Battery monomer, pressure relief mechanism, battery and electric equipment

Abstract

The invention provides a battery monomer, a pressure relief mechanism, a battery and electric equipment. The battery monomer comprises a shell, an electrode assembly and a pressure relief mechanism, the shell is provided with a wall part, and the wall part is provided with a pressure relief hole. The electrode assembly is housed within the housing. The pressure relief mechanism covers the pressure relief hole, and the base material of the pressure relief mechanism is iron. The pressure relief mechanism comprises a weak part, a protruding part and a connecting part, and the weak part is configured to be at least partially damaged to release pressure when the pressure in the shell reaches a threshold value. The weak part is annular, the protruding part is located in an area defined by the weak part, and the connecting part is located on the outer side of the weak part and connected with the wall part. The protruding part is of a protruding structure protruding in the direction away from the electrode assembly. The minimum thickness H1 of the weak portion satisfies 0.01 mm < = H1 < = 0.2 mm. The protruding part forms pre-deformation on the inner side of the weak part, so that the weak part is convenient to crack and release pressure. Under the same bursting pressure, the thickness of the weak part can be larger, and the weak part is not easy to crack in advance due to stress, so that the service life of the single battery is prolonged.

Description

Battery cell, pressure relief mechanism, battery and electric device TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a battery cell, a pressure relief mechanism, a battery and an electric device. BACKGROUND

[0002] Batteries are widely used in the field of new energy, for example, electric vehicles, new energy vehicles, etc. New energy vehicles and electric vehicles have become a new trend in the development of the automobile industry. The development of battery technology needs to consider various design factors, such as energy density, discharge capacity, charge-discharge rate, and other performance parameters. In addition, the service life of the battery also needs to be considered. However, the service life of the current battery is relatively short.

[0003] SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a battery cell, a pressure relief mechanism, a battery and an electric device, which aims to improve the problem of short service life of the battery in the related art.

[0005] In a first aspect, the embodiments of the present application provide a battery cell, which comprises a shell, an electrode assembly and a pressure relief mechanism, the shell has a wall portion, the wall portion is provided with a pressure relief hole; the electrode assembly is contained in the shell; the pressure relief mechanism covers the pressure relief hole, the base material of the pressure relief mechanism is iron, the pressure relief mechanism comprises a weak portion, a raised portion and a connecting portion, the weak portion is configured to be at least partially destroyed to release the pressure when the pressure inside the shell reaches a threshold value, the weak portion is annular, the raised portion is located in the area surrounded by the weak portion, the connecting portion is located outside the weak portion and connects the wall portion, the raised portion is a raised structure raised in a direction away from the electrode assembly, the minimum thickness of the weak portion is H1, which satisfies 0.01mm≤H1≤0.2mm.

[0006] In the technical solution, the existing pressure relief mechanism is gradually arched away from the electrode assembly under the action of the internal pressure of the battery monomer when the pressure relief mechanism is in pressure relief. After arching, the pressure relief mechanism is opened under the action of the internal pressure of the battery monomer. In the embodiment of the application, the raised portion of the pressure relief mechanism is raised away from the electrode assembly. The raised portion forms a pre-deformation on the inner side of the weak portion, thereby facilitating the cracking of the weak portion for pressure relief. In this way, under the same burst pressure, the thickness of the weak portion can be larger, and the weak portion is not easily cracked in advance due to changes in the internal pressure of the battery monomer or external impact, which is beneficial to reduce the risk of the weak portion being damaged in advance and improve the service life of the battery monomer. When H1 is greater than or equal to 0.01 mm, the thickness of the weak portion is larger, and the weak portion is not easily cracked in advance due to changes in the internal pressure of the battery monomer or external impact, which is beneficial to reduce the risk of the weak portion being damaged in advance and improve the service life of the battery monomer. When H1 is less than or equal to 0.2 mm, the thickness of the weak portion is not too large, so that the pressure relief mechanism can be opened in time for pressure relief when the battery monomer is in thermal runaway, which is beneficial to improve the timeliness of the pressure relief mechanism. Therefore, when 0.01 mm≤H1≤0.2 mm, the service life of the battery monomer and the timeliness of pressure relief can be considered. In addition, the base material of the pressure relief mechanism is iron, which can effectively improve the structural strength of the pressure relief mechanism, reduce the risk of deformation of the pressure relief mechanism under stress, reduce the risk of the pressure relief mechanism opening the valve for pressure relief in advance, and improve the service life and reliability of the battery monomer. Compared with the aluminum material explosion-proof valve in the prior art, the thickness of the weak portion of the pressure relief mechanism provided in the embodiment of the application is smaller, and the thickness of the weak portion changes a little during manufacturing, and the burst pressure of the battery monomer will change greatly. By providing the raised portion, the thickness of the weak portion can be increased under the same burst pressure, and the larger the thickness of the weak portion, the easier it is to manufacture, thereby improving the consistency of the burst pressure of the plurality of battery monomers. Furthermore, when the battery monomer expands, the wall portion is deformed under stress, and the raised portion can be stretched under the action of external force, thereby reducing the pulling of the external force on the weak portion, reducing the risk of the weak portion being damaged in advance, and improving the service life of the battery monomer.

[0007] As an optional technical solution of the embodiment of the application, the boundary of the raised portion is at least partially adjacent to the boundary of the weak portion.

[0008] In the technical solution, the boundary of the raised portion is at least partially adjacent to the boundary of the weak portion. When the battery cell is depressurized, the raised portion can directly pull the weak portion through the adjacent portion, so that the portion of the weak portion adjacent to the boundary of the raised portion is subjected to greater shear force, thereby facilitating the opening of the weak portion for pressure relief. Under the same burst pressure, the thickness of the weak portion can be greater. During normal use of the battery cell, the weak portion is less likely to be prematurely cracked due to changes in internal pressure of the battery cell or external impact, thereby reducing the risk of premature damage to the weak portion and improving the service life of the battery cell. In addition, the greater the thickness of the weak portion, the easier it is to manufacture, thereby improving the consistency of the burst pressure of multiple battery cells.

[0009] As an optional technical solution of the embodiment, the boundary of the raised portion is completely adjacent to the boundary of the weak portion.

[0010] In the technical solution, the boundary of the raised portion is completely adjacent to the boundary of the weak portion. When the battery cell is depressurized, the raised portion can directly pull the weak portion, so that the weak portion is subjected to greater shear force, thereby facilitating the opening of the weak portion for pressure relief. Under the same burst pressure, the thickness of the weak portion can be greater. During normal use of the battery cell, the weak portion is less likely to be prematurely cracked due to changes in internal pressure of the battery cell or external impact, thereby reducing the risk of premature damage to the weak portion and improving the service life of the battery cell. In addition, the greater the thickness of the weak portion, the easier it is to manufacture, thereby improving the consistency of the burst pressure of multiple battery cells.

[0011] As an optional technical solution of the embodiment, the area enclosed by the weak portion is a pressure relief area, and the projection area of the pressure relief area along the thickness direction of the wall portion is S;

[0012] wherein, 100mm 2 ≤S≤450mm 2 , and 0.010mm≤H1≤0.160mm; or,

[0013] 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm; or,

[0014] 750mm 2 ≤S≤1250mm 2 , and 0.020mm≤H1≤0.180mm; or,

[0015] 1150mm 2 ≤S≤1650mm 2 , and 0.025mm≤H1≤0.190mm; or,

[0016] 1550mm 2 ≤S≤2100mm 2 , and 0.030mm≤H1≤0.200mm.

[0017] In the above technical solution, when the projection area of the pressure relief area is large, the pressure relief area is more easily affected by the internal pressure to cause the weak part to crack, therefore, when the projection area of the pressure relief area is increased, in order to ensure the same blasting pressure, the thickness of the weak part can be increased. When 100mm 2 ≤S≤450mm 2 , and H1≥0.010mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the internal pressure of the battery monomer or external impact, which is conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 100mm 2 ≤S≤450mm 2 , and H1≤0.160mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is conducive to improving the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 100mm 2 ≤S≤450mm 2 , and 0.010mm≤H1≤0.160mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0018] When 350mm 2 ≤S≤850mm 2 , and H1≥0.015mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the internal pressure of the battery monomer or external impact, which is conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 350mm 2 ≤S≤850mm 2 , and H1≤0.170mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is conducive to improving the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0019] When 750mm 2 ≤S≤1250mm 2 , and H1≥0.020mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the internal pressure of the battery monomer or external impact, which is conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 750mm 2≤ S ≤ 1250 mm 2 When 750 mm 2 ≤ S ≤ 1250 mm 2 , and 0.020 mm ≤ H1≤ 0.180 mm, the service life of the battery monomer and the timeliness of pressure relief can be taken into account.

[0020] When 1150 mm 2 ≤ S ≤ 1650 mm 2 , and H1≥ 0.025 mm, the thickness of the weak part is large, and the weak part is not easy to be broken in advance due to the change of the pressure inside the battery monomer or the impact from the outside, which is conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 1150 mm 2 ≤ S ≤ 1650 mm 2 , and H1≤ 0.190 mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is conducive to improving the timeliness of the pressure relief mechanism. Therefore, when 1550 mm 2 ≤ S ≤ 2100 mm 2 , and 0.025 mm ≤ H1≤ 0.190 mm, the service life of the battery monomer and the timeliness of pressure relief can be taken into account.

[0021] When 1550 mm 2 ≤ S ≤ 2100 mm 2 , and H1≥ 0.030 mm, the thickness of the weak part is large, and the weak part is not easy to be broken in advance due to the change of the pressure inside the battery monomer or the impact from the outside, which is conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 1550 mm 2 ≤ S ≤ 2100 mm 2 , and H1≤ 0.200 mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is conducive to improving the timeliness of the pressure relief mechanism. Therefore, when 1550 mm 2 ≤ S ≤ 2100 mm 2 , and 0.030 mm ≤ H1≤ 0.200 mm, the service life of the battery monomer and the timeliness of pressure relief can be taken into account.

[0022] As an optional technical solution of the embodiment of the application, 100 mm 2 ≤ S ≤ 450 mm 2 , and 0.020 mm ≤ H1≤ 0.160 mm; or,

[0023] 350 mm2 ≤S≤850mm 2 And 0.025mm≤H1≤0.170mm; or,

[0024] 750mm 2 ≤S≤1250mm 2 And 0.030mm≤H1≤0.180mm; or,

[0025] 1150mm 2 ≤S≤1650mm 2 And 0.035mm≤H1≤0.190mm; or,

[0026] 1550mm 2 ≤S≤2100mm 2 And 0.040mm≤H1≤0.200mm.

[0027] In the above technical solution, when 100mm 2 ≤S≤450mm 2 When H1 ≥ 0.020 mm, the thickness of the weak part is greater, making it less prone to premature cracking due to internal pressure changes or external impacts within the battery cell. This reduces the risk of premature damage to the weak part and improves the lifespan of the battery cell. When 100 mm... 2 ≤S≤450mm 2 When H1 ≤ 0.160 mm, the thickness of the weak part will not be too large, allowing the pressure relief mechanism to open more promptly in the event of thermal runaway of a single battery cell, thus improving the timeliness of pressure relief. Therefore, when 100 mm 2 ≤S≤450mm 2 Furthermore, when 0.020mm≤H1≤0.160mm, it is better able to balance the lifespan of individual battery cells and the timeliness of pressure relief.

[0028] When 350mm 2 ≤S≤850mm 2 When H1 ≥ 0.025 mm, the thickness of the weak part is greater, making it less prone to premature cracking due to internal pressure changes or external impacts within the battery cell. This reduces the risk of premature damage to the weak part and improves the lifespan of the battery cell. When 350 mm... 2 ≤S≤850mm 2 When H1 ≤ 0.170 mm, the thickness of the weak part will not be too large, allowing the pressure relief mechanism to open more promptly in the event of thermal runaway of a single battery cell, thus improving the timeliness of pressure relief. Therefore, when 350 mm 2 ≤S≤850mm 2, and 0.025mm≤H1≤0.170mm, the service life of the battery monomer and the timeliness of pressure relief can be considered.

[0029] When 750mm 2 ≤S≤1250mm 2 , and H1≥0.030mm, the thickness of the weak part is larger, the weak part is less likely to crack in advance due to changes in the internal pressure of the battery monomer or external impact, and it is more beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When 750mm 2 ≤S≤1250mm 2 , and H1≤0.180mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened more timely when the battery monomer is out of control, and it is more beneficial to improve the timeliness of the pressure relief mechanism. Therefore, when 750mm 2 ≤S≤1250mm 2 , and 0.030mm≤H1≤0.180mm, the service life of the battery monomer and the timeliness of pressure relief can be considered.

[0030] When 1150mm 2 ≤S≤1650mm 2 , and H1≥0.035mm, the thickness of the weak part is larger, the weak part is less likely to crack in advance due to changes in the internal pressure of the battery monomer or external impact, and it is more beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When 1150mm 2 ≤S≤1650mm 2 , and H1≤0.190mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened more timely when the battery monomer is out of control, and it is more beneficial to improve the timeliness of the pressure relief mechanism. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.035mm≤H1≤0.190mm, the service life of the battery monomer and the timeliness of pressure relief can be considered.

[0031] When 1550mm 2 ≤S≤2100mm 2 , and H1≥0.040mm, the thickness of the weak part is larger, the weak part is less likely to crack in advance due to changes in the internal pressure of the battery monomer or external impact, and it is more beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When 1550mm 2 ≤S≤2100mm 2, and H1≤0.200mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened more timely when the battery cell is in thermal runaway, and the timeliness of pressure relief of the pressure relief mechanism is improved. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.040mm≤H1≤0.200mm, the service life of the battery cell and the timeliness of pressure relief can be considered.

[0032] As an optional technical solution of the embodiment of the application, the protruding height of the protruding part is H2, and 0.2mm≤H2≤4.9mm is met.

[0033] In the above technical solution, when H2≥0.2mm, the protruding height of the protruding part is high, so that the deformation of the protruding part is more obvious, and under the same burst pressure, the thickness of the weak part is larger, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery cell. When H2≤4.9mm, the protruding height of the protruding part is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery or the battery cell and improve the energy density of the battery or the battery cell, and on the other hand, it is beneficial to reduce the risk of interference between the protruding part and other components. Therefore, when 0.2mm≤H2≤4.9mm, the service life and energy density of the battery cell can be considered, and the risk of interference between the protruding part and other components is reduced.

[0034] As an optional technical solution of the embodiment of the application, 0.3mm≤H2≤3mm.

[0035] In the above technical solution, when H2≥0.3mm, the protruding height of the protruding part is high, so that the deformation of the protruding part is more obvious, and under the same burst pressure, the thickness of the weak part can be larger, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery cell. When H2≤3mm, the protruding height of the protruding part is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery or the battery cell and improve the energy density of the battery or the battery cell, and on the other hand, it is beneficial to reduce the risk of interference between the protruding part and other components. Therefore, when 0.3mm≤H2≤3mm, the service life and energy density of the battery cell can be considered, and the risk of interference between the protruding part and other components is reduced.

[0036] As an optional technical solution of the embodiment of the application, the protruding part includes an arc-shaped part extending along an arc-shaped track, and the arc-shaped part includes a first end and a second end along the extension direction of the arc-shaped track, the first end and the second end are arranged along a first direction, and the first direction is parallel to the thickness direction of the wall with the largest surface area of the outer shell.

[0037] In the technical scheme, when the battery monomer expands, the wall with the largest outer surface area of the shell has the largest deformation degree. By arranging the protruding portion to include an arc-shaped portion extending along an arc-shaped track and arranging the first direction to be parallel to the thickness direction of the wall with the largest outer surface area of the shell, when the battery monomer expands, the protruding portion is more easily stretched under the external force, thereby further reducing the pulling of the weak portion by the external force, reducing the risk of the weak portion being damaged in advance, and facilitating improvement of the service life of the battery monomer.

[0038] As an optional technical scheme of the embodiment, the connecting portion is in a flat plate structure, and the weak portion is directly connected to the connecting portion and the protruding portion.

[0039] In the technical scheme, the connecting portion is in a flat plate structure, which facilitates connection of the connecting portion and the wall portion. The weak portion is directly connected to the connecting portion and the protruding portion. When the battery monomer is depressurized, the protruding portion can directly pull the weak portion, so that the weak portion is subjected to greater shearing force, thereby facilitating opening of the weak portion for pressure relief. In the case of the same burst pressure, the thickness of the weak portion can be greater, so that the weak portion is less likely to be cracked in advance due to changes in the pressure inside the battery monomer or external impact, thereby reducing the risk of the weak portion being damaged in advance and improving the service life of the battery monomer. In addition, the greater the thickness of the weak portion, the easier it is to manufacture, thereby facilitating improvement of the consistency of the burst pressure of the plurality of battery monomers.

[0040] As an optional technical scheme of the embodiment, the connecting portion is at least partially protruded in a direction away from the electrode assembly, and the weak portion is connected to a portion of the connecting portion farthest away from the electrode assembly.

[0041] In the technical scheme, by arranging the connecting portion to be at least partially protruded in a direction away from the electrode assembly and arranging the weak portion to be connected to a portion of the connecting portion farthest away from the electrode assembly, the connecting portion is less likely to affect the weak portion when the connecting portion is connected to the wall portion, thereby facilitating maintenance of the performance of the weak portion and improvement of the service life of the battery monomer.

[0042] As an optional technical scheme of the embodiment, the connecting portion is at least partially protruded in a direction facing the electrode assembly, and the weak portion is connected to a portion of the connecting portion closest to the electrode assembly.

[0043] In the technical solution, the connecting portion is at least partially raised in a direction facing the electrode assembly, the raised portion is raised in a direction away from the electrode assembly, the raising direction of the connecting portion and the raising direction of the raised portion are opposite, so that the raised portion can be raised by the raising height of the connecting portion, thereby facilitating reduction of the height of the raised portion beyond the surface of the connecting portion farthest from the electrode assembly, reduction of the occupation of the battery monomer or the internal space of the battery, and improvement of the energy density of the battery monomer or the battery. In addition, since the weak portion is connected to the part of the connecting portion closest to the electrode assembly, that is, the position of the weak portion is closer to the electrode assembly than the position of the fixed point of the connecting portion and the wall portion, and since one end of the connecting portion is constrained by the wall portion, under the action of air pressure, the part of the connecting portion raised in the direction facing the electrode assembly extrudes the weak portion, thereby inhibiting cracking of the weak portion and preventing creep failure of the weak portion during normal operation of the battery monomer, effectively prolonging the service life of the battery monomer.

[0044] As an optional technical solution of the embodiment, part of the connecting portion is inclined toward the inside of the shell; in the cross section of the connecting portion, the included angle between the inclined part of the connecting portion and the thickness direction of the wall portion is a, and the following condition is met: 30°≤a≤70°.

[0045] In the technical solution, when a≥30°, the inclination of the connecting portion is relatively large, and the constraint effect on the weak portion is good, thereby facilitating reduction of the risk of creep failure of the weak portion. When a≤70°, the inclination of the connecting portion is not too large, thereby facilitating reduction of stress concentration and reduction of the risk of brittle fracture.

[0046] As an optional technical solution of the embodiment, the raising height of the connecting portion is H3, and the following condition is met: 0.2mm≤H3≤7mm, and optionally, 0.2mm≤H3≤5mm.

[0047] In the technical solution, when H3≥0.2mm, the raising height of the connecting portion is relatively large, thereby facilitating reduction of the height of the raised portion beyond the surface of the connecting portion farthest from the electrode assembly, reduction of the occupation of the battery monomer or the internal space of the battery, and improvement of the energy density of the battery monomer or the battery. When H3≤7mm, the raising height of the connecting portion is not too large, thereby facilitating reduction of manufacturing difficulty and saving manufacturing cost. Therefore, when 0.2mm≤H3≤7mm, the occupation of the raised portion to the battery monomer or the internal space of the battery can be effectively reduced, and the manufacturing cost of the battery monomer can be reduced.

[0048] When H3 is greater than or equal to 0.2 mm, the height of the protrusion of the connecting portion is relatively large, thereby facilitating reduction of the height of the protrusion portion beyond the surface of the connecting portion farthest from the electrode assembly, reduction of the occupation of the battery monomer or the internal space of the battery, and improvement of the energy density of the battery monomer or the battery. When H3 is less than or equal to 5 mm, the height of the protrusion of the connecting portion is not excessively large, thereby facilitating reduction of the manufacturing difficulty and saving of the manufacturing cost. Therefore, when 0.2 mm≤H3≤5 mm, the occupation of the protrusion portion to the battery monomer or the internal space of the battery can be effectively reduced, and the manufacturing cost of the battery monomer can be reduced.

[0049] As an optional technical solution of the embodiment of the application, along the thickness direction of the wall portion, the connecting portion has a first surface farthest from the electrode assembly, and the protrusion portion does not exceed the first surface in the direction away from the electrode assembly.

[0050] In the above technical solution, by making the protrusion portion not exceed the first surface in the direction away from the electrode assembly, on the one hand, the occupation of the battery monomer or the internal space of the battery can be reduced, and the energy density of the battery monomer or the battery can be improved. On the other hand, the protrusion portion is not easily affected by external force, the risk of the weak portion being damaged in advance can be reduced, and the service life of the battery monomer can be improved.

[0051] As an optional technical solution of the embodiment of the application, along the thickness direction of the wall portion, the protrusion portion does not exceed the outer surface of the wall portion in the direction away from the electrode assembly.

[0052] In the above technical solution, by making the protrusion portion not exceed the outer surface of the wall portion in the direction away from the electrode assembly, on the one hand, the occupation of the internal space of the battery can be reduced, and the energy density of the battery can be improved. On the other hand, the protrusion portion is not easily interfered with other components, and is not easily affected by external force, the risk of the weak portion being damaged in advance can be reduced, and the service life of the battery monomer can be improved.

[0053] As an optional technical solution of the embodiment of the application, along the thickness direction of the wall portion, the connecting portion has a first surface farthest from the electrode assembly, the battery monomer includes an electrode terminal, the electrode terminal is arranged on the wall portion and at least partially protrudes from the outer surface of the wall portion, the electrode terminal has a second surface away from the electrode assembly; along the thickness direction of the wall portion, the protrusion portion exceeds the first surface in the direction in which the second surface points to the first surface, and does not exceed the second surface.

[0054] In the above technical solution, by making the raised portion extend beyond the first surface in the direction away from the electrode assembly, the deformation of the raised portion is more obvious. Under the same burst pressure, the thickness of the weak portion can be greater, which helps to reduce the risk of premature damage to the weak portion and improves the life of the battery cell. By making the raised portion not extend beyond the second surface in the direction away from the electrode assembly, the risk of interference between the raised portion and other electrical connection components is reduced.

[0055] As an optional technical solution in this application embodiment, the battery cell includes an electrode terminal, the electrode terminal is disposed on the wall portion and at least partially protrudes from the outer surface of the wall portion, the electrode terminal has a second surface facing away from the electrode assembly; along the thickness direction of the wall portion, the protrusion does not extend beyond the second surface in the direction facing away from the electrode assembly.

[0056] In the above technical solution, by ensuring that the raised portion does not extend beyond the second surface in the direction away from the electrode assembly, it is beneficial to reduce the risk of interference between the raised portion and other electrical connection components.

[0057] As an optional technical solution in this application embodiment, the battery cell includes an insulating member, which is disposed between the wall and the electrode assembly along the thickness direction of the wall; along the thickness direction of the wall, the insulating member is closer to the electrode assembly than the pressure relief mechanism.

[0058] In the above technical solution, by providing an insulating component between the wall and the electrode assembly, the wall and the electrode assembly can be insulated and isolated, reducing the risk of short circuit due to contact between the wall and the electrode assembly. By placing the insulating component closer to the electrode assembly than the pressure relief mechanism, the risk of contact between the electrode assembly and the pressure relief mechanism can be reduced, and a fluid channel can be left between the electrode assembly and the pressure relief mechanism, thereby facilitating pressure relief.

[0059] As an optional technical solution in this application embodiment, the pressure relief mechanism is made of 304 stainless steel, 305 stainless steel or 316 stainless steel.

[0060] In the above technical solutions, 304 stainless steel, 305 stainless steel and 316 stainless steel have advantages such as corrosion resistance, high temperature resistance and good processing performance. The pressure relief mechanism made of 304 stainless steel, 305 stainless steel or 316 stainless steel has high strength, which can reduce the risk of deformation of the pressure relief mechanism under stress, which is conducive to reducing the risk of premature valve opening and pressure relief of the pressure relief mechanism, which is conducive to improving the service life and reliability of battery cells, and conducive to improving the consistency of the explosion pressure of multiple battery cells.

[0061] As an optional technical solution of the embodiment of the present application, the pressure relief mechanism is provided with a pressure relief groove, and the pressure relief mechanism and the pressure relief groove correspondingly form the weak part.

[0062] In the above technical solution, the weak part is formed on the pressure relief mechanism by opening the pressure relief groove on the pressure relief mechanism. When the battery cell is relieved, the pressure relief mechanism is broken along at least part of the weak part, which is simple, convenient and low in cost.

[0063] As an optional technical solution of the embodiment of the present application, the cross section of the pressure relief groove is trapezoidal or conical.

[0064] In the above technical solution, when the cross section of the pressure relief groove is trapezoidal or conical, it is beneficial to the rapid opening of the pressure relief area when the battery cell is in thermal runaway.

[0065] As an optional technical solution of the embodiment of the present application, along the width direction of the pressure relief groove, the pressure relief groove comprises two groove side surfaces oppositely arranged, and the angle of the two groove side surfaces is b, which satisfies 30°≤b≤90°, and optionally 40°≤b≤80°.

[0066] In the above technical solution, when b≥30°, the pressure relief groove can be punched out more conveniently, reducing the processing difficulty of the pressure relief groove, thereby reducing the manufacturing cost of the battery cell. When b≤90°, the extrusion can be reduced. Therefore, when 30°≤b≤90°, both the manufacturing cost of the battery cell and the extrusion can be reduced.

[0067] When b≥40°, the pressure relief groove can be punched out more conveniently, reducing the processing difficulty of the pressure relief groove, thereby further reducing the manufacturing cost of the battery cell. When b≤80°, the extrusion can be further reduced. Therefore, when 40°≤b≤80°, both the manufacturing cost of the battery cell and the extrusion can be reduced.

[0068] As an optional technical solution of the embodiment of the present application, the weak part comprises a first weak section and a second weak section, the first weak section and the second weak section are connected end to end, and the thickness of the first weak section is less than the thickness of the second weak section.

[0069] In the above technical solution, by providing the second weak section, the strength of the pressure relief mechanism at the position of the second weak section is weakened, so that the pressure relief area is more easily turned open under the action of the internal gas pressure of the battery cell. Not only can the opening probability of the pressure relief area be improved, but also the opening speed of the pressure relief area can be improved, realizing rapid pressure relief, reducing the risk of explosion and fire of the battery cell, and being beneficial to improving the reliability of the battery cell.

[0070] As an optional technical solution of the embodiment of the application, the second weak section includes a third end and a fourth end along the extension direction of the second weak section, a line connecting the third end and the fourth end is a first line, and an included angle between the first line and the thickness direction of the wall with the largest outer surface area of the shell is C, which satisfies 0<=C<=45 degrees.

[0071] In the above technical solution, when 0<=C<=45 degrees, the included angle between the first line and the thickness direction of the wall with the largest outer surface area of the shell is small, and even if the pressure relief area is not completely opened, the high-temperature gas and / or flame sprayed out is not easy to direct to another battery monomer adjacent thereto, and it is not easy to cause thermal runaway of another battery monomer, which is beneficial to improve the reliability of the battery.

[0072] As an optional technical solution of the embodiment of the application, the first line is parallel to the thickness direction of the wall with the largest outer surface area of the shell.

[0073] In the above technical solution, the first line is parallel to the thickness direction of the wall with the largest outer surface area of the shell, and even if the pressure relief area is not completely opened, the high-temperature gas and / or flame sprayed out is not easy to direct to another battery monomer adjacent thereto, and it is not easy to cause thermal runaway of another battery monomer, which is beneficial to improve the reliability of the battery.

[0074] As an optional technical solution of the embodiment of the application, the second weak section extends along an arc trajectory.

[0075] In the above technical solution, when the second weak section extends along the arc trajectory, the area of the pressure relief area is larger, and it is convenient to open a larger opening for pressure relief.

[0076] As an optional technical solution of the embodiment of the application, the second weak section extends along a straight line trajectory.

[0077] In the above technical solution, when the second weak section extends along the straight line trajectory, it is convenient to process, and it has a good guiding effect on turning over of the pressure relief area.

[0078] As an optional technical solution of the embodiment of the application, the minimum thickness of the second weak section is H4, which satisfies 0.05mm<=H4<=0.2mm, and optionally, 0.05mm<=H4<=0.15mm.

[0079] In the technical solution, when H4 is greater than or equal to 0.05 mm, the thickness of the second weak section is relatively large, which can reduce the risk of the second weak section being cracked due to the change of the internal gas pressure of the battery monomer or external impact, and is conducive to improving the reliability of the battery monomer. When H4 is less than or equal to 0.2 mm, the thickness of the second weak section is not too large, which is conducive to reducing the resistance of the pressure relief area to turn over, facilitating the rapid turning over of the pressure relief area, and is conducive to improving the timeliness of the pressure relief of the battery monomer. Therefore, when 0.05 mm≤H4≤0.2 mm, the thickness of the second weak section is moderate, the second weak section is neither easy to be cracked due to the change of the internal gas pressure of the battery monomer or external impact, nor is it difficult for the pressure relief area to turn over, which is conducive to improving the timeliness of the pressure relief of the battery monomer.

[0080] When H4 is greater than or equal to 0.05 mm, the thickness of the second weak section is relatively large, which can reduce the risk of the second weak section being cracked due to the change of the internal gas pressure of the battery monomer or external impact, and is conducive to improving the reliability of the battery monomer. When H4 is less than or equal to 0.15 mm, the thickness of the second weak section is not too large, which is more conducive to reducing the resistance of the pressure relief area to turn over, facilitating the rapid turning over of the pressure relief area, and is more conducive to improving the timeliness of the pressure relief of the battery monomer. Therefore, when 0.05 mm≤H4≤0.2 mm, the thickness of the second weak section is moderate, the second weak section is neither easy to be cracked due to the change of the internal gas pressure of the battery monomer or external impact, nor is it difficult for the pressure relief area to turn over, which is conducive to improving the timeliness of the pressure relief of the battery monomer.

[0081] As an optional technical solution of the embodiment of the application, the thickness of the pressure relief mechanism is H5, and 0.05 mm≤H5≤0.5 mm, and optionally, 0.05 mm≤H5≤0.3 mm.

[0082] In the technical solution, when H5 is greater than or equal to 0.05 mm, the thickness of the pressure relief mechanism is relatively large, the pressure relief mechanism has high structural strength, which can reduce the risk of the pressure relief mechanism being deformed under stress, and is conducive to improving the service life and reliability of the battery monomer. When H5 is less than or equal to 0.5 mm, the thickness of the pressure relief mechanism is not too large, which is conducive to controlling the manufacturing cost of the battery monomer. Therefore, when 0.05 mm≤H5≤0.5 mm, the service life, reliability and manufacturing cost of the battery monomer can be considered.

[0083] When H5 is greater than or equal to 0.05 mm, the thickness of the pressure relief mechanism is relatively large, the pressure relief mechanism has high structural strength, which can reduce the risk of the pressure relief mechanism being deformed under stress, and is conducive to improving the service life and reliability of the battery monomer. When H5 is less than or equal to 0.3 mm, the thickness of the pressure relief mechanism is not too large, which is more conducive to controlling the manufacturing cost of the battery monomer. Therefore, when 0.05 mm≤H5≤0.3 mm, the service life, reliability and manufacturing cost of the battery monomer can be considered.

[0084] As an optional technical solution of the embodiment of the application, the base material of the wall portion is iron, and the pressure relief mechanism is welded to the wall portion.

[0085] In the above technical solution, the base material of the pressure relief mechanism and the wall portion is iron. On the one hand, the structural strength of the wall portion and the pressure relief mechanism can be effectively improved, the risk of deformation of the wall portion and the pressure relief mechanism under stress can be reduced, the risk of the pressure relief mechanism opening the valve to relieve pressure in advance can be reduced, and the service life and reliability of the battery monomer can be improved. On the other hand, the pressure relief mechanism and the wall portion are easier to weld, the phenomenon of welding cracks between the pressure relief mechanism and the end cover can be reduced, the risk of liquid leakage of the battery monomer can be reduced, and the reliability of the battery monomer can be improved.

[0086] In a second aspect, the embodiment of the application also provides a pressure relief mechanism, the base material of the pressure relief mechanism is iron, the pressure relief mechanism comprises a weak portion, a raised portion and a connecting portion, the weak portion is configured to be at least partially destroyed when the battery monomer relieves pressure, the weak portion is annular, the raised portion is located in the area surrounded by the weak portion, and the connecting portion is located on the outside of the weak portion. The raised portion is a raised structure raised along the thickness direction of the pressure relief mechanism, and the minimum thickness of the weak portion is H1, which satisfies 0.01mm≤H1≤0.2mm.

[0087] As an optional technical solution of the embodiment of the application, the area enclosed by the weak portion is a pressure relief area, and the projection area of the pressure relief area along the thickness direction of the pressure relief mechanism is S.

[0088] Wherein, 100mm 2 ≤S≤450mm 2 , and 0.010mm≤H1≤0.160mm; or,

[0089] 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm; or,

[0090] 750mm 2 ≤S≤1250mm 2 , and 0.020mm≤H1≤0.180mm; or,

[0091] 1150mm 2 ≤S≤1650mm 2 , and 0.025mm≤H1≤0.190mm; or,

[0092] 1550mm 2 ≤S≤2100mm 2 , and 0.030mm≤H1≤0.200mm.

[0093] In the above technical solution, when the projection area of the pressure relief area is large, the pressure relief area is more easily affected by the internal pressure to cause the weak part to crack, therefore, when the projection area of the pressure relief area is increased, in order to ensure the same blasting pressure, the thickness of the weak part can be increased. When 100mm 2 ≤S≤450mm 2 , and H1≥0.010mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the internal pressure of the battery monomer or external impact, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When 100mm 2 ≤S≤450mm 2 , and H1≤0.160mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is beneficial to improve the timeliness of the pressure relief mechanism. Therefore, when 100mm 2 ≤S≤450mm 2 , and 0.010mm≤H1≤0.160mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0094] When 350mm 2 ≤S≤850mm 2 , and H1≥0.015mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the internal pressure of the battery monomer or external impact, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When 350mm 2 ≤S≤850mm 2 , and H1≤0.170mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is beneficial to improve the timeliness of the pressure relief mechanism. Therefore, when 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0095] When 750mm 2 ≤S≤1250mm 2 , and H1≥0.020mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the internal pressure of the battery monomer or external impact, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When 750mm 2 ≤S≤1250mm 2, and H1≤0.180mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery cell is out of control, which is conducive to improving the timeliness of the pressure relief mechanism. Therefore, when 750mm 2 ≤S≤1250mm 2 , and 0.020mm≤H1≤0.180mm, the service life of the battery cell and the timeliness of pressure relief can be considered.

[0096] When 1150mm 2 ≤S≤1650mm 2 , and H1≥0.025mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the pressure inside the battery cell or the impact of the outside world, which is conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery cell. When 1150mm 2 ≤S≤1650mm 2 , and H1≤0.190mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery cell is out of control, which is conducive to improving the timeliness of the pressure relief mechanism. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.025mm≤H1≤0.190mm, the service life of the battery cell and the timeliness of pressure relief can be considered.

[0097] When 1550mm 2 ≤S≤2100mm 2 , and H1≥0.030mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the pressure inside the battery cell or the impact of the outside world, which is conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery cell. When 1550mm 2 ≤S≤2100mm 2 , and H1≤0.200mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery cell is out of control, which is conducive to improving the timeliness of the pressure relief mechanism. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.030mm≤H1≤0.200mm, the service life of the battery cell and the timeliness of pressure relief can be considered.

[0098] As an optional technical solution of the present application, 100mm 2 ≤S≤450mm 2 , and 0.020mm≤H1≤0.160mm; or,

[0099] 350mm 2 ≤S≤850mm2 , and 0.025mm≤H1≤0.170mm; or,

[0100] 750mm 2 ≤S≤1250mm 2 , and 0.030mm≤H1≤0.180mm; or,

[0101] 1150mm 2 ≤S≤1650mm 2 , and 0.035mm≤H1≤0.190mm; or,

[0102] 1550mm 2 ≤S≤2100mm 2 , and 0.040mm≤H1≤0.200mm.

[0103] In the above technical solutions, when 100mm 2 ≤S≤450mm 2 , and H1≥0.020mm, the thickness of the weak part is larger, the weak part is less likely to be cracked in advance due to the change of the pressure inside the battery monomer or external impact, and it is more conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 100mm 2 ≤S≤450mm 2 , and H1≤0.160mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can open the pressure relief more timely when the battery monomer is out of control, and it is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 100mm 2 ≤S≤450mm 2 , and 0.02mm≤H1≤0.160mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0104] When 350mm 2 ≤S≤850mm 2 , and H1≥0.025mm, the thickness of the weak part is larger, the weak part is less likely to be cracked in advance due to the change of the pressure inside the battery monomer or external impact, and it is more conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 350mm 2 ≤S≤850mm 2 , and H1≤0.170mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can open the pressure relief more timely when the battery monomer is out of control, and it is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 350mm 2 ≤S≤850mm 2 , and 0.025mm≤H1≤0.170mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0105] when 750mm 2 ≤S≤1250mm 2 , and H1≥0.030mm, the thickness of the weak part is larger, the weak part is less likely to be cracked in advance due to the change of the pressure inside the battery monomer or the external impact, and it is more conducive to reducing the risk of the weak part being damaged in advance, and it is more conducive to improving the service life of the battery monomer. When 750mm 2 ≤S≤1250mm 2 , and H1≤0.180mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can open the pressure relief more timely when the battery monomer is out of control, and it is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 750mm 2 ≤S≤1250mm 2 , and 0.030mm≤H1≤0.180mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0106] when 1150mm 2 ≤S≤1650mm 2 , and H1≥0.035mm, the thickness of the weak part is larger, the weak part is less likely to be cracked in advance due to the change of the pressure inside the battery monomer or the external impact, and it is more conducive to reducing the risk of the weak part being damaged in advance, and it is more conducive to improving the service life of the battery monomer. When 1150mm 2 ≤S≤1650mm 2 , and H1≤0.190mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can open the pressure relief more timely when the battery monomer is out of control, and it is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.035mm≤H1≤0.190mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0107] when 1550mm 2 ≤S≤2100mm 2 , and H1≥0.040mm, the thickness of the weak part is larger, the weak part is less likely to be cracked in advance due to the change of the pressure inside the battery monomer or the external impact, and it is more conducive to reducing the risk of the weak part being damaged in advance, and it is more conducive to improving the service life of the battery monomer. When 1550mm 2 ≤S≤2100mm 2 , and H1≤0.200mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can open the pressure relief more timely when the battery monomer is out of control, and it is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 1550mm 2 ≤S≤2100mm 2, and 0.040mm≤H1≤0.200mm, the service life of the battery monomer and the pressure relief timeliness can be considered.

[0108] As an optional technical solution of the embodiment of the application, the protruding height of the protruding part is H2, and 0.2mm≤H2≤4.9mm is met.

[0109] In the above technical solution, when H2≥0.2mm, the protruding height of the protruding part is high, so the deformation of the protruding part is more obvious, and under the same burst pressure, the thickness of the weak part is larger, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When H2≤4.9mm, the protruding height of the protruding part is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery or the battery monomer and improve the energy density of the battery or the battery monomer, and on the other hand, it is beneficial to reduce the risk of interference between the protruding part and other components. Therefore, when 0.2mm≤H2≤4.9mm, the service life and the energy density of the battery monomer can be considered, and the risk of interference between the protruding part and other components can be reduced.

[0110] As an optional technical solution of the embodiment of the application, 0.3mm≤H2≤3mm is met.

[0111] In the above technical solution, when H2≥0.3mm, the protruding height of the protruding part is high, so the deformation of the protruding part is more obvious, and under the same burst pressure, the thickness of the weak part can be larger, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When H2≤3mm, the protruding height of the protruding part is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery or the battery monomer and improve the energy density of the battery or the battery monomer, and on the other hand, it is beneficial to reduce the risk of interference between the protruding part and other components. Therefore, when 0.3mm≤H2≤3mm, the service life and the energy density of the battery monomer can be considered, and the risk of interference between the protruding part and other components can be reduced.

[0112] In a third aspect, the embodiment of the application also provides a battery, which comprises the battery monomer.

[0113] As an optional technical solution of the embodiment of the application, the battery comprises a plurality of battery monomers, and the plurality of battery monomers are arranged along a second direction; the weak part comprises a first weak section and a second weak section, the first weak section and the second weak section are connected end to end, the thickness of the first weak section is smaller than the thickness of the second weak section; along the extension direction of the second weak section, the second weak section comprises a third end and a fourth end, the line connecting the third end and the fourth end is a first line, and the included angle between the first line and the second direction is D, which satisfies 0≤D≤45°.

[0114] In the technical solution, when 0≤D≤45°, the included angle between the first line and the second direction is small, and when the battery cell is depressurized, the high-temperature gas and / or flame sprayed out is not easy to direct to another battery cell adjacent to it, and it is not easy to cause thermal runaway of another battery cell, which is beneficial to improve the reliability of the battery.

[0115] As an optional technical solution of the embodiment of the present application, the first line is parallel to the second direction.

[0116] In the technical solution, the first line is parallel to the second direction, and when the battery cell is depressurized, the high-temperature gas and / or flame sprayed out is not easy to direct to another battery cell adjacent to it, and it is not easy to cause thermal runaway of another battery cell, which is beneficial to improve the reliability of the battery.

[0117] As an optional technical solution of the embodiment of the present application, the second direction is the thickness direction of the wall with the largest outer surface area of the shell.

[0118] In the technical solution, by arranging the plurality of battery cells along the thickness direction of the wall with the largest outer surface area of the shell, it is beneficial to fully utilize the space and improve the energy density of the battery.

[0119] In a fourth aspect, the embodiment of the present application also provides a power utilization device, which comprises the battery cell described above, and the battery cell is used to provide electric energy for the power utilization device. BRIEF DESCRIPTION OF DRAWINGS

[0120] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0121] FIG. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application;

[0122] FIG. 2 is an exploded view of a battery provided by some embodiments of the present application;

[0123] FIG. 3 is a structural schematic diagram of a battery cell provided by some embodiments of the present application;

[0124] FIG. 4 is an exploded view of a battery cell provided by some embodiments of the present application;

[0125] FIG. 5 is a top view of a wall provided by some embodiments of the present application;

[0126] Fig. 6 is a sectional view of the position A-A in Fig. 5;

[0127] Fig. 7 is a sectional view of a wall portion according to some embodiments of the application;

[0128] Fig. 8 is a schematic view of a pressure relief mechanism according to some embodiments of the application;

[0129] Fig. 9 is a top view of a pressure relief mechanism according to some embodiments of the application;

[0130] Fig. 10 is a sectional view of the position B-B in Fig. 9;

[0131] Fig. 11 is a sectional view of a pressure relief mechanism according to some embodiments of the application;

[0132] Fig. 12 is a sectional view of a pressure relief mechanism according to some embodiments of the application;

[0133] Fig. 13 is an enlarged view of the position C in Fig. 10;

[0134] Fig. 14 is a schematic view of a pressure relief mechanism according to some embodiments of the application.

[0135] Fig. 14 is a schematic view of a pressure relief mechanism according to some embodiments of the application. DETAILED DESCRIPTION

[0136] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0137] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the specification herein is for describing particular embodiments only and is not intended to be limiting of the application; the use herein of terms such as "comprise", "comprising", "comprises", "including", "includes" or "contain" or "containing" or "have" or "has" or "having" or "include" or "includes" or "comprise" or "comprising" is to be construed as specifying the presence of stated features or steps but does not preclude the presence or addition of one or more other features or steps. The use herein of terms such as "first", "second" and "third" and / or the use of terms such as "the" or "said", does not limit the scope of the application, but are simply used for ease of reference.

[0138] Reference throughout this application to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another.

[0139] In the description of the application, it is necessary to explain that, unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium; can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0140] The term "and / or" in the application is only a description of the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the existence of A alone, the existence of A and B together, and the existence of B alone. In addition, the character " / " in the application generally represents an "or" relationship between the front and rear associated objects.

[0141] In the embodiments of the application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length and width of various components in the embodiments of the application shown in the drawings, and the overall thickness, length and width of the integrated device are only exemplary and should not constitute any limitation on the application.

[0142] "Multiple" appearing in the application means more than two (including two).

[0143] In the embodiments of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to use.

[0144] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead-acid battery, etc. The embodiments of the present application are not limited thereto.

[0145] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging of the battery cell, active ions (e.g., lithium ions) are inserted and extracted between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, and can prevent the positive and negative electrodes from shorting to some extent, while allowing the active ions to pass through.

[0146] In some embodiments, the positive electrode can be a positive electrode tab, which can include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0147] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode active material is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0148] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, aluminum with silver plating on the surface, stainless steel with silver plating on the surface, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, or titanium, etc. can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0149] As an example, the positive electrode active material can include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination with two or more. Among them, examples of lithium-containing phosphates can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP for short)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Examples of lithium transition metal oxides can include, but are not limited to, at least one of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn1 / 3 O2(also can be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also can be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also can be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also can be referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof.

[0150] In some embodiments, the positive electrode can employ a foam metal. The foam metal can be a foam nickel, a foam copper, a foam aluminum, a foam alloy, etc. When the foam metal is used as the positive electrode, the surface of the foam metal can not be provided with a positive electrode active material, or of course can be provided with a positive electrode active material. As an example, the foam metal can also be filled or / and deposited with a lithium source material, a potassium metal or a sodium metal, the lithium source material being a lithium metal and / or a lithium-rich material.

[0151] In some embodiments, the negative electrode can be a negative electrode tab, which can include a negative electrode current collector.

[0152] As an example, the negative electrode current collector can employ a metal foil, a foam metal or a composite current collector. For example, as the metal foil, silver surface treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, nickel or titanium, etc. can be employed. The foam metal can be a foam nickel, a foam copper, a foam aluminum, a foam alloy, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0153] As an example, the negative electrode tab can include a negative electrode current collector and a negative electrode active material provided on at least one surface of the negative electrode current collector.

[0154] As an example, the negative current collector has two surfaces opposite in the thickness direction thereof, and the negative active material is disposed on either one or both of the two surfaces of the negative current collector.

[0155] As an example, the negative active material can employ a negative active material for a battery cell known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative active material can also be used. These negative active materials can be used alone or in combination of two or more.

[0156] In some embodiments, the material of the positive current collector can be aluminum, and the material of the negative current collector can be copper.

[0157] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0158] In some embodiments, the separator is a separator film. The separator film can be of various types, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0159] As an example, the material of the separator film can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film. When the separator film is a multi-layer composite film, the materials of the respective layers can be the same or different. The separator can be a separate component located between the positive and negative electrodes, or can be attached to the surface of the positive and negative electrodes.

[0160] In some embodiments, the separator is a solid-state electrolyte. The solid-state electrolyte is disposed between the positive electrode and the negative electrode, and functions to transport ions and separate the positive and negative electrodes.

[0161] In some embodiments, the battery cell further includes an electrolyte that functions to conduct ions between the positive and negative electrodes. The electrolyte can be in a liquid state, a gel state, or a solid state. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[0162] In some embodiments, the electrolyte salt can include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoroboric oxalate, lithium boric oxalate, lithium difluorophosphoric oxalate, and lithium tetrafluorophosphoric oxalate.

[0163] In some embodiments, the solvent can include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butyl sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be selected from ether solvents. The ether solvents can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0164] In some embodiments, the gel-state electrolyte includes a polymer as a skeleton network of the electrolyte, in combination with an ionic liquid-lithium salt.

[0165] In some embodiments, the solid-state electrolyte includes a polymer solid-state electrolyte, an inorganic solid-state electrolyte, a composite solid-state electrolyte.

[0166] As an example, the polymer solid-state electrolyte can be a polyether (polyethylene oxide), a polysiloxane, a polycarbonate, a polyacrylonitrile, a polyvinylidene fluoride, a polymethyl methacrylate, a single-ion polymer, a polyionic liquid-lithium salt, a cellulose, or the like.

[0167] As an example, the inorganic solid-state electrolyte can include one or more of an oxide solid-state electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON thin film), a sulfide solid-state electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorous sulfide, argyrodite), amorphous sulfide), and a halide solid-state electrolyte, a nitride solid-state electrolyte, and a hydride solid-state electrolyte.

[0168] As an example, the composite solid-state electrolyte is formed by adding an inorganic solid-state electrolyte filler to a polymer solid-state electrolyte.

[0169] In some embodiments, the electrode assembly is in a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound into the jelly-roll structure.

[0170] In some embodiments, the electrode assembly is in a stack structure.

[0171] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be alternately stacked.

[0172] As an example, a plurality of positive electrode sheets can be provided, and the negative electrode sheet is folded to form a plurality of folded segments that are stacked, with one positive electrode sheet being sandwiched between adjacent folded segments.

[0173] As an example, the positive electrode tab and the negative electrode tab are each folded to form a plurality of folded segments that are stacked.

[0174] As an example, the separator can be provided in plurality, and each of the plurality of separators is provided between any adjacent positive electrode tab or negative electrode tab.

[0175] As an example, the separator can be provided in plurality, and each of the plurality of separators is provided between any adjacent positive electrode tab or negative electrode tab.

[0176] In some embodiments, the electrode assembly can have a cylindrical shape, a flat shape, or a polygonal shape.

[0177] In some embodiments, the electrode assembly can be provided with a tab, which can lead current out of the electrode assembly. The tab can include a positive tab and a negative tab.

[0178] In some embodiments, the battery cell can include a case. The case can be used to encapsulate the electrode assembly and other components such as electrolyte. The case can be a steel case, an aluminum case, a plastic case (e.g., polypropylene), a composite metal case (e.g., a copper-aluminum composite case), or an aluminum-plastic film.

[0179] In some embodiments, the case can be a sealed structure or a non-sealed structure. As an example, when the case is a sealed structure, the case can protect the electrode assembly and prevent, to some extent, leakage of electrolyte and the like. When the case is a non-sealed structure, the case can protect the electrode assembly, and a sealing bag can be further included between the case and the electrode assembly. The sealing bag can be used to encapsulate the electrode assembly and electrolyte and the like. Specifically, the sealing bag can be a bag-shaped insulating member or an aluminum-plastic film.

[0180] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell having another shape. The prismatic battery cell can include, but is not limited to, a square battery cell, a blade battery cell, and a polygonal battery cell such as a hexagonal battery cell.

[0181] The battery referred to in the embodiments of the present application means a single physical module including one or more battery cells to provide a higher voltage and capacity.

[0182] In some embodiments, the battery can be a battery module. When a plurality of battery cells are included, the plurality of battery cells can be arranged and fixed to form a battery module.

[0183] In some embodiments, the battery can be a battery pack. The battery pack can include a case and a battery cell or a battery module, which can be accommodated in the case.

[0184] In some embodiments, the box can be part of a chassis structure of a vehicle. For example, portions of the box can become at least part of a floor of the vehicle, or portions of the box can become at least part of cross members and longitudinal members of the vehicle.

[0185] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, and the like.

[0186] At present, from the development of market situation, the application of battery is more and more widely. The battery is not only applied to the energy storage power supply system of hydropower, thermal power, wind power and solar power station, but also widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, military equipment, aerospace and other fields. With the continuous expansion of the application field of battery, the demand of its market is also increasing.

[0187] The development of battery technology needs to consider many design factors, such as energy density, discharge capacity, charge-discharge rate and other performance parameters. In addition, the life of the battery also needs to be considered. However, the current battery has a short life.

[0188] In order to improve the reliability of the battery monomer, the prior art sets a pressure relief mechanism on the battery monomer, and a weak part is arranged on the pressure relief mechanism. When the internal pressure of the battery monomer reaches the burst pressure, the weak part is cracked to release the internal pressure of the battery monomer, so as to reduce the risk of explosion and fire of the battery monomer.

[0189] However, in the prior art, the thickness of the weak part is small, and the weak part is easy to crack under the action of the change of the internal pressure of the battery monomer or the external impact, that is, the weak part has been cracked before the internal pressure of the battery monomer reaches the expected burst pressure, resulting in the battery monomer being scrapped in advance and the short life of the battery monomer. If the thickness of the weak part is directly increased, the burst pressure will be increased, and the risk of thermal runaway of the battery monomer will be increased.

[0190] Therefore, the embodiments of the present application provide a battery monomer. The battery monomer includes a shell, an electrode assembly and a pressure relief mechanism. The shell has a wall part, and the wall part is provided with a pressure relief hole. The electrode assembly is contained in the shell, and the pressure relief mechanism covers the pressure relief hole. The base material of the pressure relief mechanism is iron. The pressure relief mechanism includes a weak part, a raised part and a connecting part. The weak part is configured to be at least partially destroyed to release pressure when the internal pressure of the shell reaches a threshold value. The weak part is annular. The raised part is located in the area surrounded by the weak part. The connecting part is located on the outside of the weak part and connects the wall part. The raised part is a raised structure raised in the direction away from the electrode assembly. The minimum thickness of the weak part is H1, and 0.01mm≤H1≤0.2mm is satisfied.

[0191] The existing pressure relief mechanism is gradually arched away from the electrode assembly under the action of the internal pressure of the battery monomer when the pressure relief mechanism is relieved, and then opens the pressure relief under the action of the internal pressure of the battery monomer. In the embodiments of the present application, the raised portion of the pressure relief mechanism is raised away from the electrode assembly, and the raised portion forms a pre-deformation on the inner side of the weak portion, thereby facilitating the cracking of the weak portion to relieve pressure. In this way, under the same burst pressure, the thickness of the weak portion can be larger, and the weak portion is not easy to crack in advance due to changes in the internal pressure of the battery monomer or external impact when the battery monomer is in normal use, which is conducive to reducing the risk of the weak portion being damaged in advance and improving the service life of the battery monomer. When H1 is greater than or equal to 0.01 mm, the thickness of the weak portion is larger, and the weak portion is not easy to crack in advance due to changes in the internal pressure of the battery monomer or external impact, which is conducive to reducing the risk of the weak portion being damaged in advance and improving the service life of the battery monomer. When H1 is less than or equal to 0.2 mm, the thickness of the weak portion is not too large, so that the pressure relief mechanism can open in time to relieve pressure when the battery monomer is in thermal runaway, which is conducive to improving the timeliness of the pressure relief mechanism. Therefore, when 0.01 mm≤H1≤0.2 mm, the service life of the battery monomer and the timeliness of pressure relief can be considered. In addition, the base material of the pressure relief mechanism is iron, which can effectively improve the structural strength of the pressure relief mechanism, reduce the risk of deformation of the pressure relief mechanism under stress, reduce the risk of the pressure relief mechanism opening the valve to relieve pressure in advance, and improve the service life and reliability of the battery monomer. Compared with the aluminum material explosion-proof valve in the prior art, the thickness of the weak portion of the pressure relief mechanism provided in the embodiments of the present application is smaller, and the thickness of the weak portion changes a little during manufacturing, and the burst pressure of the battery monomer will change greatly. By providing the raised portion, the thickness of the weak portion can be increased under the same burst pressure, and the larger the thickness of the weak portion, the easier it is to manufacture, thereby improving the consistency of the burst pressure of multiple battery monomers. Furthermore, when the battery monomer expands, the wall portion is deformed under stress, and the raised portion can be stretched under external force, thereby reducing the pulling of the weak portion by external force, reducing the risk of the weak portion being damaged in advance, and improving the service life of the battery monomer.

[0192] The technical solutions described in the embodiments of the present application are suitable for batteries and electric devices using batteries.

[0193] The electric device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, and an electric tool, etc. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, etc.; the electric toy includes a fixed or mobile electric toy, for example, a game machine, an electric car toy, an electric ship toy, an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, which can include but is not limited to an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, and an electric planer, etc.

[0194] The following embodiments are described by taking the vehicle 1000 as an example for convenience of illustration.

[0195] Please refer to FIG. 1, which is a structural schematic diagram of a vehicle 1000 provided by some embodiments of the present application. The vehicle 1000 can be a fuel automobile, a gas automobile or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid automobile or a range extended automobile, etc. The vehicle 1000 is internally provided with a battery 100, which can be arranged at the bottom, the head or the tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000, for example, the battery 100 can be used as an operating power supply of the vehicle 1000. The vehicle 1000 can further include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to supply power to the motor 300, for example, to meet the working power demand of the vehicle 1000 during starting, navigation and driving.

[0196] In some embodiments of the present application, the battery 100 can not only be used as an operating power supply of the vehicle 1000, but also be used as a driving power supply of the vehicle 1000, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1000.

[0197] Please refer to FIG. 2, which is an exploded view of the battery 100 provided by some embodiments of the present application. The battery 100 includes a box body 10 and a battery monomer 20, and the battery monomer 20 is contained in the box body 10. Among them, the box body 10 is used to provide a containing space for the battery monomer 20, and the box body 10 can adopt various structures. In some embodiments, the box body 10 can include a first part 11 and a second part 12, and the first part 11 and the second part 12 are mutually covered. The first part 11 and the second part 12 jointly define a containing space for containing the battery monomer 20. The second part 12 can be a hollow structure with one end open, and the first part 11 can be a plate-shaped structure, which is covered on the open side of the second part 12 to jointly define the containing space with the second part 12. The first part 11 and the second part 12 can also be hollow structures with one side open, and the open side of the first part 11 is covered on the open side of the second part 12. Of course, the box body 10 formed by the first part 11 and the second part 12 can be various shapes, such as a cylinder, a cuboid, etc.

[0198] In the battery 100, the battery cells 20 can be multiple, and the multiple battery cells 20 can be connected in series, in parallel, or in a mixed manner. The mixed manner means that the multiple battery cells 20 are connected in series and in parallel. The multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed manner, and the whole of the multiple battery cells 20 is accommodated in the case 10. Of course, the battery 100 can also be in the form of a battery module in which the multiple battery cells 20 are connected in series, in parallel, or in a mixed manner, and the multiple battery modules are connected in series, in parallel, or in a mixed manner to form a whole and are accommodated in the case 10. The battery 100 can also include other structures. For example, the battery 100 can also include a current combiner for electrically connecting the multiple battery cells 20.

[0199] Each battery cell 20 can be a secondary battery cell or a primary battery cell. The battery cell 20 can also be a lithium-sulfur battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, but is not limited thereto. The battery cell 20 can be in the shape of a cylinder, a flat body, a cuboid, or other shapes.

[0200] Please refer to FIG. 3, FIG. 4, FIG. 5, and FIG. 6. FIG. 3 is a structural schematic diagram of a battery cell 20 according to some embodiments of the present application. FIG. 4 is an exploded view of the battery cell 20 according to some embodiments of the present application. FIG. 5 is a top view of a wall portion 213 according to some embodiments of the present application. FIG. 6 is a sectional view of the position A-A in FIG. 5. The battery cell 20 according to some embodiments of the present application includes an outer shell 21, an electrode assembly 23, and a pressure relief mechanism 24. The outer shell 21 has a wall portion 213 provided with a pressure relief hole 2131. The electrode assembly 23 is accommodated in the outer shell 21. The pressure relief mechanism 24 covers the pressure relief hole 2131. The base material of the pressure relief mechanism 24 is iron. The pressure relief mechanism 24 includes a weak portion 2421, a raised portion 24221, and a connecting portion 241. The weak portion 2421 is configured to be at least partially destroyed to release pressure when the pressure inside the outer shell 21 reaches a threshold value. The weak portion 2421 is annular. The raised portion 24221 is located in the area surrounded by the weak portion 2421. The connecting portion 241 is located outside the weak portion 2421 and connects the wall portion 213. The raised portion 24221 is a raised structure raised in a direction away from the electrode assembly 23. The minimum thickness H1 of the weak portion 2421 satisfies 0.01 mm ≤ H1 ≤ 0.2 mm.

[0201] The battery cell 20 refers to the smallest unit that constitutes the battery 100.

[0202] The outer shell 21 includes a shell 211 and an end cover 212. The shell 211 has an open-ended accommodation space for accommodating the electrode assembly 23. The end cover 212 is connected to the shell 211 and closes the opening.

[0203] The end cover 212 refers to a component that covers the opening of the case 211 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cover 212 can be adapted to the shape of the case 211 to fit the case 211. Optionally, the end cover 212 can be made of a material with certain hardness and strength, such as an aluminum alloy, so that the end cover 212 is less likely to deform when subjected to a pressing impact, allowing the battery cell 20 to have higher structural strength and improved reliability. The material of the end cover 212 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. The end cover 212 is also provided with an electrode terminal 25, which is used to electrically connect with the tab 232 of the electrode assembly 23 to input or output the electric energy of the battery cell 20. The electrode terminal 25 can be directly connected with the tab 232, for example, the electrode terminal 25 is directly welded with the tab 232. The electrode terminal 25 can also be indirectly connected with the tab 232, for example, the electrode terminal 25 is indirectly connected with the tab 232 through a current collecting member.

[0204] The case 211 is a component used to fit the end cover 212 to form the internal environment of the battery cell 20, which can be used to accommodate the electrode assembly 23, the electrolyte, and other components. The case 211 and the end cover 212 can be independent components, and an opening can be provided on the case 211, and the end cover 212 is used to cover the opening to form the internal environment of the battery cell 20. Without limitation, the end cover 212 and the case 211 can also be integrated, specifically, the end cover 212 and the case 211 can form a common joint surface before other components enter the case, and when it is necessary to seal the inside of the case 211, the end cover 212 is used to cover the case 211. The case 211 can have various shapes and sizes, such as a cuboid, a cylinder, a hexagonal prism, etc. Specifically, the shape of the case 211 can be determined according to the specific shape and size of the electrode assembly 23. The material of the case 211 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0205] The electrode assembly 23 is a component in which electrochemical reactions occur in the battery cell 20. One or more electrode assemblies 23 can be contained in the case 211. The electrode assembly 23 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and an isolation film is usually provided between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet have a portion with active material constituting a main body 231 of the electrode assembly 23, and a portion without active material constituting a tab 232 of the positive electrode sheet and the negative electrode sheet, respectively. The positive tab and the negative tab can be located together at one end of the main body 231 or at two ends of the main body 231, respectively. During the charging and discharging process of the battery 100, the positive active material and the negative active material react with the electrolyte.

[0206] The wall portion 213 can be an end cover 212 of the housing 21, or a wall of the casing 211 of the housing 21. Exemplarily, in FIGS. 3 and 4, the wall portion 213 is an end cover 212. In other embodiments, the wall portion 213 is a bottom wall of the casing 211 opposite to the end cover 212. In yet other embodiments, the wall portion 213 can also be a side wall of the casing 211 adjacent to the end cover 212 and connected to the end cover 212.

[0207] The pressure relief mechanism 24 is a component for opening when the internal pressure or temperature of the battery cell 20 reaches the burst pressure, to release the internal pressure of the battery cell 20. The pressure relief mechanism 24 is a component mounted on the wall portion 213, and the pressure relief mechanism 24 is provided separately from the wall portion 213 and connected to the wall portion 213. In manufacturing, a pressure relief hole 2131 is formed on the wall portion 213, and the pressure relief mechanism 24 and the wall portion 213 are provided separately and finally connected together, so that the pressure relief mechanism 24 covers the pressure relief hole 2131. For example, the pressure relief mechanism 24 can be welded to the wall portion 213. The pressure relief mechanism 24 can be a rupture disc mounted on the wall portion 213. The wall of the housing 21 which is the wall portion 213 can be determined by the position of the pressure relief mechanism 24. For example, when the pressure relief mechanism 24 is provided on the end cover 212, the end cover 212 is the wall portion 213. When the pressure relief mechanism 24 is provided on the bottom wall of the casing 211, the bottom wall is the wall portion 213. When the pressure relief mechanism 24 is provided on the side wall of the casing 211, the side wall is the wall portion 213.

[0208] The "base material of the pressure relief mechanism 24 is iron" means that the material with the largest mass percentage in the material of the pressure relief mechanism 24 is iron. For example, the material of the pressure relief mechanism 24 can be carbon steel or stainless steel.

[0209] The weakened portion 2421 functions to relieve pressure, for enabling the pressure relief mechanism 24 to break along at least a portion of the weakened portion 2421 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, to release the internal pressure of the battery cell 20. In some embodiments, the strength of the pressure relief mechanism 24 at the position of the weakened portion 2421 can be lower than the strength of the pressure relief mechanism 24 at other positions, so that the weakened portion 2421 can break under the internal pressure when the internal pressure or temperature of the battery cell 20 reaches the predetermined value, to release the internal pressure of the battery cell 20. In other embodiments, the melting point of the pressure relief mechanism 24 at the position of the weakened portion 2421 can be lower than the melting point of the pressure relief mechanism 24 at other positions. In this way, the weakened portion 2421 can break under high temperature when the internal pressure or temperature of the battery cell 20 reaches the predetermined value, to release the internal pressure of the battery cell 20.

[0210] The weak portion 2421 is annular, and can be circular or elliptical. The weak portion 2421 divides the pressure relief mechanism 24 into two parts, one part being on the inner side of the weak portion 2421 and the other part being on the outer side of the weak portion 2421.

[0211] The raised portion 24221 is on the inner side of the weak portion 2421, and is a raised structure raised in a direction away from the electrode assembly 23. The raised structure is a structure in which the inner surface and the outer surface are both arched in a direction away from the electrode assembly 23.

[0212] The connecting portion 241 is on the outer side of the weak portion 2421, and is a portion of the pressure relief mechanism 24 for connecting the wall portion 213. For example, the connecting portion 241 can be welded to the wall portion 213.

[0213] Referring to FIGS. 4 and 6, the thickness direction of the wall portion 213 is the X direction shown in the figures.

[0214] H1 represents the minimum thickness of the weak portion 2421 in the thickness direction of the wall portion 213. When measuring, the thickness at different positions can be measured multiple times and the average value is taken as H1.

[0215] The minimum thickness of the weak portion 2421 in the thickness direction of the wall portion 213 can be: H1 = 0.01 mm, 0.02 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, etc.

[0216] The existing pressure relief mechanism 24 is gradually arched away from the electrode assembly 23 under the action of the internal pressure of the battery monomer 20 when pressure relief, and then opens under the action of the internal pressure of the battery monomer 20. In the embodiments of the present application, the bulge part 24221 of the pressure relief mechanism 24 is arched away from the electrode assembly 23, and the bulge part 24221 forms a pre-deformation on the inner side of the weak part 2421, thereby facilitating the cracking of the weak part 2421 for pressure relief. In this way, under the same burst pressure, the thickness of the weak part 2421 can be larger, and the weak part 2421 is not easy to crack in advance due to changes in the internal pressure of the battery monomer 20 or external impact when the battery monomer 20 is normally used, which is beneficial to reduce the risk of the weak part 2421 being damaged in advance and improve the service life of the battery monomer 20. When H1≥0.01mm, the thickness of the weak part 2421 is larger, and the weak part 2421 is not easy to crack in advance due to changes in the internal pressure of the battery monomer 20 or external impact, which is beneficial to reduce the risk of the weak part 2421 being damaged in advance and improve the service life of the battery monomer 20. When H1≤0.2mm, the thickness of the weak part 2421 is not too large, so that the pressure relief mechanism 24 can open in time for pressure relief when the battery monomer 20 is out of control, which is beneficial to improve the timeliness of the pressure relief mechanism 24. Therefore, when 0.01mm≤H1≤0.2mm, the service life of the battery monomer 20 and the timeliness of pressure relief can be considered. In addition, the base material of the pressure relief mechanism 24 is iron, which can effectively improve the structural strength of the pressure relief mechanism 24, reduce the risk of deformation of the pressure relief mechanism 24 under stress, reduce the risk of the pressure relief mechanism 24 opening the valve for pressure relief in advance, and improve the service life and reliability of the battery monomer 20. Compared with the aluminum material explosion-proof valve in the prior art, the thickness of the weak part 2421 of the pressure relief mechanism 24 provided in the embodiments of the present application is smaller, and the thickness of the weak part 2421 changes a little during manufacturing, and the burst pressure of the battery monomer 20 will change a lot. By providing the bulge part 24221, the thickness of the weak part 2421 can be increased under the same burst pressure, and the larger the thickness of the weak part 2421, the easier it is to manufacture, thereby improving the consistency of the burst pressure of the plurality of battery monomers 20. Furthermore, when the battery monomer 20 expands, the wall part 213 is deformed under stress, and the bulge part 24221 can be stretched under external force, thereby reducing the pulling of the weak part 2421 by external force, reducing the risk of the weak part 2421 being damaged in advance, and improving the service life of the battery monomer 20.

[0217] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6 and FIG. 7, FIG. 7 is a cross-sectional view of the wall part 213 provided in some embodiments of the present application. In some embodiments, the boundary of the bulge part 24221 at least partially adjoins the boundary of the weak part 2421.

[0218] The "boundary of the protrusion 24221 at least partially abutting the boundary of the weakened portion 2421" can also be understood as the boundary of the protrusion 24221 at least partially overlapping the boundary of the weakened portion 2421. In other words, the weakened portion 2421 has at least a part directly connected to the protrusion 24221.

[0219] Please refer to FIG. 7, in which the boundary of the right end of the protrusion 24221 abuts the boundary of the weakened portion 2421, i.e., the right end of the protrusion 24221 is directly connected to the weakened portion 2421. The boundary of the left end of the protrusion 24221 is arranged with a gap from the boundary of the weakened portion 2421, i.e., the left end of the protrusion 24221 is arranged with a gap from the weakened portion 2421.

[0220] By making the boundary of the protrusion 24221 at least partially abut the boundary of the weakened portion 2421, when the battery cell 20 is depressurized, the protrusion 24221 can directly pull the weakened portion 2421 through the abutting part, so that the part of the weakened portion 2421 abutting the boundary of the protrusion 24221 is subjected to a greater shearing force, thereby facilitating the opening of the weakened portion 2421 to depressurize. Under the same burst pressure, the thickness of the weakened portion 2421 can be greater, and the weakened portion 2421 is less likely to be prematurely cracked due to changes in pressure inside the battery cell 20 or external impact during normal use of the battery cell 20, which is conducive to reducing the risk of premature damage to the weakened portion 2421 and improving the service life of the battery cell 20. In addition, the greater the thickness of the weakened portion 2421, the easier it is to manufacture, thereby facilitating the consistency of the burst pressure of multiple battery cells 20.

[0221] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6 and FIG. 7, the boundary of the protrusion 24221 completely abuts the boundary of the weakened portion 2421.

[0222] The "boundary of the protrusion 24221 at least partially abutting the boundary of the weakened portion 2421" can also be understood as the boundary of the protrusion 24221 completely overlapping the boundary of the weakened portion 2421. It should be noted that the weakened portion 2421 has an inner boundary close to the protrusion 24221 and an outer boundary arranged outside the inner boundary, and here it is only required that the boundary of the protrusion 24221 completely overlaps the inner boundary of the weakened portion 2421.

[0223] The "boundary of the protrusion 24221 at least partially abutting the boundary of the weakened portion 2421" can also be said that each part of the weakened portion 2421 is directly connected to the protrusion 24221.

[0224] Please refer to FIG. 6, in the embodiment shown in FIG. 6, both left and right ends of the protrusion 24221 are directly connected to the weakened portion 2421.

[0225] By making the boundary of the protrusion 24221 completely contiguous with the boundary of the weak portion 2421, when the battery cell 20 is depressurized, the protrusion 24221 can directly pull the weak portion 2421, so that the weak portion 2421 is subjected to greater shear force, thereby facilitating the opening of the weak portion 2421 to depressurize. In the case of the same burst pressure, the thickness of the weak portion 2421 can be greater, and the weak portion 2421 is not easy to be cracked in advance due to the pressure change inside the battery cell 20 or external impact when the battery cell 20 is normally used, which is conducive to reducing the risk of the weak portion 2421 being damaged in advance and improving the service life of the battery cell 20. In addition, the greater the thickness of the weak portion 2421, the easier it is to manufacture, thereby facilitating the consistency of the burst pressure of the plurality of battery cells 20.

[0226] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9, FIG. 8 is a structural schematic diagram of the pressure relief mechanism 24 provided by some embodiments of the application. FIG. 9 is a top view schematic diagram of the pressure relief mechanism 24 provided by some embodiments of the application. In some embodiments, the area enclosed by the weak portion 2421 is a pressure relief area 2422. The projection area of the pressure relief area 2422 along the thickness direction of the wall portion 213 is S. Wherein, 100mm 2 ≤S≤450mm 2 , and 0.010mm≤H1≤0.160mm; or,

[0227] 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm; or,

[0228] 750mm 2 ≤S≤1250mm 2 , and 0.020mm≤H1≤0.180mm; or,

[0229] 1150mm 2 ≤S≤1650mm 2 , and 0.025mm≤H1≤0.190mm; or,

[0230] 1550mm 2 ≤S≤2100mm 2 , and 0.030mm≤H1≤0.200mm.

[0231] The pressure relief area 2422 is the area of the pressure relief mechanism 24 enclosed by the weak portion 2421, that is, the area inside the weak portion 2421 of the pressure relief mechanism 24. When the battery cell 20 is depressurized, the weak portion 2421 cracks along the edge of the pressure relief area 2422, so that the pressure relief area 2422 can be opened to depressurize.

[0232] The pressure relief area 2422 includes the above-mentioned protrusion 24221. For example, the pressure relief area 2422 can be partially protruded in a direction away from the electrode assembly 23 to form the protrusion 24221, or the pressure relief area 2422 can be entirely protruded in a direction away from the electrode assembly 23 to form the protrusion 24221. Referring to FIG. 6, in the embodiment shown in FIG. 6, the pressure relief area 2422 is entirely protruded in a direction away from the electrode assembly 23 to form the protrusion 24221, and the pressure relief area 2422 is the protrusion 24221.

[0233] S represents the projected area of the pressure relief area 2422 in the thickness direction of the wall portion 213. Referring to FIG. 9, the S is indicated by the meshed line. It should be noted that the meshed line is only used to facilitate the display of S, and does not represent any physical meaning.

[0234] The projected area of the pressure relief area 2422 in the thickness direction of the wall portion 213 can be: S = 100 mm 2 , 150 mm 2 , 200 mm 2 , 250 mm 2 , 300 mm 2 , 350 mm 2 , 400 mm 2 , 450 mm 2 , 500 mm 2 , 550 mm 2 , 600 mm 2 , 650 mm 2 , 700 mm 2 , 750 mm 2 , 800 mm 2 , 850 mm 2 , 900 mm 2 , 950 mm 2 , 1000 mm 2 , 1050 mm 2 , 1100 mm 2 , 1150 mm 2 , 1200 mm 2 , 1250 mm 2 , 1300 mm 2 , 1350 mm 2 , 1400 mm 2 , 1450 mm 2 , 1500 mm 2 , 1550 mm 2 , 1600 mm 2 , 1650 mm 2 , 1700 mm 2 , 1750 mm 21800mm 2 1850mm 2 1900mm 2 1950mm 2 2000mm 2 2050mm 2 2100mm 2 etc.

[0235] When 100mm 2 ≤ S ≤ 450mm 2 , 0.010mm ≤ H1 ≤ 0.160mm. When 100mm 2 ≤ S ≤ 450mm 2 , the minimum thickness of the weak portion 2421 along the thickness direction of the wall portion 213 can be: 0.010mm, 0.020mm, 0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, etc.

[0236] When the projection area of the pressure relief area 2422 is large, the pressure relief area 2422 is more likely to be broken by the internal pressure of the weak portion 2421, so when the projection area of the pressure relief area 2422 is increased, in order to ensure the same burst pressure, the thickness of the weak portion 2421 can be increased. When 100mm 2 ≤ S ≤ 450mm 2 , and H1 ≥ 0.010mm, the thickness of the weak portion 2421 is large, and the weak portion 2421 is not easy to be broken in advance due to the change of the internal pressure of the battery monomer 20 or external impact, which is beneficial to reduce the risk of the weak portion 2421 being damaged in advance, and is beneficial to improve the service life of the battery monomer 20. When 100mm 2 ≤ S ≤ 450mm 2 , and H1 ≤ 0.160mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 100mm 2 ≤ S ≤ 450mm 2 , and 0.010mm ≤ H1 ≤ 0.160mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be considered.

[0237] When 350mm 2 ≤ S ≤ 850mm 2 , 0.015mm ≤ H1 ≤ 0.170mm. When 350mm 2≤S≤850mm 2 When the weak part 2421 has a minimum thickness along the thickness direction of the wall part 213, it can be: H1 = 0.015mm, 0.020mm, 0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, 0.170mm, etc.

[0238] When 350mm 2 ≤S≤850mm 2 When H1 ≥ 0.015 mm, the thickness of the weak part 2421 is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 2421 and improves the lifespan of the battery cell 20. When 350 mm... 2 ≤S≤850mm 2 When H1 ≤ 0.170 mm, the thickness of the weak part 2421 will not be too large, allowing the pressure relief mechanism 24 to open and relieve pressure in a timely manner when the battery cell 20 experiences thermal runaway, thus improving the timeliness of pressure relief. Therefore, when 350 mm 2 ≤S≤850mm 2 When 0.015mm≤H1≤0.170mm, the lifespan of the battery cell 20 and the timeliness of pressure relief can be taken into account.

[0239] When 750mm 2 ≤S≤1250mm 2 When 0.020mm ≤ H1 ≤ 0.180mm. When 750mm 2 ≤S≤1250mm 2 When the weak part 2421 has a minimum thickness along the thickness direction of the wall part 213, it can be: H1 = 0.020mm, 0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, 0.170mm, 0.180mm, etc.

[0240] When 750mm 2 ≤S≤1250mm 2, and H1 is greater than or equal to 0.020 mm, the thickness of the weak portion 2421 is relatively large, the weak portion 2421 is not prone to being cracked in advance due to changes in pressure inside the battery monomer 20 or external impact, which is conducive to reducing the risk of the weak portion 2421 being damaged in advance and is conducive to improving the service life of the battery monomer 20. When 750 mm 2 ≤ S ≤ 1250 mm 2 , and H1 is less than or equal to 0.180 mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is out of control, which is conducive to improving the timeliness of pressure relief of the pressure relief mechanism 24. Therefore, when 750 mm 2 ≤ S ≤ 1250 mm 2 , and 0.020 mm ≤ H1 ≤ 0.180 mm, the service life and timeliness of pressure relief of the battery monomer 20 can be considered.

[0241] When 1150 mm 2 ≤ S ≤ 1650 mm 2 , 0.025 mm ≤ H1 ≤ 0.190 mm. When 1150 mm 2 ≤ S ≤ 1650 mm 2 , the minimum thickness of the weak portion 2421 along the thickness direction of the wall portion 213 can be: H1 = 0.025 mm, 0.030 mm, 0.040 mm, 0.050 mm, 0.060 mm, 0.070 mm, 0.080 mm, 0.090 mm, 0.100 mm, 0.110 mm, 0.120 mm, 0.130 mm, 0.140 mm, 0.150 mm, 0.160 mm, 0.170 mm, 0.180 mm, 0.190 mm, etc.

[0242] When 1150 mm 2 ≤ S ≤ 1650 mm 2 , and H1 is greater than or equal to 0.025 mm, the thickness of the weak portion 2421 is relatively large, the weak portion 2421 is not prone to being cracked in advance due to changes in pressure inside the battery monomer 20 or external impact, which is conducive to reducing the risk of the weak portion 2421 being damaged in advance and is conducive to improving the service life of the battery monomer 20. When 1150 mm 2 ≤ S ≤ 1650 mm 2 , and H1 is less than or equal to 0.190 mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is out of control, which is conducive to improving the timeliness of pressure relief of the pressure relief mechanism 24. Therefore, when 1550 mm 2 ≤ S ≤ 2100 mm 2 , and 0.025 mm ≤ H1 ≤ 0.190 mm, the service life and timeliness of pressure relief of the battery monomer 20 can be considered.

[0243] When 1550mm 2 ≤S≤2100mm 2 When 0.030mm ≤ H1 ≤ 0.200mm. When 1550mm 2 ≤S≤2100mm 2 When the weak part 2421 has a minimum thickness along the thickness direction of the wall part 213, it can be: H1 = 0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, 0.170mm, 0.180mm, 0.190mm, 0.200mm, etc.

[0244] When 1550mm 2 ≤S≤2100mm 2 When H1 ≥ 0.030 mm, the thickness of the weak part 2421 is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 2421 and improves the lifespan of the battery cell 20. When 1550 mm... 2 ≤S≤2100mm 2 When H1 ≤ 0.200 mm, the thickness of the weak part 2421 will not be too large, allowing the pressure relief mechanism 24 to open and relieve pressure in a timely manner when the battery cell 20 experiences thermal runaway, thus improving the timeliness of pressure relief by the pressure relief mechanism 24. Therefore, when 1550 mm 2 ≤S≤2100mm 2 When 0.030mm≤H1≤0.200mm, the lifespan of the battery cell 20 and the timeliness of pressure relief can be taken into account.

[0245] In some embodiments, 100mm 2 ≤S≤450mm 2 And 0.020mm≤H1≤0.160mm; or,

[0246] 350mm 2 ≤S≤850mm 2 And 0.025mm≤H1≤0.170mm; or,

[0247] 750mm 2 ≤S≤1250mm 2 And 0.030mm≤H1≤0.180mm; or,

[0248] 1150mm 2 ≤S≤1650mm2 and 0.035 mm ≤ H1≤ 0.190 mm; or,

[0249] 1550 mm 2 ≤ S ≤ 2100 mm 2 and 0.040 mm ≤ H1≤ 0.200 mm.

[0250] When 100 mm 2 ≤ S ≤ 450 mm 2 , 0.020 mm ≤ H1≤ 0.160 mm. When 100 mm 2 ≤ S ≤ 450 mm 2 , the minimum thickness of the weak portion 2421 along the thickness direction of the wall portion 213 can be: H1= 0.020 mm, 0.025 mm, 0.030 mm, 0.035 mm, 0.040 mm, 0.045 mm, 0.050 mm, 0.055 mm, 0.060 mm, 0.065 mm, 0.070 mm, 0.075 mm, 0.080 mm, 0.085 mm, 0.090 mm, 0.095 mm, 0.100 mm, 0.105 mm, 0.110 mm, 0.115 mm, 0.120 mm, 0.125 mm, 0.130 mm, 0.135 mm, 0.140 mm, 0.145 mm, 0.150 mm, 0.155 mm, 0.160 mm, etc.

[0251] When 100 mm 2 ≤ S ≤ 450 mm 2 and H1≥ 0.020 mm, the thickness of the weak portion 2421 is greater, the weak portion 2421 is less likely to be broken in advance due to the pressure change inside the battery monomer 20 or external impact, and it is more conducive to reducing the risk of the weak portion 2421 being damaged in advance and improving the service life of the battery monomer 20. When 100 mm 2 ≤ S ≤ 450 mm 2 and H1≤ 0.160 mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can open the pressure relief more timely when the battery monomer 20 is out of control, and it is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 100 mm 2 ≤ S ≤ 450 mm 2 and 0.020 mm ≤ H1≤ 0.160 mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be considered.

[0252] When 350 mm 2 ≤ S ≤ 850 mm 2 , 0.025 mm ≤ H1≤ 0.170 mm. When 350 mm 2 ≤ S ≤ 850 mm2 When 350mm

[0253] When 350mm 2 ≤ S ≤ 850mm 2 , and H1≥ 0.025mm, the thickness of the weak portion 2421 is larger, the weak portion 2421 is less likely to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, and it is more conducive to reducing the risk of the weak portion 2421 being damaged in advance, and more conducive to improving the service life of the battery monomer 20. When 350mm 2 ≤ S ≤ 850mm 2 , and H1≤ 0.170mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can open the pressure relief more timely when the battery monomer 20 is out of control, and it is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 350mm 2 ≤ S ≤ 850mm 2 , and 0.025mm≤ H1≤ 0.170mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be considered.

[0254] When 750mm 2 ≤ S ≤ 1250mm 2 , 0.030mm≤ H1≤ 0.180mm. When 750mm 2 ≤ S ≤ 1250mm 2When the weak part 2421 has a minimum thickness along the thickness direction of the wall part 213, it can be: H1 = 0.030mm, 0.035mm, 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm, 0.080mm, 0.085mm, 0.090mm, 0.095mm, 0.100mm, 0.105mm, 0.110mm, 0.115mm, 0.120mm, 0.125mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.155mm, 0.160mm, 0.165mm, 0.170mm, 0.175mm, 0.180mm, etc.

[0255] When 750mm 2 ≤S≤1250mm 2 When H1 ≥ 0.030 mm, the thickness of the weak part 2421 is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 2421 and improves the lifespan of the battery cell 20. When 750 mm... 2 ≤S≤1250mm 2 When H1 ≤ 0.180 mm, the thickness of the weak part 2421 will not be too large, allowing the pressure relief mechanism 24 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 750 mm 2 ≤S≤1250mm 2 Furthermore, when H1 is 0.030mm≤H1≤0.180mm, it is better able to balance the service life of the battery cell 20 and the timeliness of pressure relief.

[0256] When 1150mm 2 ≤S≤1650mm 2 When 0.035mm ≤ H1 ≤ 0.190mm. When 1150mm 2 ≤S≤1650mm 2When the weak part 2421 has a minimum thickness along the thickness direction of the wall part 213, it can be: H1 = 0.035mm, 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm, 0.080mm, 0.085mm, 0.090mm, 0.095mm, 0.100mm, 0.105mm. 0.110mm, 0.115mm, 0.120mm, 0.125mm, 0.130mm, 0.125mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.155mm, 0.160mm, 0.165mm, 0.170mm, 0.175mm, 0.180mm, 0.185mm, 0.190mm, etc.

[0257] When 1150mm 2 ≤S≤1650mm 2 When H1 ≥ 0.035 mm, the thickness of the weak part 2421 is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 2421 and improves the lifespan of the battery cell 20. When 1150 mm... 2 ≤S≤1650mm 2 When H1 ≤ 0.190 mm, the thickness of the weak part 2421 will not be too large, allowing the pressure relief mechanism 24 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 1550 mm 2 ≤S≤2100mm 2 Furthermore, when H1 is 0.035mm≤H1≤0.190mm, it is better able to balance the service life of the battery cell 20 and the timeliness of pressure relief.

[0258] When 1550mm 2 ≤S≤2100mm 2 When 0.040mm ≤ H1 ≤ 0.200mm. When 1550mm 2 ≤S≤2100mm 2When the thin part 2421 has a minimum thickness along the thickness direction of the wall part 213, it can be: H1 = 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm, 0.080mm, 0.085mm, 0.090mm, 0.095mm, 0.100mm, 0.105mm, 0.110mm, 0.115mm, 0.120mm, 0.12 5mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.125mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.155mm, 0.160mm, 0.165mm, 0.170mm, 0.175mm, 0.180mm, 0.185mm, 0.190mm, 0.195mm, 0.200mm, etc.

[0259] When 1550mm 2 ≤S≤2100mm 2 When H1 ≥ 0.040 mm, the thickness of the weak part 2421 is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 2421 and improves the lifespan of the battery cell 20. When 1550 mm... 2 ≤S≤2100mm 2 When H1 ≤ 0.200 mm, the thickness of the weak part 2421 will not be too large, allowing the pressure relief mechanism 24 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 1550 mm 2 ≤S≤2100mm 2 Furthermore, when 0.040mm≤H1≤0.200mm, it is better able to balance the service life of the battery cell 20 and the timeliness of pressure relief.

[0260] Please refer to Figures 3, 4, 5, 6 and 7. The height of the raised part 24221 is H2, which satisfies: 0.2mm≤H2≤4.9mm.

[0261] H2 represents the height of the protrusion of the protrusion portion 24221. In some embodiments, the pressure relief mechanism 24 is provided with a pressure relief groove 245, and the position corresponding to the pressure relief groove 245 of the pressure relief mechanism 24 forms the weak portion 2421. Please refer to FIG. 6 and FIG. 7. When the pressure relief groove 245 is arranged on the side of the pressure relief mechanism 24 away from the electrode assembly 23, the weak portion 2421 has a first surface facing the electrode assembly 23, and the maximum distance from the first surface to the inner surface of the protrusion portion 24221 can be measured as H2. When the pressure relief groove 245 is arranged on the side of the pressure relief mechanism 24 facing the electrode assembly 23, the weak portion 2421 has a second surface away from the electrode assembly 23, and the maximum distance from the second surface to the outer surface of the protrusion portion 24221 can be measured as H2. When the pressure relief mechanism 24 is provided with pressure relief grooves 245 on both sides along the thickness direction of the wall portion 213, the maximum distance from the opening of the pressure relief groove 245 arranged on the side of the pressure relief mechanism 24 away from the electrode assembly 23 to the outer surface of the protrusion portion 24221 can be measured as H2.

[0262] The height of the protrusion of the protrusion portion 24221 can be: H2 = 0.2 mm, 0.25, 0.3, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 4.9 mm, etc.

[0263] When H2 ≥ 0.2 mm, the height of the protrusion of the protrusion portion 24221 is relatively high, so the deformation of the protrusion portion 24221 is more obvious. Under the same burst pressure, the thickness of the weak portion 2421 is larger, which is beneficial to reduce the risk of the weak portion 2421 being damaged in advance and improve the service life of the battery cell 20. When H2 ≤ 4.9 mm, the height of the protrusion of the protrusion portion 24221 is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery 100 or the battery cell 20, improve the energy density of the battery 100 or the battery cell 20, and on the other hand, it is beneficial to reduce the risk of interference between the protrusion portion 24221 and other components. Therefore, when 0.2 mm ≤ H2 ≤ 4.9 mm, the service life and energy density of the battery cell 20 can be considered, and the risk of interference between the protrusion portion 24221 and other components can be reduced.

[0264] Optionally, 0.3 mm ≤ H2 ≤ 3 mm.

[0265] The height of the protrusion of the protrusion portion 24221 can be: H2 = 0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, etc.

[0266] When H2 is greater than or equal to 0.3 mm, the bulging height of the bulging portion 24221 is high, so that the deformation of the bulging portion 24221 is more obvious, and under the same burst pressure, the thickness of the weak portion 2421 can be greater, which is beneficial to reduce the risk of the weak portion 2421 being damaged in advance and improve the service life of the battery cell 20. When H2 is less than or equal to 3 mm, the bulging height of the bulging portion 24221 is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery 100 or the battery cell 20, and improve the energy density of the battery 100 or the battery cell 20, on the other hand, it is beneficial to reduce the risk of interference between the bulging portion 24221 and other components. Therefore, when 0.3 mm≤H2≤3 mm, the service life and energy density of the battery cell 20 can be better balanced, and the risk of interference between the bulging portion 24221 and other components can be reduced.

[0267] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9 and FIG. 10, FIG. 10 is a sectional view of the position B-B in FIG. 9. In some embodiments, the bulging portion 24221 includes an arc-shaped portion 24221a extending along an arc-shaped trajectory. Along the extension direction of the arc-shaped trajectory, the arc-shaped portion 24221a includes a first end 24221b and a second end 24221c, and the first end 24221b and the second end 24221c are arranged along a first direction.

[0268] The arc-shaped portion 24221a is an arc-shaped structure extending along an arc-shaped trajectory. The arc-shaped trajectory can be a circular arc trajectory or a non-circular arc trajectory.

[0269] The two ends of the arc-shaped portion 24221a along the extension direction of the arc-shaped trajectory are the first end 24221b and the second end 24221c, respectively, and the first end 24221b and the second end 24221c are arranged along the first direction.

[0270] Please refer to FIG. 10, the first direction is the Z1 direction shown in the figure.

[0271] The wall with the largest surface area of the outer surface of the shell 21 is commonly referred to as a large face. Please refer to FIG. 4, the thickness direction of the large face is the Z2 direction shown in the figure.

[0272] The first direction is parallel to the thickness direction of the large face. It should be noted that here the first direction is parallel to the thickness direction of the large face, not that the first direction is completely parallel to the thickness direction of the large face, but there can be a certain angle, for example, the angle between the first direction and the thickness direction of the large face is less than or equal to 5°.

[0273] When the battery cell 20 expands, the wall of the shell 21 with the largest outer surface area deforms most. By having the protruding portion 24221 include an arc-shaped portion 24221a extending along an arc-shaped trajectory, and the first direction being parallel to the thickness direction of the wall of the shell 21 with the largest outer surface area, when the battery cell 20 expands, the protruding portion 24221 is more easily stretched under the action of an external force, thereby further reducing the pulling of the weak portion 2421 by the external force, reducing the risk of the weak portion 2421 being damaged prematurely, and helping to improve the service life of the battery cell 20.

[0274] Please refer to FIG. 11, which is a cross-sectional view of the pressure relief mechanism 24 provided by some embodiments of the present application. In some embodiments, the connecting portion 241 is a flat plate structure, and the weak portion 2421 is directly connected to the connecting portion 241 and the protruding portion 24221.

[0275] The connecting portion 241 is a flat plate structure, which means that the connecting portion 241 has no local protrusions or local recesses. In some embodiments, the connecting portion 241 is an annular structure. The connecting portion 241 is arranged around the outside of the weak portion 2421, and the weak portion 2421 is arranged around the outside of the pressure relief area 2422.

[0276] Please refer to FIG. 11, in which the weak portion 2421 is directly connected to the connecting portion 241 and the protruding portion 24221. At this time, the pressure relief area 2422 as a whole protrudes in a direction away from the electrode assembly 23 to form the protruding portion 24221.

[0277] The connecting portion 241 is a flat plate structure, which makes it more convenient to connect the connecting portion 241 to the wall portion 213. The weak portion 2421 is directly connected to the connecting portion 241 and the protruding portion 24221, and when the battery cell 20 is relieved of pressure, the protruding portion 24221 can directly pull the weak portion 2421, so that the weak portion 2421 is subjected to greater shear force, thereby facilitating the opening of the weak portion 2421 to relieve pressure. Under the same burst pressure, the thickness of the weak portion 2421 can be greater, and the weak portion 2421 is less likely to crack prematurely due to changes in internal pressure of the battery cell 20 or external impact when the battery cell 20 is in normal use, thereby reducing the risk of the weak portion 2421 being damaged prematurely and helping to improve the service life of the battery cell 20. In addition, the greater the thickness of the weak portion 2421, the easier it is to manufacture, thereby helping to improve the consistency of the burst pressure of multiple battery cells 20.

[0278] Please refer to FIG. 12, which is a cross-sectional view of the pressure relief mechanism 24 provided by some embodiments of the present application. In some embodiments, the connecting portion 241 is at least partially protruding in a direction away from the electrode assembly 23, and the weak portion 2421 is connected to the portion of the connecting portion 241 farthest from the electrode assembly 23.

[0279] The connecting portion 241 can be partially raised in a direction away from the electrode assembly 23, or the connecting portion 241 can be entirely raised in a direction away from the electrode assembly 23. The weak portion 2421 is connected to a portion of the connecting portion 241 farthest away from the electrode assembly 23.

[0280] By raising the connecting portion 241 at least partially in a direction away from the electrode assembly 23 and connecting the weak portion 2421 to a portion of the connecting portion 241 farthest away from the electrode assembly 23, the weak portion 2421 is less likely to be affected when the connecting portion 241 is connected to the wall portion 213, which helps to maintain the performance of the weak portion 2421 and improves the service life of the battery monomer 20.

[0281] Please refer to FIGS. 3, 4, 5 and 6 again. In some embodiments, the connecting portion 241 is at least partially raised in a direction facing the electrode assembly 23, and the weak portion 2421 is connected to a portion of the connecting portion 241 closest to the electrode assembly 23.

[0282] The connecting portion 241 can be partially raised in a direction facing the electrode assembly 23, or the connecting portion 241 can be entirely raised in a direction facing the electrode assembly 23. The weak portion 2421 is connected to a portion of the connecting portion 241 closest to the electrode assembly 23.

[0283] Please refer to FIG. 6. In the embodiment shown in FIG. 6, a portion of the connecting portion 241 is connected to the wall portion 213, another portion of the connecting portion 241 is raised in a direction facing the electrode assembly 23, and the weak portion 2421 is connected to the portion of the connecting portion 241 raised in a direction facing the electrode assembly 23.

[0284] The connecting portion 241 is at least partially raised in a direction facing the electrode assembly 23, and the raised portion 24221 is raised in a direction away from the electrode assembly 23. The raised direction of the connecting portion 241 and the raised direction of the raised portion 24221 are opposite, so that the raised portion 24221 can use the raised height of the connecting portion 241 to raise, thereby helping to reduce the height of the raised portion 24221 beyond the surface of the connecting portion 241 farthest away from the electrode assembly 23, reduce the occupation of the internal space of the battery monomer 20 or the battery 100, and help to improve the energy density of the battery monomer 20 or the battery 100. In addition, since the weak portion 2421 is connected to a portion of the connecting portion 241 closest to the electrode assembly 23, that is, the position of the weak portion 2421 is closer to the electrode assembly 23 than the position of the fixed point of the connecting portion 241 and the wall portion 213, and since one end of the connecting portion 241 is constrained by the wall portion 213, under the action of air pressure, the portion of the connecting portion 241 raised in a direction facing the electrode assembly 23 extrudes the weak portion 2421, thereby inhibiting the cracking of the weak portion 2421 and preventing the creep failure of the weak portion 2421 during normal operation of the battery monomer 20, effectively prolonging the service life of the battery monomer 20.

[0285] Please refer to FIG. 3, FIG. 4, FIG. 5 and FIG. 6, in some embodiments, part of the connecting portion 241 is inclined to the inside of the shell 21. In the cross section of the connecting portion 241, the angle between the inclined part of the connecting portion 241 and the thickness direction of the wall portion 213 is a, which satisfies: 30°≤a≤70°.

[0286] Part of the connecting portion 241 is inclined to the inside of the shell 21, and the part of the connecting portion 241 inclined to the inside of the shell 21 is in the shape of a tapered cylinder.

[0287] a represents the angle between the inclined part of the connecting portion 241 and the thickness direction of the wall portion 213 in the cross section of the connecting portion 241. For ease of identification, the straight line where the thickness direction of the wall portion 213 is located is shown by a dashed line in FIG. 6. When measuring, the angle between the surface of the inclined part of the connecting portion 241 facing the electrode assembly 23 and the thickness direction of the wall portion 213 can be measured as a.

[0288] In the cross section of the connecting portion 241, the angle between the inclined part of the connecting portion 241 and the thickness direction of the wall portion 213 can be: a=30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, etc.

[0289] When a≥30°, the inclination of the connecting portion 241 is large, and the constraint effect on the weak portion 2421 is good, which is conducive to reducing the risk of creep failure of the weak portion 2421. When a≤70°, the inclination of the connecting portion 241 is not too large, which is conducive to reducing stress concentration and reducing the risk of brittle fracture.

[0290] Please refer to FIG. 3, FIG. 4, FIG. 5 and FIG. 6, in some embodiments, the protrusion height of the connecting portion 241 is H3, which satisfies: 0.2mm≤H3≤7mm.

[0291] H3 represents the protrusion height of the connecting portion 241. The part of the connecting portion 241 connected with the wall portion 213 has a third surface facing the electrode assembly 23, and the inclined part of the connecting portion 241 has a fourth surface facing the electrode assembly 23. The maximum distance between the third surface and the fourth surface can be measured as H3.

[0292] The protrusion height of the connecting portion 241 can be: H3=0.2mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, etc.

[0293] When H3≥0.2mm, the protrusion height of the connecting portion 241 is large, thereby facilitating reduction of the height of the protrusion portion 24221 beyond the surface of the connecting portion 241 farthest from the electrode assembly 23, reduction of the occupation of the internal space of the battery cell 20 or the battery 100, and improvement of the energy density of the battery cell 20 or the battery 100. When H3≤7mm, the protrusion height of the connecting portion 241 is not excessively large, thereby facilitating reduction of the manufacturing difficulty and saving of the manufacturing cost. Therefore, when 0.2mm≤H3≤7mm, the occupation of the internal space of the battery cell 20 or the battery 100 by the protrusion portion 24221 can be effectively reduced, and the manufacturing cost of the battery cell 20 can be reduced.

[0294] Optionally, 0.2mm≤H3≤5mm.

[0295] The protrusion height of the connecting portion 241 can be H3=0.2mm, 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.8mm, 3mm, 3.2mm, 3.5mm, 3.8mm, 4mm, 4.2mm, 4.5mm, 4.8mm, 5mm, etc.

[0296] When H3≥0.2mm, the protrusion height of the connecting portion 241 is large, thereby facilitating reduction of the height of the protrusion portion 24221 beyond the surface of the connecting portion 241 farthest from the electrode assembly 23, reduction of the occupation of the internal space of the battery cell 20 or the battery 100, and improvement of the energy density of the battery cell 20 or the battery 100. When H3≤5mm, the protrusion height of the connecting portion 241 is not excessively large, thereby facilitating reduction of the manufacturing difficulty and saving of the manufacturing cost. Therefore, when 0.2mm≤H3≤5mm, the occupation of the internal space of the battery cell 20 or the battery 100 by the protrusion portion 24221 can be effectively reduced, and the manufacturing cost of the battery cell 20 can be reduced.

[0297] Please refer to FIG. 3, FIG. 4, FIG. 5 and FIG. 6. In some embodiments, along the thickness direction of the wall portion 213, the connecting portion 241 has a first surface 2411 farthest from the electrode assembly 23, and the protrusion portion 24221 does not exceed the first surface 2411 in the direction away from the electrode assembly 23. The first surface 2411 is the surface of the connecting portion 241 farthest from the electrode assembly 23 along the thickness direction of the wall portion 213.

[0298] When the protrusion portion 24221 does not exceed the first surface 2411 in the direction away from the electrode assembly 23, the position of the protrusion portion 24221 farthest from the electrode assembly 23 can be flush with the first surface 2411, or the position of the protrusion portion 24221 farthest from the electrode assembly 23 can be closer to the electrode assembly 23 than the first surface 2411.

[0299] By making the protruding portion 24221 not protrude beyond the first surface 2411 in the direction away from the electrode assembly 23, on the one hand, the occupation of the internal space of the battery monomer 20 or the battery 100 can be reduced, which is conducive to improving the energy density of the battery monomer 20 or the battery 100. On the other hand, the protruding portion 24221 is less likely to be affected by external forces, which is conducive to reducing the risk of the weak portion 2421 being damaged prematurely and improving the service life of the battery monomer 20.

[0300] In some other embodiments, along the thickness direction of the wall portion 213, the protruding portion 24221 does not protrude beyond the outer surface of the wall portion 213 in the direction away from the electrode assembly 23.

[0301] Along the thickness direction of the wall portion 213, the wall portion 213 has oppositely arranged inner and outer surfaces, wherein the inner surface faces the electrode assembly 23, and the outer surface faces away from the electrode assembly 23.

[0302] When the protruding portion 24221 does not protrude beyond the outer surface of the wall portion 213 in the direction away from the electrode assembly 23, the position of the protruding portion 24221 farthest away from the electrode assembly 23 can be flush with the outer surface of the wall portion 213, or the position of the protruding portion 24221 farthest away from the electrode assembly 23 can be closer to the electrode assembly 23 than the outer surface of the wall portion 213.

[0303] By making the protruding portion 24221 not protrude beyond the outer surface of the wall portion 213 in the direction away from the electrode assembly 23, on the one hand, the occupation of the internal space of the battery 100 can be reduced, which is conducive to improving the energy density of the battery 100. On the other hand, the protruding portion 24221 is less likely to interfere with other components and be affected by external forces, which is conducive to reducing the risk of the weak portion 2421 being damaged prematurely and improving the service life of the battery monomer 20.

[0304] In yet some other embodiments, along the thickness direction of the wall portion 213, the connecting portion 241 has a first surface 2411 farthest away from the electrode assembly 23, the battery monomer 20 includes an electrode terminal 25 arranged on the wall portion 213 and at least partially protruding from the outer surface of the wall portion 213. The electrode terminal 25 has a second surface 251 facing away from the electrode assembly 23. Along the thickness direction of the wall portion 213, the protruding portion 24221 protrudes beyond the first surface 2411 in the direction in which the second surface 251 points to the first surface 2411, and does not protrude beyond the second surface 251.

[0305] The electrode terminal 25 is electrically connected with the tab 232 of the electrode assembly 23 to input or output electric energy of the battery cell 20. The electrode terminal 25 can be directly connected with the tab 232, for example, the electrode terminal 25 is directly welded with the tab 232. The electrode terminal 25 can also be indirectly connected with the tab 232, for example, the electrode terminal 25 is indirectly connected with the tab 232 through a current collecting member. The electrode terminal 25 can be insulatedly arranged on the wall portion 213 and at least partially protrude from the outer surface of the wall portion 213. The electrode terminal 25 has a second surface 251 farthest away from the electrode assembly 23.

[0306] In the thickness direction of the wall portion 213, the protruding portion 24221 protrudes beyond the first surface 2411 in a direction away from the electrode assembly 23, but does not protrude beyond the second surface 251. In other words, the position of the protruding portion 24221 farthest away from the electrode assembly 23 is farther away from the electrode assembly 23 than the first surface 2411. The position of the protruding portion 24221 farthest away from the electrode assembly 23 can be flush with the second surface 251. The position of the protruding portion 24221 farthest away from the electrode assembly 23 can also be closer to the electrode assembly 23 than the second surface 251.

[0307] By making the protruding portion 24221 protrude beyond the first surface 2411 in a direction away from the electrode assembly 23, the deformation of the protruding portion 24221 is more obvious. In the case of the same burst pressure, the thickness of the weak portion 2421 can be greater, which is beneficial to reduce the risk of the weak portion 2421 being damaged in advance and improve the service life of the battery cell 20. By making the protruding portion 24221 not protrude beyond the second surface 251 in a direction away from the electrode assembly 23, it is beneficial to reduce the risk of interference between the protruding portion 24221 and other electrically connected components 241.

[0308] In still other embodiments, the battery cell 20 includes an electrode terminal 25 arranged on the wall portion 213 and at least partially protruding from the outer surface of the wall portion 213, the electrode terminal 25 has a second surface 251 away from the electrode assembly 23. In the thickness direction of the wall portion 213, the protruding portion 24221 does not protrude beyond the second surface 251 in a direction away from the inside of the shell 21.

[0309] At this time, the protruding portion 24221 can protrude beyond the first surface 2411 in a direction away from the inside of the shell 21, or can not protrude beyond the first surface 2411.

[0310] By making the protruding portion 24221 not protrude beyond the second surface 251 in a direction away from the electrode assembly 23, it is beneficial to reduce the risk of interference between the protruding portion 24221 and other electrically connected components 241.

[0311] Please refer to FIG. 3, FIG. 4, FIG. 5 and FIG. 6. In some embodiments, the battery cell 20 comprises an insulation piece 27, which is arranged between the wall portion 213 and the electrode assembly 23 along the thickness direction of the wall portion 213. The insulation piece 27 is closer to the electrode assembly 23 than the pressure relief mechanism 24 along the thickness direction of the wall portion 213.

[0312] The insulation piece 27 has insulation properties, and is arranged between the wall portion 213 and the electrode assembly 23, so as to insulate and separate the wall portion 213 and the electrode assembly 23, thereby reducing the risk of short circuit. For example, the insulation piece 27 can be plastic, rubber, etc.

[0313] In some embodiments, the wall portion 213 is the end cover 212, and the insulation piece 27 can be a lower plastic arranged between the end cover 212 and the electrode assembly 23.

[0314] In some other embodiments, the wall portion 213 is the bottom wall of the shell 211, and the insulation piece 27 can be a pad arranged between the bottom wall and the electrode assembly 23.

[0315] The insulation piece 27 is closer to the pressure relief mechanism 24 along the thickness direction of the wall portion 213, so as to reduce the risk of interference between the pressure relief mechanism 24 and the electrode assembly 23.

[0316] By arranging the insulation piece 27 between the wall portion 213 and the electrode assembly 23, the wall portion 213 and the electrode assembly 23 can be insulated and separated, thereby reducing the risk of short circuit caused by contact between the wall portion 213 and the electrode assembly 23. By making the insulation piece 27 closer to the electrode assembly 23 than the pressure relief mechanism 24, the risk of contact between the electrode assembly 23 and the pressure relief mechanism 24 can be reduced, and a fluid passage can be left between the electrode assembly 23 and the pressure relief mechanism 24, thereby facilitating pressure relief.

[0317] In some embodiments, the material of the pressure relief mechanism 24 is 304 stainless steel, 305 stainless steel or 316 stainless steel.

[0318] 304 stainless steel, 305 stainless steel and 316 stainless steel have the advantages of corrosion resistance, high temperature resistance and good processing performance. The pressure relief mechanism 24 made of 304 stainless steel, 305 stainless steel or 316 stainless steel has high strength, which can reduce the risk of deformation of the pressure relief mechanism 24 under stress, is conducive to reducing the risk of early valve opening and pressure relief of the pressure relief mechanism 24, is conducive to improving the service life and reliability of the battery cell 20, and is conducive to improving the consistency of the detonation pressure of multiple battery cells 20.

[0319] Please refer to FIG. 3, FIG. 4, FIG. 5 and FIG. 7. In some embodiments, the pressure relief mechanism 24 is provided with a pressure relief groove 245, and the position corresponding to the pressure relief groove 245 of the pressure relief mechanism 24 forms a weak portion 2421.

[0320] The pressure relief mechanism 24 has a fifth surface and a sixth surface arranged opposite in the thickness direction of the wall portion 213. The fifth surface faces the electrode assembly 23, and the sixth surface faces away from the electrode assembly 23. The sixth surface can be provided with the pressure relief groove 245, or the fifth surface can be provided with the pressure relief groove 245. Taking the case where the sixth surface is provided with the pressure relief groove 245, that is, the pressure relief groove 245 is recessed from the sixth surface toward the fifth surface, and the thin portion 2421 is the portion between the groove bottom surface of the pressure relief groove 245 and the fifth surface.

[0321] The pressure relief groove 245 can be formed in various ways, such as press forming, cold heading, and the like. Taking the case where the pressure relief groove 245 is formed by press forming, the pressure relief groove 245 can be press formed on the pressure relief mechanism 24 in the thickness direction of the wall portion 213.

[0322] The press forming or cold heading of the pressure relief groove 245 causes cold work hardening of the groove wall of the pressure relief groove 245 (change in crystal grain arrangement, resulting in distortion of the crystal lattice, reduction in metal plasticity, and increase in material hardness), which enhances the ability of the groove wall to resist external impact and makes it less likely to be damaged by external impact. This is advantageous in reducing the risk of liquid leakage from the pressure relief mechanism 24.

[0323] The thin portion 2421 is formed on the pressure relief mechanism 24 by opening the pressure relief groove 245 on the pressure relief mechanism 24, and when the battery cell 20 is relieved of pressure, the pressure relief mechanism 24 is split along at least part of the thin portion 2421, which is simple and convenient and has a low cost.

[0324] Please refer to FIGS. 8, 9, 10, and 13. FIG. 13 is an enlarged view of position C in FIG. 10. In some embodiments, the cross section of the pressure relief groove 245 is trapezoidal or conical.

[0325] When the cross section of the pressure relief groove 245 is trapezoidal or conical, it is advantageous for the pressure relief zone 2422 to open quickly when the battery cell 20 is in thermal runaway.

[0326] Please refer to FIGS. 8, 9, 10, and 13. In some embodiments, along the width direction of the pressure relief groove 245, the pressure relief groove 245 includes two groove side surfaces arranged opposite. The angle between the two groove side surfaces is b, and satisfies: 30°≤b≤90°.

[0327] Please refer to FIG. 13. The width direction of the pressure relief groove 245 is the N direction shown in the figure.

[0328] b represents the included angle between the two groove side surfaces. The included angle between the two groove side surfaces can be: b=30°, 35°, 40°, 45°, b=50°, 55°, 60°, 65°, b=70°, 75°, 80°, 85°, 90°, and the like.

[0329] When b is greater than or equal to 30°, the pressure relief groove 245 can be punched out more easily, reducing the difficulty of processing the pressure relief groove 245, and thus reducing the manufacturing cost of the battery monomer 20. When b is less than or equal to 90°, the extrusion can be reduced. Therefore, when 30°≤b≤90°, both the manufacturing cost of the battery monomer 20 and the extrusion can be reduced.

[0330] Optionally, 40°≤b≤80°.

[0331] The included angle of the two groove sides can be: b=40°, 42°, 45°, 48°, b=50°, 52°, 55°, 58°, 60°, 62°, 65°, 68°, b=70°, 72°, 75°, 78°, 80°, etc.

[0332] When b is greater than or equal to 40°, the pressure relief groove 245 can be punched out more easily, reducing the difficulty of processing the pressure relief groove 245, and thus further reducing the manufacturing cost of the battery monomer 20. When b is less than or equal to 80°, the extrusion can be further reduced. Therefore, when 40°≤b≤80°, both the manufacturing cost of the battery monomer 20 and the extrusion can be reduced.

[0333] Please refer to FIG. 8, FIG. 9, FIG. 10 and FIG. 13, in some embodiments, the weak part 2421 includes a first weak section 24212 and a second weak section 24213, the first weak section 24212 and the second weak section 24213 are connected end to end, and the thickness of the first weak section 24212 is less than the thickness of the second weak section 24213.

[0334] The first weak section 24212 plays a role of pressure relief, and is used to enable the pressure relief mechanism 24 to split along at least a part of the first weak section 24212 when the internal pressure or temperature of the battery monomer 20 reaches a predetermined value, so as to release the pressure inside the battery monomer 20.

[0335] The second weak section 24213 plays a role of guiding the at least a part of the pressure relief area 2422 to flip open. The second weak section 24213 has a higher strength than the first weak section 24212. When the battery monomer 20 is relieved, the first weak section 24212 splits first to allow the fluid medium in the battery monomer 20 to flow out for pressure relief. Then, the pressure relief area 2422 can be flipped outward with the second weak section 24213 as the rotation axis under the action of the fluid medium, so as to open a larger opening and achieve rapid pressure relief.

[0336] Please refer to FIG. 9, the first weak section 24212 includes a first section 24212a, a second section 24212b and a third section 24212c, the first section 24212a and the third section 24212c are oppositely arranged, one end of the second section 24212b is connected to one end of the first section 24212a, and the other end of the second section 24212b is connected to one end of the third section 24212c. The second weak section 24213 connects the other end of the first section 24212a and the other end of the third section 24212c. The first section 24212a, the second section 24212b, the third section 24212c and the second weak section 24213 together define a pressure relief area 2422.

[0337] By arranging the second weak section 24213, the strength of the pressure relief mechanism 24 at the position of the second weak section 24213 is weakened, so that the pressure relief area 2422 is more likely to be turned open under the action of the internal pressure of the battery monomer 20. Not only can the probability of opening of the pressure relief area 2422 be improved, but also the opening speed of the pressure relief area 2422 can be improved, realizing rapid pressure relief, reducing the risk of explosion and fire of the battery monomer 20, and being beneficial to improving the reliability of the battery monomer 20.

[0338] Please refer to FIG. 14, which is a structural schematic diagram of the pressure relief mechanism 24 provided by some embodiments of the present application. In some embodiments, along the extension direction of the second weak section 24213, the second weak section 24213 includes a third end 24213a and a fourth end 24213b, and the line connecting the third end 24213a and the fourth end 24213b is a first line. The included angle between the first line and the thickness direction of the wall with the largest surface area of the outer surface of the shell 21 is C, which satisfies: 0≤C≤45°.

[0339] The third end 24213a is one end of the second weak section 2421 along its extension direction, and the fourth end 24213b is the other end of the second weak section 24213 along its extension direction. The first line is the line connecting the third end 24213a and the fourth end 24213b.

[0340] The wall with the largest surface area of the outer surface of the shell 21 is commonly referred to as the large face. C represents the included angle between the first line and the thickness direction of the large face.

[0341] The included angle between the first line and the thickness direction of the wall with the largest surface area of the outer surface of the shell 21 can be: C=0, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, etc.

[0342] When 0≤C≤45°, the first line has a smaller included angle with the thickness direction of the wall with the largest outer surface area of the shell 21, and when the battery monomer 20 is depressurized, even if the pressure relief area 2422 is not completely opened, the high-temperature gas and / or flame sprayed out is not easy to direct to another battery monomer 20 adjacent thereto, and thermal runaway of the other battery monomer 20 is not easy to be caused, which is beneficial to improve the reliability of the battery 100.

[0343] Optionally, the first line is parallel to the thickness direction of the wall with the largest outer surface area of the shell 21.

[0344] When the first line is parallel to the thickness direction of the wall with the largest outer surface area of the shell 21, C=0.

[0345] The first line is parallel to the thickness direction of the wall with the largest outer surface area of the shell 21, and when the battery monomer 20 is depressurized, even if the pressure relief area 2422 is not completely opened, the high-temperature gas and / or flame sprayed out is not easy to direct to another battery monomer 20 adjacent thereto, and thermal runaway of the other battery monomer 20 is not easy to be caused, which is beneficial to improve the reliability of the battery 100.

[0346] Please refer to FIG. 14, in some embodiments, the second weak section 24213 extends along an arc trajectory.

[0347] The second weak section 24213 can extend along a circular arc trajectory, and the second weak section 24213 can also extend along a non-circular arc trajectory.

[0348] When the second weak section 24213 extends along an arc trajectory, the area of the pressure relief area 2422 is larger, and it is convenient to open a larger opening for pressure relief.

[0349] In other embodiments, the second weak section 24213 extends along a straight line trajectory.

[0350] When the second weak section 24213 extends along a straight line trajectory, the second weak section 24213 is a strip-shaped structure.

[0351] When the second weak section 24213 extends along a straight line trajectory, it is convenient to process and has a good guiding effect on turning over the pressure relief area 2422.

[0352] Please refer to FIG. 8, FIG. 9 and FIG. 10 again, in some embodiments, the minimum thickness of the second weak section 24213 is H4, which satisfies: 0.05mm≤H4≤0.2mm.

[0353] H4 represents the minimum thickness of the second weak section 24213 in the thickness direction of the wall portion 213, and when measuring, the thickness at different positions can be measured multiple times and the average value is taken as H4.

[0354] The minimum thickness of the second weak section 24213 along the thickness direction of the wall portion 213 can be: H4 = 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, etc.

[0355] When H4≥0.05 mm, the thickness of the second weak section 24213 is relatively large, which can reduce the risk of the second weak section 24213 cracking due to the change of the internal gas pressure of the battery monomer 20 or external impact, and is beneficial to improve the reliability of the battery monomer 20. When H4≤0.2 mm, the thickness of the second weak section 24213 is not too large, thereby being beneficial to reduce the resistance of the pressure relief area 2422 to turn over, facilitating the pressure relief area 2422 to quickly turn over and open, and being beneficial to improve the timeliness of the pressure relief of the battery monomer 20. Therefore, when 0.05 mm≤H4≤0.2 mm, the thickness of the second weak section 24213 is moderate, the second weak section 24213 is neither easy to crack due to the change of the internal gas pressure of the battery monomer 20 or external impact, nor facilitates the pressure relief area 2422 to quickly turn over and open, which is beneficial to improve the timeliness of the pressure relief of the battery monomer 20.

[0356] Optionally, 0.05 mm≤H4≤0.15 mm.

[0357] The minimum thickness of the second weak section 24213 along the thickness direction of the wall portion 213 can be: H4 = 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, etc.

[0358] When H4≥0.05 mm, the thickness of the second weak section 24213 is relatively large, which can reduce the risk of the second weak section 24213 cracking due to the change of the internal gas pressure of the battery monomer 20 or external impact, and is beneficial to improve the reliability of the battery monomer 20. When H4≤0.15 mm, the thickness of the second weak section 24213 is not too large, thereby being more beneficial to reduce the resistance of the pressure relief area 2422 to turn over, facilitating the pressure relief area 2422 to quickly turn over and open, and being more beneficial to improve the timeliness of the pressure relief of the battery monomer 20. Therefore, when 0.05 mm≤H4≤0.2 mm, the thickness of the second weak section 24213 is moderate, the second weak section 24213 is neither easy to crack due to the change of the internal gas pressure of the battery monomer 20 or external impact, nor facilitates the pressure relief area 2422 to quickly turn over and open, which is beneficial to improve the timeliness of the pressure relief of the battery monomer 20.

[0359] Please refer to FIG. 8, FIG. 9 and FIG. 10, in some embodiments, the thickness of the pressure relief mechanism 24 is H5, which satisfies: 0.05 mm≤H5≤0.5 mm.

[0360] H5 represents the thickness of the pressure relief mechanism 24. It should be noted that the thickness of the pressure relief mechanism 24 refers to the thickness of the pressure relief mechanism 24 at a non-thin position. For example, in the embodiment in which the pressure relief mechanism 24 is provided with the pressure relief groove 245, the thickness of the pressure relief mechanism 24 is the thickness of the area of the pressure relief mechanism 24 excluding the pressure relief groove 245. When measuring, the thickness can be measured multiple times and averaged as H5.

[0361] The thickness of the pressure relief mechanism 24 can be: H5 = 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, etc.

[0362] When H5≥0.05 mm, the thickness of the pressure relief mechanism 24 is large, the pressure relief mechanism 24 has high structural strength, which can reduce the risk of deformation of the pressure relief mechanism 24 under stress, and is beneficial to improve the service life and reliability of the battery monomer 20. When H5≤0.5 mm, the thickness of the pressure relief mechanism 24 is not too large, which is beneficial to control the manufacturing cost of the battery monomer 20. Therefore, when 0.05 mm≤H5≤0.5 mm, the service life, reliability and manufacturing cost of the battery monomer 20 can be considered.

[0363] Optionally, 0.05 mm≤H5≤0.3 mm.

[0364] The thickness of the pressure relief mechanism 24 can be: H5 = 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.3 mm, etc.

[0365] When H5≥0.05 mm, the thickness of the pressure relief mechanism 24 is large, the pressure relief mechanism 24 has high structural strength, which can reduce the risk of deformation of the pressure relief mechanism 24 under stress, and is beneficial to improve the service life and reliability of the battery monomer 20. When H5≤0.3 mm, the thickness of the pressure relief mechanism 24 is not too large, which is more beneficial to control the manufacturing cost of the battery monomer 20. Therefore, when 0.05 mm≤H5≤0.3 mm, the service life, reliability and manufacturing cost of the battery monomer 20 can be considered.

[0366] Please refer to FIG. 3, FIG. 4, FIG. 5 and FIG. 6 again. In some embodiments, the pressure relief mechanism 24 is located at one end of the pressure relief hole 2131 facing the electrode assembly 23.

[0367] Along the thickness direction of the wall portion 213, the pressure relief hole 2131 has two opposite ends, one end faces the electrode assembly 23, and the other end faces away from the electrode assembly 23, and the pressure relief mechanism 24 is arranged at the end of the pressure relief hole 2131 facing the electrode assembly 23.

[0368] Optionally, the battery cell 20 comprises a protection member 26, which is arranged at the end of the pressure relief hole 2131 away from the electrode assembly 23 and covers the pressure relief hole 2131.

[0369] When the pressure relief mechanism 24 is arranged at the end of the pressure relief hole 2131 facing the shell 211, the pressure relief mechanism 24 is less likely to be affected by external forces, which is conducive to reducing the risk of the pressure relief mechanism 24 opening the valve to relieve pressure in advance and improving the service life and reliability of the battery cell 20.

[0370] In some embodiments, the base material of the wall portion 213 is iron, and the pressure relief mechanism 24 is welded to the wall portion 213.

[0371] The "base material of the wall portion 213 is iron" means that the material with the largest mass percentage in the material of the wall portion 213 is iron. For example, the material of the wall portion 213 can be carbon steel or stainless steel. The carbon steel can be low-carbon steel, medium-carbon steel, or high-carbon steel. For example, the material of the wall portion 213 can be 304 stainless steel, 305 stainless steel, 316 stainless steel, etc.

[0372] The base materials of the pressure relief mechanism 24 and the wall portion 213 are both iron, which on the one hand can effectively improve the structural strength of the wall portion 213 and the pressure relief mechanism 24, reduce the risk of deformation of the wall portion 213 and the pressure relief mechanism 24 under stress, and is conducive to reducing the risk of the pressure relief mechanism 24 opening the valve to relieve pressure in advance, and improving the service life and reliability of the battery cell 20. On the other hand, the pressure relief mechanism 24 and the wall portion 213 are easier to weld, which is conducive to reducing the phenomenon of welding cracks between the pressure relief mechanism 24 and the end cover 212, thereby reducing the risk of liquid leakage of the battery cell 20 and improving the reliability of the battery cell 20.

[0373] Please refer to FIGS. 3, 4, 5, and 6. In some embodiments, the shell 21 comprises a shell 211 and an end cover 212, the shell 211 has an opening, and the end cover 212 is connected to the shell 211 and closes the opening. The end cover 212 is the wall portion 213, or the shell 211 comprises the wall portion 213.

[0374] The shell 211 comprises an integrally formed side wall and bottom wall, that is, the shell 211 is processed by an integrally forming process, such as stamping, casting, or extrusion forming, etc. In other words, the side wall and the bottom wall of the shell 211 are of an integrated structure.

[0375] The shell 211 comprises the wall portion 213, that is, the wall portion 213 is a wall of the shell 211. Exemplarily, the wall portion 213 is a bottom wall of the shell 211 arranged opposite to the end cover 212 in the thickness direction of the wall portion 213. Of course, in other embodiments, the wall portion 213 can also be a side wall of the shell 211.

[0376] It should be noted that the structure of the battery monomer 20 is not limited to this, and in some embodiments, the battery monomer 20 can also be other structures, for example, the shell 21 can include a shell 211 and an end cover 212, the inside of the shell 211 forms a containing cavity with an opening, the containing cavity is used to contain the electrode assembly 23, and the end cover 212 closes the opening, and the end cover 212 is a wall part 213.

[0377] It should be noted that the structure of the battery monomer 20 can also be various, and in some embodiments, the shell 21 can include a shell 211 and two end covers 212, the inside of the shell 211 forms a containing cavity, the containing cavity is used to contain the electrode assembly 23, the shell 211 forms an opening at both ends in the thickness direction of the wall part 213, and both openings are in communication with the containing cavity, and the two end covers 212 respectively close the two openings, and one of the two end covers 212 is a wall part 213.

[0378] The shell 211 of the shell 21 is provided with an opening at both ends in the thickness direction of the wall part 213, and the two end covers 212 respectively close the two openings, and the wall part 213 is one of the two end covers 212. The battery monomer 20 with this structure is convenient for assembling the battery monomer 20 from both ends of the shell 211, which is helpful to reduce the manufacturing difficulty and assembly difficulty of the battery monomer 20.

[0379] When the end cover 212 is the wall part 213, the pressure relief mechanism 24 is arranged on the end cover 212, which is simple and convenient to manufacture. When the shell 211 includes the wall part 213, the pressure relief mechanism 24 is arranged on one wall of the shell 211, and the fluid medium sprayed by the pressure relief mechanism 24 is not easy to act on other electrical connection structures on the end cover 212, which is helpful to reduce the risk of short circuit of the battery monomer 20.

[0380] Please refer to FIG. 8, FIG. 9, FIG. 10 and FIG. 11, the application embodiment also provides a pressure relief mechanism 24, the base material of the pressure relief mechanism 24 is iron, the pressure relief mechanism 24 includes a weak part 2421, a raised part 24221 and a connecting part 241, the weak part 2421 is configured to be at least partially destroyed when the battery monomer 20 is relieved, the weak part 2421 is annular, the raised part 24221 is located in the area surrounded by the weak part 2421, the connecting part 241 is located on the outside of the weak part 2421, the raised part 24221 is a raised structure raised in the thickness direction of the pressure relief mechanism 24, and the minimum thickness of the weak part 2421 is H1, which satisfies 0.01mm≤H1≤0.2mm.

[0381] Please refer to FIG. 10, the thickness direction of the pressure relief mechanism 24 is the Y direction shown in the figure.

[0382] The pressure relief mechanism 24 is a component for opening when the internal pressure or temperature of the battery monomer 20 reaches the burst pressure, so as to release the internal pressure of the battery monomer 20.

[0383] “the base material of the pressure relief mechanism 24 is iron” means that the material with the largest mass percentage in the material of the pressure relief mechanism 24 is iron. For example, the material of the pressure relief mechanism 24 can be carbon steel or stainless steel.

[0384] The weak portion 2421 functions as a pressure relief, and is configured to allow the pressure relief mechanism 24 to be broken along the weak portion 2421 to release the pressure inside the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value. In some embodiments, the strength of the pressure relief mechanism 24 at the position of the weak portion 2421 can be lower than the strength of the pressure relief mechanism 24 at other positions, so that the weak portion 2421 can be broken by the internal pressure when the internal pressure or temperature of the battery cell 20 reaches the predetermined value to release the pressure inside the battery cell 20. In other embodiments, the melting point of the pressure relief mechanism 24 at the position of the weak portion 2421 can be lower than the melting point of the pressure relief mechanism 24 at other positions. In this way, the weak portion 2421 can be broken by the high temperature when the internal pressure or temperature of the battery cell 20 reaches the predetermined value to release the pressure inside the battery cell 20.

[0385] The weak portion 2421 has a ring structure, and can have a circular ring shape or an elliptical ring shape. The weak portion 2421 divides the pressure relief mechanism 24 into two parts, one part being on the inner side of the weak portion 2421 and the other part being on the outer side of the weak portion 2421. The protruding portion 24221 is on the inner side of the weak portion 2421, and is a protruding structure protruding in the thickness direction of the pressure relief mechanism 24. The protruding structure is a structure in which the inner surface and the outer surface are both arched in the thickness direction of the pressure relief mechanism 24. The connecting portion 241 is on the outer side of the weak portion 2421, and is a portion of the pressure relief mechanism 24 for connecting the wall portion 213, for example, the connecting portion 241 can be welded to the wall portion 213.

[0386] H1 represents the minimum thickness of the weak portion 2421 in the thickness direction of the pressure relief mechanism 24, and when measuring, the thickness at different positions can be measured multiple times and the average value is taken as H1. The minimum thickness of the weak portion 2421 in the thickness direction of the pressure relief mechanism 24 can be: H1 = 0.01 mm, 0.02 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, etc.

[0387] The existing pressure relief mechanism 24 is gradually arched away from the electrode assembly 23 under the action of the internal pressure of the battery monomer 20 when pressure relief, and then opens under the action of the internal pressure of the battery monomer 20. In the embodiment of the application, the raised portion 24221 of the pressure relief mechanism 24 is raised away from the electrode assembly 23, and the raised portion 24221 forms a pre-deformation on the inner side of the weak portion 2421, thereby facilitating the cracking of the weak portion 2421 for pressure relief. In this way, under the same burst pressure, the thickness of the weak portion 2421 can be larger, and the weak portion 2421 is not easily cracked in advance due to changes in the internal pressure of the battery monomer 20 or external impact, which is beneficial to reduce the risk of the weak portion 2421 being damaged in advance and improve the service life of the battery monomer 20. When H1≥0.01mm, the thickness of the weak portion 2421 is larger, and the weak portion 2421 is not easily cracked in advance due to changes in the internal pressure of the battery monomer 20 or external impact, which is beneficial to reduce the risk of the weak portion 2421 being damaged in advance and improve the service life of the battery monomer 20. When H1≤0.2mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can open in time for pressure relief when the battery monomer 20 is out of control, which is beneficial to improve the timeliness of the pressure relief mechanism 24. Therefore, when 0.01mm≤H1≤0.2mm, the service life of the battery monomer 20 and the timeliness of pressure relief can be considered. In addition, the base material of the pressure relief mechanism 24 is iron, which can effectively improve the structural strength of the pressure relief mechanism 24, reduce the risk of deformation of the pressure relief mechanism 24 under stress, reduce the risk of the pressure relief mechanism 24 opening the valve for pressure relief in advance, and improve the service life and reliability of the battery monomer 20. Compared with the aluminum material explosion-proof valve in the prior art, the thickness of the weak portion 2421 of the pressure relief mechanism 24 provided in the embodiment of the application is smaller, and a little change in the thickness of the weak portion 2421 will cause a great change in the burst pressure of the battery monomer 20 during manufacturing. By providing the raised portion 24221, the thickness of the weak portion 2421 can be increased under the same burst pressure, and the larger the thickness of the weak portion 2421, the easier it is to manufacture, thereby improving the consistency of the burst pressure of the plurality of battery monomers 20.

[0388] Please refer to FIG. 8, FIG. 9, FIG. 10 and FIG. 11, in some embodiments, the area enclosed by the weak portion 2421 is the pressure relief area 2422. The projection area of the pressure relief area 2422 along the thickness direction of the pressure relief mechanism 24 is S. Wherein, 100mm 2 ≤S≤450mm 2 , and 0.010mm≤H1≤0.160mm; or,

[0389] 350mm 2 ≤S≤850mm 2and 0.015mm≤H1≤0.170mm; or,

[0390] 750mm 2 ≤S≤1250mm 2 and 0.020mm≤H1≤0.180mm; or,

[0391] 1150mm 2 ≤S≤1650mm 2 and 0.025mm≤H1≤0.190mm; or,

[0392] 1550mm 2 ≤S≤2100mm 2 and 0.030mm≤H1≤0.200mm.

[0393] The pressure relief area 2422 is an area of the pressure relief mechanism 24 enclosed by the weakened portion 2421, i.e. an area of the pressure relief mechanism 24 inside the weakened portion 2421.

[0394] The pressure relief area 2422 includes the above-mentioned raised portion 24221. For example, the pressure relief area 2422 can be locally raised in a direction away from the electrode assembly 23 to form the raised portion 24221, or the pressure relief area 2422 can be wholly raised in a direction away from the electrode assembly 23 to form the raised portion 24221. Please refer to FIG. 6, in the embodiment shown in FIG. 6, the pressure relief area 2422 is wholly raised in a direction away from the electrode assembly 23 to form the raised portion 24221, in this case, the pressure relief area 2422 is the raised portion 24221.

[0395] S represents the projected area of the pressure relief area 2422 in the thickness direction of the wall portion 213. Please refer to FIG. 9, in FIG. 9, S is marked with a mesh line. It should be noted that the mesh line here is only to facilitate the display of S, and does not represent any physical meaning.

[0396] The projected area of the pressure relief area 2422 in the thickness direction of the wall portion 213 can be: S=100mm 2 , 150mm 2 , 200mm 2 , 250mm 2 , 300mm 2 , 350mm 2 , 400mm 2 , 450mm 2 , 500mm 2 , 550mm 2 , 600mm 2 , 650mm 2 , 700mm 2 , 750mm 2 , 800mm2 850 mm 2 900 mm 2 950 mm 2 1000 mm 2 1050 mm 2 1100 mm 2 1150 mm 2 1200 mm 2 1250 mm 2 1300 mm 2 1350 mm 2 1400 mm 2 1450 mm 2 1500 mm 2 1550 mm 2 1600 mm 2 1650 mm 2 1700 mm 2 1750 mm 2 1800 mm 2 1850 mm 2 1900 mm 2 1950 mm 2 2000 mm 2 2050 mm 2 2100 mm 2 etc.

[0397] When 100 mm 2 ≤ S ≤ 450 mm 2 , 0.010 mm ≤ H1≤ 0.160 mm. When 100 mm 2 ≤ S ≤ 450 mm 2 , the minimum thickness of the weak portion 2421 in the thickness direction of the wall portion 213 can be: 0.010 mm, 0.020 mm, 0.030 mm, 0.040 mm, 0.050 mm, 0.060 mm, 0.070 mm, 0.080 mm, 0.090 mm, 0.100 mm, 0.110 mm, 0.120 mm, 0.130 mm, 0.140 mm, 0.150 mm, 0.160 mm, etc.

[0398] When the projection area of the pressure relief area 2422 is large, the pressure relief area 2422 is more likely to be affected by the internal pressure and cause the weak portion 2421 to crack, and therefore, when the projection area of the pressure relief area 2422 is increased, the thickness of the weak portion 2421 can be increased to ensure the same burst pressure. When 100 mm 2 ≤ S ≤ 450 mm 2, and H1≥0.010mm, the thickness of the weak portion 2421 is large, the weak portion 2421 is not easy to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, which is beneficial to reduce the risk of the weak portion 2421 being damaged in advance, and is beneficial to improve the service life of the battery monomer 20. When 100mm 2 ≤S≤450mm 2 , and H1≤0.160mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 100mm 2 ≤S≤450mm 2 , and 0.010mm≤H1≤0.160mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be considered.

[0399] When 350mm 2 ≤S≤850mm 2 , 0.015mm≤H1≤0.170mm. When 350mm 2 ≤S≤850mm 2 , the minimum thickness of the weak portion 2421 along the thickness direction of the wall portion 213 can be: H1=0.015mm, 0.020mm, 0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, 0.170mm, etc.

[0400] When 350mm 2 ≤S≤850mm 2 , and H1≥0.015mm, the thickness of the weak portion 2421 is large, the weak portion 2421 is not easy to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, which is beneficial to reduce the risk of the weak portion 2421 being damaged in advance, and is beneficial to improve the service life of the battery monomer 20. When 350mm 2 ≤S≤850mm 2 , and H1≤0.170mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be considered.

[0401] When 750mm2 ≤S≤1250mm 2 When 0.020mm ≤ H1 ≤ 0.180mm. When 750mm 2 ≤S≤1250mm 2 When the weak part 2421 has a minimum thickness along the thickness direction of the wall part 213, it can be: H1 = 0.020mm, 0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, 0.170mm, 0.180mm, etc.

[0402] When 750mm 2 ≤S≤1250mm 2 When H1 ≥ 0.020 mm, the thickness of the weak part 2421 is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 2421 and improves the lifespan of the battery cell 20. When 750 mm... 2 ≤S≤1250mm 2 When H1 ≤ 0.180 mm, the thickness of the weak part 2421 will not be too large, allowing the pressure relief mechanism 24 to open and relieve pressure in a timely manner when the battery cell 20 experiences thermal runaway, thus improving the timeliness of pressure relief by the pressure relief mechanism 24. Therefore, when 750 mm 2 ≤S≤1250mm 2 When 0.020mm≤H1≤0.180mm, the lifespan of the battery cell 20 and the timeliness of pressure relief can be taken into account.

[0403] When 1150mm 2 ≤S≤1650mm 2 When 0.025mm ≤ H1 ≤ 0.190mm. When 1150mm 2 ≤S≤1650mm 2 When the weak part 2421 has a minimum thickness along the thickness direction of the wall part 213, it can be: H1 = 0.025mm, 0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, 0.170mm, 0.180mm, 0.190mm, etc.

[0404] When 1150mm 2 ≤S≤1650mm2 When 1150mm 2 ≤S≤1650mm 2 , and H1≤0.190mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is out of control, which is conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.025mm≤H1≤0.190mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be considered.

[0405] When 1550mm 2 ≤S≤2100mm 2 , 0.030mm≤H1≤0.200mm. When 1550mm 2 ≤S≤2100mm 2 , the minimum thickness of the weak portion 2421 along the thickness direction of the wall portion 213 can be: H1=0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, 0.170mm, 0.180mm, 0.190mm, 0.200mm, etc.

[0406] When 1550mm 2 ≤S≤2100mm 2 , and H1≥0.030mm, the thickness of the weak portion 2421 is large, and the weak portion 2421 is not easy to crack in advance due to the change of the pressure inside the battery monomer 20 or the external impact, which is conducive to reducing the risk of the weak portion 2421 being damaged in advance, and is conducive to improving the service life of the battery monomer 20. When 1550mm 2 ≤S≤2100mm 2 , and H1≤0.200mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is out of control, which is conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.030mm≤H1≤0.200mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be considered.

[0407] In some embodiments, 100 mm 2 ≤ S ≤ 450 mm 2 and 0.020 mm ≤ H1≤ 0.160 mm; or,

[0408] 350 mm 2 ≤ S ≤ 850 mm 2 and 0.025 mm ≤ H1≤ 0.170 mm; or,

[0409] 750 mm 2 ≤ S ≤ 1250 mm 2 and 0.030 mm ≤ H1≤ 0.180 mm; or,

[0410] 1150 mm 2 ≤ S ≤ 1650 mm 2 and 0.035 mm ≤ H1≤ 0.190 mm; or,

[0411] 1550 mm 2 ≤ S ≤ 2100 mm 2 and 0.040 mm ≤ H1≤ 0.200 mm.

[0412] When 100 mm 2 ≤ S ≤ 450 mm 2 , 0.020 mm ≤ H1≤ 0.160 mm. When 100 mm 2 ≤ S ≤ 450 mm 2 , the minimum thickness of the weak portion 2421 in the thickness direction of the wall portion 213 can be 0.020 mm, 0.025 mm, 0.030 mm, 0.035 mm, 0.040 mm, 0.045 mm, 0.050 mm, 0.055 mm, 0.060 mm, 0.065 mm, 0.070 mm, 0.075 mm, 0.080 mm, 0.085 mm, 0.090 mm, 0.095 mm, 0.100 mm, 0.105 mm, 0.110 mm, 0.115 mm, 0.120 mm, 0.125 mm, 0.130 mm, 0.135 mm, 0.140 mm, 0.145 mm, 0.150 mm, 0.155 mm, 0.160 mm, or the like.

[0413] When 100 mm 2 ≤ S ≤ 450 mm 2, and H1 is greater than or equal to 0.020 mm, the thickness of the weak portion 2421 is greater, the weak portion 2421 is less likely to be prematurely cracked due to changes in pressure inside the battery monomer 20 or external impact, and it is more beneficial to reduce the risk of the weak portion 2421 being prematurely damaged, and it is more beneficial to improve the service life of the battery monomer 20. When 100 mm 2 ≤ S ≤ 450 mm 2 , and H1 is less than or equal to 0.160 mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can open the pressure relief more timely when the battery monomer 20 is out of control, and it is more beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 100 mm 2 ≤ S ≤ 450 mm 2 , and 0.020 mm ≤ H1 ≤ 0.160 mm, the service life and pressure relief timeliness of the battery monomer 20 can be considered.

[0414] When 350 mm 2 ≤ S ≤ 850 mm 2 , 0.025 mm ≤ H1 ≤ 0.170 mm. When 350 mm 2 ≤ S ≤ 850 mm 2 , the minimum thickness of the weak portion 2421 along the thickness direction of the wall portion 213 can be: H1 = 0.025 mm, 0.030 mm, 0.035 mm, 0.040 mm, 0.045 mm, 0.050 mm, 0.055 mm, 0.060 mm, 0.065 mm, 0.070 mm, 0.075 mm, 0.080 mm, 0.085 mm, 0.090 mm, 0.095 mm, 0.100 mm, 0.105 mm, 0.110 mm, 0.105 mm, 0.110 mm, 0.115 mm, 0.120 mm, 0.125 mm, 0.130 mm, 0.135 mm, 0.140 mm, 0.145 mm, 0.150 mm, 0.155 mm, 0.160 mm, 0.165 mm, 0.170 mm, etc.

[0415] When 350 mm 2 ≤ S ≤ 850 mm 2 , and H1 is greater than or equal to 0.025 mm, the thickness of the weak portion 2421 is greater, the weak portion 2421 is less likely to be prematurely cracked due to changes in pressure inside the battery monomer 20 or external impact, and it is more beneficial to reduce the risk of the weak portion 2421 being prematurely damaged, and it is more beneficial to improve the service life of the battery monomer 20. When 350 mm 2 ≤ S ≤ 850 mm 2, and H1≤0.170mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can be opened more timely when the battery cell 20 is in thermal runaway, which is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 350mm 2 ≤S≤850mm 2 , and 0.025mm≤H1≤0.170mm, the service life of the battery cell 20 and the timeliness of pressure relief can be better balanced.

[0416] When 750mm 2 ≤S≤1250mm 2 , 0.030mm≤H1≤0.180mm. When 750mm 2 ≤S≤1250mm 2 , the minimum thickness of the weak portion 2421 along the thickness direction of the wall portion 213 can be: H1=0.030mm, 0.035mm, 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm, 0.080mm, 0.085mm, 0.090mm, 0.095mm, 0.100mm, 0.105mm, 0.110mm, 0.115mm, 0.120mm, 0.125mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.155mm, 0.160mm, 0.165mm, 0.170mm, 0.175mm, 0.180mm, etc.

[0417] When 750mm 2 ≤S≤1250mm 2 , and H1≥0.030mm, the thickness of the weak portion 2421 is larger, and the weak portion 2421 is less likely to be prematurely cracked due to changes in internal pressure of the battery cell 20 or external impact, which is more conducive to reducing the risk of premature damage of the weak portion 2421 and improving the service life of the battery cell 20. When 750mm 2 ≤S≤1250mm 2 , and H1≤0.180mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can be opened more timely when the battery cell 20 is in thermal runaway, which is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 750mm 2 ≤S≤1250mm 2 , and 0.030mm≤H1≤0.180mm, the service life of the battery cell 20 and the timeliness of pressure relief can be better balanced.

[0418] When 1150mm 2≤S≤1650mm 2 When 1150mm 2 ≤S≤1650mm 2 mm, 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm, 0.080mm, 0.085mm, 0.090mm, 0.095mm, 0.100mm, 0.105mm, 0.110mm, 0.115mm, 0.120mm, 0.125mm, 0.130mm, 0.125mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.155mm, 0.160mm, 0.165mm, 0.170mm, 0.175mm, 0.180mm, 0.185mm, 0.190mm, etc.

[0419] When 1150mm 2 ≤S≤1650mm 2 mm, the thickness of the weak portion 2421 is greater, the weak portion 2421 is less likely to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, and it is more conducive to reducing the risk of the weak portion 2421 being damaged in advance, and more conducive to improving the service life of the battery monomer 20. When 1150mm 2 ≤S≤1650mm 2 mm, the thickness of the weak portion 2421 is not too large, so that the pressure relief mechanism 24 can open the pressure relief more timely when the battery monomer 20 is out of control, and it is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 1550mm 2 ≤S≤2100mm 2 mm, it can better balance the service life and pressure relief timeliness of the battery monomer 20.

[0420] When 1550mm 2 ≤S≤2100mm 2 mm. When 1550mm 2 ≤S≤2100mm 2When the thin part 2421 has a minimum thickness along the thickness direction of the wall part 213, it can be: H1 = 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm, 0.080mm, 0.085mm, 0.090mm, 0.095mm, 0.100mm, 0.105mm, 0.110mm, 0.115mm, 0.120mm, 0.12 5mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.125mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.155mm, 0.160mm, 0.165mm, 0.170mm, 0.175mm, 0.180mm, 0.185mm, 0.190mm, 0.195mm, 0.200mm, etc.

[0421] When 1550mm 2 ≤S≤2100mm 2 When H1 ≥ 0.040 mm, the thickness of the weak part 2421 is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 2421 and improves the lifespan of the battery cell 20. When 1550 mm... 2 ≤S≤2100mm 2 When H1 ≤ 0.200 mm, the thickness of the weak part 2421 will not be too large, allowing the pressure relief mechanism 24 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 1550 mm 2 ≤S≤2100mm 2 Furthermore, when 0.040mm≤H1≤0.200mm, it is better able to balance the service life of the battery cell 20 and the timeliness of pressure relief.

[0422] Please refer to Figures 3, 4, 5, 6 and 7. The height of the raised part 24221 is H2, which satisfies: 0.2mm≤H2≤4.9mm.

[0423] H2 represents the height of the raised portion 24221. The height of the raised portion 24221 can be: H2 = 0.2mm, 0.25, 0.3, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 4.9mm, etc.

[0424] When H2 is greater than or equal to 0.2 mm, the bulging height of the bulging part 24221 is high, so that the deformation of the bulging part 24221 is more obvious, and in the case of the same burst pressure, the thickness of the weak part 2421 is larger, which is beneficial to reduce the risk of the weak part 2421 being damaged in advance and improve the service life of the battery monomer 20. When H2 is less than or equal to 4.9 mm, the bulging height of the bulging part 24221 is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery 100 or the battery monomer 20 and improve the energy density of the battery 100 or the battery monomer 20, and on the other hand, it is beneficial to reduce the risk of interference between the bulging part 24221 and other components. Therefore, when 0.2 mm≤H2≤4.9 mm, the service life and the energy density of the battery monomer 20 can be considered, and the risk of interference between the bulging part 24221 and other components can be reduced.

[0425] Optionally, 0.3 mm≤H2≤3 mm.

[0426] The bulging height of the bulging part 24221 can be: H2=0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, etc.

[0427] When H2 is greater than or equal to 0.3 mm, the bulging height of the bulging part 24221 is high, so that the deformation of the bulging part 24221 is more obvious, and in the case of the same burst pressure, the thickness of the weak part 2421 can be larger, which is beneficial to reduce the risk of the weak part 2421 being damaged in advance and improve the service life of the battery monomer 20. When H2 is less than or equal to 3 mm, the bulging height of the bulging part 24221 is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery 100 or the battery monomer 20 and improve the energy density of the battery 100 or the battery monomer 20, and on the other hand, it is beneficial to reduce the risk of interference between the bulging part 24221 and other components. Therefore, when 0.3 mm≤H2≤3 mm, the service life and the energy density of the battery monomer 20 can be considered, and the risk of interference between the bulging part 24221 and other components can be reduced.

[0428] The application also provides a battery 100, which comprises the battery monomer 20 described above.

[0429] In some embodiments, the battery 100 includes a plurality of battery cells 20 arranged along a second direction. The second weak portion 2421 includes a first weak section 24212 and a second weak section 24213 connected end to end, the first weak section 24212 having a thickness smaller than that of the second weak section 24213. Along an extension direction of the second weak section 24213, the second weak section 24213 includes a third end 24213a and a fourth end 24213b, a line connecting the third end 24213a and the fourth end 24213b being a first line, an angle between the first line and the second direction being D, satisfying: 0≤D≤45°.

[0430] The battery 100 can include two battery cells 20, three battery cells 20, four battery cells 20, or more battery cells 20. The plurality of battery cells 20 are arranged along a second direction.

[0431] The first weak section 24212 functions as a pressure relief, for enabling the pressure relief mechanism 24 to split along at least a portion of the first weak section 24212 when an internal pressure or temperature of the battery cell 20 reaches a predetermined value, to release the pressure inside the battery cell 20. The second weak section 24213 functions to guide at least a portion of the pressure relief area 2422 to flip open. The second weak section 24213 has a higher strength than the first weak section 24212. When the battery cell 20 is relieved of pressure, the first weak section 24212 splits first to allow the fluid medium inside the battery cell 20 to flow out for pressure relief. Subsequently, the pressure relief area 2422 can flip outward about the second weak section 24213 under the action of the fluid medium, to open a larger opening, to achieve rapid pressure relief.

[0432] The third end 24213a is one end of the second weak portion 2421 along its extension direction, and the fourth end 24213b is the other end of the second weak section 24213 along its extension direction. The first line is a line connecting the third end 24213a and the fourth end 24213b.

[0433] D represents an angle between the first line and the second direction. The angle between the first line and the second direction can be: D=0, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, etc.

[0434] When 0≤D≤45°, the angle between the first line and the second direction is small, and when the battery cell 20 is relieved of pressure, even if the pressure relief area 2422 is not fully opened, the high-temperature gas and / or flame ejected is not easy to direct towards another battery cell 20 adjacent thereto, and is not easy to cause thermal runaway of the other battery cell 20, which is beneficial to improve the reliability of the battery 100.

[0435] Optionally, the first line is parallel to the second direction.

[0436] D = 0 when the first line is parallel to the second direction.

[0437] The first line is parallel to the second direction, when the battery monomer 20 is depressurized, even if the depressurization area 2422 is not completely opened, the high-temperature gas and / or flame sprayed is not easy to be directed to another battery monomer 20 adjacent to it, and is not easy to cause another battery monomer 20 to be in thermal runaway, which is beneficial to improve the reliability of the battery 100.

[0438] In some embodiments, the second direction is the thickness direction of the wall with the largest outer surface area of the shell 21.

[0439] By arranging a plurality of battery monomers 20 along the thickness direction of the wall with the largest outer surface area of the shell 21, it is beneficial to make full use of the space and improve the energy density of the battery 100.

[0440] The embodiments of the present application also provide a power-using device, which comprises the battery monomer 20 described above, and the battery monomer 20 is used to provide electric energy for the power-using device.

[0441] According to some embodiments of the present application, please refer to FIG. 3-6.

[0442] The embodiment of the present application provides a battery monomer 20, the battery monomer 20 includes shell 21, electrode assembly 23 and pressure relief mechanism 24, shell 21 has wall portion 213, wall portion 213 is provided with pressure relief hole 2131, electrode assembly 23 is contained in shell 21, and pressure relief mechanism 24 covers pressure relief hole 2131.The base material of pressure relief mechanism 24 is iron, and pressure relief mechanism 24 includes weak portion 2421, protruding portion 24221 and connecting portion 241, weak portion 2421 is configured to be at least partially destroyed to release pressure when the pressure inside shell 21 reaches a threshold value, weak portion 2421 is annular, protruding portion 24221 is located in the area surrounded by weak portion 2421, and connecting portion 241 is located outside weak portion 2421 and connects wall portion 213.Protruding portion 24221 is a protruding structure that protrudes in a direction away from electrode assembly 23, and the minimum thickness H1 of weak portion 2421 satisfies 0.01mm≤H1≤0.2mm.The existing pressure relief mechanism 24 gradually arches away from electrode assembly 23 under the action of the pressure inside the battery monomer 20 when pressure relief, and then opens the pressure relief under the action of the pressure inside the battery monomer 20 after arching.In the embodiment of the present application, protruding portion 24221 of pressure relief mechanism 24 protrudes in a direction away from electrode assembly 23, and protruding portion 24221 forms a pre-deformation on the inside of weak portion 2421, thereby facilitating the cracking of weak portion 2421 for pressure relief.In this way, under the same burst pressure, the thickness of weak portion 2421 can be greater, and weak portion 2421 is less likely to crack prematurely due to changes in the pressure inside the battery monomer 20 or external impact, which helps to reduce the risk of weak portion 2421 being damaged prematurely and helps to improve the service life of the battery monomer 20.When H1≥0.01mm, the thickness of weak portion 2421 is greater, and weak portion 2421 is less likely to crack prematurely due to changes in the pressure inside the battery monomer 20 or external impact, which helps to reduce the risk of weak portion 2421 being damaged prematurely and helps to improve the service life of the battery monomer 20.When H1≤0.2mm, the thickness of weak portion 2421 is not too large, so that pressure relief mechanism 24 can timely open for pressure relief when the battery monomer 20 is out of control, which helps to improve the timeliness of pressure relief of pressure relief mechanism 24.Therefore, when 0.01mm≤H1≤0.2mm, the service life of the battery monomer 20 and the timeliness of pressure relief can be considered.In addition, the base material of the pressure relief mechanism 24 is iron, which can effectively improve the structural strength of the pressure relief mechanism 24, reduce the risk of deformation of the pressure relief mechanism 24 under stress, help to reduce the risk of the pressure relief mechanism 24 opening the valve for pressure relief prematurely, and help to improve the service life and reliability of the battery monomer 20.Compared with the aluminum material explosion-proof valve in the prior art, the thickness of the weak portion 2421 of the pressure relief mechanism 24 provided in the embodiment of the present application is small, and when the weak portion 2421 is manufactured, a little change in the thickness of the weak portion 2421 will cause a great change in the burst pressure of the battery monomer 20. By arranging the protruding portion 24221, the thickness of the weak portion 2421 can be increased under the condition of the same burst pressure, and the greater the thickness of the weak portion 2421 is, the easier the weak portion 2421 is to manufacture, thereby being beneficial to improving the consistency of the burst pressures of the plurality of battery monomers 20.

[0443] The area enclosed by the weak portion 2421 is the pressure relief area 2422, and the projection area of the pressure relief area 2422 in the thickness direction of the wall portion 213 is S;

[0444] 100mm 2 ≤S≤450mm 2 , and 0.010mm≤H1≤0.160mm; or,

[0445] 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm; or,

[0446] 750mm 2 ≤S≤1250mm 2 , and 0.020mm≤H1≤0.180mm; or,

[0447] 1150mm 2 ≤S≤1650mm 2 , and 0.025mm≤H1≤0.190mm; or,

[0448] 1550mm 2 ≤S≤2100mm 2 , and 0.030mm≤H1≤0.200mm.

[0449] The above merely provides the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, wherein, The application relates to a battery, comprising: a shell having a wall portion provided with a pressure relief hole; an electrode assembly accommodated in the shell; a pressure relief mechanism covering the pressure relief hole, a base material of the pressure relief mechanism being iron, the pressure relief mechanism comprising a weak portion, a raised portion and a connecting portion, the weak portion being configured to be at least partially destroyed to release pressure when the pressure inside the shell reaches a threshold value, the weak portion being annular, the raised portion being located in an area enclosed by the weak portion, and the connecting portion being located outside the weak portion and connected to the wall portion, the raised portion being a raised structure raised in a direction away from the electrode assembly, a minimum thickness of the weak portion being H1, satisfying 0.01mm<=H1<=0.2mm.

2. The battery cell of claim 1, wherein, A boundary of the raised portion at least partially abuts a boundary of the weak portion.

3. The battery cell of claim 2, wherein, The boundary of the raised portion completely abuts the boundary of the weak portion.

4. The battery cell of any one of claims 1-3, wherein, The area enclosed by the weak portion is a pressure relief area, and a projection area of the pressure relief area along a thickness direction of the wall portion is S. 100 mm 2 ≤ 450 mm 2 and 0.010 mm ≤ H1≤ 0.160 mm; or, 350 mm 2 ≤ S ≤ 850 mm 2 and 0.015 mm ≤ H1 ≤ 0.170 mm; or, 750 mm 2 ≤ S ≤ 1250 mm 2 and 0.020 mm ≤ H1 ≤ 0.180 mm; or, 1150 mm 2 ≤ S ≤ 1650 mm 2 and 0.025 mm ≤ H1 ≤ 0.190 mm; or, 1550 mm 2 ≤ S ≤ 2100 mm 2 and 0.030 mm ≤ H1 ≤ 0.200 mm.

5. The battery cell of claim 4, wherein, 100 mm 2 ≤ S ≤ 450 mm 2 and 0.020 mm ≤ H1 ≤ 0.160 mm; or, 350 mm 2 ≤ S ≤ 850 mm 2 and 0.025 mm ≤ H1 ≤ 0.170 mm; or, 750 mm 2 ≤ S ≤ 1250 mm 2 and 0.030 mm ≤ H1 ≤ 0.180 mm; or, 1150 mm 2 ≤ S ≤ 1650 mm 2 and 0.035 mm ≤ H1 ≤ 0.190 mm; or, 1550 mm 2 ≤ S ≤ 2100 mm 2 and 0.040 mm ≤ H1 ≤ 0.200 mm.

6. The battery cell of any one of claims 1-5, wherein, A raised height of the raised portion is H2, satisfying 0.2mm<=H2<=4.9mm.

7. The battery cell of claim 6, wherein, 0.3mm<=H2<=3mm.

8. The battery cell of any one of claims 1-7, wherein, The raised portion comprises an arc-shaped portion extending along an arc-shaped track, the arc-shaped portion comprising a first end and a second end arranged along a first direction, the first direction being parallel to a thickness direction of a wall with a largest outer surface area of the shell.

9. The battery cell of any one of claims 1-8, wherein, The connecting portion is a flat plate structure, and the weak portion is directly connected to the connecting portion and the raised portion.

10. The battery cell of any one of claims 1-8, wherein, The connecting portion is at least partially raised in a direction away from the electrode assembly, and the weak portion is connected to a portion of the connecting portion farthest away from the electrode assembly.

11. The battery cell of any one of claims 1-8, wherein, The connecting portion is at least partially raised in a direction facing the electrode assembly, and the weak portion is connected to a portion of the connecting portion closest to the electrode assembly.

12. The battery cell of claim 11, wherein, A portion of the connecting portion is inclined towards the inside of the shell. In a cross section of the connecting portion, an included angle between the inclined portion of the connecting portion and a thickness direction of the wall portion is a, satisfying 30<=a<=70.

13. The battery cell of any one of claims 11-12, wherein, A raised height of the connecting portion is H3, satisfying 0.2mm<=H3<=7mm, and optionally, 0.2mm<=H3<=5mm.

14. The battery cell of any one of claims 11-13, wherein, Along the thickness direction of the wall portion, the connecting portion has a first surface farthest away from the electrode assembly, and the raised portion does not exceed the first surface in the direction away from the electrode assembly.

15. The battery cell of any one of claims 1-13, wherein, Along the thickness direction of the wall portion, the raised portion does not exceed an outer surface of the wall portion in the direction away from the electrode assembly.

16. The battery cell of any one of claims 1-13, wherein, Along the thickness direction of the wall portion, the connecting portion has a first surface farthest away from the electrode assembly, and the battery monomer comprises an electrode terminal arranged on the wall portion and at least partially protruding from an outer surface of the wall portion, the electrode terminal having a second surface away from the electrode assembly. Along the thickness direction of the wall portion, the raised portion exceeds the first surface in the direction away from the electrode assembly, and does not exceed the second surface.

17. The battery cell of any one of claims 1-13, wherein, The battery cell comprises an electrode terminal provided on the wall portion and at least partially protruding from an outer surface of the wall portion, the electrode terminal having a second surface facing away from the electrode assembly; In a thickness direction of the wall portion, the protruding portion does not exceed the second surface in a direction facing away from the electrode assembly.

18. The battery cell of any one of claims 1-17, wherein, The battery cell comprises an insulating member provided between the wall portion and the electrode assembly in a thickness direction of the wall portion; In the thickness direction of the wall portion, the insulating member is closer to the electrode assembly than the pressure relief mechanism.

19. The battery cell of any one of claims 1-18, wherein, The pressure relief mechanism is made of 304 stainless steel, 305 stainless steel or 316 stainless steel.

20. The battery cell of any one of claims 1-19, wherein, The pressure relief mechanism is provided with a pressure relief groove, and the pressure relief mechanism and the pressure relief groove correspond to the weak portion.

21. The battery cell of claim 20, wherein, The pressure relief groove has a trapezoidal or conical cross section.

22. The battery cell of claim 20 or 21, wherein, In a width direction of the pressure relief groove, the pressure relief groove comprises two oppositely arranged groove side surfaces, and the angle between the two groove side surfaces is b, which satisfies 30°≤b≤90°, and optionally, 40°≤b≤80°.

23. The battery cell of any one of claims 1-22, wherein, The weak portion comprises a first weak segment and a second weak segment, the first weak segment and the second weak segment are connected end to end, and the thickness of the first weak segment is less than the thickness of the second weak segment.

24. The battery cell of claim 23, wherein, In an extension direction of the second weak segment, the second weak segment comprises a third end and a fourth end, and the line connecting the third end and the fourth end is a first line, and the included angle between the first line and the thickness direction of the wall with the largest outer surface area of the shell is C, which satisfies 0≤C≤45°.

25. The battery cell of claim 24, wherein, The first line is parallel to the thickness direction of the wall with the largest outer surface area of the shell.

26. The battery cell of claim 24 or 25, wherein, The second weak segment extends along an arc trajectory.

27. The battery cell of claim 24 or 25, wherein, The second weak segment extends along a straight line trajectory.

28. The battery cell of any one of claims 23-27, wherein, The minimum thickness of the second weak segment is H4, which satisfies 0.05mm≤H4≤0.2mm, and optionally, 0.05mm≤H4≤0.15mm.

29. The battery cell of any one of claims 1-28, wherein, The thickness of the pressure relief mechanism is H5, which satisfies 0.05mm≤H5≤0.5mm, and optionally, 0.05mm≤H5≤0.3mm.

30. The battery cell of any one of claims 1-29, wherein, The base material of the wall portion is iron, and the pressure relief mechanism is welded to the wall portion.

31. A pressure relief mechanism for a battery cell, wherein, The base material of the pressure relief mechanism is iron, the pressure relief mechanism comprises a weak portion, a protruding portion and a connecting portion, the weak portion is configured to be at least partially damaged when the battery cell is relieved, the weak portion is annular, the protruding portion is located in the area surrounded by the weak portion, the connecting portion is located outside the weak portion, the protruding portion is a protruding structure protruding in the thickness direction of the pressure relief mechanism, and the minimum thickness of the weak portion is H1, which satisfies 0.01mm≤H1≤0.2mm.

32. The pressure relief mechanism of claim 31, wherein, The area surrounded by the weak portion is a pressure relief area, and the projection area of the pressure relief area in the thickness direction of the pressure relief mechanism is S. 100 mm 2 ≤ S ≤ 450 mm 2 and 0.010 mm ≤ H1 ≤ 0.160 mm; or, 350 mm 2 ≤ S ≤ 850 mm 2 and 0.015 mm ≤ H1 ≤ 0.170 mm; or, 750 mm 2 ≤ S ≤ 1250 mm 2 and 0.020 mm ≤ H1≤ 0.180 mm; or, 1150 mm 2 ≤ S ≤ 1650 mm 2 and 0.025 mm ≤ H1 ≤ 0.190 mm; or, 1550 mm 2 ≤ S ≤ 2100 mm 2 and 0.030 mm ≤ H1 ≤ 0.200 mm.

33. The pressure relief mechanism of claim 32, wherein, 100 mm 2 ≤ S ≤ 450 mm 2 and 0.020 mm ≤ H1 ≤ 0.160 mm; or, 350 mm 2 ≤ S ≤ 850 mm 2 and 0.025 mm ≤ H1 ≤ 0.170 mm; or, 750 mm 2 ≤ S ≤ 1250 mm 2 and 0.030 mm ≤ H1 ≤ 0.180 mm; or, 1150 mm 2 ≤ S ≤ 1650 mm 2 and 0.035 mm ≤ H1 ≤ 0.190 mm; or, 1550 mm 2 ≤ S ≤ 2100 mm 2 and 0.040 mm ≤ H1 ≤ 0.200 mm.

34. The pressure relief mechanism of any of claims 31-33, wherein, The protruding height of the protruding portion is H2, which satisfies 0.2mm≤H2≤4.9mm.

35. The pressure relief mechanism of claim 34, wherein, 0.3mm≤H2≤3mm.

36. A battery, wherein, The battery comprises a plurality of battery cells according to any one of claims 1-30.

37. The battery of claim 36, wherein, The battery comprises a plurality of battery cells, and the plurality of battery cells are arranged in a second direction. The weak portion comprises a first weak section and a second weak section, the first weak section and the second weak section are connected in a head-to-tail manner, a thickness of the first weak section is less than a thickness of the second weak section; In an extension direction of the second weak section, the second weak section comprises a third end and a fourth end, a line connecting the third end and the fourth end is a first line, an included angle between the first line and the second direction is D, and 0≤D≤45° is satisfied.

38. The battery of claim 37, wherein, The first line is parallel to the second direction.

39. The battery of claim 37 or 38, wherein, The second direction is a thickness direction of a wall with a largest outer surface area of the shell.

40. An electrical device, comprising: The battery cell according to any one of claims 1-30 is used to provide electric energy for the electric device.

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