Battery cell, battery, and electric device

Abstract

The application provides a battery monomer, a battery and an electric device, and relates to the field of batteries. The battery monomer comprises a shell and a pressure relief component, and the shell has a first wall. The pressure relief component is arranged on the first wall, and the pressure relief component comprises a first weak part, the first weak part defines a predetermined pressure relief area, and the pressure relief component is configured to be capable of being split along at least a part of the first weak part when the battery monomer is relieved of pressure. The pressure relief component further comprises a second weak part, and the second weak part is configured to guide at least a part of the predetermined pressure relief area to overturn to open at least a part of the predetermined pressure relief area. The battery monomer is provided with the first weak part and the second weak part, and when the battery monomer is relieved of pressure, the first weak part is split to allow the fluid medium in the battery monomer to flow out for pressure relief. By arranging the second weak part, the predetermined pressure relief area can be guided to overturn and open by the second weak part, which is beneficial to improving the opening speed of the predetermined pressure relief area, realizing rapid pressure relief, and improving the reliability of the battery monomer.

Description

Technical Field

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

[0002] Batteries are widely used in the new energy field, such as in electric vehicles and new energy vehicles, which have become a new trend in the automotive industry. The development of battery technology must consider multiple design factors simultaneously, such as battery life, energy density, discharge capacity, and charge / discharge rate. Furthermore, battery reliability must also be considered. However, current batteries have relatively poor reliability. Summary of the Invention

[0003] The purpose of this application is to provide a battery cell, a battery, and an electrical device, which aims to improve the problem of poor battery reliability in related technologies.

[0004] In a first aspect, embodiments of this application provide a battery cell, the battery cell including a casing and a pressure relief component, the casing having a first wall; the pressure relief component disposed on the first wall, the pressure relief component including a first weak portion defining a predetermined pressure relief area, the pressure relief component being configured to split along at least a portion of the first weak portion when the battery cell is depressurized; wherein, the pressure relief component further includes a second weak portion, the second weak portion being 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.

[0005] In the above technical solution, the battery cell is provided with a first weak part and a second weak part. When the battery cell is depressurized, the first weak part cracks to allow the fluid medium inside the battery cell to flow out and release pressure. By providing the second weak part, the strength of the pressure relief component at the second weak part location is weakened, making the predetermined pressure relief area easier 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 opening speed of the predetermined pressure relief area, achieving rapid pressure relief, reducing the risk of battery cell explosion and fire, and improving the reliability of the battery cell.

[0006] As an optional technical solution in this application embodiment, the outer shell includes a second wall and a third wall disposed opposite to each other along a first direction, the first wall connecting the second wall and the third wall, the second wall having a first outer surface facing away from the interior of the outer shell along the first direction, and the third wall having a second outer surface facing away from the interior of the outer shell; along the first direction, a second weak portion is disposed between the first weak portion and the first outer surface and / or between the first weak portion and the second outer surface.

[0007] 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. 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 is depressurized, the deformation of the depressurization component at the location of the first weak portion is greater than the deformation of the depressurization component at the location of the second weak portion. This facilitates the first weak portion to crack before the second weak portion, allowing the predetermined depressurization 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. 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 is depressurized, the deformation of the depressurization component at the location of the first weak portion is greater than the deformation of the depressurization component at the location of the second weak portion. This facilitates the first weak portion to crack before the second weak portion, allowing the predetermined depressurization area to flip open under the guidance of the second weak portion.

[0008] As an optional technical solution in this application embodiment, the pressure relief component is provided with a first groove and a second groove. The pressure relief component forms a first weak part in the area where the first groove is provided, and forms a second weak part in the area where the second groove is provided. The first groove includes at least one groove segment. 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 extension direction is a first cross-sectional area. The minimum width of the bottom surface of the groove segment is a first width. 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 extension direction is a second cross-sectional area. The minimum width of the bottom surface of the second groove is a second width. 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.

[0009] In the above technical solution, the first and second weak points are formed by creating a first groove and a second groove on 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 point 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 point 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.

[0010] As an optional technical solution in an embodiment of this 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.

[0011] 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 internal gas pressure of the battery cell, thus 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 in a timely manner when the battery cell is depressurized, thus improving the timeliness of depressurization of the battery cell. Therefore, when 0.01 mm ≤ a1 ≤ 0.8 mm, the first width is moderate, the weak section is not easily cracked due to changes in internal gas pressure of the battery cell, and it can crack in a timely manner when the battery cell is depressurized, thus improving the timeliness of depressurization of the battery cell.

[0012] When a1 ≥ 0.05 mm, the larger initial width further reduces the risk of the weak section cracking due to pressure changes within the battery cell, thus improving the reliability of the battery cell. When a1 ≤ 0.5 mm, this allows the weak section to crack more promptly during pressure relief, improving the timeliness of pressure relief. Therefore, when 0.05 mm ≤ a1 ≤ 0.5 mm, a better balance is struck between the reliability of the battery cell and the timeliness of pressure relief.

[0013] When a1 ≥ 0.1 mm, the initial width is larger, which further reduces the risk of the weak section cracking due to changes in internal gas pressure of the battery cell, thus improving the reliability of the battery cell. When a1 ≤ 0.3 mm, it facilitates the more timely cracking of the weak section when the battery cell is depressurized, thus improving the timeliness of depressurization. Therefore, when 0.1 mm ≤ a1 ≤ 0.3 mm, a better balance is struck between the reliability of the battery cell and the timeliness of depressurization.

[0014] When h1 ≥ 0.02 mm, the initial thickness is relatively large, which reduces the risk of the weak section cracking due to changes in internal gas pressure of the battery cell, thus improving the reliability of the battery cell. When h1 ≤ 1 mm, the initial thickness is not too large, which helps the weak section crack in a timely manner when the battery cell is depressurized, thus improving the timeliness of depressurization. Therefore, when 0.02 mm ≤ h1 ≤ 1 mm, the initial thickness is moderate, ensuring that the weak section is not easily cracked due to changes in internal gas pressure of the battery cell, and can crack in a timely manner when the battery cell is depressurized, thus improving the timeliness of depressurization.

[0015] When h1 ≥ 0.04 mm, the initial thickness is greater, which further reduces the risk of the weak section cracking due to changes in internal gas pressure of the battery cell, thus improving the reliability of the battery cell. When h1 ≤ 0.6 mm, this allows the weak section to crack more promptly when the battery cell is depressurized, improving the timeliness of depressurization. Therefore, when 0.04 mm ≤ h1 ≤ 0.6 mm, a better balance is struck between the reliability of the battery cell and the timeliness of depressurization.

[0016] When h1 ≥ 0.08 mm, the initial thickness is greater, which further reduces the risk of the weak section cracking due to changes in internal gas pressure of the battery cell, thus improving the reliability of the battery cell. When h1 ≤ 0.4 mm, this allows the weak section to crack more promptly when the battery cell is depressurized, improving the timeliness of depressurization. Therefore, when 0.08 mm ≤ h1 ≤ 0.4 mm, a better balance is struck between the reliability of the battery cell and the timeliness of depressurization.

[0017] When a2 ≥ 0.01 mm, the second width is relatively large, which reduces the risk of the second weak part cracking due to changes in internal air pressure of the battery cell, thus improving the reliability of the battery cell. When a2 ≤ 0.5 mm, the second width is not too large, which helps to reduce the resistance to the flipping of the predetermined pressure relief zone, facilitating the rapid flipping and opening of the predetermined pressure relief zone, and improving the timeliness of pressure relief of the battery cell. Therefore, when 0.01 mm ≤ a2 ≤ 0.5 mm, the second width is moderate, ensuring that the second weak part is not easily cracked due to changes in internal air pressure of the battery cell, while also facilitating the rapid flipping and opening of the predetermined pressure relief zone, thus improving the timeliness of pressure relief of the battery cell.

[0018] When a2 ≥ 0.04 mm, the second width is larger, which can further reduce the risk of the second weak part cracking due to changes in internal gas pressure of the battery cell, thus improving the reliability of the battery cell. When a2 ≤ 0.3 mm, the resistance to the flipping of the predetermined pressure relief zone is smaller, making it easier for the predetermined pressure relief zone to flip open quickly, which helps improve the timeliness of pressure relief of the battery cell. Therefore, when 0.04 mm ≤ a2 ≤ 0.3 mm, the reliability and timeliness of pressure relief of the battery cell are better balanced.

[0019] When a2 ≥ 0.06 mm, the second width is larger, which can further reduce the risk of the second weak part cracking due to changes in internal gas pressure of the battery cell, thus improving the reliability of the battery cell. When a2 ≤ 0.15 mm, the resistance to the flipping of the predetermined pressure relief zone is smaller, making it easier for the predetermined pressure relief zone to flip and open quickly, thus improving the timeliness of pressure relief of the battery cell. Therefore, when 0.06 mm ≤ a2 ≤ 0.15 mm, the reliability and timeliness of pressure relief of the battery cell are better balanced.

[0020] When h2 ≥ 0.1 mm, the second thickness is relatively large, which reduces the risk of the second weak part cracking due to changes in internal gas pressure of the battery cell, thus improving the reliability of the battery cell. When h2 ≤ 2 mm, the second thickness is not too large, which helps to reduce the resistance to the flipping of the predetermined pressure relief zone, facilitating the rapid flipping and opening of the predetermined pressure relief zone, and improving the timeliness of pressure relief of the battery cell. Therefore, when 0.1 mm ≤ h2 ≤ 2 mm, the second thickness is moderate, the second weak part is not easily cracked due to changes in internal gas pressure of the battery cell, and the predetermined pressure relief zone is easy to flip and open quickly, thus improving the timeliness of pressure relief of the battery cell.

[0021] When h2 ≥ 0.2 mm, the second thickness is greater, which can further reduce the risk of the second weak point cracking due to changes in internal gas pressure of the battery cell, thus improving the reliability of the battery cell. When h2 ≤ 1.5 mm, the resistance to the flipping of the predetermined pressure relief zone is smaller, facilitating the rapid flipping and opening of the predetermined pressure relief zone, which helps improve the timeliness of pressure relief of the battery cell. Therefore, when 0.2 mm ≤ h2 ≤ 1.5 mm, the reliability and timeliness of pressure relief of the battery cell are better balanced.

[0022] When h2 ≥ 0.5 mm, the second thickness is greater, which can further reduce the risk of the second weak part cracking due to changes in internal gas pressure of the battery cell, thus improving the reliability of the battery cell. When h2 ≤ 1 mm, the resistance to the flipping of the predetermined pressure relief zone is smaller, facilitating the rapid flipping and opening of the predetermined pressure relief zone, which helps improve the timeliness of pressure relief of the battery cell. Therefore, when 0.5 mm ≤ h2 ≤ 1 mm, the reliability and timeliness of pressure relief of the battery cell are better balanced.

[0023] As an optional technical solution in this application embodiment, along the first direction, the distance between the first outer surface and the second outer surface is the first distance, the minimum distance between the first weak part and the first outer surface is the second distance, the minimum distance between the first weak part and the second outer surface is the 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.

[0024] 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 part is close to the middle position of the first wall along the first direction. The stiffness of the middle position of the first wall along the first direction is 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 the first weak part cracking before the second weak part, so that the predetermined depressurization area can be flipped open under the guidance of the second weak part, which is conducive to improving the reliability of the battery cell.

[0025] As an optional technical solution in this application embodiment, the first wall has a third outer surface that is away from the interior of the shell, and the projection of the first weak part covers the center of the third outer surface along the thickness direction of the first wall.

[0026] In the above technical solution, along the thickness direction of the first wall, the projection of the first weak part covers the center of the third outer surface. The position of the first weak part is closer to the middle position of the first wall along the first direction, which is more conducive to the first weak part cracking before the second weak part, so that the predetermined pressure relief area can be flipped open under the guidance of the second weak part, which is conducive to improving the reliability of the battery cell.

[0027] As an optional technical solution in this application embodiment, 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 along the first direction 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, the cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area, and 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.

[0028] 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 part deviates significantly from the middle position of the first wall along the first direction. At this time, the second weak part is close to the first outer surface, and the stiffness of the first wall at the position of the second weak part differs significantly from the stiffness at the position of the first weak part. Stiffness has a significant impact on the cracking of both the first and second weak parts. If the influence of stiffness on the first and second weak parts is not considered, the cross-sectional area of ​​the second weak part perpendicular to its extension direction only needs to be greater than the cross-sectional area of ​​the weak segment perpendicular to its extension direction. That is, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1, allowing the first weak part to open and release pressure before the second weak part, with the second weak part acting as a guide for the predetermined pressure relief zone. However, considering that stiffness has a significant 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, therefore, the cross-sectional area of ​​the second weak part can be set to be smaller), a ratio of the second cross-sectional area to the first cross-sectional area greater than 0.7 and less than or equal to 1 can also allow the first weak part to open and release pressure before the second weak part, with the second weak part acting as a guide for the predetermined pressure relief zone. Similarly, since stiffness has a significant impact on the cracking of the first and second weak parts, a ratio of the second cross-sectional area to the first cross-sectional area less than or equal to 1.5 results in lower strength of the pressure relief component at the second weak part location, less resistance to the opening of the predetermined pressure relief zone, making it easier for the predetermined pressure relief zone to open under the action of the fluid medium.

[0029] As an optional technical solution in this application embodiment, the first wall has a third outer surface that is 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.

[0030] In the above technical solution, the first weak part and the second weak part are arranged along the width direction of the third outer surface. The first weak part is closer to the middle position of the first wall along the width direction than the second weak part, and the second weak part is closer to the edge position of the first wall along the width direction than the first weak part. The stiffness has a greater impact on the cracking of the first weak part and the second weak part.

[0031] As an optional technical solution in this application embodiment, the pressure relief component is provided with a first groove and a second groove. The pressure relief component forms a first weak portion in the area where the first groove is provided, and forms a second weak portion in the area where the second groove is provided. The first groove includes at least one groove segment. 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 extension direction is a first cross-sectional area. The minimum width of the bottom surface of the groove segment is a first width. 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 portion perpendicular to its extension direction is a second cross-sectional area. The minimum width of the bottom surface of the second groove is a second width. The minimum thickness of the second weak portion is a second thickness. 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.

[0032] 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 part better guide the opening of the predetermined pressure relief zone, but also, 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 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, the second width is minimized, thereby reducing the area occupied by the second groove on the third outer surface of the pressure relief component.

[0033] As an optional technical solution in this application embodiment, 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 along the first direction 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, the cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area, and 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.

[0034] 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 distance between the second weak part and the middle position of the first wall along the first direction is small. At this time, the second weak part 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 part is similar to that at the first weak part, and the stiffness has little 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 greater than 1.5, the first weak part can open and relieve pressure before the second weak part. The second weak part plays a guiding role in the predetermined pressure relief area, reducing the risk of the second weak part cracking before the first weak part. 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 part is small, and the resistance to the opening of the predetermined pressure relief area is small, making it easier for the predetermined pressure relief area to open under the action of the fluid medium.

[0035] As an optional technical solution in this application embodiment, the first wall has a third outer surface that is 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.

[0036] In the above technical solution, the first weak part and the second weak part are arranged along the length direction of the third outer surface. The first weak part and the second weak part are both closer to the middle position of the first wall along the length direction, and the stiffness has a smaller impact on the cracking of the first weak part and the second weak part.

[0037] As an optional technical solution in this application embodiment, 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.

[0038] 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 weak part is more likely to open and release pressure before the second weak part. The second weak part plays a guiding role in the predetermined pressure relief zone, further reducing the risk that the second weak part will crack before the first weak part. When the ratio of the second cross-sectional area to the first cross-sectional area is less than or equal to 4.67, the pressure relief component has less strength at the second weak part, which reduces the resistance to the opening of the predetermined pressure relief zone, making it easier for the predetermined pressure relief zone to open under the action of the fluid medium.

[0039] As an optional technical solution in this application embodiment, the pressure relief component is provided with a first groove and a second groove. The pressure relief component forms a first weak portion in the area where the first groove is provided, and forms a second weak portion in the area where the second groove is provided. The first groove includes at least one groove segment. 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 extension direction is a first cross-sectional area. The minimum width of the bottom surface of the groove segment is a first width. 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 portion perpendicular to its extension direction is a second cross-sectional area. The minimum width of the bottom surface of the second groove is a second width. The minimum thickness of the second weak portion is a second thickness. 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.

[0040] 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 of different regions of the first wall on the cracking of the weak section and the second weak part can be further reduced, so that the weak section cracks when the battery cell is depressurized, while the second weak part plays a guiding role in the flipping of the predetermined depressurization area.

[0041] As an optional technical solution in this application embodiment, 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 .

[0042] In the above technical solution, when S1 ≥ 0.0002 mm 2 When the first weakest segment has a larger cross-sectional area perpendicular to its extension direction, it is less prone to cracking under external impact, which helps improve the reliability of the battery cell. When S1 ≤ 0.8mm 2 At this point, the cross-sectional area of ​​the first weakest segment perpendicular to its extension direction will not be too large. When the internal pressure of the battery cell reaches the explosion pressure, the first weakest segment is easily broken open under the action of the fluid medium, thus achieving pressure relief. Therefore, when 0.0002mm 2 ≤S1≤0.8mm 2 It can both resist external impacts and easily open for pressure relief when the internal pressure of the battery cell reaches the explosion pressure.

[0043] When S1 ≥ 0.002 mm2 This can further reduce the risk of the first weakest segment cracking under external impact, which is beneficial to improving the reliability of the battery cell. When S1 ≤ 0.3mm 2 When the internal pressure of a single battery cell reaches the explosion pressure, the first weakest section is more likely to crack under the action of the fluid medium, thus releasing pressure. Therefore, when 0.002mm 2 ≤S1≤0.3mm 2 At the same time, it can better resist external impacts and is easy to open the pressure relief when the internal pressure of the battery cell reaches the explosion pressure.

[0044] When S1≥0.008mm 2 This can further reduce the risk of the first weakest segment cracking under external impact, which is beneficial to improving the reliability of the battery cell. When S1 ≤ 0.12mm 2 When the internal pressure of a single battery cell reaches the explosion pressure, the first weakest section is more likely to crack under the action of the fluid medium, thus releasing pressure. Therefore, when 0.008mm 2 ≤S1≤0.12mm 2 At the same time, it can better resist external impacts and is easy to open the pressure relief when the internal pressure of the battery cell reaches the explosion pressure.

[0045] As an optional technical solution in this application embodiment, 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 .

[0046] In the above technical solution, when S2 ≥ 0.001 mm 2 When the second weakest part has a larger cross-sectional area perpendicular to its extension direction, it is less prone to cracking under external impact, which helps improve the reliability of the battery cell. When S2 ≤ 1mm 2 At this time, the cross-sectional area of ​​the second weak part perpendicular to its extension direction will not be too large, which helps to reduce the resistance to the overturning of the predetermined pressure relief zone and facilitates the rapid overturning and opening of the predetermined pressure relief zone. Therefore, when 0.001mm 2 ≤S2≤1mm 2 It can both resist external impacts and facilitate the quick flipping and opening of the predetermined pressure relief zone.

[0047] When S2 ≥ 0.008 mm 2 This can further reduce the risk of the second weak point cracking under external impact, which is beneficial to improving the reliability of the battery cell. When S2 ≤ 0.45mm2 The resistance to the predetermined pressure relief zone flipping is smaller, making it easier for the predetermined pressure relief zone to flip and open quickly. Therefore, when 0.008mm 2 ≤S2≤0.45mm 2 At the same time, it can better resist external impacts and facilitates the quick flipping and opening of the predetermined pressure relief zone.

[0048] When S2 ≥ 0.03 mm 2 This can further reduce the risk of the second weak point cracking under external impact, which is beneficial to improving the reliability of the battery cell. When S2 ≤ 0.15mm 2 The resistance to the predetermined pressure relief zone flipping is smaller, making it easier for the predetermined pressure relief zone to flip and open quickly. Therefore, when 0.03mm 2 ≤S2≤0.15mm 2 At the same time, it can better resist external impacts and facilitates the quick flipping and opening of the predetermined pressure relief zone.

[0049] As an optional technical solution in this application embodiment, the pressure relief component is provided with a second groove, and the pressure relief component forms a second weak part in the area where the second groove is provided. The second groove is provided on the surface of the pressure relief component facing the inside of the outer shell.

[0050] In the above technical solution, the second weak point is formed by creating a second groove on the pressure relief component, which is simple, convenient, and low in cost. In addition, by setting the second groove on the surface of the pressure relief component facing the inside of the outer casing, the tension that the predetermined pressure relief area needs to overcome when flipping is smaller, which facilitates the rapid flipping and opening of the predetermined pressure relief area and helps to improve the reliability of the battery cell.

[0051] As an optional technical solution in this application embodiment, the pressure relief component has a first surface and a second surface that are disposed 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 a first weak part in the area where the first groove is provided. The second surface is provided with a second groove, and the pressure relief component forms a second weak part in the area where the second groove is provided.

[0052] In the above technical solution, the first and second weak points are formed by creating a first groove and a second groove on the pressure relief component, which is simple, convenient, and low in cost. By setting the first groove and the second groove on the first surface and the second surface of the pressure relief component respectively, so that the first groove and the second groove are located on both sides of the pressure relief component, it is convenient to process the first groove and the second groove on both sides of the pressure relief component respectively, which helps to reduce the mutual influence between the first groove and the second groove during the processing.

[0053] As an optional technical solution in this application embodiment, the first surface is the surface of the pressure relief component that is away from the inside of the housing, and the second surface is the surface of the pressure relief component that faces the inside of the housing.

[0054] In the above technical solution, by setting the first groove on the surface of the pressure relief component away from the inside of the outer casing, the tension that the first weak part needs to overcome when cracking is smaller, making it easier to crack. By setting the second groove on the surface of the pressure relief component facing the inside of the outer casing, the tension that the predetermined pressure relief area needs to overcome when flipping is smaller, thereby facilitating the rapid flipping and opening of the predetermined pressure relief area and improving the reliability of the battery cell.

[0055] As an optional technical solution in this application embodiment, the pressure relief component is provided with a first groove, and the pressure relief component forms a first weak part in the area where the first groove is provided. The first groove includes a first groove segment and a second groove segment, and the first groove segment and the second groove segment are connected. The pressure relief component forms a weak segment in the areas where the first groove segment and the second groove segment are provided, and the two weak segments together define the predetermined pressure relief area.

[0056] In the above technical solution, the first slot segment and the second slot segment are interconnected, so that the first slot segment and the second slot segment together define the predetermined pressure relief area. On the one hand, this can increase the pressure relief area of ​​the battery cell and improve the pressure relief rate of the battery cell. On the other hand, it makes the connection between the first slot segment and the second slot segment weaker, making it easier to crack and open the predetermined pressure relief area to release the internal pressure of the battery cell.

[0057] As an optional technical solution in this application embodiment, the pressure relief component is provided with a first groove, and the pressure relief component forms a first weak part in the area where the first groove is provided. The first groove includes a first groove segment, a second groove segment, and a third groove segment. The first groove segment and the third groove segment are arranged opposite to each other, and the second groove segment connects the first groove segment and the third groove segment. The pressure relief component forms a weak segment in the area where the first groove segment, the second groove segment, and the third groove segment are provided, and the three weak segments together define the predetermined pressure relief area.

[0058] In the above technical solution, the first groove includes a first groove segment, a second groove segment, and a third groove segment. The second groove segment connects the first groove segment and the third groove segment, so that the pressure relief component can crack along the first groove segment, the second groove segment, and the third groove segment when the battery cell is depressurized, thereby opening a predetermined pressure relief area to release the internal pressure of the battery cell. The first groove with this structure makes the connection position of the first groove segment and the second groove segment, as well as the connection position of the first groove segment and the third groove segment, weaker, making it easier to crack and open the predetermined pressure relief area for pressure relief, and further improving the pressure relief area and pressure relief rate of the battery cell.

[0059] As an optional technical solution in this application embodiment, the first weak part defines two predetermined pressure relief zones, the two predetermined pressure relief zones are respectively located on both sides of the second groove section, and each predetermined pressure relief zone is provided with at least one second weak part.

[0060] In the above technical solution, the first weak part defines two predetermined pressure relief areas, and each predetermined pressure relief area is provided with at least one second weak part. When the battery cell is depressurized, the two predetermined pressure relief areas are flipped open under the guidance of their corresponding second weak parts, 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.

[0061] As an optional technical solution in this application embodiment, each of the predetermined pressure relief zones is provided with a second weak part, the pressure relief component is provided with a second groove, the pressure relief component forms the second weak part in the area where the second groove is provided, and the first groove is located between the two second grooves.

[0062] In the above technical solution, the predetermined pressure relief area corresponds one-to-one with the second weak point, which reduces the number of second weak points, the number of processing steps for the pressure relief component, and the stress on the pressure relief component. The first groove is positioned between the two second grooves. When the battery cell depressurizes, the pressure relief component can split along the first, second, and third groove segments, thereby opening the two predetermined pressure relief areas. These areas are then flipped open under the guidance of their corresponding second weak points, resulting in a larger pressure relief area for the battery cell. This improves the pressure relief rate and reliability of the battery cell.

[0063] As an optional technical solution in this application embodiment, the position where the second slot segment is connected to the first slot segment is offset from both ends of the first slot segment, and the position where the second slot segment is connected to the third slot segment is offset from both ends of the third slot segment.

[0064] 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, the first groove segment, the second groove segment and the third groove segment form an H-shaped structure, so that both sides of the second groove segment of the first groove can form a predetermined pressure relief area, 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.

[0065] As an optional technical solution in this application embodiment, the pressure relief component is provided with a second groove, and the pressure relief component forms a second weak part in the area where the second groove is provided. The first groove segment, the second groove segment and the third groove segment are all spaced apart from the second groove.

[0066] In the above technical solution, by setting the first groove segment, the second groove segment, and the third groove segment at intervals 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 it cracks along the first groove to relieve pressure can be reduced, and the stress influence between the area where the pressure relief component is set in the first groove and the area where the pressure relief component is set in the second groove can be reduced.

[0067] As an optional technical solution in this application embodiment, the second groove segment and the second groove are arranged opposite to each other along the first direction, and along the first direction, the first groove segment and the third groove segment are both spaced apart from the second groove.

[0068] In the above technical solution, by setting the second groove segment and the second recess opposite each other in the first direction, and setting the first groove segment and the third groove segment apart from the second recess in the first direction, the predetermined pressure relief area defined by the first groove segment, the second groove segment and the third groove segment can be flipped around the area where the pressure relief component is provided with the second recess when it is opened, and the angle of flipping after the predetermined pressure relief area is opened can be increased, so as to improve the pressure relief area of ​​the battery cell.

[0069] As an optional technical solution in this application embodiment, the first wall has a third outer surface that is 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.

[0070] In the above technical solution, the second groove segment and the second recess are arranged along the length or width direction of the third outer surface. Along the length or width direction of the third outer surface, the first groove segment and the third groove segment are spaced apart from the second recess. The third outer surface has a relatively large space in the length or width direction, making it easier to process the first and second recesses. Furthermore, during production, the detonation pressure of the multiple battery cells produced is relatively consistent.

[0071] As an optional technical solution of this application embodiment, the pressure relief component has a first surface and a second surface that are disposed opposite to each other in the thickness direction of the first wall. The pressure relief component is provided with a first groove. The first groove includes multiple levels of grooves arranged sequentially along the direction from the first surface to the second surface. In two adjacent levels of grooves, the first level groove that is far away from the first surface is disposed on the bottom surface of the first level groove that is close to the first surface. The bottom wall of the first level groove that is far away from the first surface is the first weak part.

[0072] In the above technical solution, 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, reducing the risk of cracking, and making the pressure relief component less prone to failure due to cracks at the groove locations, thus improving the reliability of the battery cell. When forming the multi-level grooves, stamping or cold forging can be used, which causes work hardening of the groove walls (changing the grain arrangement, leading to lattice distortion, reducing metal plasticity, and increasing material hardness), enhancing its resistance to external impacts and making it less susceptible to damage from external impacts. This helps reduce the risk of leakage from the pressure relief component.

[0073] As an optional technical solution in this application embodiment, the pressure relief component is integrally formed with the first wall.

[0074] 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 pressure of multiple battery cells produced is relatively consistent.

[0075] As an optional technical solution in this application embodiment, the pressure relief component is separately disposed 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.

[0076] In the above technical solution, the pressure relief component is separately set and installed on the first wall to facilitate processing and manufacturing.

[0077] As an optional technical solution in this application embodiment, the battery cell includes an electrode assembly, which is housed within the outer casing, and the first wall supports the electrode assembly along the direction of gravity.

[0078] In the above technical solution, the first wall supports the electrode assembly along the direction of gravity, and the pressure relief component is set on the first wall. In this way, when the battery cell is depressurized, the ejected fluid medium is less likely to act on other electrical connection components, reducing the risk of short circuit when the battery cell is depressurized.

[0079] As an optional technical solution in this application embodiment, the battery cell includes electrode terminals, which are disposed on the other walls of the housing other than the first wall.

[0080] In the above technical solution, the electrode terminals and the pressure relief components are respectively located on different walls of the casing. When the battery cell is depressurized, the ejected fluid medium is less likely to act on the electrode terminals and cause them to short-circuit, thus reducing the risk of short circuit when the battery cell is depressurized.

[0081] As an optional technical solution in this application embodiment, the electrode terminal is disposed on the wall of the housing opposite to the first wall.

[0082] In the above technical solution, the electrode terminals are located on the wall of the outer casing opposite to the first wall. The electrode terminals are 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 terminals and cause short circuits, which further reduces the risk of short circuits when the battery cell is depressurized.

[0083] As an optional technical solution in this application embodiment, the outer shell includes a housing and an end cap, the housing having an opening; the end cap is connected to the housing and closes the opening; wherein, the end cap is the first wall, or the housing includes the first wall.

[0084] In the above technical solutions, when the end cap is the first wall, the pressure relief component is located on the end cap, making manufacturing simple and convenient. When the housing includes the first wall, the pressure relief component is located 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, which helps to reduce the risk of short circuits in individual battery cells.

[0085] Secondly, embodiments of this application also provide a battery, the battery comprising the aforementioned battery cell.

[0086] Thirdly, embodiments of this application also provide an electrical device, which includes the aforementioned battery cell. Attached Figure Description

[0087] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0088] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0089] Figure 2 Exploded views of the battery structure provided in some embodiments of this application;

[0090] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0091] Figure 4 Exploded views of the structure of a single battery cell provided in some embodiments of this application;

[0092] Figure 5 A bottom view of the casing of a battery cell provided in some embodiments of this application;

[0093] Figure 6 A partial cross-sectional view of the casing of a battery cell provided in some embodiments of this application;

[0094] Figure 7 for Figure 6 A magnified view of part A of the outer casing shown;

[0095] Figure 8 A bottom view of the casing of a battery cell provided in some embodiments of this application;

[0096] Figure 9 A bottom view of the casing of a battery cell provided in some embodiments of this application;

[0097] Figure 10 A bottom view of the casing of a battery cell provided in other embodiments of this application;

[0098] Figure 11 The following is a bottom view of the casing of a battery cell provided in some embodiments of this application.

[0099] Icons: 1000 - Vehicle; 100 - Battery; 10 - Housing; 11 - First Housing Body; 12 - Second Housing Body; 20 - Battery Cell; 21 - Outer Shell; 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-Stage Recess; 2142 - Second-Stage Recess; 2 143-Third-stage groove; 21431-Predetermined pressure relief area; 2143a-First groove segment; 2143b-Second groove segment; 2143c-Third groove segment; 2144-First weak point; 2145-Second weak point; 21451-Second groove; 2146-First groove; 215-Housing; 2151-Opening; 216-End cap; 22-Electrode assembly; 221-Electrode tab; 23-Electrode terminal; 24-Current collector; 200-Controller; 300-Motor. Detailed Implementation

[0100] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0101] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0102] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0103] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0104] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0105] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0106] In this application, "multiple" means two or more (including two).

[0107] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0108] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0109] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0110] 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.

[0111] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0112] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be 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. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0113] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional 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. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide 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, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0114] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0115] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0116] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0117] 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.

[0118] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0119] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. 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, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0120] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0121] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0122] In some embodiments, the separator is a separator membrane. The separator membrane can be of various types, and any known porous separator membrane with good chemical and mechanical stability can be selected.

[0123] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0124] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0125] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0126] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0127] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl 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. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0128] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0129] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0130] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0131] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0132] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0133] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0134] In some implementations, the electrode assembly is a stacked structure.

[0135] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0136] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0137] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0138] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0139] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0140] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0141] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0142] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0143] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include, but are not limited to, square battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0144] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0145] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0146] In some embodiments, the battery can be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0147] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0148] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0149] Batteries are widely used in the new energy field, such as in electric vehicles and new energy vehicles, which have become a new trend in the automotive industry. The development of battery technology must consider multiple design factors simultaneously, such as battery life, energy density, discharge capacity, and charge / discharge rate. Furthermore, battery reliability must also be considered. However, current batteries have relatively poor reliability.

[0150] To improve the reliability of individual battery cells, existing technologies involve welding a pressure relief mechanism onto the cell. This mechanism has a weak point that defines the pressure relief section. When the internal pressure of the battery cell reaches the explosion pressure, the weak point breaks open, and the pressure relief section opens to release the internal pressure of the battery cell, thereby reducing the risk of explosion and fire.

[0151] However, when a battery cell is depressurized, often only a small part of the weakest section cracks. In this case, the depressurization section may not be able to open, or it may only open a small opening, or although it may open completely, the opening speed may be slow, resulting in a slow depressurization speed. This makes it impossible to quickly release the pressure inside the battery cell, leaving the battery cell with a high risk of explosion and fire, and resulting in poor reliability of the battery cell.

[0152] In view of this, embodiments of this application provide a battery cell, which includes a casing and a pressure relief component. The casing has a first wall, and the pressure relief component is disposed on the first wall. The pressure relief component includes a first weak portion defining a predetermined pressure relief area. The pressure relief component is configured to split along at least a portion of the first weak portion when the battery cell is depressurized. The pressure relief component further includes a second weak portion configured to guide at least a portion of the predetermined pressure relief area to flip over, thereby opening at least a portion of the predetermined pressure relief area.

[0153] The battery cell has a first weak point and a second weak point. When the battery cell is depressurized, the first weak point cracks to allow the fluid medium inside the battery cell to flow out and release pressure. By setting the second weak point, the strength of the pressure relief component at the second weak point is weakened, 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 opening speed, achieving rapid pressure relief, reducing the risk of battery cell explosion and fire, and improving the reliability of the battery cell.

[0154] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system for such an electrical device can be constructed using battery cells and batteries disclosed in this application, which helps to improve the reliability of the battery cells.

[0155] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0156] For ease of explanation, the following embodiments will be described using a vehicle as an example of an electrical device according to an embodiment of this application.

[0157] Please refer to Figure 1 , Figure 1This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery 100 is disposed inside the vehicle 1000. The battery 100 can be disposed at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source or general power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 controls the battery 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0158] In some embodiments of this application, the battery 100 can not only serve as the operating power or power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0159] Please refer to Figure 2 and Figure 3 , Figure 2 This is an exploded view of the structure of the battery 100 provided in some embodiments of this application. Figure 3 This is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of this application. The battery 100 includes a housing 10 and a battery cell 20, which is housed within the housing 10.

[0160] The housing 10 provides assembly space for the battery cell 20, and can adopt various structures. In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, which overlap each other, and together define an assembly space for accommodating the battery cell 20. The second housing body 12 may be a hollow structure open at one end, and the first housing body 11 may be a plate-like structure, with the first housing body 11 covering the open side of the second housing body 12 so that the first housing body 11 and the second housing body 12 together define the assembly space; alternatively, the first housing body 11 and the second housing body 12 may both be hollow structures open on one side, with the open side of the first housing body 11 covering the open side of the second housing body 12.

[0161] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder, a cuboid, or a cube. For example, in... Figure 2 In the middle, the shape of box 10 is a cuboid.

[0162] In battery 100, there can be one or more battery cells 20 disposed within housing 10. When there are multiple battery cells 20 disposed within housing 10, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed configuration, and then the entire assembly of multiple battery cells 20 is housed within housing 10. Alternatively, battery 100 can also be composed of multiple battery cells 20 first connected in series, in parallel, or in a mixed configuration to form a battery module, and then multiple battery modules are connected in series, in parallel, or in a mixed configuration to form a whole, which is then housed within housing 10.

[0163] In some embodiments, the battery 100 may also include other structures. For example, the battery 100 may also include a busbar for connecting multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0164] 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 to these. The battery cell 20 can be in the form of a cuboid, cylinder, prism, or other shapes. For example, in... Figure 3 In the middle, the battery cell 20 has a cuboid structure.

[0165] According to some embodiments of this application, please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 , Figure 4 Exploded views of the structure of a battery cell 20 provided in some embodiments of this application. Figure 5 A bottom view of the casing 21 of a battery cell 20 provided in some embodiments of this application. Figure 6 A partial cross-sectional view of the casing 21 of a battery cell 20 provided in some embodiments of this application. Figure 7 for Figure 6 The image shows a partial enlarged view of point A on the outer casing 21. This application embodiment provides a battery cell 20, which includes an outer casing 21 and a pressure relief component 214. The outer casing 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 weak portion 2144 defining a predetermined pressure relief area 21431. The pressure relief component 214 is configured 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 also 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, thereby opening at least a portion of the predetermined pressure relief area 21431.

[0166] Battery cell 20 refers to the smallest unit that makes up battery 100.

[0167] The outer casing 21 includes an end cap 216 and a housing 215, the housing 215 having an opening 2151, and the end cap 216 being connected to the housing 215 and closing the opening 2151.

[0168] End cap 216 refers to a component that covers the opening 2151 of housing 215 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 216 can be adapted to the shape of housing 215 to fit the housing 215. Optionally, end cap 216 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that end cap 216 is not easily deformed under pressure and impact, enabling battery cell 20 to have higher structural strength and improved safety performance. The material of end cap 216 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose special limitations on this. In some embodiments, battery cell 20 also includes an insulating member disposed inside end cap 216. The insulating member can be used to isolate the electrical connection components inside housing 215 from end cap 216 to reduce the risk of short circuit. For example, the insulating member can be plastic, rubber, etc.

[0169] The housing 215 is a component used to cooperate with the end cap 216 to form the internal environment of the battery cell 20. This internal environment can 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 can close the opening 2151 to form the internal environment of the battery cell 20. Alternatively, the end cap 216 and the housing 215 can be integrated. Specifically, the end cap 216 and the housing 215 can form a common mating surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 215, the end cap 216 closes the housing 215. The housing 215 can have various shapes and sizes, such as cuboid, cylindrical, or hexagonal prism. 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. This application embodiment does not impose any special restrictions on this.

[0170] Electrode assembly 22 is the component in the battery cell 20 where electrochemical reactions occur. The casing 21 may contain one or more electrode assemblies 22. The electrode assembly 22 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the electrode assembly 22, while the portions of the positive and negative electrode sheets without active material each constitute a tab 221. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery 100, the positive and negative active materials react with the electrolyte.

[0171] The first wall 211 can be an end cap 216 of the outer casing 21, or it can be a wall of the housing 215 of the outer casing 21. For example, in... Figure 3 and Figure 4 In this embodiment, the first wall 211 is the bottom wall of the housing 215, which is disposed opposite to the end cap 216. In other embodiments, the first wall 211 may also be a side wall of the housing 215 that is adjacent to and connected to the end cap 216.

[0172] The pressure relief component 214 can be a component mounted on the first wall 211, in which case the pressure relief component 214 and the first wall 211 are separately configured and connected. For example, the pressure relief component 214 is an explosion-proof plate mounted on the first wall 211. The pressure relief component 214 can also be part of the first wall 211, in which 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 located on the end cap 216, then the end cap 216 is the first wall 211. When the pressure relief component 214 is located on the bottom wall of the housing 215, then the bottom wall is the first wall 211. When the pressure relief component 214 is located on the side wall of the housing 215, then the side wall is the first wall 211.

[0173] The first weak portion 2144 serves a pressure relief function, allowing the pressure relief component 214 to crack along the first weak portion 2144 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, thereby releasing the internal pressure of the battery cell 20. In some embodiments, the strength of the pressure relief component 214 at the location of the first weak portion 2144 may be lower than the strength at other locations of the pressure relief component 214, so that the first weak portion 2144 can crack under the internal pressure when the internal pressure or temperature of the battery cell 20 reaches the predetermined value, thereby releasing the internal pressure of the battery cell 20. In other embodiments, the melting point of the pressure relief component 214 at the location of the first weak portion 2144 may be lower than the melting point at other locations of the pressure relief component 214. Thus, the first weak portion 2144 can crack under high temperature when the internal pressure or temperature of the battery cell 20 reaches the predetermined value, thereby releasing the internal pressure of the battery cell 20.

[0174] The first weak portion 2144 defines a predetermined pressure relief area 21431. When the battery cell 20 is depressurized, the first weak portion 2144 cracks along the edge of the predetermined pressure relief area 21431, so that the predetermined pressure relief area 21431 can be opened to relieve pressure.

[0175] The second weak portion 2145 serves to guide at least a portion of the predetermined pressure relief zone 21431 to flip open. Optionally, the second weak portion 2145 has higher strength than the first weak portion 2144. When the battery cell 20 is depressurized, the first weak portion 2144 cracks first to allow the fluid medium inside the battery cell 20 to flow out and relieve pressure. Subsequently, under the action of the fluid medium, the predetermined pressure relief zone 21431 can flip outward about the second weak portion 2145 as the rotation axis to open a larger opening 2151, achieving rapid pressure relief.

[0176] The battery cell 20 is provided with a first weak portion 2144 and a second weak portion 2145. When the battery cell 20 is depressurized, the first weak portion 2144 cracks to allow the fluid medium inside the battery cell 20 to flow out and release 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, achieving rapid pressure relief, reducing the risk of battery cell 20 explosion and fire, and improving the reliability of the battery cell 20.

[0177] In some embodiments, see Figure 4 As shown, the battery cell 20 may also include an electrode terminal 23, which is insulated and mounted on the housing 21 and electrically connected to the electrode assembly 22 to output or input electrical energy of the battery cell 20.

[0178] It should be noted that the electrode terminal 23 is insulated and mounted on the housing 21, meaning that there is no electrical connection between the electrode terminal 23 and the housing 21.

[0179] Among them, Figure 3 and Figure 4 In the battery cell 20, there are two electrode terminals 23, which are spaced apart on the end cap 216. Correspondingly, each electrode assembly 22 has two tabs 221, and the polarities of the two tabs 221 are opposite. The two electrode terminals 23 are electrically connected to the two tabs 221 of the electrode assembly 22 respectively, so as to realize the input or output of the positive and negative electrodes of the battery cell 20.

[0180] For example, the electrode terminal 23 can be made of various materials, such as copper, iron, aluminum, steel or aluminum alloy.

[0181] Optionally, the structure in which the electrode terminal 23 is mounted on the housing 21 can be varied; for example, in Figure 3 and Figure 4 In this embodiment, 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 to this. In other embodiments, both electrode terminals 23 may be mounted on the housing 215 of the housing 21. Similarly, one electrode terminal 23 may be mounted on the housing 215 of the housing 21, and the other electrode terminal 23 may be mounted on the end cap 216 of the housing 21.

[0182] In some embodiments, see Figure 4 As shown, the battery cell 20 may also include two current collectors 24, both of which are disposed inside the housing 21. Each current collector 24 is used to connect an electrode terminal 23 and a tab 221 of the same polarity in multiple electrode assemblies 22, so as to realize the electrical connection between the electrode terminal 23 and the electrode assembly 22, which helps to reduce the assembly difficulty between the tab 221 and the electrode terminal 23.

[0183] For example, the material of the current collector 24 can be various, such as copper, iron, aluminum, steel or aluminum alloy.

[0184] In some embodiments, please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The outer casing 21 includes a second wall 212 and a third wall 213 disposed opposite to each other along a first direction, with the 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 outer casing 21, and the third wall 213 has a second outer surface 2131 facing away from the interior of the outer casing 21. Along the first direction, a second weak portion 2145 is provided 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.

[0185] Please refer to Figure 5 , Figure 6 and Figure 7 The first direction is the X direction shown in the figure.

[0186] Along the first direction, the second wall 212 and the third wall 213 are disposed opposite to 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 two adjacent and interconnected walls of the outer shell 21, and the first wall 211 and the third wall 213 are two adjacent and interconnected walls of the outer shell 21, and the second wall 212 and the third wall 213 are two oppositely disposed walls of the outer shell 21.

[0187] 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 side walls of the housing 215 that are opposite to each other. When the first wall 211 is a side wall of the housing 215, the second wall 212 can be an end cap 216, and the third wall 213 can be the bottom wall of the housing 215.

[0188] The first outer surface 2121 is the surface of the second wall 212 that faces away from the interior of the outer shell 21 along the first direction. The second outer surface 2131 is the surface of the third wall 213 that faces away from the interior of the outer shell 21 along the first direction.

[0189] Along the first direction, a 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 a portion of the second weak portions 2145 located between the first weak portion 2144 and the first outer surface 2121, and another portion of the second weak portions 2145 located between the first weak portion 2144 and the second outer surface 2131. Please refer to... Figure 5 In the embodiment shown in the figure, the pressure relief component 214 includes two second weak parts 2145. Along the first direction, one second weak part 2145 is located between the first weak part 2144 and the first outer surface 2121, and the other second weak part 2145 is located between the first weak part 2144 and the second outer surface 2131.

[0190] 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. The stiffness of the location of the first weak portion 2144 is less than the stiffness of the location of the second weak portion 2145. When the battery cell 20 is depressurized, the deformation of the depressurization component 214 at the location of the first weak portion 2144 is greater than the deformation of the depressurization component 214 at the location of the second weak portion 2145. This is beneficial for the first weak portion 2144 to crack before the second weak portion 2145, so that the predetermined depressurization 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. The stiffness of the location of the first weak portion 2144 is less than the stiffness of the location of the second weak portion 2145. When the battery cell 20 is depressurized, the deformation of the depressurization component 214 at the location of the first weak portion 2144 is greater than the deformation of the depressurization component 214 at the location of the second weak portion 2145. This is beneficial for the first weak portion 2144 to crack before the second weak portion 2145, so that the predetermined depressurization area 21431 can be flipped open under the guidance of the second weak portion 2145.

[0191] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 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 weak portion 2144 in the area where the first groove 2146 is provided, and forms a second weak portion 2145 in the area 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 weak segment in the area where the groove segment is provided. The cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area, the minimum width of the bottom surface of the groove segment is a first width, the minimum thickness of the weak segment is a 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 2145 perpendicular to its extension direction is a second cross-sectional area, the minimum width of the bottom surface of the second groove 21451 is a second width, the minimum thickness of the second weak portion 2145 is a second thickness, and the second cross-sectional area is equal to the product of the second width and the second thickness.

[0192] The first groove 2146 and the second groove 21451 can be disposed on the same side of the pressure relief component 214, or they can be disposed 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 disposed opposite to each other, wherein the first surface 2111 faces away from the interior of the outer casing 21, and the second surface 2112 faces the interior of the outer casing 21. The first groove 2146 and the second groove 21451 can both be disposed on the first surface 2111, or the first groove 2146 and the second groove 21451 can both be disposed on the second surface 2112, in which 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 disposed on the first surface 2111, and the other of the first groove 2146 and the second groove 21451 can be disposed on the second surface 2112. In this case, the first groove 2146 and the second groove 21451 are disposed on both sides of the pressure relief component 214. Optionally, the first groove 2146 is disposed on the first surface 2111, and the second groove 21451 is disposed on the second surface 2112.

[0193] The first groove 2146 and the second groove 21451 can be formed by various methods, such as stamping or cold heading. Taking the stamping of the first groove 2146 as an example, 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. Taking the stamping of the second groove 21451 as an example, 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.

[0194] 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 segment corresponds one-to-one with the groove segment.

[0195] The first weak portion 2144 includes at least one weak segment, which is a straight structure. The first cross-sectional area represents the cross-sectional area of ​​the cross section perpendicular to the extension direction of the weak segment. Please refer to... Figure 7 , Figure 7 The cross-section shown in the image is a honeycomb-shaped filling pattern perpendicular to the extension direction of the weak segment. The area filled by the honeycomb-shaped filling pattern is the first cross-sectional area, or S1.

[0196] In some embodiments, the location of the weak segment can be determined by tomography, and the cross-sectional area of ​​the cross section perpendicular to the extension direction of the weak segment can be determined, that is, S1 can be obtained by tomography.

[0197] The first width is the minimum width of the bottom surface of the groove segment. Please refer to... Figure 7 , Figure 7 The first width is indicated by a1. It should be noted that the ends of the groove segment are generally rounded. When measuring the first width, the minimum width of the groove segment outside the rounded transition area should be measured, that is, the measurement should avoid the rounded transition position.

[0198] The first thickness is the minimum thickness of the weakest section. Please refer to... Figure 7 , Figure 7 The first thickness is indicated by h1. The first thickness can be obtained from the difference between the thickness of the pressure relief component 214 and the depth of the groove section, or by tomographic scanning, or by measurement after the weak section cracks.

[0199] The first cross-sectional area is equal to the product of the first width and the first thickness, i.e., 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 obtaining the first cross-sectional area, the area where the groove segment's fillet transitions should be avoided.

[0200] The second weak point 2145 can be a straight structure. The second cross-sectional area represents the cross-sectional area of ​​the section perpendicular to the extending direction of the second weak point 2145. Please refer to... Figure 6 , Figure 6 The cross-section shown in the middle is a mesh-like filling pattern perpendicular to the extension direction of the second weak part 2145. The area filled by the mesh-like filling pattern is the second cross-sectional area, or S2.

[0201] In some embodiments, the location 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.

[0202] The second width is the minimum width of the bottom surface of the second groove 21451. Please refer to... Figure 6 , Figure 6 The second width is indicated by a2. It should be noted that the end of the second groove 21451 is generally rounded. When measuring the second width, the minimum width of the area outside the rounded transition area of ​​the second groove 21451 should be measured, that is, the measurement should avoid the rounded transition position.

[0203] The second thickness is the minimum thickness of the second weakest part 2145. Please refer to... Figure 6 , Figure 6 The second thickness is indicated by h2. The second thickness can be obtained from the difference between the thickness of the pressure relief component 214 and the depth of the second groove 21451, or by tomographic scanning, or by measuring after cutting open the second weak part 2145.

[0204] The second cross-sectional area is equal to the product of the second width and the second thickness, i.e., 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 obtaining the second cross-sectional area, the area where the second groove's fillet transitions should be avoided.

[0205] The first weak section 2144 and the second weak section 2145 are formed by creating a first groove 2146 and a second groove 21451 on the pressure relief component 214. This method is simple, convenient, and low-cost. The first cross-sectional area is equal to the product of the first width and the first thickness, meaning that the cross-section of the weak section 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, meaning that the cross-section of the second weak section 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.

[0206] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the first width is a1, which satisfies: 0.01mm≤a1≤0.8mm.

[0207] 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.

[0208] When a1 ≥ 0.01 mm, the first width is relatively large, which reduces the risk of the weak section cracking due to changes in internal gas pressure of the battery cell 20, thus improving the reliability of the battery cell 20. When a1 ≤ 0.8 mm, the first width is not too large, which helps the weak section crack in time when the battery cell 20 is depressurized, thus improving the timeliness of depressurization of the battery cell 20. Therefore, when 0.01 mm ≤ a1 ≤ 0.8 mm, the first width is moderate, the weak section is not easily cracked due to changes in internal gas pressure of the battery cell 20, and it can crack in time when the battery cell 20 is depressurized, thus improving the timeliness of depressurization of the battery cell 20.

[0209] In some embodiments, 0.05mm ≤ a1 ≤ 0.5mm.

[0210] 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.

[0211] When a1 ≥ 0.05 mm, the first width is larger, which can further reduce the risk of the weak section cracking due to changes in internal gas pressure of the battery cell 20, thus improving the reliability of the battery cell 20. When a1 ≤ 0.5 mm, it is beneficial for the weak section to crack more promptly when the battery cell 20 is depressurized, thus improving the timeliness of depressurization of the battery cell 20. Therefore, when 0.05 mm ≤ a1 ≤ 0.5 mm, the reliability and timeliness of depressurization of the battery cell 20 are better balanced.

[0212] Optionally, 0.1mm ≤ a1 ≤ 0.3mm.

[0213] The first width can be a1 = 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.

[0214] When a1 ≥ 0.1 mm, the first width is larger, which can further reduce the risk of the weak section cracking due to changes in internal gas pressure of the battery cell 20, thus improving the reliability of the battery cell 20. When a1 ≤ 0.3 mm, it helps the weak section crack more promptly when the battery cell 20 is depressurized, thus improving the timeliness of depressurization of the battery cell 20. Therefore, when 0.1 mm ≤ a1 ≤ 0.3 mm, the reliability and timeliness of depressurization of the battery cell 20 are better balanced.

[0215] In some embodiments, the first thickness is h1, which satisfies: 0.02mm≤h1≤1mm.

[0216] 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.

[0217] When h1 ≥ 0.02 mm, the initial thickness is relatively large, which reduces the risk of the weak section cracking due to changes in internal gas pressure of the battery cell 20, thus improving the reliability of the battery cell 20. When h1 ≤ 1 mm, the initial thickness is not too large, which helps the weak section crack in time when the battery cell 20 is depressurized, thus improving the timeliness of depressurization of the battery cell 20. Therefore, when 0.02 mm ≤ h1 ≤ 1 mm, the initial thickness is moderate, ensuring that the weak section is not easily cracked due to changes in internal gas pressure of the battery cell 20, and can crack in time when the battery cell 20 is depressurized, thus improving the timeliness of depressurization of the battery cell 20.

[0218] In some embodiments, 0.04mm ≤ h1 ≤ 0.6mm.

[0219] 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.

[0220] When h1 ≥ 0.04 mm, the initial thickness is greater, which further reduces the risk of the weak section cracking due to changes in internal gas pressure of the battery cell 20, thus improving the reliability of the battery cell 20. When h1 ≤ 0.6 mm, this facilitates the more timely cracking of the weak section when the battery cell 20 is depressurized, thus improving the timeliness of depressurization of the battery cell 20. Therefore, when 0.04 mm ≤ h1 ≤ 0.6 mm, a better balance is struck between the reliability and timeliness of depressurization of the battery cell 20.

[0221] Optionally, 0.08mm≤h1≤0.4mm.

[0222] The first thickness can be h1 = 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, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, etc.

[0223] When h1 ≥ 0.08 mm, the initial thickness is greater, which further reduces the risk of the weak section cracking due to changes in internal gas pressure of the battery cell 20, thus improving the reliability of the battery cell 20. When h1 ≤ 0.4 mm, this allows the weak section to crack more promptly when the battery cell 20 is depressurized, improving the timeliness of depressurization. Therefore, when 0.08 mm ≤ h1 ≤ 0.4 mm, a better balance is struck between the reliability and timeliness of depressurization of the battery cell 20.

[0224] In some embodiments, the second width is a2, satisfying: 0.01mm≤a2≤0.5mm.

[0225] The second width can be a2 = 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, etc.

[0226] When a2 ≥ 0.01 mm, the second width is relatively large, which reduces the risk of the second weak part 2145 cracking due to changes in internal air pressure of the battery cell 20, thus improving the reliability of the battery cell 20. When a2 ≤ 0.5 mm, the second width is not too large, which helps to reduce the resistance to the flipping of the predetermined pressure relief area 21431, facilitating the rapid flipping and opening of the predetermined pressure relief area 21431, and improving the timeliness of pressure relief of the battery cell 20. Therefore, when 0.01 mm ≤ a2 ≤ 0.5 mm, the second width is moderate, ensuring that the second weak part 2145 is not easily cracked due to changes in internal air pressure of the battery cell 20, and that the predetermined pressure relief area 21431 can be quickly flipped and opened, thus improving the timeliness of pressure relief of the battery cell 20.

[0227] In some embodiments, 0.04mm ≤ a2 ≤ 0.3mm.

[0228] 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.

[0229] When a2 ≥ 0.04 mm, the second width is larger, which can further reduce the risk of the second weak part 2145 cracking due to changes in air pressure inside the battery cell 20, thus improving the reliability of the battery cell 20. When a2 ≤ 0.3 mm, the resistance to the flipping of the predetermined pressure relief area 21431 is smaller, making it easier for the predetermined pressure relief area 21431 to flip and open quickly, thus improving the timeliness of pressure relief of the battery cell 20. Therefore, when 0.04 mm ≤ a2 ≤ 0.3 mm, the reliability and timeliness of pressure relief of the battery cell 20 are better balanced.

[0230] Optionally, 0.06mm ≤ a2 ≤ 0.15mm.

[0231] 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, 0.11mm, 0.115mm, 0.12mm, 0.125mm, 0.13mm, 0.135mm, 0.14mm, 0.145mm, 0.15mm.

[0232] When a2 ≥ 0.06 mm, the second width is larger, which can further reduce the risk of the second weak part 2145 cracking due to changes in air pressure inside the battery cell 20, thus improving the reliability of the battery cell 20. When a2 ≤ 0.15 mm, the resistance to the flipping of the predetermined pressure relief area 21431 is smaller, making it easier for the predetermined pressure relief area 21431 to flip and open quickly, thus improving the timeliness of pressure relief of the battery cell 20. Therefore, when 0.06 mm ≤ a2 ≤ 0.15 mm, the reliability and timeliness of pressure relief of the battery cell 20 are better balanced.

[0233] In some embodiments, the second thickness is h2, satisfying: 0.1mm≤h2≤2mm.

[0234] 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.

[0235] When h2 ≥ 0.1 mm, the second thickness is relatively large, which reduces the risk of the second weak part 2145 cracking due to changes in internal air pressure of the battery cell 20, thus improving the reliability of the battery cell 20. When h2 ≤ 2 mm, the second thickness is not too large, which helps to reduce the resistance to the flipping of the predetermined pressure relief area 21431, facilitating the rapid flipping and opening of the predetermined pressure relief area 21431, and improving the timeliness of pressure relief of the battery cell 20. Therefore, when 0.1 mm ≤ h2 ≤ 2 mm, the second thickness is moderate, the second weak part 2145 is not easily cracked due to changes in internal air pressure of the battery cell 20, and the predetermined pressure relief area 21431 is easy to flip and open quickly, thus improving the timeliness of pressure relief of the battery cell 20.

[0236] In some embodiments, 0.2mm ≤ h2 ≤ 1.5mm.

[0237] 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.

[0238] When h2 ≥ 0.2 mm, the second thickness is greater, which can further reduce the risk of the second weak part 2145 cracking due to changes in air pressure inside the battery cell 20, thus improving the reliability of the battery cell 20. When h2 ≤ 1.5 mm, the resistance to the flipping of the predetermined pressure relief area 21431 is smaller, making it easier for the predetermined pressure relief area 21431 to flip and open quickly, thus improving the timeliness of pressure relief of the battery cell 20. Therefore, when 0.2 mm ≤ h2 ≤ 1.5 mm, the reliability and timeliness of pressure relief of the battery cell 20 are better balanced.

[0239] Optionally, 0.5mm ≤ h2 ≤ 1mm.

[0240] 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.

[0241] When h2 ≥ 0.5 mm, the second thickness is greater, which can further reduce the risk of the second weak part 2145 cracking due to changes in air pressure inside the battery cell 20, thus improving the reliability of the battery cell 20. When h2 ≤ 1 mm, the resistance to the flipping of the predetermined pressure relief area 21431 is smaller, making it easier for the predetermined pressure relief area 21431 to flip and open quickly, thus improving the timeliness of pressure relief of the battery cell 20. Therefore, when 0.5 mm ≤ h2 ≤ 1 mm, the reliability and timeliness of pressure relief of the battery cell 20 are better balanced.

[0242] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, along the first direction, the distance between the first outer surface 2121 and the second outer surface 2131 is the first distance, the minimum distance between the first weak portion 2144 and the first outer surface 2121 is the second distance, and the minimum distance between the first weak portion 2144 and the second outer surface 2131 is the third distance. 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.

[0243] The first distance represents the distance between the first outer surface 2121 along the first direction and the second outer surface 2131 along the first direction. Please refer to [reference needed]. Figure 5 The diagram shows the first distance, which is L. Multiple measurements can be taken and the average value calculated.

[0244] The second distance represents the minimum distance between the first weak point 2144 and the first outer surface 2121 along the first direction. Please refer to [reference needed]. Figure 5 The figure shows the second distance, which is L1. During measurement, the distance between the position of the first weak part 2144 closest to the first outer surface 2121 and the first outer surface 2121 can be measured. Similarly, multiple measurements can be taken and the average value can be taken to reduce measurement error.

[0245] The third distance represents the minimum distance between the first weak point 2144 and the second outer surface 2131 along the first direction. Please refer to [reference needed]. Figure 5The figure shows the third distance, and the second distance is L2. During measurement, the distance between the position of the first weak part 2144 closest to the second outer surface 2131 and the second outer surface 2131 can be measured. Similarly, multiple measurements can be taken and the average value can be taken to reduce measurement error.

[0246] The difference between the second and third distances represents the result of subtracting the smaller of the two distances from the larger one.

[0247] "The ratio of the difference between the second and third distances 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.

[0248] 0≤|L1-L2| / L≤0.1 indicates that the distance from the first weak part 2144 to the first outer surface 2121 and the distance from the first weak part 2144 to the second outer surface 2131 are relatively close, that is, the first weak part 2144 is roughly located in the middle of the first wall 211.

[0249] 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.

[0250] When 0≤|L1-L2| / L≤0.1, the position of the first weak part 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 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 the first weak part 2144 cracking before the second weak part 2145. This allows the predetermined depressurization area 21431 to be flipped open under the guidance of the second weak part 2145, which is beneficial to improving the reliability of the battery cell 20.

[0251] In some embodiments, the first wall 211 has a third outer surface 2113 facing away from the interior of the housing 21, and the projection of the first weak portion 2144 along the thickness direction of the first wall 211 covers the center of the third outer surface 2113.

[0252] Please refer to Figure 6 and Figure 7 The thickness direction of the first wall 211 is the Y direction shown in the figure. This first direction intersects with the thickness direction of the first wall 211. Figure 6 and Figure 7 In the embodiment shown, the first direction is perpendicular to the thickness direction of the first wall 211.

[0253] Along the thickness direction of the first wall 211, the pressure relief component 214 has a first surface 2111 and a second surface 2112 disposed opposite to each other, wherein the first surface 2111 faces away from the interior of the outer casing 21, and the second surface 2112 faces the interior of the outer casing 21. When the pressure relief component 214 is integrally formed with the first wall 211, the first surface 2111 is the aforementioned third outer surface 2113.

[0254] Taking the third outer surface 2113 as a rectangle as an example, the center point of the third outer surface 2113 is the intersection of the diagonals of the rectangle. Taking the third outer surface 2113 as a circle as an example, the center point of the third outer surface 2113 is the center of the circle.

[0255] The center point of the third outer surface 2113 can be located at the edge of the projection of the first weak portion 2144 onto the third outer surface 2113. For example, if the first weak portion 2144 is a straight structure, the center point of the third outer surface 2113 can be located at one end of the projection of the first weak portion 2144 onto the third outer surface 2113. Alternatively, the center point of the third outer surface 2113 can be located at the middle of the projection of the first weak portion 2144 onto the third outer surface 2113. For example, if the first weak portion 2144 is a straight structure, the center point of the third outer surface 2113 can be located at the midpoint of the projection of the first weak portion 2144 onto the third outer surface 2113.

[0256] Along the thickness direction of the first wall 211, the projection of the first weak part 2144 covers the center of the third outer surface 2113. The position of the first weak part 2144 is closer to the middle position of the first wall 211 along the first direction, which is more conducive to the first weak part 2144 cracking before the second weak part 2145, so that the predetermined pressure relief area 21431 can be flipped open under the guidance of the second weak part 2145, which is conducive to improving the reliability of the battery cell 20.

[0257] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7In some embodiments, a second weak portion 2145 is provided 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 is a first cross-sectional area, and the cross-sectional area of ​​the second weak portion 2145 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.

[0258] The fourth distance represents the minimum distance between the second weak point 2145 and the first outer surface 2121 along the first direction. Please refer to [reference needed]. Figure 5 The figure shows the fourth distance, which is L3. During measurement, the distance between the position of the second weak part 2145 closest to the first outer surface 2121 and the first outer surface 2121 can be measured. Multiple measurements can be taken and the average value taken to reduce measurement error.

[0259] The fifth distance represents the minimum distance between the second weak point 2145 and the second outer surface 2131. Please refer to [the relevant documentation]. Figure 5 The figure shows the fifth distance, which is L4. During measurement, the distance between the position of the second weak part 2145 closest to the second outer surface 2131 and the second outer surface 2131 can be measured. Multiple measurements can be taken and the average value taken to reduce measurement error.

[0260] The difference between the fifth distance and the fourth distance is the larger of the fifth distance and the smaller of the fourth distance.

[0261] "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." That is, when |L4-L3| / L≥0.4, 0.7<S2 / S1≤1.5. |L4-L3| / L≥0.4 indicates that the distance from the second weak part 2145 to the first outer surface 2121 and the distance from the second weak part 2145 to the second outer surface 2131 are significantly different. In other words, the second weak part 2145 is set off from the middle position of the first wall 211 and is closer to the first outer surface 2121.

[0262] The first weak part 2144 includes at least one weak segment, which is a straight structure. S1 represents the cross-sectional area of ​​the cross section perpendicular to the extension direction 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 cracking; the larger the cross-sectional area of ​​the weak segment perpendicular to its extension direction, the less likely the weak segment is to crack. The smaller the cross-sectional area of ​​the weak segment perpendicular to its extension direction, the more likely the weak segment is to crack.

[0263] The second weak point 2145 can be a straight structure. S2 represents the cross-sectional area of ​​the cross section perpendicular to the extension direction of the second weak point 2145. The cross-sectional area of ​​the second weak point 2145 perpendicular to its extension direction has a significant impact on whether the second weak point 2145 is prone to cracking. The larger the cross-sectional area of ​​the second weak point 2145 perpendicular to its extension direction, the less likely the second weak point 2145 is to crack. The smaller the cross-sectional area of ​​the second weak point 2145 perpendicular to its extension direction, the more likely the second weak point 2145 is to crack.

[0264] By restricting the relationship between S1 and S2, the risk that the second weak part 2145 will crack before the first weak part 2144 when the battery cell 20 is depressurized can be reduced.

[0265] When |L4-L3| / L≥0.4, the values ​​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.

[0266] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with Comparative Examples 1-6 and Embodiments 1-17. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0267] Example 1

[0268] 1) Preparation of positive electrode sheet

[0269] LiNi, the positive electrode active material 0.7 Co 0.1 Mn 0.1A positive electrode slurry is prepared in N-methylpyrrolidone (NMP) using O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF). The solid content of the positive electrode slurry is 50 wt%, and the solid component is 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. After cold pressing, the foil is trimmed, cut, and slit. Then it is dried under vacuum at 85°C for 4 hours to produce the positive electrode sheet.

[0270] 2) Preparation of negative electrode sheet

[0271] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry. The solid content of the negative electrode slurry is 30 wt%, and the mass ratio of graphite, silicon suboxide, Super P, CMC, and binder 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 sheets, and slit. Finally, it is dried under vacuum at 120°C for 12 hours to prepare the negative electrode sheet.

[0272] 3) Preparation of electrolytes

[0273] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), the thoroughly 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 mixed evenly to obtain a liquid electrolyte with a concentration of 1 mol / L.

[0274] 4) Isolation components

[0275] A 16μm polyethylene film was used as the separator.

[0276] 5) Preparation of battery cell 20

[0277] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to isolate them. The electrode assembly 22 is then wound up and placed inside an aluminum casing 21. The electrolyte prepared above is injected into the dried casing 21. The process includes encapsulation, settling, formation, shaping, and capacity testing to complete the preparation of the battery cell 20. A first weak point 2144 and a second weak point 2145 are formed on the first wall 211 of the casing 21 of the battery cell 20. (This is from Example 1.) The outer casing 21 of the battery cell 20 has a cuboid structure. The shell 215 of the outer casing 21 has an opening 2151 at one end. The wall opposite the end cap 216 of the shell 215 is a first wall 211, which is rectangular. The first wall 211 has 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. The first groove 2146 has an "H" shaped structure, that is, the first groove 2146 includes a first groove segment 2143a, a second groove segment 2143b and a third groove segment 2143c. The first groove segment 2143a and the third groove segment 2143c are arranged opposite to each other and both extend along the first direction. The second groove segment 2143b is connected between the first groove segment 2143a and the third groove segment 2143c. The second groove segment 2143b is located in the middle of the first wall 211 in the first direction. The battery cell 20 has a thickness of 39mm, a width of 203mm, a shoulder height (the dimension of the outer casing 21 in the height direction) of 122.7mm, and a capacity of 185Ah.

[0278] The distance L between the first outer surface 2121 and the second outer surface 2131, the minimum distance L3 between the second weak part 2145 and the first outer surface 2121, the minimum distance L4 between the second weak part 2145 and the second outer surface 2131, the width D1 of the bottom surface of the groove segment, the thickness H1 of the weak part, the width D2 of the bottom surface of the second groove 21451, and the thickness H2 of the second weak part 2145 were all obtained by tomographic scanning and then measured by software.

[0279] The preparation methods of the battery cells 20 in Comparative Examples 1-4 and Examples 2-10 are the same as those in Example 1. The difference lies in the difference between the minimum distance L4 between the second weak part 2145 and the second outer surface 2131 and the minimum distance L3 between the second weak part 2145 and the first outer surface 2121, the cross-sectional area S1 of the weak segment perpendicular to its extension direction and the cross-sectional area S2 of the second weak part 2145 perpendicular to its extension direction. In Comparative Examples 1-4 and Examples 1-10, the first direction is the width direction of the first wall 211. The specific details are shown in Tables 1-2.

[0280] The preparation methods of the battery cells 20 in Comparative Examples 5-6 and Examples 11-17 are the same as those in Example 1. The difference lies in the difference between the minimum distance L4 between the second weak part 2145 and the second outer surface 2131 and the minimum distance L3 between the second weak part 2145 and the first outer surface 2121, the cross-sectional area S1 of the weak segment perpendicular to its extension direction and the cross-sectional area S2 of the second weak part 2145 perpendicular to its extension direction. In Comparative Examples 5-6 and Examples 11-17, the first direction is the length direction of the first wall 211, as shown in Table 3.

[0281] Before testing, the battery cell 20 needs to be pretreated: ① Drill a hole at the injection hole of the battery cell 20; ② Insert the tubing into the battery cell 20 10mm from the injection hole; ③ Extrude the AB glue onto the cardboard and stir it evenly; ④ Apply the evenly mixed AB glue around the interface between the tubing and the battery cell 20 (Note: there should be no air bubbles or dirt on the bonding surface), and let it stand for 30 minutes.

[0282] During the explosion experiment, steel clamps are used to clamp the two large surfaces of the battery cell 20 (when the first direction is the width direction 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 constraint state of the battery cell 20 in a real module or battery pack. Simultaneously, the pressure relief component 214 is recorded throughout the experiment to observe its detonation position and the flipping action of the predetermined pressure relief zone 21431. Before the experiment, the detonation pressure testing system is connected to the battery cell 20 via a hose. During the experiment, the detonation pressure testing system inflates the battery cell 20 at 0.3MPa / s for detonation and monitors the inlet pressure of the battery cell 20 in real time. When the inlet pressure drops below 0.02MPa, inflation is stopped. Generally, the inlet pressure curve shows an increasing trend. When the inlet pressure reaches the detonation pressure of the battery cell 20, it suddenly drops to 0. The maximum value of this curve at this point is the detonation pressure of the battery cell 20.

[0283] The experimental results of Comparative Examples 1-6 and Examples 1-17 are shown in Tables 1-3 below:

[0284] Table 1

[0285]

[0286] Table 2

[0287]

[0288] Table 3

[0289]

[0290]

[0291] Please refer to Tables 1 to 2. As shown in Comparative Examples 1 and 3, |L4-L3| / L≥0.4, but S2 / S1≤0.7. At this time, the cross-sectional area of ​​the second weak part 2145 perpendicular to its extension direction is smaller. When the battery cell 20 is depressurized, the second weak part 2145 cracks before the first weak part 2144.

[0292] 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. The stiffness of the first wall 211 at the position of the second weak portion 2145 differs significantly from the stiffness at the position of the first weak portion 2144. Stiffness has a significant impact on the cracking of both the first and second weak portions 2144 and 2145. Furthermore, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is larger, resulting in greater strength of the pressure relief component 214 at the position of the second weak portion 2145. This significantly hinders the opening of the predetermined pressure relief zone 21431, making it difficult for the predetermined pressure relief zone 21431 to open under the action of the fluid medium. In engineering, it is desirable that the detonation position of the pressure relief component 214 is located at the first weak portion 2144, with the second weak portion 2145 serving only a guiding role. When using 20 battery cells in the 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.

[0293] 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 part 2144, but also meets the engineering expectations for the detonation pressure.

[0294] 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 direction. At this point, the second weak portion 2145 is close to the first outer surface 2121. The stiffness of the first wall 211 at the position of the second weak portion 2145 differs significantly from the stiffness at the position of the first weak portion 2144. Stiffness has a significant impact on the cracking of the first and second weak portions 2144 and 2145. If the influence of stiffness on the first and second weak portions 2144 and 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 segment perpendicular to its extension direction, i.e., 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 plays a guiding role in the predetermined pressure relief zone 21431. However, considering that stiffness has a significant impact on the cracking of the first weak part 2144 and the second weak part 2145 (under the same cross-sectional area, the second weak part 2145 is more difficult to crack than the first weak part 2144, therefore, the cross-sectional area of ​​the second weak part 2145 can be set to be smaller), when 0.7 < S2 / S1 ≤ 1, the first weak part 2144 can open and relieve pressure before the second weak part 2145, and the second weak part 2145 plays a guiding role for the predetermined pressure relief area 21431. Similarly, since stiffness has a significant impact on the cracking of the first weak part 2144 and the second weak part 2145, when S2 / S1 ≤ 1.5, the strength of the pressure relief component 214 at the position of the second weak part 2145 is smaller, and the resistance to the opening of the predetermined pressure relief area 21431 is smaller, making it easier for the predetermined pressure relief area 21431 to open under the action of the fluid medium.

[0295] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the first wall 211 has a third outer surface 2113 that is away from the interior of the outer shell 21. The third outer surface 2113 is rectangular, and a first direction is parallel to the width direction of the rectangle.

[0296] "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.

[0297] 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. 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.

[0298] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 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 weak portion 2144 in the region where the first groove 2146 is provided, and a second weak portion 2145 in the region where the second groove 21451 is provided. The first groove 2146 includes at least one groove segment. The pressure relief component 214 forms a weak segment in the region where the groove segment is provided. The cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area. The minimum width of the bottom surface of the groove segment is a first width. 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 portion 2145 perpendicular to its extension direction is a second cross-sectional area. The minimum width of the bottom surface of the second groove 21451 is a second width. The minimum thickness of the second weak portion 2145 is a second thickness. 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.

[0299] "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," which means h2≥h1 and a2≤a1.

[0300] 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 part 2145 better guide the predetermined pressure relief area 21431 to open, but also, 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 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, the second width is minimized, thereby reducing the area occupied by the second groove 21451 on the third outer surface 2113 of the pressure relief component 214.

[0301] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7In some embodiments, a second weak portion 2145 is provided 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 is a first cross-sectional area, and the cross-sectional area of ​​the second weak portion 2145 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.

[0302] "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.

[0303] When |L4-L3| / L<0.4, the values ​​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.

[0304] Referring to Table 3, as shown in Comparative Example 5, |L4-L3| / L<0.4, S2 / S1≤1.5. In this case, the second weak portion 2145 is close to the middle of the first outer surface 2121. The stiffness of the first wall 211 at the position of the second weak portion 2145 is similar to that at the position of the first weak portion 2144. Therefore, the stiffness has a relatively small impact on the cracking of the first and second weak portions 2144 and 2145. However, at this time, 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 will crack before the first weak portion 2144.

[0305] Referring to Table 3, as shown in Comparative Example 6, |L4-L3| / L < 0.4, S2 / S1 > 5. At this point, the second weak point 2145 is close to the middle of the first outer surface 2121. The stiffness of the first wall 211 at the position of the second weak point 2145 is similar to that at the position of the first weak point 2144, and the stiffness has a relatively small impact on the cracking of the first and second weak points 2144 and 2145. However, at this point, the cross-sectional area of ​​the second weak point 2145 perpendicular to its extension direction is too large, and the strength of the pressure relief component 214 at the position of the second weak point 2145 is too great, resulting in significant resistance to the opening of the predetermined pressure relief zone 21431. This makes it difficult for the predetermined pressure relief zone 21431 to open under the action of the fluid medium. In engineering, it is desirable that the detonation position of the pressure relief component 214 is located at the first weak point 2144, with the second weak point 2145 serving only a guiding role. When using battery cell 20 in the 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.

[0306] 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 part 2144, but also meets the engineering expectations for the detonation pressure.

[0307] When |L4-L3| / L < 0.4, the distance between the second weak portion 2145 and the center position of the first wall 211 along the first direction is small. At this time, the second weak portion 2145 is also relatively close to the center position of the first wall 211 along the first direction. The stiffness of the first wall 211 at the position of the second weak portion 2145 is similar to that at the position of the first weak portion 2144. Therefore, the stiffness has little impact on the cracking of the first weak portion 2144 and the second weak portion 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 plays a guiding role in the predetermined pressure relief zone 21431, reducing the risk that the second weak portion 2145 will crack before the first weak portion 2144. When S2 / S1≤5, the strength of the pressure relief component 214 at the second weak part 2145 is relatively small, which reduces 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 action of the fluid medium.

[0308] Please refer to Figure 8 , Figure 8This is a bottom view of the casing 21 of a battery cell 20 provided in some embodiments of this application. In some embodiments, the first wall 211 has a third outer surface 2113 facing away from the interior of the casing 21. The third outer surface 2113 is rectangular, and a first direction is parallel to the length direction of the rectangle.

[0309] "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.

[0310] The first weak part 2144 and the second weak part 2145 are arranged along the length direction of the third outer surface 2113. The first weak part 2144 and the second weak part 2145 are both closer to the middle position of the first wall 211 along the length direction, and the stiffness has a smaller impact on the cracking of the first weak part 2144 and the second weak part 2145.

[0311] In some embodiments, 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.

[0312] "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", which means that when |L4-L3| / L<0.4, 2.13≤S2 / S1≤4.67.

[0313] When |L4-L3| / L<0.4, the values ​​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.

[0314] Please refer to Table 3. As shown in Examples 13 to 15, |L4-L3| / L<0.4, 2.13≤S2 / S1≤4.67, which not only enables the detonation position of the pressure relief component 214 to be located at the first weak part 2144, but also makes the detonation pressure closer to 0.9MPa.

[0315] When S2 / S1≥2.13, the first weak part 2144 is more likely to open and release pressure before the second weak part 2145. The second weak part 2145 plays a guiding role in the predetermined pressure relief area 21431, further reducing the risk that the second weak part 2145 will crack before the first weak part 2144. When S2 / S1≤4.67, the pressure relief component 214 has less strength at the position of the second weak part 2145, and there is less resistance to the opening of the predetermined pressure relief area 21431, making it easier for the predetermined pressure relief area 21431 to open under the action of the fluid medium.

[0316] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 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 weak portion 2144 in the region where the first groove 2146 is provided, and a second weak portion 2145 in the region where the second groove 21451 is provided. The first groove 2146 includes at least one groove segment. The pressure relief component 214 forms a weak segment in the region where the groove segment is provided. The cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area. The minimum width of the 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 portion 2145 perpendicular to its extension direction is a second cross-sectional area. The minimum width of the bottom surface of the second groove 21451 is a second width, and the minimum thickness of the second weak portion 2145 is a second thickness. 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.

[0317] "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," which means h2≥h1 and a2≥a1.

[0318] 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 stiffness variations in different regions of the first wall 211 on the cracking of the weak section and the second weak section 2145 can be further reduced. This allows the weak section to crack when the battery cell 20 is depressurized, while the second weak section 2145 guides the flipping of the predetermined depressurization area 21431. In some embodiments, the first cross-sectional area is S1, satisfying: 0.0002 mm. 2 ≤S1≤0.8mm 2 .

[0319] The cross-sectional area of ​​the weak section perpendicular to its extension direction can be taken as: 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 0.15mm2 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 wait.

[0320] When S1 ≥ 0.0002 mm 2 When the first weakest segment has a larger cross-sectional area perpendicular to its extension direction, it is less prone to cracking under external impact, which helps improve the reliability of the battery cell 20. When S1 ≤ 0.8mm 2 At this time, the cross-sectional area of ​​the first weak section perpendicular to its extension direction will not be too large. When the internal pressure of the battery cell 20 reaches the explosion pressure, the first weak section is easily broken under the action of the fluid medium to achieve pressure relief. Therefore, when 0.0002mm 2 ≤S1≤0.8mm 2 It can both resist external impacts and easily open for pressure relief when the internal pressure of the battery cell 20 reaches the explosion pressure.

[0321] Optionally, 0.002mm 2 ≤S1≤0.3mm 2 .

[0322] The cross-sectional area of ​​the weak section perpendicular to its extension direction can be taken as: 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 0.25mm2 0.28mm 2 0.3mm 2 wait.

[0323] When S1 ≥ 0.002 mm 2 This can further reduce the risk of the first weak segment cracking under external impact, which is beneficial to improving the reliability of the battery cell 20. When S1 ≤ 0.3mm 2 When the internal pressure of the battery cell 20 reaches the explosion pressure, the first weakest section is more likely to crack under the action of the fluid medium, thus achieving pressure relief. Therefore, when 0.002mm 2 ≤S1≤0.3mm 2 At the same time, it can better resist external impacts and is easy to open for pressure relief when the internal pressure of the battery cell 20 reaches the explosion pressure.

[0324] Optionally, 0.008mm 2 ≤S1≤0.12mm 2 .

[0325] The cross-sectional area of ​​the weak section perpendicular to its extension direction can be taken as: 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.

[0326] When S1≥0.008mm 2 This can further reduce the risk of the first weak segment cracking under external impact, which is beneficial to improving the reliability of the battery cell 20. When S1 ≤ 0.12mm2 When the internal pressure of the battery cell 20 reaches the explosion pressure, the first weakest section is more likely to crack under the action of the fluid medium, thus achieving pressure relief. Therefore, when 0.008mm 2 ≤S1≤0.12mm 2 At the same time, it can better resist external impacts and is easy to open for pressure relief when the internal pressure of the battery cell 20 reaches the explosion pressure.

[0327] In some embodiments, the second cross-sectional area is S2, satisfying: 0.001 mm 2 ≤S2≤1mm 2 .

[0328] The cross-sectional area of ​​the second weak point 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 0.15mm 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 0.85mm 2 0.9mm 2 0.95mm 2 1mm 2 wait.

[0329] When S2 ≥ 0.001 mm 2 When the second weak point 2145 has a larger cross-sectional area perpendicular to its extension direction, it is less prone to cracking under external impact, which helps improve the reliability of the battery cell 20. When S2 ≤ 1mm 2At this time, the cross-sectional area of ​​the second weak part 2145 perpendicular to its extension direction will not be too large, thereby helping to reduce the resistance to the flipping of the predetermined pressure relief zone 21431 and facilitating the rapid flipping and opening of the predetermined pressure relief zone 21431. Therefore, when 0.001mm 2 ≤S2≤1mm 2 It can both resist external impacts and facilitate the quick flipping and opening of the predetermined pressure relief zone 21431.

[0330] In some embodiments, 0.008mm 2 ≤S2≤0.45mm 2 .

[0331] The cross-sectional area of ​​the second weak point 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 0.25mm 2 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.

[0332] When S2 ≥ 0.008 mm 2 This further reduces the risk of the second weak point 2145 cracking under external impact, which is beneficial to improving the reliability of the battery cell 20. When S2 ≤ 0.45mm 2 The resistance to the flipping of the predetermined pressure relief zone 21431 is smaller, making it easier for the predetermined pressure relief zone 21431 to flip and open quickly. Therefore, when 0.008mm 2 ≤S2≤0.45mm 2 At the same time, it can better resist external impacts and facilitates the quick flipping and opening of the predetermined pressure relief zone 21431.

[0333] Optionally, 0.03mm 2≤S2≤0.15mm 2 .

[0334] The cross-sectional area of ​​the second weak point 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 0.14mm 2 0.145mm 2 0.15mm 2 wait.

[0335] When S2 ≥ 0.03 mm 2 This further reduces the risk of the second weak point 2145 cracking under external impact, which is beneficial to improving the reliability of the battery cell 20. When S2 ≤ 0.15mm 2 The resistance to the flipping of the predetermined pressure relief zone 21431 is smaller, making it easier for the predetermined pressure relief zone 21431 to flip and open quickly. Therefore, when 0.03mm 2 ≤S2≤0.15mm 2 At the same time, it can better resist external impacts and facilitates the rapid flipping and opening of the predetermined pressure relief zone 21431. Please refer to... Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the pressure relief component 214 is provided with a second groove 21451, and a second weak portion 2145 is formed in the area where the second groove 21451 is provided. The second groove 21451 is provided on the surface of the pressure relief component 214 facing the interior of the housing 21.

[0336] Along the thickness direction of the first wall 211, the pressure relief component 214 has a first surface 2111 and a second surface 2112 disposed opposite to each other, wherein the first surface 2111 faces away from the interior of the outer casing 21, and the second surface 2112 faces the interior of the outer casing 21. A second groove 21451 is disposed on the second surface 2112.

[0337] The second groove 21451 can be formed by various methods, such as stamping or cold heading. Taking the stamping method for forming the second groove 21451 as an example, 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.

[0338] By using stamping or cold forging to form the second groove 21451, the groove wall of the second groove 21451 undergoes work hardening (the grain arrangement changes, leading to lattice distortion, reducing the metal's plasticity, and increasing the material's hardness), thus enhancing its resistance to external impacts and making it less susceptible to damage from external impacts. This helps reduce the risk of leakage from the pressure relief component 214.

[0339] The second weak point 2145 is formed by creating a second groove 21451 on the pressure relief component 214, which is simple, convenient, and low in cost. In addition, by setting the second groove 21451 on the surface of the pressure relief component 214 facing the inside of the outer casing 21, the tension that the predetermined pressure relief area 21431 needs to overcome when flipping is smaller, which facilitates the quick flipping and opening of the predetermined pressure relief area 21431 and helps to improve the reliability of the battery cell 20.

[0340] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the pressure relief component 214 has a first surface 2111 and a second surface 2112 disposed opposite to 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 weak 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 weak portion 2145 in the region where the second groove 21451 is provided.

[0341] The first groove 2146 is disposed on the first surface 2111, and the second groove 21451 is disposed 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 disposed opposite to each other along the thickness direction of the first wall 211.

[0342] Along the thickness direction of the first wall 211, the first weak portion 2144 is the part of the pressure relief component 214 located between the bottom surface of the first groove 2146 furthest from the first surface 2111 and the second surface 2112. The second weak portion 2145 is the part of the pressure relief component 214 located between the bottom surface of the second groove 21451 furthest from the second surface 2112 and the first surface 2111.

[0343] The first groove 2146 can be formed by various methods, such as stamping or cold heading. Taking the stamping method as an example, 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.

[0344] By using stamping or cold forging to form the first groove 2146, the groove wall of the first groove 2146 undergoes work hardening (the grain arrangement changes, leading to lattice distortion, reducing the metal's plasticity, and increasing the material's hardness), thus enhancing its resistance to external impacts and making it less susceptible to damage from external impacts. This helps reduce the risk of leakage from the pressure relief component 214.

[0345] The first weak portion 2144 and the second weak portion 2145 are formed by creating a first groove 2146 and a second groove 21451 on the pressure relief component 214, which is simple, convenient, and low in cost. By setting the first groove 2146 and the second groove 21451 on the first surface 2111 and the second surface 2112 of the pressure relief component 214 respectively, so that the first groove 2146 and the second groove 21451 are located on both sides of the pressure relief component 214, it is convenient to process the first groove 2146 and the second groove 21451 on both sides of the pressure relief component 214 respectively, which helps to reduce the mutual influence between the first groove 2146 and the second groove 21451 during the processing.

[0346] Optionally, the first surface 2111 is the surface of the pressure relief component 214 facing away from the inside of the housing 21, and the second surface 2112 is the surface of the pressure relief component 214 facing the inside of the housing 21.

[0347] The first surface 2111 is the surface of the pressure relief component 214 that faces away from the inside of the outer casing 21, that is, the outer surface of the pressure relief component 214, which is also the aforementioned third outer surface 2113. The second surface 2112 is the surface of the pressure relief component 214 that faces the inside of the outer casing 21, that is, the inner surface of the pressure relief component 214.

[0348] The first groove 2146 is provided on the outer surface of the pressure relief component 214, and the second groove 21451 is provided on the inner surface of the pressure relief component 214.

[0349] By providing the first groove 2146 on the surface of the pressure relief component 214 facing away from the inside of the outer casing 21, the tension that the first weak part 2144 needs to overcome when cracking is smaller, making it easier to crack. By providing the second groove 21451 on the surface of the pressure relief component 214 facing the inside of the outer casing 21, the tension that the predetermined pressure relief area 21431 needs to overcome when flipping is smaller, thereby facilitating the rapid flipping and opening of the predetermined pressure relief area 21431, which helps to improve the reliability of the battery cell 20.

[0350] Please refer to Figure 9 , Figure 9 This is a bottom view of the casing 21 of a battery cell 20 according to some embodiments of this application. In some embodiments, a pressure relief component 214 is provided with a first groove 2146, and the pressure relief component 214 forms a first weak portion 2144 in the region where the first groove 2146 is provided. The first groove 2146 includes a first groove segment 2143a and a second groove segment 2143b, which are connected. The pressure relief component 214 forms a weak segment in the region where the first groove segment 2143a and the second groove segment 2143b are provided. The two weak segments together define a predetermined pressure relief area 21431.

[0351] The line connecting the free end of the first groove segment 2143a and the free end of the second groove segment 2143b is the first connecting line. The closed area enclosed by the weak segment corresponding to the first groove segment 2143a, the weak segment corresponding to the second groove segment 2143b, and the first connecting line is the predetermined pressure relief zone 21431.

[0352] The bottom of the first tank segment 2143a and the second tank segment 2143b each has a weak segment, and the two weak segments together define a predetermined pressure relief area 21431. The first tank segment 2143a and the second tank segment 2143b are arranged along the edge of the predetermined pressure relief area 21431, so that when the battery cell 20 is depressurized, the two weak segments can crack along the edge of the predetermined pressure relief area 21431.

[0353] For example, in Figure 9 In the middle, one end of the first groove segment 2143a and one end of the second groove segment 2143b are connected to form an "L"-shaped first groove 2146. Please refer to... Figure 9 The first connecting line connects the two ends of the L-shaped structure. Of course, in other embodiments, one end of the second groove segment 2143b can also be connected to the middle position of the first groove segment 2143a, so that the pressure relief component 214 forms a predetermined pressure relief area 21431 on both sides of the second groove segment 2143b.

[0354] The first segment 2143a and the second segment 2143b are interconnected, so that the first segment 2143a and the second segment 2143b together define the predetermined pressure relief area 21431. On the one hand, this can increase the pressure relief area of ​​the battery cell 20 and improve the pressure relief rate of the battery cell 20. On the other hand, it makes the connection between the first segment 2143a and the second segment 2143b weaker, making it easier to crack and open the predetermined pressure relief area 21431 to release the internal pressure of the battery cell 20.

[0355] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the pressure relief component 214 is provided with a first groove 2146, and the pressure relief component 214 forms a first weak portion 2144 in the area where the first groove 2146 is provided. The first groove 2146 includes a first groove segment 2143a, a second groove segment 2143b, and a third groove segment 2143c. The first groove segment 2143a and the third groove segment 2143c are disposed opposite to each other, and the second groove segment 2143b connects the first groove segment 2143a and the third groove segment 2143c. The pressure relief component 214 forms a weak segment in the area where the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c are provided, and the three weak segments together define a predetermined pressure relief area 21431.

[0356] The first slot segment 2143a and the third slot segment 2143c are spaced apart and at least partially opposite each other. Optionally, both the first slot segment 2143a and the third slot segment 2143c extend along a first direction.

[0357] 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.

[0358] The bottom of the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c each has a weak section, and the three weak sections together define the predetermined pressure relief zone 21431. Please refer to... Figure 5The line connecting the free end of the first slot segment 2143a and the free end of the second slot segment 2143b is the first connecting line, which is positioned opposite to the second slot segment 2143b along a first direction. The closed area enclosed by the weak segment corresponding to the first slot segment 2143a, the weak segment corresponding to the second slot segment 2143b, the weak segment corresponding to the third slot segment 2143c, and the first connecting line is the predetermined pressure relief zone 21431. In other words, the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c are 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 segment 2143a, the second groove segment 2143b, and the third groove segment 2143c as the boundary. That is, the predetermined pressure relief area 21431 is formed within the area enclosed by the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 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 segment 2143a, the second groove segment 2143b, and the third groove segment 2143c as the boundary when the battery cell 20 is depressurized, thereby releasing the internal pressure of the battery cell 20.

[0359] Reference Figure 10 , Figure 10 This is a bottom view of the casing 21 of the battery cell 20 provided in other embodiments of this application. 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 can be a "U" shape, that is, one end of the second groove segment 2143b is connected to one end of the first groove segment 2143a, and the other end is connected to one end of the third groove segment 2143c, so as to form a predetermined pressure relief area 21431 on the pressure relief component 214. At this time, the first connecting line closes the opening end of the U-shaped structure.

[0360] The first groove 2146 includes a first groove segment 2143a, a second groove segment 2143b, and a third groove segment 2143c. The second groove segment 2143b connects the first groove segment 2143a and the third groove segment 2143c, so that the pressure relief component 214 can crack along the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c when the battery cell 20 is depressurized, 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 of the first groove segment 2143a and the second groove segment 2143b, as well as the connection position of the first groove segment 2143a and the third groove segment 2143c, weaker, easier to crack 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.

[0361] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the first weak portion 2144 defines two predetermined pressure relief zones 21431, which are located on opposite sides of the second groove segment 2143b. Each predetermined pressure relief zone 21431 is provided with at least one second weak portion 2145.

[0362] See Figure 5 As shown, the first groove 2146 formed by the first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c can be 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.

[0363] Each predetermined pressure relief zone 21431 may be provided with one, two, three, or more second weak points 2145. See Figure 5 As shown, each predetermined pressure relief zone 21431 is provided with a corresponding second weak point 2145.

[0364] The first weak portion 2144 defines two predetermined pressure relief areas 21431. Each predetermined pressure relief area 21431 is provided with at least one second weak portion 2145. When the battery cell 20 is depressurized, 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.

[0365] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, each predetermined pressure relief zone 21431 is provided with a corresponding second weak portion 2145, and the pressure relief component 214 is provided with a second groove 21451, forming a second weak portion 2145 in the area where the second groove 21451 is provided. A first groove 2146 is located between the two second grooves 21451.

[0366] The pressure relief component 214 forms a second weak portion 2145 in the area where the second groove 21451 is provided, and each predetermined pressure relief area 21431 is provided with a corresponding second groove 21451. Along the first direction, the two second grooves 21451 are located on both sides of the second groove segment 2143b.

[0367] See Figure 5As shown, 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 segment 2143a, the second groove segment 2143b and the third groove segment 2143c are all located between the two second grooves 21451.

[0368] The predetermined pressure relief area 21431 corresponds one-to-one with the second weak portion 2145, which reduces the number of second weak portions 2145 required, reduces the number of processing steps for the pressure relief component 214, and reduces 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 is depressurized, the pressure relief component 214 can split along the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c, thereby opening the two predetermined pressure relief areas 21431. These areas 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. This improves the pressure relief rate of the battery cell 20 and enhances its reliability.

[0369] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the position where the second slot segment 2143b is connected to the first slot segment 2143a is offset from both ends of the first slot segment 2143a, and the position where the second slot segment 2143b is connected to the third slot segment 2143c is offset from both ends of the third slot segment 2143c.

[0370] The connection position between the second groove segment 2143b and the first groove segment 2143a is offset from both ends of the first groove segment 2143a. In other words, the second groove segment 2143b is connected between the two ends of the first groove segment 2143a. Similarly, the connection position between the third groove segment 2143c and the second groove segment 2143b is offset from both ends of the third groove segment 2143c. In other words, 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 approximately "H" shaped.

[0371] By setting the connection position between the second groove segment 2143b and the first groove segment 2143a to be located between the two ends of the second groove segment 2143b, and setting the connection position between the second groove segment 2143b and the third groove segment 2143c to be located between the two ends of the third groove segment 2143c, the first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c form an H-shaped structure, so that both sides of the second groove segment 2143b of the first groove 2146 can form a predetermined pressure relief area 21431, and the two predetermined pressure relief areas 21431 can open in a split manner to relieve pressure when the battery cell 20 is depressurized, 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.

[0372] In some embodiments, please continue to see Figure 5 As shown, the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c all extend along a straight trajectory, and the first groove segment 2143a and the third groove segment 2143c are both perpendicular to the second groove segment 2143b. That is, the extension direction of the second groove segment 2143b is perpendicular to the extension direction of the first groove segment 2143a and the extension direction 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 "H" shaped structure, and two predetermined pressure relief zones 21431 are formed on both sides of the second groove segment 2143b. Of course, the areas of the two predetermined pressure relief zones 21431 can be the same or different.

[0373] By setting the first groove segment 2143a and the third groove segment 2143c to be perpendicular to the second groove segment 2143b, the extension direction of the second groove segment 2143b is the arrangement direction of the first groove segment 2143a and the third groove segment 2143c. On the one hand, this can improve the regularity of the shape of the first groove 2146, which is conducive to reducing the processing difficulty of the first groove 2146 and thus reducing the manufacturing cost of the battery cell 20. On the other hand, it facilitates the two predetermined pressure relief areas 21431 on both sides of the second groove segment 2143b on the pressure relief component 214 to relieve pressure in an open direction when the battery cell 20 is depressurized.

[0374] According to some embodiments of this application, refer to Figure 11 , Figure 11 The following is a bottom view of the casing 21 of the battery cell 20 provided in some embodiments of this application. The first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c all extend along an arc trajectory.

[0375] For example, in Figure 11In this design, the two ends of the second groove segment 2143b are respectively connected to one end of the first groove segment 2143a and one end of the third groove segment 2143c, and the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c all extend along an arc trajectory, so that the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c form a first groove 2146 with a "C"-shaped structure. At this time, the first connecting line closes the open end of the C-shape.

[0376] By setting the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c to extend along an arc trajectory, it is beneficial to improve the curvature of the connection position between the first groove segment 2143a and the second groove segment 2143b, and also to improve the curvature of the connection position between the second groove segment 2143b and the third groove segment 2143c. On the one hand, this reduces the processing difficulty of the first groove 2146, and on the other hand, it facilitates the pressure relief component 214 to open the predetermined pressure relief area 21431 to release the internal pressure of the battery cell 20 after it splits along the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c.

[0377] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the pressure relief component 214 is provided with a second groove 21451, and the pressure relief component 214 forms a second weak portion 2145 in the area where the second groove 21451 is provided. The first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c are all spaced apart from the second groove 21451.

[0378] The first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c are all spaced apart from the second groove 21451, and the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c do not contact the second groove 21451.

[0379] By arranging the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c at intervals from the second groove 21451, 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 it cracks along the first groove 2146 to relieve pressure can be reduced. Furthermore, the stress influence between the area of ​​the pressure relief component 214 where the first groove 2146 is located and the area of ​​the pressure relief component 214 where the second groove 21451 is located can be reduced.

[0380] In some embodiments, the second groove segment 2143b and the second groove 21451 are disposed opposite to each other along a first direction, and along the first direction, the first groove segment 2143a and the third groove segment 2143c are both disposed at intervals from the second groove 21451.

[0381] Along the first direction, the second groove segment 2143b is disposed opposite to the second recess 21451, and the first groove segment 2143a and the third groove segment 2143c are both disposed at intervals from the second recess 21451. The first groove segment 2143a and the second recess 21451 are separated by a distance in the direction in which the second groove segment 2143b and the second recess 21451 are disposed opposite to each other. The third groove segment 2143c and the second recess 21451 are also separated by a distance in the direction in which the second groove segment 2143b and the second recess 21451 are disposed opposite to each other.

[0382] By arranging the second groove segment 2143b and the second groove 21451 opposite each other in the first direction, and by arranging the first groove segment 2143a and the third groove segment 2143c at intervals from the second groove 21451 in the first direction, the predetermined pressure relief area 21431 defined by the first groove segment 2143a, the second groove segment 2143b and the third groove segment 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 angle at which the predetermined pressure relief area 21431 is flipped after it is opened can be increased, thereby increasing the pressure relief area of ​​the battery cell 20.

[0383] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the first wall 211 has a third outer surface 2113 facing away from the interior of the outer casing 21, and the third outer surface 2113 is rectangular. A first direction is parallel to the length or width direction of the rectangle.

[0384] The second groove segment 2143b and the second recess 21451 are arranged along the length or width direction of the third outer surface 2113. Along the length or width direction of the third outer surface 2113, the first groove segment 2143a and the third groove segment 2143c are spaced apart from the second recess 21451. The third outer surface 2113 has a relatively large space in its length or width direction, making it easier to process the first recess 2146 and the second recess 21451. Furthermore, during production, the detonation pressure of the multiple battery cells 20 produced is relatively consistent.

[0385] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7In some embodiments, the pressure relief component 214 has a first surface 2111 and a second surface 2112 disposed opposite to each other in the thickness direction of the first wall 211. The pressure relief component 214 is provided with a first groove 2146, which is a multi-level groove arranged sequentially along the direction from the first surface 2111 to the second surface 2112. In two adjacent levels of grooves, the first-level groove furthest from the first surface 2111 is disposed on the bottom surface of the first-level groove closest to the first surface 2111. The bottom wall of the first-level groove furthest from the first surface 2111 in the multi-level groove is the first weak part 2144.

[0386] The pressure relief component 214 is provided with multiple levels of grooves, which are sequentially arranged along the direction from the first surface 2111 to the second surface 2112. The contour of the bottom surface of the grooves decreases progressively. 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 or cold heading.

[0387] The bottom wall of the first-level groove, which is furthest from the first surface 2111 in the multi-level groove, is the first weak part 2144. That is, the part of the pressure relief component 214 located between the bottom surface of the first groove 2146 furthest from the first surface 2111 and the second surface 2112 is the first weak part 2144.

[0388] For example, such as Figure 6 and Figure 7 As shown, the pressure relief component 214 is provided with three levels of grooves: a first-level groove 2141, a second-level groove 2142, and a third-level groove 2143. During processing, the first-level groove 2141 can be stamped onto the first surface 2111 firstly, then the second-level groove 2142 can be stamped onto the bottom surface of the first-level groove 2141, and finally the third-level groove 2143 can be stamped onto the bottom surface of the second-level groove 2142. At this point, the bottom wall of the third-level groove 2143 is the first weak point 2144, meaning that the portion of the pressure relief component 214 located between the bottom surface of the third-level groove 2143 and the second surface 2112 is the first weak point 2144.

[0389] like Figure 5 , Figure 6 and Figure 7 As shown, the third-level groove 2143 includes the first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c mentioned above.

[0390] 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 the molding process, multi-level grooves can be sequentially formed on the pressure relief component 214 along the direction from the first surface 2111 to the second surface 2112.

[0391] 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 formed step by step, thereby reducing the molding force on the pressure relief component 214, reducing the risk of cracking, and making the pressure relief component 214 less prone to failure due to cracks at the groove locations, thus improving the reliability of the battery cell 20. When forming the multi-level grooves, stamping or cold forging can be used, which causes work hardening of the groove walls (changing the grain arrangement, leading to lattice distortion, reducing metal plasticity, and increasing material hardness), enhancing its resistance to external impacts and making it less susceptible to damage from external impacts. This helps reduce the risk of leakage from the pressure relief component 214.

[0392] 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.

[0393] 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.

[0394] F / N can take any one of the following point values ​​or a range between any two: 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.

[0395] It is understandable that if the pressure relief component 214 is integrally formed with the first wall 211, 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.

[0396] In this embodiment, 0.16≤F / N<1 ensures that the maximum depth of the first groove 2146 is not too small in proportion to the thickness of the pressure relief component 214, thus preventing the burst pressure of the battery cell 20 from being too high and improving the timeliness of pressure relief of the battery cell 20.

[0397] In some embodiments, 0.4mm≤F≤2mm, 0.8mm≤N≤2.5mm.

[0398] F can take any one of the following values ​​or a range between any two: 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.

[0399] N can take any one of the following values ​​or a range between any two: 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.

[0400] In this embodiment, 0.4mm≤F≤2mm and 0.8mm≤N≤2.5mm ensure that the maximum depth of the first groove 2146 and the thickness of the pressure relief component 214 are within a reasonable range, resulting in better economic efficiency. In the embodiment where the first wall 211 serves as the pressure relief component 214, the thickness of the first wall 211 is 0.8mm to 2.5mm. A thickness greater than or equal to 0.8mm provides sufficient strength, while a thickness less than or equal to 2mm prevents excessive thickness. This allows for an increase in the internal space of the outer shell 21, freeing up more space for the electrode assembly 22, given a fixed volume of the outer shell 21. By controlling the thickness of the first wall 211 within the range of 0.8mm to 2.5mm, and controlling the maximum groove depth of the first groove 2146 within the range of 0.4mm to 2mm, the maximum groove depth of the first groove 2146 is better matched with the thickness of the pressure relief component 214, resulting in good pressure relief capability for the pressure relief component 214.

[0401] In some embodiments, the pressure relief component 214 is integrally formed with the first wall 211.

[0402] One-piece molding means that the first wall 211 and the pressure relief component 214 are provided as a single structure. For example, the pressure relief component 214 can be formed on the first wall 211 by means of stamping or cold forging.

[0403] The pressure relief component 214 is integrally formed with the first wall 211, eliminating the need for additional welding or bonding processes, which helps reduce the risk of leakage from the pressure relief component 214. Furthermore, during production, it is easier to ensure that the detonation pressure of the multiple battery cells 20 produced is more consistent.

[0404] According to some embodiments of this application, the material of the first wall 211 includes steel.

[0405] For example, the material of the first wall 211 can be carbon steel, alloy steel or stainless steel, etc.

[0406] It should be noted that the material of the first wall 211 includes steel. If the first wall 211 is the end cap 216 of the outer shell 21, then the material of the end cap 216 is steel; if the first wall 211 is a wall in the shell 215, then the material of the shell 215 is steel.

[0407] In this embodiment, by setting the material of the first wall 211 to steel, since steel has high strength, the first wall 211 made of steel has better strength, so that the first wall 211 can be made thinner under the condition that the burst pressure of the battery cell 20 is constant, which is beneficial to saving the space occupied by the first wall 211.

[0408] In some embodiments, the steel material is carbon steel or stainless steel.

[0409] For example, carbon steel can be low-carbon steel, medium-carbon steel, or high-carbon steel.

[0410] In this embodiment, carbon steel or stainless steel is used as the material for the first wall 211, which is low in cost and easy to manufacture.

[0411] In some embodiments, the pressure relief component 214 is made of aluminum alloy.

[0412] 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 aluminum alloy. If the first wall 211 is an end cap 216, the end cap 216 can be made of aluminum alloy; if the first wall 211 is a wall portion in the housing 215, then the housing 215 can be made of aluminum alloy.

[0413] Aluminum alloys are lightweight and have good ductility, making it easier to machine 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 forming difficulty of the first wall 211.

[0414] In some embodiments, the aluminum alloy comprises the following components in weight 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%.

[0415] This aluminum alloy belongs to the tri-series aluminum alloy, which has lower hardness and better formability, reducing the processing difficulty of the first groove 2146 and the second groove 21451, which is conducive to improving the processing accuracy of the first groove 2146 and the second groove 21451, and improving the pressure relief consistency of the pressure relief component 214.

[0416] In some embodiments, the aluminum alloy comprises the following components by mass percentage: aluminum ≥ 96.7%, copper ≤ 0.05% ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other individual element components ≤ 0.05%, and other element total components ≤ 0.15%.

[0417] This aluminum alloy belongs to the five-series aluminum. Pressure relief components made from this aluminum alloy, 214, have higher hardness, greater strength, and better resistance to damage.

[0418] In some other embodiments, the pressure relief component 214 is separately disposed 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.

[0419] The phrase "pressure relief component 214 and first wall 211 are separately configured, first wall 211 is provided with a pressure relief hole, and pressure relief component 214 is installed on first wall 211 and covers the pressure relief hole" means that during manufacturing, a pressure relief hole is provided on 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 an explosion-proof plate installed on first wall 211.

[0420] The pressure relief component 214 is separately disposed from the first wall 211 and installed on the first wall 211 to facilitate processing and manufacturing.

[0421] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the battery cell 20 includes an electrode assembly 22, which is housed within a housing 21. A first wall 211 supports the electrode assembly 22 along the direction of gravity.

[0422] The first wall 211 is a wall on the outer casing 21 that supports the electrode assembly 22 along the direction of gravity. Understandably, the first wall 211 can be the bottom wall of the casing 215. The first wall 211 can also be an end cap 216. When the first wall 211 is an end cap 216, it represents a scenario where the battery cell 20 is used inverted.

[0423] The first wall 211 supports the electrode assembly 22 along the direction of gravity, and the pressure relief component 214 is disposed on the first wall 211. In this way, when the battery cell 20 is depressurized, the ejected fluid medium is less likely to act on other electrical connection components, thereby reducing the risk of short circuit when the battery cell 20 is depressurized.

[0424] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the battery cell 20 includes an electrode terminal 23 disposed on the other walls of the housing 21 other than the first wall 211.

[0425] The electrode terminal 23 and the pressure relief component 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 the side wall or end cap 216 of the housing 215. Similarly, when the first wall 211 is one side wall of the housing 215, the electrode terminal 23 can be disposed on other side walls, 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 the side wall or the bottom wall of the housing 215.

[0426] The electrode terminals 23 and the pressure relief component 214 are respectively disposed on different walls of the housing 21. When the battery cell 20 is depressurized, the ejected fluid medium is less likely to act on the electrode terminals 23 and cause the electrode terminals 23 to short-circuit, thus reducing the risk of short circuit when the battery cell 20 is depressurized.

[0427] Optionally, electrode terminals 23 are disposed on the wall of housing 21 opposite to the first wall 211.

[0428] 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 another side wall of the housing 215 opposite to 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.

[0429] The electrode terminal 23 is disposed on the wall of the housing 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, which further reduces the risk of short circuit when the battery cell 20 is depressurized.

[0430] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 In some embodiments, the housing 21 includes a housing 215 and an end cap 216. The housing 215 has an opening 2151, and the end cap 216 is connected to the housing 215 and closes the opening 2151. The end cap 216 is a first wall 211, or the housing 215 includes a first wall 211.

[0431] The housing 215 includes integrally formed side walls and bottom walls, meaning that the housing 215 is manufactured using an integral forming process, such as stamping, casting, or extrusion molding. In other words, the side walls and bottom walls of the housing 215 are an integral structure.

[0432] The housing 215 includes a first wall 211, that is, the first wall 211 is a wall of the housing 215. For example, in... Figure 5 and Figure 6 In this embodiment, the first wall 211 is the bottom wall of the housing 215, which is disposed opposite to 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.

[0433] It should be noted that the structure of the battery cell 20 is not limited to this. In some embodiments, the battery cell 20 can also have other structures. For example, the outer casing 21 can include a housing 215 and an end cap 216. The housing 215 forms a receiving cavity with an opening 2151 inside, which is used to receive the electrode assembly 22. The end cap 216 closes the opening 2151 and is the first wall 211.

[0434] It should be noted that the structure of the battery cell 20 can be varied. In some embodiments, the outer casing 21 may include a housing 215 and two end caps 216. The housing 215 has an internal cavity for accommodating the electrode assembly 22. The housing 215 has openings 2151 at both ends in the thickness direction of the first wall 211, and both openings 2151 communicate with the cavity. The two end caps 216 respectively close the two openings 2151, and one of the end caps 216 is the first wall 211.

[0435] The housing 215 of the outer casing 21 has openings 2151 at both ends of the first wall 211 in the thickness direction, and two end caps 216 respectively close the two openings 2151. The first wall 211 is one of the two end caps 216. The battery cell 20 with this structure is easy to assemble from both ends of the housing 215, which helps to reduce the manufacturing and assembly difficulty of the battery cell 20.

[0436] When the end cap 216 is the first wall 211, the pressure relief component 214 is disposed on the end cap 216, which is simple and convenient to manufacture. When the housing 215 includes the first wall 211, the pressure relief component 214 is disposed on one 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, which helps to reduce the risk of short circuit of the battery cell 20.

[0437] This application embodiment also provides a battery 100, which includes the battery cell 20 described above.

[0438] This application embodiment also provides an electrical device, which includes the aforementioned battery cell 20.

[0439] According to some embodiments of this application, please refer to Figures 3-7 .

[0440] This application provides a battery cell 20, which includes 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 weak portion 2144, which defines a predetermined pressure relief area 21431. The pressure relief component 214 is configured 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 also includes a second weak 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 has the first weak portion 2144 and the second weak portion 2145. When the battery cell 20 is depressurized, the first weak portion 2144 splits to allow the fluid medium inside the battery cell 20 to flow out and relieve pressure. By setting a second weak part 2145, the strength of the pressure relief component 214 at the second weak part 2145 position 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, achieving rapid pressure relief, reducing the risk of battery cell 20 explosion and fire, and helping to improve the reliability of battery cell 20.

[0441] 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 part 2144 and the first outer surface 2121 is L1, and the minimum distance between the first weak part 2144 and the second outer surface 2131 is L2, satisfying: 0≤|L1-L2| / L≤0.1. When 0≤|L1-L2| / L≤0.1, the position of the first weak part 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 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 the first weak part 2144 cracking before the second weak part 2145, so that the predetermined depressurization area 21431 can be flipped open under the guidance of the second weak part 2145, which is beneficial to improving the reliability of the battery cell 20.

[0442] 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, the cross-sectional area of ​​the weak segment perpendicular to its extension direction is S1, and 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. At this point, the second weak portion 2145 is close to the first outer surface 2121. The stiffness of the first wall 211 at the position of the second weak portion 2145 differs significantly from the stiffness at the position of the first weak portion 2144. Stiffness has a significant impact on the cracking of the first and second weak portions 2144 and 2145. If the influence of stiffness on the first and second weak portions 2144 and 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 segment perpendicular to its extension direction, i.e., 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 plays a guiding role in the predetermined pressure relief zone 21431. However, considering that stiffness has a significant impact on the cracking of the first weak part 2144 and the second weak part 2145 (under the same cross-sectional area, the second weak part 2145 is more difficult to crack than the first weak part 2144, therefore, the cross-sectional area of ​​the second weak part 2145 can be set to be smaller), when 0.7 < S2 / S1 ≤ 1, the first weak part 2144 can open and relieve pressure before the second weak part 2145, and the second weak part 2145 plays a guiding role for the predetermined pressure relief area 21431. Similarly, since stiffness has a significant impact on the cracking of the first weak part 2144 and the second weak part 2145, when S2 / S1 ≤ 1.5, the strength of the pressure relief component 214 at the position of the second weak part 2145 is smaller, and the resistance to the opening of the predetermined pressure relief area 21431 is smaller, making it easier for the predetermined pressure relief area 21431 to open under the action of the fluid medium.

[0443] 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, the cross-sectional area of ​​the weak segment perpendicular to its extension direction is S1, and 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 distance between the second weak portion 2145 and the center position of the first wall 211 along the first direction is small. At this time, the second weak portion 2145 is also relatively close to the center position of the first wall 211 along the first direction. The stiffness of the first wall 211 at the position of the second weak portion 2145 is similar to that at the position of the first weak portion 2144. Therefore, the stiffness has little impact on the cracking of the first weak portion 2144 and the second weak portion 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 plays a guiding role in the predetermined pressure relief zone 21431, reducing the risk that the second weak portion 2145 will crack before the first weak portion 2144. When S2 / S1≤5, the strength of the pressure relief component 214 at the second weak part 2145 is relatively small, which reduces 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 action of the fluid medium.

[0444] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, include: The outer shell has a first wall; A pressure relief component is disposed on the first wall. The pressure relief component includes a first weak portion that defines a predetermined pressure relief area. The pressure relief component is configured to split along at least a portion of the first weak portion when the battery cell is depressurized. The pressure relief component further includes a second weak portion, which is configured to guide at least a portion of the predetermined pressure relief zone to flip over, thereby opening at least a portion of the predetermined pressure relief zone; The first wall has a third outer surface facing away from the interior of the housing, and the projection of the first weak portion covers the center of the third outer surface along the thickness direction of the first wall; the housing includes a second wall and a third wall disposed opposite to each other along a first direction, the first wall connecting 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 housing, and the third wall has a second outer surface facing away from the interior of the housing; Along the first direction, a second weak portion is provided between the first weak portion and the first outer surface and / or between the first weak portion and the second outer surface.

2. The battery cell according to claim 1, characterized in that, The pressure relief component is provided with a first groove and a second groove. The pressure relief component forms a first weak portion in the area where the first groove is provided, and forms a second weak portion in the area where the second groove is provided. The first groove includes at least one groove segment. 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 extension direction is a first cross-sectional area. The minimum width of the bottom surface of the groove segment is a first width. 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 portion perpendicular to its extension direction is a second cross-sectional area. The minimum width of the bottom surface of the second groove is a second width. The minimum thickness of the second weak portion is a second thickness. The second cross-sectional area is equal to the product of the second width and the second thickness.

3. The battery cell according to claim 2, characterized in that, The first width is a1, satisfying: 0.01mm ≤ a1 ≤ 0.8mm; and / or The first thickness is h1, satisfying: 0.02mm ≤ h1 ≤ 1mm; and / or The second width is a2, satisfying: 0.01mm ≤ a2 ≤ 0.5mm; and / or The second thickness is h2, which satisfies: 0.1mm≤h2≤2mm.

4. The battery cell according to claim 3, characterized in that, 0.05mm≤a1≤0.5mm.

5. The battery cell according to claim 4, characterized in that, 0.1mm≤a1≤0.3mm.

6. The battery cell according to claim 3, characterized in that, 0.04mm≤h1≤0.6mm.

7. The battery cell according to claim 6, characterized in that, 0.08mm≤h1≤0.4mm.

8. The battery cell according to claim 3, characterized in that, 0.04mm≤a2≤0.3mm.

9. The battery cell according to claim 8, characterized in that, 0.06mm≤a2≤0.15mm.

10. The battery cell according to claim 3, characterized in that, 0.2mm≤h2≤1.5mm.

11. The battery cell according to claim 10, characterized in that, 0.5mm≤h2≤1mm.

12. The battery cell according to claim 1, characterized in that, Along the first direction, the distance between the first outer surface and the second outer surface is the first distance, the minimum distance between the first weak part and the first outer surface is the second distance, the minimum distance between the first weak part and the second outer surface is the 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.

13. The battery cell according to claim 2, characterized in that, 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 part and the first outer surface is a fourth distance, and 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 of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area, and the cross-sectional area of ​​the second weak part 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.

14. The battery cell according to claim 12, characterized in that, The third outer surface is rectangular, and the first direction is parallel to the width direction of the rectangle.

15. The battery cell according to claim 13, characterized in that, 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.

16. The battery cell according to claim 2, characterized in that, 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 part and the first outer surface is a fourth distance, and 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 of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area, and the cross-sectional area of ​​the second weak part 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.

17. The battery cell according to claim 16, characterized in that, The third outer surface is rectangular, and the first direction is parallel to the length direction of the rectangle.

18. The battery cell according to claim 16, characterized in that, 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.

19. The battery cell according to claim 16, characterized in that, 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.

20. The battery cell according to claim 13, characterized in that, The first cross-sectional area is S1, which satisfies: 0.0002 mm. 2 ≤S1≤0.8mm.

21. The battery cell according to claim 20, characterized in that, 0.002mm 2 ≤S1≤0.3mm 2 。 22. The battery cell according to claim 21, characterized in that, 0.008mm 2 ≤S1≤0.12mm 2 。 23. The battery cell according to claim 13, characterized in that, The second cross-sectional area is S2, which satisfies: 0.001mm. 2 ≤S2≤1mm 2 .

24. The battery cell according to claim 23, characterized in that, 0.008mm 2 ≤S2≤0.45mm 2 。 25. The battery cell according to claim 24, characterized in that, 0.03mm 2 ≤S2≤0.15mm 2 。 26. The battery cell according to any one of claims 1-25, characterized in that, The pressure relief component is provided with a second groove, and the pressure relief component forms a second weak part in the area where the second groove is provided. The second groove is provided on the surface of the pressure relief component facing the inside of the housing.

27. The battery cell according to any one of claims 1-25, characterized in that, The pressure relief component has a first surface and a second surface disposed 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 a first weak part in the area where the first groove is provided. The second surface is provided with a second groove, and the pressure relief component forms a second weak part in the area where the second groove is provided.

28. The battery cell according to claim 27, characterized in that, The first surface is the surface of the pressure relief component that faces away from the inside of the housing, and the second surface is the surface of the pressure relief component that faces the inside of the housing.

29. The battery cell according to any one of claims 1-25, characterized in that, The pressure relief component is provided with a first groove, and the pressure relief component forms a first weak part in the area where the first groove is provided. The first groove includes a first groove segment and a second groove segment, and the first groove segment and the second groove segment are connected. The pressure relief component forms a weak segment in the areas where the first groove segment and the second groove segment are provided, and the two weak segments together define the predetermined pressure relief area.

30. The battery cell according to any one of claims 1-25, characterized in that, The pressure relief component is provided with a first groove, and the pressure relief component forms a first weak part in the area where the first groove is provided. The first groove includes a first groove segment, a second groove segment, and a third groove segment. The first groove segment and the third groove segment are arranged opposite to each other. The second groove segment connects the first groove segment and the third groove segment. The pressure relief component forms a weak segment in the area where the first groove segment, the second groove segment, and the third groove segment are provided. The three weak segments together define the predetermined pressure relief area.

31. The battery cell according to claim 30, characterized in that, The first weak section defines two predetermined pressure relief zones, which are located on both sides of the second groove segment, and each predetermined pressure relief zone is provided with at least one second weak section.

32. The battery cell according to claim 31, characterized in that, Each of the predetermined pressure relief zones is provided with a second weak point, the pressure relief component is provided with a second groove, the pressure relief component forms the second weak point in the area where the second groove is provided, and the first groove is located between the two second grooves.

33. The battery cell according to claim 30, characterized in that, The second groove segment is located at a position where it connects to the first groove segment, which is offset from both ends of the first groove segment. The second groove segment is located at a position where it connects to the third groove segment, which is offset from both ends of the third groove segment.

34. The battery cell according to claim 30, characterized in that, The pressure relief component is provided with a second groove, and the pressure relief component forms a second weak part in the area where the second groove is provided. The first groove segment, the second groove segment and the third groove segment are all spaced apart from the second groove.

35. The battery cell according to claim 34, characterized in that, The second groove segment and the second recess are arranged opposite each other along the first direction. Along the first direction, the first groove segment and the third groove segment are both spaced apart from the second recess.

36. The battery cell according to claim 35, characterized in that, The third outer surface is rectangular, and the first direction is parallel to the length or width direction of the rectangle.

37. The battery cell according to any one of claims 1-25, characterized in that, The pressure relief component has a first surface and a second surface that are disposed opposite to each other in the thickness direction of the first wall. The pressure relief component is provided with a first groove. The first groove includes multiple levels of grooves arranged sequentially along the direction from the first surface to the second surface. In two adjacent levels of grooves, the first level groove that is away from the first surface is disposed on the bottom surface of the first level groove that is close to the first surface. The bottom wall of the first-level groove, which is furthest from the first surface among the multi-level grooves, is the first weak part.

38. The battery cell according to any one of claims 1-25, characterized in that, The pressure relief component is integrally formed with the first wall.

39. The battery cell according to any one of claims 1-25, characterized in that, The pressure relief component is separately disposed 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.

40. The battery cell according to any one of claims 1-25, characterized in that, The battery cell includes an electrode assembly, which is housed within the housing, and the first wall supports the electrode assembly along the direction of gravity.

41. The battery cell according to any one of claims 1-25, characterized in that, The battery cell includes electrode terminals, which are disposed on the other walls of the housing other than the first wall.

42. The battery cell according to claim 41, characterized in that, The electrode terminals are disposed on the wall of the housing opposite to the first wall.

43. The battery cell according to any one of claims 1-25, characterized in that, The outer casing includes: The shell has an opening; End cap, connected to the housing and closing the opening; Wherein, the end cap is the first wall, or the housing includes the first wall.

44. The battery cell according to any one of claims 1-25, characterized in that, The material of the first wall may be steel or aluminum alloy.

45. A battery, characterized in that, Includes the battery cell according to any one of claims 1-44.

46. ​​An electrical appliance, characterized in that, Includes the battery cell according to any one of claims 1-44.

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