Battery cell, battery, and electrical device

Abstract

The present application relates to the field of batteries, and provides a battery cell, a battery, and an electrical device. The battery cell comprises a housing and a pressure relief component, and the housing is provided with a first wall. The pressure relief component is provided on the first wall, the pressure relief component comprises a first weakened portion, the first weakened portion defines a predetermined pressure relief area, and the pressure relief component is configured to be capable of cracking along at least part of the first weakened portion when relieving pressure from the battery cell. The pressure relief component further comprises a second weakened portion, and the second weakened portion is configured to guide at least part of the predetermined pressure relief area to invert so as to open at least part of the predetermined pressure relief area. The battery cell is provided with the first weakened portion and the second weakened portion, and when pressure is relieved from the battery cell, the first weakened portion cracks, so that a fluid medium in the battery cell flows out to relieve pressure. By means of providing the second weakened portion, the predetermined pressure relief area can be inverted and opened under the guidance of the second weakened portion, which is beneficial for increasing the opening speed of the predetermined pressure relief area to achieve rapid pressure relief, and is beneficial for improving the reliability of the battery cell.

Description

Battery cells, batteries and electrical equipment Technical Field

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

[0002] Batteries are widely used in new energy applications, such as electric vehicles and new energy vehicles. These have become a new trend in the automotive industry. The development of battery technology requires consideration of multiple design factors, including performance parameters such as battery life, energy density, discharge capacity, and charge / discharge rate. Furthermore, battery reliability must be considered. However, current battery reliability is relatively poor.

[0003] Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a battery cell, a battery, and an electrical device, which are intended to improve the problem of poor reliability of batteries in related technologies.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, comprising a shell and a pressure relief component, wherein the shell has a first wall; the pressure relief component is arranged on the first wall, and the pressure relief component includes a first weak portion, which defines a predetermined pressure relief area, and the pressure relief component is configured to be able to split along at least a portion of the first weak portion when the battery cell is pressure-relieved; wherein the pressure relief component also includes a second weak portion, which is configured to guide at least a portion of the predetermined pressure relief area to flip over to open at least a portion of the predetermined pressure relief area.

[0006] In the above technical solution, the battery cell is provided with a first weak portion and a second weak portion. When the battery cell is depressurized, the first weak portion ruptures, allowing the fluid medium in the battery cell to flow out and release the pressure. The provision of the second weak portion weakens the strength of the pressure relief component at the second weak portion, making it easier for the predetermined pressure relief area to flip open under the action of the fluid medium. This not only increases the probability of the predetermined pressure relief area opening, but also increases the speed of the predetermined pressure relief area opening, achieving rapid pressure relief, reducing the risk of battery cell explosion and fire, and promoting the reliability of the battery cell.

[0007] As an optional technical solution of an embodiment of the present application, the shell includes a second wall and a third wall arranged opposite to each other along a first direction, the first wall connects the second wall and the third wall, and along the first direction, the second wall has a first outer surface facing away from the interior of the shell, and the third wall has a second outer surface facing away from the interior of the shell; along the first direction, the second weak portion is arranged between the first weak portion and the first outer surface and / or between the first weak portion and the second outer surface.

[0008] In the above technical solution, when a second weak portion is provided between the first weak portion and the first outer surface, the second weak portion is closer to the first outer surface than the first weak portion, and the stiffness at the location of the first weak portion is less than the stiffness at the location of the second weak portion. When the battery cell releases pressure, the deformation of the pressure relief component at the location of the first weak portion is greater than the deformation of the pressure relief component at the location of the second weak portion, which is conducive to causing the first weak portion to rupture before the second weak portion, allowing the predetermined pressure relief area to flip open under the guidance of the second weak portion. Similarly, when a second weak portion is provided between the first weak portion and the second outer surface, the second weak portion is closer to the second outer surface than the first weak portion, and the stiffness at the location of the first weak portion is less than the stiffness at the location of the second weak portion. When the battery cell releases pressure, the deformation of the pressure relief component at the location of the first weak portion is greater than the deformation of the pressure relief component at the location of the second weak portion, which is conducive to causing the first weak portion to rupture before the second weak portion, allowing the predetermined pressure relief area to flip open under the guidance of the second weak portion.

[0009] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a first groove and a second groove, the pressure relief component forms the first weak portion in the area where the first groove is provided, and the pressure relief component forms the second weak portion in the area where the second groove is provided, the first groove includes at least one groove segment, and the pressure relief component forms a weak section in the area where the groove segment is provided, the cross-sectional area of ​​the weak section perpendicular to its extension direction is the first cross-sectional area, the minimum width of the groove bottom surface of the groove segment is the first width, the minimum thickness of the weak section is the first thickness, and the first cross-sectional area is equal to the product of the first width and the first thickness; the cross-sectional area of ​​the second weak portion perpendicular to its extension direction is the second cross-sectional area, the minimum width of the groove bottom surface of the second groove is the second width, the minimum thickness of the second weak portion is the second thickness, and the second cross-sectional area is equal to the product of the second width and the second thickness.

[0010] In the above technical solution, the first and second weak portions are formed by providing the first and second grooves in the pressure relief component, which is simple, convenient, and low-cost. The first cross-sectional area is equal to the product of the first width and the first thickness, that is, the cross-section of the weak portion perpendicular to its extension direction is rectangular. When measuring the first cross-sectional area, the first width and the first thickness can be measured to calculate the first cross-sectional area. The second cross-sectional area is equal to the product of the second width and the second thickness, that is, the cross-section of the second weak portion perpendicular to its extension direction is rectangular. When measuring the second cross-sectional area, the second width and the second thickness can be measured to calculate the second cross-sectional area.

[0011] As an optional technical solution of an embodiment of the present application, the first width is a1, satisfying: 0.01mm≤a1≤0.8mm, optionally, 0.05mm≤a1≤0.5mm, optionally, 0.1mm≤a1≤0.3mm; and / or the first thickness is h1, satisfying: 0.02mm≤h1≤1mm, optionally, 0.04mm≤h1≤0.6mm, optionally, 0.08mm≤h1≤0.4mm; and / or the second width is a2, satisfying: 0.01mm≤a2≤0.5mm, optionally, 0.04mm≤a2≤0.3mm, optionally, 0.06mm≤a2≤0.15mm; and / or the second thickness is h2, satisfying: 0.1mm≤h2≤2mm, optionally, 0.2mm≤h2≤1.5mm, optionally, 0.5mm≤h2≤1mm.

[0012] In the above technical solution, when a1 ≥ 0.01 mm, the first width is relatively large, which can reduce the risk of the weak section cracking due to changes in air pressure inside the battery cell, thereby improving the reliability of the battery cell. When a1 ≤ 0.8 mm, the first width is not too large, which helps the weak section to crack promptly when the battery cell is depressurized, thereby improving the timeliness of the battery cell's pressure relief. Therefore, when 0.01 mm ≤ a1 ≤ 0.8 mm, the first width is of moderate size, and the weak section is not easily cracked due to changes in air pressure inside the battery cell, but can be cracked promptly when the battery cell is depressurized, thereby improving the timeliness of the battery cell's pressure relief.

[0013] When a1 ≥ 0.05mm, the first width is larger, further reducing the risk of the weak section rupturing due to changes in air pressure within the battery cell, thereby improving the reliability of the battery cell. When a1 ≤ 0.5mm, this facilitates more timely rupture of the weak section during pressure relief, thereby improving the timeliness of pressure relief. Therefore, when 0.05mm ≤ a1 ≤ 0.5mm, a better balance is achieved between battery cell reliability and timeliness of pressure relief.

[0014] When a1 ≥ 0.1mm, the first width is larger, further reducing the risk of the weak section rupturing due to changes in air pressure within the battery cell, thereby improving the reliability of the battery cell. When a1 ≤ 0.3mm, this facilitates more timely rupture of the weak section during pressure relief, thereby improving the timeliness of pressure relief. Therefore, when 0.1mm ≤ a1 ≤ 0.3mm, a better balance is achieved between battery cell reliability and timeliness of pressure relief.

[0015] When h1 ≥ 0.02mm, the first thickness is relatively large, which can reduce the risk of the weak section cracking due to changes in air pressure inside the battery cell, thereby improving the reliability of the battery cell. When h1 ≤ 1mm, the first thickness is not too large, which helps the weak section to crack promptly when the battery cell is depressurized, thereby improving the timeliness of the battery cell's pressure relief. Therefore, when 0.02mm ≤ h1 ≤ 1mm, the first thickness is moderate, making the weak section less likely to crack due to changes in air pressure inside the battery cell, while still allowing it to crack promptly when the battery cell is depressurized, thereby improving the timeliness of the battery cell's pressure relief.

[0016] When h1 ≥ 0.04mm, the first thickness is greater, further reducing the risk of the weak section rupturing due to changes in air pressure within the battery cell, thereby improving the reliability of the battery cell. When h1 ≤ 0.6mm, this facilitates more timely rupture of the weak section during pressure relief, thereby improving the timeliness of pressure relief. Therefore, when 0.04mm ≤ h1 ≤ 0.6mm, a better balance is achieved between battery cell reliability and timely pressure relief.

[0017] When h1 ≥ 0.08mm, the first thickness is greater, further reducing the risk of the weak section rupturing due to pressure fluctuations within the battery cell, thereby improving the reliability of the battery cell. When h1 ≤ 0.4mm, this facilitates more immediate rupture of the weak section during pressure relief, thereby improving the timeliness of pressure relief. Therefore, when 0.08mm ≤ h1 ≤ 0.4mm, a better balance is achieved between battery cell reliability and timely pressure relief.

[0018] When a2 ≥ 0.01mm, the second width is relatively large, which can reduce the risk of the second weak portion cracking due to changes in air pressure inside the battery cell, thereby improving the reliability of the battery cell. When a2 ≤ 0.5mm, the second width is not too large, which helps reduce the resistance to the predetermined pressure relief area from turning, facilitates the predetermined pressure relief area to quickly turn over and open, and improves the timeliness of pressure relief in the battery cell. Therefore, when 0.01mm ≤ a2 ≤ 0.5mm, the second width is moderate, making the second weak portion less likely to crack due to changes in air pressure inside the battery cell, while facilitating the predetermined pressure relief area to quickly turn over and open, thereby improving the timeliness of pressure relief in the battery cell.

[0019] When a2 ≥ 0.04mm, the second width is larger, further reducing the risk of the second weak portion cracking due to changes in air pressure within the battery cell, thereby improving the reliability of the battery cell. When a2 ≤ 0.3mm, the resistance to the predetermined pressure relief area turning is reduced, facilitating its rapid opening and improving the timeliness of pressure relief in the battery cell. Therefore, when 0.04mm ≤ a2 ≤ 0.3mm, a better balance is achieved between battery cell reliability and timely pressure relief.

[0020] When a2 ≥ 0.06mm, the second width is larger, further reducing the risk of the second weak portion cracking due to changes in air pressure within the battery cell, thereby improving the reliability of the battery cell. When a2 ≤ 0.15mm, the resistance to the predetermined pressure relief area turning is reduced, facilitating its rapid opening and improving the timeliness of pressure relief in the battery cell. Therefore, when 0.06mm ≤ a2 ≤ 0.15mm, a better balance is achieved between battery cell reliability and timely pressure relief.

[0021] When h2 ≥ 0.1mm, the second thickness is relatively large, which can reduce the risk of the second weak portion cracking due to changes in air pressure inside the battery cell, thereby improving the reliability of the battery cell. When h2 ≤ 2mm, the second thickness is not too large, which helps reduce the resistance to the predetermined pressure relief area from turning, facilitates the rapid opening of the predetermined pressure relief area, and improves the timeliness of pressure relief in the battery cell. Therefore, when 0.1mm ≤ h2 ≤ 2mm, the second thickness is moderate, making the second weak portion less likely to crack due to changes in air pressure inside the battery cell, while facilitating the rapid opening of the predetermined pressure relief area, thereby improving the timeliness of pressure relief in the battery cell.

[0022] When h2 ≥ 0.2mm, the second thickness is greater, further reducing the risk of the second weak portion cracking due to changes in air pressure within the battery cell, thereby improving the reliability of the battery cell. When h2 ≤ 1.5mm, the resistance to the predetermined pressure relief area turning is reduced, facilitating its rapid opening and improving the timeliness of pressure relief in the battery cell. Therefore, when 0.2mm ≤ h2 ≤ 1.5mm, a better balance is achieved between battery cell reliability and timely pressure relief.

[0023] When h2 ≥ 0.5mm, the second thickness is greater, further reducing the risk of the second weak portion cracking due to pressure fluctuations within the battery cell, thereby improving the reliability of the battery cell. When h2 ≤ 1mm, the resistance to the predetermined pressure relief area is reduced, facilitating its rapid opening and improving the timeliness of pressure relief in the battery cell. Therefore, when 0.5mm ≤ h2 ≤ 1mm, a better balance is achieved between battery cell reliability and timely pressure relief.

[0024] As an optional technical solution of an embodiment of the present application, along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the first weak portion and the first outer surface is a second distance, the minimum distance between the first weak portion and the second outer surface is a third distance, and the ratio of the difference between the second distance and the third distance to the first distance is greater than or equal to 0 and less than or equal to 0.1.

[0025] In the above technical solution, when the ratio of the difference between the second distance and the third distance to the first distance is greater than or equal to 0 and less than or equal to 0.1, the position of the first weak portion is close to the middle position of the first wall along the first direction, and the stiffness of the middle position of the first wall along the first direction is relatively small. When the battery cell is depressurized, the middle position of the first wall along the first direction will undergo a large deformation, which is conducive to causing the first weak portion to crack before the second weak portion, so that the predetermined pressure relief area can be flipped open under the guidance of the second weak portion, which is conducive to improving the reliability of the battery cell.

[0026] As an optional technical solution of an embodiment of the present application, the first wall has a third outer surface facing away from the interior of the shell, and along the thickness direction of the first wall, the projection of the first weak portion covers the center of the third outer surface.

[0027] In the above technical solution, along the thickness direction of the first wall, the projection of the first weak portion covers the center of the third outer surface, and the position of the first weak portion is closer to the middle position of the first wall along the first direction, which is more conducive to the first weak portion to crack before the second weak portion, so that the predetermined pressure relief area can be flipped open under the guidance of the second weak portion, which is beneficial to improving the reliability of the battery cell.

[0028] As an optional technical solution of an embodiment of the present application, along the first direction, a second weak portion is provided between the first weak portion and the first outer surface; along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the second weak portion and the first outer surface is a fourth distance, and the minimum distance between the second weak portion and the second outer surface is a fifth distance. The first weak portion includes at least one weak segment, and the cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area. The cross-sectional area of ​​the second weak portion perpendicular to its extension direction is a second cross-sectional area. When the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or equal to 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1.5.

[0029] In the above technical solution, when the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or equal to 0.4, the second weak portion deviates significantly from the middle position of the first wall along the first direction. At this time, the second weak portion is close to the first outer surface, and the stiffness of the first wall at the second weak portion differs significantly from the stiffness of the first wall at the first weak portion. Therefore, the stiffness has a greater impact on the cracking of the first and second weak portions. If the impact of the stiffness on the first and second weak portions is not considered, the cross-sectional area of ​​the second weak portion perpendicular to its extension direction only needs to be greater than the cross-sectional area of ​​the weak section perpendicular to its extension direction. In other words, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1, so that the first weak portion opens and releases pressure before the second weak portion, and the second weak portion serves as a guide to the predetermined pressure relief zone. However, considering that the rigidity has a greater impact on the cracking of the first and second weak parts (under the same cross-sectional area, the second weak part is more difficult to crack than the first weak part, so the cross-sectional area of ​​the second weak part can be set to be smaller), when the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1, the first weak part can also be opened to release pressure before the second weak part, and the second weak part plays a guiding role in the predetermined pressure relief area. Similarly, because the rigidity has a greater impact on the cracking of the first and second weak parts, when the ratio of the second cross-sectional area to the first cross-sectional area is less than or equal to 1.5, the strength of the pressure relief component at the second weak part position is relatively small, and there is less obstruction to the flipping and opening of the predetermined pressure relief area, making it easier for the predetermined pressure relief area to flip open under the action of the fluid medium.

[0030] As an optional technical solution of an embodiment of the present application, the first wall has a third outer surface facing away from the interior of the shell, the third outer surface is rectangular, and the first direction is parallel to the width direction of the rectangle.

[0031] In the above technical solution, the first weak portion and the second weak portion are arranged along the width direction of the third outer surface. The first weak portion is closer to the middle position of the first wall along the width direction than the second weak portion, and the second weak portion is closer to the edge position of the first wall along the width direction than the first weak portion. The stiffness has a greater impact on the cracking of the first weak portion and the second weak portion.

[0032] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a first groove and a second groove, the pressure relief component forms the first weak portion in the area where the first groove is provided, and the pressure relief component forms the second weak portion in the area where the second groove is provided, the first groove includes at least one groove segment, and the pressure relief component forms a weak section in the area where the groove segment is provided, the cross-sectional area of ​​the weak section perpendicular to its extension direction is the first cross-sectional area, the minimum width of the groove bottom surface of the groove segment is the first width, the minimum thickness of the weak section is the first thickness, and the first cross-sectional area is equal to the product of the first width and the first thickness; the cross-sectional area of ​​the second weak portion perpendicular to its extension direction is the second cross-sectional area, the minimum width of the groove bottom surface of the second groove is the second width, the minimum thickness of the second weak portion is the second thickness, and the second cross-sectional area is equal to the product of the second width and the second thickness; the second thickness is greater than or equal to the first thickness, and the second width is less than or equal to the first width.

[0033] In the above technical solution, by making the second thickness greater than or equal to the first thickness and the second width less than or equal to the first width, not only can the second weak portion better guide the predetermined pressure relief area to open, but also the second width can be made as small as possible under the condition that when the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1.5, thereby reducing the area occupied by the second groove on the third outer surface of the pressure relief component.

[0034] As an optional technical solution of an embodiment of the present application, along the first direction, a second weak portion is provided between the first weak portion and the first outer surface; along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the second weak portion and the first outer surface is a fourth distance, and the minimum distance between the second weak portion and the second outer surface is a fifth distance. The first weak portion includes at least one weak segment, and the cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area. The cross-sectional area of ​​the second weak portion perpendicular to its extension direction is a second cross-sectional area. When the ratio of the difference between the fifth distance and the fourth distance to the first distance is less than 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1.5 and less than or equal to 5.

[0035] In the above technical solution, when the ratio of the difference between the fifth distance and the fourth distance to the first distance is less than 0.4, the second weak portion deviates from the middle position of the first wall along the first direction by a smaller distance. At this time, the second weak portion is also relatively close to the middle position of the first wall along the first direction. The stiffness of the first wall at the second weak portion is slightly different from the stiffness of the first wall at the first weak portion, and the stiffness has a smaller impact on the rupture of the first and second weak portions. When the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1.5, the first weak portion can open and relieve pressure before the second weak portion. The second weak portion serves to guide the predetermined pressure relief zone, reducing the risk of the second weak portion rupturing before the first weak portion. When the ratio of the second cross-sectional area to the first cross-sectional area is less than or equal to 5, the strength of the pressure relief component at the second weak portion is relatively low, which lessens the obstruction to the flipping and opening of the predetermined pressure relief zone, making the predetermined pressure relief zone more easily flipped and opened under the action of the fluid medium.

[0036] As an optional technical solution of an embodiment of the present application, the first wall has a third outer surface facing away from the interior of the shell, the third outer surface is rectangular, and the first direction is parallel to the length direction of the rectangle.

[0037] In the above technical solution, the first weak portion and the second weak portion are arranged along the length direction of the third outer surface. The first weak portion and the second weak portion are both closer to the middle position of the first wall along the length direction, and the stiffness has less influence on the cracking of the first weak portion and the second weak portion.

[0038] As an optional technical solution of an embodiment of the present application, the ratio of the second cross-sectional area to the first cross-sectional area is greater than or equal to 2.13 and less than or equal to 4.67.

[0039] In the above technical solution, when the ratio of the second cross-sectional area to the first cross-sectional area is greater than or equal to 2.13, the first weakened portion is more likely to open and release pressure before the second weakened portion. The second weakened portion acts as a guide to the predetermined pressure relief zone, further reducing the risk of the second weakened portion rupturing before the first weakened portion. When the ratio of the second cross-sectional area to the first cross-sectional area is less than or equal to 4.67, the strength of the pressure relief component at the second weakened portion is reduced, thereby minimizing the obstruction to the opening of the predetermined pressure relief zone, making it easier for the predetermined pressure relief zone to open under the influence of the fluid medium.

[0040] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a first groove and a second groove, the pressure relief component forms the first weak portion in the area where the first groove is provided, and the pressure relief component forms the second weak portion in the area where the second groove is provided, the first groove includes at least one groove segment, and the pressure relief component forms a weak section in the area where the groove segment is provided, the cross-sectional area of ​​the weak section perpendicular to its extension direction is the first cross-sectional area, the minimum width of the groove bottom surface of the groove segment is the first width, the minimum thickness of the weak section is the first thickness, and the first cross-sectional area is equal to the product of the first width and the first thickness; the cross-sectional area of ​​the second weak portion perpendicular to its extension direction is the second cross-sectional area, the minimum width of the groove bottom surface of the second groove is the second width, the minimum thickness of the second weak portion is the second thickness, and the second cross-sectional area is equal to the product of the second width and the second thickness; the second thickness is greater than or equal to the first thickness, and the second width is greater than or equal to the first width.

[0041] In the above technical solution, by making the second thickness greater than or equal to the first thickness and the second width greater than or equal to the first width, the influence of the stiffness change in different areas of the first wall on the cracking of the weak section and the second weak portion can be further reduced, so that the weak section cracks when the battery cell is depressurized, and the second weak portion guides the flipping of the predetermined pressure relief area.

[0042] As an optional technical solution of the embodiment of the present application, the first cross-sectional area is S1, which satisfies: 0.0002mm 2 ≤S1≤0.8mm 2 , optionally, 0.002mm 2 ≤S1≤0.3mm 2 , optionally, 0.008mm 2 ≤S1≤0.12mm 2 .

[0043] In the above technical solution, when S1≥0.0002mm 2 When S1≤0.8mm, the cross-sectional area of ​​the first weak section perpendicular to its extension direction is larger, and it is not easy to crack when subjected to external impact, which is beneficial to improving the reliability of the battery cell. 2 When the cross-sectional area of ​​the first weak section perpendicular to its extension direction is not too large, when the internal pressure of the battery cell reaches the detonation pressure, the first weak section is easy to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.8mm 2 It can both resist external impact and easily open and release pressure when the internal pressure of the battery cell reaches the detonation pressure.

[0044] When S1≥0.002mm2 When S1≤0.3mm, the risk of the first weak section cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell. 2 When the internal pressure of the battery cell reaches the detonation pressure, the first weak section is more likely to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.3mm 2 When the battery is in a closed state, it can better resist external impact and is easy to open and release pressure when the internal pressure of the battery cell reaches the detonation pressure.

[0045] When S1≥0.008mm 2 When S1≤0.12mm, the risk of the first weak section cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell. 2 When the internal pressure of the battery cell reaches the detonation pressure, the first weak section is more likely to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.12mm 2 When the battery is in a closed state, it can better resist external impact and is easy to open and release pressure when the internal pressure of the battery cell reaches the detonation pressure.

[0046] As an optional technical solution of the embodiment of the present application, the second cross-sectional area is S2, which satisfies: 0.001mm 2 ≤S2≤1mm 2 , optionally, 0.008mm 2 ≤S2≤0.45mm 2 ; Optionally, 0.03mm 2 ≤S2≤0.15mm 2 .

[0047] In the above technical solution, when S2≥0.001mm 2 When S2≤1mm, the cross-sectional area of ​​the second weak part perpendicular to its extension direction is larger, and it is not easy to crack when subjected to external impact, which is beneficial to improving the reliability of the battery cell. 2 When the cross-sectional area of ​​the second weak portion perpendicular to its extension direction is not too large, it is beneficial to reduce the resistance of the predetermined pressure relief area to flip over, and facilitate the predetermined pressure relief area to flip open quickly. 2 ≤S2≤1mm 2 , which can both resist external impact and facilitate rapid flipping and opening of the predetermined pressure relief area.

[0048] When S2≥0.008mm 2 When S2≤0.45mm, the risk of the second weak part cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell.2 , the resistance to the predetermined pressure relief area turning over is smaller, which facilitates the predetermined pressure relief area to turn over and open quickly. Therefore, when 0.008mm 2 ≤S2≤0.45mm 2 When opening, it can better resist external impact and facilitate the rapid flipping and opening of the predetermined pressure relief area.

[0049] When S2≥0.03mm 2 When S2≤0.15mm, the risk of the second weak part cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell. 2 , the resistance to the predetermined pressure relief area turning over is smaller, which facilitates the predetermined pressure relief area to turn over and open quickly. Therefore, when 0.03mm 2 ≤S2≤0.15mm 2 When opening, it can better resist external impact and facilitate the rapid flipping and opening of the predetermined pressure relief area.

[0050] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided. The second groove is provided on the surface of the pressure relief component facing the interior of the shell.

[0051] In the above technical solution, the second weak portion is formed by providing a second groove in the pressure relief component, which is simple, convenient, and low-cost. Furthermore, by providing the second groove on the surface of the pressure relief component facing the interior of the housing, the tension that the predetermined pressure relief area needs to overcome during flipping is reduced, thereby facilitating rapid flipping and opening of the predetermined pressure relief area, thereby improving the reliability of the battery cell.

[0052] As an optional technical solution of an embodiment of the present application, the pressure relief component has a first surface and a second surface arranged opposite to each other in the thickness direction of the first wall, the first surface is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, and the second surface is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided.

[0053] In the above technical solution, the first and second weakened portions are formed by providing the first and second grooves in the pressure relief component, which is simple, convenient, and low-cost. By providing the first and second grooves on the first and second surfaces of the pressure relief component, respectively, the first and second grooves are located on opposite sides of the pressure relief component, thereby facilitating machining of the first and second grooves on opposite sides of the pressure relief component, and thereby reducing mutual influence between the first and second grooves during machining.

[0054] As an optional technical solution of an embodiment of the present application, the first surface is the surface of the pressure relief component facing away from the interior of the shell, and the second surface is the surface of the pressure relief component facing the interior of the shell.

[0055] In the above technical solution, by providing the first groove on the surface of the pressure relief component facing away from the interior of the housing, the tension that the first weak portion needs to overcome when rupturing is reduced, making it easier to rupture. By providing the second groove on the surface of the pressure relief component facing the interior of the housing, the tension that the predetermined pressure relief area needs to overcome when flipping is reduced, thereby facilitating rapid flipping and opening of the predetermined pressure relief area, which is beneficial for improving the reliability of the battery cell.

[0056] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided. The first groove includes a first groove section and a second groove section, and the first groove section and the second groove section are connected. The pressure relief component forms a weak section in the area where the first groove section and the second groove section are provided, respectively, and the two weak sections jointly define the predetermined pressure relief area.

[0057] In the above technical solution, the first groove section and the second groove section are interconnected structures, so that the first groove section and the second groove section jointly define a predetermined pressure relief area. On the one hand, this can increase the pressure relief area of ​​the battery cell to increase the pressure relief rate of the battery cell. On the other hand, it makes the position where the first groove section and the second groove section are connected to each other weaker, which is easier to crack and open the predetermined pressure relief area to release the internal pressure of the battery cell.

[0058] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, the first groove includes a first groove section, a second groove section and a third groove section, the first groove section and the third groove section are arranged opposite to each other, the second groove section connects the first groove section and the third groove section, and the pressure relief component forms a weak section in the area where the first groove section, the second groove section and the third groove section are provided, respectively, and the three weak sections jointly define the predetermined pressure relief area.

[0059] In the above technical solution, the first groove includes a first groove section, a second groove section and a third groove section, and the second groove section connects the first groove section and the third groove section, so that the pressure relief component can split along the first groove section, the second groove section and the third groove section when the battery cell releases pressure, so as to open the predetermined pressure relief area to release the internal pressure of the battery cell. The first groove with this structure makes the connection position between the first groove section and the second groove section and the connection position between the first groove section and the third groove section weaker, easier to split and open the predetermined pressure relief area for pressure relief, and can further improve the pressure relief area and pressure relief rate of the battery cell.

[0060] As an optional technical solution of an embodiment of the present application, the first weak portion defines two predetermined pressure relief areas, and the two predetermined pressure relief areas are respectively located on both sides of the second groove section, and each predetermined pressure relief area corresponds to at least one second weak portion.

[0061] In the above technical solution, the first weak portion defines two predetermined pressure relief areas, and each predetermined pressure relief area is correspondingly provided with at least one second weak portion. When the battery cell is depressurized, the two predetermined pressure relief areas are flipped open under the guidance of their corresponding second weak portions, so that the battery cell has a larger pressure relief area, which is beneficial to improving the pressure relief rate of the battery cell and improving the reliability of the battery cell.

[0062] As an optional technical solution of an embodiment of the present application, a second weak portion is correspondingly provided in each predetermined pressure relief area, the pressure relief component is provided with a second groove, the pressure relief component forms the second weak portion in the area where the second groove is provided, and the first groove is located between the two second grooves.

[0063] In the above technical solution, the predetermined pressure relief areas correspond one-to-one with the second weak portions, which can reduce the number of second weak portions provided, reduce the number of times the pressure relief component needs to be processed, and reduce the stress on the pressure relief component. The first groove is arranged between the two second grooves. When the battery cell releases pressure, the pressure relief component can split along the first groove section, the second groove section, and the third groove section, thereby opening the two predetermined pressure relief areas. The two predetermined pressure relief areas are then flipped open under the guidance of their corresponding second weak portions, giving the battery cell a larger pressure relief area, which is beneficial for improving the pressure relief rate of the battery cell and enhancing the reliability of the battery cell.

[0064] As an optional technical solution of an embodiment of the present application, the position where the second slot segment is connected to the first slot segment deviates from the two ends of the first slot segment, and the position where the second slot segment is connected to the third slot segment deviates from the two ends of the third slot segment.

[0065] In the above technical solution, by setting the connection position between the second groove segment and the first groove segment to be located between the two ends of the second groove segment, and setting the connection position between the second groove segment and the third groove segment to be located between the two ends of the third groove segment, so that the first groove segment, the second groove segment and the third groove segment form a structure similar to an "H" shape, so that predetermined pressure relief areas can be formed on both sides of the second groove segment of the first groove, and the two predetermined pressure relief areas can be opened in a split manner to relieve pressure when the battery cell is depressurized, which is beneficial to further increase the pressure relief effect of the battery cell and can effectively improve the pressure relief rate of the battery cell.

[0066] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided, and the first groove section, the second groove section and the third groove section are all spaced apart from the second groove.

[0067] In the above technical solution, by arranging the first groove section, the second groove section and the third groove section to be spaced apart from the second groove, on the one hand, the mutual influence between the first groove and the second groove during the processing can be reduced; on the other hand, the phenomenon that the pressure relief component cracks along the second groove when the pressure relief component cracks along the first groove to relieve pressure can be reduced, and the stress influence between the area where the first groove of the pressure relief component is set and the area where the second groove of the pressure relief component is set can be reduced.

[0068] As an optional technical solution of an embodiment of the present application, the second slot segment and the second groove are arranged opposite to each other along a first direction, and along the first direction, the first slot segment and the third slot segment are both arranged spaced apart from the second groove.

[0069] In the above technical solution, by arranging the second slot segment and the second groove relative to each other along the first direction, the first slot segment and the third slot segment are both spaced apart from the second groove in the first direction, so that the predetermined pressure relief area defined by the first slot segment, the second slot segment and the third slot segment can be flipped around the area of ​​the pressure relief component where the second groove is provided when the pressure relief component is opened, and the flipping angle of the predetermined pressure relief area after being opened can be increased, thereby increasing the pressure relief area of ​​the battery cell.

[0070] As an optional technical solution of an embodiment of the present application, the first wall has a third outer surface facing away from the interior of the shell, the third outer surface is rectangular, and the first direction is parallel to the length direction or width direction of the rectangle.

[0071] In the above technical solution, the second groove segment and the second groove are arranged along the length or width of the third outer surface. Along the length or width of the third outer surface, the first and third groove segments are spaced apart from the second groove. The large space along the length or width of the third outer surface facilitates the processing of the first and second grooves. Furthermore, during production, the detonation pressure of multiple processed battery cells is relatively consistent.

[0072] As an optional technical solution of an embodiment of the present application, the pressure relief component has a first surface and a second surface arranged opposite to each other in the thickness direction of the first wall, and the pressure relief component is provided with a first groove, and the first groove includes a multi-level groove arranged in sequence along the direction from the first surface to the second surface. In the two adjacent levels of the grooves, the first-level groove away from the first surface is arranged at the groove bottom surface of the first-level groove close to the first surface; wherein the groove bottom wall of the first-level groove farthest from the first surface among the multi-level grooves is the first weak portion.

[0073] In the above technical solution, the multi-level grooves are sequentially arranged on the pressure relief component along the direction from the first surface to the second surface. During molding, the multi-level grooves can be formed step by step, thereby reducing the molding force on the pressure relief component and reducing the risk of cracks in the pressure relief component. The pressure relief component is not likely to fail due to cracks in the position where the grooves are set, thereby improving the reliability of the battery cell. When forming the multi-level grooves, stamping or cold heading can be used, so that the groove wall will undergo cold work hardening (the grain arrangement changes, resulting in lattice distortion, reducing the plasticity of the metal and increasing the hardness of the material), and its ability to resist external impact is enhanced, and it is not easily damaged by external impact. This is conducive to reducing the risk of leakage in the pressure relief component.

[0074] As an optional technical solution of the embodiment of the present application, the pressure relief component is integrally formed with the first wall.

[0075] In the above technical solution, the pressure relief component is integrally formed with the first wall, eliminating the need for additional welding or bonding processes, which helps reduce the risk of leakage from the pressure relief component. Furthermore, during production, it is easier to ensure that the detonation pressures of multiple battery cells produced are relatively consistent.

[0076] As an optional technical solution of an embodiment of the present application, the pressure relief component is separately provided from the first wall, the first wall is provided with a pressure relief hole, and the pressure relief component is installed on the first wall and covers the pressure relief hole.

[0077] In the above technical solution, the pressure relief component is provided separately from the first wall and installed on the first wall, so as to facilitate processing and manufacturing.

[0078] As an optional technical solution of the embodiment of the present application, the battery cell includes an electrode assembly, the electrode assembly is accommodated in the housing, and the first wall supports the electrode assembly along the direction of gravity.

[0079] In the above technical solution, the first wall supports the electrode assembly along the direction of gravity, and the pressure relief component is arranged on the first wall. In this way, when the battery cell is depressurized, the ejected fluid medium is not easy to act on other electrical connection components, thereby reducing the risk of short circuit when the battery cell is depressurized.

[0080] As an optional technical solution of the embodiment of the present application, the battery cell includes an electrode terminal, and the electrode terminal is provided on other walls of the housing except the first wall.

[0081] In the above technical solution, the electrode terminals and the pressure relief component are respectively arranged on different walls of the shell. When the battery cell is depressurized, the ejected fluid medium is not likely to act on the electrode terminals and cause the electrode terminals to short-circuit, thereby reducing the risk of short circuit when the battery cell is depressurized.

[0082] As an optional technical solution of the embodiment of the present application, the electrode terminal is arranged on the wall of the shell opposite to the first wall.

[0083] In the above technical solution, the electrode terminal is arranged on the wall of the shell opposite to the first wall, and the electrode terminal is far away from the pressure relief component. When the battery cell is depressurized, the ejected fluid medium is less likely to act on the electrode terminal and cause the electrode terminal to short-circuit, further reducing the risk of short circuit when the battery cell is depressurized.

[0084] As an optional technical solution of an embodiment of the present application, the outer shell includes a shell and an end cover, the shell has an opening; the end cover is connected to the shell and closes the opening; wherein, the end cover is the first wall, or the shell includes the first wall.

[0085] In the above technical solution, when the end cap is the first wall, the pressure relief component is disposed on the end cap, which simplifies and facilitates manufacturing. When the housing includes the first wall, the pressure relief component is disposed on one wall of the housing. The fluid medium ejected by the pressure relief component is less likely to act on other electrical connection structures on the end cap, thereby reducing the risk of short circuits in the battery cells.

[0086] In a second aspect, an embodiment of the present application further provides a battery, which includes the above-mentioned battery cell.

[0087] In a third aspect, an embodiment of the present application further provides an electrical device, which includes the above-mentioned battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0089] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0090] FIG2 is an exploded view of the structure of a battery provided in some embodiments of the present application;

[0091] FIG3 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0092] FIG4 is an exploded view of the structure of a battery cell provided in some embodiments of the present application;

[0093] FIG5 is a bottom view of a housing of a battery cell provided in some embodiments of the present application;

[0094] FIG6 is a partial cross-sectional view of a housing of a battery cell provided in some embodiments of the present application;

[0095] FIG7 is a partial enlarged view of the portion A of the housing shown in FIG6 ;

[0096] FIG8 is a bottom view of a housing of a battery cell provided in some other embodiments of the present application;

[0097] FIG9 is a bottom view of a housing of a battery cell provided in some further embodiments of the present application;

[0098] FIG10 is a bottom view of a housing of a battery cell provided in some other embodiments of the present application;

[0099] FIG11 is a bottom view of the outer shell of a battery cell provided in some other embodiments of the present application.

[0100] Icon: 1000-vehicle; 100-battery; 10-box; 11-first box body; 12-second box body; 20-battery cell; 21-housing; 211-first wall; 2111-first surface; 2112-second surface; 2113-third outer surface; 212-second wall; 2121-first outer surface; 213-third wall; 2131-second outer surface; 214-pressure relief component; 2141-first level groove; 2142-second level groove; 2 143-third-stage groove; 21431-predetermined pressure relief area; 2143a-first groove section; 2143b-second groove section; 2143c-third groove section; 2144-first weak portion; 2145-second weak portion; 21451-second groove; 2146-first groove; 215-shell; 2151-opening; 216-end cover; 22-electrode assembly; 221-electrode ear; 23-electrode terminal; 24-current collecting component; 200-controller; 300-motor. DETAILED DESCRIPTION

[0101] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0102] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0103] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0104] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0105] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0106] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0107] The term "plurality" used in this application refers to two or more (including two).

[0108] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0109] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0110] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0111] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0112] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0113] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0114] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.

[0115] In some embodiments, a positive electrode may utilize a metal foam. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or the like. When a metal foam is used as the positive electrode, the surface of the metal foam may or may not include a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled or / and deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0116] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0117] As an example, the negative electrode current collector may be a metal foil, a metal foam, or a composite current collector. For example, as the metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. may be used. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, etc. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0118] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0119] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0120] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0121] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0122] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0123] In some embodiments, the separator is a separator membrane. There are many types of separator membranes, and any known separator membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0124] As an example, the separator can be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. In the case of a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0125] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0126] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel, or solid. Liquid electrolytes include an electrolyte salt and a solvent.

[0127] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0128] In some embodiments, solvent can comprise at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl 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, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.Solvent also can be selected ether solvent.Ether solvent can comprise one or more in ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0129] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0130] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0131] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, or the like.

[0132] As an example, the inorganic solid electrolyte may include an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0133] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0134] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0135] In some embodiments, the electrode assembly is a laminate structure.

[0136] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0137] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0138] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0139] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0140] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0141] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0142] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0143] In some embodiments, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0144] As an example, the battery cells may be cylindrical, prismatic, soft-pack or other shaped battery cells. Prismatic battery cells include but are not limited to square-shell, blade-shaped, and polygonal batteries, such as hexagonal batteries.

[0145] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0146] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0147] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0148] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0149] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0150] Batteries are widely used in new energy applications, such as electric vehicles and new energy vehicles. These have become a new trend in the automotive industry. The development of battery technology requires consideration of multiple design factors, including performance parameters such as battery life, energy density, discharge capacity, and charge / discharge rate. Furthermore, battery reliability must be considered. However, current battery reliability is relatively poor.

[0151] For battery cells, in order to improve the reliability of battery cells, the existing technology is to weld a pressure relief mechanism on the battery cells. A weak portion is provided on the pressure relief mechanism, and the weak portion defines a pressure relief portion. When the internal pressure of the battery cell reaches the detonation pressure, the weak portion cracks and the pressure relief portion opens to release the pressure inside the battery cell, thereby reducing the risk of battery cell explosion or fire.

[0152] However, when the battery cell is depressurized, often only a part of the weak part is cracked. In this way, the pressure relief part may not be able to open, or the pressure relief part can only open a smaller opening, or although the pressure relief part can be fully opened, the opening speed is slow, resulting in a slow pressure relief speed and the inability to quickly release the pressure inside the battery cell. As a result, the battery cell still has a greater risk of explosion and fire, resulting in poor reliability of the battery cell.

[0153] In view of this, an embodiment of the present application provides a battery cell, comprising a housing and a pressure relief component, wherein the housing has a first wall, and the pressure relief component is disposed on the first wall. The pressure relief component includes a first weakened portion, which defines a predetermined pressure relief zone, and is configured to rupture along at least a portion of the first weakened portion when the battery cell releases pressure. The pressure relief component also includes a second weakened portion, which is configured to guide at least a portion of the predetermined pressure relief zone to flip, thereby opening at least a portion of the predetermined pressure relief zone.

[0154] The battery cell is provided with a first weak portion and a second weak portion. When the battery cell is depressurized, the first weak portion ruptures, allowing the fluid medium inside the battery cell to flow out and release the pressure. The provision of the second weak portion weakens the strength of the pressure relief component at the second weak portion, making it easier for the predetermined pressure relief area to flip open under the action of the fluid medium. This not only increases the probability of the predetermined pressure relief area opening, but also increases the speed of opening of the predetermined pressure relief area, achieving rapid pressure relief, reducing the risk of battery cell explosion and fire, and promoting the reliability of the battery cell.

[0155] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and batteries disclosed in this application can be used to form the electrical device, thereby improving the reliability of the battery cells.

[0156] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0157] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device according to an embodiment of the present application.

[0158] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000. The battery 100 can be arranged at the bottom of the vehicle 1000, or at the head of the vehicle 1000, or at the tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can be used as an operating power source or a power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0159] In some embodiments of the present application, the battery 100 can not only serve as the operating power source or usage power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0160] 2 and 3 , FIG2 is an exploded view of a battery 100 according to some embodiments of the present invention, and FIG3 is a schematic diagram of a battery cell 20 according to some embodiments of the present invention. The battery 100 includes a housing 10 and a battery cell 20 , wherein the battery cell 20 is accommodated in the housing 10 .

[0161] The housing 10 is used to provide assembly space for the battery cells 20 and can adopt a variety of structures. In some embodiments, the housing 10 can include a first housing body 11 and a second housing body 12. The first housing body 11 and the second housing body 12 cover each other, and the first housing body 11 and the second housing body 12 jointly define an assembly space for accommodating the battery cells 20. The second housing body 12 can be a hollow structure with one end open, and the first housing body 11 can be a plate-like structure. The first housing body 11 covers the open side of the second housing body 12, so that the first housing body 11 and the second housing body 12 jointly define the assembly space. The first housing body 11 and the second housing body 12 can also be hollow structures with one end open, and the open side of the first housing body 11 covers the open side of the second housing body 12.

[0162] Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder, a cuboid or a cube, etc. For example, in FIG2 , the box body 10 is in the shape of a cuboid.

[0163] In the battery 100, there can be one or more battery cells 20 disposed within the housing 10. When there are multiple battery cells 20 disposed within the housing 10, the multiple battery cells 20 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel configurations within the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery 100 can be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid configuration to form a battery module, which is then further connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed within the housing 10.

[0164] In some embodiments, the battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, which is used to connect the multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20 .

[0165] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be a rectangular parallelepiped, a cylinder, a prism, or other shapes. For example, in FIG3 , the battery cell 20 is a rectangular parallelepiped.

[0166] According to some embodiments of the present application, please refer to Figures 3, 4, 5, 6 and 7. Figure 4 is an exploded view of the structure of the battery cell 20 provided in some embodiments of the present application. Figure 5 is a bottom view of the outer shell 21 of the battery cell 20 provided in some embodiments of the present application. Figure 6 is a partial cross-sectional view of the outer shell 21 of the battery cell 20 provided in some embodiments of the present application. Figure 7 is a partial enlarged view of point A of the outer shell 21 shown in Figure 6. An embodiment of the present application provides a battery cell 20, the battery cell 20 includes a outer shell 21 and a pressure relief component 214, the outer shell 21 has a first wall 211, and the pressure relief component 214 is arranged on the first wall 211. The pressure relief component 214 includes a first weak portion 2144, the first weak portion 2144 defines a predetermined pressure relief area 21431, and the pressure relief component 214 is configured to be able to split along at least a portion of the first weak portion 2144 when the battery cell 20 is depressurized. The pressure relief component 214 further includes a second weak portion 2145 , which is configured to guide at least a portion of the predetermined pressure relief area 21431 to flip over, so as to open at least a portion of the predetermined pressure relief area 21431 .

[0167] The battery cell 20 refers to the smallest unit constituting the battery 100 .

[0168] The housing 21 includes an end cover 216 and a shell 215 . The shell 215 has an opening 2151 . The end cover 216 is connected to the shell 215 and closes the opening 2151 .

[0169] The end cap 216 refers to a component that covers the opening 2151 of the shell 215 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 216 can be adapted to the shape of the shell 215 to match the shell 215. Optionally, the end cap 216 can be made of a material with a certain hardness and strength (such as an aluminum alloy), so that the end cap 216 is not easily deformed when squeezed or collided, so that the battery cell 20 can have a higher structural strength and improved safety performance. The material of the end cap 216 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application are not particularly limited to this. In some embodiments, the battery cell 20 also includes an insulating member, which is arranged on the inner side of the end cap 216. The insulating member can be used to isolate the electrical connection components in the shell 215 from the end cap 216 to reduce the risk of short circuit. Exemplary, the insulating member can be plastic, rubber, etc.

[0170] The housing 215 is a component used to cooperate with the end cap 216 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 22, electrolyte, and other components. The housing 215 and the end cap 216 can be independent components. An opening 2151 can be provided on the housing 215, and the end cap 216 is closed at the opening 2151 to form the internal environment of the battery cell 20. Without limitation, the end cap 216 and the housing 215 can also be integrated. Specifically, the end cap 216 and the housing 215 can form a common joint surface before other components are inserted into the housing. When the interior of the housing 215 needs to be encapsulated, the end cap 216 is closed to the housing 215. The housing 215 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 215 can be determined according to the specific shape and size of the electrode assembly 22. The shell 215 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0171] The electrode assembly 22 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 22 may be contained in the housing 21. The electrode assembly 22 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active materials constitute the main body of the electrode assembly 22, and the parts of the positive electrode sheet and the negative electrode sheet without active materials each constitute a tab 221. The positive electrode tab and the negative electrode tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery 100, the positive electrode active material and the negative electrode active material react with the electrolyte.

[0172] The first wall 211 may be the end cap 216 of the housing 21, or may be a wall of the shell 215 of the housing 21. For example, in Figures 3 and 4, the first wall 211 is the bottom wall of the shell 215 that is disposed opposite the end cap 216. In other embodiments, the first wall 211 may also be a side wall of the shell 215 that is adjacent to and connected to the end cap 216.

[0173] The pressure relief component 214 can be a component mounted on the first wall 211. In this case, the pressure relief component 214 is separately mounted and connected to the first wall 211. For example, the pressure relief component 214 is a bursting disk mounted on the first wall 211. The pressure relief component 214 can also be a portion of the first wall 211. In this case, the pressure relief component 214 and the first wall 211 are integrally formed. The location of the pressure relief component 214 can be used to determine which wall of the housing 21 is the first wall 211. For example, when the pressure relief component 214 is mounted on the end cap 216, the end cap 216 is the first wall 211. When the pressure relief component 214 is mounted on the bottom wall of the housing 215, the bottom wall is the first wall 211. When the pressure relief component 214 is mounted on a side wall of the housing 215, the side wall is the first wall 211.

[0174] The first weak portion 2144 serves as a pressure relief mechanism, allowing the pressure relief component 214 to rupture along the first weak portion 2144 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, thereby releasing the pressure within the battery cell 20. In some embodiments, the strength of the pressure relief component 214 at the first weak portion 2144 can be lower than the strength at other locations of the pressure relief component 214. This allows the first weak portion 2144 to rupture under the influence of the internal pressure to release the pressure within the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value. In other embodiments, the melting point of the pressure relief component 214 at the first weak portion 2144 can be lower than the melting point of the other locations of the pressure relief component 214. This allows the first weak portion 2144 to rupture under the influence of high temperature when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, thereby releasing the pressure within the battery cell 20.

[0175] The first weak portion 2144 defines a predetermined pressure relief area 21431 . When the battery cell 20 releases pressure, the first weak portion 2144 cracks along the edge of the predetermined pressure relief area 21431 , allowing the predetermined pressure relief area 21431 to open and release pressure.

[0176] The second weak portion 2145 guides at least a portion of the predetermined pressure relief area 21431 to flip open. Optionally, the second weak portion 2145 has greater strength than the first weak portion 2144. When the battery cell 20 releases pressure, the first weak portion 2144 first ruptures, allowing the fluid medium within the battery cell 20 to escape and release pressure. Subsequently, under the influence of the fluid medium, the predetermined pressure relief area 21431 can flip outward about the second weak portion 2145, creating a larger opening 2151 and achieving rapid pressure relief.

[0177] The battery cell 20 is provided with a first weak portion 2144 and a second weak portion 2145. When the battery cell 20 releases pressure, the first weak portion 2144 ruptures, allowing the fluid medium within the battery cell 20 to flow out and release pressure. The provision of the second weak portion 2145 weakens the strength of the pressure relief component 214 at the location of the second weak portion 2145, making it easier for the predetermined pressure relief area 21431 to flip open under the action of the fluid medium. This not only increases the probability of the predetermined pressure relief area 21431 opening, but also increases the speed of opening of the predetermined pressure relief area 21431, achieving rapid pressure relief, reducing the risk of explosion or fire in the battery cell 20, and thus improving the reliability of the battery cell 20.

[0178] In some embodiments, as shown in FIG. 4 , the battery cell 20 may further include an electrode terminal 23 . The electrode terminal 23 is insulated and mounted on the housing 21 . The electrode terminal 23 is electrically connected to the electrode assembly 22 to output or input electrical energy of the battery cell 20 .

[0179] It should be noted that the electrode terminal 23 is insulated and mounted on the housing 21 , that is, there is no electrical connection between the electrode terminal 23 and the housing 21 .

[0180] 3 and 4 , the battery cell 20 includes two electrode terminals 23 , which are spaced apart on the end cover 216 . Correspondingly, each electrode assembly 22 has two pole tabs 221 , and the polarities of the two pole tabs 221 are opposite. The two electrode terminals 23 are electrically connected to the two pole tabs 221 of the electrode assembly 22 , respectively, to realize the input or output of the positive and negative poles of the battery cell 20 .

[0181] Exemplarily, the electrode terminal 23 may be made of a variety of materials. For example, the electrode terminal 23 may be made of copper, iron, aluminum, steel, or aluminum alloy.

[0182] Optionally, the electrode terminals 23 may be mounted on the housing 21 in various configurations. For example, in Figures 3 and 4 , both electrode terminals 23 are mounted on the end cap 216 of the housing 21. Of course, the structure of the battery cell 20 is not limited thereto. In other embodiments, both electrode terminals 23 may be mounted on the shell 215 of the housing 21. Similarly, one electrode terminal 23 may be mounted on the shell 215 of the housing 21, while the other electrode terminal 23 may be mounted on the end cap 216 of the housing 21.

[0183] In some embodiments, as shown in Figure 4, the battery cell 20 may also include two current collecting components 24, both of which are arranged in the outer shell 21, and each current collecting component 24 is used to connect an electrode terminal 23 and a plurality of electrode assemblies 22 with the same polarity of the electrode lugs 221 to achieve electrical connection between the electrode terminal 23 and the electrode assembly 22, which is conducive to reducing the difficulty of assembly between the electrode lug 221 and the electrode terminal 23.

[0184] For example, the current collecting member 24 may be made of a variety of materials. For example, the current collecting member 24 may be made of copper, iron, aluminum, steel, or aluminum alloy.

[0185] In some embodiments, referring to Figures 3, 4, 5, 6, and 7, the housing 21 includes a second wall 212 and a third wall 213 disposed opposite each other along a first direction, with a first wall 211 connecting the second wall 212 and the third wall 213. Along the first direction, the second wall 212 has a first outer surface 2121 facing away from the interior of the housing 21, and the third wall 213 has a second outer surface 2131 facing away from the interior of the housing 21. Along the first direction, a second weak portion 2145 is disposed between the first weak portion 2144 and the first outer surface 2121 and / or between the first weak portion 2144 and the second outer surface 2131.

[0186] Please refer to FIG. 5 , FIG. 6 and FIG. 7 , the first direction is the X direction shown in the figures.

[0187] Along the first direction, the second wall 212 and the third wall 213 are disposed opposite each other. The first wall 211 connects the second wall 212 and the third wall 213. The first wall 211 and the second wall 212 are respectively two adjacent and interconnected walls of the housing 21, and the first wall 211 and the third wall 213 are respectively two adjacent and interconnected walls of the housing 21, and the second wall 212 and the third wall 213 are respectively two oppositely disposed walls of the housing 21.

[0188] For example, when the first wall 211 is the bottom wall of the housing 215, the second wall 212 and the third wall 213 are two opposite side walls of the housing 215. When the first wall 211 is the side wall of the housing 215, the second wall 212 can be the end cap 216, and the third wall 213 can be the bottom wall of the housing 215.

[0189] The first outer surface 2121 is a surface of the second wall 212 facing away from the interior of the housing 21 along the first direction. The second outer surface 2131 is a surface of the third wall 213 facing away from the interior of the housing 21 along the first direction.

[0190] Along the first direction, the second weak portion 2145 is disposed between the first weak portion 2144 and the first outer surface 2121. Alternatively, along the first direction, the second weak portion 2145 is disposed between the first weak portion 2144 and the second outer surface 2131. Alternatively, the pressure relief component 214 includes a plurality of second weak portions 2145, with some of the second weak portions 2145 being located between the first weak portion 2144 and the first outer surface 2121, and others being located between the first weak portion 2144 and the second outer surface 2131. Referring to FIG. 5 , in the embodiment shown in the figure, the pressure relief component 214 includes two second weak portions 2145, with one second weak portion 2145 being located between the first weak portion 2144 and the first outer surface 2121, and the other second weak portion 2145 being located between the first weak portion 2144 and the second outer surface 2131.

[0191] When a second weak portion 2145 is provided between the first weak portion 2144 and the first outer surface 2121, the second weak portion 2145 is closer to the first outer surface 2121 than the first weak portion 2144, and the stiffness at the location of the first weak portion 2144 is smaller than the stiffness at the location of the second weak portion 2145. When the battery cell 20 is depressurized, the deformation of the pressure relief component 214 at the location of the first weak portion 2144 is greater than the deformation of the pressure relief component 214 at the location of the second weak portion 2145, which is conducive to causing the first weak portion 2144 to rupture before the second weak portion 2145, so that the predetermined pressure relief area 21431 can be flipped open under the guidance of the second weak portion 2145. Similarly, when a second weak portion 2145 is provided between the first weak portion 2144 and the second outer surface 2131, the second weak portion 2145 is closer to the second outer surface 2131 than the first weak portion 2144, and the stiffness at the location of the first weak portion 2144 is smaller than the stiffness at the location of the second weak portion 2145. When the battery cell 20 is depressurized, the deformation of the pressure relief component 214 at the location of the first weak portion 2144 is greater than the deformation of the pressure relief component 214 at the location of the second weak portion 2145, which is conducive to causing the first weak portion 2144 to crack before the second weak portion 2145, so that the predetermined pressure relief area 21431 can be flipped open under the guidance of the second weak portion 2145.

[0192] Referring to Figures 3, 4, 5, 6, and 7, in some embodiments, the pressure relief component 214 is provided with a first groove 2146 and a second groove 21451. The pressure relief component 214 forms a first weakened portion 2144 in the region where the first groove 2146 is provided, and a second weakened portion 2145 in the region where the second groove 21451 is provided. The first groove 2146 includes at least one groove segment, and the pressure relief component 214 forms a weakened portion in the region where the groove segment is provided. The weakened portion has a first cross-sectional area perpendicular to its extension direction, a first width at the bottom of the groove segment, and a first thickness at the bottom of the groove segment. The first cross-sectional area is equal to the product of the first width and the first thickness. The second weakened portion 2145 has a second cross-sectional area perpendicular to its extension direction, a second width at the bottom of the second groove 21451, and a second thickness at the bottom of the second weakened portion 2145. The second cross-sectional area is equal to the product of the second width and the second thickness.

[0193] The first groove 2146 and the second groove 21451 can be disposed on the same side of the pressure relief component 214, or on opposite sides of the pressure relief component 214. Along the thickness direction of the first wall 211, the pressure relief component 214 has a first surface 2111 and a second surface 2112 that are disposed opposite each other, wherein the first surface 2111 faces away from the interior of the housing 21, and the second surface 2112 faces the interior of the housing 21. The first groove 2146 and the second groove 21451 can both be disposed on the first surface 2111, or both on the second surface 2112. In this case, the first groove 2146 and the second groove 21451 are disposed on the same side of the pressure relief component 214. One of the first groove 2146 and the second groove 21451 can be provided on the first surface 2111, and the other of the first groove 2146 and the second groove 21451 can be provided on the second surface 2112. In this case, the first groove 2146 and the second groove 21451 are provided on both sides of the pressure relief component 214. Alternatively, the first groove 2146 is provided on the first surface 2111, and the second groove 21451 is provided on the second surface 2112.

[0194] The first groove 2146 and the second groove 21451 can be formed by various methods, such as stamping, cold heading, etc. For example, if the first groove 2146 is formed by stamping, the first groove 2146 can be stamped on the pressure relief component 214 along the direction from the first surface 2111 to the second surface 2112. For example, if the second groove 21451 is formed by stamping, the second groove 21451 can be stamped on the pressure relief component 214 along the direction from the second surface 2112 to the first surface 2111.

[0195] The first weak portion 2144 is the bottom wall of the first groove 2146, and the second weak portion 2145 is the bottom wall of the second groove 21451. The first groove 2146 includes at least one groove segment, and the weak segment is the bottom wall of the groove segment. The weak segments correspond one to one.

[0196] The first weak portion 2144 includes at least one weak segment, which is a linear structure. The first cross-sectional area represents the cross-sectional area perpendicular to the extension direction of the weak segment. Referring to Figure 7 , a honeycomb-shaped fill pattern is used to illustrate a cross-sectional area perpendicular to the extension direction of the weak segment. The area filled by the honeycomb-shaped fill pattern is the first cross-sectional area, also known as S1.

[0197] In some embodiments, the position of the weak section can be determined by tomography, and the cross-sectional area of ​​the cross section perpendicular to the extension direction of the weak section can be determined, that is, S1 can be obtained by tomography.

[0198] The first width is the minimum width of the bottom surface of the groove segment. Please refer to Figure 7, which shows the first width, which is a1. It should be noted that the ends of the groove segment generally have rounded corners. When measuring the first width, the minimum width of the groove segment should be measured outside the rounded corner transition area, that is, the measurement should be avoided at the rounded corner transition area.

[0199] The first thickness is the minimum thickness of the weak section. Referring to FIG. 7 , FIG. 7 illustrates the first thickness, which is h1. The first thickness can be determined by measuring the difference between the thickness of the pressure relief component 214 and the depth of the groove, or by tomography, or by measuring after the weak section has ruptured.

[0200] The first cross-sectional area is equal to the product of the first width and the first thickness, that is, S1 = a1 × h1. The first cross-sectional area can be calculated by measuring the first width and the first thickness. It should be noted that when calculating the first cross-sectional area, the area where the groove section has rounded corners should be avoided.

[0201] The second weak portion 2145 can be a linear structure. The second cross-sectional area represents the cross-sectional area perpendicular to the extension direction of the second weak portion 2145. Referring to FIG6 , FIG6 illustrates a cross-sectional area perpendicular to the extension direction of the second weak portion 2145 using a mesh-like fill pattern. The area filled by the mesh-like fill pattern is the second cross-sectional area, or S2.

[0202] In some embodiments, the position of the second weak portion 2145 can be determined by tomography, and the cross-sectional area of ​​the cross section perpendicular to the extension direction of the second weak portion 2145 can be determined, that is, S2 can be obtained by tomography.

[0203] The second width is the minimum width of the bottom surface of the second groove 21451. Please refer to Figure 6 , which shows the second width, which is labeled a2. It should be noted that the ends of the second groove 21451 typically have rounded corners. When measuring the second width, the minimum width of the second groove 21451 outside the rounded corner transition area should be measured, that is, the measurement should be avoided at the rounded corner transition area.

[0204] The second thickness is the minimum thickness of the second weak portion 2145. Referring to Figure 6 , the second thickness is indicated as h2. The second thickness can be determined by the difference between the thickness of the pressure relief component 214 and the depth of the second groove 21451, or by tomography, or by measuring the second weak portion 2145 after sectioning.

[0205] The second cross-sectional area is equal to the product of the second width and the second thickness, that is, S2 = a2 × h2. The second cross-sectional area can be calculated by measuring the second width and the second thickness. It should be noted that when calculating the second cross-sectional area, the area where the rounded corners of the second notch groove transition should be avoided.

[0206] The first weak portion 2144 and the second weak portion 2145 are formed by providing a first groove 2146 and a second groove 21451 in the pressure relief component 214, which is simple, convenient, and low-cost. The first cross-sectional area is equal to the product of the first width and the first thickness, that is, the cross-section of the weak portion perpendicular to its extension direction is rectangular. When measuring the first cross-sectional area, the first width and the first thickness can be measured to calculate the first cross-sectional area. The second cross-sectional area is equal to the product of the second width and the second thickness, that is, the cross-section of the second weak portion 2145 perpendicular to its extension direction is rectangular. When measuring the second cross-sectional area, the second width and the second thickness can be measured to calculate the second cross-sectional area.

[0207] 3 , 4 , 5 , 6 and 7 , in some embodiments, the first width is a1, satisfying: 0.01 mm ≤ a1 ≤ 0.8 mm.

[0208] The value of the first width can be a1=0.01mm, 0.03mm, 0.05mm, 0.08mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, etc.

[0209] When a1 ≥ 0.01 mm, the first width is relatively large, which can reduce the risk of the weak section rupturing due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When a1 ≤ 0.8 mm, the first width is not excessively large, thereby facilitating the timely rupture of the weak section upon pressure relief from the battery cell 20, thereby improving the timeliness of pressure relief from the battery cell 20. Therefore, when 0.01 mm ≤ a1 ≤ 0.8 mm, the first width is moderately large, making the weak section less susceptible to rupture due to changes in air pressure within the battery cell 20, while still allowing it to rupture promptly upon pressure relief from the battery cell 20, thereby improving the timeliness of pressure relief from the battery cell 20.

[0210] In some embodiments, 0.05 mm ≤ a1 ≤ 0.5 mm.

[0211] The value of the first width can be a1=0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.42mm, 0.45mm, 0.48mm, 0.5mm, etc.

[0212] When a1 ≥ 0.05 mm, the first width is larger, further reducing the risk of the weak section rupturing due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When a1 ≤ 0.5 mm, this facilitates more timely rupturing of the weak section during pressure relief from the battery cell 20, thereby improving the timeliness of pressure relief from the battery cell 20. Therefore, when 0.05 mm ≤ a1 ≤ 0.5 mm, both the reliability and timeliness of pressure relief from the battery cell 20 are better balanced.

[0213] Optionally, 0.1mm≤a1≤0.3mm.

[0214] The value of the first width can be a1=0.1mm, 0.11m, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, etc.

[0215] When a1 ≥ 0.1 mm, the first width is larger, further reducing the risk of the weak section rupturing due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When a1 ≤ 0.3 mm, this facilitates more timely rupturing of the weak section during pressure relief from the battery cell 20, thereby improving the timeliness of pressure relief from the battery cell 20. Therefore, when 0.1 mm ≤ a1 ≤ 0.3 mm, both the reliability and timeliness of pressure relief from the battery cell 20 are better balanced.

[0216] In some embodiments, the first thickness is h1, satisfying: 0.02 mm ≤ h1 ≤ 1 mm.

[0217] The value of the first thickness can be h1 = 0.02mm, 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, etc.

[0218] When h1 ≥ 0.02 mm, the first thickness is relatively large, which can reduce the risk of the weak section rupturing due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When h1 ≤ 1 mm, the first thickness is not excessively large, thereby facilitating the timely rupture of the weak section upon pressure relief from the battery cell 20, thereby improving the timeliness of pressure relief from the battery cell 20. Therefore, when 0.02 mm ≤ h1 ≤ 1 mm, the first thickness is moderately large, making the weak section less susceptible to rupture due to changes in air pressure within the battery cell 20, while still allowing it to rupture promptly upon pressure relief from the battery cell 20, thereby improving the timeliness of pressure relief from the battery cell 20.

[0219] In some embodiments, 0.04 mm ≤ h1 ≤ 0.6 mm.

[0220] The value of the first thickness can be h1 = 0.04mm, 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.42mm, 0.45mm, 0.48mm, 0.5mm, 0.52mm, 0.55mm, 0.58mm, 0.6mm, etc.

[0221] When h1 ≥ 0.04 mm, the first thickness is greater, further reducing the risk of the weak section rupturing due to pressure changes within the battery cell 20, thereby improving the reliability of the battery cell 20. When h1 ≤ 0.6 mm, this facilitates more timely rupture of the weak section during pressure relief from the battery cell 20, thereby improving the timeliness of pressure relief from the battery cell 20. Therefore, when 0.04 mm ≤ h1 ≤ 0.6 mm, both the reliability and timeliness of pressure relief from the battery cell 20 are better balanced.

[0222] Optionally, 0.08mm≤h1≤0.4mm.

[0223] The value of the first thickness can be h1 = 0.08mm, 0.09mm, 0.1mm, 0.11m, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, etc.

[0224] When h1 ≥ 0.08 mm, the first thickness is greater, further reducing the risk of the weak section rupturing due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When h1 ≤ 0.4 mm, this facilitates more timely rupture of the weak section during pressure relief from the battery cell 20, thereby improving the timeliness of pressure relief from the battery cell 20. Therefore, when 0.08 mm ≤ h1 ≤ 0.4 mm, both the reliability and timeliness of pressure relief from the battery cell 20 are better balanced.

[0225] In some embodiments, the second width is a2, satisfying: 0.01 mm ≤ a2 ≤ 0.5 mm.

[0226] The value of the second width can be a2 = 0.01 mm, 0.03 mm, 0.05 mm, 0.08 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.

[0227] When a2 ≥ 0.01 mm, the second width is relatively large, reducing the risk of the second weak portion 2145 cracking due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When a2 ≤ 0.5 mm, the second width is not excessively large, thereby reducing resistance to the rotation of the predetermined pressure relief area 21431, facilitating rapid rotation and opening of the predetermined pressure relief area 21431, and improving the timeliness of pressure relief in the battery cell 20. Therefore, when 0.01 mm ≤ a2 ≤ 0.5 mm, the second width is moderately large, making the second weak portion 2145 less susceptible to cracking due to changes in air pressure within the battery cell 20 while facilitating rapid rotation and opening of the predetermined pressure relief area 21431, thereby improving the timeliness of pressure relief in the battery cell 20.

[0228] In some embodiments, 0.04 mm ≤ a2 ≤ 0.3 mm.

[0229] The value of the second width can be a2 = 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, etc.

[0230] When a2 ≥ 0.04 mm, the second width is larger, further reducing the risk of cracking of the second weak portion 2145 due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When a2 ≤ 0.3 mm, the resistance to the predetermined pressure relief area 21431 turning is reduced, facilitating rapid opening of the predetermined pressure relief area 21431, thereby improving the timeliness of pressure relief in the battery cell 20. Therefore, when 0.04 mm ≤ a2 ≤ 0.3 mm, both the reliability and timeliness of pressure relief in the battery cell 20 are better balanced.

[0231] Optionally, 0.06mm≤a2≤0.15mm.

[0232] The value of the second width can be a2 = 0.06mm, 0.065mm, 0.07mm, 0.075mm, 0.08mm, 0.085mm, 0.09mm, 0.095mm, 0.1mm, 0.105mm, 0.11m, 0.115mm, 0.12mm, 0.125mm, 0.13mm, 0.135mm, 0.14mm, 0.145mm, 0.15mm.

[0233] When a2 ≥ 0.06 mm, the second width is larger, further reducing the risk of cracking the second weak portion 2145 due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When a2 ≤ 0.15 mm, the resistance to the predetermined pressure relief area 21431 turning is reduced, facilitating rapid opening of the predetermined pressure relief area 21431, thereby improving the timeliness of pressure relief in the battery cell 20. Therefore, when 0.06 mm ≤ a2 ≤ 0.15 mm, both the reliability and timeliness of pressure relief in the battery cell 20 are better balanced.

[0234] In some embodiments, the second thickness is h2, satisfying: 0.1 mm ≤ h2 ≤ 2 mm.

[0235] The value of the second thickness can be h2 = 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, etc.

[0236] When h2 ≥ 0.1 mm, the second thickness is relatively large, reducing the risk of the second weak portion 2145 cracking due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When h2 ≤ 2 mm, the second thickness is not excessively large, thereby reducing resistance to the rotation of the predetermined pressure relief area 21431, facilitating rapid rotation and opening of the predetermined pressure relief area 21431, and improving the timeliness of pressure relief in the battery cell 20. Therefore, when 0.1 mm ≤ h2 ≤ 2 mm, the second thickness is moderately large, making the second weak portion 2145 less susceptible to cracking due to changes in air pressure within the battery cell 20 while facilitating rapid rotation and opening of the predetermined pressure relief area 21431, thereby improving the timeliness of pressure relief in the battery cell 20.

[0237] In some embodiments, 0.2 mm ≤ h2 ≤ 1.5 mm.

[0238] The value of the second thickness can be h2 = 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, etc.

[0239] When h2 ≥ 0.2 mm, the second thickness is greater, further reducing the risk of cracking of the second weak portion 2145 due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When h2 ≤ 1.5 mm, the resistance to the predetermined pressure relief area 21431 turning is reduced, facilitating rapid opening of the predetermined pressure relief area 21431, thereby improving the timeliness of pressure relief in the battery cell 20. Therefore, when 0.2 mm ≤ h2 ≤ 1.5 mm, a better balance is achieved between the reliability and timeliness of pressure relief in the battery cell 20.

[0240] Optionally, 0.5mm≤h2≤1mm.

[0241] The value of the second thickness can be h2 = 0.5mm, 0.52mm, 0.55mm, 0.58mm, 0.6mm, 0.62mm, 0.65mm, 0.68mm, 0.7mm, 0.72mm, 0.75mm, 0.78mm, 0.8mm, 0.82mm, 0.85mm, 0.88mm, 0.9mm, 0.92mm, 0.95mm, 0.98mm, 1mm, etc.

[0242] When h2 ≥ 0.5 mm, the second thickness is greater, further reducing the risk of cracking of the second weak portion 2145 due to changes in air pressure within the battery cell 20, thereby improving the reliability of the battery cell 20. When h2 ≤ 1 mm, the resistance to the rotation of the predetermined pressure relief area 21431 is reduced, facilitating rapid rotation and opening of the predetermined pressure relief area 21431, thereby improving the timeliness of pressure relief in the battery cell 20. Therefore, when 0.5 mm ≤ h2 ≤ 1 mm, a better balance is achieved between the reliability and timeliness of pressure relief in the battery cell 20.

[0243] Referring to Figures 3, 4, 5, 6 and 7, in some embodiments, along the first direction, the distance between the first outer surface 2121 and the second outer surface 2131 is a first distance, the minimum distance between the first weak portion 2144 and the first outer surface 2121 is a second distance, the minimum distance between the first weak portion 2144 and the second outer surface 2131 is a third distance, and the ratio of the difference between the second distance and the third distance to the first distance is greater than or equal to 0 and less than or equal to 0.1.

[0244] The first distance represents the distance between the first outer surface 2121 and the second outer surface 2131 along the first direction. Referring to FIG5 , the first distance is marked as L. During measurement, multiple measurements may be taken to obtain an average value.

[0245] The second distance represents the minimum distance between the first weak portion 2144 and the first outer surface 2121 along the first direction. Referring to FIG. 5 , the second distance is indicated as L1. During measurement, the distance between the location of the first weak portion 2144 closest to the first outer surface 2121 and the first outer surface 2121 can be measured. Multiple measurements can also be taken and averaged to reduce measurement errors.

[0246] The third distance represents the minimum distance between the first weak portion 2144 and the second outer surface 2131 along the first direction. Referring to Figure 5 , the third distance is shown, with the second distance being L2. During measurement, the distance between the location of the first weak portion 2144 closest to the second outer surface 2131 and the second outer surface 2131 can be measured. Multiple measurements can also be taken and averaged to reduce measurement errors.

[0247] The difference between the second distance and the third distance represents a result of subtracting a smaller one of the second distance and the third distance from the larger one of the second distance and the third distance.

[0248] “The ratio of the difference between the second distance and the third distance to the first distance is greater than or equal to 0 and less than or equal to 0.1”, that is, 0≤|L1-L2| / L≤0.1.

[0249] 0≤|L1-L2| / L≤0.1 indicates that the distance between the first weak portion 2144 and the first outer surface 2121 and the distance between the first weak portion 2144 and the second outer surface 2131 are relatively small, that is, the first weak portion 2144 is approximately located in the middle of the first wall 211 .

[0250] The value of |L1-L2| / L can be: |L1-L2| / L=0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc.

[0251] When 0≤|L1-L2| / L≤0.1, the position of the first weak portion 2144 is close to the middle position of the first wall 211 along the first direction. The stiffness of the middle position of the first wall 211 along the first direction is relatively small. When the battery cell 20 is depressurized, the middle position of the first wall 211 along the first direction will undergo a large deformation, which is conducive to causing the first weak portion 2144 to crack before the second weak portion 2145, so that the predetermined pressure relief area 21431 can be flipped open under the guidance of the second weak portion 2145, which is conducive to improving the reliability of the battery cell 20.

[0252] In some embodiments, the first wall 211 has a third outer surface 2113 facing away from the interior of the housing 21 , and along the thickness direction of the first wall 211 , the projection of the first weak portion 2144 covers the center of the third outer surface 2113 .

[0253] 6 and 7 , the thickness direction of the first wall 211 is the Y direction shown in the figures. The first direction intersects the thickness direction of the first wall 211. In the embodiment shown in FIG6 and FIG7 , the first direction is perpendicular to the thickness direction of the first wall 211.

[0254] Along the thickness direction of the first wall 211, the pressure relief component 214 has a first surface 2111 and a second surface 2112 that are oppositely disposed, wherein the first surface 2111 faces away from the interior of the housing 21, and the second surface 2112 faces the interior of the housing 21. When the pressure relief component 214 and the first wall 211 are integrally formed, the first surface 2111 serves as the third outer surface 2113 described above.

[0255] For example, if the third outer surface 2113 is a rectangle, the center point of the third outer surface 2113 is the intersection of the diagonals of the rectangle. For example, if the third outer surface 2113 is a circle, the center point of the third outer surface 2113 is the center of the circle.

[0256] The center point of the third outer surface 2113 may be located at an edge of the projection of the first weak portion 2144 on the third outer surface 2113. For example, if the first weak portion 2144 is a linear structure, the center point of the third outer surface 2113 may be located at one end of the projection of the first weak portion 2144 on the third outer surface 2113. The center point of the third outer surface 2113 may be located in the middle of the projection of the first weak portion 2144 on the third outer surface 2113. For example, if the first weak portion 2144 is a linear structure, the center point of the third outer surface 2113 may be located at the midpoint of the projection of the first weak portion 2144 on the third outer surface 2113.

[0257] Along the thickness direction of the first wall 211, the projection of the first weak portion 2144 covers the center of the third outer surface 2113. The position of the first weak portion 2144 is closer to the middle position of the first wall 211 along the first direction, which is more conducive to the first weak portion 2144 to crack before the second weak portion 2145, so that the predetermined pressure relief area 21431 can be flipped open under the guidance of the second weak portion 2145, which is beneficial to improving the reliability of the battery cell 20.

[0258] Referring to Figures 3, 4, 5, 6, and 7, in some embodiments, a second weak portion 2145 is disposed between the first weak portion 2144 and the first outer surface 2121 along the first direction. Along the first direction, the distance between the first outer surface 2121 and the second outer surface 2131 is a first distance, the minimum distance between the second weak portion 2145 and the first outer surface 2121 is a fourth distance, and the minimum distance between the second weak portion 2145 and the second outer surface 2131 is a fifth distance. The first weak portion 2144 includes at least one weak segment, the cross-sectional area of ​​the weak segment perpendicular to its extension direction being a first cross-sectional area, and the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction being a second cross-sectional area. When the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or equal to 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1.5.

[0259] The fourth distance represents the minimum distance between the second weak portion 2145 and the first outer surface 2121 along the first direction. Referring to FIG. 5 , the fourth distance is indicated as L3. During measurement, the distance between the location of the second weak portion 2145 closest to the first outer surface 2121 and the first outer surface 2121 can be measured. Multiple measurements can be taken and averaged to reduce measurement errors.

[0260] The fifth distance represents the minimum distance between the second weak portion 2145 and the second outer surface 2131. Referring to Figure 5 , the fifth distance is labeled L4. During measurement, the distance between the second weak portion 2145 closest to the second outer surface 2131 and the second outer surface 2131 can be measured. Multiple measurements can be taken and averaged to reduce measurement errors.

[0261] The difference between the fifth distance and the fourth distance is the result of subtracting the smaller one of the fifth distance and the fourth distance from the larger one of the fifth distance and the fourth distance.

[0262] "When the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or equal to 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1.5." This means that when |L4-L3| / L≥0.4, 0.7<S2 / S1≤1.5. |L4-L3| / L≥0.4 indicates that there is a significant difference between the distance from the second weak portion 2145 to the first outer surface 2121 and the distance from the second weak portion 2145 to the second outer surface 2131. This means that the second weak portion 2145 is positioned away from the center of the first wall 211 and closer to the first outer surface 2121.

[0263] The first weak portion 2144 includes at least one weak segment, which is a linear structure. S1 represents the cross-sectional area of ​​the cross section perpendicular to the direction of extension of the weak segment. The cross-sectional area of ​​the weak segment perpendicular to its extension direction has a significant impact on whether the weak segment is prone to cleavage. The larger the cross-sectional area of ​​the weak segment perpendicular to its extension direction, the more difficult it is to cleave. The smaller the cross-sectional area of ​​the weak segment perpendicular to its extension direction, the more likely it is to cleave.

[0264] The second weak portion 2145 can be a linear structure. S2 represents the cross-sectional area of ​​the cross section perpendicular to the extension direction of the second weak portion 2145. The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction has a significant impact on whether the second weak portion 2145 is susceptible to cleavage. The larger the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction, the less susceptible the second weak portion 2145 is to cleavage. The smaller the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction, the more susceptible the second weak portion 2145 is to cleavage.

[0265] By restricting the relationship between S1 and S2 , the risk of the second weak portion 2145 breaking before the first weak portion 2144 when the battery cell 20 is depressurized can be reduced.

[0266] When |L4-L3| / L≥0.4, the value of S2 / S1 can be: S2 / S1=0.71, 0.75, 0.78, 0.8, 0.83, 0.85, 0.9, 0.93, 0.95, 1, 1.05, 1.11, 1.12, 1.15, 1.17, 1.2, 1.24, 1.25, 1.3, 1.35, 1.38, 1.4, 1.44, 1.47, 1.5, etc.

[0267] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to Comparative Examples 1-6 and Examples 1-17. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually merely illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0268] Example 1

[0269] 1) Preparation of positive electrode

[0270] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are prepared into positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the solid content of LiNi 0.7 Co 0.1 Mn 0.1 The mass ratio of O2, Super P, and PVDF is 8:1:1. The positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil and dried at 85°C and then cold pressed. Then, it is trimmed, cut, and striped, and then dried under vacuum conditions at 85°C for 4 hours to make the positive electrode sheet.

[0271] 2) Preparation of negative electrode sheet

[0272] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene-butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry is 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC, and adhesive styrene-butadiene rubber (SBR) in the solid components is 88:7:3:2. The negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C. Then, it is cold pressed, trimmed, cut into pieces, and slit, and then dried under vacuum conditions at 120°C for 12 hours to prepare a negative electrode sheet.

[0273] 3) Preparation of electrolyte

[0274] In an argon atmosphere glove box (H2O < 0.1ppm, O2 < 0.1ppm), the fully dried electrolyte salt LiPF6 was dissolved in a mixed solvent (the mixed solvent included ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 50:50), and after mixing evenly, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0275] 4) Isolation parts

[0276] A 16 μm polyethylene film was used as a separator.

[0277] 5) Preparation of battery cell 20

[0278] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrode sheets to isolate the positive and negative electrodes, and the electrode assembly 22 is wound to obtain the electrode assembly 22. The electrode assembly 22 is placed in an aluminum shell 21, and the prepared electrolyte is injected into the dried shell 21. The battery cell 20 is prepared by packaging, standing, forming, shaping, and capacity testing. A first weak portion 2144 and a second weak portion 2145 are formed on the first wall 211 of the shell 21 of the battery cell 20. The outer shell 21 of the battery cell 20 is a rectangular parallelepiped structure. The shell 215 of the outer shell 21 has an opening 2151 at one end. The wall of the shell 215 opposite the end cap 216 is a first wall 211. The first wall 211 is a rectangular wall and is provided with a first groove 2146 and a second groove 21451. The first wall 211 forms a first weak portion 2144 in the area where the first groove 2146 is provided, and a second weak portion 2145 in the area where the second groove 21451 is provided. Along the first direction, the second weak portion 2145 is provided between the first weak portion 2144 and the first outer surface 2121. Among them, the first groove 2146 is an "H"-shaped structure, that is, the first groove 2146 includes a first groove section 2143a, a second groove section 2143b and a third groove section 2143c. The first groove section 2143a and the third groove section 2143c are arranged opposite to each other and both extend along the first direction. The second groove section 2143b is connected between the first groove section 2143a and the third groove section 2143c, and the second groove section 2143b is located in the middle of the first wall 211 in the first direction. The thickness of the battery cell 20 is 39 mm, the width is 203 mm, the shoulder height (the dimension of the shell 21 in the height direction) is 122.7 mm, and the capacity is 185 Ah.

[0279] The distance L between the first outer surface 2121 and the second outer surface 2131, the minimum distance L3 between the second weak portion 2145 and the first outer surface 2121, the minimum distance L4 between the second weak portion 2145 and the second outer surface 2131, the width D1 of the bottom surface of the groove section, the thickness H1 of the weak section, the width D2 of the bottom surface of the second groove 21451 and the thickness H2 of the second weak portion 2145 are all obtained through tomography and then measured by software.

[0280] The preparation methods of the battery cells 20 of Comparative Examples 1 to 4 and Examples 2 to 10 are the same as those of Example 1, except that the difference between the minimum distance L4 between the second weak portion 2145 and the second outer surface 2131 and the minimum distance L3 between the second weak portion 2145 and the first outer surface 2121, the cross-sectional area S1 of the weak section perpendicular to its extension direction, and the cross-sectional area S2 of the second weak portion 2145 perpendicular to its extension direction are different. In Comparative Examples 1 to 4 and Examples 1 to 10, the first direction is the width direction of the first wall 211, and the specific situation is shown in Tables 1 to 2.

[0281] The preparation methods of the battery cells 20 of Comparative Examples 5 to 6 and Examples 11 to 17 are the same as those of Example 1, except that the difference between the minimum distance L4 between the second weak portion 2145 and the second outer surface 2131 and the minimum distance L3 between the second weak portion 2145 and the first outer surface 2121, the cross-sectional area S1 of the weak section perpendicular to its extension direction, and the cross-sectional area S2 of the second weak portion 2145 perpendicular to its extension direction are different. In Comparative Examples 5 to 6 and Examples 11 to 17, the first direction is the longitudinal direction of the first wall 211, and the specific situation is shown in Table 3.

[0282] The battery cell 20 needs to be pre-treated before testing: ① Drill a hole at the injection hole of the battery cell 20; ② Insert the hose 10mm into the battery cell 20 from the injection hole; ③ Squeeze the AB glue onto cardboard and mix it evenly; ④ Apply the evenly mixed AB glue around the interface between the hose and the battery cell 20 (Note: There must be no bubbles or dirt on the bonding surface) and let it stand for 30 minutes.

[0283] During the blasting test, a steel clamp was used to clamp the two large surfaces of the battery cell 20 (when the first direction is the width of the first wall 211, the two large surfaces are the first outer surface 2121 and the second outer surface 2131, respectively) with a preload of 3000N, simulating the restrained state of the battery cell 20 in an actual module or battery pack. Simultaneously, the pressure relief component 214 was videotaped throughout the test to observe its detonation position and the flipping movement of the predetermined pressure relief area 21431. Before the test, the detonation pressure testing system was connected to the battery cell 20 via a flexible hose. During the test, the detonation pressure testing system inflated the battery cell 20 at a rate of 0.3 MPa / s and monitored the intake pressure of the battery cell 20 in real time. Inflation ceased when the intake pressure dropped by more than 0.02 MPa. Generally, the intake pressure curve shows an increasing trend. When the intake pressure reaches the detonation pressure of the battery cell 20, it suddenly drops to 0. The maximum value of the curve at this time is the detonation pressure of the battery cell 20.

[0284] The experimental results of Comparative Examples 1 to 6 and Examples 1 to 17 are shown in Tables 1 to 3 below:

[0285] Table 1

[0286] Table 2

[0287] Table 3

[0288] Referring to Tables 1 and 2, as shown in Comparative Examples 1 and 3, |L4-L3| / L≥0.4, but S2 / S1≤0.7. In this case, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is small. When the battery cell 20 is depressurized, the second weak portion 2145 ruptures before the first weak portion 2144.

[0289] As shown in Comparative Examples 2 and 4, |L4-L3| / L≥0.4, but S2 / S1>1.5. In this case, the second weak portion 2145 is close to the first outer surface 2121, and the stiffness of the first wall 211 at the second weak portion 2145 is significantly different from the stiffness of the first wall 211 at the first weak portion 2144. The stiffness has a significant impact on the cracking of the first and second weak portions 2144, 2145. Furthermore, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is large, and the strength of the pressure relief component 214 at the second weak portion 2145 is greater, which significantly hinders the flipping and opening of the predetermined pressure relief area 21431, making it difficult for the predetermined pressure relief area 21431 to flip and open under the action of the fluid medium. In engineering, it is expected that the detonation position of the pressure relief component 214 is located at the first weak portion 2144, and the second weak portion 2145 only serves as a guide. When the battery cell 20 is used in a project, there is an upper and lower limit requirement for the detonation pressure (0.9±0.2MPa), |L4-L3| / L≥0.4. If S2 / S1>1.5, the detonation pressure will be higher than the upper limit of the detonation pressure desired by the project.

[0290] As shown in Examples 1 to 10, |L4-L3| / L≥0.4, 0.7<S2 / S1≤1.5, which not only enables the detonation position of the pressure relief component 214 to be located at the first weak portion 2144, but also allows the detonation pressure to meet engineering expectations.

[0291] When |L4 - L3| / L ≥ 0.4, the second weak portion 2145 deviates significantly from the middle position of the first wall 211 along its width. In this case, the second weak portion 2145 is closer to the first outer surface 2121. The stiffness of the first wall 211 at the second weak portion 2145 differs significantly from the stiffness of the first wall 211 at the first weak portion 2144. This stiffness significantly impacts the cracking of the first and second weak portions 2144, 2145. If the effect of stiffness on the first and second weak portions 2144, 2145 is not considered, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction only needs to be greater than the cross-sectional area of ​​the weak section perpendicular to its extension direction, that is, S2 / S1 > 1. This allows the first weak portion 2144 to open and release pressure before the second weak portion 2145, and the second weak portion 2145 serves to guide the predetermined pressure relief zone 21431. However, considering that stiffness has a significant impact on the rupture of the first weak portion 2144 and the second weak portion 2145 (given the same cross-sectional area, the second weak portion 2145 is more difficult to rupture than the first weak portion 2144, and therefore, the cross-sectional area of ​​the second weak portion 2145 can be set to be smaller), when 0.7 < S2 / S1 ≤ 1, the first weak portion 2144 can also be opened to release pressure before the second weak portion 2145, and the second weak portion 2145 serves to guide the predetermined pressure relief area 21431. Similarly, because stiffness has a significant impact on the rupture of the first weak portion 2144 and the second weak portion 2145, when S2 / S1 ≤ 1.5, the strength of the pressure relief component 214 at the second weak portion 2145 is relatively low, thereby minimizing the obstruction to the flipping and opening of the predetermined pressure relief area 21431, making it easier for the predetermined pressure relief area 21431 to flip and open under the action of the fluid medium.

[0292] 3 , 4 , 5 , 6 and 7 , in some embodiments, the first wall 211 has a third outer surface 2113 facing away from the interior of the housing 21 . The third outer surface 2113 is rectangular, and the first direction is parallel to the width direction of the rectangle.

[0293] “The first direction is parallel to the width direction of the rectangle” can also be understood as the first direction being the width direction of the third outer surface 2113 .

[0294] The first weak portion 2144 and the second weak portion 2145 are arranged along the width direction of the third outer surface 2113. The first weak portion 2144 is closer to the middle position of the first wall 211 along the width direction than the second weak portion 2145, and the second weak portion 2145 is closer to the edge position of the first wall 211 along the width direction than the first weak portion 2144. The stiffness has a greater impact on the cracking of the first weak portion 2144 and the second weak portion 2145.

[0295] Referring to Figures 3, 4, 5, 6, and 7, in some embodiments, the pressure relief component 214 is provided with a first groove 2146 and a second groove 21451. The pressure relief component 214 forms a first weakened portion 2144 in the region where the first groove 2146 is provided, and a second weakened portion 2145 in the region where the second groove 21451 is provided. The first groove 2146 includes at least one groove segment, and the pressure relief component 214 forms a weakened portion in the region where the groove segment is provided. The weakened portion has a first cross-sectional area perpendicular to its extension direction, a first width at the bottom of the groove segment, and a first thickness at the bottom of the groove segment. The first cross-sectional area is equal to the product of the first width and the first thickness. The second weakened portion 2145 has a second cross-sectional area perpendicular to its extension direction, a second groove 21451 has a second width at the bottom, and a second thickness at the bottom of the second weakened portion 2145. The second cross-sectional area is equal to the product of the second width and the second thickness. The second thickness is greater than or equal to the first thickness, and the second width is less than or equal to the first width.

[0296] “The second thickness is greater than or equal to the first thickness, and the second width is less than or equal to the first width” means h2≥h1, a2≤a1.

[0297] By making the second thickness greater than or equal to the first thickness and the second width less than or equal to the first width, not only can the second weak portion 2145 better guide the predetermined pressure relief area 21431 to open, but also the second width can be made as small as possible while satisfying the condition that when the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1.5, thereby reducing the area occupied by the second groove 21451 on the third outer surface 2113 of the pressure relief component 214.

[0298] Referring to Figures 3, 4, 5, 6, and 7, in some embodiments, a second weak portion 2145 is disposed between the first weak portion 2144 and the first outer surface 2121 along the first direction. Along the first direction, the distance between the first outer surface 2121 and the second outer surface 2131 is a first distance, the minimum distance between the second weak portion 2145 and the first outer surface 2121 is a fourth distance, and the minimum distance between the second weak portion 2145 and the second outer surface 2131 is a fifth distance. The first weak portion 2144 includes at least one weak segment, the cross-sectional area of ​​the weak segment perpendicular to its extension direction being a first cross-sectional area, and the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction being a second cross-sectional area. When the ratio of the difference between the fifth distance and the fourth distance to the first distance is less than 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1.5 and less than or equal to 5.

[0299] “When the ratio of the difference between the fifth distance and the fourth distance to the first distance is less than 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1.5 and less than or equal to 5”, that is, when |L4-L3| / L<0.4, 1.5<S2 / S1≤5.

[0300] When |L4-L3| / L<0.4, the value of S2 / S1 can be: S2 / S1=1.53, 1.71, 1.8, 1.82, 1.83, 2, 2.13, 2.2, 2.5, 2.56, 2.8, 3, 3.31, 3.2, 3.4, 3.5, 3.8, 4, 4.08, 4.2, 4.5, 4.67, 4.8, 4.75, 5, etc.

[0301] Referring to Table 3, as shown in Comparative Example 5, |L4-L3| / L<0.4 and S2 / S1≤1.5, the second weak portion 2145 is located near the center of the first outer surface 2121. The stiffness of the first wall 211 at the second weak portion 2145 is similar to that at the first weak portion 2144. Therefore, the stiffness has little impact on the cracking of the first and second weak portions 2144, 2145. However, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is relatively small. Therefore, when the battery cell 20 is depressurized, the second weak portion 2145 will crack before the first weak portion 2144.

[0302] Referring to Table 3, as shown in Comparative Example 6, |L4-L3| / L<0.4, and S2 / S1>5, the second weak portion 2145 is located near the center of the first outer surface 2121. The stiffness of the first wall 211 at the second weak portion 2145 is similar to that at the first weak portion 2144, and the stiffness has little impact on the cracking of the first and second weak portions 2144, 2145. However, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is too large, and the strength of the pressure relief component 214 at the second weak portion 2145 is too great, significantly hindering the opening of the predetermined pressure relief area 21431, making it difficult for the predetermined pressure relief area 21431 to open under the influence of the fluid medium. In engineering, it is desirable that the detonation location of the pressure relief component 214 be located at the first weak portion 2144, with the second weak portion 2145 serving only as a guide. When the battery cell 20 is used in a project, there is an upper and lower limit requirement for the detonation pressure (0.9±0.2MPa). When |L4-L3| / L<0.4, if S2 / S1>5, the detonation pressure will be higher than the upper limit of the detonation pressure desired by the project.

[0303] As shown in Examples 11 to 17, |L4-L3| / L<0.4, 1.5<S2 / S1≤5, which not only enables the detonation position of the pressure relief component 214 to be located at the first weak portion 2144, but also allows the detonation pressure to meet engineering expectations.

[0304] When |L4-L3| / L<0.4, the second weak portion 2145 deviates less from the middle position of the first wall 211 along the first direction. At this point, the second weak portion 2145 is also closer to the middle position of the first wall 211 along the first direction. The stiffness of the first wall 211 at the second weak portion 2145 is slightly different from the stiffness of the first wall 211 at the first weak portion 2144. Therefore, the stiffness has a smaller impact on the cracking of the first and second weak portions 2144, 2145. When S2 / S1>1.5, the first weak portion 2144 can open and release pressure before the second weak portion 2145. The second weak portion 2145 guides the predetermined pressure relief zone 21431, reducing the risk of the second weak portion 2145 cracking before the first weak portion 2144. When S2 / S1≤5, the strength of the pressure relief component 214 at the second weak portion 2145 is relatively small, and the obstacle to the predetermined pressure relief area 21431 flipping open is relatively small, making it easier for the predetermined pressure relief area 21431 to flip open under the action of the fluid medium.

[0305] Please refer to Figure 8, which is a bottom view of the housing 21 of the battery cell 20 provided in some other embodiments of the present application. In some other embodiments, the first wall 211 has a third outer surface 2113 facing away from the interior of the housing 21. The third outer surface 2113 is rectangular, and the first direction is parallel to the length direction of the rectangle.

[0306] “The first direction is parallel to the length direction of the rectangle” can also be understood as the first direction being the length direction of the third outer surface 2113 .

[0307] The first weak portion 2144 and the second weak portion 2145 are arranged along the length direction of the third outer surface 2113. The first weak portion 2144 and the second weak portion 2145 are both closer to the middle position of the first wall 211 along the length direction, and the stiffness has less effect on the cracking of the first weak portion 2144 and the second weak portion 2145.

[0308] In some embodiments, a ratio of the second cross-sectional area to the first cross-sectional area is greater than or equal to 2.13 and less than or equal to 4.67.

[0309] “The ratio of the second cross-sectional area to the first cross-sectional area is greater than or equal to 2.13 and less than or equal to 4.67”, that is, when |L4-L3| / L<0.4, 2.13≤S2 / S1≤4.67.

[0310] When |L4-L3| / L<0.4, the value of S2 / S1 can be: S2 / S1=2.13, 2.15, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.67, etc.

[0311] Referring to Table 3, as shown in Examples 13 to 15, |L4-L3| / L<0.4, 2.13≤S2 / S1≤4.67, not only can the detonation position of the pressure relief component 214 be located at the first weak portion 2144, but the detonation pressure is closer to 0.9 MPa.

[0312] When S2 / S1 is ≥ 2.13, the first weak portion 2144 is more likely to open and release pressure before the second weak portion 2145. The second weak portion 2145 guides the predetermined pressure relief area 21431, further reducing the risk of the second weak portion 2145 rupturing before the first weak portion 2144. When S2 / S1 is ≤ 4.67, the strength of the pressure relief component 214 at the second weak portion 2145 is lower, minimizing the obstruction to the opening of the predetermined pressure relief area 21431, making it easier for the predetermined pressure relief area 21431 to open under the influence of the fluid medium.

[0313] Referring to Figures 3, 4, 5, 6, and 7, in some embodiments, the pressure relief component 214 is provided with a first groove 2146 and a second groove 21451. The pressure relief component 214 forms a first weakened portion 2144 in the region where the first groove 2146 is provided, and a second weakened portion 2145 in the region where the second groove 21451 is provided. The first groove 2146 includes at least one groove segment, and the pressure relief component 214 forms a weakened portion in the region where the groove segment is provided. The weakened portion has a first cross-sectional area perpendicular to its extension direction, a first width at the bottom of the groove segment, and a first thickness at the bottom of the groove segment. The first cross-sectional area is equal to the product of the first width and the first thickness. The second weakened portion 2145 has a second cross-sectional area perpendicular to its extension direction, a second groove 21451 has a second width at the bottom, and a second thickness at the bottom of the second weakened portion 2145. The second cross-sectional area is equal to the product of the second width and the second thickness. The second thickness is greater than or equal to the first thickness, and the second width is greater than or equal to the first width.

[0314] “The second thickness is greater than or equal to the first thickness, and the second width is greater than or equal to the first width” means h2≥h1, a2≥a1.

[0315] By making the second thickness greater than or equal to the first thickness and the second width greater than or equal to the first width, the influence of the stiffness variation of different regions of the first wall 211 on the cracking of the weak section and the second weak section 2145 can be further reduced, so that the weak section cracks when the battery cell 20 is depressurized, and the second weak section 2145 guides the flipping of the predetermined pressure relief area 21431. In some embodiments, the first cross-sectional area is S1, which satisfies: 0.0002mm 2 ≤S1≤0.8mm 2 .

[0316] The cross-sectional area of ​​the weak section perpendicular to its extension direction can be: S1 = 0.0002 mm 2 , 0.0005mm 2 , 0.001mm 2 , 0.0015mm 2 , 0.002mm 2 , 0.003mm 2 , 0.005mm 2 , 0.01mm 2 , 0.03mm 2 , 0.05mm 2 , 0.08mm 2 , 0.1mm 2 , 0.15mm 2 , 0.2mm 2 , 0.25mm 2 , 0.3mm 2 , 0.35mm 2 , 0.4mm 2 , 0.45mm 2 , 0.5mm 2 , 0.55mm 2 , 0.6mm 2 , 0.65mm 2 , 0.7mm 2 , 0.75mm 2 , 0.8mm 2 wait.

[0317] When S1≥0.0002mm 2 When S1≤0.8mm, the cross-sectional area of ​​the first weak section perpendicular to its extension direction is large, and it is not easy to crack when subjected to external impact, which is beneficial to improving the reliability of the battery cell 20. 2 When the cross-sectional area of ​​the first weak section perpendicular to its extension direction is not too large, when the internal pressure of the battery cell 20 reaches the detonation pressure, the first weak section is easy to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.8mm 2, which can take into account both resistance to external impact and easy opening and pressure relief when the internal pressure of the battery cell 20 reaches the detonation pressure.

[0318] Optionally, 0.002 mm 2 ≤S1≤0.3mm 2 .

[0319] The cross-sectional area of ​​the weak section perpendicular to its extension direction can be: S1 = 0.002 mm 2 , 0.005mm 2 , 0.008mm 2 , 0.01mm 2 , 0.015mm 2 , 0.02mm 2 , 0.025mm 2 , 0.03mm 2 , 0.05mm 2 , 0.08mm 2 , 0.1mm 2 , 0.12mm 2 , 0.15mm 2 , 0.18mm 2 , 0.2mm 2 , 0.22mm 2 , 0.25mm 2 , 0.28mm 2 , 0.3mm 2 wait.

[0320] When S1≥0.002mm 2 When S1≤0.3mm, the risk of the first weak section cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell 20. 2 When the internal pressure of the battery cell 20 reaches the detonation pressure, the first weak section is more likely to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.3mm 2 When the battery cell 20 is opened, it can better resist external impact and is easy to open and release pressure when the internal pressure of the battery cell 20 reaches the detonation pressure.

[0321] Optionally, 0.008 mm 2 ≤S1≤0.12mm 2 .

[0322] The cross-sectional area of ​​the weak section perpendicular to its extension direction can be: S1 = 0.008 mm 2 , 0.009mm 2 , 0.01mm 2 , 0.015mm 2, 0.02mm 2 , 0.025mm 2 , 0.03mm 2 , 0.035mm 2 , 0.04mm 2 , 0.045mm 2 , 0.05mm 2 , 0.055mm 2 , 0.06mm 2 , 0.07mm 2 , 0.075mm 2 , 0.08mm 2 , 0.085mm 2 , 0.09mm 2 , 0.1mm 2 , 0.105mm 2 , 0.11mm 2 , 0.115mm 2 , 0.12mm 2 wait.

[0323] When S1≥0.008mm 2 When S1≤0.12mm, the risk of the first weak section cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell 20. 2 When the internal pressure of the battery cell 20 reaches the detonation pressure, the first weak section is more likely to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.12mm 2 When the battery cell 20 is opened, it can better resist external impact and is easy to open and release pressure when the internal pressure of the battery cell 20 reaches the detonation pressure.

[0324] In some embodiments, the second cross-sectional area is S2, which satisfies: 0.001 mm 2 ≤S2≤1mm 2 .

[0325] The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction can be: S2 = 0.001 mm 2 , 0.0015mm 2 , 0.002mm 2 , 0.003mm 2 , 0.005mm 2 , 0.01mm 2 , 0.03mm 2 , 0.05mm 2 , 0.08mm 2 , 0.1mm 2 , 0.15mm2 , 0.2mm 2 , 0.25mm 2 , 0.3mm 2 , 0.35mm 2 , 0.4mm 2 , 0.45mm 2 , 0.5mm 2 , 0.55mm 2 , 0.6mm 2 , 0.65mm 2 , 0.7mm 2 , 0.75mm 2 , 0.8mm 2 , 0.85mm 2 , 0.9mm 2 , 0.95mm 2 , 1mm 2 wait.

[0326] When S2≥0.001mm 2 When S2≤1mm, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is large, and it is not easy to crack when subjected to external impact, which is beneficial to improving the reliability of the battery cell 20. 2 When the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is not too large, it is beneficial to reduce the resistance of the predetermined pressure relief area 21431 to flip over, and facilitate the predetermined pressure relief area 21431 to flip open quickly. 2 ≤S2≤1mm 2 , which can take into account both resisting external impact and facilitating the rapid flipping and opening of the predetermined pressure relief area 21431.

[0327] In some embodiments, 0.008 mm 2 ≤S2≤0.45mm 2 .

[0328] The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction can be: S2 = 0.008 mm 2 , 0.009mm 2 , 0.01mm 2 , 0.03mm 2 , 0.05mm 2 , 0.08mm 2 , 0.1mm 2 , 0.13mm 2 , 0.15mm 2 , 0.18mm 2 , 0.2mm 2 , 0.22mm 2 , 0.25mm2 , 0.28mm 2 , 0.3mm 2 , 0.33mm 2 , 0.35mm 2 , 0.38mm 2 , 0.4mm 2 , 0.43mm 2 , 0.45mm 2 wait.

[0329] When S2≥0.008mm 2 When S2≤0.45mm, the risk of the second weak portion 2145 cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell 20. 2 , the resistance to the predetermined pressure relief area 21431 turning over is smaller, which facilitates the predetermined pressure relief area 21431 to turn over and open quickly. Therefore, when 0.008mm 2 ≤S2≤0.45mm 2 When the pressure relief area 21431 is opened, the pressure relief area 21431 can be better protected against external impacts and can be quickly flipped open.

[0330] Optionally, 0.03 mm 2 ≤S2≤0.15mm 2 .

[0331] The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction can be: S2 = 0.03 mm 2 , 0.035mm 2 , 0.04mm 2 , 0.045mm 2 , 0.05mm 2 , 0.055mm 2 , 0.06mm 2 , 0.065mm 2 , 0.07mm 2 , 0.075mm 2 , 0.08mm 2 , 0.085mm 2 , 0.09mm 2 , 0.095mm 2 , 0.1mm 2 , 0.105mm 2 , 0.11mm 2 , 0.115mm 2 , 0.12mm 2 , 0.125mm 2 , 0.13mm 2 , 0.135mm 2 , 0.14mm2 , 0.145mm 2 , 0.15mm 2 wait.

[0332] When S2≥0.03mm 2 When S2≤0.15mm, the risk of the second weak portion 2145 cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell 20. 2 , the resistance to the predetermined pressure relief area 21431 turning over is smaller, which facilitates the predetermined pressure relief area 21431 to turn over and open quickly. Therefore, when 0.03mm 2 ≤S2≤0.15mm 2 When the pressure relief component 214 is opened, it can better resist external impact and facilitate the rapid flipping and opening of the predetermined pressure relief area 21431. Referring to Figures 3, 4, 5, 6, and 7, in some embodiments, the pressure relief component 214 is provided with a second groove 21451. The pressure relief component 214 forms a second weak portion 2145 in the area provided with the second groove 21451. The second groove 21451 is provided on the surface of the pressure relief component 214 facing the interior of the housing 21.

[0333] Along the thickness direction of the first wall 211 , the pressure relief component 214 has a first surface 2111 and a second surface 2112 opposite to each other, wherein the first surface 2111 faces away from the interior of the housing 21 and the second surface 2112 faces the interior of the housing 21 . The second groove 21451 is provided on the second surface 2112 .

[0334] The second groove 21451 can be formed by various methods, such as stamping, cold heading, etc. For example, the second groove 21451 can be formed by stamping on the pressure relief component 214 along the direction from the second surface 2112 to the first surface 2111.

[0335] Stamping or cold heading the second groove 21451 causes the groove wall of the second groove 21451 to undergo cold work hardening (changing the grain arrangement, causing lattice distortion, reducing the metal's plasticity, and increasing the material's hardness). This enhances its ability to resist external impact and makes it less susceptible to damage from external impact. This helps reduce the risk of leakage from the pressure relief component 214.

[0336] Providing a second groove 21451 in the pressure relief component 214 forms the second weak portion 2145, which is simple, convenient, and low-cost. Furthermore, by providing the second groove 21451 on the surface of the pressure relief component 214 facing the interior of the housing 21, the predetermined pressure relief area 21431 needs to overcome less tension when flipping, thereby facilitating quick flipping and opening of the predetermined pressure relief area 21431, thereby improving the reliability of the battery cell 20.

[0337] 3, 4, 5, 6, and 7, in some embodiments, the pressure relief component 214 has a first surface 2111 and a second surface 2112 disposed opposite each other in the thickness direction of the first wall 211. The first surface 2111 is provided with a first groove 2146, and the pressure relief component 214 forms a first weakened portion 2144 in the region where the first groove 2146 is provided. The second surface 2112 is provided with a second groove 21451, and the pressure relief component 214 forms a second weakened portion 2145 in the region where the second groove 21451 is provided.

[0338] The first groove 2146 is provided on the first surface 2111 , and the second groove 21451 is provided on the second surface 2112 . The first groove 2146 and the second groove 21451 are respectively located on two surfaces of the pressure relief component 214 that are opposite to each other along the thickness direction of the first wall 211 .

[0339] Along the thickness direction of the first wall 211, the first weak portion 2144 is the portion of the pressure relief component 214 located between the bottom surface of the first groove 2146 farthest from the first surface 2111 and the second surface 2112. The second weak portion 2145 is the portion of the pressure relief component 214 located between the bottom surface of the second groove 21451 farthest from the second surface 2112 and the first surface 2111.

[0340] The first groove 2146 can be formed by various methods, such as stamping, cold heading, etc. For example, the first groove 2146 can be formed by stamping on the pressure relief component 214 along the direction from the first surface 2111 to the second surface 2112.

[0341] Stamping or cold heading the first groove 2146 causes the groove wall of the first groove 2146 to undergo cold work hardening (changing the grain arrangement, causing lattice distortion, reducing the metal's plasticity, and increasing the material's hardness). This enhances its ability to resist external impact and makes it less susceptible to damage from external impact. This helps reduce the risk of leakage from the pressure relief component 214.

[0342] The first and second weak portions 2144, 2145 are formed by providing the first and second grooves 2146, 21451 on the pressure relief component 214, which is simple, convenient, and low-cost. By providing the first and second grooves 2146, 21451 on the first and second surfaces 2111, 2112 of the pressure relief component 214, respectively, so that the first and second grooves 2146, 21451 are located on opposite sides of the pressure relief component 214, it is convenient to machine the first and second grooves 2146, 21451 on opposite sides of the pressure relief component 214, thereby reducing the mutual influence between the first and second grooves 2146, 21451 during the machining process.

[0343] Optionally, the first surface 2111 is a surface of the pressure relief component 214 facing away from the interior of the housing 21 , and the second surface 2112 is a surface of the pressure relief component 214 facing the interior of the housing 21 .

[0344] The first surface 2111 is the surface of the pressure relief component 214 facing away from the interior of the housing 21, that is, the outer surface of the pressure relief component 214, that is, the aforementioned third outer surface 2113. The second surface 2112 is the surface of the pressure relief component 214 facing the interior of the housing 21, that is, the inner surface of the pressure relief component 214.

[0345] The first groove 2146 is disposed on the outer surface of the pressure relief component 214 , and the second groove 21451 is disposed on the inner surface of the pressure relief component 214 .

[0346] By positioning the first groove 2146 on the surface of the pressure relief component 214 facing away from the interior of the housing 21, the first weak portion 2144 is less prone to cracking due to the tension it must overcome. By positioning the second groove 21451 on the surface of the pressure relief component 214 facing the interior of the housing 21, the predetermined pressure relief area 21431 is less prone to overturning due to the tension it must overcome. This facilitates quick opening of the predetermined pressure relief area 21431, thereby improving the reliability of the battery cell 20.

[0347] Please refer to Figure 9, which is a bottom view of the housing 21 of a battery cell 20 provided in some further embodiments of the present application. In some further embodiments, the pressure relief component 214 is provided with a first groove 2146, and the pressure relief component 214 forms a first weakened portion 2144 in the region where the first groove 2146 is provided. The first groove 2146 includes a first groove section 2143a and a second groove section 2143b, which are connected to each other. The pressure relief component 214 forms a weakened section in each region where the first groove section 2143a and the second groove section 2143b are provided. The two weakened sections together define a predetermined pressure relief area 21431.

[0348] The line connecting the free end of the first slot section 2143a and the free end of the second slot section 2143b is a first line. The closed area enclosed by the weak section corresponding to the first slot section 2143a, the weak section corresponding to the second slot section 2143b, and the first line is a predetermined pressure relief area 21431.

[0349] A weak section is formed at the bottom of each of the first and second groove sections 2143a, 2143b, and the two weak sections together define a predetermined pressure relief area 21431. The first and second groove sections 2143a, 2143b are arranged along the edge of the predetermined pressure relief area 21431, so that when the battery cell 20 releases pressure, the two weak sections can break along the edge of the predetermined pressure relief area 21431.

[0350] For example, in FIG9 , one end of the first slot segment 2143a is connected to one end of the second slot segment 2143b, so that the first slot segment 2143a and the second slot segment 2143b form an L-shaped first groove 2146. Referring to FIG9 , a first connecting line connects the two ends of the L-shaped structure. Of course, in other embodiments, one end of the second slot segment 2143b can also be connected to the middle of the first slot segment 2143a, so that the pressure relief component 214 forms a predetermined pressure relief area 21431 on both sides of the second slot segment 2143b.

[0351] The first groove section 2143a and the second groove section 2143b are interconnected structures, so that the first groove section 2143a and the second groove section 2143b jointly define a predetermined pressure relief area 21431. On the one hand, it can increase the pressure relief area of ​​the battery cell 20 to increase the pressure relief rate of the battery cell 20. On the other hand, it makes the position where the first groove section 2143a and the second groove section 2143b are interconnected weaker, which is easier to crack and open the predetermined pressure relief area 21431 to release the internal pressure of the battery cell 20.

[0352] Referring to Figures 3, 4, 5, 6, and 7, in some embodiments, the pressure relief component 214 is provided with a first groove 2146. A first weakened portion 2144 is formed in the region where the first groove 2146 is provided. The first groove 2146 includes a first groove section 2143a, a second groove section 2143b, and a third groove section 2143c. The first groove section 2143a and the third groove section 2143c are disposed opposite each other, and the second groove section 2143b connects the first groove section 2143a and the third groove section 2143c. The pressure relief component 214 forms a weakened section in each region where the first groove section 2143a, the second groove section 2143b, and the third groove section 2143c are disposed. Together, these three weakened sections define a predetermined pressure relief area 21431.

[0353] The first slot section 2143a and the third slot section 2143c are spaced apart and at least partially opposite to each other. Optionally, the first slot section 2143a and the third slot section 2143c both extend along the first direction.

[0354] The second slot segment 2143b connects the first slot segment 2143a and the third slot segment 2143c, that is, the second slot segment 2143b is located between the first slot segment 2143a and the third slot segment 2143c, and the two ends of the second slot segment 2143b are respectively connected to the first slot segment 2143a and the third slot segment 2143c. Of course, in other embodiments, the two ends of the second slot segment 2143b can extend out of the first slot segment 2143a and the third slot segment 2143c, respectively.

[0355] The first, second, and third slot sections 2143a, 2143b, and 2143c each have a weak section at their bottoms. These three weak sections collectively define a predetermined pressure relief area 21431. Referring to Figure 5, a line connecting the free ends of the first slot section 2143a and the free ends of the second slot section 2143b is a first line. The first line is positioned opposite the second slot section 2143b along a first direction. The enclosed area formed by the weak section corresponding to the first slot section 2143a, the weak section corresponding to the second slot section 2143b, the weak section corresponding to the third slot section 2143c, and the first line constitutes the predetermined pressure relief area 21431. That is to say, the first groove section 2143a, the second groove section 2143b and the third groove section 2143c are structures arranged along the edge of the predetermined pressure relief area 21431, so that the predetermined pressure relief area 21431 can be opened with the first groove section 2143a, the second groove section 2143b and the third groove section 2143c as boundaries, that is, the predetermined pressure relief area 21431 is formed in the area enclosed by the first groove section 2143a, the second groove section 2143b and the third groove section 2143c, so that the part of the pressure relief component 214 located in the predetermined pressure relief area 21431 can be opened with the first groove section 2143a, the second groove section 2143b and the third groove section 2143c as boundaries when the battery cell 20 is depressurized, thereby releasing the internal pressure of the battery cell 20.

[0356] Referring to Figure 10 , which is a bottom view of the housing 21 of a battery cell 20 provided in other embodiments of the present application, the first groove 2146 formed by the first, second, and third groove segments 2143a, 2143b, and 2143c can be U-shaped, with one end of the second groove segment 2143b connected to one end of the first groove segment 2143a and the other end connected to one end of the third groove segment 2143c, thereby forming a predetermined pressure relief area 21431 on the pressure relief component 214. In this case, the first connecting line closes the open end of the U-shaped structure.

[0357] The first groove 2146 includes a first groove section 2143a, a second groove section 2143b and a third groove section 2143c. The second groove section 2143b connects the first groove section 2143a and the third groove section 2143c, so that the pressure relief component 214 can split along the first groove section 2143a, the second groove section 2143b and the third groove section 2143c when the battery cell 20 releases pressure, so as to open the predetermined pressure relief area 21431 to release the internal pressure of the battery cell 20. The first groove 2146 with this structure makes the connection position between the first groove section 2143a and the second groove section 2143b and the connection position between the first groove section 2143a and the third groove section 2143c weaker, easier to split and open the predetermined pressure relief area 21431 for pressure relief, and can further improve the pressure relief area and pressure relief rate of the battery cell 20.

[0358] 3, 4, 5, 6, and 7, in some embodiments, the first weakened portion 2144 defines two predetermined pressure relief areas 21431, which are located on either side of the second groove section 2143b. Each predetermined pressure relief area 21431 is provided with at least one second weakened portion 2145.

[0359] 5 , the first groove 2146 formed by the first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c may be in an “H”-shaped structure to form two predetermined pressure relief areas 21431 on the pressure relief component 214, and the two predetermined pressure relief areas 21431 are respectively located on both sides of the first groove segment 2143a.

[0360] Each predetermined pressure relief area 21431 may be provided with one second weak portion 2145 , two second weak portions 2145 , three second weak portions 2145 or more than three second weak portions 2145 . As shown in FIG. 5 , each predetermined pressure relief area 21431 is provided with one second weak portion 2145 .

[0361] The first weak portion 2144 defines two predetermined pressure relief areas 21431, and each predetermined pressure relief area 21431 is correspondingly provided with at least one second weak portion 2145. When the battery cell 20 releases pressure, the two predetermined pressure relief areas 21431 are flipped open under the guidance of their corresponding second weak portions 2145, so that the battery cell 20 has a larger pressure relief area, which is beneficial to improving the pressure relief rate of the battery cell 20 and improving the reliability of the battery cell 20.

[0362] 3 , 4 , 5 , 6 , and 7 , in some embodiments, each predetermined pressure relief area 21431 is provided with a corresponding second weak portion 2145 , and the pressure relief component 214 is provided with a second groove 21451 . The pressure relief component 214 forms a second weak portion 2145 in the area provided with the second groove 21451 . The first groove 2146 is located between the two second grooves 21451 .

[0363] The pressure relief component 214 forms a second weak portion 2145 in the area where the second grooves 21451 are provided, and each predetermined pressure relief area 21431 is correspondingly provided with a second groove 21451. Along the first direction, the two second grooves 21451 are located on both sides of the second slot section 2143b.

[0364] 5 , along the first direction, the first groove 2146 is located between the two second grooves 21451 , that is, along the first direction, the first groove section 2143 a , the second groove section 2143 b and the third groove section 2143 c are all located between the two second grooves 21451 .

[0365] The predetermined pressure relief areas 21431 correspond one-to-one with the second weak portions 2145, which can reduce the number of second weak portions 2145 required, reduce the number of times the pressure relief component 214 needs to be processed, and reduce the stress on the pressure relief component 214. The first groove 2146 is positioned between the two second grooves 21451. When the battery cell 20 releases pressure, the pressure relief component 214 can split along the first groove section 2143a, the second groove section 2143b, and the third groove section 2143c, thereby opening the two predetermined pressure relief areas 21431. The two predetermined pressure relief areas 21431 are then flipped open under the guidance of their corresponding second weak portions 2145, resulting in a larger pressure relief area for the battery cell 20, which is beneficial for increasing the pressure relief rate and reliability of the battery cell 20.

[0366] Please refer to Figures 3, 4, 5, 6 and 7. In some embodiments, the position where the second slot segment 2143b is connected to the first slot segment 2143a deviates from the two ends of the first slot segment 2143a, and the position where the second slot segment 2143b is connected to the third slot segment 2143c deviates from the two ends of the third slot segment 2143c.

[0367] Among them, the connection position of the second groove segment 2143b and the first groove segment 2143a deviates from the two ends of the first groove segment 2143a, that is, the second groove segment 2143b is connected between the two ends of the first groove segment 2143a. Similarly, the connection position of the third groove segment 2143c and the second groove segment 2143b deviates from the two ends of the third groove segment 2143c, that is, the second groove segment 2143b is connected between the two ends of the third groove segment 2143c, so that the shape of the first groove 2146 formed by the first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c is an approximately "H"-shaped structure.

[0368] By setting the connection position of the second groove section 2143b and the first groove section 2143a to be located between the two ends of the second groove section 2143b, and setting the connection position of the second groove section 2143b and the third groove section 2143c to be located between the two ends of the third groove section 2143c, so that the first groove section 2143a, the second groove section 2143b and the third groove section 2143c form a structure similar to an "H" shape, so that predetermined pressure relief areas 21431 can be formed on both sides of the second groove section 2143b of the first groove 2146, and the two predetermined pressure relief areas 21431 can be opened in a split manner to relieve pressure when the battery cell 20 is relieved of pressure, which is beneficial to further increase the pressure relief effect of the battery cell 20 and can effectively improve the pressure relief rate of the battery cell 20.

[0369] In some embodiments, referring to FIG5 , the first slot segment 2143a, the second slot segment 2143b, and the third slot segment 2143c all extend along straight lines, and the first slot segment 2143a and the third slot segment 2143c are both perpendicular to the second slot segment 2143b. In other words, the extension direction of the second slot segment 2143b is perpendicular to the extension directions of the first slot segment 2143a and the third slot segment 2143c, so that the first groove 2146 formed by the first slot segment 2143a, the second slot segment 2143b, and the third slot segment 2143c is in an "H" shape. Two predetermined pressure relief areas 21431 are formed on either side of the second slot segment 2143b. The areas of the two predetermined pressure relief areas 21431 may be the same or different.

[0370] By setting the first groove section 2143a and the third groove section 2143c to be perpendicular to the second groove section 2143b, the extension direction of the second groove section 2143b is made the arrangement direction of the first groove section 2143a and the third groove section 2143c. On the one hand, the regularity of the shape of the first groove 2146 can be improved, which is conducive to reducing the processing difficulty of the first groove 2146, thereby reducing the manufacturing cost of the battery cell 20. On the other hand, it is convenient for the two predetermined pressure relief areas 21431 on the pressure relief component 214 located on both sides of the second groove section 2143b to relieve pressure in opposite directions when the battery cell 20 is relieved.

[0371] According to some embodiments of the present application, referring to Figure 11, which is a bottom view of the housing 21 of the battery cell 20 provided in some other embodiments of the present application, the first groove section 2143a, the second groove section 2143b, and the third groove section 2143c all extend along an arc trajectory.

[0372] For example, in FIG11 , the two ends of the second groove segment 2143b are connected to one end of the first groove segment 2143a and one end of the third groove segment 2143c, respectively. Furthermore, the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c all extend along an arcuate trajectory, so that the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c form a first groove 2146 having a C-shaped structure. In this case, the first connecting line closes the open end of the C-shape.

[0373] By setting the first groove section 2143a, the second groove section 2143b and the third groove section 2143c as structures extending along an arc trajectory, it is beneficial to improve the arc degree of the connection position of the first groove section 2143a and the second groove section 2143b, and the arc degree of the connection position of the second groove section 2143b and the third groove section 2143c. On the one hand, it can reduce the difficulty of processing the first groove 2146. On the other hand, it can facilitate the pressure relief component 214 to open the predetermined pressure relief area 21431 after it is split along the first groove section 2143a, the second groove section 2143b and the third groove section 2143c to release the internal pressure of the battery cell 20.

[0374] 3, 4, 5, 6, and 7, in some embodiments, the pressure relief component 214 is provided with a second groove 21451. The pressure relief component 214 forms a second weak portion 2145 in the region where the second groove 21451 is provided. The first groove section 2143a, the second groove section 2143b, and the third groove section 2143c are all spaced apart from the second groove 21451.

[0375] The first slot segment 2143 a , the second slot segment 2143 b and the third slot segment 2143 c are all spaced apart from the second groove 21451 , and the first slot segment 2143 a , the second slot segment 2143 b and the third slot segment 2143 c are not in contact with the second groove 21451 .

[0376] By arranging the first groove section 2143a, the second groove section 2143b and the third groove section 2143c to be spaced apart from the second groove 21451, on the one hand, the mutual influence between the first groove 2146 and the second groove 21451 during the processing can be reduced; on the other hand, the phenomenon that the pressure relief component 214 cracks along the second groove 21451 when the pressure relief component 214 cracks along the first groove 2146 to relieve pressure can be reduced, and the stress influence between the area where the first groove 2146 of the pressure relief component 214 is set and the area where the second groove 21451 of the pressure relief component 214 is set can be reduced.

[0377] In some embodiments, the second slot segment 2143 b and the second groove 21451 are arranged opposite to each other along the first direction. Along the first direction, the first slot segment 2143 a and the third slot segment 2143 c are spaced apart from the second groove 21451 .

[0378] Along the first direction, the second slot segment 2143b is disposed opposite the second groove 21451, and the first slot segment 2143a and the third slot segment 2143c are both spaced apart from the second groove 21451. A distance exists between the first slot segment 2143a and the second groove 21451 in the direction in which the second slot segment 2143b and the second groove 21451 are disposed opposite each other. A distance exists between the third slot segment 2143c and the second groove 21451 in the direction in which the second slot segment 2143b and the second groove 21451 are disposed opposite each other.

[0379] By arranging the second groove section 2143b and the second groove 21451 relative to each other along the first direction, the first groove section 2143a and the third groove section 2143c are spaced apart from the second groove 21451 in the first direction, so that the predetermined pressure relief area 21431 defined by the first groove section 2143a, the second groove section 2143b and the third groove section 2143c can be flipped around the area of ​​the pressure relief component 214 where the second groove 21451 is provided when it is opened, and the flipping angle of the predetermined pressure relief area 21431 after being opened can be increased, so as to increase the pressure relief area of ​​the battery cell 20.

[0380] 3, 4, 5, 6 and 7, in some embodiments, the first wall 211 has a third outer surface 2113 facing away from the interior of the housing 21. The third outer surface 2113 is rectangular. The first direction is parallel to the length or width of the rectangle.

[0381] The second groove section 2143b and the second groove 21451 are arranged along the length or width of the third outer surface 2113. The first groove section 2143a and the third groove section 2143c are spaced apart from the second groove 21451 along the length or width of the third outer surface 2113. The large space along the length or width of the third outer surface 2113 facilitates the processing of the first groove 2146 and the second groove 21451. Furthermore, during production, the detonation pressure of the multiple battery cells 20 processed is relatively consistent.

[0382] Referring to Figures 3, 4, 5, 6, and 7, in some embodiments, the pressure relief component 214 has a first surface 2111 and a second surface 2112 disposed opposite each other in the thickness direction of the first wall 211. The pressure relief component 214 is provided with first grooves 2146. The first grooves 2146 are arranged in a multi-stage pattern from the first surface 2111 to the second surface 2112. In two adjacent stages of grooves, the first stage groove farther from the first surface 2111 is disposed on the bottom surface of the first stage groove closer to the first surface 2111. The bottom wall of the first stage groove furthest from the first surface 2111 in the multi-stage grooves serves as the first weak portion 2144.

[0383] The pressure relief component 214 is provided with a plurality of grooves, which are arranged in sequence along the direction from the first surface 2111 to the second surface 2112. The bottom surface profile of each groove gradually decreases. The cross-sectional shape of the grooves can be various, such as rectangular or circular. The grooves on the pressure relief component 214 can be formed by various methods, such as stamping, cold heading, etc.

[0384] The bottom wall of the first-level groove farthest from the first surface 2111 in the multi-level groove is the first weak portion 2144, that is, the portion of the pressure relief component 214 located between the bottom surface of the first groove 2146 farthest from the first surface 2111 and the second surface 2112 is the first weak portion 2144.

[0385] For example, as shown in Figures 6 and 7, the pressure relief component 214 is provided with three levels of grooves, namely, a first-level groove 2141, a second-level groove 2142, and a third-level groove 2143. During processing and forming, the first-level groove 2141 can be first stamped on the first surface 2111, the second-level groove 2142 can be stamped on the bottom surface of the first-level groove 2141, and finally, the third-level groove 2143 can be stamped on the bottom surface of the second-level groove 2142. In this case, the bottom wall of the third-level groove 2143 constitutes the first weak portion 2144, that is, the portion of the pressure relief component 214 located between the bottom surface of the third-level groove 2143 and the second surface 2112 constitutes the first weak portion 2144.

[0386] As shown in FIG5 , FIG6 and FIG7 , the third-stage groove 2143 includes the first groove section 2143 a , the second groove section 2143 b and the third groove section 2143 c mentioned above.

[0387] The multi-level grooves are sequentially arranged on the pressure relief component 214 along the direction from the first surface 2111 to the second surface 2112 . During molding, the multi-level grooves can be sequentially molded on the pressure relief component 214 along the direction from the first surface 2111 to the second surface 2112 .

[0388] The multi-level grooves are sequentially arranged on the pressure relief component 214 in the direction from the first surface 2111 to the second surface 2112. During molding, the multi-level grooves can be formed step by step, thereby reducing the molding force on the pressure relief component 214 and reducing the risk of cracks in the pressure relief component 214. The pressure relief component 214 is not likely to fail due to cracks in the locations where the grooves are set, thereby improving the reliability of the battery cell 20. When forming the multi-level grooves, stamping or cold heading can be used. In this way, the groove walls will undergo cold work hardening (the grain arrangement changes, resulting in lattice distortion, reducing the plasticity of the metal and increasing the hardness of the material), and its ability to resist external impact is enhanced, making it less susceptible to damage due to external impact. This helps to reduce the risk of leakage in the pressure relief component 214.

[0389] In some embodiments, along the thickness direction of the first wall, the maximum groove depth of the first groove 2146 is F, the thickness of the pressure relief component 214 is N, and 0.16≤F / N<1.

[0390] The maximum distance between the opening of the first groove 2146 and the bottom surface of the first groove along the thickness direction of the first wall 211 is the maximum groove depth of the first groove 2146 .

[0391] F / N can be any point value among 0.16, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 0.99, etc., or a range between any two of them.

[0392] It is understandable that if the pressure relief component 214 and the first wall 211 are integrally formed, the first wall 211 can serve as the pressure relief component 214 , and the thickness of the pressure relief component 214 is the same as the thickness of the first wall 211 .

[0393] In this embodiment, 0.16≤F / N<1, so that the maximum depth of the first groove 2146 accounts for a small proportion of the thickness of the pressure relief component 214, and the bursting pressure of the battery cell 20 is not too high, which is conducive to improving the timeliness of the pressure relief of the battery cell 20.

[0394] In some embodiments, 0.4 mm ≤ F ≤ 2 mm, and 0.8 mm ≤ N ≤ 2.5 mm.

[0395] F can be any point value among 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, 1.8mm, 1.85mm, 1.9mm, 1.95mm, 2mm, etc., or any range value between any two of them.

[0396] N can be any point value among 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, 1.8mm, 1.85mm, 1.9mm, 1.95mm, 2mm, 2.05mm, 2.1mm, 2.15mm, 2.2mm, 2.25mm, 2.3mm, 2.35mm, 2.4mm, 2.45mm, 2.5mm, etc., or a range value between any two of them.

[0397] In this embodiment, 0.4 mm ≤ F ≤ 2 mm, and 0.8 mm ≤ N ≤ 2.5 mm, keeping the maximum depth of the first groove 2146 and the thickness of the pressure relief component 214 within a reasonable range, resulting in better economic efficiency. In embodiments where the first wall 211 serves as the pressure relief component 214, the thickness of the first wall 211 is 0.8 mm to 2.5 mm. A thickness of 0.8 mm or greater ensures sufficient strength for the first wall 211. A thickness of 2 mm or less ensures that the first wall 211 is not excessively thick. Given a given volume of the housing 21, the internal space of the housing 21 can be increased to create more space for the electrode assembly 22. While maintaining the thickness of the first wall 211 within the range of 0.8 mm to 2.5 mm, the maximum depth of the first groove 2146 is controlled within the range of 0.4 mm to 2 mm, ensuring a better match between the maximum depth of the first groove 2146 and the thickness of the pressure relief component 214, thereby ensuring that the pressure relief component 214 has good pressure relief capabilities.

[0398] In some embodiments, the pressure relief component 214 is integrally formed with the first wall 211 .

[0399] Integrally formed means that the first wall 211 and the pressure relief component 214 are an integral structure when provided. For example, the pressure relief component 214 can be formed on the first wall 211 by stamping or cold heading.

[0400] Integrating the pressure relief component 214 with the first wall 211 eliminates the need for additional welding or bonding processes, which helps reduce the risk of leakage from the pressure relief component 214. Furthermore, during production, the detonation pressures of the multiple battery cells 20 produced can be made more consistent.

[0401] According to some embodiments of the present application, the material of the first wall 211 includes steel.

[0402] Exemplarily, the material of the first wall 211 may be carbon steel, alloy steel, stainless steel, or the like.

[0403] It should be noted that the material of the first wall 211 includes steel. If the first wall 211 is the end cover 216 of the outer shell 21, the material of the end cover 216 is steel; if the first wall 211 is a wall in the shell 215, the material of the shell 215 is steel.

[0404] In this embodiment, by setting the material of the first wall 211 to steel, due to the high strength of steel, the first wall 211 made of steel has better strength, so that when the bursting pressure of the battery cell 20 is constant, the first wall 211 can be made thinner, which is beneficial to saving the space occupied by the first wall 211.

[0405] In some embodiments, the steel material is carbon steel or stainless steel.

[0406] Illustratively, the carbon steel may be low carbon steel, medium carbon steel, or high carbon steel.

[0407] In this embodiment, carbon steel or stainless steel is used as the material of the first wall 211 , which is low in cost and easy to manufacture.

[0408] In some embodiments, the pressure relief component 214 is made of aluminum alloy.

[0409] It is understood that in embodiments where the pressure relief component 214 is integrally formed with the first wall 211, the material of the first wall 211 includes an aluminum alloy. If the first wall 211 is an end cap 216, the end cap 216 may be made of an aluminum alloy; if the first wall 211 is a wall portion within the housing 215, the housing 215 may also be made of an aluminum alloy.

[0410] Aluminum alloy is lightweight and ductile, making it easier to form the first groove 2146 and the second groove 21451 on the pressure relief component 214. In the embodiment where the pressure relief component 214 and the first wall 211 are integrally formed, the first wall 211 is made of aluminum alloy, which can effectively reduce the difficulty of forming the first wall 211.

[0411] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other individual elements ≤ 0.03%.

[0412] This aluminum alloy belongs to the third series aluminum, has lower hardness and better forming ability, reduces the difficulty of processing the first groove 2146 and the second groove 21451, is conducive to improving the processing accuracy of the first groove 2146 and the second groove 21451, and improves the pressure relief consistency of the pressure relief component 214.

[0413] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 96.7%, 0.05% ≤ copper ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other individual element components ≤ 0.05%, and the total composition of other elements ≤ 0.15%.

[0414] This aluminum alloy belongs to the fifth series aluminum. The pressure relief component 214 made of this aluminum alloy has higher hardness, greater strength and good anti-destruction ability.

[0415] In other embodiments, the pressure relief component 214 is provided separately from the first wall 211 , the first wall 211 is provided with a pressure relief hole, and the pressure relief component 214 is installed on the first wall 211 and covers the pressure relief hole.

[0416] The phrase "pressure relief component 214 is provided separately from first wall 211, with a pressure relief hole provided in first wall 211, and pressure relief component 214 is mounted on first wall 211 and covers the pressure relief hole" means that during manufacturing, a pressure relief hole is provided in first wall 211, and pressure relief component 214 and first wall 211 are provided separately and ultimately connected together. For example, pressure relief component 214 can be welded to first wall 211. Pressure relief component 214 can be a bursting disk mounted on first wall 211.

[0417] The pressure relief component 214 is provided separately from the first wall 211 and is installed on the first wall 211 , thereby facilitating processing and manufacturing.

[0418] 3, 4, 5, 6 and 7, in some embodiments, the battery cell 20 includes an electrode assembly 22, which is accommodated in a housing 21. The first wall 211 supports the electrode assembly 22 along the direction of gravity.

[0419] The first wall 211 is a wall on the outer shell 21 that supports the electrode assembly 22 along the direction of gravity. It is understood that the first wall 211 can be the bottom wall of the housing 215. The first wall 211 can also be an end cap 216. When the first wall 211 is an end cap 216, the battery cell 20 is used in an inverted position.

[0420] The first wall 211 supports the electrode assembly 22 along the direction of gravity, and the pressure relief component 214 is set on the first wall 211. In this way, when the battery cell 20 is depressurized, the ejected fluid medium is not easy to act on other electrical connection components, reducing the risk of short circuit when the battery cell 20 is depressurized.

[0421] 3 , 4 , 5 , 6 and 7 , in some embodiments, the battery cell 20 includes an electrode terminal 23 , and the electrode terminal 23 is disposed on other walls of the housing 21 except the first wall 211 .

[0422] The electrode terminal 23 and the pressure relief member 214 are disposed on different walls of the housing 21. For example, when the first wall 211 is the bottom wall of the housing 215, the electrode terminal 23 can be disposed on a side wall of the housing 215 or on the end cap 216. For another example, when the first wall 211 is one side wall of the housing 215, the electrode terminal 23 can be disposed on another side wall, the bottom wall, or the end cap 216 of the housing 215. When the first wall 211 is the end cap 216, the electrode terminal 23 can be disposed on a side wall or the bottom wall of the housing 215.

[0423] The electrode terminal 23 and the pressure relief component 214 are respectively arranged on different walls of the shell 21. When the battery cell 20 is depressurized, the ejected fluid medium is not likely to act on the electrode terminal 23 and cause the electrode terminal 23 to short-circuit, thereby reducing the risk of short circuit when the battery cell 20 is depressurized.

[0424] Optionally, the electrode terminal 23 is provided on a wall of the housing 21 opposite to the first wall 211 .

[0425] When the first wall 211 is the bottom wall of the housing 215, the electrode terminal 23 can be disposed on the end cap 216. When the first wall 211 is a side wall of the housing 215, the electrode terminal 23 can be disposed on the other side wall of the housing 215 opposite the first wall 211. When the first wall 211 is the end cap 216, the electrode terminal 23 can be disposed on the bottom wall of the housing 215.

[0426] The electrode terminal 23 is arranged on the wall of the shell 21 opposite to the first wall 211. The electrode terminal 23 is far away from the pressure relief component 214. When the battery cell 20 is depressurized, the ejected fluid medium is less likely to act on the electrode terminal 23 and cause the electrode terminal 23 to short-circuit, further reducing the risk of short circuit when the battery cell 20 is depressurized.

[0427] 3 , 4 , 5 , 6 , and 7 , in some embodiments, the housing 21 includes a shell 215 and an end cap 216 . The shell 215 has an opening 2151 . The end cap 216 is connected to the shell 215 and closes the opening 2151 . The end cap 216 is a first wall 211 , or the shell 215 includes the first wall 211 .

[0428] The shell 215 includes an integrally formed side wall and bottom wall, that is, the shell 215 is manufactured using an integral molding process, such as an integral molding process such as stamping, casting or extrusion molding. In other words, the side wall and bottom wall of the shell 215 are an integral structure.

[0429] The housing 215 includes a first wall 211. That is, the first wall 211 is a wall of the housing 215. For example, in Figures 5 and 6, the first wall 211 is a bottom wall of the housing 215 that is disposed opposite the end cap 216 in the thickness direction of the first wall 211. Of course, in other embodiments, the first wall 211 may also be a side wall of the housing 215.

[0430] It should be noted that the structure of the battery cell 20 is not limited to this. In some embodiments, the battery cell 20 may also have other structures. For example, the outer shell 21 may include a shell 215 and an end cover 216. The interior of the shell 215 forms a accommodating cavity with an opening 2151, which is used to accommodate the electrode assembly 22. The end cover 216 closes the opening 2151, and the end cover 216 is the first wall 211.

[0431] It should be noted that the structure of the battery cell 20 can be various. In some embodiments, the outer shell 21 may include a shell 215 and two end covers 216. A accommodating cavity is formed inside the shell 215, and the accommodating cavity is used to accommodate the electrode assembly 22. The shell 215 is formed with openings 2151 at both ends in the thickness direction of the first wall 211, and the two openings 2151 are connected to the accommodating cavity. The two end covers 216 respectively close the two openings 2151, and one of the two end covers 216 is the first wall 211.

[0432] The shell 215 of the outer shell 21 is provided with openings 2151 at both ends in the thickness direction of the first wall 211, and the two end covers 216 respectively close the two openings 2151. The first wall 211 is one of the two end covers 216. The battery cell 20 adopting this structure is convenient for assembling the battery cell 20 from both ends of the shell 215, which is beneficial to reducing the manufacturing difficulty and assembly difficulty of the battery cell 20.

[0433] When the end cap 216 is the first wall 211, the pressure relief component 214 is disposed on the end cap 216, which simplifies and facilitates manufacturing. When the housing 215 includes the first wall 211, the pressure relief component 214 is disposed on a wall of the housing 215. The fluid medium ejected by the pressure relief component 214 is less likely to act on other electrical connection structures on the end cap 216, thereby reducing the risk of short circuits in the battery cells 20.

[0434] The embodiment of the present application further provides a battery 100 , which includes the above-mentioned battery cell 20 .

[0435] An embodiment of the present application further provides an electrical device, which includes the above-mentioned battery cell 20.

[0436] According to some embodiments of the present application, please refer to Figures 3 to 7.

[0437] An embodiment of the present application provides a battery cell 20, comprising a housing 21 and a pressure relief component 214. The housing 21 has a first wall 211, and the pressure relief component 214 is disposed on the first wall 211. The pressure relief component 214 includes a first weakened portion 2144, which defines a predetermined pressure relief area 21431. The pressure relief component 214 is configured to rupture along at least a portion of the first weakened portion 2144 when the battery cell 20 releases pressure. The pressure relief component 214 also includes a second weakened portion 2145, which is configured to guide at least a portion of the predetermined pressure relief area 21431 to flip, thereby opening at least a portion of the predetermined pressure relief area 21431. The battery cell 20 is provided with the first weakened portion 2144 and the second weakened portion 2145. When the battery cell 20 releases pressure, the first weakened portion 2144 ruptures, allowing the fluid medium within the battery cell 20 to flow out and release the pressure. By providing the second weak portion 2145, the strength of the pressure relief component 214 at the second weak portion 2145 is weakened, making it easier for the predetermined pressure relief area 21431 to flip open under the action of the fluid medium. This not only increases the probability of the predetermined pressure relief area 21431 opening, but also increases the opening speed of the predetermined pressure relief area 21431, thereby achieving rapid pressure relief and reducing the risk of explosion or fire of the battery cell 20, which is beneficial to improving the reliability of the battery cell 20.

[0438] Along the first direction, the distance between the first outer surface 2121 and the second outer surface 2131 is L, the minimum distance between the first weak portion 2144 and the first outer surface 2121 is L1, and the minimum distance between the first weak portion 2144 and the second outer surface 2131 is L2, satisfying the following: 0≤|L1-L2| / L≤0.1. When 0≤|L1-L2| / L≤0.1, the first weak portion 2144 is located near the middle of the first wall 211 along the first direction. The rigidity of the middle of the first wall 211 along the first direction is relatively low. When the battery cell 20 releases pressure, the middle of the first wall 211 along the first direction will experience significant deformation. This facilitates the first weak portion 2144 to rupture before the second weak portion 2145, allowing the predetermined pressure relief area 21431 to flip open under the guidance of the second weak portion 2145, thereby improving the reliability of the battery cell 20.

[0439] Along the first direction, a second weak portion 2145 is provided between the first weak portion 2144 and the first outer surface 2121; along the first direction, the distance between the first outer surface 2121 and the second outer surface 2131 is L, the minimum distance between the second weak portion 2145 and the first outer surface 2121 is L3, and the minimum distance between the second weak portion 2145 and the second outer surface 2131 is L4. The first weak portion 2144 includes at least one weak segment, and the cross-sectional area of ​​the weak segment perpendicular to its extension direction is S1. The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is S2, satisfying: |L4-L3| / L≥0.4, 0.7<S2 / S1≤1.5. When |L4 - L3| / L ≥ 0.4, the second weak portion 2145 deviates significantly from the middle position of the first wall 211 along the first direction. In this case, the second weak portion 2145 is close to the first outer surface 2121. The stiffness of the first wall 211 at the second weak portion 2145 differs significantly from the stiffness of the first wall 211 at the first weak portion 2144. Therefore, the stiffness has a significant impact on the cracking of the first and second weak portions 2144, 2145. If the effect of stiffness on the first and second weak portions 2144, 2145 is not considered, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction only needs to be greater than the cross-sectional area of ​​the weak section perpendicular to its extension direction, that is, S2 / S1>1. This allows the first weak portion 2144 to open and release pressure before the second weak portion 2145, and the second weak portion 2145 serves to guide the predetermined pressure relief zone 21431. However, considering that stiffness has a significant impact on the rupture of the first weak portion 2144 and the second weak portion 2145 (given the same cross-sectional area, the second weak portion 2145 is more difficult to rupture than the first weak portion 2144, and therefore, the cross-sectional area of ​​the second weak portion 2145 can be set to be smaller), when 0.7 < S2 / S1 ≤ 1, the first weak portion 2144 can also be opened to release pressure before the second weak portion 2145, and the second weak portion 2145 serves to guide the predetermined pressure relief area 21431. Similarly, because stiffness has a significant impact on the rupture of the first weak portion 2144 and the second weak portion 2145, when S2 / S1 ≤ 1.5, the strength of the pressure relief component 214 at the second weak portion 2145 is relatively low, thereby minimizing the obstruction to the flipping and opening of the predetermined pressure relief area 21431, making it easier for the predetermined pressure relief area 21431 to flip and open under the action of the fluid medium.

[0440] Along the first direction, a second weak portion 2145 is provided between the first weak portion 2144 and the first outer surface 2121; along the first direction, the distance between the first outer surface 2121 and the second outer surface 2131 is L, the minimum distance between the second weak portion 2145 and the first outer surface 2121 is L3, and the minimum distance between the second weak portion 2145 and the second outer surface 2131 is L4. The first weak portion 2144 includes at least one weak segment, and the cross-sectional area of ​​the weak segment perpendicular to its extension direction is S1. The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is S2, satisfying: |L4-L3| / L<0.4, 1.5<S2 / S1≤5. When |L4-L3| / L<0.4, the second weak portion 2145 deviates less from the middle position of the first wall 211 along the first direction. At this point, the second weak portion 2145 is also closer to the middle position of the first wall 211 along the first direction. The stiffness of the first wall 211 at the second weak portion 2145 is slightly different from the stiffness of the first wall 211 at the first weak portion 2144. Therefore, the stiffness has a smaller impact on the cracking of the first and second weak portions 2144, 2145. When S2 / S1>1.5, the first weak portion 2144 can open and release pressure before the second weak portion 2145. The second weak portion 2145 guides the predetermined pressure relief zone 21431, reducing the risk of the second weak portion 2145 cracking before the first weak portion 2144. When S2 / S1≤5, the strength of the pressure relief component 214 at the second weak portion 2145 is relatively small, and the obstacle to the predetermined pressure relief area 21431 flipping open is relatively small, making it easier for the predetermined pressure relief area 21431 to flip open under the action of the fluid medium.

[0441] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, wherein, Comprising: A housing having a first wall; A pressure relief component disposed on the first wall, the pressure relief component including a first weak part, the first weak part defining a predetermined pressure relief area, and the pressure relief component being configured to crack along at least a part of the first weak part when the battery cell relieves pressure; Wherein, the pressure relief component further includes a second weak part, and the second weak part is configured to guide at least a part of the predetermined pressure relief area to flip so as to open at least a part of the predetermined pressure relief area.

2. The battery cell according to claim 1, wherein, The housing includes a second wall and a third wall oppositely disposed in a first direction, the first wall connecting the second wall and the third wall, and in the first direction, the second wall has a first outer surface facing away from the interior of the housing, and the third wall has a second outer surface facing away from the interior of the housing; In the first direction, the second weak part is disposed between the first weak part and the first outer surface and / or between the first weak part and the second outer surface.

3. The battery cell according to claim 2, wherein, The pressure relief component is provided with a first groove and a second groove. The pressure relief component forms the first weak part in the area where the first groove is provided, and the pressure relief component forms the second weak part in the area where the second groove is provided. The first groove includes at least one groove segment, and the pressure relief component forms a weak segment in the area where the groove segment is provided. The cross-sectional area of the weak segment perpendicular to its extending direction is a first cross-sectional area, the minimum width of the groove bottom surface of the groove segment is a first width, and the minimum thickness of the weak segment is a first thickness. The first cross-sectional area is equal to the product of the first width and the first thickness; the cross-sectional area of the second weak part perpendicular to its extending direction is a second cross-sectional area, the minimum width of the groove bottom surface of the second groove is a second width, and the minimum thickness of the second weak part is a second thickness. The second cross-sectional area is equal to the product of the second width and the second thickness.

4. The battery cell according to claim 3, wherein, The first width is a1, satisfying: 0.01 mm ≤ a1 ≤ 0.8 mm, optionally, 0.05 mm ≤ a1 ≤ 0.5 mm, optionally, 0.1 mm ≤ a1 ≤ 0.3 mm; and / or The first thickness is h1, satisfying: 0.02 mm ≤ h1 ≤ 1 mm, optionally, 0.04 mm ≤ h1 ≤ 0.6 mm, optionally, 0.08 mm ≤ h1 ≤ 0.4 mm; and / or The second width is a2, satisfying: 0.01 mm ≤ a2 ≤ 0.5 mm, optionally, 0.04 mm ≤ a2 ≤ 0.3 mm, optionally, 0.06 mm ≤ a2 ≤ 0.15 mm; and / or The second thickness is h2, satisfying: 0.1 mm ≤ h2 ≤ 2 mm, optionally, 0.2 mm ≤ h2 ≤ 1.5 mm, optionally, 0.5 mm ≤ h2 ≤ 1 mm.

5. The battery cell according to any one of claims 3-4, wherein, Along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the first weak part and the first outer surface is a second distance, the minimum distance between the first weak part and the second outer surface is a third distance, and the ratio of the difference between the second distance and the third distance to the first distance is greater than or equal to 0 and less than or equal to 0.

1.

6. The battery cell according to claim 5, wherein, The first wall has a third outer surface facing away from the interior of the housing. Along the thickness direction of the first wall, the projection of the first weak part covers the center of the third outer surface.

7. The battery cell according to any one of claims 3-6, wherein, Along the first direction, a second weak part is provided between the first weak part and the first outer surface; Along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the second weak part and the first outer surface is a fourth distance, the minimum distance between the second weak part and the second outer surface is a fifth distance. The first weak part includes at least one weak segment, the cross-sectional area perpendicular to the extension direction of the weak segment is a first cross-sectional area, and the cross-sectional area perpendicular to the extension direction of the second weak part is a second cross-sectional area. When the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or equal to 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1.

5.

8. The battery cell according to claim 7, wherein, The first wall has a third outer surface facing away from the interior of the housing. The third outer surface is rectangular, and the first direction is parallel to the width direction of the rectangle.

9. The battery cell according to claim 7 or 8, wherein The second thickness is greater than or equal to the first thickness, and the second width is less than or equal to the first width.

10. The battery cell according to any one of claims 3-6, wherein, Along the first direction, a second weak part is provided between the first weak part and the first outer surface; Along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the second weak part and the first outer surface is a fourth distance, the minimum distance between the second weak part and the second outer surface is a fifth distance. The first weak part includes at least one weak segment, the cross-sectional area perpendicular to the extension direction of the weak segment is a first cross-sectional area, and the cross-sectional area perpendicular to the extension direction of the second weak part is a second cross-sectional area. When the ratio of the difference between the fifth distance and the fourth distance to the first distance is less than 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1.5 and less than or equal to 5.

11. The battery cell according to claim 10, wherein, The first wall has a third outer surface facing away from the interior of the housing. The third outer surface is rectangular, and the first direction is parallel to the length direction of the rectangle.

12. The battery cell according to claim 10 or 11, wherein, The ratio of the second cross-sectional area to the first cross-sectional area is greater than or equal to 2.13 and less than or equal to 4.

67.

13. The battery cell according to any one of claims 10-12, wherein, The second thickness is greater than or equal to the first thickness, and the second width is greater than or equal to the first width.

14. The battery cell according to any one of claims 7-13, wherein, The first cross-sectional area is S1, satisfying: 0.0002 mm 2 ≤ S1 ≤ 0.8 mm 2 , optionally, 0.002 mm 2 ≤ S1 ≤ 0.3 mm 2 , optionally, 0.008 mm 2 ≤ S1 ≤ 0.12 mm 2 .

15. The battery cell according to any one of claims 7-14, wherein, The second cross-sectional area is S2, satisfying: 0.001 mm 2 ≤ S2 ≤ 1 mm 2 , optionally, 0.008 mm 2 ≤ S2 ≤ 0.45 mm 2 ; optionally, 0.03 mm 2 ≤ S2 ≤ 0.15 mm 2 .

16. The battery cell according to any one of claims 1-15, wherein, The pressure relief component is provided with a second groove, and the pressure relief component forms the second weak portion in a region where the second groove is provided. The second groove is provided on a surface of the pressure relief component facing the interior of the housing.

17. The battery cell according to any one of claims 1-16, wherein, The pressure relief component has a first surface and a second surface arranged opposite to each other in the thickness direction of the first wall, the first surface is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, and the second surface is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided.

18. The battery cell according to claim 17, wherein, The first surface is a surface of the pressure relief component facing away from the interior of the housing, and the second surface is a surface of the pressure relief component facing the interior of the housing.

19. The battery cell according to any one of claims 1-18, wherein, The pressure relief component is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, the first groove includes a first groove section and a second groove section, the first groove section and the second groove section are connected, and the pressure relief component forms a weak section in the area where the first groove section and the second groove section are provided, respectively, and the two weak sections jointly define the predetermined pressure relief area.

20. The battery cell according to any one of claims 1-18, wherein, The pressure relief component is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, the first groove includes a first groove section, a second groove section and a third groove section, the first groove section and the third groove section are arranged opposite to each other, the second groove section connects the first groove section and the third groove section, and the pressure relief component forms a weak section in the area where the first groove section, the second groove section and the third groove section are arranged, respectively, and the three weak sections jointly define the predetermined pressure relief area.

21. The battery cell according to claim 20, wherein, The first weak portion defines two predetermined pressure relief areas, the two predetermined pressure relief areas are respectively located on both sides of the second slot section, and each predetermined pressure relief area is correspondingly provided with at least one second weak portion.

22. The battery cell according to claim 21, wherein, One second weak portion is correspondingly arranged in each predetermined pressure relief area, the pressure relief component is provided with a second groove, the pressure relief component forms the second weak portion in the area provided with the second groove, and the first groove is located between two second grooves.

23. The battery cell according to any one of claims 20-22, wherein, The position where the second slot segment is connected to the first slot segment deviates from the two ends of the first slot segment, and the position where the second slot segment is connected to the third slot segment deviates from the two ends of the third slot segment.

24. The battery cell according to any one of claims 20-23, wherein, The pressure relief component is provided with a second groove, and the second weak portion is formed in a region of the pressure relief component where the second groove is provided, and the first groove section, the second groove section and the third groove section are all spaced apart from the second groove.

25. The battery cell according to claim 24, wherein, The second slot section and the second groove are arranged opposite to each other along a first direction. Along the first direction, the first slot section and the third slot section are arranged at intervals from the second groove.

26. The battery cell according to claim 25, wherein, The first wall has a third outer surface facing away from the interior of the housing, the third outer surface is rectangular, and the first direction is parallel to a length direction or a width direction of the rectangle.

27. The battery cell according to any one of claims 1-26, wherein, The pressure relief component has a first surface and a second surface oppositely arranged in the thickness direction of the first wall. The pressure relief component is provided with a first groove, and the first groove includes multiple levels of grooves arranged in sequence along the direction from the first surface to the second surface. Among two adjacent levels of the grooves, the level of groove farther from the first surface is arranged on the groove bottom surface of the level of groove closer to the first surface; Wherein, the groove bottom wall of the level of groove in the multiple levels of grooves that is farthest from the first surface is the first weak part.

28. The battery cell according to any one of claims 1-27, wherein, The pressure relief component is integrally formed with the first wall.

29. The battery cell according to any one of claims 1-27, wherein, The pressure relief component is separately arranged from the first wall. The first wall is provided with a pressure relief hole, and the pressure relief component is installed on the first wall and covers the pressure relief hole.

30. The battery cell according to any one of claims 1-29, wherein, The battery cell includes an electrode assembly, the electrode assembly is accommodated in the housing, and the first wall supports the electrode assembly along the gravity direction.

31. The battery cell according to any one of claims 1-30, wherein, The battery cell includes an electrode terminal, and the electrode terminal is arranged on a wall of the housing other than the first wall.

32. The battery cell according to claim 31, wherein, The electrode terminal is arranged on the wall of the housing opposite to the first wall.

33. The battery cell according to any one of claims 1-32, wherein, The housing includes: A housing body having an opening; An end cover connected to the housing body and closing the opening; Wherein, the end cover is the first wall, or the housing body includes the first wall.

34. The battery cell according to any one of claims 1-33, characterized in that, The material of the first wall includes steel material or aluminum alloy.

35. A battery, wherein, Including the battery cell according to any one of claims 1-34.

36. An electrical device, wherein, Including the battery cell according to any one of claims 1-34.

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