Battery monomer, battery and electric equipment

Abstract

The utility model provides a battery monomer, a battery and electric equipment. The battery cell includes a housing having a first wall portion having a first outer surface facing away from an interior of the housing, and a pressure relief member. The pressure relief component is arranged on the first wall part, the pressure relief component comprises a first weak part, and the pressure relief component is configured to be capable of cracking along at least one part of the first weak part when the battery monomer is subjected to pressure relief. 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, the outer edge of the first outer surface deviates towards the center point of the first outer surface by a preset distance L1 to form a first edge, and L1 = 0.05 * A. The projection of the first weak part on the first outer surface is located in the first edge in the thickness direction of the first wall part. The first edge defines the first area with small rigidity, under the same detonation pressure, the thickness of the first weak part located in the first area can be larger, the first weak part is not prone to cracking in advance, and the service life of the single battery is prolonged.

Description

Technical Field

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

[0002] Batteries are widely used in the field of new energy, such as electric vehicles and new energy vehicles. New energy vehicles and electric vehicles have become a new trend in the development of the automotive industry. The development of battery technology must consider many design factors at the same time, such as performance parameters such as energy density, discharge capacity, and charge and discharge rate. In addition, the battery life also needs to be considered. However, the current battery life is short. Utility Model Content

[0003] 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.

[0004] In a first aspect, an embodiment of the present application provides a battery cell, comprising an outer shell and a pressure relief component, wherein the outer shell has a first wall portion, and the first wall portion has a first outer surface facing away from the interior of the outer shell; the pressure relief component is arranged on the first wall portion, and 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 pressure-released; wherein 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, 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.

[0005] 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, and the first area is an area with relatively small rigidity on the wall portion, and its ability to resist deformation is relatively weak. When the battery cell releases the internal pressure, the first area undergoes a large deformation under the action of the gas, and the first weak portion arranged in the first area is easily deformed and damaged. Therefore, under the same detonation pressure, the thickness of the first weak portion arranged in the first area can be larger. In this way, when the battery cell is used normally, the first weak portion is not easy to cause the first weak portion to crack prematurely due to pressure changes inside the battery cell or external impact, which is beneficial to reduce the risk of premature damage to the first weak portion and is beneficial to increase the life of the battery cell. Furthermore, the greater the thickness of the first weak portion, the easier it is to manufacture, and the lower the precision requirements for the manufacturing equipment.

[0006] As an optional technical solution of an embodiment of the present application, the outer shell is a cylindrical structure, the outer 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.

[0007] In the above technical solution, the housing is a cylindrical structure, and the second wall portion is arranged around the first wall portion, then the second wall portion is the peripheral 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.

[0008] 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 relatively arranged along the width direction of the first wall portion, the two first short sides are relatively arranged 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.

[0009] 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.

[0010] 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, and 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, which satisfies: 5mm≤L2≤40mm, 0.05mm≤D≤0.6mm.

[0011] In the above technical solution, the first weak portion has a priority detonation zone. When the battery cell is depressurized, the priority detonation zone is first cracked, and then other areas of the first weak portion are gradually cracked along the extension direction of the first weak portion. When D ≥ 0.05mm, the minimum thickness of the priority detonation zone is relatively large, so that the priority detonation 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 detonation zone is not too large, so that the priority detonation 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 detonation 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 detonation zone to crack in time, which is beneficial to improving the timeliness of the pressure relief of the battery cell. When L2≥5mm, the minimum distance between the projection of the priority detonation zone along the thickness direction of the first wall on the first outer surface and the center point of the first outer surface is large, and the rigidity of the location of the priority detonation zone is large. When the battery cell is in normal use, the priority detonation zone is not easy to crack in advance due to the pressure change inside the battery cell or the external impact, which is conducive to reducing the risk of the priority detonation zone being damaged in advance. When L2≤40mm, the minimum distance between the projection of the priority detonation zone along the thickness direction of the first wall on the first outer surface and the center point of the first outer surface is not too large. When the battery cell releases the internal pressure, the priority detonation zone undergoes a large deformation under the action of the gas, so that the priority detonation zone can be cracked in time, which is conducive to improving the timeliness of the pressure release of the battery cell. Therefore, when 5mm≤L2≤40mm, the priority detonation zone is not easy to crack due to the pressure change inside the battery cell or the external impact, and it is easy for the priority detonation zone to crack in time, which is conducive to improving the timeliness of the pressure release of the battery cell.

[0012] As an optional technical solution of the embodiment of the present application, 0.1mm≤D≤0.5mm.

[0013] In the above technical solution, when D≥0.1mm, the risk of the priority detonation 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 detonation 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 detonation zone is less likely to crack due to changes in air pressure inside the battery cell or external impact, and at the same time, the priority detonation 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.

[0014] As an optional technical solution of an embodiment of the present application, 10mm≤L2≤30mm.

[0015] In the above technical solution, when L2≥10mm, the rigidity of the location of the priority detonation zone is greater, and the priority detonation zone is less likely to crack prematurely due to pressure changes inside the battery cell or external impacts, which is beneficial to reduce the risk of premature damage to the priority detonation zone. When L2≤30mm, when the battery cell releases internal pressure, the priority detonation zone undergoes a large deformation under the action of gas, so that the priority detonation 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 detonation zone is not easy to crack due to changes in air pressure inside the battery cell or external impacts, and it is easy for the priority detonation zone to crack in time, which is beneficial to improving the timeliness of pressure relief of the battery cell.

[0016] 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, 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 intersects with the center line of the groove bottom surface of the second groove section 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, 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.

[0017] 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 portion within the range of 5 mm as the 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 depressurization of the battery cell.

[0018] 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 is the priority detonation zone.

[0019] 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 portion within the range of 5 mm as the radius with the second intersection as the center is also the priority ignition zone. When the battery cell is depressurized, the two priority ignition zones are cracked first, and then the first groove segment, the second groove segment and the third groove segment are gradually cracked along their extension direction, thereby realizing rapid pressure relief of the battery cell.

[0020] 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.

[0021] In the above technical solution, when A≥10mm, 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.

[0022] 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.

[0023] In the above technical solution, when D1≥0.1mm, the thickness of the area where the first weak part is not provided in the pressure relief component is larger, and the minimum thickness of the first weak part provided in the pressure relief component can also be larger. In this way, when the battery cell is in normal use, the first weak part is not easy to be cracked prematurely due to the pressure change inside the battery cell or the external impact, which is beneficial to reduce the risk of the first weak part being damaged prematurely and to improve the life of the battery cell. When D1≤10mm, the thickness of the area where the first weak part is not provided in the pressure relief component is not too large, and there is no need to remove too much material when processing the first weak part, which is beneficial to reduce material waste and processing difficulty. Therefore, when 0.1mm≤D1≤10mm, the thickness of the processed first weak part can be made more appropriate, reducing the risk of the first weak part being damaged prematurely, which is beneficial to improve the life of the battery cell. In addition, it is beneficial to reduce material waste and processing difficulty.

[0024] As an optional technical solution of an embodiment of the present application, the shell includes a second wall portion adjacent to the first wall portion, and the second wall portion is directly connected to the first wall portion.

[0025] 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 transition between the second wall portion and the first wall portion, which is simpler and more convenient during manufacturing.

[0026] 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.

[0027] 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, and 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.

[0028] 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.

[0029] In the above technical solution, by making the thickness of the area 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.

[0030] As an optional technical solution of the embodiment of the present application, the material of the pressure relief component includes aluminum or steel.

[0031] 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 a higher strength. When the battery cell is in normal use, the first weak portion is not easy to crack prematurely due to pressure changes inside the battery cell or external impact, which is beneficial to reduce the risk of the first weak portion being damaged prematurely and to increase the life of the battery cell.

[0032] As an optional technical solution of the embodiment of the present application, the pressure relief component is integrally formed with the first wall portion.

[0033] In the above technical solution, the pressure relief component is integrally formed with the first wall portion, and no additional welding or bonding process is required, which is conducive to reducing the risk of leakage of the pressure relief component. In addition, during production, it is easy to make the detonation pressure of multiple processed battery cells more consistent.

[0034] As an optional technical solution of the embodiment of the present application, 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.

[0035] 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.

[0036] In a second aspect, an embodiment of the present application further provides a battery, which includes the above-mentioned battery cell.

[0037] In a third aspect, an embodiment of the present application further provides an electrical device, wherein the electrical device comprises the above-mentioned battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. 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 related drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0040] Figure 2 An exploded view of the structure of a battery provided in some embodiments of the present application;

[0041] Figure 3 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0042] Figure 4 An exploded view of the structure of a battery cell provided in some embodiments of the present application;

[0043] Figure 5 A bottom view of a housing of a battery cell provided in some embodiments of the present application;

[0044] Figure 6 A partial cross-sectional view of a housing of a battery cell provided in some embodiments of the present application;

[0045] Figure 7 A schematic diagram of the structure of a battery cell provided in some other embodiments of the present application;

[0046] Figure 8 A top view of a housing of a battery cell provided in some other embodiments of the present application;

[0047] Fig. 9 A bottom view of a housing of a battery cell provided in some further embodiments of the present application.

[0048] 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 detonation 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-ear; 23-electrode terminal; 24-current collecting member; 200-controller; 300-motor. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0050] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. 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 and secondary relationship.

[0051] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0052] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0053] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0054] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0055] The term "plurality" used in the present application refers to two or more (including two).

[0056] 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.

[0057] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0058] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0059] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet 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.

[0060] 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 disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0061] 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 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.).

[0062] 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 positive electrode active materials for batteries can also be used. These positive electrode active materials can 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 its modified compounds, etc.

[0063] In some embodiments, the positive electrode may be a foamed metal. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, etc. When the foamed metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foamed metal, but of course, the positive electrode active material may also be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled or / and deposited in the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0064] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0065] As an example, the negative electrode current collector may be a metal foil, a foamed metal 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 foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, etc. The composite current collector may include a polymer material base 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.).

[0066] 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.

[0067] 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 disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0068] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells 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.

[0069] 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.

[0070] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0071] In some embodiments, the separator is a separator membrane. There are many types of separator membranes, and any known porous separator membrane with good chemical stability and mechanical stability can be selected.

[0072] As an example, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or may be attached to the surface of the positive and negative electrodes.

[0073] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0074] In some embodiments, the battery cell further includes an electrolyte, which plays a role in conducting ions between the positive and negative electrodes. The electrolyte can be liquid, gel or solid. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[0075] 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 dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0076] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, 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.

[0077] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0078] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0079] 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, and the like.

[0080] 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.

[0081] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0082] 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.

[0083] In some embodiments, the electrode assembly is a laminate structure.

[0084] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets may be alternately stacked.

[0085] 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.

[0086] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded sections that are stacked.

[0087] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0088] As an example, the separator may be disposed continuously, and may be disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0089] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0090] In some embodiments, the electrode assembly is provided with tabs, which can lead current out of the electrode assembly. The tabs include a positive tab and a negative tab.

[0091] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0092] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes but is not limited to a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc.

[0093] 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.

[0094] 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.

[0095] 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 accommodated in the case.

[0096] 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.

[0097] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0098] Batteries are widely used in the field of new energy, such as electric vehicles and new energy vehicles. New energy vehicles and electric vehicles have become a new trend in the development of the automotive industry. The development of battery technology must consider many design factors at the same time, such as performance parameters such as energy density, discharge capacity, and charge and discharge rate. In addition, the battery life also needs to be considered. However, the current battery life is short.

[0099] For battery cells, in order to improve the reliability of battery cells, the prior art is to weld a pressure relief mechanism on the battery cells, and a weak portion is provided on the pressure relief mechanism, which 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 explosion or fire of the battery cell.

[0100] However, the weak part often cracks prematurely, that is, before the internal pressure of the battery cell reaches the desired detonation pressure of the project, the weak part has already cracked, resulting in premature scrapping of the battery cell and a shorter life of the battery cell.

[0101] In view of this, an embodiment of the present application provides a battery cell, the battery cell includes a shell and a pressure relief component, 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 split 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, 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 from 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.

[0102] 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, and the first area is an area with relatively small rigidity on the wall portion, and its ability to resist deformation is relatively weak. When the battery cell releases the internal pressure, the first area undergoes a large deformation under the action of the gas, and the first weak portion arranged in the first area is easily deformed and damaged. Therefore, under the same detonation pressure, the thickness of the first weak portion arranged in the first area can be larger. In this way, when the battery cell is used normally, the first weak portion is not easy to cause the first weak portion to crack prematurely due to pressure changes inside the battery cell or external impact, which is beneficial to reduce the risk of premature damage to the first weak portion and is beneficial to increase the life of the battery cell. Furthermore, the greater the thickness of the first weak portion, the easier it is to manufacture, and the lower the precision requirements for the manufacturing equipment.

[0103] The battery cells disclosed in the embodiments of the present application can be used in, but not limited to, electrical devices such as vehicles, ships or aircraft. A power supply system comprising the battery cells and batteries disclosed in the present application can be used to form the electrical device, which is beneficial to prolong the life of the battery cells.

[0104] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, 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., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0105] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device in an embodiment of the present application.

[0106] Please refer to Figure 1 , Figure 1A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided 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 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source or a power source for the vehicle 1000, etc. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for the starting, navigation and working power requirements of the vehicle 1000 during driving.

[0107] In some embodiments of the present application, the battery 100 can not only serve as an operating power source or a use power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0108] Please refer to Figure 2 and Figure 3 , Figure 2 The structure explosion diagram of the battery 100 provided in some embodiments of the present application is shown in FIG. Figure 3 The schematic diagram of the structure of the battery cell 20 provided in some embodiments of the present application is as follows. The battery 100 comprises a box body 10 and a battery cell 20 , and the battery cell 20 is used to be accommodated in the box body 10 .

[0109] The box body 10 is used to provide an assembly space for the battery cell 20, and the box body 10 can adopt a variety of structures. In some embodiments, the box body 10 may include a first box body 11 and a second box body 12, the first box body 11 and the second box body 12 cover each other, and the first box body 11 and the second box body 12 jointly define an assembly space for accommodating the battery cell 20. The second box body 12 may be a hollow structure with one end open, and the first box body 11 may be a plate-like structure, and the first box body 11 covers the open side of the second box body 12, so that the first box body 11 and the second box body 12 jointly define an assembly space; the first box body 11 and the second box body 12 may also be hollow structures with one side open, and the open side of the first box body 11 covers the open side of the second box body 12.

[0110] 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. Figure 2 In the embodiment, the box body 10 is in the shape of a rectangular parallelepiped.

[0111] In the battery 100, the battery cell 20 disposed in the box 10 may be one or more. When there are more than one battery cell 20 disposed in the box 10, the multiple battery cells 20 may be connected in series, in parallel, or in mixed connection. Mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells 20 may be accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in mixed connection, and then the multiple battery modules may be connected in series, in parallel, or in mixed connection to form a whole, and then the whole may be accommodated in the box 10.

[0112] 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 plurality of battery cells 20 to achieve electrical connection between the plurality of battery cells 20 .

[0113] Each battery cell 20 may be a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be in a rectangular parallelepiped, a cylinder, a prism or other shapes. For example, Figure 3 In the figure, the battery cell 20 is a rectangular parallelepiped structure.

[0114] According to some embodiments of this application, please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 , Figure 4 This is a structural explosion diagram of a battery cell 20 provided in some embodiments of the present application. Figure 5 A bottom view of the housing 21 of a battery cell 20 provided in some embodiments of the present application. Figure 6 A partial cross-sectional view of a housing 21 of a battery cell 20 provided in some embodiments of the present application. Figure 7 Schematic diagram of the structure of the battery cell 20 provided in some other embodiments of the present application. Figure 8A top view of the outer shell 21 of a battery cell 20 provided in some other embodiments of the present application. The embodiments of the present application provide a battery cell 20, the battery cell 20 comprising an outer shell 21 and a pressure relief component 214, the outer shell 21 having a first wall portion 211, the first wall portion 211 having 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 portion 211, the pressure relief component 214 comprising a first weak portion 2145, and the pressure relief component 214 is configured to be able to rupture along at least a portion of the first weak portion 2145 when the battery cell 20 is depressurized. The minimum radial dimension of the first outer surface 2111 is A, and 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, wherein L1=0.05*A. Along the thickness direction of the first wall portion 211 , a projection of the first weak portion 2145 on the first outer surface 2111 is located inside the first edge 2143 .

[0115] The battery cell 20 refers to the smallest unit constituting the battery 100 .

[0116] 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 .

[0117] 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 and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved. 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 do not impose special restrictions on 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. Exemplarily, the insulating member can be plastic, rubber, etc.

[0118] The shell 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, the electrolyte and other components. The shell 215 and the end cap 216 can be independent components, and an opening 2151 can be set on the shell 215, and the end cap 216 is covered with the opening 2151 at the opening 2151 to form the internal environment of the battery cell 20. Without limitation, the end cap 216 and the shell 215 can also be integrated. Specifically, the end cap 216 and the shell 215 can form a common joint surface before other components are put into the shell, and when it is necessary to encapsulate the interior of the shell 215, the end cap 216 is covered with the shell 215. The shell 215 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 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.

[0119] The electrode assembly 22 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 22 may be included in the housing 21. The electrode assembly 22 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly 22, and the parts of the positive and negative electrode sheets without active materials each constitute a tab 221. The positive tab and the negative tab may be located together at one end of the main body or at both ends of the main body respectively. During the charge and discharge process of the battery 100, the positive active material and the negative active material react with the electrolyte.

[0120] In some embodiments, see Figure 4 As shown, the battery cell 20 may further include an electrode terminal 23 , which is insulated and mounted on the housing 21 , and is electrically connected to the electrode assembly 22 to output or input electrical energy of the battery cell 20 .

[0121] It should be noted that the electrode terminal 23 is insulated and mounted on the housing 21 , that is, no electrical connection is formed between the electrode terminal 23 and the housing 21 .

[0122] Among them, Figure 3 and Figure 4 In the figure, 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 ears 221, and the polarities of the two pole ears 221 are opposite. The two electrode terminals 23 are electrically connected to the two pole ears 221 of the electrode assembly 22 respectively to realize the input or output of the positive and negative electrodes of the battery cell 20.

[0123] 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.

[0124] Optionally, the electrode terminal 23 may be mounted on the housing 21 in various structures. Figure 3 and Figure 4 In the embodiment, the two electrode terminals 23 are both mounted on the end cap 216 of the outer shell 21. Of course, the structure of the battery cell 20 is not limited thereto. In other embodiments, the two electrode terminals 23 may be both mounted on the shell 215 of the outer shell 21. Similarly, one electrode terminal 23 may be mounted on the shell 215 of the outer shell 21, and the other electrode terminal 23 may be mounted on the end cap 216 of the outer shell 21.

[0125] In some embodiments, see Figure 4 As shown, 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 lugs 221 with the same polarity in the electrode assemblies 22 to achieve electrical connection between the electrode terminal 23 and the electrode assembly 22, which is beneficial to reduce the difficulty of assembly between the lug 221 and the electrode terminal 23.

[0126] Exemplarily, the material of the current collecting component 24 may be various, for example, the material of the current collecting component 24 may be copper, iron, aluminum, steel or aluminum alloy.

[0127] The first wall portion 211 may be an end cover 216 of the housing 21, or may be a wall of the shell 215 of the housing 21. Figure 3 and Figure 4 In the embodiment, the first wall portion 211 is a bottom wall of the housing 215 that is disposed opposite to the end cover 216. In other embodiments, the first wall portion 211 may also be a side wall of the housing 215 that is adjacent to the end cover 216 and connected to each other.

[0128] The first outer surface 2111 is the surface of the first wall portion 211 facing away from the interior of the housing 21, and 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 a 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 a circular surface of the first wall portion 211 facing away from the interior of the housing 21.

[0129] 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, and the first outer surface 2111 can be directly connected to the second outer surface 2121. In this case, an edge is formed at the position where the first outer surface 2111 and the second outer surface 2121 are connected. The first outer surface 2111 can also be connected to the second outer surface 2121 through an arc transition surface 2131. In this case, the first outer surface 2111 and the second outer surface 2121 have a rounded transition.

[0130] The pressure relief component 214 may be a component installed on the first wall portion 211, in which case the pressure relief component 214 is separately arranged and connected to the first wall portion 211. For example, the pressure relief component 214 is an explosion-proof disk installed on the first wall portion 211. The pressure relief component 214 may also be a part of the first wall portion 211, in which case the pressure relief component 214 is integrally formed with the first wall portion 211. The setting position 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 arranged on the end cover 216, the end cover 216 is the first wall portion 211. When the pressure relief component 214 is arranged on the bottom wall of the housing 215, the bottom wall is the first wall portion 211. When the pressure relief component 214 is arranged on the side wall of the housing 215, the side wall is the first wall portion 211.

[0131] The first weak portion 2145 serves to release pressure, and is used to enable the pressure relief component 214 to rupture along the first weak portion 2145 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, so as to release the pressure inside the battery cell 20. In some embodiments, the strength of the pressure relief component 214 at the position of the first weak portion 2145 may be lower than the strength of the pressure relief component 214 at other positions, so that when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, the first weak portion 2145 can rupture under the action of the internal pressure to release the pressure inside the battery cell 20. In other embodiments, the melting point of the pressure relief component 214 at the position of the first weak portion 2145 may be lower than the melting point of the pressure relief component 214 at other positions. In this way, when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, the first weak portion 2145 can rupture under the action of high temperature to release the pressure inside the battery cell 20. Please refer to Figure 6 , in order to facilitate the display of the position of the first weak portion 2145, Figure 6 The cross section of the first weak portion 2145 is shown in a mesh-like filling pattern.

[0132] 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 multiple 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. Figure 5 and Figure 6 ,exist Figure 5 and Figure 6 In the embodiment shown, 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. Figure 7 and Figure 8 ,exist Figure 7 and Figure 8 In the illustrated embodiment, 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.

[0133] The first edge 2143 is formed by the outer edge of the first outer surface 2111 being offset by a predetermined distance L1 toward the center point of the first outer surface 2111. Taking the first outer surface 2111 as a rectangular structure as an example, the first edge 2143 is formed by the two long sides and the two short sides of the first outer surface 2111 being translated toward the intersection of the diagonal lines of the rectangle by a predetermined distance L1. Taking the first outer surface 2111 as a circular structure as an example, the first edge 2143 is formed by the circumference of the first outer surface 2111 being translated toward the center of the circle by a predetermined distance L1.

[0134] 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 .

[0135] Please refer to Figure 5 and Figure 6 , the thickness direction of the first wall portion 211 is the X direction shown in the figure.

[0136] “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 .

[0137] The outer edge of the first outer surface 2111 is offset by 0.05A toward the center point of the first outer surface 2111 to form a first edge 2143, and the first edge 2143 defines a first area 2144 on the first wall portion 211. The first area 2144 is close to the center of the wall portion. The first area 2144 is an area with relatively small rigidity on the wall portion, and its ability to resist deformation is relatively weak. When the battery cell 20 releases the internal pressure, the first area 2144 undergoes a large deformation under the action of the gas, and the first weak portion 2145 arranged in the first area 2144 is easily deformed and damaged. Therefore, under the same detonation pressure, the thickness of the first weak portion 2145 arranged in the first area 2144 can be larger. In this way, when the battery cell 20 is used normally, the first weak portion 2145 is not easy to cause the first weak portion 2145 to crack prematurely due to the pressure change inside the battery cell 20 or the external impact, which is conducive to reducing the risk of premature damage to the first weak portion 2145 and improving the life 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.

[0138] Please refer to Figure 7 and Figure 8 In some embodiments, the housing 21 is a cylindrical structure. The housing 21 includes a second wall portion 212, and the second wall portion 212 is arranged around the first wall portion 211. 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.

[0139] The housing 21 is a cylindrical structure, and the second wall portion 212 is arranged around the first wall portion 211, so the second wall portion 212 is 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 can be an end cover 216, or a bottom wall of the housing 215, and the bottom wall and the end cover 216 are arranged at two ends of the second wall portion 212 opposite to each other.

[0140] 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, and the first edge 2143 is a circle with a diameter of 0.9A.

[0141] Please refer again Figure 5 and Figure 6 In some embodiments, the housing 21 is a prism structure, the first outer surface 2111 is 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 to each other along the width direction of the first wall portion 211, and the two first short sides 21112 are arranged opposite to each other along the length direction of the first wall portion 211. 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.

[0142] The housing 21 is a prism structure, please refer to Figure 5 and Figure 6 ,exist Figure 5 and Figure 6 In the illustrated embodiment, the housing 21 is a quadrangular prism structure, that is, a rectangular parallelepiped structure.

[0143] The first outer surface 2111 is a rectangular structure, and the first outer surface 2111 includes two first long sides 21111 and two first short sides 21112. The first long side 21111 and the first short side 21112 can be directly connected, and in this case, the first long side 21111 and the first short side 21112 form an angle. The first long side 21111 and the first short side 21112 can also be transitioned through an arc segment.

[0144] 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 toward the center point of the first outer surface 2111 by a predetermined distance L1 to form a first edge 2143 .

[0145] 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 the 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).

[0146] 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.

[0147] The first edge 2143 is a rectangular structure, wherein 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.

[0148] Please refer to Figure 5 and Figure 6In some embodiments, the first weak portion 2145 includes at least one priority initiation area 2142, and the priority initiation area 2142 is cracked earlier than other areas of the first weak portion 2145 when the battery cell 20 is depressurized. The minimum distance between the projection of the priority initiation area 2142 on the first outer surface 2111 along the thickness direction of the first wall portion 211 and the center point of the first outer surface 2111 is L2, and the minimum thickness of the priority initiation area 2142 is D, which satisfies: 5mm≤L2≤40mm, 0.05mm≤D≤0.6mm.

[0149] The priority detonation area 2142 is a region of the first weak portion 2145 that is preferentially detonated when the battery cell 20 is depressurized. The priority detonation area 2142 is more likely to crack than other regions of the first weak portion 2145 when the battery cell 20 is depressurized.

[0150] L2 represents the minimum distance between the projection of the priority detonation zone 2142 on the first outer surface 2111 along the thickness direction of the first wall portion 211 and the center point of the first outer surface 2111. The position of the priority detonation zone 2142 can be determined by a thermal runaway experiment, and then the horizontal distance between the priority detonation zone 2142 and the center point of the first outer surface 2111 is measured.

[0151] 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.

[0152] D represents the minimum thickness of the priority detonation zone 2142. The location of the priority detonation zone 2142 can be determined by a thermal runaway experiment, and then the minimum thickness of the priority detonation zone 2142 can be measured. Alternatively, the minimum thickness of the priority detonation zone 2142 can be measured by tomography. It should be noted that the minimum thickness of the priority detonation 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, and can also be less than the minimum thickness of other areas of the first weak portion 2145. Figure 5 and Figure 6 In the illustrated embodiment, the minimum thickness of the preferential detonation zone 2142 is equal to the minimum thickness of other areas of the first weak portion 2145 .

[0153] The minimum thickness of the priority detonation zone 2142 may 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.

[0154] 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 in combination with 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 them. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present application.

[0155] Example 1

[0156] The battery cells 20 in each embodiment and comparative example are prepared and tested according to the following method.

[0157] 1. Preparation of Battery Cell 20

[0158] 1) Preparation of positive electrode

[0159] 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 used to prepare 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 0.1 The 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 stripped, and dried at 85°C under vacuum conditions for 4 hours to make the positive electrode sheet.

[0160] 2) Preparation of negative electrode

[0161] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry is 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC and adhesive styrene butadiene rubber (SBR) in the solid component is 88:7:3:2. The negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C, and then cold pressed, trimmed, cut into pieces, and slit, and then dried at 120°C under vacuum conditions for 12 hours to prepare a negative electrode sheet.

[0162] 3) Preparation of electrolyte

[0163] 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.

[0164] 4) Isolation parts

[0165] A 16 μm polyethylene film was used as a separator.

[0166] 5) Preparation of battery cell 20

[0167] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is located in the middle of the positive and negative electrode sheets to isolate the positive and negative electrodes, and the electrode assembly 22 is wound and placed in an aluminum shell 21. The prepared electrolyte is injected into the dried shell 21, and 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 portion 211 of the shell 21 of the battery cell 20, wherein 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, and the wall opposite to the shell 215 and the end cover 216 is the first wall portion 211, and the first wall portion 211 is a rectangular wall. A first groove 2141 is provided on the first wall portion 211, and the first weak portion 2145 is formed on the first wall portion 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 first weak portion 2145 within the range of radius R with the first intersection 21421 as the center is the priority detonation area 2142, A>R=5mm. The battery cell 20 has a thickness of 39mm, a width of 203mm, a shoulder height (the dimension of the housing 21 in the height direction) of 122.7mm, and a capacity of 185Ah.

[0168] 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.

[0169] 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 ignition 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 ignition zone 2142 are different, as shown in Table 1.

[0170] 2. Performance parameter testing

[0171] 1. Method for measuring the number of cycle fatigue of a battery cell 20

[0172] 1) Prepare a special test fixture. Specifically, the fixture includes three 10 mm steel plates (first steel plate, second steel plate, third steel plate), each of which 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 steel plate and the third steel plate, and the second steel plate is constrained by a guide rail. The second steel plate can only move in translation along the thickness direction of the second steel plate.

[0173] 2) Install the battery cell 20 between the first steel plate and the second steel plate, place a support structure between the two large surfaces of the battery cell 20 and the first steel plate and the second steel plate, the support structure may be a heat insulating 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 may 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 bonded to the support structure, the first steel plate is bonded to the corresponding support structure, the second steel plate is bonded to the corresponding support structure, and a pressure sensor is provided between the second steel plate and the third steel plate.

[0174] 3) The position of the second steel plate is adjusted by adjusting the pre-tightening force of the bolts, and the pressure sensor is observed to make the initial extrusion force on the battery cell 20 2000N, and the positive electrode terminal and the negative electrode terminal of the battery cell 20 are connected to the charging and discharging device.

[0175] 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.

[0176] 5) The test steps are carried out in accordance with Chapter 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 cutoff condition is changed to "stop the test until the first weak portion 2145 provided on the first wall portion 211 is damaged".

[0177] Specifically, test according to the following steps:

[0178] a) Discharge to 2.8v with 1I1(A) current;

[0179] b) Shelving for no less than 30 minutes or under the shelving conditions specified by the enterprise;

[0180] c) Charge according to method 6.1.1.3 of GBT31484-2015 Requirements and test methods for 100 cycle life of power batteries for electric vehicles;

[0181] d) Shelving for no less than 30 minutes or under the shelving conditions specified by the enterprise;

[0182] e) Discharge to 2.8v with a current of 1I1(A);

[0183] 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.

[0184] That is, the test process continuously observes the area where the first groove 2141 is set on the first wall portion 211 of the battery cell 20 until the area is damaged and leaks, and the number of cycles is recorded as the cycle fatigue number of the battery cell 20. Among them, the more cycle fatigue times the battery cell 20 has, the lower the probability of the battery cell 20 opening the valve and leaking due to gas production during long-term use, and the longer the service life.

[0185] 2. Thermal runaway test method for battery cell 20

[0186] 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 (covering area ≥ 60%);

[0187] 2. Charge the battery cell 20 to 100% SOC before testing and ensure that the temperature of the battery cell 20 is 25±5℃;

[0188] 3. Sensor layout:

[0189] 1) Arrangement of temperature sensing wire: A layer of Teflon is attached to the center area of ​​the two large surfaces of the battery cell 20, and a temperature sensing wire is arranged above the Teflon, and then another layer of Teflon is attached;

[0190] 2) Layout of voltage sampling line: A layer of Teflon is attached to the positive electrode terminal, negative electrode terminal and housing 21 of the battery cell 20, a voltage sampling line is arranged above the Teflon, and another layer of Teflon is attached;

[0191] 3) Air pipe arrangement: Drill a hole in the first wall portion 211 of the battery cell 20. The drilling position is located at the midpoint between the first groove 2141 and the side surface of the shell 215 (the outer surface of the wall portion adjacent to the first wall portion 211 along the length direction of the first wall portion 211 of the shell 215), extend the air pipe into the hole and seal it, and connect the air pipe to the air pressure sensor;

[0192] 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 collection frequency of the data acquisition instrument is ≤0.1S;

[0193] 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;

[0194] 5. Test: Open multiple channels to collect temperature, voltage, and air pressure data, and then turn on the heating plate at a power of 500W to heat the battery cell 20 until the battery cell 20 thermally runs away.

[0195] 6. Obtaining the pressure holding time of the battery cell 20: Determine the thermal runaway moment and the valve opening moment according to the temperature, voltage and air pressure data collected from multiple channels, and obtain the pressure holding time of the battery cell 20 according to the pressure holding time = valve opening moment - thermal runaway moment.

[0196] Thermal runaway judgment criteria: a) The trigger object generates a voltage drop, and the voltage drops to more than 25% of the initial voltage; b) The temperature at the detection point reaches the maximum operating temperature specified by the manufacturer; c) The temperature rise rate dT / dt at the detection point is ≥1℃ / s and lasts for more than 3s. When a) and c) or b) and c) occur, it is judged that thermal runaway has occurred and the thermal runaway moment is determined.

[0197] 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), and the moment when the air pressure begins to drop is the valve opening time.

[0198] 3. Test Results

[0199] The experimental results of Comparative Examples 1-2 and Examples 1-7 are shown in Table 1 below:

[0200] Table 1

[0201]

[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 cycle fatigue times of the battery cell 20 are small, and the priority ignition 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 ignition area 2142, and the life of the battery cell 20 is short.

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

[0204] Please refer to Table 1. As shown in Examples 1 to 7, when 5mm≤L2≤40mm and 0.05mm≤D≤0.6mm, 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 times of the battery cell 20 is larger. The priority ignition area 2142 is not easily affected by the pressure change inside the battery cell 20, causing the pressure relief component 214 to crack prematurely along the priority ignition area 2142, and the life of the battery cell 20 is longer.

[0205] The first weak portion 2145 has a priority detonation area 2142. When the battery cell 20 is depressurized, the priority detonation area 2142 is first cracked, and then other areas of the first weak portion 2145 are gradually cracked along the extension direction of the first weak portion 2145. When D ≥ 0.05 mm, the minimum thickness of the priority detonation area 2142 is relatively large, so that the priority detonation area 2142 is not easy to be cracked in advance due to changes in air pressure inside the battery cell 20 or external impact, which is beneficial to improving the life of the battery cell 20. When D ≤ 0.6 mm, the minimum thickness of the priority detonation area 2142 is not too large, so that the priority detonation area 2142 can be cracked in time 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 0.05mm≤D≤0.6mm, the priority detonation area 2142 is not easy to crack due to the pressure change inside the battery cell 20 or the external impact, and it is easy for the priority detonation area 2142 to crack in time, which is beneficial to improve the timeliness of the pressure relief of the battery cell 20. When L2≥5mm, the minimum distance between the projection of the priority detonation area 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 large, and the rigidity of the location of the priority detonation area 2142 is large. When the battery cell 20 is in normal use, the priority detonation area 2142 is not easy to crack in advance due to the pressure change inside the battery cell 20 or the external impact, which is beneficial to reduce the risk of the priority detonation area 2142 being damaged in advance. When L2≤40mm, the minimum distance between the projection of the priority detonation area 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 too large. When the battery cell 20 releases internal pressure, the priority detonation area 2142 undergoes a large deformation under the action of gas, so that the priority detonation area 2142 can be cracked in time, which is beneficial to improving the timeliness of pressure release of the battery cell 20. Therefore, when 5mm≤L2≤40mm, the priority detonation area 2142 is not easy to be cracked due to the change of air pressure inside the battery cell 20 or external impact, and it is easy for the priority detonation area 2142 to be cracked in time, which is beneficial to improving the timeliness of pressure release of the battery cell 20.

[0206] Optionally, 0.1mm≤D≤0.5mm.

[0207] The minimum thickness of the priority detonation zone 2142 may 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≥0.1mm, the risk of the priority detonation area 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≤0.5mm, the priority detonation area 2142 can be cracked more promptly when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the depressurization of the battery cell 20. Therefore, when 0.1mm≤D≤0.5mm, the priority detonation area 2142 is less likely to be cracked due to changes in air pressure inside the battery cell 20 or external impact, and the priority detonation area 2142 can be cracked more promptly when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the depressurization 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 detonation area 2142 is greater, and the priority detonation area 2142 is less likely to crack prematurely due to pressure changes inside the battery cell 20 or external impacts, which is beneficial to reduce the risk of the priority detonation area 2142 being damaged prematurely. When L2≤30mm, when the battery cell 20 releases internal pressure, the priority detonation area 2142 undergoes a large deformation under the action of gas, so that the priority detonation area 2142 can crack more timely, which is beneficial to improve the timeliness of pressure relief of the battery cell 20. Therefore, when 10mm≤L2≤30mm, the priority detonation area 2142 is not easy to crack due to pressure changes inside the battery cell 20 or external impacts, and it is easy for the priority detonation area 2142 to crack in time, which is beneficial to improve the timeliness of pressure relief of the battery cell 20.

[0212] Please refer to Fig. 9 , Fig. 9A bottom view of the housing 21 of the battery cell 20 provided for 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 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 ​​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 which are arranged opposite to each other, wherein the first outer surface 2111 faces away from the interior of the housing 21, and the first inner surface 2112 faces the interior of the housing 21. The first groove 2141 can be arranged on the first outer surface 2111 or on the first inner surface 2112. Figure 5 and Figure 6 In the embodiment shown in the figure, the first groove 2141 is arranged on the first outer surface 2111.

[0214] The pressure relief component 214 forms a first weak portion 2145 in the area where the first groove 2141 is provided, which can also be understood as the first weak portion 2145 being formed on the bottom wall of the first groove 2141. Figure 5 and Figure 6 In the embodiment shown in the figure, along the thickness direction of the first wall portion 211, the first weak portion 2145 is a portion of the pressure relief component 214 located between the bottom surface of the first groove 2141 farthest from the first outer surface 2111 and the first inner surface 2112.

[0215] The first groove 2141 can be formed by various methods, such as stamping, cold heading, etc. Stamping or cold heading the first groove 2141 will cause the groove wall of the first groove 2141 to undergo cold work hardening (the grain arrangement changes, resulting in lattice distortion, which reduces the plasticity of the metal and increases the hardness of the material), and its ability to resist external impact is enhanced, and it is not easily damaged by external impact. In this way, the risk of leakage of the pressure relief component 214 is reduced.

[0216] 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. Fig. 9 In the embodiment, one end of the first slot segment 2141a is connected to one end of the second slot segment 2141b, and both the first slot segment 2141a and the second slot segment 2141b are straight slot segments, so that the first slot segment 2141a and the second slot segment 2141b form an "L"-shaped first groove 2141. Of course, in other embodiments, one end of the first slot segment 2141a may also be connected to the middle position of the second slot segment 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 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. The first weak portion 2145 within the circular range with the first intersection 21421 as the center and a radius of 5 mm is the above-mentioned priority detonation area 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] Please refer again Figure 5 and Figure 6The first groove 2141 includes a third groove section 2141c. The first groove section 2141a and the third groove section 2141c are arranged opposite to each other. The second groove section 2141b connects the first groove section 2141a and the third groove section 2141c. The center line of the groove bottom surface of the second groove section 2141b and the center line of the groove bottom surface of the third groove section 2141c intersect at the second intersection 21422. The extension direction of the center line of the groove bottom surface of the third groove section 2141c is parallel to the extension direction of the third groove section 2141c. The area of ​​the first weak portion 2145 within the range of radius R with the second intersection 21422 as the center is the priority detonation area 2142.

[0223] The first slot section 2141a and the third slot section 2141c are arranged at intervals and at least partially opposite 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 respectively connected to the first slot section 2141a and the third slot section 2141c. 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 Figure 5 and Figure 6 In the embodiment shown in the figure, the connection position of 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 of 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, so that 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 center line of the bottom surface of the second groove section 2141b and the center line of the bottom surface of the third groove section 2141c. The first weak portion 2145 within the circular range with the second intersection 21422 as the center and a radius of 5 mm is the above-mentioned priority detonation area 2142.

[0227] Please refer to Figure 5 ,exist Figure 5In the illustrated embodiment, the first weak portion 2145 includes two priority detonation areas 2142. The area of ​​the first weak portion 2145 within a circular range with the first intersection 21421 as the center and a radius of 5 mm is one priority detonation area 2142, and the area of ​​the first weak portion 2145 within a circular range with the second intersection 21422 as the center and a radius of 5 mm is another priority detonation area 2142. The above two priority detonation areas 2142 are arranged at intervals, that is, at Figure 5 In the illustrated embodiment, the distance between the first intersection point 21421 and the second intersection point 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, and the area of ​​the first weak portion 2145 within the range of 5 mm as the 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 are cracked first, and then the first groove section 2141a, the second groove section 2141b and the third groove section 2141c are gradually cracked along their extension direction, thereby realizing rapid depressurization of the battery cell 20.

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

[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 multiple 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. Figure 5 and Figure 6 ,exist Figure 5 and Figure 6 In the embodiment shown, 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. Figure 7 and Figure 8 ,exist Figure 7 and Figure 8 In the illustrated embodiment, 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≥10mm, the minimum radial dimension of the first outer surface 2111 is relatively large, and the stiffness of the outer edge of the first wall portion 211 close to the first outer surface 2111 and the stiffness of the first wall portion 211 close to the center point of the first outer surface 2111 are quite different. In this case, arranging the first weak portion 2145 inside the first edge 2143 has a better effect. 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] Please refer to Figure 5 and Figure 6 In some embodiments, the thickness of the area of ​​the pressure relief component 214 where the first weak portion 2145 is not provided is D1, satisfying: 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 by 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≥0.1mm, the thickness of the area where the first weak portion 2145 is not provided in the pressure relief component 214 is relatively large, and the minimum thickness of the first weak portion 2145 provided in the pressure relief component 214 can also be relatively large. In this way, when the battery cell 20 is in normal use, the first weak portion 2145 is not easy to be cracked in advance due to the pressure change inside the battery cell 20 or the external impact, which is conducive to reducing the risk of the first weak portion 2145 being damaged in advance and improving the life of the battery cell 20. When D1≤10mm, the thickness of the area where the first weak portion 2145 is not provided in the pressure relief component 214 is not too large, and it is not necessary to remove too much material when processing the first weak portion 2145, which is conducive to reducing the waste of materials and the difficulty of processing. Therefore, when 0.1mm≤D1≤10mm, the thickness of the processed first weak portion 2145 can be made more appropriate, reducing the risk of the first weak portion 2145 being damaged in advance, which is conducive to improving the life of the battery cell 20. In addition, it is conducive to reducing the waste of materials and the difficulty of processing.

[0236] Please refer to Figure 7 and Figure 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 a wall portion adjacent to the first wall portion 211. Figure 7 and Figure 8 In the embodiment shown, the second wall portion 212 is a peripheral 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 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 some other embodiments, the second wall portion 212 and the first wall portion 211 have rounded transitions.

[0240] Please refer again Figure 3 , Figure 4 and Figure 5 The housing 21 includes a shell 215 and an end cover 216. An opening 2151 is formed at at least one end of the shell 215. The end cover 216 corresponds to the opening 2151 one by one, and the end cover 216 closes the opening 2151. 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 a bottom wall, that is, the shell 215 is manufactured by an integral molding process, such as an integral molding process such as stamping, casting or extrusion molding, that is, the side wall and the 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. Figure 5 In the embodiment, the first wall portion 211 is a bottom wall of the housing 215 disposed opposite to the end cover 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 , and the fluid medium sprayed by the pressure relief component 214 is not likely to act on other electrical connection structures on the end cover 216 , which is beneficial to reducing the risk of short circuit of the battery cell 20 .

[0244] In some embodiments, the thickness of the area of ​​the pressure relief component 214 where the first weak portion 2145 is not provided is smaller than the thickness of the end cover 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 releases pressure.

[0246] In other embodiments, the battery cell 20 may also be 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, and the accommodating cavity 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. The shell 215 has a housing cavity formed inside, which is used to accommodate the electrode assembly 22. The shell 215 has openings 2151 formed at both ends of the first wall portion 211 in the thickness direction, and the two openings 2151 are connected to the housing 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] The pressure relief component 214 and the first wall portion 211 are integrally formed without additional welding or bonding steps, which is conducive to reducing the risk of leakage of the pressure relief component 214. In addition, during production, it is easy to make the detonation pressure of the processed multiple battery cells 20 more consistent.

[0252] In some other embodiments, the pressure relief component 214 is separately provided 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 pressure relief component 214 is separately provided 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” means that during manufacturing, a pressure relief hole is opened on the first wall portion 211, and the pressure relief component 214 and the first wall portion 211 are provided separately and finally connected together. For example, the pressure relief component 214 can be welded to the first wall portion 211. The pressure relief component 214 can be a burst-proof disk installed on the first wall portion 211.

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

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

[0256] It is understandable that in the embodiment where the pressure relief component 214 and the first wall portion 211 are integrally formed, the material of the first wall portion 211 includes steel. The material of the first wall portion 211 includes steel. If the first wall portion 211 is the end cover 216 of the housing 21, the material of the end cover 216 is steel; if the first wall portion 211 is a wall in the housing 215, the material of the housing 215 is 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 has low cost and is easy to manufacture.

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

[0263] It is understandable that in the embodiment where the pressure relief component 214 and the first wall portion 211 are integrally formed, the material of the first wall portion 211 includes aluminum alloy. If the first wall portion 211 is an end cover 216, the end cover 216 can be made of aluminum alloy; if the first wall portion 211 is a wall portion in the housing 215, the housing 215 can be made of aluminum alloy.

[0264] Aluminum alloy has the characteristics of light weight and good ductility, and it is easier to process 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 single elements ≤ 0.03%.

[0266] This aluminum alloy belongs to the third series aluminum, and has lower hardness and better forming ability, which 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 single element components ≤ 0.05%, and the total composition of other elements ≤ 0.15%.

[0268] This aluminum alloy belongs to the fifth series aluminum, and 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, and the battery 100 includes the above-mentioned battery cell 20.

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

[0270] According to some embodiments of this application, please refer to Figure 3 to Figure 9 .

[0271] The embodiment of the present application provides a battery cell 20, which includes a housing 21 and a pressure relief component 214. The housing 21 has a first wall portion 211, the first wall portion 211 has a first outer surface 2111 facing away from the interior of the housing 21, and the pressure relief component 214 is disposed on the first wall portion 211. The pressure relief component 214 includes a first weak portion 2145, and the pressure relief component 214 is configured to be able to be split along at least a portion of the first weak portion 2145 when the battery cell 20 is depressurized. The minimum radial dimension of the first outer surface 2111 is A, and 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, 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 outer edge of the first outer surface 2111 is offset by 0.05A toward the center point of the first outer surface 2111 to form a first edge 2143, and the first edge 2143 defines a first area 2144 on the first wall portion 211. The first area 2144 is close to the center of the wall portion. The first area 2144 is an area with relatively small rigidity on the wall portion, and its ability to resist deformation is relatively weak. When the battery cell 20 releases the internal pressure, the first area 2144 undergoes a large deformation under the action of the gas, and the first weak portion 2145 arranged in the first area 2144 is easily deformed and damaged. Therefore, under the same detonation pressure, the thickness of the first weak portion 2145 arranged in the first area 2144 can be larger. In this way, when the battery cell 20 is used normally, the first weak portion 2145 is not easy to cause the first weak portion 2145 to crack prematurely due to the pressure change inside the battery cell 20 or the external impact, which is conducive to reducing the risk of premature damage to the first weak portion 2145 and improving the life 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 a cylindrical structure, and the housing 21 includes a second wall portion 212, and the second wall portion 212 is arranged around the first wall portion 211. 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. The housing 21 is a cylindrical structure, and the second wall portion 212 is arranged around the first wall portion 211, then the second wall portion 212 is the peripheral wall of the housing 21, and the first wall portion 211 is connected to one end of the second wall portion 212. At this time, 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, and the first edge 2143 is a circle with a diameter of 0.9A.

[0273] In other embodiments, the housing 21 is a prism structure, and the first outer surface 2111 is 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 to each other along the width direction of the first wall portion 211, and the two first short sides 21112 are arranged opposite to each other along the length direction of the first wall portion 211. 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 is a rectangular structure, the long side of the first edge 2143 is 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 side of the first edge 2143 is 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 priority detonation area 2142, and the priority detonation area 2142 is cracked earlier than other areas of the first weak portion 2145 when the battery cell 20 is depressurized. The minimum distance between the projection of the priority detonation area 2142 on the first outer surface 2111 along the thickness direction of the first wall portion 211 and the center point of the first outer surface 2111 is L2, and the minimum thickness of the priority detonation area 2142 is D, which satisfies: 5mm≤L2≤40mm, 0.05mm≤D≤0.6mm. The first weak portion 2145 has a priority detonation area 2142, and when the battery cell 20 is depressurized, the priority detonation area 2142 is cracked first, and then other areas of the first weak portion 2145 are gradually cracked along the extension direction of the first weak portion 2145. When D≥0.05mm, the minimum thickness of the priority detonation area 2142 is relatively large, so that the priority detonation area 2142 is not easy to crack prematurely due to changes in the air pressure inside the battery cell 20 or external impact, which is beneficial to improving the life of the battery cell 20. When D≤0.6mm, the minimum thickness of the priority detonation area 2142 is not too large, so that the priority detonation area 2142 can be cracked in time when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20. Therefore, when 0.05mm≤D≤0.6mm, the priority detonation area 2142 is not easy to crack due to changes in the air pressure inside the battery cell 20 or external impact, and it is easy for the priority detonation area 2142 to crack in time, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20. When L2≥5mm, the minimum distance between the projection of the priority detonation area 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 large, and the rigidity of the location of the priority detonation area 2142 is large. When the battery cell 20 is in normal use, the priority detonation area 2142 is not easy to be cracked in advance due to the pressure change inside the battery cell 20 or the external impact, which is conducive to reducing the risk of the priority detonation area 2142 being damaged in advance. When L2≤40mm, the minimum distance between the projection of the priority detonation area 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 not too large. When the battery cell 20 releases the internal pressure, the priority detonation area 2142 undergoes a large deformation under the action of gas, so that the priority detonation area 2142 can be cracked in time, which is conducive to improving the timeliness of the pressure release of the battery cell 20. Therefore, when 5mm≤L2≤40mm, the priority detonation area 2142 is not easily cracked due to the change of air pressure inside the battery cell 20 or external impact, and it is easy for the priority detonation area 2142 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, 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 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, and 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 ​​the first weak portion 2145 within the range of radius R with the first intersection 21421 as the center is the priority detonation area 2142, and A>R=5mm. 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 to each other. The second groove section 2141b connects the first groove section 2141a and the third groove section 2141c. The center line of the groove bottom surface of the second groove section 2141b and the center line of the groove bottom surface of the third groove section 2141c intersect at the second intersection 21422. The extension direction of the center line of the groove bottom surface of the third groove section 2141c is parallel to the extension direction of the third groove section 2141c. The area of ​​the first weak portion 2145 within the range of radius R with the second intersection 21422 as the center is the priority detonation area 2142. The stress at the intersection of the second groove section 2141b and the third groove section 2141c is more concentrated, and the area of ​​the first weak portion 2145 within the range of 5 mm as the 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 are cracked first, and then the first groove section 2141a, the second groove section 2141b and the third groove section 2141c are gradually cracked along their extension direction, thereby realizing rapid depressurization of the battery cell 20.

[0277] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, characterized in that: include: a housing having a first wall portion, the first wall portion having a first outer surface facing away from the interior of the housing; The first wall portion includes a first weak portion, and the first wall portion is configured to be able to be broken 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, 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 from 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, a projection of the first weak portion on the first outer surface is located inside the first edge.

2. The battery cell according to claim 1, characterized in that: The shell is a cylindrical structure, and 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.

3. The battery cell according to claim 1, characterized in that: 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 relatively arranged along the width direction of the first wall portion, the two first short sides are relatively arranged 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.

4. The battery cell according to claim 1, characterized in that: 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, which satisfies: 5mm≤L2≤40mm, 0.05mm≤D≤0.6mm.

5. The battery cell according to claim 4, characterized in that: 0.1mm≤D≤0.5mm.

6. The battery cell according to claim 4, characterized in that: 10mm≤L2≤30mm.

7. The battery cell according to claim 4, characterized in that: The first wall portion is provided with a first groove, and the first wall portion forms the first weak portion 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 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 area, and A>R=5mm.

8. The battery cell according to claim 7, characterized in that: 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 point, 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 point as the center is the priority detonation area.

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

10. The battery cell according to any one of claims 1 to 8, characterized in that: The thickness of the first wall portion in an area where the first weak portion is not provided is D1, which satisfies: 0.1 mm≤D1≤10 mm.

11. The battery cell according to any one of claims 1 to 8, characterized in that: 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 to 8, characterized in that: The housing comprises: A shell having an opening formed at at least one end; An end cover, corresponding to each of the openings, and closing the openings; Wherein, at least one wall in the shell is the first wall portion.

13. The battery cell according to claim 12, characterized in that: The thickness of the first wall portion in a region where the first weak portion is not provided is smaller than the thickness of the end cover.

14. A battery, characterized in that: Comprising a battery cell according to any one of claims 1-13.

15. An electrical equipment, characterized in that: Comprising a battery cell according to any one of claims 1-13.

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