Pressure relief devices, battery cells, batteries and electrical equipment

Abstract

The embodiments of the present application provide a pressure relief device, a battery cell, a battery and an electrical device, which belong to the field of battery technology. The embodiments of the present application provide a pressure relief device for a battery cell, and the pressure relief device includes a pressure relief body and two pressure relief grooves. The pressure relief body has a first surface and a second surface arranged relative to each other along its thickness direction. The two pressure relief grooves are arranged relative to each other along the thickness direction, and are respectively arranged on the first surface and the second surface. A weak portion is formed between the two pressure relief grooves, and the weak portion is configured to crack when the pressure or temperature inside the battery cell reaches a threshold value to release the pressure inside the battery cell. The first surface and the second surface of the pressure relief body are both provided with pressure relief grooves, which can obtain a lower residual thickness, reduce the thickness of the weak portion, make the weak portion easier to crack, reduce the detonation pressure of the pressure relief device, and enable the pressure relief body to relieve pressure in time, reduce the risk of fire, explosion, etc. in the battery cell, and effectively improve the safety of the battery cell.

Description

Technical Field

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

[0002] With the development of new energy technology, batteries are used more and more widely, for example, in mobile phones, laptops, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and power tools.

[0003] In the development of battery technology, in addition to improving the performance of battery cells, safety issues are also an issue that needs to be considered. Therefore, how to improve the safety of battery cells is an urgent problem to be solved in battery technology. Summary of the Invention

[0004] The embodiments of the present application provide a pressure relief device, a battery cell, a battery, and an electrical device, which can effectively improve the safety of the battery cell.

[0005] In a first aspect, an embodiment of the present application provides a pressure relief device for a battery cell, comprising: a pressure relief body having a first surface and a second surface arranged opposite to each other along its thickness direction; two pressure relief grooves arranged opposite to each other along the thickness direction and respectively arranged on the first surface and the second surface, a weak portion being formed between the two pressure relief grooves, and the weak portion being configured to rupture when the pressure or temperature inside the battery cell reaches a threshold value to release the pressure inside the battery cell.

[0006] In the above technical solution, pressure relief grooves are provided on both the first and second surfaces of the pressure relief body, which can obtain a lower residual thickness, reduce the thickness of the weak part, make the weak part easier to crack, reduce the detonation pressure of the pressure relief device, and enable the pressure relief body to relieve pressure in time, thereby reducing the risk of fire and explosion of the battery cell, and effectively improving the safety of the battery cell.

[0007] In some embodiments, the distance between the first surface and the second surface is a first distance, and the ratio of the minimum thickness of the weak portion to the first distance is 0.12-0.5. If the ratio of the minimum thickness of the weak portion to the first distance is too small, the minimum thickness of the weak portion is too small, which may cause the weak portion to crack during the molding process. Even if the weak portion does not crack, the strength of the pressure relief body is poor, making it prone to cracking and releasing pressure in a vibrating environment or before the pressure or temperature inside the battery cell reaches a threshold, thus shortening the battery cell's service life. If the ratio of the minimum thickness of the weak portion to the first distance is too large, the minimum thickness of the weak portion is too large, making it prone to not cracking and releasing pressure even when the pressure or temperature inside the battery cell reaches a threshold. This delayed pressure relief can lead to accidents such as battery cell fires and explosions. Therefore, setting the ratio of the minimum thickness of the weak portion to the first distance to 0.12-0.5 ensures that the pressure relief device can promptly release pressure when the internal pressure of the battery cell reaches the threshold, while also ensuring that the pressure relief device has sufficient strength before pressure relief.

[0008] In some embodiments, the pressure relief groove extends circumferentially along the pressure relief body and defines a pressure relief portion. The pressure relief portion is configured to open with the weakened portion as the boundary to release pressure from the battery cell when the pressure or temperature inside the battery cell reaches a threshold. This structure effectively increases the pressure relief area of the pressure relief device, thereby increasing the pressure relief rate of the pressure relief device, reducing the risk of fire and explosion in the battery cell, and improving the safety of the battery cell.

[0009] In some embodiments, along the circumference of the pressure relief body, there is a distance between the two ends of the pressure relief groove. In this way, when the weak portion ruptures to release pressure, the area between the two ends of the pressure relief groove does not rupture, allowing the pressure relief portion to open in an outwardly flipped manner, preventing the pressure relief portion from falling off and flying out as a whole during pressure relief.

[0010] In some embodiments, the pressure relief groove is in the shape of an arc extending along the circumference of the pressure relief body. The pressure relief groove of this structure has a regular shape and is easy to process and shape, so that the pressure relief part can open regularly when the pressure is released.

[0011] In some embodiments, the pressure relief body further comprises an outer surface and an inner surface, the outer surface being disposed opposite the inner surface along the thickness direction, and the pressure relief portion being configured to open from the inner surface toward the outer surface when the pressure or temperature inside the battery cell reaches a threshold value. The pressure relief body is provided with a recessed portion, which is recessed from the outer surface along the thickness direction toward the inner surface, with the bottom surface of the recess forming the first surface. The recessed portion provides a clearance space for the pressure relief portion when it opens outward, ensuring normal opening of the pressure relief portion even if there is an obstruction on the outer surface of the pressure relief body, thereby reducing the risk of the pressure relief portion being unable to open due to the obstruction interfering with the outer surface.

[0012] In some embodiments, a convex portion is formed on the inner surface of the pressure relief body at a position corresponding to the concave portion. Along the thickness direction, the surface of the convex portion facing away from the inner surface forms the second surface. The provision of the convex portion can improve the strength of the pressure relief body in the region where the concave portion is provided, thereby avoiding the problem of localized strength deficiency caused by the provision of the concave portion on the pressure relief body.

[0013] In some embodiments, the pressure relief groove includes: two groove side surfaces, disposed facing each other along the width of the groove; and a groove bottom surface connected to the two groove side surfaces; wherein the area between the two groove bottom surfaces of the pressure relief grooves forms the weak portion. This structure of the pressure relief groove is easy to process and can be formed by stamping.

[0014] In some embodiments, the bottom surface of the groove is an arc-shaped surface that is concave along the depth direction of the pressure relief groove. This structure allows the thickness of the weak portion to gradually decrease from both sides to the middle position, allowing the weak portion to rupture from the weakest position in the middle during pressure relief, making the weak portion easier to rupture and ensuring that the weak portion can rupture and release pressure in time when the pressure or temperature inside the battery cell reaches a threshold value.

[0015] In some embodiments, the groove bottom surface includes a bottom plane and an arc-shaped chamfered surface, with the bottom plane connected to each groove side surface via one of the arc-shaped chamfered surfaces. This structure makes the middle area of the weak portion (the area corresponding to the weak portion and the bottom plane) the weakest, making the weak portion more likely to rupture, ensuring that the weak portion can rupture and release pressure in a timely manner when the pressure or temperature inside the battery cell reaches a threshold.

[0016] In some embodiments, the distance between the two side surfaces of the pressure relief groove gradually decreases along the depth direction of the pressure relief groove. This structure can effectively reduce the width of the weak part, making the weak part more likely to break when the pressure or temperature inside the battery cell reaches a threshold.

[0017] In some embodiments, an anti-oxidation layer is formed on the surface of the pressure relief body, and the anti-oxidation layer extends along the wall surface of the pressure relief groove in the area where the pressure relief groove is located. The anti-oxidation layer protects the pressure relief body from oxidation. Of course, since the anti-oxidation layer extends along the wall surface of the pressure relief groove in the area where the pressure relief groove is located, the anti-oxidation layer also protects the area where the pressure relief groove is located, reducing the risk of oxidation of the pressure relief body in the area where the pressure relief groove is located, which may lead to weakening of the weak portion.

[0018] In some embodiments, the thickness of the anti-oxidation layer in the pressure relief groove area is thinner than the thickness of the anti-oxidation layer in other areas. This reduces the impact of the anti-oxidation layer in the pressure relief groove area on the weak portion, ensuring that the weak portion can rupture and release pressure in a timely manner when the pressure or temperature inside the battery cell reaches a threshold.

[0019] In a second aspect, an embodiment of the present application provides a battery cell, comprising: an electrode assembly; and a housing for accommodating the electrode assembly, wherein the housing comprises the pressure relief device provided in any one of the embodiments of the first aspect.

[0020] In some embodiments, the housing further includes a shell, the shell being used to accommodate the electrode assembly, the shell having an opening, and the pressure relief body being used to cover the opening.

[0021] In a third aspect, an embodiment of the present application provides a battery, comprising: a battery cell provided in any one embodiment of the second aspect above; and a box for accommodating the battery cell.

[0022] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising a battery provided by any embodiment of the third aspect.

[0023] In a fifth aspect, an embodiment of the present application provides a method for manufacturing a pressure relief device, the manufacturing method comprising: providing a pressure relief body, the pressure relief body having a first surface and a second surface arranged opposite to each other along its thickness direction, the first surface and the second surface being arranged opposite to each other along the thickness direction of the pressure relief body; processing pressure relief grooves on the first surface and the second surface, so that the pressure relief grooves on the first surface and the pressure relief grooves on the second surface are arranged opposite to each other along the thickness direction, and a weak portion is formed between the pressure relief grooves on the first surface and the pressure relief grooves on the second surface, and the weak portion is configured to rupture when the pressure or temperature inside the battery cell reaches a threshold value to release the pressure inside the battery cell.

[0024] In a sixth aspect, an embodiment of the present application further provides a manufacturing device for a pressure relief device, the manufacturing device comprising: a providing device for providing a pressure relief body, the pressure relief body having a first surface and a second surface arranged relative to each other along its thickness direction, the first surface and the second surface being arranged relative to each other along the thickness direction of the pressure relief body; a processing device for processing pressure relief grooves on the first surface and the second surface, so that the pressure relief grooves on the first surface and the pressure relief grooves on the second surface are arranged relative to each other along the thickness direction, and a weak portion is formed between the pressure relief grooves on the first surface and the pressure relief grooves on the second surface, and the weak portion is configured to rupture when the pressure or temperature inside the battery cell reaches a threshold value to release the pressure inside the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0027] Figure 2 An exploded view of a battery provided in accordance with some embodiments of the present application;

[0028] Figure 3 An exploded view of a battery cell provided in some embodiments of the present application;

[0029] Figure 4 for Figure 3 The structural diagram of the pressure relief device shown;

[0030] Figure 5 for Figure 4 A partial view of the pressure relief device is shown;

[0031] Figure 6 for Figure 4 AA sectional view of the pressure relief device shown;

[0032] Figure 7 A partial enlarged view of a pressure relief device provided in some embodiments of the present application;

[0033] Figure 8 A partial enlarged view of a pressure relief device provided in some other embodiments of the present application;

[0034] Figure 9 A partial cross-sectional view of a pressure relief device provided in some other embodiments of the present application;

[0035] Figure 10 A flow chart of a method for manufacturing a pressure relief device provided in some embodiments of the present application;

[0036] Figure 11 A schematic block diagram of a manufacturing apparatus for a pressure relief device provided in some embodiments of the present application.

[0037] Icons: 10-housing; 11-first part; 12-second part; 20-battery cell; 21-electrode assembly; 22-housing; 23-end cover; 24-pressure relief device; 241-pressure relief body; 2411-first surface; 2412-second surface; 2413-weak part; 2414-pressure relief part; 2415-outer surface; 2415a-recess; 2415b-welding groove; 2416-inner surface; 2416a-convex part; 2416 b-protrusion; 2417-anti-oxidation layer; 242-pressure relief groove; 2421-groove side; 2422-groove bottom; 2422a-bottom plane; 2422b-arc chamfered surface; 25-electrode terminal; 26-current collecting component; 100-battery; 200-controller; 300-motor; 1000-vehicle; 2000-manufacturing equipment; 2100-providing device; 2200-processing device; X-width direction; Y-circumferential direction; Z-thickness direction. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0039] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0040] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0041] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0042] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0043] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0044] The term "plurality" used in this application refers to two or more (including two).

[0045] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0046] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0047] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive electrode collector. The uncoated positive electrode collector protrudes from the coated positive electrode collector, and the uncoated positive electrode collector serves as the positive electrode tab. For lithium-ion batteries, for example, the positive electrode current collector can be made of aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative electrode collector. The uncoated negative electrode collector protrudes from the coated negative electrode collector, and the uncoated negative electrode collector serves as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, among others. To ensure that high currents can pass without fusing, multiple positive electrode tabs are stacked together, and multiple negative electrode tabs are stacked together. The separator can be made of materials such as PP (polypropylene) or PE (polyethylene). Furthermore, the electrode assembly can be a wound or laminated structure, but the embodiments of the present application are not limited thereto.

[0048] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery safety must also be considered.

[0049] In order to ensure the safety of the battery cell, a pressure relief device is generally provided in the battery cell. When the internal pressure or temperature of the battery cell reaches a threshold, the pressure inside the battery cell is released through the pressure relief device to ensure the safety of the battery cell.

[0050] The inventors noted that even if a pressure relief device is installed in a battery cell, safety issues such as battery cell fire and explosion may still occur. Further research by the inventors revealed that in related art, pressure relief devices generally include a pressure relief groove on the pressure relief body. During pressure relief, the pressure relief body splits at the location where the groove is installed to achieve the purpose of pressure relief. In-depth research by the inventors revealed that the pressure relief groove is generally installed on a single side of the pressure relief body. To meet design requirements and ensure that the pressure relief body promptly relieves pressure when the pressure or temperature inside the battery cell reaches a threshold, the groove needs to be machined to a certain depth so that the residual thickness of the pressure relief body after the groove is installed is not too thick. However, due to limitations in the processing technology and the pressure relief body material, it is difficult to achieve the residual thickness required by the design when the pressure relief body is thick and / or the material of the pressure relief body is hard. This results in a higher detonation pressure of the pressure relief device, resulting in the pressure relief device being unable to relieve pressure when it should, and unable to promptly release the pressure inside the battery cell, thus causing safety issues such as battery cell fire and explosion.

[0051] In view of this, an embodiment of the present application provides a pressure relief device, in which pressure relief grooves are arranged on the first surface and the second surface opposite to each other of the pressure relief body, and a weak portion is formed between the pressure relief groove on the first surface and the pressure relief groove on the second surface. The weak portion is configured to crack when the pressure or temperature inside the battery cell reaches a threshold value to release the pressure inside the battery cell.

[0052] In such a pressure relief device, pressure relief grooves are provided on both the first and second surfaces of the pressure relief body, which can obtain a lower residual thickness, reduce the thickness of the weak part, make the weak part easier to crack, reduce the detonation pressure of the pressure relief device, and enable the pressure relief body to relieve pressure in time, thereby reducing the risk of fire and explosion of the battery cell, and effectively improving the safety of the battery cell.

[0053] In addition, since pressure relief grooves are provided on both the first and second surfaces of the pressure relief body, the difficulty of forming can be effectively reduced, the processing accuracy can be ensured, and the thickness of the weak part can be precisely controlled so that the thickness of the weak part meets the detonation requirements.

[0054] The pressure relief device described in the embodiments of the present application is applicable to battery cells, batteries, and electrical equipment using batteries.

[0055] Electrical equipment can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and electric tools, etc. Vehicles can be fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.

[0056] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0057] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application. A battery 100 is disposed inside the vehicle 1000. The battery 100 can be disposed at the bottom, head, or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000.

[0058] The vehicle 1000 may further include a controller 200 and a motor 300 . The controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0059] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0060] Please refer to Figure 2 , Figure 2 This is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a case 10 and a battery cell 20 . The case 10 is used to accommodate the battery cell 20 .

[0061] The housing 10 is a component that houses the battery cells 20, providing a storage space for the battery cells 20. The housing 10 can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap to define a storage space for the battery cells 20. The first portion 11 and the second portion 12 can have various shapes, such as a rectangular parallelepiped or a cylinder. The first portion 11 can be a hollow structure with one side open, and the second portion 12 can also be a hollow structure with one side open. The open side of the second portion 12 overlaps the open side of the first portion 11, forming the housing 10 with a storage space. Alternatively, the first portion 11 can be a hollow structure with one side open, and the second portion 12 can be a plate-like structure. The second portion 12 overlaps the open side of the first portion 11, forming the housing 10 with a storage space. The first portion 11 and the second portion 12 can be sealed by a sealing element, such as a sealing ring, sealant, etc.

[0062] In the battery 100, there can be one or more battery cells 20. If there are multiple battery cells 20, the multiple battery cells 20 can be connected in series, parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. Multiple battery cells 20 can be connected in series, parallel, or in a hybrid connection to form a battery module, which is then connected in series, parallel, or in a hybrid connection to form a whole and housed within the housing 10. Alternatively, all battery cells 20 can be directly connected in series, parallel, or in a hybrid connection, and then the whole battery module can be housed within the housing 10.

[0063] In some embodiments, the battery 100 may further include a busbar component, through which the multiple battery cells 20 can be electrically connected to each other, thereby enabling series connection, parallel connection, or hybrid connection of the multiple battery cells 20. The busbar component may be a metal conductor, such as copper, iron, aluminum, stainless steel, or aluminum alloy.

[0064] Please refer to Figure 3 , Figure 3 This is an exploded view of a battery cell 20 provided in some embodiments of the present application. The battery cell 20 may include a housing and an electrode assembly 21. The housing is used to accommodate the electrode assembly 21. The housing may include a shell 22, an end cap 23, and a pressure relief device 24.

[0065] The housing 22 is a component for accommodating the electrode assembly 21. The housing 22 can be a hollow structure with an opening at one end, or a hollow structure with openings at two opposing ends. The housing 22 can have various shapes, such as a cylinder or a rectangular parallelepiped. The housing 22 can be made of various materials, such as copper, iron, aluminum, steel, and aluminum alloys.

[0066] The electrode assembly 21 is the component in the battery cell 20 where the electrochemical reaction occurs. The electrode assembly 21 may include a positive electrode sheet, a negative electrode sheet, and a separator. The electrode assembly 21 may be a wound structure formed by winding the positive electrode sheet, separator, and negative electrode sheet, or a laminated structure formed by stacking the positive electrode sheet, separator, and negative electrode sheet. The electrode assembly 21 has a positive electrode tab and a negative electrode tab. The positive electrode tab may be the portion of the positive electrode sheet not coated with the positive electrode active material layer, and the negative electrode tab may be the portion of the negative electrode sheet not coated with the negative electrode active material layer.

[0067] The end cap 23 is a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 20 from the external environment. The end cap 23 covers the opening of the shell 22, and the end cap 23 and the shell 22 together define a sealed space for accommodating the electrode assembly 21, electrolyte, and other components. The shape of the end cap 23 can be adapted to the shape of the shell 22. For example, if the shell 22 is a rectangular parallelepiped structure, the end cap 23 is a rectangular plate structure that is adapted to the shell 22. For another example, if the shell 22 is a cylindrical structure, the end cap 23 is a circular plate structure that is adapted to the shell 22. The material of the end cap 23 can also be various, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0068] In the battery cell 20, there can be one or two end caps 23. If the housing 22 is a hollow structure with an opening at one end, one end cap 23 is provided. If the housing 22 is a hollow structure with openings at both ends, two end caps 23 are provided, one covering each opening of the housing 22.

[0069] The battery cell may be provided with an electrode terminal 25, which may be provided on the end cap 23 or on the housing 22. The electrode terminal 25 is used to electrically connect to the electrode assembly 21 to output the electrical energy of the battery cell 20. In an embodiment where there are two end caps 23 in the battery cell 20, both end caps 23 may be provided with an electrode terminal 25. The electrode terminal 25 on one end cap 23 may be electrically connected to the positive electrode tab of the electrode assembly 21, and the electrode terminal 25 on the other end cap 23 may be electrically connected to the negative electrode tab of the electrode assembly 21. Figure 3 As shown, in an embodiment where there is only one end cap 23 in the battery cell 20, the electrode terminal 25 may be provided only on the shell, and the electrode terminal 25 may be electrically connected to the positive electrode tab of the electrode assembly 21, and the end cap 23 may be electrically connected to the negative electrode tab of the electrode assembly 21.

[0070] A current collecting member 26 may also be provided in the battery cell 20 to electrically connect the electrode terminal 25 to the tab or the end cap 23 to the tab. For example, if there is only one end cap 23 in the battery cell 20, the electrode terminal 25 on the housing 22 is connected to the positive tab of the electrode assembly 21 via one current collecting member 26, and the end cap 23 is connected to the negative tab of the electrode assembly 21 via another current collecting member 26.

[0071] The pressure relief device 24 is a component for releasing the pressure inside the battery cell 20. When the pressure or temperature inside the battery cell 20 reaches a threshold, the pressure inside the battery cell 20 is released through the pressure relief device 24. The specific structure of the pressure relief device 24 is described in detail below with reference to the accompanying drawings.

[0072] Please refer to Figure 4 and Figure 5 , Figure 4 for Figure 3 The structural diagram of the pressure relief device 24 is shown in FIG. Figure 5 for Figure 4 The partial view of the pressure relief device 24 shown in the figure, the embodiment of the present application provides a pressure relief device 24 for a battery cell 20, the pressure relief device 24 includes a pressure relief body 241 and two pressure relief grooves 242. The pressure relief body 241 has a first surface 2411 and a second surface 2412 arranged opposite to each other along its thickness direction Z. The two pressure relief grooves 242 are arranged opposite to each other along the thickness direction Z of the pressure relief device 24, and are respectively arranged on the first surface 2411 and the second surface 2412. A weak portion 2413 is formed between the two pressure relief grooves 242, and the weak portion 2413 is configured to rupture when the pressure or temperature inside the battery cell 20 reaches a threshold value to release the pressure inside the battery cell 20.

[0073] The pressure relief body 241 can be the end cover 23 itself, or it can be the shell 22 itself. The pressure relief body 241 can be an independent component installed on the end cover 23, or it can be an independent component installed on the shell 22, such as an explosion-proof valve, an explosion-proof disk, etc. The shape of the pressure relief body 241 can be various. Taking the pressure relief body 241 as the end cover 23 as an example, the pressure relief body 241 can be rectangular, circular, etc. Exemplarily, the pressure relief body 241 is made of a harder material, and the tensile strength of the pressure relief body 241 is 108 MPa to 384 MPa for steel. The pressure relief body 241 can be made of metal, such as copper, iron, aluminum, steel, and aluminum alloy.

[0074] In the battery cell 20, the first surface 2411 of the pressure relief body 241 can be the outermost surface of the pressure relief body 241, or a stepped surface that is spaced apart from the outermost surface of the pressure relief body 241 and faces the outside of the battery cell 20. The second surface 2412 of the pressure relief body 241 can be the innermost surface of the pressure relief body 241, or a stepped surface that is spaced apart from the innermost surface of the pressure relief body 241 and faces the inside of the battery cell 20. Exemplarily, the first surface 2411 and the second surface 2412 are parallel planes.

[0075] In the embodiment of the present application, there is no restriction on the number of the pressure relief grooves 242 on the first surface 2411 and the second surface 2412. The number of the pressure relief grooves 242 on the first surface 2411 and the second surface 2412 can be one or more, as long as the pressure relief grooves 242 on the first surface 2411 correspond to the pressure relief grooves 242 on the second surface 2412 one-to-one. The pressure relief grooves 242 can be formed in a variety of ways, such as stamping, milling, etc., and the embodiment of the present application does not impose any special restrictions on this. The pressure relief groove 242 can be a straight groove extending along a straight line, or a bent groove or an arc-shaped groove extending along the circumferential direction Y of the pressure relief body 241, wherein the bent groove can be a polygonal groove, such as a rectangular groove.

[0076] The weak portion 2413 is the portion of the pressure relief body 241 located between the two pressure relief grooves 242 , that is, the remaining portion of the pressure relief body 241 where the pressure relief grooves 242 are provided.

[0077] In the embodiment of the present application, the first surface 2411 and the second surface 2412 of the pressure relief body 241 are both provided with a pressure relief groove 242, which can obtain a lower residual thickness, reduce the thickness of the weak portion 2413, make the weak portion 2413 easier to crack, reduce the detonation pressure of the pressure relief device 24, and enable the pressure relief body 241 to relieve pressure in time, reduce the risk of fire, explosion, etc. in the battery cell 20, and effectively improve the safety of the battery cell 20.

[0078] In some embodiments, the distance between the first surface 2411 and the second surface 2412 is a first distance, and the ratio of the minimum thickness of the weak portion 2413 to the first distance is 0.12-0.5.

[0079] The first distance is the thickness of the pressure relief body 241 in the region between the first surface 2411 and the second surface 2412. The weak part 2413 can be an equal-thickness structure with equal thickness in any region, or a variable-thickness structure with different thicknesses in multiple regions. The "minimum thickness of the weak part 2413" does not limit the weak part 2413 to be a variable-thickness structure. When the weak part 2413 is an equal-thickness structure, the thickness at any position of the weak part 2413 is the minimum thickness, and the minimum thickness of the weak part 2413 is also the maximum thickness of the weak part 2413.

[0080] If the ratio of the minimum thickness of the weak part 2413 to the first distance is too small, resulting in a small minimum thickness of the weak part 2413, it will cause the weak part 2413 to crack during the forming process. Even if the weak part 2413 does not crack, the strength of the pressure relief body 241 is poor, and it is easy for the weak part 2413 to crack and relieve pressure in a vibration environment or when the pressure or temperature inside the battery cell 20 is far from reaching the threshold, affecting the service life of the battery cell 20. If the ratio of the minimum thickness of the weak part 2413 to the first distance is too large, resulting in a large minimum thickness of the weak part 2413, it is easy for the weak part 2413 not to crack and relieve pressure when the pressure or temperature inside the battery cell 20 has reached the threshold, and the pressure relief is not timely, leading to accidents such as fire and explosion of the battery cell 20.

[0081] In this embodiment, the ratio of the minimum thickness of the weak part 2413 to the first distance is set to 0.12 - 0.5, which not only ensures that the pressure relief device 24 can relieve pressure in time when the internal pressure of the battery cell 20 reaches the threshold, but also ensures that the pressure relief device 24 has sufficient strength before pressure relief.

[0082] In some embodiments, the pressure relief groove 242 extends along the circumferential direction Y of the pressure relief body 241 and defines a pressure relief portion 2414. The pressure relief portion 2414 is configured to open with the weak part 2413 as the boundary when the pressure or temperature inside the battery cell 20 reaches the threshold, so as to relieve the pressure inside the battery cell 20.

[0083] The pressure relief groove 242 can be a closed-loop structure that extends along the circumferential direction Y of the pressure relief body 241 and is connected end to end. For example, the pressure relief groove 242 is circular, elliptical, rectangular, etc. The pressure relief groove 242 can also be a non-closed-loop structure that extends along the circumferential direction Y of the pressure relief body 241 and has a distance between the head and the tail. For example, the pressure relief groove 242 is "C"-shaped, "匚"-shaped, etc.

[0084] The pressure relief portion 2414 is an area defined by the pressure relief groove 242 on the pressure relief body 241, and the weak portion 2413 is located at the edge of the pressure relief portion 2414. When the pressure or temperature inside the battery cell 20 reaches a threshold value, the weak portion 2413 will crack, causing the pressure relief portion 2414 to open with the weak portion 2413 as the boundary. After the pressure relief portion 2414 is opened, an opening will be formed in the pressure relief body 241 at a position corresponding to the pressure relief portion 2414, and the emissions (gas, electrolyte, etc.) inside the battery cell 20 can be discharged through the opening to achieve the purpose of releasing the pressure inside the battery cell 20. During the opening process of the pressure relief portion 2414, the pressure relief portion 2414 can be opened by separating from the pressure relief body 241, or it can be flipped open from the inside to the outside.

[0085] In this embodiment, the pressure relief groove 242 extends axially along the pressure relief body 241 and defines a pressure relief portion 2414, which effectively increases the pressure relief area of the pressure relief device 24, thereby increasing the pressure relief rate of the pressure relief device 24, reducing the risk of fire, explosion, etc. in the battery cell 20, and improving the safety of the battery cell 20.

[0086] In some embodiments, along the circumferential direction Y of the pressure relief body 241 , there is a distance between the two ends of the pressure relief groove 242 .

[0087] There is a distance between the two ends of the pressure relief groove 242 along the circumferential direction Y of the pressure relief body 241 , that is, there is a distance between the two ends of the pressure relief groove 242 in its extension direction. It can be understood that the pressure relief groove 242 is a non-closed structure with a distance between the head and the tail.

[0088] In this embodiment, there is a distance between the two ends of the pressure relief groove 242 in the circumferential direction Y of the pressure relief body 241. When the weak portion 2413 cracks to release pressure, the area between the two ends of the pressure relief groove 242 will not crack, so that the pressure relief portion 2414 can be opened in an outward flipping manner, preventing the pressure relief portion 2414 from falling off and flying out as a whole during pressure release.

[0089] In some embodiments, the pressure relief groove 242 is in an arc shape extending along the circumferential direction Y of the pressure relief body 241 .

[0090] like Figure 2 As shown, taking the circular shape of the pressure relief body 241 as an example, the pressure relief groove 242 can be coaxially arranged with the pressure relief body 241 .

[0091] Exemplarily, the central angle of the pressure relief groove 242 is not less than 180°. Preferably, the central angle of the pressure relief groove 242 is greater than 270°.

[0092] In this embodiment, the pressure relief groove 242 is in an arc shape. The pressure relief groove 242 of this structure has a regular shape and is easy to process and shape, so that the pressure relief portion 2414 can open regularly when releasing pressure.

[0093] In some embodiments, please refer to Figure 5 The pressure relief body 241 further has an outer surface 2415 and an inner surface 2416. Along the thickness direction Z of the pressure relief device 24, the outer surface 2415 and the inner surface 2416 are disposed opposite each other. The pressure relief portion 2414 is configured to open from the inner surface 2416 toward the outer surface 2415 when the pressure or temperature inside the battery cell 20 reaches a threshold. A recess 2415a is provided on the pressure relief body 241. Along the thickness direction Z of the pressure relief device 24, the recess 2415a is recessed from the outer surface 2415 toward the inner surface 2416. The bottom surface of the recess 2415a forms the first surface 2411.

[0094] In the battery cell 20, the outer surface 2415 is the surface of the pressure relief body 241 facing the outside of the battery cell 20, and the inner surface 2416 is the surface of the pressure relief body 241 facing the inside of the battery cell 20. The recess 2415a is recessed from the outer surface 2415 toward the inner surface 2416. The bottom surface of the recess 2415a forms a first surface 2411, which is a stepped surface of the pressure relief body 241. The recess 2415a can have various shapes, such as circular, rectangular, etc.

[0095] In the battery cell 20 , when the pressure or temperature inside the battery cell 20 reaches a threshold, the pressure relief portion 2414 will open from the inner surface 2416 toward the outer surface 2415 , that is, the pressure relief portion 2414 will open from the inside of the battery cell 20 to the outside.

[0096] In the thickness direction Z of the pressure relief body 241, the distance between the outer surface 2415 and the inner surface 2416 is a second distance. The second distance and the first distance may be equal or different. If the second distance and the first distance are different, the second distance may be greater than the first distance or smaller than the first distance.

[0097] In this embodiment, a recess 2415a is provided on the pressure relief body 241, which can provide an escape space for the pressure relief part 2414 when it opens outward. Even if there is an obstruction on the outer surface 2415 of the pressure relief body 241, the pressure relief part 2414 can be ensured to open normally, thereby reducing the risk of the pressure relief part 2414 being unable to open due to the interference between the obstruction and the outer surface 2415.

[0098] In some embodiments, a convex portion 2416a is formed on the inner surface 2416 at a position corresponding to the concave portion 2415a of the pressure relief body 241. Along the thickness direction Z of the pressure relief device 24, the surface of the convex portion 2416a facing away from the inner surface 2416 forms a second surface 2412.

[0099] The shape of the convex portion 2416a can be adapted to the shape of the concave portion 2415a. For example, if the concave portion 2415a is circular, the convex portion 2416a can be configured as a corresponding circular shape. For another example, if the concave portion 2415a is rectangular, the convex portion 2416a can be configured as a corresponding rectangular shape. The convex portion 2416a has an outer peripheral surface connected between the second surface 2412 and the inner surface 2416, and the outer peripheral surface is located on the outer periphery of the concave portion 2415a. For example, if both the concave portion 2415a and the convex portion 2416a are circular, the concave portion 2415a and the convex portion 2416a are arranged coaxially, and the diameter of the outer peripheral surface of the convex portion 2416a is larger than the diameter of the concave portion 2415a.

[0100] In actual production, a concave portion 2415 a may be formed on one side of the pressure relief body 241 by stamping, and a convex portion 2416 a may be correspondingly formed on the other side of the pressure relief body 241 .

[0101] In this embodiment, a convex portion 2416a is formed on the inner surface 2416 at a position corresponding to the concave portion 2415a of the pressure relief body 241. The setting of the convex portion 2416a can improve the strength of the area where the concave portion 2415a is set on the pressure relief body 241, thereby avoiding the problem of insufficient local strength caused by the setting of the concave portion 2415a on the pressure relief body 241.

[0102] In some embodiments, please refer to Figure 6 , Figure 6 for Figure 4 In the AA cross-sectional view of the pressure relief device 24, a welding groove 2415b is provided on the outer surface 2415. A protrusion 2416b is formed on the inner surface 2416 of the pressure relief body 241 at a position corresponding to the welding groove 2415b. Both the welding groove 2415b and the protrusion 2416b are located on the periphery of the protrusion 2416a. The protrusion 2416b is used to abut and weld with the current collecting member 26.

[0103] Illustratively, the welding groove 2415b and the protrusion 2416b are both annular structures arranged around the convex portion 2416a.

[0104] In this embodiment, the pressure relief body 241 can serve as the end cap 23 in the battery cell 20 to cover the opening of the housing 22. When welding the pressure relief body 241 to the current collecting member 26, the pressure relief body 241 can be welded in the welding groove 2415b area to weld the protrusion 2416b to the current collecting member 26. The weld mark formed by the welding of the protrusion 2416b and the current collecting member 26 will be formed in the welding groove 2415b.

[0105] In some embodiments, please refer to Figure 7 and Figure 8 , Figure 7 This is a partial enlarged view of the pressure relief device 24 provided in some embodiments of the present application. Figure 8 This is a partial enlarged view of a pressure relief device 24 provided in another embodiment of the present application. The pressure relief groove 242 includes a groove bottom surface 2422 and two groove side surfaces 2421. Along the width direction X of the pressure relief groove 242, the two groove side surfaces 2421 face each other. The groove bottom surface 2422 is connected to the two groove side surfaces 2421. The area between the groove bottom surfaces 2422 of the two pressure relief grooves 242 forms a weak portion 2413.

[0106] The two groove side surfaces 2421 of the pressure relief groove 242 can be parallel to each other or can be inclined to each other. The groove bottom surface 2422 of the pressure relief groove 242 can be a flat surface or a curved surface.

[0107] In this embodiment, the pressure relief groove 242 is easy to be processed and formed, and the pressure relief groove 242 can be formed by stamping.

[0108] In some embodiments, please refer to Figure 7 The groove bottom surface 2422 is an arc surface that is recessed along the depth direction of the pressure relief groove 242 .

[0109] It is understood that for the pressure relief groove 242 disposed on the first surface 2411, the depth direction of the pressure relief groove 242 is the direction from the first surface 2411 to the second surface 2412. For the pressure relief groove 242 disposed on the second surface 2412, the depth direction of the pressure relief groove 242 is the direction from the second surface 2412 to the first surface 2411.

[0110] In this embodiment, the distance between the arc vertices of the groove bottom surfaces 2422 of the two pressure relief grooves 242 is the minimum thickness of the weak portion 2413 .

[0111] Exemplarily, the groove bottom surface 2422 is tangent to both groove side surfaces 2421 of the pressure relief groove 242 .

[0112] In this embodiment, the groove bottom surface 2422 is an arc surface that is recessed along the depth direction of the pressure relief groove 242, so that the weak portion 2413 is a structure with a thickness gradually decreasing from both sides to the middle position, so that the weak portion 2413 can crack from the weakest position in the middle during pressure relief, making the weak portion 2413 easier to crack, ensuring that the weak portion 2413 can crack and release pressure in time when the pressure or temperature of the pressure relief device 24 inside the battery cell 20 reaches a threshold.

[0113] In some embodiments, please refer to Figure 8 The groove bottom surface 2422 includes a bottom plane 2422a and an arc-shaped chamfered surface 2422b, and the bottom plane 2422a is connected to each groove side surface 2421 through an arc-shaped chamfered surface 2422b.

[0114] In this embodiment, the distance between the bottom planes 2422 a of the two pressure relief grooves 242 is the minimum thickness of the weak portion 2413 .

[0115] Exemplarily, the bottom plane 2422a and the groove side surface 2421 are both tangent to the arcuate chamfered surface 2422b. In the pressure relief groove 242, along the width direction X of the pressure relief groove 242, two arcuate chamfered surfaces 2422b connected to the two groove side surfaces 2421 are symmetrically arranged.

[0116] In this embodiment, the bottom plane 2422a is connected to each groove side 2421 through an arc-shaped chamfered surface 2422b, which is easy to process and form, so that there is a smooth transition between the groove side 2421 and the bottom plane 2422a. This structure makes the middle area of the weak portion 2413 (the area corresponding to the weak portion 2413 and the bottom plane 2422a) the weakest, making the weak portion 2413 easier to crack, ensuring that the weak portion 2413 can crack and release pressure in time when the pressure or temperature inside the battery cell 20 reaches a threshold.

[0117] In some embodiments, please refer to Figure 7 and Figure 8 , along the depth direction of the pressure relief groove 242, the distance between the two groove side surfaces 2421 gradually decreases.

[0118] Exemplarily, both groove side surfaces 2421 of the pressure relief groove 242 are inclined planes, and along the width direction X of the pressure relief groove 242 , the two groove side surfaces 2421 are symmetrically arranged.

[0119] In this embodiment, the distance between the two groove side surfaces 2421 gradually decreases along the depth direction of the pressure relief groove 242. This structure can effectively reduce the width of the weak portion 2413, making the weak portion 2413 easier to crack when the pressure or temperature inside the battery cell 20 reaches a threshold.

[0120] In some embodiments, please refer to Figure 9 , Figure 9 This is a partial cross-sectional view of the pressure relief device 24 provided in some other embodiments of the present application. An anti-oxidation layer 2417 is formed on the surface of the pressure relief body 241. The anti-oxidation layer 2417 extends along the groove wall of the pressure relief groove 242 in the area where the pressure relief groove 242 is set.

[0121] For example, the anti-oxidation layer 2417 may be a metal coating located on the surface of the pressure relief body 241. For example, the pressure relief body 241 is a steel layer, and the anti-oxidation layer 2417 is a nickel layer coated on the pressure relief body 241.

[0122] The anti-oxidation layer 2417 protects the pressure relief body 241 from oxidation. Furthermore, since the anti-oxidation layer 2417 extends along the wall of the pressure relief groove 242 in the area where the pressure relief groove 242 is located, the anti-oxidation layer 2417 also protects the area where the pressure relief groove 242 is located, thereby reducing the risk of oxidation of the pressure relief body 241 in the area where the pressure relief groove 242 is located, which could weaken the strength of the weak portion 2413.

[0123] In some embodiments, the thickness of the anti-oxidation layer 2417 in the pressure relief groove 242 region is smaller than the thickness of the anti-oxidation layer 2417 in other regions.

[0124] The remaining area refers to the area of the pressure relief body 241 excluding the pressure relief groove 242 area.

[0125] Exemplarily, the thickness of the anti-oxidation layer 2417 in the area corresponding to the bottom surface 2422 of the pressure relief groove 242 is greater than the thickness of the anti-oxidation layer 2417 in the area corresponding to the side surface 2421 of the pressure relief groove 242 to improve the anti-oxidation ability of the weak portion 2413.

[0126] In this embodiment, the thickness of the anti-oxidation layer 2417 in the pressure relief groove 242 area is less than the thickness of the anti-oxidation layer 2417 in other areas, reducing the impact of the anti-oxidation layer 2417 in the pressure relief groove 242 area on the weak portion 2413, and ensuring that the weak portion 2413 can be cracked and pressure released in time when the pressure or temperature inside the battery cell 20 reaches a threshold.

[0127] The embodiment of the present application provides a battery cell 20, comprising an electrode assembly 21 and a housing, wherein the housing is used to accommodate the electrode assembly 21. The housing includes the pressure relief device 24 provided in any one of the above embodiments.

[0128] In some embodiments, the housing further includes a shell 22 , which is used to accommodate the electrode assembly 21 . The shell 22 has an opening, and the pressure relief body 241 is used to cover the opening.

[0129] It can be understood that in this embodiment, the pressure relief body 241 is the end cover 23 .

[0130] An embodiment of the present application provides a battery 100 , comprising a housing 10 and a battery cell 20 provided in any one of the above embodiments. The housing 10 is used to accommodate the battery cell 20 .

[0131] An embodiment of the present application provides an electrical device, comprising the battery 100 provided in any one of the above embodiments.

[0132] In addition, please refer to Figure 4 and Figure 5The present embodiment provides a pressure relief device 24 for covering the opening of the housing 22 of a battery cell 20. The pressure relief device 24 includes a pressure relief body 241 and two pressure relief grooves 242. The pressure relief body 241 is circular and has a first surface 2411 and a second surface 2412 disposed opposite each other along its thickness direction Z. The two pressure relief grooves 242 are disposed opposite each other along the thickness direction Z of the pressure relief body 241, and are disposed on the first surface 2411 and the second surface 2412, respectively. A weak portion 2413 is formed between the two pressure relief grooves 242. The pressure relief grooves 242 extend along the circumferential direction Y of the pressure relief body 241 and define a pressure relief portion 2414. A distance exists between the two ends of the pressure relief grooves 242 along the circumferential direction Y of the pressure relief body 241. The pressure relief portion 2414 is configured to open with the weak portion 2413 as a boundary when the pressure or temperature inside the battery cell 20 reaches a threshold value, thereby releasing the pressure inside the battery cell 20.

[0133] In this pressure relief device 24, pressure relief grooves 242 are provided on both the first surface 2411 and the second surface 2412 of the pressure relief body 241. This reduces the residual thickness and the thickness of the weak portion 2413, making it easier for the weak portion 2413 to rupture. This reduces the detonation pressure of the pressure relief device 24 and enables the pressure relief body 241 to release pressure in a timely manner, thereby reducing the risk of fire or explosion in the battery cell 20 and effectively improving the safety of the battery cell 20. Furthermore, when the weak portion 2413 ruptures to release pressure, the area between the two ends of the pressure relief groove 242 does not rupture, allowing the pressure relief portion 2414 to open by flipping outward, preventing the entire pressure relief portion 2414 from falling off during pressure relief.

[0134] Please refer to Figure 10 , Figure 10 This is a flow chart of a method for manufacturing a pressure relief device 24 provided in some embodiments of the present application. The present application provides a method for manufacturing a pressure relief device 24, and the manufacturing method includes:

[0135] S100: providing a pressure relief body 241 , wherein the pressure relief body 241 has a first surface 2411 and a second surface 2412 oppositely disposed along a thickness direction Z thereof;

[0136] S200: Processing a pressure relief groove 242 on the first surface 2411 and the second surface 2412 of the pressure relief body 241, so that the pressure relief groove 242 on the first surface 2411 and the pressure relief groove 242 on the second surface 2412 are relatively arranged along the thickness direction Z of the pressure relief device 24, and a weak portion 2413 is formed between the pressure relief groove 242 on the first surface 2411 and the pressure relief groove 242 on the second surface 2412, and the weak portion 2413 is configured to rupture when the pressure or temperature inside the battery cell 20 reaches a threshold value to release the pressure inside the battery cell 20.

[0137] It should be noted that the relevant structure of the pressure relief device 24 manufactured by the manufacturing method provided in the above embodiment can be referred to the pressure relief device 24 provided in the above embodiments, and will not be repeated here.

[0138] Please refer to Figure 11 , Figure 11 This is a schematic block diagram of a manufacturing device 2000 for a pressure relief device 24 provided in some embodiments of the present application. The embodiments of the present application also provide a manufacturing device 2000 for a pressure relief device 24, and the manufacturing device 2000 includes a providing device 2100 and a processing device 2200.

[0139] The providing device 2100 is used to provide a pressure relief body 241, which has a first surface 2411 and a second surface 2412 disposed opposite each other along its thickness direction Z. The processing device 2200 is used to process pressure relief grooves 242 on the first surface 2411 and the second surface 2412, such that the pressure relief grooves 242 on the first surface 2411 and the pressure relief grooves 242 on the second surface 2412 are disposed opposite each other along the thickness direction Z of the pressure relief device 24, and a weak portion 2413 is formed between the pressure relief grooves 242 on the first surface 2411 and the pressure relief grooves 242 on the second surface 2412. The weak portion 2413 is configured to rupture when the pressure or temperature inside the battery cell 20 reaches a threshold value, thereby releasing the pressure inside the battery cell 20.

[0140] It should be noted that the relevant structure of the pressure relief device 24 manufactured by the manufacturing equipment 2000 provided by the above embodiment can be referred to the pressure relief device 24 provided by the above embodiments, and will not be repeated here.

[0141] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0142] The above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit this application. Those skilled in the art will appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application are intended to be within the scope of protection of this application.

Claims

1. A pressure relief device for a battery cell, characterized in that: include: The pressure relief body has a first surface and a second surface arranged opposite to each other along a thickness direction thereof; two pressure relief grooves, disposed opposite to each other along the thickness direction and respectively disposed on the first surface and the second surface, with a weak portion formed between the two pressure relief grooves, the weak portion being configured to rupture when the pressure or temperature inside the battery cell reaches a threshold value to release the pressure inside the battery cell; The pressure relief groove includes a groove bottom surface and two groove side surfaces. Along the width direction of the pressure relief groove, the two groove side surfaces are arranged facing each other, and the groove bottom surface is connected to the two groove side surfaces. The area between the groove bottom surfaces of the two pressure relief grooves forms the weak portion. An anti-oxidation layer is formed on the surface of the pressure relief body, and the anti-oxidation layer extends along the groove wall of the pressure relief groove in the area where the pressure relief groove is set. The thickness of the anti-oxidation layer in the pressure relief groove area is less than the thickness of the anti-oxidation layer in the remaining areas, and the thickness of the anti-oxidation layer in the area corresponding to the groove bottom surface of the pressure relief groove is greater than the thickness of the anti-oxidation layer in the area corresponding to the groove side surface of the pressure relief groove.

2. The pressure relief device according to claim 1, characterized in that: The distance between the first surface and the second surface is a first distance, and the ratio of the minimum thickness of the weak portion to the first distance is 0.12-0.

5.

3. The pressure relief device according to claim 1, characterized in that: The pressure relief groove extends along the circumference of the pressure relief body and defines a pressure relief portion; The pressure relief portion is configured to open with the weak portion as a boundary when the pressure or temperature inside the battery cell reaches a threshold value, so as to relieve the pressure inside the battery cell.

4. The pressure relief device according to claim 3, characterized in that: Along the circumference of the pressure relief body, there is a distance between the two ends of the pressure relief groove.

5. The pressure relief device according to claim 3, characterized in that: The pressure relief groove is in an arc shape extending along the circumference of the pressure relief body.

6. The pressure relief device according to claim 3, characterized in that: The pressure relief body further comprises an outer surface and an inner surface, wherein the outer surface is arranged opposite to the inner surface along the thickness direction, and the pressure relief portion is configured to open in a direction from the inner surface to the outer surface when the pressure or temperature inside the battery cell reaches a threshold value; The pressure relief body is provided with a recessed portion. Along the thickness direction, the recessed portion is recessed from the outer surface in a direction close to the inner surface. The bottom surface of the recessed portion forms the first surface.

7. The pressure relief device according to claim 6, characterized in that: A convex portion protruding from the inner surface is formed at a position of the pressure relief body corresponding to the concave portion, and along the thickness direction, a surface of the convex portion away from the inner surface forms the second surface.

8. The pressure relief device according to any one of claims 1 to 7, characterized in that: The bottom surface of the groove is an arc surface that is concave along the depth direction of the pressure relief groove.

9. The pressure relief device according to any one of claims 1 to 7, characterized in that: The bottom surface of the groove includes a bottom plane and an arc-shaped chamfered surface, and the bottom plane is connected to each of the groove side surfaces through one of the arc-shaped chamfered surfaces.

10. The pressure relief device according to any one of claims 1 to 7, characterized in that: Along the depth direction of the pressure relief groove, the distance between the two groove side surfaces gradually decreases.

11. A battery cell, characterized in that: include; electrode assembly; A shell is used to accommodate the electrode assembly, and the shell includes the pressure relief device according to any one of claims 1 to 10.

12. The battery cell according to claim 11, characterized in that The housing further includes a shell, which is used to accommodate the electrode assembly. The shell has an opening, and the pressure relief body is used to cover the opening.

13. A battery, characterized in that: include: The battery cell according to claim 11 or 12; The box is used to accommodate the battery cells.

14. An electrical device, characterized in that: Including the battery according to claim 13.

15. A method for manufacturing a pressure relief device, characterized in that: The manufacturing method comprises: Providing a pressure relief body, the pressure relief body having a first surface and a second surface oppositely disposed along a thickness direction thereof; Pressure relief grooves are machined on the first surface and the second surface, such that the pressure relief grooves on the first surface and the pressure relief grooves on the second surface are arranged opposite to each other along the thickness direction, and a weak portion is formed between the pressure relief grooves on the first surface and the pressure relief grooves on the second surface. The weak portion is configured to rupture when the pressure or temperature inside the battery cell reaches a threshold value to release the pressure inside the battery cell, wherein the pressure relief groove includes a groove bottom surface and two groove side surfaces. The two groove side surfaces are arranged facing each other along the width direction of the pressure relief groove, the groove bottom surface is connected to the two groove side surfaces, and the area between the groove bottom surfaces of the two pressure relief grooves forms the weak portion. An anti-oxidation layer is formed on the surface of the pressure relief body, and the anti-oxidation layer extends along the groove wall surface of the pressure relief groove in the area where the pressure relief groove is provided. The thickness of the anti-oxidation layer in the pressure relief groove area is less than the thickness of the anti-oxidation layer in the remaining area, and the thickness of the anti-oxidation layer in the area corresponding to the groove bottom surface of the pressure relief groove is greater than the thickness of the anti-oxidation layer in the area corresponding to the groove side surface of the pressure relief groove.

16. A manufacturing device for a pressure relief device, characterized in that: The manufacturing equipment includes: Providing an apparatus for providing a pressure relief body, wherein the pressure relief body has a first surface and a second surface disposed opposite to each other along a thickness direction thereof; A processing device is used to process pressure relief grooves on the first surface and the second surface, so that the pressure relief grooves on the first surface and the pressure relief grooves on the second surface are arranged opposite to each other along the thickness direction, and a weak portion is formed between the pressure relief grooves on the first surface and the pressure relief grooves on the second surface, and the weak portion is configured to rupture when the pressure or temperature inside the battery cell reaches a threshold value to release the pressure inside the battery cell, wherein the pressure relief groove includes a groove bottom surface and two groove side surfaces, and the two groove side surfaces are arranged facing each other along the width direction of the pressure relief groove, the groove bottom surface is connected to the two groove side surfaces, and the area between the groove bottom surfaces of the two pressure relief grooves forms the weak portion; an anti-oxidation layer is formed on the surface of the pressure relief body, and the anti-oxidation layer extends along the groove wall surface of the pressure relief groove in the area where the pressure relief groove is provided, and the thickness of the anti-oxidation layer in the pressure relief groove area is less than the thickness of the anti-oxidation layer in the remaining area, and the thickness of the anti-oxidation layer in the area corresponding to the groove bottom surface of the pressure relief groove is greater than the thickness of the anti-oxidation layer in the area corresponding to the groove side surface of the pressure relief groove.

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