Battery monomer, battery and electric equipment

Abstract

The utility model provides a battery monomer, a battery and electric equipment, and relates to the field of batteries. The battery cell includes a housing having a first wall and a pressure relief member. The pressure relief component is arranged on the first wall, the pressure relief component comprises a first weak part, the first weak part defines a preset pressure relief area, and the pressure relief component is configured to be capable of cracking along at least one part of the first weak part when the battery monomer is subjected to pressure relief. The pressure relief component further comprises a second weak part, and the second weak part is configured to guide at least one part of the preset pressure relief area to turn over so as to open at least one part of the preset pressure relief area. Each battery monomer is provided with a first weak part and a second weak part, and when the pressure of the battery monomer is released, the first weak part is cracked, so that a fluid medium in the battery monomer flows out to release the pressure. By arranging the second weak part, the predetermined pressure relief area can be turned over and opened under the guidance of the second weak part, so that the opening speed of the predetermined pressure relief area is favorably improved, quick pressure relief is realized, and the reliability of the single battery is favorably improved.

Description

Technical Field

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

[0002] Batteries are widely used in the field of new energy, such as electric vehicles and new energy vehicles. New energy vehicles and electric vehicles have become a new trend in the development of the automotive industry. The development of battery technology must consider many design factors at the same time, such as battery life, energy density, discharge capacity, charge and discharge rate and other performance parameters. In addition, the reliability of the battery must also be considered. However, the reliability of current batteries is poor. Utility Model Content

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

[0004] In a first aspect, an embodiment of the present application provides a battery cell, comprising an outer shell and a pressure relief component, wherein the outer shell has a first wall; the pressure relief component is arranged on the first wall, the pressure relief component comprises a first weak portion, the first weak portion defines a predetermined pressure relief area, and the pressure relief component is configured to be able to split along at least a portion of the first weak portion when the battery cell is pressure-released; wherein the pressure relief component also comprises a second weak portion, and the second weak portion is configured to guide at least a portion of the predetermined pressure relief area to flip so as 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 portion and a second weak portion. When the battery cell is depressurized, the first weak portion is split to allow the fluid medium in the battery cell to flow out and release pressure. By providing the second weak portion, the strength of the pressure relief component at the second weak portion is weakened, making it easier for the predetermined pressure relief area to flip open under the action of the fluid medium, which can not only increase the probability of the predetermined pressure relief area opening, but also increase the opening speed of the predetermined pressure relief area, achieve rapid pressure relief, reduce the risk of battery cell explosion and fire, and help improve the reliability of the battery cell.

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

[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, and the rigidity of the position of the first weak portion is less than the rigidity of the position of the second weak portion. When the battery cell is depressurized, the deformation of the pressure relief component at the position of the first weak portion is greater than the deformation of the pressure relief component at the position of the second weak portion, which is conducive to the first weak portion being cracked before the second weak portion, so that the predetermined pressure relief area can be flipped open under the guidance of the second weak portion. Similarly, when a second weak portion is provided between the first weak portion and the second outer surface, the second weak portion is closer to the second outer surface than the first weak portion, and the rigidity of the position of the first weak portion is less than the rigidity of the position of the second weak portion. When the battery cell is depressurized, the deformation of the pressure relief component at the position of the first weak portion is greater than the deformation of the pressure relief component at the position of the second weak portion, which is conducive to the first weak portion being cracked before the second weak portion, so that the predetermined pressure relief area can be flipped open under the guidance of the second weak portion.

[0008] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a first groove and a second groove, the pressure relief component forms the first weak portion in the area where the first groove is provided, and the pressure relief component forms the second weak portion in the area where the second groove is provided, the first groove includes at least one groove segment, 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 groove 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 perpendicular to its extension direction is a second cross-sectional area, the minimum width of the groove bottom surface of the second groove is the second width, the minimum thickness of the second weak portion is a second thickness, and 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 weak portion and the second weak portion are formed by providing the first groove and the second groove on the pressure relief component, which is simple, convenient and low in 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 section perpendicular to its extension direction is rectangular. When measuring the first cross-sectional area, the first width and the first thickness can be obtained by measuring, thereby calculating the first cross-sectional area. The second cross-sectional area is equal to the product of the second width and the second thickness, that is, the cross section of the second weak portion perpendicular to its extension direction is rectangular. When measuring the second cross-sectional area, the second width and the second thickness can be obtained by measuring, thereby calculating the second cross-sectional area.

[0010] As an optional technical solution of an embodiment of the present application, the first width is a1, satisfying: 0.01mm≤a1≤0.8mm, optionally, 0.05mm≤a1≤0.5mm, optionally, 0.1mm≤a1≤0.3mm; and / or the first thickness is h1, satisfying: 0.02mm≤h1≤1mm, optionally, 0.04mm≤h1≤0.6mm, optionally, 0.08mm≤h1≤0.4mm; and / or the second width is a2, satisfying: 0.01mm≤a2≤0.5mm, optionally, 0.04mm≤a2≤0.3mm, optionally, 0.06mm≤a2≤0.15mm; and / or the second thickness is h2, satisfying: 0.1mm≤h2≤2mm, optionally, 0.2mm≤h2≤1.5mm, optionally, 0.5mm≤h2≤1mm.

[0011] In the above technical solution, when a1≥0.01mm, the first width is relatively large, which can reduce the risk of the weak section cracking due to changes in the air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When a1≤0.8mm, the first width is not too large, which is beneficial to make the weak section crack in time when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell. Therefore, when 0.01mm≤a1≤0.8mm, the first width is moderate, the weak section is not easy to crack due to changes in the air pressure inside the battery cell, and can be cracked in time when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell.

[0012] When a1≥0.05mm, the first width is larger, which can further reduce the risk of the weak section cracking due to the change in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When a1≤0.5mm, it is beneficial to make the weak section crack more timely when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure release of the battery cell. Therefore, when 0.05mm≤a1≤0.5mm, the reliability and timeliness of the pressure release of the battery cell are better taken into account.

[0013] When a1≥0.1mm, the first width is larger, which can further reduce the risk of the weak section cracking due to the change in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When a1≤0.3mm, it is beneficial to make the weak section crack more timely when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure release of the battery cell. Therefore, when 0.1mm≤a1≤0.3mm, the reliability and timeliness of the pressure release of the battery cell are better taken into account.

[0014] When h1≥0.02mm, the first thickness is relatively large, which can reduce the risk of the weak section cracking due to changes in the air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When h1≤1mm, the first thickness is not too large, which is beneficial to the weak section to crack in time when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell. Therefore, when 0.02mm≤h1≤1mm, the first thickness is moderate, the weak section is not easy to crack due to changes in the air pressure inside the battery cell, and can be cracked in time when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell.

[0015] When h1≥0.04mm, the first thickness is larger, which can further reduce the risk of the weak section cracking due to the change in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When h1≤0.6mm, it is beneficial to make the weak section crack more timely when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure release of the battery cell. Therefore, when 0.04mm≤h1≤0.6mm, the reliability and timeliness of the pressure release of the battery cell are better taken into account.

[0016] When h1≥0.08mm, the first thickness is larger, which can further reduce the risk of the weak section cracking due to the change in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When h1≤0.4mm, it is beneficial to make the weak section crack more timely when the battery cell is depressurized, which is beneficial to improving the timeliness of the pressure release of the battery cell. Therefore, when 0.08mm≤h1≤0.4mm, the reliability and timeliness of the pressure release of the battery cell are better taken into account.

[0017] When a2≥0.01mm, the second width is relatively large, which can reduce the risk of the second weak part cracking due to changes in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When a2≤0.5mm, the second width is not too large, which is beneficial to reducing the resistance to the flipping of the predetermined pressure relief area, facilitating the rapid flipping and opening of the predetermined pressure relief area, and is beneficial to improving the timeliness of the pressure relief of the battery cell. Therefore, when 0.01mm≤a2≤0.5mm, the second width is moderate in size, and the second weak part is not easy to crack due to changes in air pressure inside the battery cell, and is convenient for the rapid flipping and opening of the predetermined pressure relief area, which is beneficial to improving the timeliness of the pressure relief of the battery cell.

[0018] When a2≥0.04mm, the second width is larger, which can further reduce the risk of the second weak part cracking due to the change in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When a2≤0.3mm, the resistance to the flipping of the predetermined pressure relief area is smaller, which facilitates the rapid flipping and opening of the predetermined pressure relief area, which is beneficial to improving the timeliness of the pressure relief of the battery cell. Therefore, when 0.04mm≤a2≤0.3mm, the reliability and timeliness of the pressure relief of the battery cell are better taken into account.

[0019] When a2≥0.06mm, the second width is larger, which can further reduce the risk of the second weak part cracking due to the change in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When a2≤0.15mm, the resistance to the flipping of the predetermined pressure relief area is smaller, which facilitates the rapid flipping and opening of the predetermined pressure relief area, which is beneficial to improving the timeliness of the pressure relief of the battery cell. Therefore, when 0.06mm≤a2≤0.15mm, the reliability and timeliness of the pressure relief of the battery cell are better taken into account.

[0020] When h2≥0.1mm, the second thickness is relatively large, which can reduce the risk of the second weak part cracking due to changes in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When h2≤2mm, the second thickness is not too large, which is beneficial to reducing the resistance to the flipping of the predetermined pressure relief area, facilitating the rapid flipping and opening of the predetermined pressure relief area, and is beneficial to improving the timeliness of the pressure relief of the battery cell. Therefore, when 0.1mm≤h2≤2mm, the second thickness is moderate, the second weak part is not easy to crack due to changes in air pressure inside the battery cell, and is convenient for the rapid flipping and opening of the predetermined pressure relief area, which is beneficial to improving the timeliness of the pressure relief of the battery cell.

[0021] When h2≥0.2mm, the second thickness is larger, which can further reduce the risk of the second weak part cracking due to the change in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When h2≤1.5mm, the resistance to the flipping of the predetermined pressure relief area is smaller, which facilitates the rapid flipping and opening of the predetermined pressure relief area, which is beneficial to improving the timeliness of pressure relief of the battery cell. Therefore, when 0.2mm≤h2≤1.5mm, the reliability and timeliness of pressure relief of the battery cell are better taken into account.

[0022] When h2≥0.5mm, the second thickness is larger, which can further reduce the risk of the second weak part cracking due to the change in air pressure inside the battery cell, which is beneficial to improving the reliability of the battery cell. When h2≤1mm, the resistance to the flipping of the predetermined pressure relief area is smaller, which facilitates the rapid flipping and opening of the predetermined pressure relief area, which is beneficial to improving the timeliness of pressure relief of the battery cell. Therefore, when 0.5mm≤h2≤1mm, the reliability and timeliness of pressure relief of the battery cell are better taken into account.

[0023] As an optional technical solution of an embodiment of the present application, along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the first weak portion and the first outer surface is a second distance, the minimum distance between the first weak portion and the second outer surface is a third distance, and the ratio of the difference between the second distance and the third distance to the first distance is greater than or equal to 0 and less than or equal to 0.1.

[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 portion is close to the middle position of the first wall along the first direction, and the stiffness of the middle position of the first wall along the first direction is relatively small. When the battery cell is depressurized, the middle position of the first wall along the first direction will undergo a large deformation, which is conducive to the first weak portion cracking before the second weak portion, so that the predetermined pressure relief area can be flipped open under the guidance of the second weak portion, which is conducive to improving the reliability of the battery cell.

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

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

[0027] As an optional technical solution of an embodiment of the present application, along the first direction, the second weak portion is arranged between the first weak portion and the first outer surface; along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the second weak portion and the first outer surface is a fourth distance, and the minimum distance between the second weak portion and the second outer surface is a fifth distance, the first weak portion includes at least one weak segment, 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, and 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 distance that the second weak portion deviates from the middle position of the first wall along the first direction is large. At this time, the second weak portion is close to the first outer surface, and the stiffness of the first wall at the position of the second weak portion is greatly different from the stiffness of the first wall at the position of the first weak portion, and the stiffness has a greater impact on the cracking of the first weak portion and the second weak portion. If the impact of the stiffness on the first weak portion and the second weak portion is not considered, the cross-sectional area of ​​the second weak portion perpendicular to its extension direction only needs to be greater than the cross-sectional area of ​​the weak section perpendicular to its extension direction, that is, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1, so that the first weak portion opens to release pressure before the second weak portion, and the second weak portion plays a guiding role in the predetermined pressure relief area. However, considering that the rigidity has a greater impact on the cleavage of the first weak part and the second weak part (under the same cross-sectional area, the second weak part is more difficult to cleave than the first weak part, so the cross-sectional area of ​​the second weak part can be set to be smaller), when the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1, the first weak part can also be opened to release pressure before the second weak part, and the second weak part plays a guiding role in the predetermined pressure relief area. Similarly, since the rigidity has a greater impact on the cleavage of the first weak part and the second weak part, when the ratio of the second cross-sectional area to the first cross-sectional area is less than or equal to 1.5, the strength of the pressure relief component at the second weak part is smaller, and the obstacle to the flipping and opening of the predetermined pressure relief area is smaller, making it easier for the predetermined pressure relief area to flip open under the action of the fluid medium.

[0029] As an optional technical solution of an embodiment of the present application, the first wall has a third outer surface facing away from the interior of the shell, the third outer surface is a rectangle, and the first direction is parallel to the width direction of the rectangle.

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

[0031] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a first groove and a second groove, the pressure relief component forms the first weak portion in the area where the first groove is provided, and the pressure relief component forms the second weak portion in the area where the second groove is provided, the first groove includes at least one groove section, the pressure relief component forms a weak section in the area where the groove section is provided, the cross-sectional area of ​​the weak section perpendicular to its extension direction is a first cross-sectional area, the minimum width of the groove bottom surface of the groove section is a first width, the minimum thickness of the weak section 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 perpendicular to its extension direction is a second cross-sectional area, the minimum width of the groove bottom surface of the second groove is the second width, the minimum thickness of the second weak portion is a second thickness, and the second cross-sectional area is equal to the product of the second width and the second thickness; the second thickness is greater than or equal to the first thickness, and the second width is less than or equal to the first width.

[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 portion better guide the opening of the predetermined pressure relief area, but also the second width can be made as small as possible under the condition that when the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1.5, thereby reducing the area occupied by the second groove on the third outer surface of the pressure relief component.

[0033] As an optional technical solution of an embodiment of the present application, along the first direction, the second weak portion is arranged between the first weak portion and the first outer surface; along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the second weak portion and the first outer surface is a fourth distance, and the minimum distance between the second weak portion and the second outer surface is a fifth distance, the first weak portion includes at least one weak segment, 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, and 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 that the second weak portion deviates from the middle position of the first wall along the first direction is small. At this time, the second weak portion is also relatively close to the middle position of the first wall along the first direction. The stiffness of the first wall at the position of the second weak portion is slightly different from the stiffness of the first wall at the position of the first weak portion, and the stiffness has little effect on the cracking of the first weak portion and the second weak portion. When the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1.5, the first weak portion can be opened and depressurized before the second weak portion, and the second weak portion plays a guiding role in the predetermined pressure relief area, reducing the risk of the second weak portion cracking before the first weak portion. When the ratio of the second cross-sectional area to the first cross-sectional area is less than or equal to 5, the strength of the pressure relief component at the position of the second weak portion is small, and the obstacle to the flipping and opening of the predetermined pressure relief area is small, making it easier for the predetermined pressure relief area to flip and open under the action of the fluid medium.

[0035] As an optional technical solution of an embodiment of the present application, the first wall has a third outer surface facing away from the interior of the shell, the third outer surface is a rectangle, and the first direction is parallel to the length direction of the rectangle.

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

[0037] As an optional technical solution of an embodiment of the present application, the ratio of the second cross-sectional area to the first cross-sectional area is greater than or equal to 2.13 and less than or equal to 4.67.

[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 portion can be opened and pressure-released before the second weak portion, and the second weak portion plays a guiding role in the predetermined pressure-release area, further reducing the risk of the second weak portion cracking before the first weak portion. When the ratio of the second cross-sectional area to the first cross-sectional area is less than or equal to 4.67, the strength of the pressure-release component at the second weak portion is smaller, and the obstacle to the predetermined pressure-release area flipping open is smaller, making it easier for the predetermined pressure-release area to flip open under the action of the fluid medium.

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

[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 in different areas of the first wall on the cracking of the weak section and the second weak portion can be further reduced, so that the weak section cracks when the battery cell is depressurized, and the second weak portion guides the flipping of the predetermined pressure relief area.

[0041] As an optional technical solution of the embodiment of the present application, the first cross-sectional area is S1, which satisfies: 0.0002mm 2 ≤S1≤0.8mm 2 , optionally, 0.002mm 2 ≤S1≤0.3mm 2 , optionally, 0.008mm 2 ≤S1≤0.12mm 2 .

[0042] In the above technical solution, when S1≥0.0002mm 2 When S1≤0.8mm, the cross-sectional area of ​​the first weak section perpendicular to its extension direction is larger, and it is not easy to crack when subjected to external impact, which is beneficial to improving the reliability of the battery cell. 2 When the cross-sectional area of ​​the first weak section perpendicular to its extension direction is not too large, when the internal pressure of the battery cell reaches the detonation pressure, the first weak section is easy to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.8mm 2 It can take into account both resistance to external impact and easy opening of pressure relief when the internal pressure of the battery cell reaches the detonation pressure.

[0043] When S1≥0.002mm2 When S1≤0.3mm, the risk of the first weak section cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell. 2 When the internal pressure of the battery cell reaches the detonation pressure, the first weak section is more likely to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.3mm 2 It can better resist external impact and is easy to open and release pressure when the internal pressure of the battery cell reaches the detonation pressure.

[0044] When S1≥0.008mm 2 When S1≤0.12mm, the risk of the first weak section cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell. 2 When the internal pressure of the battery cell reaches the detonation pressure, the first weak section is more likely to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.12mm 2 It can better resist external impact and is easy to open and release pressure when the internal pressure of the battery cell reaches the detonation pressure.

[0045] As an optional technical solution of the embodiment of the present application, the second cross-sectional area is S2, which satisfies: 0.001mm 2 ≤S2≤1mm 2 , optionally, 0.008mm 2 ≤S2≤0.45mm 2 ; Optionally, 0.03mm 2 ≤S2≤0.15mm 2 .

[0046] In the above technical solution, when S2≥0.001mm 2 When S2≤1mm, the cross-sectional area of ​​the second weak part perpendicular to its extension direction is larger, and it is not easy to crack when subjected to external impact, which is beneficial to improving the reliability of the battery cell. 2 When the cross-sectional area of ​​the second weak portion perpendicular to its extension direction is not too large, it is beneficial to reduce the resistance of the predetermined pressure relief area to turn over, and facilitate the predetermined pressure relief area to turn over and open quickly. 2 ≤S2≤1mm 2 , which can both resist external impact and facilitate rapid flipping and opening of the predetermined pressure relief area.

[0047] When S2≥0.008mm 2 When S2≤0.45mm, the risk of the second weak part cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell.2 , the resistance to the predetermined pressure relief area turning over is smaller, which facilitates the predetermined pressure relief area to turn over and open quickly. 2 ≤S2≤0.45mm 2 When opening, it can better resist external impact and facilitate quick flipping and opening of the predetermined pressure relief area.

[0048] When S2≥0.03mm 2 When S2≤0.15mm, the risk of the second weak part cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell. 2 , the resistance to the predetermined pressure relief area turning over is smaller, which facilitates the predetermined pressure relief area to turn over and open quickly. 2 ≤S2≤0.15mm 2 When opening, it can better resist external impact and facilitate quick flipping and opening of the predetermined pressure relief area.

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

[0050] In the above technical solution, the second weak portion is formed by opening the second groove on the pressure relief component, which is simple, convenient and low in cost. In addition, the second groove is arranged on the surface of the pressure relief component facing the inside of the shell, and the tension that the predetermined pressure relief area needs to overcome when flipping is small, so that the predetermined pressure relief area is easy to flip open quickly, which is conducive to improving the reliability of the battery cell.

[0051] As an optional technical solution of an embodiment of the present application, the pressure relief component has a first surface and a second surface that are relatively arranged in the thickness direction of the first wall, the first surface is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, and the second surface is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided.

[0052] In the above technical solution, the first weak portion and the second weak portion are formed by providing the first groove and the second groove on the pressure relief component, which is simple, convenient and low in cost. The first groove and the second groove are respectively provided on the first surface and the second surface of the pressure relief component, so that the first groove and the second groove are respectively located on both sides of the pressure relief component, thereby facilitating the processing of the first groove and the second groove on both sides of the pressure relief component, and facilitating the mutual influence of the first groove and the second groove during the processing.

[0053] As an optional technical solution of an embodiment of the present application, the first surface is a surface of the pressure relief component facing away from the interior of the shell, and the second surface is a surface of the pressure relief component facing the interior of the shell.

[0054] In the above technical solution, by arranging the first groove on the surface of the pressure relief component facing away from the inside of the shell, the tension that the first weak part needs to overcome when cracking is small, and it is easy to crack. By arranging the second groove on the surface of the pressure relief component facing the inside of the shell, the tension that the predetermined pressure relief area needs to overcome when flipping is small, so that the predetermined pressure relief area is easy to flip and open quickly, which is beneficial to improving the reliability of the battery cell.

[0055] As an optional technical solution of an embodiment of the present application, the pressure relief component is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, the first groove includes a first groove section and a second groove section, the first groove section and the second groove section are connected, and the pressure relief component forms a weak section in the area where the first groove section and the second groove section are provided, respectively, and the two weak sections jointly define the predetermined pressure relief area.

[0056] In the above technical solution, the first groove section and the second groove section are interconnected structures, so that the first groove section and the second groove section jointly define a predetermined pressure relief area. On the one hand, the pressure relief area of ​​the battery cell can be increased to increase the pressure relief rate of the battery cell. On the other hand, the position where the first groove section and the second groove section are interconnected is weaker, which is 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 of an embodiment of the present application, the pressure relief component is provided with a first groove, and the pressure relief component forms the first weak portion in the area where the first groove is provided, the first groove includes a first groove section, a second groove section and a third groove section, the first groove section and the third groove section are arranged opposite to each other, the second groove section connects the first groove section and the third groove section, and the pressure relief component forms a weak section in the area where the first groove section, the second groove section and the third groove section are provided, respectively, and the three weak sections jointly define the predetermined pressure relief area.

[0058] In the above technical solution, the first groove includes a first groove section, a second groove section and a third groove section, and the second groove section connects the first groove section and the third groove section, so that the pressure relief component can split along the first groove section, the second groove section and the third groove section when the battery cell is relieved of pressure, so as to open the predetermined pressure relief area to release the internal pressure of the battery cell. The first groove with such a structure makes the connection position between the first groove section and the second groove section and the connection position between the first groove section and the third groove section weaker, and is easier to split and open the predetermined pressure relief area for pressure relief, and can further improve the pressure relief area and pressure relief rate of the battery cell.

[0059] As an optional technical solution of an embodiment of the present application, the first weak portion defines two predetermined pressure relief areas, the two predetermined pressure relief areas are respectively located on both sides of the second groove section, and at least one second weak portion is correspondingly arranged in each predetermined pressure relief area.

[0060] In the above technical solution, the first weak portion defines two predetermined pressure relief areas, each of which is correspondingly provided with at least one second weak portion. When the battery cell is pressure-released, the two predetermined pressure relief areas are flipped open under the guidance of the corresponding second weak portions, so that the battery cell has a larger pressure relief area, which is beneficial to improving the pressure relief rate of the battery cell and improving the reliability of the battery cell.

[0061] As an optional technical solution of an embodiment of the present application, a second weak portion is correspondingly arranged in each predetermined pressure relief area, the pressure relief component is provided with a second groove, the pressure relief component forms the second weak portion in the area 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 to the second weak part one by one, which can reduce the number of second weak parts, reduce the number of times the pressure relief component is processed, and reduce the stress of the pressure relief component. The first groove is set between the two second grooves. When the battery cell is depressurized, the pressure relief component can be split along the first groove section, the second groove section and the third groove section, thereby opening the two predetermined pressure relief areas, so that the two predetermined pressure relief areas are flipped open under the guidance of the corresponding second weak parts, so that the battery cell has a larger pressure relief area, which is conducive to improving the pressure relief rate of the battery cell and improving the reliability of the battery cell.

[0063] As an optional technical solution of an embodiment of the present application, the position where the second slot segment is connected to the first slot segment deviates from the two ends of the first slot segment, and the position where the second slot segment is connected to the third slot segment deviates from the two ends of the third slot segment.

[0064] In the above technical solution, by setting the connection position between the second groove section and the first groove section to be located between the two ends of the second groove section, and setting the connection position between the second groove section and the third groove section to be located between the two ends of the third groove section, so that the first groove section, the second groove section and the third groove section form a structure similar to an "H" shape, both sides of the second groove section 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 for pressure relief 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 of an embodiment of the present application, the pressure relief component is provided with a second groove, and the pressure relief component forms the second weak portion in the area where the second groove is provided, and the first groove section, the second groove section and the third groove section are all spaced apart from the second groove.

[0066] In the above technical solution, by arranging the first groove section, the second groove section and the third groove section to be spaced apart from the second groove, on the one hand, the mutual influence between the first groove and the second groove during the processing can be reduced, and on the other hand, the phenomenon that the pressure relief component cracks along the second groove when the pressure relief component cracks along the first groove to relieve pressure can be reduced, and the stress influence between the area where the pressure relief component is set with the first groove and the area where the pressure relief component is set with the second groove can be reduced.

[0067] As an optional technical solution of an embodiment of the present application, the second slot segment and the second groove are arranged opposite to each other along a first direction, and along the first direction, the first slot segment and the third slot segment are both arranged at intervals from the second groove.

[0068] In the above technical solution, by making the second groove section and the second groove be arranged opposite to each other along the first direction, the first groove section and the third groove section are both arranged spaced apart from the second groove in the first direction, so that the predetermined pressure relief area defined by the first groove section, the second groove section and the third groove section can be flipped around the area where the second groove is provided in the pressure relief component when it is opened, and the flipping angle of the predetermined pressure relief area after being opened can be increased, so as to increase the pressure relief area of ​​the battery cell.

[0069] As an optional technical solution of an embodiment of the present application, the first wall has a third outer surface facing away from the interior of the shell, the third outer surface is a rectangle, 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 section and the second groove are arranged along the length direction or width direction of the third outer surface, and the first groove section and the third groove section are spaced from the second groove along the length direction or width direction of the third outer surface. The space in the length direction or width direction of the third outer surface is large, and it is easy to process the first groove and the second groove. In addition, during production, the detonation pressure of multiple processed battery cells is relatively consistent.

[0071] As an optional technical solution of an embodiment of the present application, the pressure relief component has a first surface and a second surface arranged opposite to each other in the thickness direction of the first wall, and the pressure relief component is provided with a first groove, and the first groove includes a plurality of grooves arranged in sequence from the first surface to the second surface, and in two adjacent levels of the grooves, a first-level groove away from the first surface is arranged on the groove bottom surface of the first-level groove close to the first surface; wherein the groove bottom wall of the first-level groove farthest from the first surface among the multi-level grooves is the first weak portion.

[0072] In the above technical solution, the multi-level grooves are sequentially arranged on the pressure relief component along the direction from the first surface to the second surface. During molding, the multi-level grooves can be molded step by step, thereby reducing the molding force on the pressure relief component and reducing the risk of cracks in the pressure relief component. The pressure relief component is not easy to fail due to cracks in the position where the grooves are set, thereby improving the reliability of the battery cell. When molding the multi-level grooves, stamping or cold heading can be used, so that the groove wall will undergo cold work hardening (the grain arrangement changes, resulting in lattice distortion, reducing the plasticity of the metal and increasing the hardness of the material), and its ability to resist external impact is enhanced, and it is not easily damaged by external impact. In this way, it is helpful to reduce the risk of leakage in the pressure relief component.

[0073] As an optional technical solution of the embodiment of the present application, 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, and no additional welding or bonding process is required, which is conducive to reducing the risk of leakage of the pressure relief component. In addition, during production, it is easy to make the detonation pressure of multiple processed battery cells more consistent.

[0075] As an optional technical solution of an embodiment of the present application, the pressure relief component is separately provided from the first wall, the first wall is provided with a pressure relief hole, and the pressure relief component is installed on the first wall and covers the pressure relief hole.

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

[0077] As an optional technical solution of the embodiment of the present application, the battery cell includes an electrode assembly, the electrode assembly is accommodated in the housing, and the first wall supports the electrode assembly along the direction of gravity.

[0078] In the above technical solution, the first wall supports the electrode assembly along the direction of gravity, and the pressure relief component is arranged on the first wall. In this way, when the battery cell is depressurized, the ejected fluid medium is not easy to act on other electrical connection components, thereby reducing the risk of short circuit when the battery cell is depressurized.

[0079] As an optional technical solution of the embodiment of the present application, the battery cell includes an electrode terminal, and the electrode terminal is arranged on other walls of the housing except the first wall.

[0080] In the above technical solution, the electrode terminals and the pressure relief component are respectively arranged on different walls of the shell. When the battery cell is depressurized, the ejected fluid medium is not easy to act on the electrode terminals and cause the electrode terminals to short-circuit, thereby reducing the risk of short circuit when the battery cell is depressurized.

[0081] As an optional technical solution of the embodiment of the present application, the electrode terminal is arranged on a wall of the housing opposite to the first wall.

[0082] In the above technical solution, the electrode terminal is arranged on the wall of the shell opposite to the first wall, and the electrode terminal is far away from the pressure relief component. When the battery cell is depressurized, the sprayed fluid medium is less likely to act on the electrode terminal and cause the electrode terminal to short-circuit, further reducing the risk of short circuit when the battery cell is depressurized.

[0083] As an optional technical solution of an embodiment of the present application, the outer shell includes a shell and an end cover, the shell has an opening; the end cover is connected to the shell and closes the opening; wherein the end cover is the first wall, or the shell includes the first wall.

[0084] In the above technical solution, when the end cover is the first wall, the pressure relief component is arranged on the end cover, which is simple and convenient to manufacture. When the shell includes the first wall, the pressure relief component is arranged on a wall of the shell, and the fluid medium sprayed by the pressure relief component is not easy to act on other electrical connection structures on the end cover, which is conducive to reducing the risk of short circuit of the battery cell.

[0085] In a second aspect, an embodiment of the present application further provides a battery, which includes the above-mentioned battery cell.

[0086] In a third aspect, an embodiment of the present application further provides an electrical device, wherein the electrical device comprises the above-mentioned battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0088] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0089] Figure 2 An exploded view of the structure of a battery provided in some embodiments of the present application;

[0090] Figure 3 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0091] Figure 4 An exploded view of the structure of a battery cell provided in some embodiments of the present application;

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

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

[0094] Figure 7 for Figure 6 A partial enlarged view of the housing at A shown;

[0095] Figure 8 A bottom view of a housing of a battery cell provided in some other embodiments of the present application;

[0096] Fig. 9 A bottom view of a housing of a battery cell provided in some further embodiments of the present application;

[0097] Fig.10 A bottom view of a housing of a battery cell provided in some other embodiments of the present application;

[0098] Fig.11 A bottom view of a housing of a battery cell provided in some embodiments of the present application.

[0099] Icon: 1000-vehicle; 100-battery; 10-box; 11-first box body; 12-second box body; 20-battery cell; 21-housing; 211-first wall; 2111-first surface; 2112-second surface; 2113-third outer surface; 212-second wall; 2121-first outer surface; 213-third wall; 2131-second outer surface; 214-pressure relief component; 2141-first level groove; 2142-second level groove; 2 143-third-stage groove; 21431-predetermined pressure relief area; 2143a-first groove section; 2143b-second groove section; 2143c-third groove section; 2144-first weak portion; 2145-second weak portion; 21451-second groove; 2146-first groove; 215-shell; 2151-opening; 216-end cover; 22-electrode assembly; 221-ear; 23-electrode terminal; 24-current collecting member; 200-controller; 300-motor. DETAILED DESCRIPTION

[0100] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0101] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

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

[0103] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0104] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

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

[0106] The term "plurality" used in the present application refers to two or more (including two).

[0107] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0108] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0109] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0110] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet 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 electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0112] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0113] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc.

[0114] In some embodiments, the positive electrode may be a foamed metal. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, etc. When the foamed metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foamed metal, but of course, the positive electrode active material may also be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled or / and deposited in the foamed metal, and 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 may be a metal foil, a foamed metal or a composite current collector. For example, as the metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, nickel or titanium, etc. may be used. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, etc. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[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 facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0119] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0120] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0121] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0122] In some embodiments, the separator is a separator membrane. There may be many types of separator membranes, and any known porous separator membrane with good chemical stability and mechanical stability may be selected.

[0123] As an example, the material of the separator may include at least one of glass fiber, non-woven 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 may be attached to the surface of the positive and negative electrodes.

[0124] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0125] In some embodiments, the battery cell further includes an electrolyte, which plays a role in conducting ions between the positive and negative electrodes. The electrolyte can be liquid, gel or solid. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[0126] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0127] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent may also be an ether solvent. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

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

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

[0130] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, and the like.

[0131] As an example, the inorganic solid electrolyte may include an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0132] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0133] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0134] In some embodiments, the electrode assembly is a laminate structure.

[0135] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets may be alternately stacked.

[0136] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0137] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded sections that are stacked.

[0138] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0139] As an example, the separator may be disposed continuously, and may be disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

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

[0141] In some embodiments, the electrode assembly is provided with tabs, which can lead current out of 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 the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0143] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes but is not limited to a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc.

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

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

[0146] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are accommodated in the case.

[0147] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0148] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0149] Batteries are widely used in the field of new energy, such as electric vehicles and new energy vehicles. New energy vehicles and electric vehicles have become a new trend in the development of the automotive industry. The development of battery technology must consider many design factors at the same time, such as battery life, energy density, discharge capacity, charge and discharge rate and other performance parameters. In addition, the reliability of the battery must also be considered. However, the reliability of current batteries is poor.

[0150] For battery cells, in order to improve the reliability of battery cells, the prior art is to weld a pressure relief mechanism on the battery cells, and a weak portion is provided on the pressure relief mechanism, which defines a pressure relief portion. When the internal pressure of the battery cell reaches the detonation pressure, the weak portion cracks and the pressure relief portion opens to release the pressure inside the battery cell, thereby reducing the risk of explosion or fire of the battery cell.

[0151] However, when the battery cell releases pressure, often only a part of the weak part cracks, so that the pressure relief part may not be able to open, or the pressure relief part can only open a smaller opening, or although the pressure relief part can be fully opened, the opening speed is slow, resulting in a slow pressure relief speed, and the pressure inside the battery cell cannot be quickly released, so that the battery cell still has a greater risk of explosion and fire, resulting in poor reliability of the battery cell.

[0152] In view of this, an embodiment of the present application provides a battery cell, the battery cell includes a housing and a pressure relief component, the housing has a first wall, and the pressure relief component is arranged on the first wall. The pressure relief component includes a first weak portion, the first weak portion defines a predetermined pressure relief area, and the pressure relief component is configured to be able to split along at least a portion of the first weak portion when the battery cell is depressurized. Among them, the pressure relief component also includes a second weak portion, and the second weak portion is configured to guide at least a portion of the predetermined pressure relief area to flip, so as to open at least a portion of the predetermined pressure relief area.

[0153] 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 is split to allow the fluid medium in 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 is weakened, making it easier for the predetermined pressure relief area to flip open under the action of the fluid medium, which can not only increase the probability of the predetermined pressure relief area opening, but also increase the opening speed of the predetermined pressure relief area, achieve rapid pressure relief, reduce the risk of battery cell explosion and fire, and help improve the reliability of the battery cell.

[0154] The battery cells disclosed in the embodiments of the present application can be used in, but not limited to, electrical devices such as vehicles, ships or aircraft. A power supply system comprising the battery cells and batteries disclosed in the present application can be used to form the electrical device, which is beneficial to improving the reliability of the battery cells.

[0155] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0156] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device in an embodiment of the present application.

[0157] Please refer to Figure 1 , Figure 1A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom of the vehicle 1000, or at the head of the vehicle 1000, or at the tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source or a power source for the vehicle 1000, etc. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for the starting, navigation and working power requirements of the vehicle 1000 during driving.

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

[0159] Please refer to Figure 2 and Figure 3 , Figure 2 The structure explosion diagram of the battery 100 provided in some embodiments of the present application is shown in FIG. Figure 3 The schematic diagram of the structure of the battery cell 20 provided in some embodiments of the present application is as follows. The battery 100 comprises a box body 10 and a battery cell 20 , and the battery cell 20 is used to be accommodated in the box body 10 .

[0160] The box body 10 is used to provide an assembly space for the battery cell 20, and the box body 10 can adopt a variety of structures. In some embodiments, the box body 10 may include a first box body 11 and a second box body 12, the first box body 11 and the second box body 12 cover each other, and the first box body 11 and the second box body 12 jointly define an assembly space for accommodating the battery cell 20. The second box body 12 may be a hollow structure with one end open, and the first box body 11 may be a plate-like structure, and the first box body 11 covers the open side of the second box body 12, so that the first box body 11 and the second box body 12 jointly define an assembly space; the first box body 11 and the second box body 12 may also be hollow structures with one side open, and the open side of the first box body 11 covers the open side of the second box body 12.

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

[0162] In the battery 100, the battery cell 20 disposed in the box 10 may be one or more. When there are more than one battery cell 20 disposed in the box 10, the multiple battery cells 20 may be connected in series, in parallel, or in mixed connection. Mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells 20 may be accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in mixed connection, and then the multiple battery modules may be connected in series, in parallel, or in mixed connection to form a whole, and then the whole may be accommodated in the box 10.

[0163] In some embodiments, the battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, which is used to connect the plurality of battery cells 20 to achieve electrical connection between the plurality of battery cells 20 .

[0164] Each battery cell 20 may be a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be in a rectangular parallelepiped, a cylinder, a prism or other shapes. For example, Figure 3 In the figure, the battery cell 20 is a rectangular parallelepiped 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 This is a structural explosion diagram of a battery cell 20 provided in some embodiments of the present application. Figure 5 A bottom view of the housing 21 of a battery cell 20 provided in some embodiments of the present application. Figure 6 A partial cross-sectional view of a housing 21 of a battery cell 20 provided in some embodiments of the present application. Figure 7 for Figure 6 A partial enlarged view of the A portion of the housing 21 shown. The embodiment of the present application provides a battery cell 20, the battery cell 20 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 arranged on the first wall 211. The pressure relief component 214 includes a first weak portion 2144, the first weak portion 2144 defines a predetermined pressure relief area 21431, and the pressure relief component 214 is configured to be able to split along at least a portion of the first weak portion 2144 when the battery cell 20 is depressurized. Among them, the pressure relief component 214 also includes a second weak portion 2145, and the second weak portion 2145 is configured to guide at least a portion of the predetermined pressure relief area 21431 to flip over to open at least a portion of the predetermined pressure relief area 21431.

[0166] The battery cell 20 refers to the smallest unit constituting the battery 100 .

[0167] The housing 21 includes an end cover 216 and a shell 215 . The shell 215 has an opening 2151 . The end cover 216 is connected to the shell 215 and closes the opening 2151 .

[0168] The end cap 216 refers to a component that covers the opening 2151 of the shell 215 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 216 can be adapted to the shape of the shell 215 to match the shell 215. Optionally, the end cap 216 can be made of a material with a certain hardness and strength (such as an aluminum alloy), so that the end cap 216 is not easily deformed when squeezed and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved. The material of the end cap 216 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose special restrictions on this. In some embodiments, the battery cell 20 also includes an insulating member, which is arranged on the inner side of the end cap 216. The insulating member can be used to isolate the electrical connection components in the shell 215 from the end cap 216 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc.

[0169] The shell 215 is a component used to cooperate with the end cap 216 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 22, the electrolyte and other components. The shell 215 and the end cap 216 can be independent components, and an opening 2151 can be set on the shell 215, and the end cap 216 is covered with the opening 2151 at the opening 2151 to form the internal environment of the battery cell 20. Without limitation, the end cap 216 and the shell 215 can also be integrated. Specifically, the end cap 216 and the shell 215 can form a common joint surface before other components are put into the shell, and when it is necessary to encapsulate the interior of the shell 215, the end cap 216 is covered with the shell 215. The shell 215 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 215 can be determined according to the specific shape and size of the electrode assembly 22. The shell 215 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0170] The electrode assembly 22 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 22 may be included in the housing 21. The electrode assembly 22 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly 22, and the parts of the positive and negative electrode sheets without active materials each constitute a tab 221. The positive tab and the negative tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery 100, the positive active material and the negative active material react with the electrolyte.

[0171] The first wall 211 may be an end cover 216 of the housing 21, or may be a wall of the shell 215 of the housing 21. Figure 3 and Figure 4 In the embodiment, the first wall 211 is a bottom wall of the housing 215 that is disposed opposite to the end cover 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 cover 216.

[0172] The pressure relief component 214 may be a component installed on the first wall 211, in which case the pressure relief component 214 is separately arranged and connected to the first wall 211. For example, the pressure relief component 214 is an explosion-proof disk installed on the first wall 211. The pressure relief component 214 may also be a part of the first wall 211, in which case the pressure relief component 214 is integrally formed with the first wall 211. The setting position 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 set on the end cover 216, the end cover 216 is the first wall 211. When the pressure relief component 214 is set on the bottom wall of the housing 215, the bottom wall is the first wall 211. When the pressure relief component 214 is set on the side wall of the housing 215, the side wall is the first wall 211.

[0173] The first weak portion 2144 serves to release pressure, and is used to enable the pressure relief component 214 to rupture along the first weak portion 2144 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, so as to release the pressure inside the battery cell 20. In some embodiments, the strength of the pressure relief component 214 at the position of the first weak portion 2144 may be lower than the strength of the pressure relief component 214 at other positions, so that when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, the first weak portion 2144 can rupture under the action of the internal pressure to release the pressure inside the battery cell 20. In other embodiments, the melting point of the pressure relief component 214 at the position of the first weak portion 2144 may be lower than the melting point of other positions of the pressure relief component 214. In this way, when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, the first weak portion 2144 can rupture under the action of high temperature to release the pressure inside the battery cell 20.

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

[0175] The second weak portion 2145 serves to guide at least a portion of the predetermined pressure relief area 21431 to flip open. Optionally, the second weak portion 2145 has a higher strength than the first weak portion 2144. When the battery cell 20 is depressurized, the first weak portion 2144 is first cracked to allow the fluid medium in the battery cell 20 to flow out and release pressure. Afterwards, the predetermined pressure relief area 21431 can flip outward with the second weak portion 2145 as the rotation axis under the action of the fluid medium to open a larger opening 2151 to achieve 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 is split to allow the fluid medium in 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 position of the second weak portion 2145 is weakened, so that the predetermined pressure relief area 21431 is more easily flipped open under the action of the fluid medium, which can not only increase the probability of the predetermined pressure relief area 21431 opening, but also increase the opening speed of the predetermined pressure relief area 21431, realize rapid pressure relief, reduce the risk of explosion and fire of the battery cell 20, and help improve the reliability of the battery cell 20.

[0177] In some embodiments, see Figure 4 As shown, the battery cell 20 may further include an electrode terminal 23 , which is insulated and mounted on the housing 21 , and is 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 installed on the housing 21 , that is, no electrical connection is formed between the electrode terminal 23 and the housing 21 .

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

[0180] Exemplarily, the electrode terminal 23 may be made of a variety of materials. For example, the electrode terminal 23 may be made of copper, iron, aluminum, steel, or aluminum alloy.

[0181] Optionally, the electrode terminal 23 may be mounted on the housing 21 in various structures. Figure 3 and Figure 4 In the embodiment, the two electrode terminals 23 are both mounted on the end cap 216 of the outer shell 21. Of course, the structure of the battery cell 20 is not limited thereto. In other embodiments, the two electrode terminals 23 may be both mounted on the shell 215 of the outer shell 21. Similarly, one electrode terminal 23 may be mounted on the shell 215 of the outer shell 21, and the other electrode terminal 23 may be mounted on the end cap 216 of the outer shell 21.

[0182] In some embodiments, see Figure 4 As shown, the battery cell 20 may also include two current collecting components 24, both of which are arranged in the outer shell 21, and each current collecting component 24 is used to connect an electrode terminal 23 and a plurality of electrode lugs 221 with the same polarity in the electrode assemblies 22 to achieve electrical connection between the electrode terminal 23 and the electrode assembly 22, which is beneficial to reduce the difficulty of assembly between the lug 221 and the electrode terminal 23.

[0183] Exemplarily, the material of the current collecting component 24 may be various, for example, the material of the current collecting component 24 may be 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 housing 21 includes a second wall 212 and a third wall 213 that are arranged opposite to each other along a first direction, and a first wall 211 connects the second wall 212 and the third wall 213. Along the first direction, the second wall 212 has a first outer surface 2121 that faces away from the interior of the housing 21, and the third wall 213 has a second outer surface 2131 that faces away from the interior of the housing 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 arranged 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 mutually connected walls of the housing 21, respectively, the first wall 211 and the third wall 213 are two adjacent and mutually connected walls of the housing 21, respectively, and the second wall 212 and the third wall 213 are two oppositely arranged walls of the housing 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 oppositely disposed side walls of the housing 215. When the first wall 211 is the side wall of the housing 215, the second wall 212 may be the end cover 216, and the third wall 213 may be the bottom wall of the housing 215.

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

[0189] Along the first direction, the second weak portion 2145 is disposed between the first weak portion 2144 and the first outer surface 2121. Alternatively, along the first direction, the second weak portion 2145 is disposed between the first weak portion 2144 and the second outer surface 2131. Alternatively, the pressure relief component 214 includes a plurality of second weak portions 2145, and along the first direction, a portion of the second weak portions 2145 is located between the first weak portion 2144 and the first outer surface 2121, and another portion of the second weak portions 2145 is 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 portions 2145. Along the first direction, one second weak portion 2145 is located between the first weak portion 2144 and the first outer surface 2121, and the other second weak portion 2145 is located between the first weak portion 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, and the stiffness at the location of the first weak portion 2144 is smaller than the stiffness at the location of the second weak portion 2145. When the battery cell 20 is depressurized, the deformation of the pressure relief component 214 at the location of the first weak portion 2144 is greater than the deformation of the pressure relief component 214 at the location of the second weak portion 2145, which is conducive to making the first weak portion 2144 crack before the second weak portion 2145, so that the predetermined pressure relief area 21431 can be flipped open under the guidance of the second weak portion 2145. Similarly, when a second weak portion 2145 is provided between the first weak portion 2144 and the second outer surface 2131, the second weak portion 2145 is closer to the second outer surface 2131 than the first weak portion 2144, and the stiffness at the location of the first weak portion 2144 is smaller than the stiffness at the location of the second weak portion 2145. When the battery cell 20 is depressurized, the deformation of the pressure relief component 214 at the location of the first weak portion 2144 is greater than the deformation of the pressure relief component 214 at the location of the second weak portion 2145, which is conducive to the first weak portion 2144 to crack before the second weak portion 2145, so that the predetermined pressure relief area 21431 can be flipped open under the guidance of the second weak portion 2145.

[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 the pressure relief component 214 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 section, and the pressure relief component 214 forms a weak section in the area where the groove section is provided. The cross-sectional area of ​​the weak section perpendicular to its extension direction is the first cross-sectional area, the minimum width of the groove bottom surface of the groove section is the first width, the minimum thickness of the weak section is the first thickness, and the first cross-sectional area is equal to the product of the first width and the first thickness. The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is the second cross-sectional area, the minimum width of the groove bottom surface of the second groove 21451 is the second width, the minimum thickness of the second weak portion 2145 is the 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 arranged on the same side of the pressure relief component 214, or on both 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 arranged opposite to each other, wherein the first surface 2111 faces away from the interior of the housing 21, and the second surface 2112 faces the interior of the housing 21. The first groove 2146 and the second groove 21451 can be both arranged on the first surface 2111, or both arranged on the second surface 2112, in which case the first groove 2146 and the second groove 21451 are arranged 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, cold heading, etc. Taking the stamping method to form 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 method to form 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 section, and the weak section is the bottom wall of the groove section. The weak sections correspond to the groove sections one by one.

[0195] The first weak portion 2144 includes at least one weak section, and the weak section is a linear structure. The first cross-sectional area represents the cross-sectional area of ​​the cross section perpendicular to the extension direction of the weak section. Figure 7 , Figure 7 The cross section perpendicular to the extension direction of the weak section is shown in the honeycomb filling pattern. The area filled by the honeycomb filling pattern is the first cross-sectional area, namely S1.

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

[0197] The first width is the minimum width of the bottom surface of the groove segment. Figure 7 , Figure 7 The first width is indicated in , and the first width is a1. It should be noted that the end of the slot segment generally adopts a rounded transition. When measuring the first width, the minimum width of the slot segment outside the rounded transition area should be measured, that is, the rounded transition position should be avoided for measurement.

[0198] The first thickness is the minimum thickness of the weak section. Figure 7 , Figure 7 The first thickness is indicated in , and the first thickness is h1. The first thickness can be obtained according to the difference between the thickness of the pressure relief component 214 and the depth of the groove section, or obtained by tomography, or measured after the weak section is cracked.

[0199] The first cross-sectional area is equal to the product of the first width and the first thickness, that is, S1=a1×h1. The first cross-sectional area can be calculated by measuring the first width and the first thickness. It should be noted that when obtaining the first cross-sectional area, the area where the groove section is rounded should be avoided.

[0200] The second weak portion 2145 may be a linear structure. The second cross-sectional area represents the cross-sectional area of ​​the cross section perpendicular to the extension direction of the second weak portion 2145. Figure 6 , Figure 6 2 shows a cross section perpendicular to the extension direction of the second weak portion 2145 with a mesh-like filling pattern. The area filled by the mesh-like filling pattern is the second cross-sectional area, that is, S2.

[0201] In some embodiments, the position of the second weak portion 2145 can be determined by tomography, and the cross-sectional area of ​​the cross section perpendicular to the extension direction of the second weak portion 2145 can be determined, that is, S2 can be obtained by tomography.

[0202] The second width is the minimum width of the bottom surface of the second groove 21451. Figure 6 , Figure 6 It should be noted that the end of the second groove 21451 generally adopts a rounded transition. When measuring the second width, the minimum width of the second groove 21451 outside the rounded transition area should be measured, that is, the rounded transition position should be avoided for measurement.

[0203] The second thickness is the minimum thickness of the second weak portion 2145. Figure 6 , Figure 6 The second thickness is indicated in , and the second thickness is h2. The second thickness can be obtained according to the difference between the thickness of the pressure relief component 214 and the depth of the second groove 21451, or obtained by tomography, or obtained by measuring after cutting open the second weak portion 2145.

[0204] The second cross-sectional area is equal to the product of the second width and the second thickness, that is, S2=a2×h2. The second cross-sectional area can be calculated by measuring the second width and the second thickness. It should be noted that when obtaining the second cross-sectional area, the area where the second notch groove is rounded should be avoided.

[0205] The first weak portion 2144 and the second weak portion 2145 are formed by providing the first groove 2146 and the second groove 21451 on the pressure relief component 214, which is simple, convenient and low in 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 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 obtain the first cross-sectional area. The second cross-sectional area is equal to the product of the second width and the second thickness, that is, the cross section of the second weak portion 2145 perpendicular to its extension direction is rectangular. When measuring the second cross-sectional area, the second width and the second thickness can be measured to obtain 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, satisfying: 0.01 mm ≤ a1 ≤ 0.8 mm.

[0207] The value of the first width can be a1=0.01mm, 0.03mm, 0.05mm, 0.08mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, etc.

[0208] When a1≥0.01mm, the first width is relatively large, which can reduce the risk of the weak section cracking due to changes in the air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When a1≤0.8mm, the first width is not too large, which is beneficial to the weak section to crack in time when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20. Therefore, when 0.01mm≤a1≤0.8mm, the first width is moderate, the weak section is not easy to crack due to changes in the air pressure inside the battery cell 20, and can be cracked in time when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20.

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

[0210] The value of the first width can be a1=0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.42mm, 0.45mm, 0.48mm, 0.5mm, etc.

[0211] When a1≥0.05mm, the first width is larger, which can further reduce the risk of the weak section being cracked due to the change in air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When a1≤0.5mm, it is beneficial to make the weak section crack more timely when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure release of the battery cell 20. Therefore, when 0.05mm≤a1≤0.5mm, the reliability and timeliness of the pressure release of the battery cell 20 are better taken into account.

[0212] Optionally, 0.1mm≤a1≤0.3mm.

[0213] The value of 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≥0.1mm, the first width is larger, which can further reduce the risk of the weak section being cracked due to the change in air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When a1≤0.3mm, it is beneficial to make the weak section crack more timely when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure release of the battery cell 20. Therefore, when 0.1mm≤a1≤0.3mm, the reliability and timeliness of the pressure release of the battery cell 20 are better taken into account.

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

[0216] The value of the first thickness can be h1=0.02mm, 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, etc.

[0217] When h1≥0.02mm, the first thickness is relatively large, which can reduce the risk of the weak section cracking due to changes in the air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When h1≤1mm, the first thickness is not too large, which is beneficial to the weak section to crack in time when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20. Therefore, when 0.02mm≤h1≤1mm, the first thickness is moderate, the weak section is not easy to crack due to changes in the air pressure inside the battery cell 20, and can be cracked in time when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20.

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

[0219] The value of the first thickness can be h1=0.04mm, 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.42mm, 0.45mm, 0.48mm, 0.5mm, 0.52mm, 0.55mm, 0.58mm, 0.6mm, etc.

[0220] When h1≥0.04mm, the first thickness is larger, which can further reduce the risk of the weak section being cracked due to the change in air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When h1≤0.6mm, it is beneficial to make the weak section crack more timely when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the pressure release of the battery cell 20. Therefore, when 0.04mm≤h1≤0.6mm, the reliability and timeliness of the pressure release of the battery cell 20 are better taken into account.

[0221] Optionally, 0.08mm≤h1≤0.4mm.

[0222] The value of the first thickness can be h1=0.08mm, 0.09mm, 0.1mm, 0.11m, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, 0.4mm, etc.

[0223] When h1≥0.08mm, the first thickness is larger, which can further reduce the risk of the weak section being cracked due to the change in air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When h1≤0.4mm, it is beneficial to make the weak section crack more timely when the battery cell 20 is depressurized, which is beneficial to improving the timeliness of the depressurization of the battery cell 20. Therefore, when 0.08mm≤h1≤0.4mm, the reliability and timeliness of the depressurization of the battery cell 20 are better taken into account.

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

[0225] The value of the second width can be a2 = 0.01 mm, 0.03 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, etc.

[0226] When a2≥0.01mm, the second width is relatively large, which can reduce the risk of the second weak portion 2145 cracking due to changes in the air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When a2≤0.5mm, the second width is not too large, which is beneficial to reducing 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 the pressure relief of the battery cell 20. Therefore, when 0.01mm≤a2≤0.5mm, the second width is moderate, the second weak portion 2145 is not easily cracked due to changes in the air pressure inside the battery cell 20, and is convenient for the predetermined pressure relief area 21431 to be quickly flipped and opened, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20.

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

[0228] The value of the second width can be a2 = 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11m, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, etc.

[0229] When a2≥0.04mm, the second width is larger, which can further reduce the risk of the second weak portion 2145 cracking due to the change in air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When a2≤0.3mm, the resistance to the flipping of the predetermined pressure relief area 21431 is smaller, which facilitates the rapid flipping and opening of the predetermined pressure relief area 21431, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20. Therefore, when 0.04mm≤a2≤0.3mm, the reliability and timeliness of the pressure relief of the battery cell 20 are better taken into account.

[0230] Optionally, 0.06mm≤a2≤0.15mm.

[0231] The value of the second width can be a2 = 0.06mm, 0.065mm, 0.07mm, 0.075mm, 0.08mm, 0.085mm, 0.09mm, 0.095mm, 0.1mm, 0.105mm, 0.11m, 0.115mm, 0.12mm, 0.125mm, 0.13mm, 0.135mm, 0.14mm, 0.145mm, 0.15mm.

[0232] When a2≥0.06mm, the second width is larger, which can further reduce the risk of the second weak portion 2145 cracking due to the change in air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When a2≤0.15mm, the resistance to the flipping of the predetermined pressure relief area 21431 is smaller, which facilitates the rapid flipping and opening of the predetermined pressure relief area 21431, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20. Therefore, when 0.06mm≤a2≤0.15mm, the reliability and timeliness of the pressure relief of the battery cell 20 are better taken into account.

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

[0234] The value of the second thickness can be h2 = 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, etc.

[0235] When h2≥0.1mm, the second thickness is relatively large, which can reduce the risk of the second weak portion 2145 cracking due to changes in the air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When h2≤2mm, the second thickness is not too large, which is beneficial to reducing 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 the pressure relief of the battery cell 20. Therefore, when 0.1mm≤h2≤2mm, the second thickness is moderate, the second weak portion 2145 is not easily cracked due to changes in the air pressure inside the battery cell 20, and is convenient for the rapid flipping and opening of the predetermined pressure relief area 21431, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20.

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

[0237] The value of the second thickness can be h2 = 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, etc.

[0238] When h2≥0.2mm, the second thickness is larger, which can further reduce the risk of the second weak portion 2145 cracking due to the change in air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When h2≤1.5mm, the resistance to the flipping of the predetermined pressure relief area 21431 is smaller, which facilitates the rapid flipping and opening of the predetermined pressure relief area 21431, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20. Therefore, when 0.2mm≤h2≤1.5mm, the reliability and timeliness of the pressure relief of the battery cell 20 are better taken into account.

[0239] Optionally, 0.5mm≤h2≤1mm.

[0240] The value of the second thickness can be h2 = 0.5mm, 0.52mm, 0.55mm, 0.58mm, 0.6mm, 0.62mm, 0.65mm, 0.68mm, 0.7mm, 0.72mm, 0.75mm, 0.78mm, 0.8mm, 0.82mm, 0.85mm, 0.88mm, 0.9mm, 0.92mm, 0.95mm, 0.98mm, 1mm, etc.

[0241] When h2≥0.5mm, the second thickness is larger, which can further reduce the risk of the second weak portion 2145 cracking due to the change in air pressure inside the battery cell 20, which is beneficial to improving the reliability of the battery cell 20. When h2≤1mm, the resistance to the flipping of the predetermined pressure relief area 21431 is smaller, which facilitates the rapid flipping and opening of the predetermined pressure relief area 21431, which is beneficial to improving the timeliness of pressure relief of the battery cell 20. Therefore, when 0.5mm≤h2≤1mm, the reliability and timeliness of pressure relief of the battery cell 20 are better taken into account.

[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 a first distance, the minimum distance between the first weak portion 2144 and the first outer surface 2121 is a second distance, the minimum distance between the first weak portion 2144 and the second outer surface 2131 is a third distance, and the ratio of the difference between the second distance and the third distance to the first distance is greater than or equal to 0 and less than or equal to 0.1.

[0243] The first distance represents the distance between the first outer surface 2121 and the second outer surface 2131 along the first direction. Figure 5 , the figure shows the first distance, which is L. During measurement, multiple measurements can be taken to obtain an average value.

[0244] The second distance represents the minimum distance between the first weak portion 2144 and the first outer surface 2121 along the first direction. Figure 5 , the second distance is indicated in the figure, and the second distance is L1. During measurement, the distance between the position of the first weak portion 2144 closest to the first outer surface 2121 and the first outer surface 2121 can be measured, and multiple measurements can also be taken to obtain an average value to reduce measurement errors.

[0245] The third distance represents the minimum distance between the first weak portion 2144 and the second outer surface 2131 along the first direction. Figure 5, the third distance is indicated in the figure, and the second distance is L2. During measurement, the distance between the position of the first weak portion 2144 closest to the second outer surface 2131 and the second outer surface 2131 can be measured, and multiple measurements can also be taken to obtain an average value to reduce measurement errors.

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

[0247] “The ratio of the difference between the second distance and the third distance to the first distance is greater than or equal to 0 and less than or equal to 0.1”, that is, 0≤|L1-L2| / L≤0.1.

[0248] 0≤|L1-L2| / L≤0.1 indicates that the distance from the first weak portion 2144 to the first outer surface 2121 and the distance from the first weak portion 2144 to the second outer surface 2131 are slightly different, that is, the first weak portion 2144 is approximately 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 portion 2144 is close to the middle position of the first wall 211 along the first direction. The stiffness of the middle position of the first wall 211 along the first direction is relatively small. When the battery cell 20 is depressurized, the middle position of the first wall 211 along the first direction will undergo a large deformation, which is conducive to the first weak portion 2144 to crack before the second weak portion 2145, so that the predetermined pressure relief area 21431 can be flipped open under the guidance of the second weak portion 2145, which is conducive to improving the reliability of the battery cell 20.

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

[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. The first direction intersects with the thickness direction of the first wall 211. Figure 6 and Figure 7 In the illustrated embodiment, 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 that are oppositely arranged, wherein the first surface 2111 faces away from the interior of the housing 21, and the second surface 2112 faces the interior of the housing 21. When the pressure relief component 214 and the first wall 211 are integrally formed, the first surface 2111 is the third outer surface 2113 mentioned above.

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

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

[0257] Please refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7In some embodiments, 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 the first distance, the minimum distance between the second weak portion 2145 and the first outer surface 2121 is the fourth distance, and the minimum distance between the second weak portion 2145 and the second outer surface 2131 is the fifth distance. The first weak portion 2144 includes at least one weak section, the cross-sectional area of ​​the weak section perpendicular to the extension direction thereof is the first cross-sectional area, the cross-sectional area of ​​the second weak portion 2145 perpendicular to the extension direction thereof is the second cross-sectional area, and 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 portion 2145 and the first outer surface 2121 along the first direction. Figure 5 , the fourth distance is marked in the figure, and the fourth distance is L3. When measuring, the distance between the position of the second weak portion 2145 closest to the first outer surface 2121 and the first outer surface 2121 can be measured, and the average value can be taken by multiple measurements to reduce the measurement error.

[0259] The fifth distance represents the minimum distance between the second weak portion 2145 and the second outer surface 2131. Figure 5 , the fifth distance is marked in the figure, and the fifth distance is L4. When measuring, the distance between the position of the second weak portion 2145 closest to the second outer surface 2131 and the second outer surface 2131 can be measured, and the average value can be taken by multiple measurements to reduce the measurement error.

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

[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 portion 2145 to the first outer surface 2121 and the distance from the second weak portion 2145 to the second outer surface 2131 are greatly different, that is, the second weak portion 2145 is set away from the middle position of the first wall 211, and the second weak portion 2145 is close to the first outer surface 2121.

[0262] The first weak portion 2144 includes at least one weak section, and the weak section is a linear structure. S1 represents the cross-sectional area of ​​the cross section perpendicular to the extension direction of the weak section. The cross-sectional area of ​​the weak section perpendicular to its extension direction has a significant impact on whether the weak section is easy to split. The larger the cross-sectional area of ​​the weak section perpendicular to its extension direction, the more difficult it is for the weak section to split. The smaller the cross-sectional area of ​​the weak section perpendicular to its extension direction, the easier it is for the weak section to split.

[0263] The second weak portion 2145 may be a linear structure. S2 represents the cross-sectional area of ​​the cross section perpendicular to the extension direction of the second weak portion 2145. The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction has a significant impact on whether the second weak portion 2145 is easy to crack. The larger the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction, the more difficult it is for the second weak portion 2145 to crack. The smaller the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction, the easier it is for the second weak portion 2145 to crack.

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

[0265] When |L4-L3| / L≥0.4, the value of S2 / S1 can be: S2 / S1=0.71, 0.75, 0.78, 0.8, 0.83, 0.85, 0.9, 0.93, 0.95, 1, 1.05, 1.11, 1.12, 1.15, 1.17, 1.2, 1.24, 1.25, 1.3, 1.35, 1.38, 1.4, 1.44, 1.47, 1.5, etc.

[0266] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail in combination with Comparative Examples 1-6 and Examples 1-17. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0267] Example 1

[0268] 1) Preparation of positive electrode

[0269] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are used to prepare positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the solid content of LiNi 0.7 Co 0.1 Mn 0.1 The mass ratio of O2, Super P and PVDF is 8:1:1. The positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil and dried at 85°C and then cold pressed. Then, it is trimmed, cut and stripped, and then dried at 85°C under vacuum conditions for 4 hours to make the positive electrode sheet.

[0270] 2) Preparation of negative electrode

[0271] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry is 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC and adhesive styrene butadiene rubber (SBR) in the solid component 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, and then cold pressed, trimmed, cut into pieces, and slit, and then dried at 120°C under vacuum conditions for 12 hours to prepare a negative electrode sheet.

[0272] 3) Preparation of electrolyte

[0273] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), the fully dried electrolyte salt LiPF6 was dissolved in a mixed solvent (the mixed solvent included ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 50:50), and after mixing evenly, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0274] 4) Isolation parts

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

[0276] 5) Preparation of battery cell 20

[0277] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is located between the positive and negative electrode sheets to isolate the positive and negative electrodes, and the electrode assembly 22 is wound, and the electrode assembly 22 is placed in an aluminum shell 21, and the prepared electrolyte is injected into the dried shell 21, and the battery cell 20 is prepared, and a first weak portion 2144 and a second weak portion 2145 are formed on the first wall 211 of the shell 21 of the battery cell 20, wherein the embodiment 1 The outer shell 21 of the battery cell 20 is a rectangular parallelepiped structure, the shell 215 of the outer shell 21 is a structure with an opening 2151 formed at one end, the wall of the shell 215 opposite to the end cover 216 is a first wall 211, the first wall 211 is a rectangular wall, a first groove 2146 and a second groove 21451 are provided on the first wall 211, the first wall 211 forms a first weak portion 2144 in the area where the first groove 2146 is provided, and the first wall 211 forms a second weak portion 2145 in the area where the second groove 21451 is provided. Along the first direction, the second weak portion 2145 is provided between the first weak portion 2144 and the first outer surface 2121. Among them, the first groove 2146 is an "H"-shaped structure, that is, the first groove 2146 includes a first groove section 2143a, a second groove section 2143b and a third groove section 2143c, the first groove section 2143a and the third groove section 2143c are arranged opposite to each other and both extend along the first direction, the second groove section 2143b is connected between the first groove section 2143a and the third groove section 2143c, and the second groove section 2143b is located in the middle of the first wall 211 in the first direction, the thickness of the battery cell 20 is 39mm, the width is 203mm, the shoulder height (the dimension of the shell 21 in the height direction) is 122.7mm, and the capacity is 185Ah.

[0278] For the distance L between the first outer surface 2121 and the second outer surface 2131, the minimum distance L3 between the second weak portion 2145 and the first outer surface 2121, the minimum distance L4 between the second weak portion 2145 and the second outer surface 2131, the width D of the groove bottom surface of the groove segment 1、 The thickness H1 of the weak section, the width D2 of the bottom surface of the second groove 21451 and the thickness H2 of the second weak portion 2145 are all obtained by tomography and then measured by software.

[0279] The preparation methods of the battery cells 20 of comparative examples 1 to 4 and embodiments 2 to 10 are the same as those of embodiment 1, except that the difference between the minimum distance L4 between the second weak portion 2145 and the second outer surface 2131 and the minimum distance L3 between the second weak portion 2145 and the first outer surface 2121, the cross-sectional area S1 of the weak section perpendicular to its extension direction and the cross-sectional area S2 of the second weak portion 2145 perpendicular to its extension direction are different. In comparative examples 1 to 4 and embodiments 1 to 10, the first direction is the width direction of the first wall 211, and the specific situation is shown in Tables 1 to 2.

[0280] The preparation methods of the battery cells 20 of comparative examples 5 to 6 and embodiments 11 to 17 are the same as those of embodiment 1, except that the difference between the minimum distance L4 between the second weak portion 2145 and the second outer surface 2131 and the minimum distance L3 between the second weak portion 2145 and the first outer surface 2121, the cross-sectional area S1 of the weak section perpendicular to its extension direction and the cross-sectional area S2 of the second weak portion 2145 perpendicular to its extension direction are different. In comparative examples 5 to 6 and embodiments 11 to 17, the first direction is the length direction of the first wall 211, and the specific situation is shown in Table 3.

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

[0282] During the blasting experiment, a steel clamp is 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, to simulate the restraint state of the battery cell 20 in a real module or battery pack; at the same time, during the experiment, the pressure relief component 214 is filmed throughout the process to observe its detonation position and the flipping action of the predetermined pressure relief area 21431. Before the experiment, the detonation pressure test system and the battery cell 20 are connected through a hose; during the experiment, the detonation pressure test system inflates and blasts the battery cell 20 at 0.3MPa / s, and detects the intake pressure of the battery cell 20 in real time. When the intake pressure drops by more than 0.02MPa, the inflation is stopped. In general, the intake pressure curve generally shows an increasing trend. When the intake pressure reaches the detonation pressure of the battery cell 20, it will suddenly drop to 0. At this time, the maximum value of the curve is the detonation pressure of the battery cell 20.

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

[0284] Table 1

[0285]

[0286]

[0287] Table 2

[0288]

[0289] Table 3

[0290]

[0291] Please refer to Tables 1 and 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 portion 2145 perpendicular to its extension direction is small. When the battery cell 20 is depressurized, the second weak portion 2145 cracks before the first weak portion 2144.

[0292] As shown in Comparative Examples 2 and 4, |L4-L3| / L≥0.4, but S2 / S1>1.5. At this time, the second weak portion 2145 is close to the first outer surface 2121, and the stiffness of the first wall 211 at the second weak portion 2145 is quite different from the stiffness of the first wall 211 at the first weak portion 2144. The stiffness has a greater influence on the cracking of the first weak portion 2144 and the second weak portion 2145. In addition, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is larger, and the strength of the pressure relief component 214 at the second weak portion 2145 is greater, which greatly hinders the predetermined pressure relief area 21431 from flipping open, making it difficult for the predetermined pressure relief area 21431 to flip open under the action of the fluid medium. In the project, it is expected that the detonation position of the pressure relief component 214 is located at the first weak portion 2144, and the second weak portion 2145 only serves as a guide. When the battery cell 20 is used in 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 portion 2144, but also enables the detonation pressure to meet engineering expectations.

[0294] When |L4-L3| / L≥0.4, the second weak portion 2145 deviates from the middle position of the first wall 211 along the width direction of the first wall 211 by a large distance. At this time, the second weak portion 2145 is close to the first outer surface 2121. The stiffness of the first wall 211 at the second weak portion 2145 is greatly different from the stiffness of the first wall 211 at 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. If the impact of the stiffness on the first weak portion 2144 and the second weak portion 2145 is not considered, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction only needs to be greater than the cross-sectional area of ​​the weak section perpendicular to its extension direction, that is, S2 / S1>1, so that the first weak portion 2144 opens to release pressure before the second weak portion 2145, and the second weak portion 2145 plays a guiding role in the predetermined pressure relief area 21431. However, considering that the rigidity has a greater impact on the splitting of the first weak portion 2144 and the second weak portion 2145 (under the same cross-sectional area, the second weak portion 2145 is more difficult to split than the first weak portion 2144, so the cross-sectional area of ​​the second weak portion 2145 can be set smaller), when 0.7<S2 / S1≤1, the first weak portion 2144 can also be opened to release pressure before the second weak portion 2145, and the second weak portion 2145 plays a guiding role in the predetermined pressure relief area 21431. Similarly, since the rigidity has a greater impact on the splitting of the first weak portion 2144 and the second weak portion 2145, when S2 / S1≤1.5, the strength of the pressure relief component 214 at the position of the second weak portion 2145 is smaller, and the obstacle to the flipping and opening of the predetermined pressure relief area 21431 is smaller, making it easier for the predetermined pressure relief area 21431 to flip and 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 facing away from the interior of the housing 21, the third outer surface 2113 is rectangular, and the first direction is parallel to the width direction of the rectangle.

[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, and the second weak portion 2145 is closer to the edge position of the first wall 211 along the width direction than the first weak portion 2144. The stiffness has a greater influence 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 area where the first groove 2146 is provided, 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 2146 includes at least one groove section, and the pressure relief component 214 forms a weak section in the area where the groove section is provided. The cross-sectional area of ​​the weak section perpendicular to its extension direction is the first cross-sectional area, the minimum width of the groove bottom surface of the groove section is the first width, the minimum thickness of the weak section is the first thickness, and the first cross-sectional area is equal to the product of the first width and the first thickness. The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is the second cross-sectional area, the minimum width of the groove bottom surface of the second groove 21451 is the second width, the minimum thickness of the second weak portion 2145 is the second thickness, and the second cross-sectional area is equal to the product of the second width and the second thickness. The second thickness is greater than or equal to the first thickness, and the second width is less than or equal to the first width.

[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” means h2≥h1, 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 portion 2145 better guide the predetermined pressure relief zone 21431 to open, but also the second width can be made as small as possible under the condition that when the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1.5, thereby reducing the area occupied by the second groove 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, 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 the first distance, the minimum distance between the second weak portion 2145 and the first outer surface 2121 is the fourth distance, and the minimum distance between the second weak portion 2145 and the second outer surface 2131 is the fifth distance. The first weak portion 2144 includes at least one weak section, the cross-sectional area of ​​the weak section perpendicular to the extension direction thereof is the first cross-sectional area, the cross-sectional area of ​​the second weak portion 2145 perpendicular to the extension direction thereof is the second cross-sectional area, and 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 value of S2 / S1 can be: S2 / S1=1.53, 1.71, 1.8, 1.82, 1.83, 2, 2.13, 2.2, 2.5, 2.56, 2.8, 3, 3.31, 3.2, 3.4, 3.5, 3.8, 4, 4.08, 4.2, 4.5, 4.67, 4.8, 4.75, 5, etc.

[0304] Please refer to Table 3. As shown in Comparative Example 5, |L4-L3| / L<0.4, S2 / S1≤1.5. At this time, the second weak portion 2145 is close to the middle position of the first outer surface 2121. The stiffness of the first wall 211 at the second weak portion 2145 is slightly different from the stiffness of the first wall 211 at the first weak portion 2144. The stiffness has little effect on the cracking of the first weak portion 2144 and the second weak portion 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] Please refer to Table 3. As shown in Comparative Example 6, |L4-L3| / L<0.4, S2 / S1>5. At this time, the second weak portion 2145 is close to the middle position of the first outer surface 2121. The stiffness of the first wall 211 at the second weak portion 2145 is slightly different from the stiffness of the first wall 211 at the first weak portion 2144. The stiffness has little effect on the cracking of the first weak portion 2144 and the second weak portion 2145. However, at this time, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is too large, and the strength of the pressure relief component 214 at the second weak portion 2145 is too large, which greatly hinders the predetermined pressure relief area 21431 from flipping open, making it difficult for the predetermined pressure relief area 21431 to flip open under the action of the fluid medium. In the project, it is expected that the detonation position of the pressure relief component 214 is located at the first weak portion 2144, and the second weak portion 2145 only serves as a guide. When the battery cell 20 is used in a project, there is an upper and lower limit requirement for the detonation pressure (0.9±0.2MPa). 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 portion 2144, but also enables the detonation pressure to meet engineering expectations.

[0307] When |L4-L3| / L<0.4, the distance of the second weak portion 2145 from the middle 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 middle 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 slightly different from the stiffness of the first wall 211 at the position of the first weak portion 2144. The stiffness has little effect 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 be opened to release pressure before the second weak portion 2145. The second weak portion 2145 plays a guiding role in the predetermined pressure relief area 21431, reducing the risk of the second weak portion 2145 cracking before the first weak portion 2144. When S2 / S1≤5, the strength of the pressure relief component 214 at the second weak portion 2145 is relatively small, and the obstacle to the predetermined pressure relief area 21431 flipping open is relatively small, making it easier for the predetermined pressure relief area 21431 to flip open under the action of the fluid medium.

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

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

[0311] In some embodiments, a ratio of the second cross-sectional area to the first cross-sectional area is greater than or equal to 2.13 and less than or equal to 4.67.

[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”, that is, when |L4-L3| / L<0.4, 2.13≤S2 / S1≤4.67.

[0313] When |L4-L3| / L<0.4, the value of S2 / S1 can be: S2 / S1=2.13, 2.15, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.67, etc.

[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 portion 2144, but also allows the detonation pressure to be closer to 0.9 MPa.

[0315] When S2 / S1≥2.13, the first weak portion 2144 can be opened and depressurized before the second weak portion 2145, and the second weak portion 2145 guides the predetermined pressure relief area 21431, further reducing the risk of the second weak portion 2145 cracking before the first weak portion 2144. When S2 / S1≤4.67, the strength of the pressure relief component 214 at the second weak portion 2145 is smaller, and the obstacle to the predetermined pressure relief area 21431 flipping open is smaller, making it easier for the predetermined pressure relief area 21431 to flip 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 area where the first groove 2146 is provided, 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 2146 includes at least one groove section, and the pressure relief component 214 forms a weak section in the area where the groove section is provided. The cross-sectional area of ​​the weak section perpendicular to its extension direction is the first cross-sectional area, the minimum width of the groove bottom surface of the groove section is the first width, the minimum thickness of the weak section is the first thickness, and the first cross-sectional area is equal to the product of the first width and the first thickness. The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is the second cross-sectional area, the minimum width of the groove bottom surface of the second groove 21451 is the second width, the minimum thickness of the second weak portion 2145 is the second thickness, and the second cross-sectional area is equal to the product of the second width and the second thickness. The second thickness is greater than or equal to the first thickness, and the second width is greater than or equal to the first width.

[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” means h2≥h1, 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 the stiffness variation of different regions of the first wall 211 on the cracking of the weak section and the second weak section 2145 can be further reduced, so that the weak section cracks when the battery cell 20 is depressurized, and the second weak section 2145 guides the flipping of the predetermined pressure relief area 21431. In some embodiments, the first cross-sectional area is S1, which satisfies: 0.0002mm 2 ≤S1≤0.8mm 2 .

[0319] The cross-sectional area of ​​the weak section perpendicular to its extension direction can be: S1 = 0.0002 mm 2 、0.0005mm 2 、0.001mm 2 、0.0015mm 2 、0.002mm 2 、0.003mm 2 、0.005mm 2 , 0.01mm 2 , 0.03mm 2 , 0.05mm 2 、0.08mm 2 , 0.1mm 2 , 0.15mm2 , 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≥0.0002mm 2 When S1≤0.8mm, the cross-sectional area of ​​the first weak section perpendicular to its extension direction is large, and it is not easy to crack when subjected to external impact, which is beneficial to improving the reliability of the battery cell 20. 2 When the cross-sectional area of ​​the first weak section perpendicular to its extension direction is not too large, when the internal pressure of the battery cell 20 reaches the detonation pressure, the first weak section is easy to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.8mm 2 , which can take into account both resistance to external impact and easy opening of pressure relief when the internal pressure of the battery cell 20 reaches the detonation 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: 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≥0.002mm 2 When S1≤0.3mm, the risk of the first weak section cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell 20. 2 When the internal pressure of the battery cell 20 reaches the detonation pressure, the first weak section is more likely to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.3mm 2 When the battery cell 20 is in the state of being in a ...

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

[0325] The cross-sectional area of ​​the weak section perpendicular to its extension direction can be: S1 = 0.008 mm 2 、0.009mm 2 , 0.01mm 2 、0.015mm 2 , 0.02mm 2 , 0.025mm 2 , 0.03mm 2 、0.035mm 2 , 0.04mm 2 、0.045mm 2 , 0.05mm 2 、0.055mm 2 , 0.06mm 2 , 0.07mm 2 , 0.075mm 2 、0.08mm 2 、0.085mm 2 、0.09mm 2 , 0.1mm 2 , 0.105mm 2 、0.11mm 2 , 0.115mm 2 , 0.12mm 2 wait.

[0326] When S1≥0.008mm 2 When S1≤0.12mm, the risk of the first weak section cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell 20.2 When the internal pressure of the battery cell 20 reaches the detonation pressure, the first weak section is more likely to rupture under the action of the fluid medium to achieve pressure relief. 2 ≤S1≤0.12mm 2 When the battery cell 20 is in the state of being in a ...

[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 portion 2145 perpendicular to its extension direction can be: S2 = 0.001 mm 2 、0.0015mm 2 、0.002mm 2 、0.003mm 2 、0.005mm 2 , 0.01mm 2 , 0.03mm 2 , 0.05mm 2 、0.08mm 2 , 0.1mm 2 , 0.15mm 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≥0.001mm 2 When S2≤1mm, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is large, and it is not easy to crack when subjected to external impact, which is beneficial to improving the reliability of the battery cell 20. 2When the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction is not too large, it is helpful to reduce the resistance of the predetermined pressure relief area 21431 to flip over, and facilitate the predetermined pressure relief area 21431 to flip over and open quickly. 2 ≤S2≤1mm 2 , which can take into account both resisting external impact and facilitating the rapid flipping and opening of the predetermined pressure relief area 21431.

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

[0331] The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction can be: S2 = 0.008 mm 2 、0.009mm 2 , 0.01mm 2 , 0.03mm 2 , 0.05mm 2 、0.08mm 2 , 0.1mm 2 , 0.13mm 2 , 0.15mm 2 , 0.18mm 2 , 0.2mm 2 , 0.22mm 2 , 0.25mm 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≥0.008mm 2 When S2≤0.45mm, the risk of the second weak portion 2145 cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell 20. 2 , the resistance to the predetermined pressure relief area 21431 turning over is smaller, which facilitates the predetermined pressure relief area 21431 to turn over and open quickly. 2 ≤S2≤0.45mm 2 When the pressure relief area 21431 is opened, it can better resist external impact and facilitate quick flipping and opening of the predetermined pressure relief area 21431.

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

[0334] The cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction can be: S2 = 0.03 mm 2 、0.035mm 2 , 0.04mm 2 、0.045mm 2 , 0.05mm 2 、0.055mm 2 , 0.06mm 2 、0.065mm 2 , 0.07mm 2 , 0.075mm 2 、0.08mm 2 、0.085mm 2 、0.09mm 2 、0.095mm 2 , 0.1mm 2 , 0.105mm 2 、0.11mm 2 、0.115mm 2 , 0.12mm 2 , 0.125mm 2 , 0.13mm 2 , 0.135mm 2 , 0.14mm 2 , 0.145mm 2 , 0.15mm 2 wait.

[0335] When S2≥0.03mm 2 When S2≤0.15mm, the risk of the second weak portion 2145 cracking when subjected to external impact can be further reduced, which is beneficial to improving the reliability of the battery cell 20. 2 , the resistance to the predetermined pressure relief area 21431 turning over is smaller, which facilitates the predetermined pressure relief area 21431 to turn over and open quickly. 2 ≤S2≤0.15mm 2 When the pressure relief area 21431 is opened, it can better resist external impact and facilitate quick flipping and opening. 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 provided with the second groove 21451. The second groove 21451 is provided on the surface of the pressure relief component 214 facing the inside 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 oppositely disposed, wherein the first surface 2111 faces away from the interior of the housing 21 and the second surface 2112 faces the interior of the housing 21 . The second groove 21451 is disposed on the second surface 2112 .

[0337] The second groove 21451 can be formed by various methods, such as stamping, cold heading, etc. For example, the second groove 21451 can be formed by stamping on the pressure relief component 214 along the direction from the second surface 2112 to the first surface 2111.

[0338] The second groove 21451 is formed by stamping or cold heading, so that the groove wall of the second groove 21451 undergoes cold work hardening (the grain arrangement changes, resulting in lattice distortion, which reduces the metal plasticity and increases the material hardness), and its ability to resist external impact is enhanced, and it is not easily damaged by external impact. In this way, the risk of leakage of the pressure relief component 214 is reduced.

[0339] The second weak portion 2145 is formed by providing the second groove 21451 on the pressure relief component 214, which is simple, convenient and low in cost. In addition, the second groove 21451 is provided on the surface of the pressure relief component 214 facing the inside of the housing 21, and the tension that the predetermined pressure relief area 21431 needs to overcome when flipping is small, so that the predetermined pressure relief area 21431 can be quickly flipped open, which is beneficial to improving 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 that are oppositely disposed 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 area 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 area 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 a portion of the pressure relief component 214 located between the bottom surface of the first groove 2146 farthest from the first surface 2111 and the second surface 2112. The second weak portion 2145 is a portion of the pressure relief component 214 located between the bottom surface of the second groove 21451 farthest from the second surface 2112 and the first surface 2111.

[0343] The first groove 2146 can be formed by various methods, such as stamping, cold heading, etc. For example, the first groove 2146 can be formed by stamping on the pressure relief component 214 along the direction from the first surface 2111 to the second surface 2112 .

[0344] The first groove 2146 is formed by stamping or cold heading, so that the groove wall of the first groove 2146 undergoes cold work hardening (the grain arrangement changes, resulting in lattice distortion, which reduces the metal plasticity and increases the material hardness), and its ability to resist external impact is enhanced, and it is not easily damaged by external impact. In this way, the risk of leakage of the pressure relief component 214 is reduced.

[0345] The first weak portion 2144 and the second weak portion 2145 are formed by providing the first groove 2146 and the second groove 21451 on the pressure relief component 214, which is simple, convenient and low in cost. The first groove 2146 and the second groove 21451 are respectively provided on the first surface 2111 and the second surface 2112 of the pressure relief component 214, so that the first groove 2146 and the second groove 21451 are respectively located on both sides of the pressure relief component 214, thereby facilitating the processing of the first groove 2146 and the second groove 21451 on both sides of the pressure relief component 214, and facilitating the mutual influence of the first groove 2146 and the second groove 21451 during the processing.

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

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

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

[0349] By arranging the first groove 2146 on the surface of the pressure relief component 214 facing away from the inside of the housing 21, the first weak portion 2144 has less tension to overcome when cracking, and is easy to crack. By arranging the second groove 21451 on the surface of the pressure relief component 214 facing the inside of the housing 21, the predetermined pressure relief area 21431 has less tension to overcome when flipping, so that the predetermined pressure relief area 21431 can be quickly flipped open, which is beneficial to improving the reliability of the battery cell 20.

[0350] Please refer to Fig. 9 , Fig. 9 A bottom view of the housing 21 of the battery cell 20 provided in some other embodiments of the present application. In some other embodiments, the 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 section 2143a and a second groove section 2143b, and the first groove section 2143a and the second groove section 2143b are connected, and the pressure relief component 214 forms a weak section in the area where the first groove section 2143a and the second groove section 2143b are provided. The two weak sections jointly define a predetermined pressure relief area 21431.

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

[0352] A weak section is formed at the bottom of each of the first groove section 2143a and the second groove section 2143b, and the two weak sections together define a predetermined pressure relief area 21431. The first groove section 2143a and the second groove section 2143b are structures arranged along the edge of the predetermined pressure relief area 21431, so that when the battery cell 20 is depressurized, the two weak sections can be split along the edge of the predetermined pressure relief area 21431.

[0353] For example, in Fig. 9 In the embodiment, one end of the first groove section 2143a is connected to one end of the second groove section 2143b, so that the first groove section 2143a and the second groove section 2143b form a first groove 2146 of an "L"-shaped structure. Fig. 9 Of course, in other embodiments, one end of the second slot section 2143b may also be connected to the middle position of the first slot section 2143a, so that the pressure relief component 214 forms a predetermined pressure relief area 21431 on both sides of the second slot section 2143b.

[0354] The first groove section 2143a and the second groove section 2143b are interconnected structures, so that the first groove section 2143a and the second groove section 2143b jointly define a predetermined pressure relief area 21431. On the one hand, the pressure relief area of ​​the battery cell 20 can be increased to increase the pressure relief rate of the battery cell 20. On the other hand, the position where the first groove section 2143a and the second groove section 2143b are interconnected is weaker, which is 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 section 2143a, a second groove section 2143b, and a third groove section 2143c. The first groove section 2143a and the third groove section 2143c are arranged opposite to each other, and the second groove section 2143b connects the first groove section 2143a and the third groove section 2143c. The pressure relief component 214 forms a weak section in the area where the first groove section 2143a, the second groove section 2143b, and the third groove section 2143c are arranged, respectively, and the three weak sections jointly define a predetermined pressure relief area 21431.

[0356] The first slot section 2143a and the third slot section 2143c are arranged at intervals and at least partially opposite to each other. Optionally, the first slot section 2143a and the third slot section 2143c both extend along the first direction.

[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] A weak section is formed at the bottom of each of the first slot section 2143a, the second slot section 2143b and the third slot section 2143c, and the three weak sections together define a predetermined pressure relief area 21431. 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 line, and the first line is arranged opposite to the second slot segment 2143b along the first direction. The closed area enclosed by the weak section corresponding to the first slot segment 2143a, the weak section corresponding to the second slot segment 2143b, the weak section corresponding to the third slot segment 2143c and the first line is the predetermined pressure relief area 21431. That is to say, the first groove section 2143a, the second groove section 2143b and the third groove section 2143c are structures arranged along the edge of the predetermined pressure relief area 21431, so that the predetermined pressure relief area 21431 can be opened with the first groove section 2143a, the second groove section 2143b and the third groove section 2143c as boundaries, that is to say, the predetermined pressure relief area 21431 is formed in the area enclosed by the first groove section 2143a, the second groove section 2143b and the third groove section 2143c, so that the part of the pressure relief component 214 located in the predetermined pressure relief area 21431 can be opened with the first groove section 2143a, the second groove section 2143b and the third groove section 2143c as boundaries when the battery cell 20 is depressurized, thereby releasing the internal pressure of the battery cell 20.

[0359] Reference Fig.10 , Fig.10 Bottom view of the housing 21 of the battery cell 20 provided in some other embodiments of the present application. The shape of the first groove 2146 formed by the first groove section 2143a, the second groove section 2143b and the third groove section 2143c can be a "U" shaped structure, that is, one end of the second groove section 2143b is connected to one end of the first groove section 2143a, and the other end is connected to one end of the third groove section 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 open end of the U-shaped structure.

[0360] The first groove 2146 includes a first groove section 2143a, a second groove section 2143b and a third groove section 2143c. The second groove section 2143b connects the first groove section 2143a and the third groove section 2143c, so that the pressure relief component 214 can be split along the first groove section 2143a, the second groove section 2143b and the third groove section 2143c when the battery cell 20 releases pressure, so as to open the predetermined pressure relief area 21431 to release the internal pressure of the battery cell 20. The first groove 2146 with such a structure makes the connection position between the first groove section 2143a and the second groove section 2143b and the connection position between the first groove section 2143a and the third groove section 2143c weaker, easier to split and open the predetermined pressure relief area 21431 for pressure relief, and can further increase 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 areas 21431, and the two predetermined pressure relief areas 21431 are respectively located on both sides of the second groove section 2143b. At least one second weak portion 2145 is correspondingly disposed in each predetermined pressure relief area 21431.

[0362] See also Figure 5 As shown, the shape of the first groove 2146 formed by the first groove section 2143a, the second groove section 2143b and the third groove section 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 section 2143a.

[0363] Each predetermined pressure relief area 21431 may be provided with one second weak portion 2145, two second weak portions 2145, three second weak portions 2145 or more than three second weak portions 2145, see Figure 5 As shown, each predetermined pressure relief area 21431 is correspondingly provided with a second weak portion 2145 .

[0364] The first weak portion 2144 defines two predetermined pressure relief areas 21431, and each predetermined pressure relief area 21431 is correspondingly provided with at least one second weak portion 2145. When the battery cell 20 is depressurized, the two predetermined pressure relief areas 21431 are flipped open under the guidance of the 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 area 21431 is provided with a corresponding second weak portion 2145 , 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 provided with the second groove 21451 . The 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 grooves 21451 are 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 slot section 2143b.

[0367] See also 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 section 2143a , the second groove section 2143b and the third groove section 2143c are all located between the two second grooves 21451 .

[0368] The predetermined pressure relief area 21431 corresponds to the second weak portion 2145 one by one, which can reduce the number of second weak portions 2145, reduce the number of times the pressure relief component 214 is processed, and reduce the stress of the pressure relief component 214. The first groove 2146 is set between the two second grooves 21451. When the battery cell 20 is depressurized, the pressure relief component 214 can be split along the first groove section 2143a, the second groove section 2143b and the third groove section 2143c, thereby opening the two predetermined pressure relief areas 21431, so that the two predetermined pressure relief areas 21431 are respectively turned over and opened under the guidance of the corresponding second weak portions 2145, so that the battery cell 20 has a larger pressure relief area, which is conducive to improving the pressure relief rate of the battery cell 20 and improving the reliability of the battery cell 20.

[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 deviates from the two ends of the first slot segment 2143a, and the position where the second slot segment 2143b is connected to the third slot segment 2143c deviates from the two ends of the third slot segment 2143c.

[0370] Among them, the connection position of the second groove section 2143b and the first groove section 2143a deviates from the two ends of the first groove section 2143a, that is, the second groove section 2143b is connected between the two ends of the first groove section 2143a. Similarly, the connection position of the third groove section 2143c and the second groove section 2143b deviates from the two ends of the third groove section 2143c, that is, the second groove section 2143b is connected between the two ends of the third groove section 2143c, so that the shape of the first groove 2146 formed by the first groove section 2143a, the second groove section 2143b and the third groove section 2143c is a structure approximately in an "H" shape.

[0371] By setting the connection position of the second groove section 2143b and the first groove section 2143a to be located between the two ends of the second groove section 2143b, and setting the connection position of the second groove section 2143b and the third groove section 2143c to be located between the two ends of the third groove section 2143c, so that the first groove section 2143a, the second groove section 2143b and the third groove section 2143c form a structure similar to an "H" shape, so that both sides of the second groove section 2143b of the first groove 2146 can form a predetermined pressure relief area 21431, and the two predetermined pressure relief areas 21431 can be opened in a split manner for pressure relief when the battery cell 20 is relieved of pressure, which is beneficial to further increase the pressure relief effect of the battery cell 20 and can effectively improve the pressure relief rate of the battery cell 20.

[0372] In some embodiments, see Figure 5 As shown, the first slot section 2143a, the second slot section 2143b and the third slot section 2143c all extend along a straight track, and the first slot section 2143a and the third slot section 2143c are both perpendicular to the second slot section 2143b. In other words, the extension direction of the second slot section 2143b is perpendicular to the extension direction of the first slot section 2143a and the extension direction of the third slot section 2143c, so that the shape of the first groove 2146 formed by the first slot section 2143a, the second slot section 2143b and the third slot section 2143c is an "H"-shaped structure, and two predetermined pressure relief areas 21431 are formed on both sides of the second slot section 2143b. Of course, the areas of the two predetermined pressure relief areas 21431 can be the same or different.

[0373] By setting the first groove section 2143a and the third groove section 2143c to be perpendicular to the second groove section 2143b, so that the extension direction of the second groove section 2143b is the arrangement direction of the first groove section 2143a and the third groove section 2143c, on the one hand, the regularity of the shape of the first groove 2146 can be improved, which is conducive to reducing the processing difficulty of the first groove 2146, so as to reduce the manufacturing cost of the battery cell 20; on the other hand, it is convenient for the two predetermined pressure relief areas 21431 on the pressure relief component 214 located on both sides of the second groove section 2143b to relieve pressure in opposite directions when the battery cell 20 is relieved of pressure.

[0374] According to some embodiments of the present application, referring to Fig.11 , Fig.11 The bottom view of the housing 21 of the battery cell 20 provided in some embodiments of the present application. The first groove section 2143a, the second groove section 2143b and the third groove section 2143c all extend along an arc trajectory.

[0375] For example, in Fig.11In the embodiment, two ends of the second slot segment 2143b are respectively connected to one end of the first slot segment 2143a and one end of the third slot segment 2143c, and the first slot segment 2143a, the second slot segment 2143b and the third slot segment 2143c all extend along an arc track, so that the first slot segment 2143a, the second slot segment 2143b and the third slot segment 2143c form a first groove 2146 similar to 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 section 2143a, the second groove section 2143b and the third groove section 2143c to be structures extending along an arc trajectory, it is beneficial to improve the arc degree of the connection position of the first groove section 2143a and the second groove section 2143b, and the arc degree of the connection position of the second groove section 2143b and the third groove section 2143c. On the one hand, it can reduce the difficulty of processing the first groove 2146, and on the other hand, it can facilitate the pressure relief component 214 to open the predetermined pressure relief area 21431 after splitting along the first groove section 2143a, the second groove section 2143b and the third groove section 2143c to release the internal pressure of the battery cell 20.

[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 provided with the second groove 21451. The first groove section 2143a, the second groove section 2143b and the third groove section 2143c are all spaced apart from the second groove 21451.

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

[0379] By arranging the first groove section 2143a, the second groove section 2143b and the third groove section 2143c to be spaced apart from the second groove 21451, on the one hand, the mutual influence between the first groove 2146 and the second groove 21451 during the processing can be reduced; on the other hand, the phenomenon that the pressure relief component 214 cracks along the second groove 21451 when the pressure relief component 214 cracks along the first groove 2146 to relieve pressure can be reduced, and the stress influence between the area where the first groove 2146 of the pressure relief component 214 is set and the area where the second groove 21451 of the pressure relief component 214 is set can be reduced.

[0380] In some embodiments, the second slot segment 2143 b and the second groove 21451 are arranged opposite to each other along the first direction. Along the first direction, the first slot segment 2143 a and the third slot segment 2143 c are arranged spaced apart from the second groove 21451 .

[0381] Along the first direction, the second slot section 2143b is arranged opposite to the second groove 21451, and the first slot section 2143a and the third slot section 2143c are arranged at intervals from the second groove 21451. There is a distance between the first slot section 2143a and the second groove 21451 in the direction in which the second slot section 2143b and the second groove 21451 are arranged opposite to each other. There is a distance between the third slot section 2143c and the second groove 21451 in the direction in which the second slot section 2143b and the second groove 21451 are arranged opposite to each other.

[0382] By arranging the second groove section 2143b and the second groove 21451 relative to each other along the first direction, the first groove section 2143a and the third groove section 2143c are spaced apart from the second groove 21451 in the first direction, so that the predetermined pressure relief area 21431 defined by the first groove section 2143a, the second groove section 2143b and the third groove section 2143c can be flipped around the area of ​​the pressure relief component 214 where the second groove 21451 is provided when being opened, and the flipping angle of the predetermined pressure relief area 21431 after being opened can be increased, so as to increase the pressure relief area of ​​the battery cell 20.

[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 housing 21, and the third outer surface 2113 is rectangular. The first direction is parallel to the length direction or the width direction of the rectangle.

[0384] The second groove section 2143b and the second groove 21451 are arranged along the length direction or width direction of the third outer surface 2113, and along the length direction or width direction of the third outer surface 2113, the first groove section 2143a and the third groove section 2143c are spaced from the second groove 21451. The space in the length direction or width direction of the third outer surface 2113 is large, and it is easy to process the first groove 2146 and the second groove 21451. In addition, during production, the detonation pressure of the processed multiple battery cells 20 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 arranged opposite to each other in the thickness direction of the first wall 211, and the pressure relief component 214 is provided with a first groove 2146, and the first groove 2146 is a multi-level groove arranged in sequence from the first surface 2111 to the second surface 2112. In two adjacent levels of grooves, the first level groove far from the first surface 2111 is arranged at the groove bottom surface of the first level groove close to the first surface 2111. Among the multi-level grooves, the groove bottom wall of the first level groove farthest from the first surface 2111 is the first weak portion 2144.

[0386] The pressure relief component 214 is provided with multiple grooves, which are sequentially arranged on the pressure relief component 214 from the first surface 2111 to the second surface 2112, and the contour of the bottom surface of the multiple grooves decreases step by step. The cross-sectional shape of the groove can be various, such as rectangular, circular, etc. The groove on the pressure relief component 214 can be processed and formed in various ways, such as stamping, cold heading, etc.

[0387] The bottom wall of the first-stage groove farthest from the first surface 2111 among the multi-stage grooves is the first weak portion 2144 , that is, the portion of the pressure relief component 214 located between the bottom surface of the first groove 2146 farthest from the first surface 2111 and the second surface 2112 is the first weak portion 2144 .

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

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

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

[0391] The multi-level grooves are sequentially arranged on the pressure relief component 214 along the direction from the first surface 2111 to the second surface 2112. During molding, the multi-level grooves can be molded step by step, thereby reducing the molding force on the pressure relief component 214 and reducing the risk of cracks in the pressure relief component 214. The pressure relief component 214 is not likely to fail due to cracks at the position where the grooves are arranged, thereby improving the reliability of the battery cell 20. When molding the multi-level grooves, stamping or cold heading can be used, so that the groove wall of the groove will undergo cold work hardening (the grain arrangement changes, resulting in lattice distortion, reducing the plasticity of the metal and increasing the hardness of the material), and its ability to resist external impact is enhanced, and it is not easily damaged by external impact. In this way, it is helpful to reduce the risk of leakage of 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 notch of the first groove 2146 and the groove 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 be any point value among 0.16, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 0.99, etc., or a range of values ​​between any two of them.

[0395] It is understandable that if the pressure relief component 214 and the first wall 211 are integrally formed, the first wall 211 can serve as the pressure relief component 214 , and the thickness of the pressure relief component 214 is the thickness of the first wall 211 .

[0396] In this embodiment, 0.16≤F / N<1, so that the maximum depth of the first groove 2146 accounts for a small proportion of the thickness of the pressure relief component 214, and the bursting pressure of the battery cell 20 is not too high, which is beneficial to improving the timeliness of the pressure relief of the battery cell 20.

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

[0398] F can be any point value among 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.55 mm, 1.6 mm, 1.65 mm, 1.7 mm, 1.75 mm, 1.8 mm, 1.85 mm, 1.9 mm, 1.95 mm, 2 mm, etc., or any range value between any two of them.

[0399] N can be any point value among 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.55 mm, 1.6 mm, 1.65 mm, 1.7 mm, 1.75 mm, 1.8 mm, 1.85 mm, 1.9 mm, 1.95 mm, 2 mm, 2.05 mm, 2.1 mm, 2.15 mm, 2.2 mm, 2.25 mm, 2.3 mm, 2.35 mm, 2.4 mm, 2.45 mm, 2.5 mm, etc., or a range value between any two of them.

[0400] In this embodiment, 0.4 mm ≤ F ≤ 2 mm, 0.8 mm ≤ N ≤ 2.5 mm, so that the maximum depth of the first groove 2146 and the thickness of the pressure relief component 214 are within a reasonable range, which has better economy. In the embodiment where the first wall 211 is used as the pressure relief component 214, the thickness of the first wall 211 is 0.8 mm to 2.5 mm, and the thickness of the first wall 211 is greater than or equal to 0.8 mm, so that the first wall 211 has sufficient strength, and the thickness of the first wall 211 is less than or equal to 2 mm, so that the thickness of the first wall 211 is not too thick. When the volume of the shell 21 is constant, the internal space of the shell 21 can be increased to make more space for the electrode assembly 22. When the thickness of the first wall 211 is controlled within the range of 0.8 mm to 2.5 mm, the maximum groove depth of the first groove 2146 is controlled within the range of 0.4 mm to 2 mm, so that the maximum groove depth of the first groove 2146 is more matched with the thickness of the pressure relief component 214, so that the pressure relief component 214 has good pressure relief capacity.

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

[0402] Integrally formed means that the first wall 211 and the pressure relief component 214 are an integral structure when provided. For example, the pressure relief component 214 can be formed on the first wall 211 by stamping or cold heading.

[0403] The pressure relief component 214 and the first wall 211 are integrally formed without additional welding or bonding processes, which is conducive to reducing the risk of leakage of the pressure relief component 214. In addition, during production, it is easy to make the detonation pressure of the processed multiple battery cells 20 more consistent.

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

[0405] Exemplarily, the material of the first wall 211 may be carbon steel, alloy steel, stainless steel, or the like.

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

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

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

[0409] Illustratively, the carbon steel may 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 of the first wall 211 , which has low cost and is easy to manufacture.

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

[0412] It is understandable that in the embodiment where the pressure relief component 214 and the first wall 211 are integrally formed, the material of the first wall 211 includes aluminum alloy. If the first wall 211 is an end cover 216, the end cover 216 can be made of aluminum alloy; if the first wall 211 is a wall portion in the housing 215, the housing 215 can be made of aluminum alloy.

[0413] Aluminum alloy has the characteristics of light weight and good ductility, and it is easier to process the first groove 2146 and the second groove 21451 on the pressure relief component 214. In the embodiment where the pressure relief component 214 and the first wall 211 are integrally formed, the first wall 211 is made of aluminum alloy, which can effectively reduce the difficulty of forming the first wall 211.

[0414] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other single elements ≤ 0.03%.

[0415] This aluminum alloy belongs to the third series aluminum, and has lower hardness and better forming ability, which reduces the difficulty of processing the first groove 2146 and the second groove 21451, is beneficial to improving the processing accuracy of the first groove 2146 and the second groove 21451, and improves the pressure relief consistency of the pressure relief component 214.

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

[0417] This aluminum alloy belongs to the fifth series aluminum. The pressure relief component 214 made of this aluminum alloy has higher hardness, greater strength and good anti-destruction ability.

[0418] In other embodiments, the pressure relief component 214 is separately provided 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 pressure relief component 214 is separately provided 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” means that during manufacturing, a pressure relief hole is opened on the first wall 211, and the pressure relief component 214 and the first wall 211 are provided separately and finally connected together. For example, the pressure relief component 214 can be welded to the first wall 211. The pressure relief component 214 can be a burst-proof disk installed on the first wall 211.

[0420] The pressure relief component 214 is provided separately 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, and the electrode assembly 22 is accommodated in the housing 21. The first wall 211 supports the electrode assembly 22 along the gravity direction.

[0422] The first wall 211 is a wall on the housing 21 that supports the electrode assembly 22 along the gravity direction. It can be understood that the first wall 211 can be the bottom wall of the housing 215. The first wall 211 can also be an end cover 216. When the first wall 211 is the end cover 216, the battery cell 20 is used upside down.

[0423] The first wall 211 supports the electrode assembly 22 along the direction of gravity, and the pressure relief component 214 is arranged on the first wall 211. In this way, when the battery cell 20 is depressurized, the ejected fluid medium is not easy to act on other electrical connection components, reducing the risk of short circuit when the battery cell 20 is depressurized.

[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 , and the electrode terminal 23 is disposed on other walls of the housing 21 except 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 of the housing 215 or the end cover 216. For another example, when the first wall 211 is one side wall of the housing 215, the electrode terminal 23 can be disposed on other side walls, the bottom wall or the end cover 216 of the housing 215. When the first wall 211 is the end cover 216, the electrode terminal 23 can be disposed on the side wall or the bottom wall of the housing 215.

[0426] The electrode terminal 23 and the pressure relief component 214 are respectively arranged on different walls of the shell 21. When the battery cell 20 is depressurized, the ejected fluid medium is not easy to act on the electrode terminal 23 and cause the electrode terminal 23 to short-circuit, thereby reducing the risk of short circuit when the battery cell 20 is depressurized.

[0427] Optionally, the electrode terminal 23 is disposed on a wall of the 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 may be disposed on the end cap 216. When the first wall 211 is one side wall of the housing 215, the electrode terminal 23 may be disposed on the other 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 may be disposed on the bottom wall of the housing 215.

[0429] The electrode terminal 23 is arranged on the wall of the shell 21 opposite to the first wall 211. The electrode terminal 23 is far away from the pressure relief component 214. When the battery cell 20 is depressurized, the ejected fluid medium is less likely to act on the electrode terminal 23 and cause the electrode terminal 23 to short-circuit, further reducing the risk of short circuit when the battery cell 20 is depressurized.

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

[0431] The shell 215 includes an integrally formed side wall and a bottom wall, that is, the shell 215 is manufactured by an integral molding process, such as an integral molding process such as stamping, casting or extrusion molding, that is, the side wall and the bottom wall of the shell 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. Figure 5 and Figure 6 In the embodiment, the first wall 211 is a bottom wall of the housing 215 disposed opposite to the end cover 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 may also be other structures. For example, the outer shell 21 may include a shell 215 and an end cover 216. The interior of the shell 215 forms a accommodating cavity with an opening 2151, and the accommodating cavity is used to accommodate the electrode assembly 22. The end cover 216 closes the opening 2151, and the end cover 216 is the first wall 211.

[0434] It should be noted that the structure of the battery cell 20 can be various. In some embodiments, the outer shell 21 may include a shell 215 and two end covers 216. The shell 215 has a housing cavity formed inside, which is used to accommodate the electrode assembly 22. The shell 215 has openings 2151 formed at both ends of the first wall 211 in the thickness direction, and the two openings 2151 are connected to the housing cavity. The two end covers 216 respectively close the two openings 2151, and one of the two end covers 216 is the first wall 211.

[0435] The shell 215 of the outer shell 21 is provided with openings 2151 at both ends in the thickness direction of the first wall 211, and the two end covers 216 respectively close the two openings 2151. The first wall 211 is one of the two end covers 216. The battery cell 20 adopting this structure is convenient for assembling the battery cell 20 from both ends of the shell 215, which is beneficial to reducing the manufacturing difficulty and assembly difficulty of the battery cell 20.

[0436] When the end cover 216 is the first wall 211, the pressure relief component 214 is disposed on the end cover 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 a wall of the housing 215, and the fluid medium ejected by the pressure relief component 214 is not likely to act on other electrical connection structures on the end cover 216, which is conducive to reducing the risk of short circuit of the battery cell 20.

[0437] The embodiment of the present application further provides a battery 100 , and the battery 100 includes the above-mentioned battery cell 20 .

[0438] The embodiment of the present application further provides an electrical device, which includes the above-mentioned battery cell 20.

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

[0440] The embodiment of the present application provides a battery cell 20, which includes a housing 21 and a pressure relief component 214, wherein 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, and the pressure relief component 214 is configured to be able to split along at least a portion of the first weak portion 2144 when the battery cell 20 is depressurized. The pressure relief component 214 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 to open at least a portion of the predetermined pressure relief area 21431. The battery cell 20 is provided with a first weak portion 2144 and a second weak portion 2145, and when the battery cell 20 is depressurized, the first weak portion 2144 splits to allow the fluid medium in 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, thereby achieving rapid pressure relief, reducing the risk of explosion and fire of the battery cell 20, and is beneficial to improving the reliability of the 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 portion 2144 and the first outer surface 2121 is L1, and the minimum distance between the first weak portion 2144 and the second outer surface 2131 is L2, which satisfies: 0≤|L1-L2| / L≤0.1. When 0≤|L1-L2| / L≤0.1, the position of the first weak portion 2144 is close to the middle position of the first wall 211 along the first direction, and the rigidity of the middle position of the first wall 211 along the first direction is relatively small. When the battery cell 20 is depressurized, the middle position of the first wall 211 along the first direction will be greatly deformed, which is conducive to the first weak portion 2144 being cracked before the second weak portion 2145, so that the predetermined pressure relief area 21431 can be flipped open under the guidance of the second weak portion 2145, which is conducive to improving the reliability of the battery cell 20.

[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, and a cross-sectional area of ​​the weak segment perpendicular to its extension direction is S1, and a 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 from the middle position of the first wall 211 along the first direction by a large distance. At this time, the second weak portion 2145 is close to the first outer surface 2121. The stiffness of the first wall 211 at the second weak portion 2145 is greatly different from the stiffness of the first wall 211 at 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. If the impact of the stiffness on the first weak portion 2144 and the second weak portion 2145 is not considered, the cross-sectional area of ​​the second weak portion 2145 perpendicular to its extension direction only needs to be greater than the cross-sectional area of ​​the weak section perpendicular to its extension direction, that is, S2 / S1>1, so that the first weak portion 2144 opens to release pressure before the second weak portion 2145, and the second weak portion 2145 plays a guiding role in the predetermined pressure relief area 21431. However, considering that the rigidity has a greater impact on the splitting of the first weak portion 2144 and the second weak portion 2145 (under the same cross-sectional area, the second weak portion 2145 is more difficult to split than the first weak portion 2144, so the cross-sectional area of ​​the second weak portion 2145 can be set smaller), when 0.7<S2 / S1≤1, the first weak portion 2144 can also be opened to release pressure before the second weak portion 2145, and the second weak portion 2145 plays a guiding role in the predetermined pressure relief area 21431. Similarly, since the rigidity has a greater impact on the splitting of the first weak portion 2144 and the second weak portion 2145, when S2 / S1≤1.5, the strength of the pressure relief component 214 at the position of the second weak portion 2145 is smaller, and the obstacle to the flipping and opening of the predetermined pressure relief area 21431 is smaller, making it easier for the predetermined pressure relief area 21431 to flip and open under the action of the fluid medium.

[0443] Along the first direction, a second weak portion 2145 is arranged between the first weak portion 2144 and the first outer surface 2121; along the first direction, the distance between the first outer surface 2121 and the second outer surface 2131 is L, the minimum distance between the second weak portion 2145 and the first outer surface 2121 is L3, and the minimum distance between the second weak portion 2145 and the second outer surface 2131 is L4. The first weak portion 2144 includes at least one weak segment, and the cross-sectional area of ​​the weak segment perpendicular to its extension direction is S1, 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 of the second weak portion 2145 from the middle 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 middle 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 slightly different from the stiffness of the first wall 211 at the position of the first weak portion 2144. The stiffness has little effect 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 be opened to release pressure before the second weak portion 2145. The second weak portion 2145 plays a guiding role in the predetermined pressure relief area 21431, reducing the risk of the second weak portion 2145 cracking before the first weak portion 2144. When S2 / S1≤5, the strength of the pressure relief component 214 at the second weak portion 2145 is relatively small, and the obstacle to the predetermined pressure relief area 21431 flipping open is relatively small, making it easier for the predetermined pressure relief area 21431 to flip open under the action of the fluid medium.

[0444] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, It is characterized in that include: A housing having a first wall, the first wall including a first weak portion, the first weak portion defining a predetermined pressure relief area, the first wall being configured to be split along at least a portion of the first weak portion when the battery cell is depressurized; Wherein, the first wall further includes a second weak portion, and the second weak portion is configured to guide at least a portion of the predetermined pressure relief area to flip over so as to open at least a portion of the predetermined pressure relief area.

2. The battery cell according to claim 1, It is characterized in that The housing comprises a second wall and a third wall arranged opposite to each other along a first direction, the first wall connects the second wall and the third wall, 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, the second weak portion is arranged between the first weak portion and the first outer surface and / or between the first weak portion and the second outer surface.

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

4. The battery cell according to claim 3, It is characterized in that The first width is a 1 , meet: 0.01mm≤a 1 ≤0.8mm, optionally, 0.05mm≤a 1 ≤0.5mm, optionally, 0.1mm≤a 1 ≤0.3mm; and / or The first thickness is h 1 , meet: 0.02mm≤h 1 ≤1mm, optionally, 0.04mm≤h 1 ≤0.6mm, optionally, 0.08mm≤h 1 ≤0.4mm; and / or The second width is a 2 , meet: 0.01mm≤a 2 ≤0.5mm, optionally, 0.04mm≤a 2 ≤0.3mm, optionally, 0.06mm≤a 2 ≤0.15mm; and / or The second thickness is h 2 , meet: 0.1mm≤h 2 ≤2mm, optionally, 0.2mm≤h 2 ≤1.5mm, optionally, 0.5mm≤h 2 ≤1mm.

5. The battery cell according to claim 3, It is characterized in that Along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the first weak portion and the first outer surface is a second distance, the minimum distance between the first weak portion and the second outer surface is a third distance, and the ratio of the difference between the second distance and the third distance to the first distance is greater than or equal to 0 and less than or equal to 0.

1.

6. The battery cell according to claim 5, It is characterized in that The first wall has a third outer surface facing away from the interior of the housing, and along the thickness direction of the first wall, the projection of the first weak portion covers the center of the third outer surface.

7. The battery cell according to claim 3, It is characterized in that Along the first direction, the second weak portion is provided between the first weak portion and the first outer surface; Along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the second weak portion and the first outer surface is a fourth distance, and the minimum distance between the second weak portion and the second outer surface is a fifth distance. The first weak portion includes at least one weak segment, and the cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area. The cross-sectional area of ​​the second weak portion perpendicular to its extension direction is a second cross-sectional area. When the ratio of the difference between the fifth distance and the fourth distance to the first distance is greater than or equal to 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 0.7 and less than or equal to 1.

5.

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

9. The battery cell according to claim 7, It is 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.

10. The battery cell according to claim 3, It is characterized in that Along the first direction, the second weak portion is provided between the first weak portion and the first outer surface; Along the first direction, the distance between the first outer surface and the second outer surface is a first distance, the minimum distance between the second weak portion and the first outer surface is a fourth distance, and the minimum distance between the second weak portion and the second outer surface is a fifth distance. The first weak portion includes at least one weak segment, and the cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area. The cross-sectional area of ​​the second weak portion perpendicular to its extension direction is a second cross-sectional area. When the ratio of the difference between the fifth distance and the fourth distance to the first distance is less than 0.4, the ratio of the second cross-sectional area to the first cross-sectional area is greater than 1.5 and less than or equal to 5.

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

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

67.

13. The battery cell according to claim 10, It is 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.

14. The battery cell according to claim 7, It is characterized in that The first cross-sectional area is S 1 , meet: 0.0002mm 2 ≤S 1 ≤0.8mm 2 , optionally, 0.002mm 2 ≤S 1 ≤0.3mm 2 , optionally, 0.008mm 2 ≤S 1 ≤0.12mm 2 .

15. The battery cell according to claim 7, It is characterized in that The second cross-sectional area is S 2 , meet: 0.001mm 2 ≤S 2 ≤1mm 2 , optionally, 0.008mm 2 ≤S 2 ≤0.45mm 2 ; Optionally, 0.03mm 2 ≤S 2 ≤0.15mm 2 .

16. The battery cell according to any one of claims 1 to 15, It is characterized in that The first wall is provided with a second groove, the first wall forms the second weak portion in a region where the second groove is provided, and the second groove is provided on a surface of the first wall facing the interior of the housing.

17. The battery cell according to any one of claims 1 to 15, It is characterized in that The first wall has a first surface and a second surface arranged opposite to each other in the thickness direction of the first wall, the first surface is provided with a first groove, and the first wall forms the first weak portion in the area where the first groove is provided, the second surface is provided with a second groove, and the first wall forms the second weak portion in the area where the second groove is provided.

18. The battery cell according to claim 17, It is characterized in that The first surface is a surface of the first wall facing away from the interior of the housing, and the second surface is a surface of the first wall facing the interior of the housing.

19. The battery cell according to any one of claims 1 to 15, It is characterized in that The first wall is provided with a first groove, and the first wall forms the first weak portion in the area where the first groove is provided, the first groove includes a first groove section and a second groove section, the first groove section and the second groove section are connected, and the first wall forms a weak section in the area where the first groove section and the second groove section are provided, respectively, and the two weak sections jointly define the predetermined pressure relief area.

20. The battery cell according to any one of claims 1 to 15, It is characterized in that The first wall is provided with a first groove, and the first wall forms the first weak portion in the area where the first groove is provided, the first groove includes a first groove section, a second groove section and a third groove section, the first groove section and the third groove section are arranged opposite to each other, the second groove section connects the first groove section and the third groove section, and the first wall forms a weak section in the area where the first groove section, the second groove section and the third groove section are provided, respectively, and the three weak sections jointly define the predetermined pressure relief area.

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

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

23. The battery cell according to claim 20, It is characterized in that The position where the second slot segment is connected to the first slot segment deviates from the two ends of the first slot segment, and the position where the second slot segment is connected to the third slot segment deviates from the two ends of the third slot segment.

24. The battery cell according to claim 20, It is characterized in that The first wall is provided with a second groove, the first wall forms the second weak portion in a region where the second groove is provided, and the first groove section, the second groove section and the third groove section are all spaced apart from the second groove.

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

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

27. The battery cell according to any one of claims 1 to 15, It is characterized in that The first wall has a first surface and a second surface arranged opposite to each other in the thickness direction of the first wall, the first wall is provided with a first groove, the first groove comprises a plurality of grooves arranged in sequence from the first surface to the second surface, and in two adjacent grooves, a first groove away from the first surface is arranged at a groove bottom surface of the first groove close to the first surface; Among the multi-stage grooves, the bottom wall of the first-stage groove farthest from the first surface is the first weak portion.

28. The battery cell according to any one of claims 1 to 15, It is characterized in that The battery cell includes an electrode assembly, the electrode assembly is accommodated in the housing, and the first wall supports the electrode assembly along a gravity direction.

29. The battery cell according to any one of claims 1 to 15, It is characterized in that The battery cell includes an electrode terminal, and the electrode terminal is disposed on a wall of the housing other than the first wall.

30. The battery cell according to claim 29, It is characterized in that The electrode terminal is disposed on a wall of the housing opposite to the first wall.

31. The battery cell according to any one of claims 1 to 15, It is characterized in that The housing comprises: a housing having an opening; an end cover connected to the housing and closing the opening; Wherein, the end cover is the first wall, or the shell includes the first wall.

32. A battery, It is characterized in that Comprising a battery cell according to any one of claims 1-31.

33. An electrical device, It is characterized in that Comprising a battery cell according to any one of claims 1-31.

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