Pressure relief device, battery cell, battery 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. Among them, the pressure relief device includes a pressure relief portion and a multi-stage notched groove, and the pressure relief portion has a first surface and a second surface relative to each other in the thickness direction. The multi-stage notched grooves are sequentially arranged on the pressure relief portion along the direction from the first surface to the second surface. In the two adjacent notched grooves in the thickness direction, the first-stage notched groove far away from the first surface is arranged on the bottom surface of the first-stage notched groove close to the first surface. The pressure relief device of this structure adopts a multi-stage notched groove structure, which can reduce the forming depth of each stage of the notched groove, thereby reducing the forming force on the pressure relief portion when forming each stage of the notched groove, reducing the risk of cracks in the pressure relief portion, and the pressure relief device is not easy to fail due to cracks in the pressure relief portion at the position where the notched groove is set, thereby improving the long-term reliability of the pressure relief device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of international patent application PCT / CN2021 / 115766, entitled “Pressure relief device, battery cell, battery and electrical equipment”, filed on August 31, 2021, and the entire contents of that application are incorporated herein by reference. Technical Field

[0003] 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

[0004] Batteries are widely used in electronic devices, such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes and power tools, etc.

[0005] In battery technology, to ensure the safety of battery cells, a pressure relief device is generally installed in the battery cells. When the temperature inside the battery cells reaches a threshold, the pressure relief device ruptures at the location where the notch groove is set to release the pressure inside the battery cells. For general pressure relief devices, pressure relief may occur even when the internal pressure of the battery cells is within the normal range, and the long-term reliability is poor. Summary of the invention

[0006] 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 long-term reliability of the pressure relief device.

[0007] In a first aspect, an embodiment of the present application provides a pressure relief device, comprising a pressure relief portion and a multi-stage notched groove, the pressure relief portion having a first surface and a second surface relative to each other in a thickness direction thereof; the multi-stage notched grooves are sequentially arranged on the pressure relief portion along a direction from the first surface to the second surface, and in two adjacent notched grooves in the thickness direction, a first-stage notched groove away from the first surface is arranged on a bottom surface of a first-stage notched groove close to the first surface.

[0008] In the above technical solution, a multi-level notch groove is provided on the pressure relief part, and the multi-level notch grooves are arranged in sequence on the pressure relief part along the direction from the first surface to the second surface of the pressure relief part, and the first-level notch groove far away from the first surface is arranged on the bottom surface of the first-level notch groove close to the first surface. The pressure relief device with this structure adopts a multi-level notch groove structure, which can reduce the forming depth of each level of notch groove, thereby reducing the forming force applied to the pressure relief part when forming each level of notch groove, reducing the risk of cracks in the pressure relief part, and the pressure relief device is not easy to fail due to cracks in the pressure relief part at the position where the notch groove is set, thereby improving the long-term reliability of the pressure relief device.

[0009] In some embodiments, the multi-level notched groove includes at least one first-level notched groove, the first-level notched groove includes a first groove segment, a second groove segment, and a third groove segment, the first groove segment and the second groove segment are arranged opposite to each other, and the first groove segment and the second groove segment both intersect with the third groove segment; the pressure relief portion includes an opening area, the first groove segment, the second groove segment, and the third groove segment are arranged along the edge of the opening area, and the opening area is configured to be able to be opened with the first groove segment, the second groove segment, and the third groove segment as boundaries. In this way, the opening area can be opened with the first groove segment, the second groove segment, and the third groove segment as boundaries, thereby increasing the pressure relief area of ​​the pressure relief portion and improving the pressure relief rate of the pressure relief portion.

[0010] In some embodiments, the first-level notched groove further includes a fourth groove segment, the fourth groove segment is located between the first groove segment and the second groove segment, and the fourth groove segment intersects with the third groove segment. The stress of the pressure relief portion is more concentrated at the intersection of the third groove segment and the fourth groove segment, and it is easier to rupture, so that the pressure relief portion ruptures along the third groove segment from the intersection of the third groove segment and the fourth groove segment during the pressure relief process, and ruptures along the first groove segment and the second groove segment after the third groove segment ruptures, so as to achieve rapid pressure relief.

[0011] In some embodiments, in the extension direction of the third slot segment, the distance from the intersection position of the fourth slot segment and the third slot segment to the first slot segment is equal to the distance from the intersection position of the fourth slot segment and the third slot segment to the second slot segment. In this way, the pressure relief portion can be broken along the third slot segment at the intersection position of the fourth slot segment and the third slot segment, and then broken along the first slot segment and the second slot segment synchronously, so that the opening area can be opened more quickly.

[0012] In some embodiments, the first slot segment, the second slot segment and the third slot segment define at least one opening area. The opening area is defined by the first slot segment, the second slot segment and the third slot segment, and the opening area can be opened in a flipping manner. After the opening area is opened, it is always connected to other areas of the pressure relief part and is not easy to fall off, thereby reducing the risk of splashing after the opening area is opened.

[0013] In some embodiments, the first slot segment, the second slot segment, and the third slot segment define two opening areas, and the two opening areas are respectively located on both sides of the third slot segment. During the pressure relief process, the pressure relief portion in the two opening areas can be opened in a split manner to relieve pressure, thereby increasing the pressure relief area and effectively improving the pressure relief rate of the pressure relief portion.

[0014] In some embodiments, a notch groove is provided on the second surface in the opening area, and there is a distance between the notch groove and the third groove section in the extending direction of the first groove section. In this way, during the pressure relief process, a part of the pressure relief section located in the opening area can be turned around the position of the pressure relief section located in the notch groove as an axis, making it easier to open the pressure relief.

[0015] In some embodiments, the multi-level notch groove includes a first-level notch groove. The multi-level notch groove has only one first-level notch groove, which is simple to form, improves production efficiency, and is conducive to reducing production costs.

[0016] In some embodiments, the multi-level notched grooves include multi-level first-level notched grooves, and the multi-level first-level notched grooves are sequentially arranged along the direction from the first surface to the second surface. The multi-level first-level notched grooves are sequentially arranged along the direction from the first surface to the second surface, which can reduce the forming depth of each level of the first-level notched grooves, thereby reducing the forming force on the pressure relief part when forming each level of the first-level notched grooves, and reducing the risk of cracks in the pressure relief part. In the process of machining the first-level notched grooves step by step along the direction from the first surface to the second surface, the hardness of the residual part of the pressure relief part where the first-level notched groove is set increases with each machining of the first-level notched grooves, thereby improving the hardness of the residual part of the pressure relief part after the multi-level first-level notched grooves are set, so that the long-term reliability is better, the impact resistance is better, and the probability of damage by external force impact is reduced.

[0017] In some embodiments, the outermost first-level scoring groove is disposed on the first surface. The outermost first-level scoring groove can be directly formed on the first surface, which simplifies the structure of the pressure relief device and reduces the production cost.

[0018] In some embodiments, the multi-level score groove includes two levels of first level score grooves.

[0019] In some embodiments, the multi-level notched groove further includes at least one second-level notched groove, and the at least one second-level notched groove and the at least one first-level notched groove are arranged in sequence along the direction from the first surface to the second surface; wherein the opening area is formed on the bottom wall of the first-level second-level notched groove farthest from the first surface. During molding, the second-level notched groove can be first molded on the pressure relief portion, so that the pressure relief portion is thinned as a whole in the area where the second-level notched groove is set, and the hardness of the residual part of the area is increased; then, the first-level notched groove is molded on the pressure relief portion, so that the hardness of the residual part of the pressure relief portion at the position of the first-level notched groove is further increased, so that the long-term reliability is better, the impact resistance is better, and the probability of damage by external force impact is reduced. In addition, since the opening area is formed on the bottom wall of the first-level second-level notched groove farthest from the first surface, the second-level notched groove can provide an escape space for the opening of the opening area, and even if the first surface is blocked by an obstacle, the opening area can still be opened to release pressure.

[0020] In some embodiments, the multi-level notch groove includes a first-level and a second-level notch groove, and the second-level notch groove is arranged on the first surface. The pressure relief portion is provided with a first-level and a second-level notch groove, which is simple to form, improves production efficiency, and reduces production cost.

[0021] In some embodiments, the multi-level notched grooves include multi-level second-level notched grooves, and the multi-level second-level notched grooves are arranged in sequence from the first surface to the second surface, and the outermost second-level notched grooves are arranged on the first surface. The pressure relief portion is provided with multi-level second-level notched grooves, which can make the forming depth of each level of the second-level notched grooves relatively shallow, and can reduce the forming force received by the pressure relief portion when forming each level of the second-level notched grooves, and reduce the risk of cracks in the pressure relief portion. When the multi-level second-level notched grooves are processed step by step from the first surface to the second surface, the hardness of the residual part of the pressure relief portion in the area where the second-level notched grooves are set increases with each processing of the second-level notched grooves, so that the hardness of the residual part of the pressure relief portion in the area of ​​the first-level notched grooves is further increased.

[0022] In some embodiments, the second-level notch groove is a circular groove or a rectangular groove. The second-level notch groove has a simple structure, is easy to form, and can provide more avoidance space for opening the opening area.

[0023] In some embodiments, each level of the notched groove includes at least one groove segment, and in two adjacent groove segments in the thickness direction, the maximum width of a groove segment away from the first surface is smaller than the minimum width of a groove segment close to the first surface. During molding, the groove segments of each level of the notched groove can be molded sequentially from the first surface to the second surface, which facilitates the molding of the groove segments of each level of the notched groove.

[0024] In some embodiments, the distance between the first surface and the second surface is H 0 , the distance from the bottom of the primary notch closest to the second surface to the second surface is H 1 , satisfying: H 1 / H 0 In this way, the residual thickness of the pressure relief portion in the area where the primary notch groove closest to the second surface is arranged accounts for a smaller proportion of the total thickness of the pressure relief portion, so that the portion between the bottom surface of the primary notch groove closest to the second surface and the second surface can be normally ruptured to achieve pressure relief.

[0025] In some embodiments, the distance from the bottom surface of the primary notch closest to the second surface to the second surface is H 1 , satisfying: H 1 <0.5mm. This makes the residual thickness of the pressure relief portion in the area where the primary notch groove closest to the second surface is arranged smaller, making it easier to rupture and release pressure.

[0026] In some embodiments, the depth of the primary notch groove disposed on the first surface is H 2 , satisfying: H 2 <1mm. This makes the depth of the first-level notch groove on the outermost side of the pressure relief part smaller, reduces the forming force on the pressure relief part in the notch groove at this level during the forming process, and reduces the risk of cracks in the pressure relief part.

[0027] In some embodiments, the depth of each level of the scoring groove between the primary scoring groove closest to the second surface and the primary scoring groove disposed on the first surface is H. 3 , satisfying: H 3 <1.5mm. The depth of each level of notch groove on the pressure relief part, except for the first level notch groove closest to the second surface and the first level notch groove arranged on the first surface, is small, thereby reducing the forming force on the pressure relief part during the forming process and reducing the risk of cracks in the pressure relief part.

[0028] In some embodiments, only one level of notch groove is provided between the level of notch groove closest to the second surface and the level of notch groove provided on the first surface, so that three levels of notch grooves are provided on the pressure relief portion, which has a simple structure, can reduce the forming depth of each level of notch groove, and reduce the risk of cracks in the pressure relief portion.

[0029] In some embodiments, a receiving space is formed inside the pressure relief device, and the pressure relief device has a plurality of walls defining the receiving space, the receiving space is used to accommodate the electrode assembly, and at least one of the plurality of walls is formed with a pressure relief portion. The pressure relief device of this structure has both the function of accommodating the electrode assembly and the function of pressure relief.

[0030] In some embodiments, the plurality of wall portions include a peripheral wall and a bottom wall, the peripheral wall is arranged around the edge of the bottom wall, the peripheral wall and the bottom wall together define a receiving space, an opening is formed at one end of the peripheral wall opposite to the bottom wall, and a pressure relief portion is formed on the bottom wall, so that the bottom wall of the pressure relief device has a pressure relief function, which is convenient for releasing the pressure inside the receiving space.

[0031] In some embodiments, the peripheral wall and the bottom wall are integrally formed. Since the bottom wall is formed with a pressure relief portion, the peripheral wall and the bottom wall are integrally formed, so that the peripheral wall and the bottom wall with a pressure relief function have good firmness. This integrated design can simplify the molding process and reduce production costs.

[0032] In some embodiments, the first surface is the outer surface of the bottom wall. In this way, the notched groove can be machined on the outer side of the bottom wall to facilitate machining the notched groove on the bottom wall.

[0033] In some embodiments, the pressure relief portion is an end cap, which is used to cover the opening of the housing, so that the end cap has a pressure relief function, and a pressure relief structure is formed by providing a notch groove on the end cap, which has better stability and good long-term reliability.

[0034] In some embodiments, the first surface is a surface of the end cap facing away from the housing.

[0035] In a second aspect, an embodiment of the present application provides a battery cell, comprising the pressure relief device provided in any one embodiment of the first aspect.

[0036] In a third aspect, an embodiment of the present application provides a battery, comprising a battery cell provided by any embodiment of the second aspect.

[0037] 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. 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 A schematic diagram of the structure of a battery provided in some embodiments of the present application;

[0041] Figure 3 An exploded view of a battery cell provided for some embodiments of the present application;

[0042] Figure 4 An axonometric diagram of a pressure relief device provided for some embodiments of the present application;

[0043] Figure 5 for Figure 4 A cross-sectional view of the pressure relief portion shown;

[0044] Figure 6 An axonometric diagram of a pressure relief device provided in some other embodiments of the present application;

[0045] Figure 7 for Figure 6 A partial enlarged view of the pressure relief device at A shown;

[0046] Figure 8 for Figure 7 A partial view of the pressure relief portion shown;

[0047] Fig. 9 for Figure 8 BB sectional view of the pressure relief portion shown;

[0048] Fig.10 An isometric view of a pressure relief device provided in some further embodiments of the present application;

[0049] Fig.11 for Fig.10 A partial enlarged view of the pressure relief device at C shown;

[0050] Fig.12 for Fig.11 DD sectional view of the pressure relief portion shown;

[0051] Fig.13 An axonometric diagram of a pressure relief device provided in some other embodiments of the present application;

[0052] Fig.14 for Fig.13 A partial enlarged view of the pressure relief device at E shown;

[0053] Fig.15 for Fig.14 A partial view of the pressure relief portion shown;

[0054] Fig.16 for Fig.15 FF sectional view of the pressure relief portion shown;

[0055] Fig.17 for Fig.16 A partial enlarged view of the pressure relief portion G shown;

[0056] Fig.18 An axonometric diagram of a pressure relief device provided in other embodiments of the present application;

[0057] Fig.19 for Fig.18 A partial enlarged view of the H portion of the pressure relief device shown.

[0058] Icons: 10-box; 11-first part; 12-second part; 20-battery cell; 21-housing; 22-electrode assembly; 221-positive electrode ear; 222-negative electrode ear; 23-end cover; 231-positive electrode terminal; 232-negative electrode terminal; 24-insulating member; 25-pressure relief device; 251-pressure relief part; 2511-first surface; 2512-second surface; 2513-opening area; 2 52- notched groove; 252a- first-level notched groove; 252b- second-level notched groove; 2521- first groove section; 2522- second groove section; 2523- third groove section; 2524- fourth groove section; 2525- groove bottom wall; 253- notched groove; 254- peripheral wall; 255- bottom wall; 26- current collecting component; 100- battery; 200- controller; 300- motor; 1000- vehicle; Z- thickness direction. DETAILED DESCRIPTION

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] The term "plurality" used in the present application refers to two or more (including two).

[0066] In the present 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 the present application do not limit this. Battery cells may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application do not limit this.

[0067] 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. For example, the battery mentioned in the present application may include a battery module or a battery pack. The battery generally includes a box for encapsulating one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0068] The battery cell includes an electrode assembly and an electrolyte. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode collector. The positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer. The positive electrode collector not coated with the positive electrode active material layer serves as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be 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 electrode collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode collector. The negative electrode collector not coated with the negative electrode active material layer protrudes from the negative electrode collector coated with the negative electrode active material layer. The negative electrode collector not coated with the negative electrode active material layer serves as the negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon or silicon, etc. In order to ensure that a large current can pass without melting, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together. The material of the isolation film may be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly may be a winding structure or a laminated structure, and the embodiments of the present application are not limited thereto.

[0069] The development of battery technology must take into account many 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.

[0070] The pressure relief device on the battery cell has an important impact on the safety of the battery. For example, when a short circuit or overcharge occurs, thermal runaway may occur inside the battery cell, causing a sudden increase in pressure or temperature. In this case, the pressure relief mechanism can be activated to release the internal pressure and temperature to prevent the battery cell from exploding or catching fire.

[0071] The inventors found that in general battery cells, the pressure relief device will also release pressure when the internal pressure of the battery cell is within the normal range, causing the battery cell to fail. The inventors further found that the pressure relief device is generally provided with a notched groove on the pressure relief part. In order to ensure that the pressure relief device can normally release pressure when the internal pressure or temperature of the battery cell reaches the threshold, the notched groove needs to be processed deeper. After the notched groove on the pressure relief part is formed, cracks are easily generated, resulting in the pressure relief device releasing pressure when the internal pressure of the battery cell is within the normal range (not reaching the threshold).

[0072] In view of this, an embodiment of the present application provides a pressure relief device, on which a plurality of levels of notched grooves are arranged in sequence from the first surface to the second surface on the pressure relief portion of the pressure relief device, and in two levels of notched grooves adjacent to each other in the thickness direction, the first-level notched groove away from the first surface is arranged on the bottom surface of the first-level notched groove close to the first surface.

[0073] In such a pressure relief device, a multi-level notch groove structure is adopted, which can reduce the forming depth of each level of notch groove, thereby reducing the forming force applied to the pressure relief part when forming each level of notch groove, reducing the risk of cracks in the pressure relief part, and the pressure relief device is not easily failed due to cracks in the pressure relief part where the notch groove is set, thereby improving the long-term reliability of the pressure relief device.

[0074] The pressure relief device described in the embodiments of the present application is applicable to batteries and electrical equipment using batteries.

[0075] Electrical equipment may be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, electric tools, and the like. Vehicles may be fuel vehicles, gas vehicles, or new energy vehicles, and new energy vehicles may be pure electric vehicles, hybrid vehicles, or extended-range vehicles, and the like; spacecraft include airplanes, rockets, space shuttles, and spacecraft, and the like; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like; 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, and the like. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.

[0076] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0077] Please refer to Figure 1 , Figure 1 The schematic diagram of the structure of the vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 is provided with a battery 100 inside, and the battery 100 can be provided 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 be used as an operating power source of the vehicle 1000.

[0078] The vehicle 1000 may further include a controller 200 and a motor 300 , wherein 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 starting, navigating, and driving the vehicle 1000 .

[0079] In some embodiments of the present application, the battery 100 can not only serve as an operating 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.

[0080] Please refer to Figure 2 , Figure 2 The schematic diagram of the structure of the battery 100 provided in some embodiments of the present application. The battery 100 comprises a box body 10 and a battery cell 20 , wherein the box body 10 is used to accommodate the battery cell 20 .

[0081] Among them, the box body 10 is a component for accommodating the battery cell 20, and the box body 10 provides a storage space for the battery cell 20. The box body 10 can be a variety of structures. In some embodiments, the box body 10 may include a first part 11 and a second part 12, and the first part 11 and the second part 12 cover each other to define a storage space for accommodating the battery cell 20. The first part 11 and the second part 12 can be in a variety of shapes, such as a cuboid, a cylinder, etc. The first part 11 can be a hollow structure with one side open, and the second part 12 can also be a hollow structure with one side open, and the open side of the second part 12 covers the open side of the first part 11, so as to form a box body 10 with a storage space. It can also be that the first part 11 is a hollow structure with one side open, and the second part 12 is a plate-like structure, and the second part 12 covers the open side of the first part 11, so as to form a box body 10 with a storage space. The first part 11 and the second part 12 can be sealed by a sealing element, and the sealing element can be a sealing ring, a sealant, etc.

[0082] In the battery 100, there may be one or more battery cells 20. If there are more than one battery cell 20, the battery cells 20 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the battery cells 20 are connected in series and in parallel. A battery module may be formed by connecting a plurality of battery cells 20 in series, in parallel, or in a mixed connection, and then the plurality of battery modules are connected in series, in parallel, or in a mixed connection to form a whole and accommodated in the box 10. Alternatively, all the battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by all the battery cells 20 is accommodated in the box 10.

[0083] In some embodiments, the battery 100 may further include a busbar, through which multiple battery cells 20 may be electrically connected to each other, so as to realize series connection, parallel connection or mixed connection of multiple battery cells 20. The busbar may be a metal conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0084] Please refer to Figure 3 , Figure 3 The exploded view of the battery cell 20 provided in some embodiments of the present application. The battery cell 20 includes a housing 21, an electrode assembly 22, an end cap 23, an insulating member 24 and a pressure relief device 25 ( Figure 3 not shown).

[0085] The housing 21 is a component for accommodating the electrode assembly 22. The housing 21 may be a hollow structure with an opening formed at one end. The housing 21 may be in various shapes, such as a cylinder, a cuboid, etc. The housing 21 may be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0086] The number of electrode assemblies 22 in the housing 21 may be one or more. For example, as shown in the figure, there are multiple electrode assemblies 22, and the multiple electrode assemblies 22 are stacked and arranged in the housing 21.

[0087] The electrode assembly 22 is a component in the battery cell 20 where an electrochemical reaction occurs. The electrode assembly 22 may include a positive electrode sheet, a negative electrode sheet, and a separator. The electrode assembly 22 may be a wound structure formed by winding the positive electrode sheet, the separator, and the negative electrode sheet, or a stacked structure formed by stacking the positive electrode sheet, the separator, and the negative electrode sheet.

[0088] The positive electrode plate may include a positive electrode current collector and a positive electrode active material layer coated on opposite sides of the positive electrode current collector. The negative electrode plate may include a negative electrode current collector and a negative electrode active material layer coated on opposite sides of the negative electrode current collector. The electrode assembly 22 has a positive electrode tab 221 and a negative electrode tab 222. The positive electrode tab 221 may be a portion of the positive electrode plate that is not coated with the positive electrode active material layer, and the negative electrode tab 222 may be a portion of the negative electrode plate that is not coated with the negative electrode active material layer.

[0089] The end cap 23 is a component that covers the opening of the shell 21 to isolate the internal environment of the battery cell 20 from the external environment. The end cap 23 covers the opening of the shell 21, and the end cap 23 and the shell 21 together define a sealed space for accommodating the electrode assembly 22, the electrolyte and other components. The shape of the end cap 23 can be adapted to the shape of the shell 21. For example, the shell 21 is a rectangular parallelepiped structure, and the end cap 23 is a rectangular plate structure adapted to the shell 21. For another example, the shell 21 is a cylindrical structure, and the end cap 23 is a circular plate structure adapted to the shell 21. The material of the end cap 23 can also be a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. The material of the end cap 23 can be the same as or different from the material of the shell 21.

[0090] The end cap 23 may be provided with an electrode terminal, which is used to be electrically connected to the electrode assembly 22 to output the electrical energy of the battery cell 20. The electrode terminal may include a positive electrode terminal 231 and a negative electrode terminal 232, wherein the positive electrode terminal 231 is used to be electrically connected to the positive electrode tab 221, and the negative electrode terminal 232 is used to be electrically connected to the negative electrode tab 222. The positive electrode terminal 231 may be directly connected to the positive electrode tab 221 or indirectly connected, and the negative electrode terminal 232 may be directly connected to the negative electrode tab 222 or indirectly connected. Exemplarily, the positive electrode terminal 231 is electrically connected to the positive electrode tab 221 through a current collecting member 26, and the negative electrode terminal 232 is electrically connected to the negative electrode tab 222 through another current collecting member 26.

[0091] The insulating member 24 is a component that separates the housing 21 from the electrode assembly 22, and the insulating member 24 is used to achieve insulation isolation between the housing 21 and the electrode assembly 22. The insulating member 24 is an insulating material, and the insulating member 24 can be an insulating material such as plastic, rubber, etc. Exemplarily, the insulating member 24 is circumferentially coated on the outer periphery of the electrode assembly 22. It can be understood that when there are multiple electrode assemblies 22, the insulating member 24 is circumferentially coated on the outer periphery of the multiple electrode assemblies 22 as a whole.

[0092] The pressure relief device 25 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 25. The pressure relief device 25 may be a component provided on the end cover 23, or the housing 21 may serve as the pressure relief device 25, or the end cover 23 may serve as the pressure relief device 25. The specific structure of the pressure relief device 25 is described in detail below in conjunction with the accompanying drawings.

[0093] Please refer to Figure 4 and Figure 5 , Figure 4 An axonometric view of a pressure relief device 25 provided in some embodiments of the present application, Figure 5 for Figure 4The cross-sectional view of the pressure relief portion 251 is shown. The embodiment of the present application provides a pressure relief device 25, which includes a pressure relief portion 251 and a multi-stage notched groove 252. The pressure relief portion 251 has a first surface 2511 and a second surface 2512 relative to each other in the thickness direction Z thereof; the multi-stage notched groove 252 is sequentially arranged on the pressure relief portion 251 along the direction from the first surface 2511 to the second surface 2512. Among the two adjacent notched grooves 252 in the thickness direction Z, the first notched groove 252 away from the first surface 2511 is arranged on the bottom surface of the first notched groove 252 close to the first surface 2511.

[0094] The notched grooves 252 arranged in sequence along the thickness direction Z of the pressure relief portion 251 may be two-level, three-level, four-level, etc., and in the adjacent two-level notched grooves 252, the first-level notched groove 252 away from the first surface 2511 is arranged on the bottom surface of the first-level notched groove 252 close to the first surface 2511. The multi-level notched grooves 252 on the pressure relief portion 251 can be processed and formed in a variety of ways, such as stamping, milling, etc. Taking the stamping method to form the multi-level notched grooves 252 as an example, the multi-level notched grooves 252 can be stamped and formed in sequence on the pressure relief portion 251 along the direction from the first surface 2511 to the second surface 2512. The shapes of the notched grooves 252 can be various, such as straight line, arc, U-shaped, H-shaped, ring-shaped, rectangular, circular, etc. In the multi-level notched grooves 252 arranged in sequence along the thickness direction Z of the pressure relief portion 251, the shapes of the notched grooves 252 at each level can be the same or different. For example, in Figure 4 and Figure 5 In the embodiment, two levels of notched grooves 252 are provided on the pressure relief portion 251, and both of the two levels of notched grooves 252 are linear.

[0095] The first surface 2511 and the second surface 2512 of the pressure relief portion 251 are two surfaces opposite to each other in the thickness direction Z of the pressure relief portion 251 , and the distance between the first surface 2511 and the second surface 2512 is the thickness of the pressure relief portion 251 .

[0096] The pressure relief part 251 may be a component installed on the end cover 23, for example, the pressure relief part 251 is an explosion-proof plate installed on the end cover 23; the pressure relief part 251 may also serve as the end cover 23 as a whole; the pressure relief part 251 may be a part of the shell 21, for example, the pressure relief part 251 may be a wall portion of the shell 21 or a part of a wall portion.

[0097] In the pressure relief device 25, a multi-stage notched groove 252 is provided on the pressure relief portion 251, and the multi-stage notched groove 252 is sequentially arranged on the pressure relief portion 251 along the direction from the first surface 2511 to the second surface 2512 of the pressure relief portion 251, and the first-stage notched groove 252 away from the first surface 2511 is arranged on the bottom surface of the first-stage notched groove 252 close to the first surface 2511. The pressure relief device 25 with this structure adopts a multi-stage notched groove 252 structure, which can reduce the forming depth of each stage of the notched groove 252, thereby reducing the forming force exerted on the pressure relief portion 251 when forming each stage of the notched groove 252, reducing the risk of cracks in the pressure relief portion 251, and the pressure relief device 25 is not easy to fail due to cracks in the pressure relief portion 251 at the position where the notched groove 252 is set, thereby improving the long-term reliability of the pressure relief device 25.

[0098] When forming the multi-stage notched groove 252 on the pressure relief portion 251, the notched groove 252 can be formed step by step on the pressure relief portion 251 from the first surface 2511 to the second surface 2512. The forming depth of each stage of notched groove 252 is relatively shallow, so that the forming force on the pressure relief portion 251 is relatively small, which can reduce the risk of cracks in the pressure relief portion 251 and improve the flatness of the first surface 2511. In the process of processing the multi-stage notched groove 252 step by step from the first surface 2511 to the second surface 2512, the hardness of the position where the notched groove 252 is set on the pressure relief portion 251 increases with each processing of a stage of notched groove 252, thereby improving the hardness of the remaining part of the pressure relief portion 251 after the multi-stage notched groove 252 is set, so that the long-term reliability is better, the impact resistance is better, and the probability of damage by external impact is reduced.

[0099] In some embodiments, please refer to Figure 6 , Figure 6 An axonometric view of a pressure relief device 25 provided for some other embodiments of the present application; Figure 7 for Figure 6 A partial enlarged view of the pressure relief device 25 at A shown; Figure 8 for Figure 7 A partial view of the pressure relief portion 251 is shown; Fig. 9 for Figure 8 The BB cross-sectional view of the pressure relief portion 251 is shown. The multi-stage notched groove 252 includes at least one first-stage notched groove 252a, and the first-stage notched groove 252a includes a first groove section 2521, a second groove section 2522, and a third groove section 2523. The first groove section 2521 and the second groove section 2522 are arranged opposite to each other, and the first groove section 2521 and the second groove section 2522 both intersect with the third groove section 2523. The pressure relief portion 251 includes an opening area 2513, and the first groove section 2521, the second groove section 2522, and the third groove section 2523 are arranged along the edge of the opening area 2513, and the opening area 2513 is configured to be able to be opened with the first groove section 2521, the second groove section 2522, and the third groove section 2523 as boundaries.

[0100] Among the multi-level notched grooves 252 on the pressure relief portion 251, one level notched groove 252 may be the first level notched groove 252a, or multiple levels of adjacent notched grooves 252 may be the first level notched groove 252a. That is to say, one level of first level notched groove 252a may be provided on the pressure relief portion 251, or multiple levels of first level notched grooves 252a may be provided. If one level of first level notched groove 252a is provided on the pressure relief portion 251, it is understandable that one level of notched groove 252 among the multi-level notched grooves 252 is the first level notched groove 252a; if multiple levels of first level notched grooves 252a are provided on the pressure relief portion 251, it is understandable that multiple levels of notched grooves 252 among the multi-level notched grooves 252 are the first level notched grooves 252a. For example, if three levels of notched grooves 252 are provided on the pressure relief portion 251, two or three levels of notched grooves 252 may be the first level notched groove 252a. The first-level notch groove 252a includes multiple groove segments, wherein one groove segment is a first groove segment 2521 , another groove segment is a second groove segment 2522 , and another groove segment is a third groove segment 2523 .

[0101] The first slot section 2521, the second slot section 2522 and the third slot section 2523 may all be linear slots, the first slot section 2521 may be parallel to the second slot section 2522, and the first slot section 2521 and the second slot section 2522 may be perpendicular to the third slot section 2523. The position where the first slot section 2521 intersects with the third slot section 2523 may be located at one end of the third slot section 2523, or may be located at a position deviated from one end of the third slot section 2523, so that one end of the third slot section 2523 exceeds the first slot section 2521 along the extension direction of the third slot section 2523. The position where the second slot section 2522 intersects with the third slot section 2523 may be located at the other end of the third slot section 2523, or may be located at a position deviated from the other end of the third slot section 2523, so that the other end of the third slot section 2523 exceeds the second slot section 2522 along the extension direction of the third slot section 2523. The third slot section 2523 may be located at the ends of the first slot section 2521 and the second slot section 2522. For example, the first slot section 2521, the third slot section 2523 and the second slot section 2522 are sequentially connected to form a U shape. The third slot section 2523 may also be located in the middle of the first slot section 2521 and the second slot section 2522. For example, Figure 8 As shown, the first slot segment 2521, the second slot segment 2522 and the third slot segment 2523 form an H shape.

[0102] Along the thickness direction Z of the pressure relief portion 251, if multiple first-level notched grooves 252a are provided on the pressure relief portion 251, in two adjacent first-level notched grooves 252a, the first groove section 2521 in the first-level notched groove 252a away from the first surface 2511 is provided on the bottom surface of the first groove section 2521 in the first-level notched groove 252a close to the first surface 2511, and the two adjacent first groove sections 2521 extend in the same direction; the first-level notched groove 252a away from the first surface 2511 The second groove segment 2522 in 252a is arranged at the bottom surface of the second groove segment 2522 in the first-level first-level notch groove 252a close to the first surface 2511, and the two adjacent second groove segments 2522 have the same extension direction; the third groove segment 2523 in the first-level first-level notch groove 252a away from the first surface 2511 is arranged at the bottom surface of the third groove segment 2523 in the first-level first-level notch groove 252a close to the first surface 2511, and the two adjacent third groove segments 2523 have the same extension direction.

[0103] In this embodiment, the opening area 2513 can be opened with the first slot section 2521 , the second slot section 2522 and the third slot section 2523 as boundaries, thereby increasing the pressure relief area of ​​the pressure relief portion 251 and improving the pressure relief rate of the pressure relief portion 251 .

[0104] In some embodiments, please refer to Figure 8 The first-level notch groove 252a also includes a fourth groove segment 2524, which is located between the first groove segment 2521 and the second groove segment 2522, and the fourth groove segment 2524 intersects with the third groove segment 2523.

[0105] The first-stage notched groove 252a also includes a fourth groove segment 2524. It is understandable that the first-stage notched groove 252a also includes a groove segment called the fourth groove segment 2524. The first-stage notched groove 252a may include only the first groove segment 2521, the second groove segment 2522, the third groove segment 2523, and the fourth groove segment 2524, or may include other groove segments in addition to the first groove segment 2521, the second groove segment 2522, the third groove segment 2523, and the fourth groove segment 2524.

[0106] The fourth slot section 2524 may be a linear slot, and the fourth slot section 2524 may be parallel to the first slot section 2521 and the second slot section 2522, and perpendicular to the third slot section 2523. The fourth slot section 2524 intersects the third slot section 2523 at the midpoint of the fourth slot section 2524 and the midpoint of the third slot section 2523.

[0107] The length of the fourth slot segment 2524 is smaller than the length of the first slot segment 2521 and the second slot segment 2522 .

[0108] Along the thickness direction Z of the pressure relief portion 251, if multiple levels of first-level notched grooves 252a are set on the pressure relief portion 251, in two adjacent first-level notched grooves 252a, the fourth groove segment 2524 in the first-level notched groove 252a away from the first surface 2511 is set on the bottom surface of the fourth groove segment 2524 in the first-level notched groove 252a close to the first surface 2511, and the two adjacent fourth groove segments 2524 have the same extension direction.

[0109] In this embodiment, the fourth slot section 2524 located between the first slot section 2521 and the second slot section 2522 intersects with the third slot section 2523. The stress of the pressure relief portion 251 is more concentrated at the intersection of the third slot section 2523 and the fourth slot section 2524, and it is easier to rupture. Therefore, during the pressure relief process, the pressure relief portion 251 ruptures along the third slot section 2523 from the intersection of the third slot section 2523 and the fourth slot section 2524, and ruptures along the first slot section 2521 and the second slot section 2522 after the third slot section 2523 ruptures, so as to achieve rapid pressure relief.

[0110] In some embodiments, in the extension direction of the third slot segment 2523 , the distance from the intersection of the fourth slot segment 2524 and the third slot segment 2523 to the first slot segment 2521 is equal to the distance from the intersection of the fourth slot segment 2524 and the third slot segment 2523 to the second slot segment 2522 .

[0111] In the extension direction of the third slot segment 2523, the distance from the intersection position of the fourth slot segment 2524 and the third slot segment 2523 to the first slot segment 2521 is the length of the portion of the third slot segment 2523 between the fourth slot segment 2524 and the first slot segment 2521. In the extension direction of the third slot segment 2523, the distance from the intersection position of the fourth slot segment 2524 and the third slot segment 2523 to the second slot segment 2522 is the length of the portion of the third slot segment 2523 between the fourth slot segment 2524 and the second slot segment 2522. The fourth slot segment 2524 may be disposed at the midpoint of the third slot segment 2523 to achieve that the distance from the intersection position of the fourth slot segment 2524 and the third slot segment 2523 to the first slot segment 2521 is equal to the distance from the intersection position of the fourth slot segment 2524 and the third slot segment 2523 to the second slot segment 2522.

[0112] In this embodiment, since the distance from the intersection of the fourth slot section 2524 and the third slot section 2523 to the first slot section 2521 is equal to the distance from the intersection of the fourth slot section 2524 and the third slot section 2523 to the second slot section 2522, the pressure relief portion 251 can rupture along the third slot section 2523 at the intersection of the fourth slot section 2524 and the third slot section 2523, and then rupture synchronously along the first slot section 2521 and the second slot section 2522, so that the opening area 2513 can be opened more quickly.

[0113] In some embodiments, please refer to Figure 8 The first slot section 2521 , the second slot section 2522 and the third slot section 2523 define at least one opening area 2513 .

[0114] The opening area 2513 is defined by the first groove section 2521, the second groove section 2522 and the third groove section 2523, and the first-level notch groove 252a is not a closed structure. The opening area 2513 defined by the first groove section 2521, the second groove section 2522 and the third groove section 2523 can be one or two. For example, the first groove section 2521, the second groove section 2522 and the third groove section 2523 form an approximately U-shaped structure, and the opening area 2513 is one; for another example, the first groove section 2521, the second groove section 2522 and the third groove section 2523 form an approximately H-shaped structure, and the opening area 2513 is two.

[0115] In this embodiment, the opening area 2513 is defined by the first groove section 2521, the second groove section 2522 and the third groove section 2523. The opening area 2513 can be opened in a flipping manner. After the opening area 2513 is opened, it is always connected to other areas of the pressure relief portion 251 and is not easy to fall off, thereby reducing the risk of splashing after the opening area 2513 is opened.

[0116] In some embodiments, please refer to Figure 8 The first slot section 2521 , the second slot section 2522 and the third slot section 2523 define two opening areas 2513 , and the two opening areas 2513 are respectively located on both sides of the third slot section 2523 .

[0117] The first slot section 2521, the second slot section 2522 and the third slot section 2523 jointly define two opening areas 2513, and the first slot section 2521, the second slot section 2522 and the third slot section 2523 can form an approximately H-shaped structure. The third slot section 2523 and the first slot section 2521 can intersect at the midpoint of the first slot section 2521, and the third slot section 2523 and the second slot section 2522 can intersect at the midpoint of the second slot section 2522.

[0118] The two opening areas 2513 are respectively located on both sides of the third groove section 2523, so that the two opening areas 2513 are divided by the third groove section 2523. After the pressure relief portion 251 ruptures at the position of the third groove section 2523, the two opening areas 2513 will open in a split form along the first groove section 2521 and the second groove section 2522 to achieve pressure relief, thereby increasing the pressure relief area and effectively improving the pressure relief rate of the pressure relief portion 251.

[0119] It should be noted that, no matter whether the first-level notched groove 252a includes the fourth groove segment 2524 , the first groove segment 2521 , the second groove segment 2522 and the third groove segment 2523 can define two opening areas 2513 .

[0120] In some embodiments, please refer to Figure 8 and Fig. 9 A notch groove 253 is provided on the second surface 2512 and is located in the opening area 2513 . In the extending direction of the first groove section 2521 , there is a distance between the notch groove 253 and the third groove section 2523 .

[0121] The second surface 2512 is provided with a notch groove 253 located in the opening area 2513. It can be understood that the notch groove 253 is recessed from the second surface 2512 in the direction facing the first surface 2511. Of course, the notch groove 253 can be completely located in the opening area 2513, or the notch groove 253 can be partially located in the opening area 2513. The notch groove 253 can extend along the extension direction of the third groove section 2523, so that the notch groove 253 is parallel to the third groove section 2523.

[0122] In the embodiment where the first groove section 2521, the second groove section 2522 and the third groove section 2523 define an opening area 2513 together, the first surface 2511 may be provided with a corresponding notch groove 253. Figure 8 and Fig. 9 As shown, in the embodiment where the first slot segment 2521 , the second slot segment 2522 and the third slot segment 2523 jointly define two opening areas 2513 , the first surface 2511 may be provided with two notch slots 253 correspondingly, and one notch slot 253 is provided correspondingly to one opening area 2513 .

[0123] In this embodiment, the notch groove 253 is at a distance from the third groove section 2523 in the extension direction of the first groove section 2521, and the notch groove 253 is located in the opening area 2513, so that during the pressure relief process of the pressure relief part 251, a part of the pressure relief part 251 located in the opening area 2513 can flip around the position of the pressure relief part 251 in the notch groove 253 as the axis, making it easier to open the pressure relief.

[0124] In some embodiments, Fig. 9 As shown, the multi-stage score groove 252 includes a first-stage score groove 252a.

[0125] It is understandable that among the multiple levels of notched grooves 252, only one level of notched grooves 252 is a first level notched groove 252a. For example, two levels of notched grooves 252 are provided on the pressure relief portion 251, wherein the first level of notched grooves 252 is a first level notched groove 252a.

[0126] In this embodiment, there is only one first-level notch groove 252a in the multi-level notch groove 252, which is simple to form, improves production efficiency, and is conducive to reducing production costs.

[0127] In some embodiments, please refer to Figure 10-12 , Fig.10 An isometric view of a pressure relief device 25 provided in some further embodiments of the present application, Fig.11 for Fig.10 A partial enlarged view of the pressure relief device 25 at position C shown; Fig.12 for Fig.11 The DD cross-sectional view of the pressure relief portion 251 is shown. The multi-stage notched groove 252 includes a multi-stage first-stage notched groove 252a, and the multi-stage first-stage notched groove 252a is sequentially arranged from the first surface 2511 to the second surface 2512.

[0128] In two adjacent first-level scoring grooves 252 a , the first-level scoring groove 252 a far from the first surface 2511 is disposed on the bottom surface of the first-level scoring groove 252 a close to the first surface 2511 .

[0129] Two, three, four or five first-level notched grooves 252a may be provided on the pressure relief portion 251. The multi-level notched grooves 252 on the pressure relief portion 251 may all be first-level notched grooves 252a, or a portion of them may be first-level notched grooves 252a. Taking the three-level notched grooves 252 provided on the pressure relief portion 251 as an example, two of the notched grooves 252 may all be first-level notched grooves 252a, or three of the notched grooves 252 may all be first-level notched grooves 252a.

[0130] In this embodiment, the multiple first-level notched grooves 252a are sequentially arranged along the direction from the first surface 2511 to the second surface 2512, which can reduce the forming depth of each first-level notched groove 252a, thereby reducing the forming force on the pressure relief portion 251 when forming each first-level notched groove 252a, and reducing the risk of cracks in the pressure relief portion 251. In the process of processing the first-level notched grooves 252a step by step along the direction from the first surface 2511 to the second surface 2512, the hardness of the residual part of the pressure relief portion 251 at the position where the first-level notched groove 252a is set increases with each processing of the first-level notched groove 252a, thereby improving the hardness of the residual part of the pressure relief portion 251 after the multiple first-level notched grooves 252a are set, so that the long-term reliability is better, the impact resistance is better, and the probability of damage by external force impact is reduced.

[0131] In some embodiments, please refer to Fig.12 The outermost first-level notch groove 252a is disposed on the first surface 2511 .

[0132] The outermost first-level notch groove 252a is recessed from the first surface 2511 in a direction facing the second surface 2512. Fig.12 As shown, taking the pressure relief portion 251 with two levels of first-level notched grooves 252a as an example, the outermost first-level notched groove 252a is disposed on the first surface 2511, and the other first-level notched groove 252a is disposed on the bottom surface of the outermost first-level notched groove 252a.

[0133] In this embodiment, the outermost first-level notch groove 252a is set on the first surface 2511, and the outermost first-level notch groove 252a can be directly formed on the first surface 2511, which simplifies the structure of the pressure relief device 25 and reduces the production cost.

[0134] In some embodiments, the multi-stage score groove 252 includes two stages of first-stage score grooves 252a.

[0135] It is understandable that among the multi-stage notched grooves 252, only two stages of notched grooves 252 are first stage notched grooves 252a. If the number of notched grooves 252 on the pressure relief portion 251 is greater than two, only a portion of the notched grooves 252 among the multi-stage notched grooves 252 are first stage notched grooves 252a. Fig.12 As shown, if only two levels of notched grooves 252 are provided on the pressure relief portion 251, the two levels of notched grooves 252 are both first level notched grooves 252a.

[0136] In some embodiments, please refer to Figure 13-Figure 16 , Fig.13 An axonometric view of a pressure relief device 25 provided in some other embodiments of the present application; Fig.14 for Fig.13 A partial enlarged view of the pressure relief device 25 at position E shown; Fig.15 for Fig.14 A partial view of the pressure relief portion 251 is shown; Fig.16 for Fig.15 The multi-stage notched groove 252 further includes at least one second-stage notched groove 252b, which is arranged in sequence with at least one first-stage notched groove 252a along the direction from the first surface 2511 to the second surface 2512. The opening area 2513 is formed on the groove bottom wall 2525 of the first-stage second-stage notched groove 252b which is farthest from the first surface 2511.

[0137] The pressure relief portion 251 may be provided with one or more second-level notched grooves 252b. If the pressure relief portion 251 is provided with multiple second-level notched grooves 252b, the multiple second-level notched grooves 252b are sequentially provided on the pressure relief portion 251 along the direction from the first surface 2511 to the second surface 2512, and the bottom surface profile of each level of the second-level notched groove 252b is gradually reduced. Of course, the pressure relief portion 251 may be provided with one or more first-level notched grooves 252a.

[0138] At least one second-level notched groove 252b and at least one first-level notched groove 252a are sequentially arranged on the pressure relief portion 251 along the direction from the first surface 2511 to the second surface 2512. During molding, all second-level notched grooves 252b can be molded on the pressure relief portion 251 first, and then all notched grooves 252 can be molded along the direction from the first surface 2511 to the second surface 2512. It can be understood that the first-level first-level notched groove 252a closest to the first surface 2511 is arranged on the bottom surface of the first-level second-level notched groove 252b farthest from the first surface 2511. If only one second-level notched groove 252b is arranged in the pressure relief portion 251, the first-level second-level notched groove 252b is both the first-level second-level notched groove 252b closest to the first surface 2511 and the first-level second-level notched groove 252b farthest from the first surface 2511. Similarly, if only one first-level notch groove 252a is provided in the pressure relief portion 251 , the first-level notch groove 252a is both the first-level notch groove 252a closest to the first surface 2511 and the first-level notch groove 252a farthest from the first surface 2511 .

[0139] The groove bottom wall 2525 of the first-level second-level notched groove 252b farthest from the first surface 2511 is the portion of the pressure relief portion 251 below the bottom surface of the first-level second-level notched groove 252b farthest from the first surface 2511. After the pressure relief portion 251 forms the first-level second-level notched groove 252b farthest from the first surface 2511, the remaining portion of the pressure relief portion 251 where the first-level second-level notched groove 252b is set is the groove bottom wall 2525 of the first-level second-level notched groove 252b farthest from the first surface 2511. Fig.16 As shown, taking the example of setting a first-level second-level notch groove 252b on the pressure relief portion 251, the portion of the pressure relief portion 251 below the bottom surface of the second-level notch groove 252b is the groove bottom wall 2525 of the first-level second-level notch groove 252b farthest from the first surface 2511.

[0140] The opening area 2513 is formed on the bottom wall 2525 of the first-level second-level notch groove 252b farthest from the first surface 2511. The opening area 2513 is the part of the bottom wall 2525 of the first-level second-level notch groove 252b farthest from the first surface 2511 that can be opened with the first-level first-level notch groove 252a farthest from the first surface 2511 as the boundary during pressure release.

[0141] During molding, the second-level notched groove 252b can be firstly molded on the pressure relief portion 251, so that the pressure relief portion 251 is thinned as a whole in the area where the second-level notched groove 252b is set, and the hardness of the residual part in the area is improved; then, the first-level notched groove 252a is molded on the pressure relief portion 251, so that the hardness of the residual part of the pressure relief portion 251 at the position of the first-level notched groove 252a is further increased, so that the long-term reliability is better, the impact resistance is better, and the probability of damage by external impact is reduced. In addition, since the opening area 2513 is formed on the bottom wall 2525 of the first-level second-level notched groove 252b farthest from the first surface 2511, the second-level notched groove 252b can provide an escape space for the opening area 2513 during opening, and even if the first surface 2511 is blocked by obstacles, the opening area 2513 can still be opened to release pressure.

[0142] In some embodiments, please refer to Fig.16 The multi-level notch groove 252 includes a first-level second-level notch groove 252 b , and the second-level notch groove 252 b is disposed on the first surface 2511 .

[0143] Among the multiple-stage notched grooves 252, only one-stage notched groove 252 is a second-stage notched groove 252b. When the pressure relief portion 251 is provided with one-stage second-stage notched groove 252b, the pressure relief portion 251 may be provided with one-stage first-stage notched groove 252a or multiple-stage first-stage notched grooves 252a.

[0144] For example, Fig.16 As shown, taking the pressure relief portion 251 with three levels of notched grooves 252 as an example, the outermost first-level notched groove 252 is the second-level notched groove 252b, and the other two levels of notched grooves 252 are first-level notched grooves 252a. One first-level notched groove 252a is arranged on the bottom surface of the second-level notched groove 252b, and the other first-level notched groove 252a is arranged on the bottom surface of the first-level notched groove 252a.

[0145] In this embodiment, the pressure relief portion 251 is provided with a first-level and a second-level notch groove 252 b, which is simple to form, improves production efficiency, and reduces production costs.

[0146] In some embodiments, the multi-level notch groove 252 includes a multi-level second-level notch groove 252b, which is arranged in sequence from the first surface 2511 to the second surface 2512, and the outermost second-level notch groove 252b is arranged on the first surface 2511.

[0147] In two adjacent second-level notched grooves 252b, the first-level second-level notched groove 252b far from the first surface 2511 is arranged on the bottom surface of the first-level second-level notched groove 252b close to the first surface 2511. The first-level first-level notched groove 252a closest to the first surface 2511 is arranged on the bottom surface of the first-level second-level notched groove 252b farthest from the first surface 2511. In the case where the pressure relief portion 251 is provided with multiple levels of second-level notched grooves 252b, the pressure relief portion 251 may be provided with one level of first-level notched groove 252a or multiple levels of first-level notched grooves 252a.

[0148] In the multi-level notched groove 252, two, three, four or five levels of notched grooves 252 may be provided as the second level notched groove 252b. In other words, the pressure relief portion 251 may be provided with two, three, four or five levels of second level notched grooves 252b. The outermost level second level notched groove 252b is recessed from the first surface 2511 toward the direction close to the second surface 2512.

[0149] In this embodiment, the pressure relief portion 251 is provided with multiple levels of second-level notched grooves 252b, so that the forming depth of each level of the second-level notched grooves 252b can be relatively shallow, which can reduce the forming force on the pressure relief portion 251 when forming each level of the second-level notched grooves 252b, and reduce the risk of cracks in the pressure relief portion 251. When the multiple levels of second-level notched grooves 252b are processed step by step from the first surface 2511 to the second surface 2512, the hardness of the remaining part of the pressure relief portion 251 in the area where the second-level notched grooves 252b are provided increases with each processing of the second-level notched grooves 252b, so that the hardness of the remaining part of the pressure relief portion 251 in the area of ​​the first-level notched grooves 252a is further increased. In addition, in the multi-level second-level notched groove 252b, the outer second-level notched groove 252b has a larger profile size of the cross section (perpendicular to the thickness direction Z of the pressure relief portion 251), and the multi-level second-level notched groove 252b can provide more avoidance space for the opening of the opening area 2513.

[0150] In some embodiments, the second-level scoring groove 252b is a circular groove or a rectangular groove.

[0151] If the sink is a rectangular groove, the cross section of the side of the sink is rectangular. If the sink is a circular groove, the cross section of the side of the sink is circular. The cross section is perpendicular to the thickness direction Z of the pressure relief portion 251.

[0152] For example, in Figure 13-Figure 16 In the embodiment, the second-level notch groove 252b is a rectangular groove.

[0153] In this embodiment, the second-level notch groove 252 b is a circular groove or a rectangular groove. The second-level notch groove 252 b has a simple structure and is easy to form, and can provide more avoidance space for the opening of the opening area 2513 .

[0154] In some embodiments, each level of notch groove 252 includes at least one groove segment, and in two adjacent groove segments in the thickness direction Z, the maximum width of a groove segment away from the first surface 2511 is smaller than the minimum width of a groove segment close to the first surface 2511.

[0155] It can be understood that, in two adjacent groove sections in the thickness direction Z, the groove section away from the first surface 2511 is arranged on the bottom surface of the groove section close to the first surface 2511 .

[0156] The groove segment in the notched groove 252 may be one or more. If there is one groove segment in the notched groove 252, the groove segment is the notched groove 252. For example, if the notched groove 252 is a linear groove, a rectangular groove or a circular groove, there is one groove segment in the notched groove 252; for another example, if the notched groove 252 is H-shaped, there are multiple groove segments in the notched groove 252. For the second-level notched groove 252b, there is one groove segment in the second-level notched groove 252b; for the first-level notched groove 252a, there are multiple groove segments in the first-level notched groove 252a. For two adjacent levels of notched grooves 252, if there are multiple groove segments in both levels of notched grooves 252, the groove segments of a first-level notched groove 252 may correspond one-to-one to the groove segments of another level notched groove 252; if there is one groove segment in a first-level notched groove 252 close to the first surface 2511 and there are multiple groove segments in a first-level notched groove 252 away from the first surface 2511, multiple groove segments in a first-level notched groove 252 away from the first surface 2511 may be arranged on the bottom surface of one groove segment in a first-level notched groove 252 close to the first surface 2511.

[0157] In two adjacent groove segments in the thickness direction Z of the pressure relief portion 251, the maximum width of a groove segment away from the first surface 2511 is less than the minimum width of a groove segment close to the first surface 2511, that is, the groove segment width of the multi-stage notched groove 252 decreases step by step along the direction from the first surface 2511 to the second surface 2512. The maximum width of a groove segment away from the first surface 2511 does not limit the width of a groove segment away from the first surface 2511 of the two adjacent groove segments to be gradual. In the case where the width of a groove segment away from the first surface 2511 does not change along the thickness direction Z of the pressure relief portion 251, the width of a groove segment away from the first surface 2511 can also be called the maximum width. The minimum width of a groove segment close to the first surface 2511 does not limit the width of a groove segment close to the first surface 2511 among two adjacent groove segments to be gradual. When the width of a groove segment close to the first surface 2511 does not change along the thickness direction Z of the pressure relief portion 251, the width of the groove segment of the primary notch groove 252 close to the first surface 2511 can also be called the minimum width.

[0158] The maximum width of a slot segment far from the first surface 2511 and the minimum width of a slot segment close to the first surface 2511 are the dimensions of two adjacent slot segments along the thickness direction Z in the same direction.

[0159] Taking the adjacent two-stage notched groove 252 as the first-stage notched groove 252a as an example, it can be understood that the maximum width of the first groove segment 2521 (a groove segment away from the first surface 2511) of the first-stage notched groove 252a far from the first surface 2511 is smaller than the minimum width of the first groove segment 2521 (a groove segment close to the first surface 2511) of the first-stage notched groove 252a close to the first surface 2511; the second groove segment 2522 (a groove segment away from the first surface 2511) of the first-stage notched groove 252a far from the first surface 2511 is smaller than the minimum width of the first groove segment 2521 (a groove segment close to the first surface 2511) of the first-stage notched groove 252a close to the first surface 2511. 511) has a maximum width that is smaller than the minimum width of the second groove segment 2522 (a groove segment close to the first surface 2511) of the first-level first-level notch groove 252a close to the first surface 2511; the maximum width of the third groove segment 2523 (a groove segment close to the first surface 2511) of the first-level first-level notch groove 252a away from the first surface 2511 is smaller than the minimum width of the third groove segment 2523 (a groove segment close to the first surface 2511) of the first-level first-level notch groove 252a close to the first surface 2511.

[0160] Taking the two adjacent levels of notched grooves 252, namely the second level notched groove 252b and the first level notched groove 252a, as an example, it can be understood that the first level notched groove 252a is arranged on the bottom surface of the second level notched groove 252b, and the maximum width of the first groove segment 2521 of the first level notched groove 252a (a groove segment away from the first surface 2511) is smaller than the minimum width of the second level notched groove 252b (a groove segment close to the first surface 2511); the maximum width of the second groove segment 2522 of the first level notched groove 252a (a groove segment away from the first surface 2511) is smaller than the minimum width of the second level notched groove 252b (a groove segment close to the first surface 2511); the maximum width of the third groove segment 2523 of the first level notched groove 252a (a groove segment away from the first surface 2511) is smaller than the minimum width of the second level notched groove 252b (a groove segment close to the first surface 2511).

[0161] In this embodiment, the width of the groove segments of each level of notched groove 252 decreases step by step along the direction from the first surface 2511 to the second surface 2512. During molding, the groove segments of each level of notched groove 252 can be molded in sequence along the direction from the first surface 2511 to the second surface 2512, which facilitates the molding of the groove segments of each level of notched groove 252.

[0162] In some embodiments, please refer to Fig.17 , Fig.17 for Fig.16 The distance between the first surface 2511 and the second surface 2512 is H. 0 , the distance from the bottom surface of the primary notch groove 252 closest to the second surface 2512 to the second surface 2512 is H 1 , satisfying: H 1 / H 0 <0.2.

[0163] H 1 / H 0 It can be any value less than 0.2, for example, 0.05, 0.08, 0.1, 0.13, 0.15, 0.18, etc.

[0164] The distance between the first surface 2511 and the second surface 2512 is the thickness of the pressure relief portion 251. The distance from the bottom surface of the first-level notch groove 252 closest to the second surface 2512 to the second surface 2512 is the thickness of the portion between the bottom surface of the first-level notch groove 252 closest to the second surface 2512 and the second surface 2512, which is also the residual thickness of the pressure relief portion 251 in the area where the first-level notch groove 252 closest to the second surface 2512 is set. The first-level notch groove 252 closest to the second surface 2512 is also the first-level notch groove 252 farthest from the first surface 2511. In the embodiment where the pressure relief portion 251 is provided with only two levels of first-level notch grooves 252a, the first-level notch groove 252a farthest from the first surface 2511 is the first-level notch groove 252 closest to the second surface 2512. In the embodiment where the pressure relief portion 251 is provided with only one second-level notch groove 252b and one first-level notch groove 252a, the first-level notch groove 252a is the notch groove 252 closest to the second surface 2512. Fig.17 As shown, in the embodiment where the pressure relief portion 251 is provided with only one second-level notch groove 252b and two first-level notch grooves 252a, the first-level notch groove 252a far away from the second-level notch groove 252b is the first-level notch groove 252 closest to the second surface 2512.

[0165] The ratio of the distance from the bottom surface of the first-level notch groove 252 closest to the second surface 2512 to the second surface 2512 to the distance from the first surface 2511 to the second surface 2512 is less than 0.2, so that the residual thickness of the pressure relief portion 251 in the area where the first-level notch groove 252 closest to the second surface 2512 is set accounts for a relatively small proportion of the total thickness of the pressure relief portion 251, so that the portion between the bottom surface of the first-level notch groove 252 closest to the second surface 2512 and the second surface 2512 can rupture normally to achieve pressure relief.

[0166] In some embodiments, the distance from the bottom surface of the primary notch groove 252 closest to the second surface 2512 to the second surface 2512 is H. 1 , satisfying: H 1 <0.5mm.

[0167] H 1 It can be any value less than 0.5 mm, for example, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, etc.

[0168] In this embodiment, the distance from the bottom surface of the first-level notch groove 252 closest to the second surface 2512 to the second surface 2512 is less than 0.5 mm, so that the residual thickness of the pressure relief portion 251 in the area where the first-level notch groove 252 closest to the second surface 2512 is set is small, and it is easy to rupture and release pressure.

[0169] In some embodiments, the depth of the primary notch groove 252 disposed on the first surface 2511 is H 2 , satisfying: H 2 <1mm.

[0170] H 2 It can be any value less than 1 mm, for example, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, etc.

[0171] The depth of the primary notch groove 252 disposed on the first surface 2511 is the distance between the bottom surface of the notch groove 252 disposed on the first surface 2511 and the first surface 2511. Fig.17 As shown, taking the example that the pressure relief portion 251 is provided with only one second-level notch groove 252 b and two first-level notch grooves 252 a , the second-level notch groove 252 b is the notch groove 252 provided on the first surface 2511 .

[0172] In this embodiment, the depth of the first-level notch groove 252 arranged on the first surface 2511 is less than 1 mm, so that the depth of the outermost first-level notch groove 252 of the pressure relief portion 251 is smaller, thereby reducing the forming force exerted on the pressure relief portion 251 at this level of notch groove 252 during the forming process, thereby reducing the risk of cracks in the pressure relief portion 251.

[0173] In some embodiments, the depth of each level of the notch groove 252 between the first level notch groove 252 closest to the second surface 2512 and the first level notch groove 252 disposed on the first surface 2511 is H. 3 , satisfying: H 3 <1.5mm.

[0174] H 3 It can be any value less than 1.5 mm, for example, 0.2 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, etc.

[0175] It can be understood that the pressure relief portion 251 is provided with at least three levels of notched grooves 252 .

[0176] In this embodiment, the depth of each level of notch groove 252 between the first-level notch groove 252 closest to the second surface 2512 and the first-level notch groove 252 arranged on the first surface 2511 is less than 1.5 mm, so that the depth of each level of notch groove 252 on the pressure relief portion 251 except for the first-level notch groove 252 closest to the second surface 2512 and the first-level notch groove 252 arranged on the first surface 2511 is smaller, thereby reducing the molding force exerted on the pressure relief portion 251 during the molding process and reducing the risk of cracks in the pressure relief portion 251.

[0177] In some embodiments, only one primary score groove 252 is disposed between the primary score groove 252 closest to the second surface 2512 and the primary score groove 252 disposed on the first surface 2511 .

[0178] For example, Fig.17 As shown, taking the example that the pressure relief portion 251 is provided with only one-level second-level notched groove 252b and two-level first-level notched groove 252a, the first-level notched groove 252a far away from the second-level notched groove 252b is the first-level notched groove 252 closest to the second surface 2512, the second-level notched groove 252b is the first-level notched groove 252 arranged on the first surface 2511, and the other first-level notched groove 252a is the first-level notched groove 252 closest to the second surface 2512 and the first-level notched groove 252 arranged on the first surface 2511.

[0179] In this embodiment, three levels of notched grooves 252 are provided on the pressure relief portion 251 , which has a simple structure and can reduce the forming depth of each level of notched grooves 252 , thereby reducing the risk of cracks in the pressure relief portion 251 .

[0180] In some embodiments, please refer to Figure 4 , Figure 6 , Fig.10 and Fig.13 A accommodating space is formed inside the pressure relief device 25 . The pressure relief device 25 has a plurality of walls defining the accommodating space. The accommodating space is used to accommodate the electrode assembly 22 . A pressure relief portion 251 is formed on at least one of the plurality of walls.

[0181] Among the multiple wall portions of the pressure relief device 25, one wall portion may be the pressure relief portion 251, or multiple wall portions may be the pressure relief portion 251. If multiple wall portions are the pressure relief portions 251, the pressure relief device 25 has multiple pressure relief portions 251 accordingly. The first surface 2511 of the pressure relief portion 251 may be the outer surface of the wall portion, or the inner surface of the wall portion. The outer surface of the wall portion is the surface of the wall portion facing away from the electrode assembly 22, and the inner surface of the wall portion is the surface of the wall portion facing the electrode assembly 22. In this embodiment, the pressure relief device 25 serves as the shell 21 of the battery cell 20.

[0182] In this embodiment, the pressure relief device 25 has both a function of accommodating the electrode assembly 22 and a pressure relief function.

[0183] In some embodiments, the multiple wall portions include a peripheral wall 254 and a bottom wall 255. The peripheral wall 254 is arranged around the edge of the bottom wall 255. The peripheral wall 254 and the bottom wall 255 together define a accommodating space. An opening is formed at the end opposite to the bottom wall 255. The bottom wall 255 is formed with a pressure relief portion 251.

[0184] The peripheral wall 254 is disposed around the edge of the bottom wall 255 , so that the pressure relief device 25 forms an opening at an end opposite to the bottom wall 255 , and the end cover 23 is used to cover the opening.

[0185] In the embodiment where the pressure relief device 25 is a cylinder, the pressure relief device 25 may have two walls, one wall being a bottom wall 255 and the other being a cylindrical peripheral wall 254. Figure 4 , Figure 6 , Fig.10 and Fig.13 As shown, in the embodiment in which the pressure relief device 25 is a rectangular parallelepiped, the pressure relief device 25 may have five wall portions, namely a bottom wall 255 and four side walls, and the four side walls are connected end to end in sequence to form a peripheral wall 254.

[0186] In this embodiment, the bottom wall 255 of the pressure relief device 25 has a pressure relief function, which is convenient for releasing the pressure inside the accommodating space.

[0187] In some embodiments, the peripheral wall 254 and the bottom wall 255 are an integrally formed structure.

[0188] The peripheral wall 254 and the bottom wall 255 can be integrally formed together, for example, by stamping, casting, etc.

[0189] In this embodiment, since the bottom wall 255 is formed with a pressure relief portion 251, the peripheral wall 254 and the bottom wall 255 are an integrally formed structure, so that the peripheral wall 254 and the bottom wall 255 with a pressure relief function have good firmness. This integrated design can simplify the molding process and reduce production costs.

[0190] In some embodiments, the first surface 2511 is the outer surface of the bottom wall 255. The multi-stage notched grooves 252 are arranged sequentially from the outer surface of the bottom wall 255 to the inner surface of the bottom wall 255. The notched grooves 252 can be machined on the outer side of the bottom wall 255 to facilitate machining the notched grooves 252 on the bottom wall 255.

[0191] In some embodiments, please refer to Fig.18 and Fig.19 , Fig.18 This is an axonometric view of a pressure relief device 25 provided in another embodiment of the present application. Fig.19 for Fig.18 The pressure relief device 25 is shown in a partially enlarged view at H. The pressure relief portion 251 is an end cover 23, and the end cover 23 is used to cover the opening of the housing 21.

[0192] The first surface 2511 may be the outer surface of the end cover 23, and the second surface 2512 may be the inner surface of the end cover 23; or the first surface 2511 may be the inner surface of the end cover 23, and the second surface 2512 may be the outer surface of the end cover 23. The outer surface of the end cover 23 is the surface of the end cover 23 facing away from the housing 21, and the inner surface of the end cover 23 is the surface of the end cover 23 facing the housing 21.

[0193] For example, in Fig.18 In the embodiment, three levels of notched grooves 252 are provided on the end cover 23, namely, a first-level second-level notched groove 252b and two-level first-level notched grooves 252a.

[0194] In this embodiment, the end cover 23 has a pressure relief function. A pressure relief structure is formed by providing a notched groove 252 on the end cover 23. The pressure relief structure has better stability and good long-term reliability.

[0195] In some embodiments, Fig.18 As shown, the first surface 2511 is the surface of the end cover 23 facing away from the housing 21. It can be understood that the first surface 2511 is the outer surface of the end cover 23, and the outermost primary notch groove 252 is provided on the outer surface of the end cover 23.

[0196] An embodiment of the present application provides a battery cell 20, comprising a pressure relief device 25 provided in any one of the above embodiments.

[0197] In a third aspect, an embodiment of the present application provides a battery 100, comprising a battery cell 20 provided in any one of the above embodiments.

[0198] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising a battery 100 provided in any one of the above embodiments.

[0199] The power-consuming device may be any of the above-mentioned devices using the battery 100 .

[0200] Please refer to Figure 13-Figure 16 The embodiment of the present application also provides a shell 21, which is a rectangular parallelepiped structure. The shell 21 includes multiple wall portions, which together define a storage space for accommodating the electrode assembly 22. The shell 21 has an opening, and a three-level notch groove 252 is provided on the wall portion of the shell 21 opposite to the opening. The three-level notch groove 252 is respectively a first-level second-level notch groove 252b and a two-level first-level notch groove 252a, and the second-level notch groove 252b is provided on the outer surface of the wall portion. The shell 21 of this structure integrates the pressure relief function and the storage function. The three-level notch groove 252 structure can reduce the forming force on the shell 21 when forming each level of notch groove 252, reduce the risk of cracks in the shell 21, and improve the long-term reliability of the shell 21.

[0201] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0202] The above embodiments are only used to illustrate the technical solution of the present application and are not used 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 pressure relief device, comprising: The pressure relief portion has a first surface and a second surface opposite to each other in the thickness direction thereof; A multi-level scoring groove is sequentially arranged on the pressure relief portion along the direction from the first surface to the second surface, and in two adjacent levels of the scoring grooves in the thickness direction, the first level of the scoring groove away from the first surface is arranged on the bottom surface of the first level of the scoring groove close to the first surface; The distance between the first surface and the second surface is H0, and the distance from the bottom surface of the first-level notch groove closest to the second surface to the second surface is H1, satisfying: H1 / H0<0.2, H1<0.5mm.

2. The pressure relief device according to claim 1, wherein: The multi-level notched groove includes at least one first-level notched groove, the first-level notched groove includes a first groove segment, a second groove segment and a third groove segment, the first groove segment and the second groove segment are arranged opposite to each other, and the first groove segment and the second groove segment both intersect with the third groove segment; The pressure relief portion includes an opening area, the first slot segment, the second slot segment and the third slot segment are arranged along the edge of the opening area, and the opening area is configured to be able to open with the first slot segment, the second slot segment and the third slot segment as boundaries.

3. The pressure relief device according to claim 2, wherein: The first-level notch groove further includes a fourth groove segment, wherein the fourth groove segment is located between the first groove segment and the second groove segment, and the fourth groove segment intersects with the third groove segment.

4. The pressure relief device according to claim 3, wherein: In the extension direction of the third slot segment, the distance from the intersection position of the fourth slot segment and the third slot segment to the first slot segment is equal to the distance from the intersection position of the fourth slot segment and the third slot segment to the second slot segment.

5. The pressure relief device according to claim 2, wherein: The first slot segment, the second slot segment and the third slot segment define at least one opening area.

6. The pressure relief device according to claim 2, wherein: The first slot section, the second slot section and the third slot section define two opening areas, and the two opening areas are respectively located on both sides of the third slot section.

7. The pressure relief device according to claim 2, wherein: The second surface is provided with a notch groove located in the opening area, and in the extending direction of the first groove segment, there is a distance between the notch groove and the third groove segment.

8. The pressure relief device according to claim 2, wherein: The multi-level scoring groove includes a first-level scoring groove.

9. The pressure relief device according to claim 2, wherein: The multi-level scoring grooves include multiple levels of the first-level scoring grooves, and the multiple levels of the first-level scoring grooves are arranged in sequence along the direction from the first surface to the second surface.

10. The pressure relief device according to claim 9, wherein: The outermost first-level notch groove is arranged on the first surface.

11. The pressure relief device according to claim 9, wherein: The multi-stage scoring groove includes two stages of the first-stage scoring groove.

12. The pressure relief device according to claim 2, wherein: The multi-level scoring grooves further include at least one second-level scoring groove, and the at least one second-level scoring groove and the at least one first-level scoring groove are arranged in sequence along a direction from the first surface to the second surface; Wherein, the opening area is formed on the bottom wall of the first-level and second-level notch grooves farthest from the first surface.

13. The pressure relief device according to claim 12, wherein: The multi-level scoring groove includes a first-level second-level scoring groove, and the second-level scoring groove is arranged on the first surface.

14. The pressure relief device according to claim 12, wherein: The multi-level notch grooves include a plurality of second-level notch grooves, the plurality of second-level notch grooves are sequentially arranged from the first surface to the second surface, and the outermost second-level notch groove is arranged on the first surface.

15. The pressure relief device according to claim 12, wherein: The second-level notch groove is a circular groove or a rectangular groove.

16. The pressure relief device according to any one of claims 1 to 15, wherein: Each level of the notched groove includes at least one groove segment. Among two adjacent groove segments in the thickness direction, the maximum width of the groove segment far from the first surface is smaller than the minimum width of the groove segment close to the first surface.

17. The pressure relief device according to any one of claims 1 to 15, wherein: The depth of the first-level notch groove arranged on the first surface is H2, satisfying: H2<1mm.

18. The pressure relief device according to any one of claims 1 to 15, wherein: The depth of each level of the scoring groove between the level one scoring groove closest to the second surface and the level one scoring groove arranged on the first surface is H3, satisfying: H3<1.5mm.

19. The pressure relief device according to claim 18, wherein: Only one first-level notch groove is arranged between the first-level notch groove closest to the second surface and the first-level notch groove arranged on the first surface.

20. The pressure relief device according to any one of claims 1 to 15, wherein: An accommodating space is formed inside the pressure relief device. The pressure relief device has a plurality of walls defining the accommodating space. The accommodating space is used to accommodate the electrode assembly. The pressure relief portion is formed on at least one of the plurality of walls.

21. The pressure relief device according to claim 20, wherein: The multiple wall portions include a peripheral wall and a bottom wall. The peripheral wall is arranged around the edge of the bottom wall. The peripheral wall and the bottom wall together define the accommodating space. An opening is formed at one end of the peripheral wall opposite to the bottom wall. The bottom wall is formed with the pressure relief portion.

22. The pressure relief device according to claim 21, wherein: The peripheral wall and the bottom wall are an integrally formed structure.

23. The pressure relief device according to claim 21, wherein: The first surface is an outer surface of the bottom wall.

24. The pressure relief device according to any one of claims 1 to 15, wherein: The pressure relief portion is an end cover, and the end cover is used to cover the opening of the shell.

25. The pressure relief device according to claim 24, wherein: The first surface is a surface of the end cover facing away from the housing.

26. A battery cell comprising the pressure relief device according to any one of claims 1 to 25.

27. A battery comprising the battery cell according to claim 26.

28. An electrical device comprising the battery according to claim 27.

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