Battery Cell

Abstract

The embodiment of the present application relates to a battery cell, comprising: a shell having an opening; a cover plate covering the opening, the cover plate being welded to the shell to form a weld; a pressure relief device arranged on the cover plate, the pressure relief device being provided with a weak area, the weak area being configured to be destroyed to release the internal pressure when the internal pressure or temperature of the battery cell reaches a threshold, wherein the minimum distance between the edge of the weak area and the weld is greater than or equal to 3 mm. The battery cell provided by the embodiment of the present application can ensure that the explosion-proof valve explodes and releases pressure in time when an abnormality occurs in the battery cell or the internal temperature and pressure rise sharply.

Description

Technical Field

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

[0002] Lithium-ion battery is a high-performance secondary battery with advantages such as high operating voltage, high energy density, small size, large capacity, long cycle life, and no memory effect. It is widely used in consumer electronics, power batteries, etc. In the manufacturing process of lithium-ion batteries, the battery cell is usually sealed in a battery cell casing and cover plate that are welded together.

[0003] In order to prevent the explosion caused by thermal runaway inside the battery, an explosion-proof valve is usually installed on the cover plate when producing battery packs. When an abnormality occurs in the battery cell and thermal runaway occurs inside the battery, causing the temperature and pressure to rise sharply, the gas generated in the battery cell will break through the notched area of ​​the explosion-proof valve and cause the explosion-proof valve to burst open, thereby achieving the purpose of pressure relief. Therefore, when an abnormality occurs in the battery cell and the internal temperature and pressure rise sharply, how to ensure that the explosion-proof valve bursts open and releases pressure in time has become a technical issue of great concern in the battery manufacturing field. Summary of the invention

[0004] In view of the problems existing in the background technology, the present application provides a battery cell, which can ensure that the explosion-proof valve explodes and releases pressure in time when an abnormality occurs in the battery cell and the internal temperature and pressure rise sharply.

[0005] An embodiment of the present application provides a battery cell, comprising: a shell having an opening; a cover plate covering the opening, the cover plate being welded to the shell to form a weld; a pressure relief device arranged on the cover plate, the pressure relief device being provided with a weak area, the weak area being configured to be destroyed to release the internal pressure when the internal pressure or temperature of the battery cell reaches a threshold value, wherein the minimum distance between the edge of the weak area and the weld is greater than or equal to 3 mm.

[0006] Compared with the prior art, the battery cell provided in the present application sets the edge of the weak zone of the pressure relief device to be at least 3 mm away from the weld, so that when the cover plate is welded to the shell to form a weld, the problem of the edge of the weak zone being too close to the weld, which causes the bursting pressure to increase after the welding is completed, can be avoided as much as possible, and the variation range of the bursting pressure of the weak zone before and after the cover plate welding is reduced. Therefore, the bursting force of the weak zone of the pressure relief device of the welded battery cell can maintain the original design pressure threshold before assembly as much as possible, ensuring that when the battery cell is abnormal and the internal temperature and pressure rise sharply, the weak zone of the pressure relief device can burst and release pressure in time when the design pressure threshold is reached.

[0007] Optionally, there are multiple pressure relief devices. Since the distance between the edge of the weak zone set on the cover plate and the weld is more than 3 mm, the area of ​​the weak zone cannot be designed to be larger, which limits the diameter of the pressure relief port after the weak zone explodes, affecting the pressure relief speed to a certain extent. Therefore, after setting up multiple pressure relief devices as described above, the number of pressure relief ports is increased, which makes up for the defect that the diameter of the pressure relief port cannot be enlarged and the pressure relief speed is affected due to the inability to design a larger area of ​​a single weak zone, and effectively improves the pressure relief capacity.

[0008] Optionally, the weak areas of at least two of the pressure relief devices have different areas. Different weak areas have different areas, so that the diameters of the pressure relief ports after the explosion of each weak area are different. In this way, different explosion pressures can be designed for weak areas of different areas. In the process of gradual increase in the internal pressure of the battery, one or part of the weak areas with smaller explosion pressure will be exploded first to release the pressure. When the internal pressure of the battery cannot be effectively released and continues to increase, one or part of the weak areas with larger explosion pressure will be exploded to increase the pressure relief capacity, so as to realize the explosion of different numbers of pressure relief devices at different pressure thresholds and achieve a gradient explosion effect.

[0009] Optionally, the minimum distance between the edge of the weak zone of each of the pressure relief devices and the weld is the same. It has been found through experiments that the (minimum) distance between the edge of the weak zone and the weld determines the pressure change amplitude of the bursting pressure of the weak zone before and after the cover plate is welded. The minimum distance between the edge of the weak zone of each of the pressure relief devices and the weld is the same. Under the premise of minimizing the influence of the weld on the bursting pressure, it can be ensured that the pressure change amplitude of the weak zone of each of the pressure relief devices is also the same, so as to achieve an explosion-proof effect closer to the design parameters.

[0010] Optionally, the minimum distance between the weak areas of any two adjacent pressure relief devices is greater than or equal to 3 mm. Keeping the minimum distance between the weak areas of adjacent pressure relief devices above 3 mm can minimize the deviation between the actual bursting pressure and the design threshold caused by the weak areas being too close to each other.

[0011] Optionally, it also includes a positive terminal and a negative terminal arranged on the cover plate, and the plurality of pressure relief devices are located between the positive terminal and the negative terminal.

[0012] Optionally, it further includes a liquid injection port disposed on the cover plate and located between the positive terminal and the negative terminal, and a plurality of the pressure relief devices are disposed on both sides of the liquid injection port. The pressure relief devices are disposed on both sides of the liquid injection port to disperse the positions of the pressure relief devices as much as possible, ensure that the pressure relief devices are as far away from other surrounding component structures as possible, and avoid deviations between the actual bursting pressure and the design threshold as much as possible.

[0013] Optionally, a liquid injection port is provided on the cover plate and located between the positive terminal and the negative terminal, and a plurality of the pressure relief devices are provided on the same side of the liquid injection port.

[0014] Optionally, there are two pressure relief devices, and the ratio of lower limits of bursting pressures of the weak zones of the two pressure relief devices is between 1.2-1.5.

[0015] Optionally, the weak area size of each of the pressure relief devices has a predetermined value, at least some of the weak area sizes of the pressure relief devices have a first predetermined value, and at least some of the weak area sizes of the pressure relief devices have a second predetermined value. The weak area size of each of the pressure relief devices is designed to be a predetermined value, and according to the actual pressure relief requirements of different battery products, pressure relief devices of various sizes can be selected and combined, and then arranged on the cover plate to enable the battery cell to have the desired pressure relief capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of the exploded structure of a battery cell provided in the first embodiment of the present application;

[0017] Figure 2 yes Figure 1 A schematic side view of the cover structure of the battery cell shown;

[0018] Figure 3 It is a graph showing the strength of the weak zone as a function of the distance between the edge and the weld;

[0019] Figure 4 This is a schematic diagram of another cover structure of a battery cell provided in the first embodiment of the present application;

[0020] Figure 5 is a schematic diagram of the cover structure of a battery cell provided in the second embodiment of the present application;

[0021] Figure 6 This is a schematic diagram of another cover structure of a battery cell provided in the second embodiment of the present application;

[0022] In the drawings, the drawings are not drawn to scale.

[0023] Marking Description:

[0024] 100 - battery cell; 11 - housing; 12 - cover plate; 13 - pressure relief device; 14 - positive terminal; 15 - negative terminal; 16 - liquid filling port; 110 - opening; 130 - weak area. DETAILED DESCRIPTION

[0025] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description, and the specific implementation of the present application should not be construed as any limitation, and the various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein 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 figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0027] In the description of the present application, it should be noted that, unless otherwise specified, "multiple" means more than two (including two); the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating the orientation or positional relationship are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.

[0028] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations 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. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] The term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0030] 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.

[0031] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of this application. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0032] At present, the manufacturing of lithium-ion batteries used in consumer electronics or power batteries usually includes process flows such as electrode sheet production, battery cell assembly, battery cell shelling, cover plate packaging, drying and liquid injection, and chemical componentization. After the above process flows, the assembled battery cells will be sealed in the battery cell shell and cover plate that are welded together.

[0033] In order to prevent the explosion caused by thermal runaway inside the battery, an explosion-proof valve is usually set on the cover plate when producing battery packs. The explosion-proof valve is usually an aluminum sheet with notches. The pressure boundary is greater than the gas production pressure during the battery life cycle and less than the weld strength of the cover plate and the battery cell shell. When the battery cell is abnormal and the thermal runaway inside the battery causes the temperature and pressure to rise sharply, the gas generated in the battery cell will break through the notched area of ​​the explosion-proof valve and cause the explosion-proof valve to explode, thereby achieving the purpose of pressure relief. The inventors noticed that in the existing battery cell manufacturing process, when the cover plate with an explosion-proof valve is welded to the shell, the weld between the cover plate and the shell will cause the explosion force of the notched area of ​​the explosion-proof valve to increase significantly, so that the cover plate originally designed to have a predetermined explosion force increases significantly after being welded to the shell. When the temperature and pressure inside the battery rise sharply and the pressure rises to the predetermined explosion force, the notched area of ​​the explosion-proof valve cannot explode in time, so there is a risk of battery explosion.

[0034] Based on the above considerations, in order to avoid the risk of battery explosion caused by the weld affecting the bursting force, the applicant has provided a battery cell after in-depth research, including: a shell having an opening; a cover plate covering the opening, the cover plate and the shell being welded to form a weld; a pressure relief device arranged on the cover plate, the pressure relief device being provided with a weak area, the weak area being configured to be destroyed to release the internal pressure when the internal pressure or temperature of the battery cell reaches a threshold, wherein the minimum distance between the edge of the weak area and the weld is greater than or equal to 3 mm. In this battery cell, the edge of the weak area of ​​the pressure relief device is set to be at least 3 mm away from the weld, so that when the cover plate is welded to the shell to form a weld, the problem of the edge of the weak area being too close to the weld causing the bursting pressure to increase after the welding is completed can be avoided as much as possible, and the change range of the bursting pressure of the weak area before and after the cover plate is welded can be reduced, so that the bursting force of the weak area of ​​the pressure relief device of the welded battery cell can be kept as much as possible at the original design pressure threshold before assembly, ensuring that when the battery cell is abnormal, the internal temperature and pressure rise sharply, the weak area of ​​the pressure relief device can burst and release pressure in time when reaching the design pressure threshold.

[0035] The battery cell disclosed in the embodiment of the present application can be used in, but not limited to, electrical devices such as vehicles, ships or aircraft. The electrical devices using the battery cell can also be, but not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and aircraft can include airplanes, rockets, space shuttles, and spacecraft, etc. In this way, it is beneficial to ensure that the explosion-proof valve of the electrical device explodes in time and the pressure is relieved when the battery core is abnormal and the internal temperature and pressure rise sharply, thereby improving the safety of the battery.

[0036] The implementation details of the battery cell housing provided in the embodiment of the present application are described below. The following content is only provided for the convenience of understanding and is not necessary for implementing the present solution.

[0037] See also Figure 1 and Figure 2 The first embodiment of the present application provides a battery cell 100 , including a housing 11 , a cover plate 12 , a pressure relief device 13 , a positive terminal 14 , a negative terminal 15 , and a liquid injection port 16 .

[0038] The shell 11 plays the role of fixing and sealing the internal electrochemical system, and its interior is used to set the battery cell and electrolyte, which can be a steel shell, an aluminum alloy shell, etc. In the present embodiment, the shell 11 has an internal accommodating space and an opening 110 connected to the internal accommodating space, which is used to accommodate the battery cell and the electrolyte. In the battery manufacturing process, the battery cell will first be placed in the accommodating space of the shell 11, and then the shell 11 will be welded and packaged using the cover plate 12, and then the process operations such as liquid injection will be performed. The shape of the shell 11 can be cylindrical (circular in cross section), square cylindrical (rectangular in cross section) or other shapes. In the present embodiment, the shell 11 is square cylindrical. Specifically, in the preparation process of the battery cell 100, the material of the shell 11 can be steel, aluminum, aluminum-plastic film, etc., which can be determined according to different battery design requirements.

[0039] The cover plate 12 is used to cover the opening 110 and to be welded with the shell 11 to form a weld, which surrounds the edge of the cover plate 12 (i.e., the outer contour of the cover plate 12) and closes the edge of the cover plate 12 and the opening 110 to seal the battery cell and the electrolyte within the shell 11 to prevent moisture intrusion and electrolyte leakage.

[0040] The pressure relief device 13 is arranged on the cover plate 12. The pressure relief device 13 is provided with a weak area 130, and the weak area 130 is configured to be destroyed to release the internal pressure when the internal pressure or temperature of the battery cell 100 reaches a threshold value, wherein the minimum distance d between the edge of the weak area and the weld is greater than or equal to 3 mm. Specifically, in this embodiment, the pressure relief device 13 is an explosion-proof valve, which is generally runway-shaped, and the weak area 130 on the surface of the explosion-proof valve is a notch, and the pressure boundary of the weak area 130 is greater than the gas production pressure of the battery cell 100 during its life cycle, and is less than the weld strength of the cover plate 12 and the shell 11. In this way, when an abnormality occurs in the battery cell and the thermal runaway inside the shell 11 causes a sharp increase in temperature and pressure, the gas generated in the battery cell will break through the notch area to make the explosion-proof valve explode, thereby achieving the purpose of pressure relief.

[0041] The positive terminal 14 and the negative terminal 15 are disposed on the cover plate 12 , and the pressure relief device 13 is located between the positive terminal 14 and the negative terminal 15 .

[0042] The liquid injection port 16 is disposed on the cover plate 12 and is located between the positive terminal 14 and the pressure relief device 13 , and is used to inject electrolyte into the housing 11 sealed by the cover plate 12 .

[0043] The inventors have found that in the conventional battery cell manufacturing process, when the cover plate 12 provided with the explosion-proof valve is welded to the shell 11, the weld between the cover plate 12 and the shell 11 will cause a significant increase in the blasting force of the notched area of ​​the explosion-proof valve. When the distance between the weld and the notched area increases, the increase in the blasting force of the notched area of ​​the explosion-proof valve will decrease. Figure 3As shown in the curve. Therefore, in this embodiment, the edge of the weak area 130 is set to be at least 3 mm away from the weld. The relatively far distance between the two makes the weld between the cover plate 12 and the shell 11 have little effect on the bursting force of the weak area 130 when the cover plate 12 is welded to the shell 11, so that the bursting force of the cover plate 12 before and after being welded to the shell 11 is almost unchanged, thereby ensuring the consistency of the bursting force of the weak area 13 before and after welding, that is, the bursting force of the weak area 130 can try to maintain the original design pressure threshold before assembly, ensuring that when the battery cell is abnormal and the temperature and pressure inside the shell 11 rise sharply, the weak area 130 of the pressure relief device 13 can burst and release pressure in time when it reaches the design pressure threshold.

[0044] In the actual production process, in order to facilitate procurement, the cover plate 12 of the battery cell 100 usually has a fixed size. However, under the design concept of the present application, increasing the minimum distance between the edge of the weak zone 130 and the weld will occupy the size of the setting area of ​​the pressure relief device 13, thereby resulting in the area of ​​the weak zone 130 cannot be designed to be larger, which to a certain extent affects the pressure relief speed after the weak zone 130 explodes and cannot meet the greater pressure relief requirements of some large-capacity battery cells.

[0045] Therefore, in the examples of this application, see Figure 4 , a plurality of pressure relief devices 13 may be provided. After the plurality of pressure relief devices 13 are provided, the weak area 130 of each pressure relief device 13 may become a pressure relief port after explosion. Thus, by increasing the number of pressure relief ports, the defect that the diameter of the pressure relief port cannot be increased and the pressure relief speed is affected due to the inability to design a larger area of ​​a single weak area 130 can be compensated, thereby effectively improving the pressure relief capacity.

[0046] It should be noted that, in the direction from one side to the other side of the cover plate 12, the positive terminal 14, the liquid injection port 16, the two pressure relief devices 13 and the negative terminal 15 are arranged in sequence, and the long axis direction of the runway-type pressure relief device 13 is consistent with the arrangement direction. However, it can be understood that as long as the edge of the weak area 130 is at least 3 mm away from the weld, the long axis direction of the runway-type pressure relief device 13 can also be along other directions, for example, the long axis direction of the runway-type pressure relief device 13 is perpendicular to the arrangement direction. Of course, when the number of pressure relief devices 13 is single, its long axis direction can also be flexibly adjusted on the premise of ensuring that the edge of the weak area 130 is at least 3 mm away from the weld.

[0047] See also Figure 5The second embodiment of the present application provides another battery cell, which has a substantially similar structure to the battery cell 100 provided in the first embodiment, except that the weak areas 130 of the multiple pressure relief devices 13 provided on the cover plate 12 provided in the second embodiment of the present application have different areas. Since the two weak areas 130 have different areas, the calibers of the pressure relief ports after the explosion of each weak area 130 are different. In this way, different explosion pressures can be designed for the two weak areas 130 of different areas. In the process of gradually increasing the internal pressure of the battery cell 100, the weak area 130 with a smaller explosion pressure will first explode to release the pressure. When the internal pressure of the battery cell 100 cannot be effectively released and continues to increase, the weak area 130 with a larger explosion pressure will then explode to increase the pressure relief capacity, thereby achieving the explosion of one or two pressure relief devices at different pressure thresholds to achieve a gradient explosion effect. Specifically, in a specific implementation of the present embodiment, the lower limit ratio of the explosion pressure of the weak areas 130 of the two pressure relief devices 13 is between 1.2 and 1.5.

[0048] It is understandable that when the number of weak areas 130 is three or more, at least two different weak areas 130 can be set to have different areas, so that the diameters of the pressure relief ports of each weak area 130 after explosion are different. In this way, different explosion pressures can be designed for weak areas 130 of different areas. In the process of gradual increase in the internal pressure of the battery cell 100, one or part of the weak areas 130 with smaller explosion pressure will explode first to release the pressure. When the internal pressure of the battery cannot be effectively released and continues to increase, one or part of the weak areas 130 with larger explosion pressure will explode again to increase the pressure relief capacity, thereby realizing the explosion of different numbers of pressure relief devices at different pressure thresholds to achieve a gradient explosion effect.

[0049] It should be pointed out that when there are multiple pressure relief devices 13, the minimum distance between the edge of the weak zone 130 of each pressure relief device 13 and the weld can be designed to be the same. It is found through experiments that the (minimum) distance between the edge of the weak zone 130 and the weld determines the pressure change amplitude of the bursting pressure of the weak zone before and after the welding of the cover plate 12. The minimum distance between the edge of the weak zone of each pressure relief device and the weld is the same. Under the premise of minimizing the influence of the weld on the bursting pressure, it can be ensured that the pressure change amplitude of the weak zone 130 of each pressure relief device 13 also tends to be the same, so as to achieve an explosion-proof effect closer to the design parameters.

[0050] In another practicable solution of the present application, when there are multiple pressure relief devices 13, the minimum distance between the weak areas 130 of any two adjacent pressure relief devices 13 is greater than or equal to 3 mm. Keeping the minimum distance between the weak areas 130 of adjacent pressure relief devices 13 above 3 mm can minimize the deviation between the actual bursting pressure and the design threshold value caused by the weak areas 130 being too close to each other.

[0051] When there are multiple pressure relief devices 13, the multiple pressure relief devices 13 can be located between the positive terminal 14 and the negative terminal 15. It can be understood that in other embodiments, at least part of the pressure relief devices 13 can also be arranged on the other side opposite to the positive terminal 14, and the negative terminal 15 can be arranged between the positive terminal 14 and at least part of the pressure relief devices 13. In other words, from one side to the other side of the cover plate 12, the positive terminal 14, at least one pressure relief device 13, the negative terminal 15 and at least one pressure relief device 13 are respectively arranged. In this way, at least one pressure relief device 13 is arranged on both sides of the negative terminal 15. Furthermore, the areas of the weak areas 130 of the pressure relief devices 13 located on both sides of the negative terminal 15 may also be different. For example, when there are two pressure relief devices 13, the weak area 130 of a pressure relief device 13 closer to the positive terminal 14 (that is, the pressure relief device 13 located between the positive terminal 14 and the negative terminal 15) is larger, while the weak area 130 of a pressure relief device 13 farther from the positive terminal 14 is smaller. Of course, it can be understood that in another modified embodiment, the weak area 130 of a pressure relief device 13 closer to the positive terminal 14 (that is, the pressure relief device 13 located between the positive terminal 14 and the negative terminal 15) may be smaller, while the weak area 130 of a pressure relief device 13 farther from the positive terminal 14 may be larger. The significance of this multi-style setting method is that it can be flexibly adjusted and selected according to the actual design structure of the battery cell, and the arrangement is more flexible to avoid interference problems at the top of the battery cell.

[0052] In addition, it is understandable that Figure 5 The pressure relief devices 13 shown are all located on the same side of the liquid injection port 16, but in other modified implementations, multiple pressure relief devices 13 can be respectively arranged on both sides of the liquid injection port 16, such as Figure 6 The pressure relief devices 13 are arranged on both sides of the liquid injection port 16 to disperse the positions of the pressure relief devices 13 as much as possible, ensure that the pressure relief devices 13 are as far away from other surrounding components as possible, and avoid deviation between the actual bursting pressure and the design threshold as much as possible.

[0053] It should be noted that, during the production process of the battery cell 100, the area size of the weak area 130 of each pressure relief device 13 may have a predetermined value, wherein the area size of the weak area 130 of at least some of the pressure relief devices 13 has a first predetermined value, and the area size of the weak area 130 of at least some of the pressure relief devices 13 has a second predetermined value. The area size of the weak area 130 of each pressure relief device 13 is designed to be a predetermined value, and according to the actual pressure relief requirements of different battery products, pressure relief devices 13 of various sizes can be selected and combined, and then arranged on the cover plate 12 so that the battery cell 100 has the desired pressure relief capacity. In this way, by combining pressure relief devices of different specifications to meet the pressure relief requirements of different battery products, the development cost can be effectively reduced.

[0054] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A battery cell, characterized in that: include: a housing having an opening; A cover plate, covering the opening, wherein the cover plate and the shell are welded to form a weld; A pressure relief device is provided on the cover plate, the pressure relief device is configured as an explosion-proof valve, the pressure relief device is provided with a weak area, and the weak area is configured to be destroyed to release the internal pressure when the internal pressure or temperature of the battery cell reaches a threshold value; There are multiple pressure relief devices, the weak areas of at least two of the pressure relief devices are different in area, and the ratio of the lower limit of bursting pressure of the weak areas of the two pressure relief devices is between 1.2 and 1.5; Wherein, the minimum distance between the edge of the weak zone and the weld is greater than or equal to 3 mm.

2. The battery cell according to claim 1, characterized in that: The minimum distance between the edge of the weak zone of each of the pressure relief devices and the weld is the same.

3. The battery cell according to claim 1, characterized in that: The minimum distance between the weak areas of any two adjacent pressure relief devices is greater than or equal to 3 mm.

4. The battery cell according to claim 1, characterized in that: It also includes a positive terminal and a negative terminal arranged on the cover plate, and the plurality of pressure relief devices are all located between the positive terminal and the negative terminal.

5. The battery cell according to claim 4, characterized in that: It also includes a liquid injection port disposed on the cover plate and located between the positive terminal and the negative terminal, and a plurality of pressure relief devices are respectively disposed on both sides of the liquid injection port.

6. The battery cell according to claim 4, characterized in that: It also includes a liquid injection port disposed on the cover plate and located between the positive terminal and the negative terminal, and a plurality of pressure relief devices are disposed on the same side of the liquid injection port.

7. The battery cell according to claim 1, characterized in that: The weak area size of each of the pressure relief devices has a predetermined value, the weak area size of at least some of the pressure relief devices has a first predetermined value, and the weak area size of at least some of the pressure relief devices has a second predetermined value.

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