation zone 2142 can be determined through thermal runaway testing, and the minimum thickness of the priority initiation zone 2142 can be measured. Alternatively, the minimum thickness of the priority initiation zone 2142 can be measured through tomography. It should be noted that the minimum thickness of the priority initiation zone 2142 can be greater than the minimum thickness of other areas of the first weak portion 2145, can be equal to the minimum thickness of other areas of the first weak portion 2145, or can be less than the minimum thickness of other areas of the first weak portion 2145. In the embodiments shown in Figures 5 and 6, the minimum thickness of the priority initiation zone 2142 is equal to the minimum thickness of other areas of the first weak portion 2145.

[0154] The minimum thickness of the priority detonation area 2142 can be: D = 0.05 mm, 0.08 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, etc.

[0155] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to Comparative Examples 1 to 2 and Examples 1 to 7. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0156] Example 1

[0157] The battery cells 20 in each embodiment and comparative example were prepared and tested according to the following methods.

[0158] 1. Preparation of Battery Cell 20

[0159] 1) Preparation of positive electrode

[0160] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1 O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are prepared into positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the solid content of LiNi 0.7 Co 0.1 Mn 0.1The mass ratio of O2, Super P and PVDF is 8:1:1. The positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil and dried at 85°C and then cold pressed. Then, it is trimmed, cut and striped, and dried under vacuum conditions at 85°C for 4 hours to make the positive electrode sheet.

[0161] 2) Preparation of negative electrode sheet

[0162] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene-butadiene rubber (SBR) were mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry was 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC, and adhesive styrene-butadiene rubber (SBR) in the solid components was 88:7:3:2. The negative electrode slurry was coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C. Then, it was cold pressed, trimmed, cut into pieces, and slit, and then dried under vacuum conditions at 120°C for 12 hours to prepare a negative electrode sheet.

[0163] 3) Preparation of electrolyte

[0164] In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), the fully dried electrolyte salt LiPF6 was dissolved in a mixed solvent (the mixed solvent included ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 50:50), and after mixing evenly, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0165] 4) Isolation parts

[0166] A 16 μm polyethylene film was used as a separator.

[0167] 5) Preparation of battery cell 20

[0168] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed in the middle of the positive and negative electrode sheets to isolate the positive and negative electrodes. The electrode assembly 22 is wound and placed in an aluminum shell 21. The electrolyte prepared above is injected into the dried shell 21. The battery cell 20 is prepared by packaging, standing, forming, shaping, and capacity testing. A first weak portion 2145 is formed on the first wall 211 of the shell 21 of the battery cell 20. The shell 21 of the battery cell 20 of Example 1 is a rectangular parallelepiped structure, and the shell 215 of the shell 21 is a structure with an opening 2151 formed at one end. The wall opposite to the end cover 216 of the shell 215 is the first wall 211. The first wall 211 is a rectangular wall. A first groove 2141 is provided on the first wall 211. The first weak portion 2145 is formed on the first wall 211 in the area where the first groove 2141 is provided. Among them, the first groove 2141 is an "H"-shaped structure, that is, the first groove 2141 includes a first groove section 2141a, a second groove section 2141b and a third groove section 2141c. The first groove section 2141a and the third groove section 2141c are arranged opposite to each other and both extend along the width direction of the first wall portion 211. The second groove section 2141b is connected between the first groove section 2141a and the third groove section 2141c, and the second groove section 2141b is located in the middle of the first wall portion 211 in the width direction of the first wall portion 211. The center line of the groove bottom surface of the first groove section 2141a and the center line of the groove bottom surface of the second groove section 2141b intersect at a first intersection 21421. The extension direction of the center line of the groove bottom surface of the first groove section 2141a is parallel to the extension direction of the first groove section 2141a, and the extension direction of the center line of the groove bottom surface of the second groove section 2141b is parallel to the extension direction of the second groove section 2141b. The area of ​​first weak portion 2145 within a radius R centered at first intersection 21421 is a priority detonation zone 2142, where A > R = 5 mm. Battery cell 20 has a thickness of 39 mm, a width of 203 mm, a shoulder height (the height dimension of housing 21) of 122.7 mm, and a capacity of 185 Ah.

[0169] The minimum distance L2 between the projection of the priority detonation zone 2142 along the thickness direction of the first wall portion 211 on the first outer surface 2111 and the center point of the first outer surface 2111 and the minimum thickness D of the priority detonation zone 2142 are both obtained through tomography and then measured by software.

[0170] The preparation methods of the battery cells 20 of Comparative Examples 1 to 2 and Examples 2-7 are the same as that of Example 1, except that the minimum distance L2 between the projection of the priority initiation zone 2142 along the thickness direction of the first wall portion 211 on the first outer surface 2111 and the center point of the first outer surface 2111 and the minimum thickness D of the priority initiation zone 2142 are different, as shown in Table 1.

[0171] 2. Performance parameter testing

[0172] 1. Method for measuring the number of cycle fatigue of battery cell 20

[0173] 1) Prepare a special test fixture. Specifically, the fixture includes three 10mm steel plates (first steel plate, second steel plate, and third steel plate). Each steel plate can completely cover the large surface of the battery cell 20. The first steel plate and the third steel plate are located at both ends of the fixture and are fixed by bolts. The second steel plate is located between the first and third steel plates, and the second steel plate is constrained by a guide rail. The second steel plate can only move horizontally along the thickness direction of the second steel plate.

[0174] 2) Install the battery cell 20 between the first steel plate and the second steel plate, and place a support structure between the two large surfaces of the battery cell 20 and the first and second steel plates. The support structure can be an insulation pad or a water-cooling plate (consistent with the material / structure between two adjacent battery cells 20 in the actual battery 100). The support structure can be compressed to provide expansion space for the battery cell 20 during the charge and discharge cycle aging process; the two large surfaces of the battery cell 20 are in contact with the support structure, the first steel plate is in contact with the corresponding support structure, the second steel plate is in contact with the corresponding support structure, and a pressure sensor is provided between the second steel plate and the third steel plate.

[0175] 3) Adjust the position of the second steel plate by adjusting the pre-tightening force of the bolts, observe the pressure sensor, make the initial extrusion force on the battery cell 20 2000N, and connect the positive electrode terminal and the negative electrode terminal of the battery cell 20 to the charging and discharging equipment.

[0176] 4) Place the battery cell 20 and the fixture in a constant temperature environment of 25±2°C, and start the test after the battery cell 20 reaches temperature equilibrium.

[0177] 5) The test steps are carried out in accordance with Section 6.4 "Standard Cycle Life" of "GBT31484-2015 Requirements and Test Methods for 100 Cycle Life of Power Batteries for Electric Vehicles", and the test cycle end condition is changed to "stop testing until damage occurs at the first weak portion 2145 provided on the first wall portion 211".

[0178] Specifically, test according to the following steps:

[0179] a) Discharge to 2.8V with a current of 1I1(A);

[0180] b) Shelved for no less than 30 minutes or under the shelving conditions specified by the enterprise;

[0181] c) Charge in accordance with the method 6.1.1.3 of GBT31484-2015 Requirements and Test Methods for 100 Cycle Life of Power Batteries for Electric Vehicles;

[0182] d) Shelving for no less than 30 minutes or under the shelving conditions specified by the enterprise;

[0183] e) Discharge to 2.8V at a current of 1I1(A);

[0184] f) Repeat steps b) to e) until the first wall portion 211 where the first groove 2141 is provided is damaged and the test is stopped.

[0185] That is, during the test, the area where the first groove 2141 is provided on the first wall portion 211 of the battery cell 20 is continuously observed until the area breaks and leaks. The number of cycles is recorded as the cycle fatigue number of the battery cell 20. The greater the number of cycle fatigue numbers of the battery cell 20, the lower the probability of the battery cell 20 opening the valve and leaking liquid due to gas production during long-term use, and the longer the service life.

[0186] 2. Battery Cell 20 Thermal Runaway Test Method

[0187] 1. Select the heating plate according to the size of the battery cell 20. The size of the heating plate should cover the two large surfaces of the battery cell 20 as much as possible (coverage area ≥ 60%);

[0188] 2. Charge the battery cell 20 to 100% SOC before testing and ensure that the temperature of the battery cell 20 is 25±5℃;

[0189] 3. Sensor layout:

[0190] 1) Temperature sensing wire layout: A layer of Teflon is applied to the center area of ​​each of the two large surfaces of the battery cell 20, a temperature sensing wire is arranged above the Teflon, and another layer of Teflon is applied;

[0191] 2) Layout of voltage sampling lines: A layer of Teflon is applied to the positive electrode terminal, negative electrode terminal and housing 21 of the battery cell 20, and a voltage sampling line is arranged above the Teflon, followed by another layer of Teflon.

[0192] 3) Air pipe arrangement: Drill a hole in the first wall portion 211 of the battery cell 20. The hole is located at the midpoint between the first groove 2141 and the side surface of the housing 215 (the outer surface of the wall portion of the housing 215 adjacent to the first wall portion 211 along the length of the first wall portion 211). Insert the air pipe into the hole and seal it. Connect the air pipe to the air pressure sensor.

[0193] 4) Connect the temperature sensing wire, voltage sampling wire and air pressure sensor to the data acquisition instrument to collect and analyze data in real time. The acquisition frequency of the data acquisition instrument is ≤0.1S;

[0194] 4. Assemble the fixture: completely cover the two large surfaces of the battery cell 20 with the fixture, with a clamping force of 3000N. The arrangement order of the fixture, heating plate and battery cell 20 is: fixture + heating plate + battery cell 20 + fixture;

[0195] 5. Test: Turn on multiple channels to collect temperature, voltage, and air pressure data, then turn on the heating plate at 500W power to heat the battery cell 20 until the battery cell 20 thermally runs away.

[0196] 6. Obtaining the pressure holding time of the battery cell 20: Determine the thermal runaway moment and valve opening moment based on the temperature, voltage, and air pressure data collected from multiple channels, and derive the pressure holding time of the battery cell 20 according to the formula: pressure holding time = valve opening moment - thermal runaway moment.

[0197] Thermal runaway criteria: a) The triggering object generates a voltage drop exceeding 25% of the initial voltage; b) The temperature at the detection point reaches the manufacturer's maximum operating temperature; c) The temperature rise rate dT / dt at the detection point is ≥ 1°C / s and persists for more than 3 seconds. Thermal runaway is determined to have occurred when a) and c) or b) and c) occur, and the moment of thermal runaway is determined.

[0198] Determination of valve opening time: When the air pressure drops by more than 25%, it can be determined that the valve is open (the first wall portion 211 is cracked along the first groove 2141). The moment when the air pressure begins to drop is the valve opening time.

[0199] 3. Test Results

[0200] The experimental results of Comparative Examples 1-2 and Examples 1-7 are shown in Table 1 below:

[0201] Table 1

[0202] Please refer to Table 1. As shown in Comparative Example 1, when L2 is less than 5 mm and D is less than 0.05 mm, the number of cycle fatigue times of the battery cell 20 is small. The priority initiation area 2142 is easily affected by the pressure change inside the battery cell 20, causing the pressure relief component 214 to crack prematurely along the priority initiation area 2142, and the life of the battery cell 20 is shortened.

[0203] Please refer to Table 1. As shown in Comparative Example 2, when L2>40 mm and D>0.6 mm, the battery cell 20 has a longer holding time during thermal runaway, and the battery cell 20 has a poor timeliness in pressure relief during thermal runaway.

[0204] Referring to Table 1, as shown in Examples 1 to 7, when 5 mm ≤ L2 ≤ 40 mm and 0.05 mm ≤ D ≤ 0.6 mm, the holding time of the battery cell 20 during thermal runaway is shorter, the pressure relief of the battery cell 20 during thermal runaway is more timely, and the number of cycle fatigue of the battery cell 20 is greater. The priority initiation area 2142 is less likely to be affected by pressure changes inside the battery cell 20, causing the pressure relief component 214 to rupture prematurely along the priority initiation area 2142, and the battery cell 20 has a longer lifespan.

[0205] The first weak portion 2145 has a priority initiation area 2142. When the battery cell 20 is depressurized, the priority initiation area 2142 first ruptures, followed by a gradual rupture of other areas of the first weak portion 2145 along the extension direction of the first weak portion 2145. When D ≥ 0.05 mm, the minimum thickness of the priority initiation area 2142 is greater, making it less likely to prematurely rupture due to pressure changes within the battery cell 20 or external impacts, thereby improving the lifespan of the battery cell 20. When D ≤ 0.6 mm, the minimum thickness of the priority initiation area 2142 is not excessively large, allowing the priority initiation area 2142 to rupture promptly when the battery cell 20 is depressurized, thereby improving the timeliness of the pressure release of the battery cell 20. Therefore, when 0.05mm≤D≤0.6mm, the priority initiation zone 2142 is not easily cracked due to pressure changes within the battery cell 20 or external impacts, and the priority initiation zone 2142 is easily cracked in a timely manner, which is beneficial to improving the timeliness of pressure relief of the battery cell 20. When L2≥5mm, the minimum distance between the projection of the priority initiation zone 2142 along the thickness direction of the first wall portion 211 on the first outer surface 2111 and the center point of the first outer surface 2111 is larger, and the rigidity of the location of the priority initiation zone 2142 is greater. During normal use of the battery cell 20, the priority initiation zone 2142 is not easily cracked prematurely due to pressure changes within the battery cell 20 or external impacts, which is beneficial to reducing the risk of premature damage to the priority initiation zone 2142. When L2 ≤ 40 mm, the minimum distance between the projection of the priority initiation zone 2142 along the thickness direction of the first wall portion 211 on the first outer surface 2111 and the center point of the first outer surface 2111 is not excessively large. When the battery cell 20 releases internal pressure, the priority initiation zone 2142 undergoes significant deformation under the action of gas, allowing the priority initiation zone 2142 to rupture promptly, thereby improving the timeliness of pressure release from the battery cell 20. Therefore, when 5 mm ≤ L2 ≤ 40 mm, the priority initiation zone 2142 is not easily ruptured by changes in gas pressure within the battery cell 20 or external impacts, but also facilitates its timely rupture, thereby improving the timeliness of pressure release from the battery cell 20.

[0206] Optionally, 0.1mm≤D≤0.5mm.

[0207] The minimum thickness of the priority detonation area 2142 can be: D = 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, etc.

[0208] When D ≥ 0.1 mm, the risk of the priority ignition zone 2142 cracking due to changes in air pressure inside the battery cell 20 or external impact can be further reduced, which is beneficial to improving the life of the battery cell 20. When D ≤ 0.5 mm, the priority ignition zone 2142 can crack more promptly when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure release of the battery cell 20. Therefore, when 0.1 mm ≤ D ≤ 0.5 mm, the priority ignition zone 2142 is less likely to crack due to changes in air pressure inside the battery cell 20 or external impact. At the same time, the priority ignition zone 2142 can crack more promptly when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure release of the battery cell 20.

[0209] Optionally, 10mm≤L2≤30mm.

[0210] The minimum distance between the projection of the priority detonation zone 2142 along the thickness direction of the first wall portion 211 on the first outer surface 2111 and the center point of the first outer surface 2111 can be: L2 = 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, etc.

[0211] When L2 ≥ 10mm, the rigidity of the location of the priority ignition zone 2142 is greater, and the priority ignition zone 2142 is less likely to crack prematurely due to pressure changes inside the battery cell 20 or external impacts, which helps reduce the risk of the priority ignition zone 2142 being damaged prematurely. When L2 ≤ 30mm, when the battery cell 20 releases internal pressure, the priority ignition zone 2142 undergoes a significant deformation under the action of the gas, allowing the priority ignition zone 2142 to crack more promptly, which helps improve the timeliness of the pressure relief of the battery cell 20. Therefore, when 10mm ≤ L2 ≤ 30mm, the priority ignition zone 2142 is not only less likely to crack due to pressure changes inside the battery cell 20 or external impacts, but also facilitates the priority ignition zone 2142 to crack in a timely manner, which helps improve the timeliness of the pressure relief of the battery cell 20.

[0212] Please refer to Figure 9, which is a bottom view of the housing 21 of the battery cell 20 provided in some other embodiments of the present application. In some other embodiments, the pressure relief component 214 is provided with a first groove 2141, and the pressure relief component 214 forms a first weak portion 2145 in the area where the first groove 2141 is provided. The first groove 2141 includes a first groove section 2141a and a second groove section 2141b, and the first groove section 2141a and the second groove section 2141b are connected. The centerline of the groove bottom surface of the first groove section 2141a and the centerline of the groove bottom surface of the second groove section 2141b intersect at a first intersection 21421. The extension direction of the centerline of the groove bottom surface of the first groove section 2141a is parallel to the extension direction of the first groove section 2141a, and the extension direction of the centerline of the groove bottom surface of the second groove section 2141b is parallel to the extension direction of the second groove section 2141b. The area of ​​the first weak portion 2145 within the range of radius R with the first intersection point 21421 as the center is the priority detonation area 2142, A>R=5mm.

[0213] Along the thickness direction of the first wall portion 211, the first wall portion 211 has a first outer surface 2111 and a first inner surface 2112 that are oppositely disposed. The first outer surface 2111 faces away from the interior of the housing 21, while the first inner surface 2112 faces the interior of the housing 21. The first groove 2141 can be disposed on either the first outer surface 2111 or the first inner surface 2112. Referring to Figures 5 and 6, in the embodiment shown in the figures, the first groove 2141 is disposed on the first outer surface 2111.

[0214] The pressure relief component 214 forms a first weakened portion 2145 in the region where the first groove 2141 is provided. This can also be understood as the first weakened portion 2145 being formed on the bottom wall of the first groove 2141. Referring to Figures 5 and 6 , in the embodiment shown in the figures, along the thickness direction of the first wall 211, the first weakened portion 2145 is the portion of the pressure relief component 214 located between the bottom surface of the first groove 2141, which is furthest from the first outer surface 2111, and the first inner surface 2112.

[0215] The first groove 2141 can be formed using a variety of methods, such as stamping, cold heading, and the like. Stamping or cold heading the first groove 2141 causes the groove wall of the first groove 2141 to undergo cold work hardening (changing the grain arrangement, causing lattice distortion, reducing the metal's plasticity, and increasing the material's hardness). This enhances its ability to resist external impact and makes it less susceptible to damage from external impact. This helps reduce the risk of leakage from the pressure relief component 214.

[0216] The first groove 2141 includes a first groove section 2141a and a second groove section 2141b, which are connected. For example, in FIG9 , one end of the first groove section 2141a is connected to one end of the second groove section 2141b, and both the first groove section 2141a and the second groove section 2141b are straight groove sections, so that the first groove section 2141a and the second groove section 2141b form an "L"-shaped first groove 2141. Of course, in other embodiments, one end of the first groove section 2141a may also be connected to the middle of the second groove section 2141b.

[0217] The center line of the bottom surface of the first slot segment 2141a is located in the middle of the bottom surface of the first slot segment 2141a in the width direction of the first slot segment 2141a. The extension direction of the center line of the bottom surface of the first slot segment 2141a is parallel to the extension direction of the first slot segment 2141a.

[0218] The center line of the bottom surface of the second slot segment 2141b is located in the middle of the bottom surface of the second slot segment 2141b in the width direction of the second slot segment 2141b. The extension direction of the center line of the bottom surface of the second slot segment 2141b is parallel to the extension direction of the second slot segment 2141b.

[0219] The first intersection 21421 is the intersection of the centerline of the bottom surface of the first groove section 2141a and the centerline of the bottom surface of the second groove section 2141b. The area of ​​the first weak portion 2145 within the circular range with a radius of 5 mm and centered at the first intersection 21421 is the aforementioned priority detonation zone 2142.

[0220] It should be noted that the minimum radial dimension of the first outer surface 2111 is greater than 5 mm.

[0221] The stress at the intersection of the first groove section 2141a and the second groove section 2141b is more concentrated. The area of ​​the first weak portion 2145 within the range of 5 mm in radius with the first intersection point 21421 as the center is the priority ignition zone 2142. When the battery cell 20 is depressurized, the priority ignition zone 2142 is cracked first, and then the first groove section 2141a and the second groove section 2141b are gradually cracked along their extension direction, thereby realizing rapid depressurization of the battery cell 20.

[0222] Referring again to Figures 5 and 6, first groove 2141 includes a third groove section 2141c. First groove section 2141a and third groove section 2141c are disposed opposite each other, and second groove section 2141b connects first groove section 2141a and third groove section 2141c. The centerline of the groove bottom of second groove section 2141b intersects with the centerline of the groove bottom of third groove section 2141c at a second intersection point 21422. The centerline of the groove bottom of third groove section 2141c extends parallel to the direction of extension of third groove section 2141c. The area of ​​first weak portion 2145 within a radius R centered at second intersection point 21422 serves as a priority detonation zone 2142.

[0223] The first slot section 2141a and the third slot section 2141c are spaced apart and at least partially opposed to each other. The second slot section 2141b connects the first slot section 2141a and the third slot section 2141c. That is, the second slot section 2141b is located between the first slot section 2141a and the third slot section 2141c, and the two ends of the second slot section 2141b are connected to the first slot section 2141a and the third slot section 2141c, respectively. Of course, in other embodiments, the two ends of the second slot section 2141b can extend from the first slot section 2141a and the third slot section 2141c, respectively.

[0224] Please refer to Figures 5 and 6. In the embodiments shown in the figures, the connection position between the second slot segment 2141b and the first slot segment 2141a deviates from the two ends of the first slot segment 2141a. That is, the second slot segment 2141b is connected between the two ends of the first slot segment 2141a. Similarly, the connection position between the third slot segment 2141c and the second slot segment 2141b deviates from the two ends of the third slot segment 2141c. That is, the second slot segment 2141b is connected between the two ends of the third slot segment 2141c. Therefore, the shape of the first groove 2141 formed by the first slot segment 2141a, the second slot segment 2141b and the third slot segment 2141c is approximately an "H"-shaped structure.

[0225] The center line of the bottom surface of the third slot segment 2141c is located in the middle of the bottom surface of the third slot segment 2141c in the width direction of the third slot segment 2141c. The extension direction of the center line of the bottom surface of the third slot segment 2141c is parallel to the extension direction of the third slot segment 2141c.

[0226] The second intersection 21422 is the intersection of the centerline of the bottom surface of the second groove section 2141b and the centerline of the bottom surface of the third groove section 2141c. The area of ​​the first weak portion 2145 within the circular range with a radius of 5 mm and centered at the second intersection 21422 is the aforementioned priority detonation zone 2142.

[0227] Please refer to Figure 5. In the embodiment shown in Figure 5, the first weak portion 2145 includes two priority ignition areas 2142. The area of ​​the first weak portion 2145 within the circular range with the first intersection 21421 as the center and a radius of 5 mm is one priority ignition area 2142, and the area of ​​the first weak portion 2145 within the circular range with the second intersection 21422 as the center and a radius of 5 mm is another priority ignition area 2142. The above two priority ignition areas 2142 are arranged at intervals, that is, in the embodiment shown in Figure 5, the distance between the first intersection 21421 and the second intersection 21422 is greater than 10 mm.

[0228] The stress at the intersection of the second groove section 2141b and the third groove section 2141c is more concentrated. The area of ​​the first weak portion 2145 within the range of 5 mm in radius with the second intersection point 21422 as the center is also the priority ignition zone 2142. When the battery cell 20 is depressurized, the two priority ignition zones 2142 first crack, and then the first groove section 2141a, the second groove section 2141b and the third groove section 2141c gradually crack along their extension direction, thereby realizing rapid depressurization of the battery cell 20.

[0229] 5 , 6 , 7 and 8 , in some embodiments, the maximum radial dimension of the first outer surface 2111 is B, satisfying: B≥A≥10 mm.

[0230] B represents the maximum radial dimension of the first outer surface 2111. The "maximum radial dimension of the first outer surface 2111" refers to the dimension of the longest straight line segment among a plurality of straight line segments that have any two points on the outer edge of the first outer surface 2111 as endpoints and pass through the center point of the first outer surface 2111. Please refer to Figures 5 and 6. In the embodiments shown in Figures 5 and 6, the first outer surface 2111 is a rectangular structure, and the maximum radial dimension of the first outer surface 2111 is the length of the diagonal of the rectangle. Please refer to Figures 7 and 8. In the embodiments shown in Figures 7 and 8, the first outer surface 2111 is a circular structure, and the maximum radial dimension of the first outer surface 2111 is the diameter of the circular surface. For example, in some embodiments, the first outer surface 2111 is a regular hexagon, and the maximum radial dimension of the first outer surface 2111 is the length of the diagonal of the regular hexagon.

[0231] When A ≥ 10 mm, the minimum radial dimension of the first outer surface 2111 is larger, and the stiffness of the first wall portion 211 near the outer edge of the first outer surface 2111 differs significantly from the stiffness of the first wall portion 211 near the center of the first outer surface 2111. In this case, positioning the first weak portion 2145 within the first edge 2143 achieves better results. The maximum radial dimension of the first outer surface 2111 can be equal to the minimum radial dimension of the first outer surface 2111. For example, when the first outer surface 2111 is a circular structure, the maximum radial dimension of the first outer surface 2111 and the minimum radial dimension of the first outer surface 2111 are both the diameter of the circular structure. The maximum radial dimension of the first outer surface 2111 can be greater than the minimum radial dimension of the first outer surface 2111. For example, when the first outer surface 2111 is a rectangular structure, the maximum radial dimension of the first outer surface 2111 is the length of the diagonal of the rectangular structure, and the minimum radial dimension of the first outer surface 2111 is the width of the rectangular structure.

[0232] 5 and 6 , in some embodiments, the thickness of the region of the pressure relief component 214 where the first weak portion 2145 is not provided is D1 , satisfying the following: 0.1 mm ≤ D1 ≤ 10 mm.

[0233] D1 represents the thickness of the region of the pressure relief component 214 where the first weak portion 2145 is not provided. The thickness of the region of the pressure relief component 214 where the first weak portion 2145 is not provided can be obtained through tomography.

[0234] The thickness of the area of ​​the pressure relief component 214 where the first weak portion 2145 is not provided can be: D1 = 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, etc.

[0235] When D1 ≥ 0.1 mm, the thickness of the area of ​​the pressure relief component 214 not provided with the first weak portion 2145 is greater, and the minimum thickness of the first weak portion 2145 provided in the pressure relief component 214 can also be greater. This prevents the first weak portion 2145 from prematurely cracking due to pressure changes within the battery cell 20 or external impact during normal use of the battery cell 20, thereby reducing the risk of premature damage to the first weak portion 2145 and improving the lifespan of the battery cell 20. When D1 ≤ 10 mm, the thickness of the area of ​​the pressure relief component 214 not provided with the first weak portion 2145 is not excessive, and less material needs to be removed during machining of the first weak portion 2145, thereby reducing material waste and simplifying machining. Therefore, when 0.1 mm ≤ D1 ≤ 10 mm, the thickness of the machined first weak portion 2145 can be optimized, reducing the risk of premature damage to the first weak portion 2145 and improving the lifespan of the battery cell 20. This also reduces material waste and reduces machining difficulty.

[0236] 7 and 8 , in some embodiments, the housing 21 includes a second wall portion 212 adjacent to the first wall portion 211 , and the second wall portion 212 and the first wall portion 211 are directly connected.

[0237] The second wall portion 212 is adjacent to the first wall portion 211. In the embodiment shown in Figures 7 and 8, the second wall portion 212 is a circumferential wall of a cylindrical structure. In this case, the second wall portion 212 is directly connected to the first wall portion 211 without the need for a rounded transition.

[0238] The second wall portion 212 is directly connected to the first wall portion 211 , and there is no need to use a rounded transition between the second wall portion 212 and the first wall portion 211 , which makes manufacturing simpler and more convenient.

[0239] In other embodiments, the second wall portion 212 and the first wall portion 211 have rounded transitions.

[0240] 3 , 4 , and 5 , the housing 21 includes a shell 215 and an end cap 216 . The shell 215 has an opening 2151 formed at at least one end. The end cap 216 corresponds to the opening 2151 and closes the opening 2151. The at least one wall of the shell 215 is a first wall portion 211 .

[0241] The shell 215 includes an integrally formed side wall and bottom wall, that is, the shell 215 is manufactured using an integral molding process, such as an integral molding process such as stamping, casting or extrusion molding. In other words, the side wall and bottom wall of the shell 215 are an integral structure.

[0242] The housing 215 includes a first wall portion 211. That is, the first wall portion 211 is a wall of the housing 215. For example, in FIG5 , the first wall portion 211 is a bottom wall of the housing 215 disposed opposite the end cap 216 in the thickness direction of the first wall portion 211. Of course, in other embodiments, the first wall portion 211 may also be a side wall of the housing 215.

[0243] When the shell 215 includes the first wall portion 211 , the pressure relief component 214 is disposed on a wall of the shell 215 . The fluid medium ejected by the pressure relief component 214 is less likely to act on other electrical connection structures on the end cover 216 , thereby reducing the risk of short circuit of the battery cell 20 .

[0244] In some embodiments, the thickness of the region of the pressure relief component 214 where the first weak portion 2145 is not provided is smaller than the thickness of the end cap 216 .

[0245] By making the thickness of the region of the pressure relief component 214 where the first weak portion 2145 is not provided smaller than the thickness of the end cover 216 , it is easier to release pressure from the pressure relief component 214 when the battery cell 20 is depressurized.

[0246] In other embodiments, the battery cell 20 may also have other structures. For example, the outer shell 21 may include a shell 215 and an end cover 216. The interior of the shell 215 forms a accommodating cavity with an opening 2151, which is used to accommodate the electrode assembly 22. The end cover 216 closes the opening 2151, and the end cover 216 is the first wall portion 211.

[0247] It should be noted that the structure of the battery cell 20 can be various. In some embodiments, the outer shell 21 may include a shell 215 and two end covers 216. A accommodating cavity is formed inside the shell 215, and the accommodating cavity is used to accommodate the electrode assembly 22. The shell 215 is formed with openings 2151 at both ends in the thickness direction of the first wall portion 211, and the two openings 2151 are connected to the accommodating cavity. The two end covers 216 respectively close the two openings 2151, and one of the two end covers 216 is the first wall portion 211.

[0248] The shell 215 of the outer shell 21 is provided with openings 2151 at both ends in the thickness direction of the first wall portion 211, and the two end covers 216 respectively close the two openings 2151. The first wall portion 211 is one of the two end covers 216. The battery cell 20 adopting this structure is convenient for assembling the battery cell 20 from both ends of the shell 215, which is beneficial to reducing the manufacturing difficulty and assembly difficulty of the battery cell 20.

[0249] In some embodiments, the pressure relief component 214 is integrally formed with the first wall portion 211 .

[0250] Integrally formed means that the first wall portion 211 and the pressure relief component 214 are an integral structure when provided. For example, the pressure relief component 214 can be formed on the first wall portion 211 by stamping or cold heading.

[0251] Integrating the pressure relief component 214 with the first wall portion 211 eliminates the need for additional welding or bonding processes, which helps reduce the risk of leakage from the pressure relief component 214. Furthermore, during production, the detonation pressures of the multiple battery cells 20 produced can be made more consistent.

[0252] In other embodiments, the pressure relief component 214 is provided separately from the first wall portion 211 , the first wall portion 211 is provided with a pressure relief hole, and the pressure relief component 214 is installed on the first wall portion 211 and covers the pressure relief hole.

[0253] The phrase "pressure relief component 214 is provided separately from first wall portion 211, with a pressure relief hole provided in first wall portion 211, and pressure relief component 214 is mounted on first wall portion 211 and covers the pressure relief hole" means that during manufacturing, a pressure relief hole is provided in first wall portion 211, and pressure relief component 214 and first wall portion 211 are provided separately and ultimately connected together. For example, pressure relief component 214 can be welded to first wall portion 211. Pressure relief component 214 can be a bursting disk mounted on first wall portion 211.

[0254] The pressure relief component 214 is provided separately from the first wall portion 211 and is installed on the first wall portion 211 , thereby facilitating processing and manufacturing.

[0255] According to some embodiments of the present application, the pressure relief component 214 is made of steel.

[0256] It is understood that in the embodiment where the pressure relief component 214 is integrally formed with the first wall portion 211, the material of the first wall portion 211 includes steel. If the first wall portion 211 is the end cap 216 of the housing 21, the end cap 216 is made of steel; if the first wall portion 211 is a wall of the shell 215, the shell 215 is made of steel.

[0257] Exemplarily, the material of the first wall portion 211 may be carbon steel, alloy steel, stainless steel, or the like.

[0258] In this embodiment, by setting the material of the first wall portion 211 to steel, due to the high strength of steel, the first wall portion 211 made of steel has better strength, so that when the bursting pressure of the battery cell 20 is constant, the first wall portion 211 can be made thinner, which is beneficial to saving the space occupied by the first wall portion 211.

[0259] In some embodiments, the steel material is carbon steel or stainless steel.

[0260] Illustratively, the carbon steel may be low carbon steel, medium carbon steel, or high carbon steel.

[0261] In this embodiment, carbon steel or stainless steel is used as the material of the first wall portion 211 , which is low in cost and easy to manufacture.

[0262] In some embodiments, the pressure relief component 214 is made of aluminum alloy.

[0263] It is understood that in embodiments where the pressure relief component 214 is integrally formed with the first wall portion 211, the material of the first wall portion 211 includes an aluminum alloy. If the first wall portion 211 is an end cap 216, the end cap 216 may be made of an aluminum alloy; if the first wall portion 211 is a wall portion within the housing 215, the housing 215 may also be made of an aluminum alloy.

[0264] Aluminum alloy is lightweight and ductile, making it easier to form the first groove 2141 on the pressure relief component 214. In the embodiment where the pressure relief component 214 and the first wall portion 211 are integrally formed, the first wall portion 211 is made of aluminum alloy, which can effectively reduce the difficulty of forming the first wall portion 211.

[0265] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other individual elements ≤ 0.03%.

[0266] This aluminum alloy belongs to the third series aluminum, has lower hardness and better forming ability, reduces the difficulty of processing the first groove 2141, is conducive to improving the processing accuracy of the first groove 2141, and improves the pressure relief consistency of the pressure relief component 214.

[0267] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 96.7%, 0.05% ≤ copper ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other individual element components ≤ 0.05%, and the total composition of other elements ≤ 0.15%.

[0268] This aluminum alloy belongs to the fifth series aluminum. The pressure relief component 214 made of this aluminum alloy has higher hardness, greater strength, and good anti-destruction ability. The embodiment of the present application also provides a battery 100, which includes the battery cell 20 described above.

[0269] An embodiment of the present application further provides an electrical device, which includes the above-mentioned battery cell 20.

[0270] According to some embodiments of the present application, please refer to Figures 3 to 9.

[0271] An embodiment of the present application provides a battery cell 20, comprising a housing 21 and a pressure relief component 214. The housing 21 has a first wall 211, which has a first outer surface 2111 facing away from the interior of the housing 21. The pressure relief component 214 is disposed on the first wall 211. The pressure relief component 214 includes a first weakened portion 2145. The pressure relief component 214 is configured to rupture along at least a portion of the first weakened portion 2145 when the battery cell 20 releases pressure. The first outer surface 2111 has a minimum radial dimension A, where radial refers to a direction passing through the center of the first outer surface 2111. The outer edge of the first outer surface 2111 is offset from the center of the first outer surface 2111 by a predetermined distance L1 to form a first edge 2143, where L1 = 0.05*A. Along the thickness direction of the first wall 211, the projection of the first weakened portion 2145 onto the first outer surface 2111 is located within the first edge 2143. The outer edge of the first outer surface 2111 is offset by 0.05Å toward the center of the first outer surface 2111 to form a first edge 2143. This first edge 2143 defines a first region 2144 on the first wall portion 211. The first region 2144 is located near the center of the wall portion. This region has relatively low rigidity and is less resistant to deformation. When the battery cell 20 releases internal pressure, the first region 2144 undergoes significant deformation under the action of the gas, making the first weak portion 2145 located in the first region 2144 susceptible to deformation and failure. Therefore, under the same detonation pressure, the thickness of the first weak portion 2145 located in the first region 2144 can be increased. This reduces the risk of premature rupture of the first weak portion 2145 due to internal pressure fluctuations or external impact during normal use of the battery cell 20, thereby reducing the risk of premature failure of the first weak portion 2145 and improving the lifespan of the battery cell 20. Furthermore, the greater the thickness of the first weak portion 2145 , the easier it is to manufacture, and the lower the precision requirement for manufacturing equipment.

[0272] In some embodiments, the housing 21 is cylindrical and includes a second wall portion 212, which surrounds the first wall portion 211. The first outer surface 2111 is circular, and the minimum radial dimension of the first outer surface 2111 is the diameter of the circular surface. If the housing 21 is cylindrical and the second wall portion 212 surrounds the first wall portion 211, the second wall portion 212 is the circumferential wall of the housing 21, and the first wall portion 211 is connected to one end of the second wall portion 212. In this case, the first outer surface 2111 is circular, the minimum radial dimension of the first outer surface 2111 is the diameter of the circular surface, and the first edge 2143 is a circle with a diameter of 0.9A.

[0273] In other embodiments, the housing 21 has a prismatic structure, and the first outer surface 2111 has a rectangular structure. The first outer surface 2111 includes two first long sides 21111 and two first short sides 21112. The two first long sides 21111 are arranged opposite each other along the width direction of the first wall portion 211, and the two first short sides 21112 are arranged opposite each other along the length direction of the first wall portion 2111. The two first long sides 21111 and the two first short sides 21112 are offset from the center point of the first outer surface 2111 by a predetermined distance L1 to form a first edge 2143. The first edge 2143 has a rectangular structure, with the long sides of the first edge 2143 being formed by the two first long sides 21111 of the first outer surface 2111 offset from the center point of the first outer surface 2111, and the short sides of the first edge 2143 being formed by the two first short sides 21112 of the first outer surface 2111 offset from the center point of the first outer surface 2111.

[0274] The first weak portion 2145 includes at least one preferential initiation zone 2142. This preferential initiation zone 2142 ruptures before other areas of the first weak portion 2145 when the battery cell 20 is depressurized. The minimum distance between the projection of the preferential initiation zone 2142 on the first outer surface 2111 along the thickness direction of the first wall 211 and the center point of the first outer surface 2111 is L2. The minimum thickness of the preferential initiation zone 2142 is D, satisfying the following conditions: 5mm≤L2≤40mm, 0.05mm≤D≤0.6mm. The first weak portion 2145 has the preferential initiation zone 2142. When the battery cell 20 is depressurized, the preferential initiation zone 2142 ruptures first, followed by the gradual rupture of other areas of the first weak portion 2145 along the extension direction of the first weak portion 2145. When D ≥ 0.05 mm, the minimum thickness of the priority initiation zone 2142 is greater, making it less likely for the priority initiation zone 2142 to prematurely rupture due to changes in air pressure within the battery cell 20 or external impacts, which is beneficial for improving the lifespan of the battery cell 20. When D ≤ 0.6 mm, the minimum thickness of the priority initiation zone 2142 is not too large, allowing the priority initiation zone 2142 to rupture promptly when the battery cell 20 is depressurized, which is beneficial for improving the timeliness of the pressure relief of the battery cell 20. Therefore, when 0.05 mm ≤ D ≤ 0.6 mm, the priority initiation zone 2142 is not likely to rupture due to changes in air pressure within the battery cell 20 or external impacts, and it is also easier for the priority initiation zone 2142 to rupture promptly, which is beneficial for improving the timeliness of the pressure relief of the battery cell 20. When L2 is ≥ 5 mm, the minimum distance between the projection of the preferential initiation zone 2142 along the thickness direction of the first wall portion 211 onto the first outer surface 2111 and the center point of the first outer surface 2111 is greater, and the rigidity of the location of the preferential initiation zone 2142 is greater. During normal use of the battery cell 20, the preferential initiation zone 2142 is less likely to prematurely rupture due to pressure changes within the battery cell 20 or external impacts, thereby reducing the risk of premature damage to the preferential initiation zone 2142. When L2 is ≤ 40 mm, the minimum distance between the projection of the preferential initiation zone 2142 along the thickness direction of the first wall portion 211 onto the first outer surface 2111 and the center point of the first outer surface 2111 is not excessively large. When the battery cell 20 releases internal pressure, the preferential initiation zone 2142 undergoes significant deformation under the action of gas, allowing the preferential initiation zone 2142 to rupture promptly, thereby improving the timeliness of pressure release in the battery cell 20. Therefore, when 5mm≤L2≤40mm, the priority ignition area 2142 is not easily cracked due to pressure changes inside the battery cell 20 or external impact, and the priority ignition area 2142 is easy to crack in time, which is beneficial to improving the timeliness of pressure relief of the battery cell 20.

[0275] The pressure relief component 214 is provided with a first groove 2141. A first weakened portion 2145 is formed in the area where the first groove 2141 is located. The first groove 2141 comprises a first groove section 2141a and a second groove section 2141b, which are connected. The centerline of the bottom surface of the first groove section 2141a intersects with the centerline of the bottom surface of the second groove section 2141b at a first intersection point 21421. The centerline of the bottom surface of the first groove section 2141a extends parallel to the direction of extension of the first groove section 2141a, and the centerline of the bottom surface of the second groove section 2141b extends parallel to the direction of extension of the second groove section 2141b. The area of ​​the first weakened portion 2145 within a radius R centered at the first intersection point 21421 serves as a priority detonation zone 2142, where A > R = 5 mm. The stress at the intersection of the first groove section 2141a and the second groove section 2141b is more concentrated. The area of ​​the first weak portion 2145 within the range of 5 mm in radius with the first intersection point 21421 as the center is the priority ignition zone 2142. When the battery cell 20 is depressurized, the priority ignition zone 2142 is cracked first, and then the first groove section 2141a and the second groove section 2141b are gradually cracked along their extension direction, thereby realizing rapid depressurization of the battery cell 20.

[0276] The first groove 2141 includes a third groove section 2141c. The first groove section 2141a and the third groove section 2141c are arranged opposite each other, and the second groove section 2141b connects the first groove section 2141a and the third groove section 2141c. The centerline of the groove bottom of the second groove section 2141b intersects the centerline of the groove bottom of the third groove section 2141c at a second intersection point 21422. The centerline of the groove bottom of the third groove section 2141c extends parallel to the extension direction of the third groove section 2141c. The area of ​​the first weak portion 2145 within a radius R centered at the second intersection point 21422 serves as the priority detonation zone 2142. The stress at the intersection of the second groove section 2141b and the third groove section 2141c is more concentrated. The area of ​​the first weak portion 2145 within the range of 5 mm in radius with the second intersection point 21422 as the center is also the priority ignition zone 2142. When the battery cell 20 is depressurized, the two priority ignition zones 2142 first crack, and then the first groove section 2141a, the second groove section 2141b and the third groove section 2141c gradually crack along their extension direction, thereby realizing rapid depressurization of the battery cell 20.

[0277] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, wherein, Comprising: A housing having a first wall portion with a first outer surface facing away from the interior of the housing; A pressure relief component disposed on the first wall portion, the pressure relief component including a first weak portion, and the pressure relief component being configured to be able to crack along at least a part of the first weak portion when the battery cell relieves pressure; The minimum radial dimension of the first outer surface is A, where the radial direction refers to the direction passing through the center point of the first outer surface, and the outer edge of the first outer surface is offset by a predetermined distance L1 towards the center point of the first outer surface to form a first edge, and L1 = 0.05 * A; In the thickness direction of the first wall portion, the projection of the first weak portion on the first outer surface is located within the first edge.

2. The battery cell according to claim 1, wherein, The housing is a cylindrical structure, the housing includes a second wall portion surrounding the first wall portion, the first outer surface is a circular structure, and the minimum radial dimension of the first outer surface is the diameter of the circular surface.

3. The battery cell according to claim 1, wherein, The housing is a prismatic structure, the first outer surface is a rectangular structure, the first outer surface includes two first long sides and two first short sides, the two first long sides are oppositely arranged in the width direction of the first wall portion, the two first short sides are oppositely arranged in the length direction of the first wall portion, and the two first long sides and the two first short sides are offset by the predetermined distance L1 towards the center point of the first outer surface to form the first edge.

4. The battery cell according to any one of claims 1-3, wherein, The first weak portion includes at least one preferential initiation area that cracks earlier than other areas of the first weak portion when the battery cell relieves pressure. The minimum distance between the projection of the preferential initiation area on the first outer surface in the thickness direction of the first wall portion and the center point of the first outer surface is L2, and the minimum thickness of the preferential initiation area is D, satisfying: 5mm ≤ L2 ≤ 40mm, 0.05mm ≤ D ≤ 0.6mm.

5. The battery cell according to claim 4, wherein, 0.1mm ≤ D ≤ 0.5mm.

6. The battery cell according to claim 4 or 5, wherein, 10mm ≤ L2 ≤ 30mm.

7. The battery cell according to any one of claims 4-6, wherein, The pressure relief component is provided with a first groove, and the first weak portion is formed in the area where the first groove is provided. The first groove includes a first groove section and a second groove section, the first groove section and the second groove section are connected, the center line of the bottom surface of the first groove section intersects the center line of the bottom surface of the second groove section at a first intersection point, the extending direction of the center line of the bottom surface of the first groove section is parallel to the extending direction of the first groove section, the extending direction of the center line of the bottom surface of the second groove section is parallel to the extending direction of the second groove section, and the area within a range with the first intersection point as the center and a radius of R is the preferential initiation area, where A > R = 5mm.

8. The battery cell according to claim 7, wherein, The first groove includes a third groove section. The first groove section and the third groove section are oppositely arranged. The second groove section connects the first groove section and the third groove section. The center line of the bottom surface of the second groove section intersects the center line of the bottom surface of the third groove section at a second intersection point. The extending direction of the center line of the bottom surface of the third groove section is parallel to the extending direction of the third groove section. The area within the range with a radius of R centered at the second intersection point of the first weak part is the priority initiation area.

9. The battery cell according to any one of claims 1-8, wherein, The maximum radial dimension of the first outer surface is B, satisfying: B≥A≥10mm.

10. The battery cell according to any one of claims 1-9, wherein, The thickness of the area where the first weak part is not provided on the pressure relief component is D1, satisfying: 0.1mm≤D1≤10mm.

11. The battery cell according to any one of claims 1-10, wherein, The housing includes a second wall portion adjacent to the first wall portion, and the second wall portion is directly connected to the first wall portion.

12. The battery cell according to any one of claims 1-11, wherein, The housing includes: A housing body with an opening formed at at least one end; An end cover corresponding to the opening one by one, and the end cover closes the opening; At least one wall in the housing body is the first wall portion.

13. The battery cell according to claim 12, wherein, The thickness of the area where the first weak part is not provided on the pressure relief component is less than the thickness of the end cover.

14. The battery cell according to any one of claims 1-13, wherein, The material of the pressure relief component includes aluminum material or steel material.

15. The battery cell according to any one of claims 1-14, wherein, The pressure relief component is integrally formed with the first wall portion.

16. The battery cell according to any one of claims 1-14, wherein, The pressure relief component is separately arranged from the first wall portion. The first wall portion is provided with a pressure relief hole, and the pressure relief component is installed on the first wall portion and covers the pressure relief hole.

17. A battery, wherein, Including the battery cell according to any one of claims 1-16.

18. An electrical device, wherein, Including the battery cell according to any one of claims 1-16.

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