Battery cell, battery device and electric device

Abstract

The present application belongs to the technical field of batteries. Provided are a battery cell, a battery device and an electric device. The battery cell comprises a casing, an electrode assembly, and a pressure relief mechanism, wherein the casing has a wall portion, and the electrode assembly is accommodated in the casing. The pressure relief mechanism is arranged on the wall portion, and the pressure relief mechanism comprises a weak portion and a connection portion, wherein the weak portion is annular, a region enclosed by the weak portion is a pressure relief region, and the connection portion comprises a first portion and a second portion, the first portion being connected to the wall portion, and the second portion connecting the weak portion and the first portion. The second portion is bent to form a plurality of bent sections that are connected in sequence, the bent sections surround the outer side of the weak portion, and the bent sections at two ends among the plurality of bent sections are respectively connected to the first portion and the weak portion. By means of the second portion, a buffering effect can be achieved between the first portion and the weak portion, thereby helping reduce the effect of a stress generated on the casing on the weak portion, and then reducing the risks of fatigue cracking, etc., of the weak portion during usage.

Description

Battery cells, battery packs and electrical devices Technical Field

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

[0002] In recent years, new energy vehicles have experienced rapid development. In the field of electric vehicles, power batteries, as the power source, play an irreplaceable and crucial role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also increasing. Among them, battery devices, as core components of new energy vehicles, have high requirements in terms of reliability and service life.

[0003] In battery technology, to ensure the safety of individual battery cells, a pressure relief mechanism is typically installed on the casing of each cell to release internal pressure. This mechanism is activated when the internal pressure or temperature reaches a threshold, releasing the pressure within the cell. However, existing pressure relief mechanisms often prematurely open during use, resulting in poor stability and hindering the improvement of cell lifespan and reliability. Summary of the Invention

[0004] This application provides a battery cell, a battery device, and an electrical device, which can effectively improve the service life and reliability of the battery cell.

[0005] In a first aspect, embodiments of this application provide a battery cell, including a casing, an electrode assembly, and a pressure relief mechanism; the casing has a wall portion; the electrode assembly is housed within the casing; the pressure relief mechanism is disposed on the wall portion, the pressure relief mechanism includes a weak portion and a connecting portion, the weak portion is configured to be at least partially destroyed to release the pressure when the pressure inside the casing reaches a threshold, the weak portion is annular, and the area enclosed by the weak portion is a pressure relief zone, the connecting portion includes a first portion and a second portion, the first portion is connected to the wall portion, and the second portion is connected to the weak portion and the first portion; wherein, the second portion is bent to form a plurality of sequentially connected bent segments, the bent segments surround the outside of the weak portion, and the bent segments at both ends of the plurality of bent segments are respectively connected to the first portion and the weak portion.

[0006] In the above technical solution, a pressure relief mechanism is provided on the wall of the outer casing. The pressure relief mechanism has a weak part, which is configured to be at least partially destroyed when the pressure inside the outer casing reaches a threshold to release the pressure, thereby releasing the internal pressure of the battery cell and reducing the risk of the battery cell bursting or exploding during use. Specifically, the connecting part is configured as a first part and a second part that are interconnected. The first part is connected to the wall, and the second part is configured as a structure with multiple sequentially connected bent segments, where the bent segments surround the weak part. This ensures that the bent segments at both ends of the multiple bent segments connect the first part and the weak part respectively. This design connects the weak part to the first part via a second part. The second part acts as a buffer between the first and weak parts, mitigating the stress transmitted from the outer casing to the weak part during impact or expansion. This enhances the fatigue resistance of the pressure relief mechanism, effectively reducing strain and strain amplitude in the weak part during use. This lowers the risk of fatigue cracking in the weak part of the pressure relief mechanism, thus mitigating premature valve opening and pressure release. Ultimately, this improves the reliability and lifespan of the battery cell.

[0007] In some embodiments, the first portion has opposing first and second surfaces in the thickness direction of the wall portion, and the second portion protrudes from the second surface along the direction from the first surface to the second surface; wherein the pressure relief mechanism is provided with a groove, the groove being recessed from the first surface along the direction from the first surface to the second surface, and the second portion, the weak portion, and the pressure relief area together enclose at least a portion of the groove.

[0008] In the above technical solution, the pressure relief mechanism has a groove on one side of the wall thickness direction. By setting the second part as a structure that protrudes from the second surface of the first part in the direction of the wall thickness direction from the first surface to the second surface, and the second part, the weak part and the pressure relief area together enclose at least part of the groove of the pressure relief mechanism, the battery cell with this structure can reduce the difficulty of bending the second part into multiple bent segments connected in sequence, and can reduce the difficulty of forming the second part between the first part and the weak part. On the other hand, it can optimize the spatial layout of the second part in the wall thickness direction, which is conducive to alleviating the phenomenon that the second part occupies the space on both sides of the first part.

[0009] In some embodiments, within the cross-section of the connection, the angle between the surfaces of two adjacent bent segments facing the groove is α, satisfying 90°≤α≤150°.

[0010] In the above technical solution, the angle between the surfaces of two adjacent bending segments facing the groove is 90 degrees to 150 degrees. On the one hand, setting the angle between the surfaces of two adjacent bending segments facing the groove to be greater than or equal to 90 degrees can reduce the forming difficulty of the second part bending into multiple bending segments connected in sequence, and can alleviate the phenomenon of large stress concentration at the connection position of two adjacent bending segments. On the other hand, setting the angle between the surfaces of two adjacent bending segments facing the groove to be less than or equal to 150 degrees can improve the buffering effect between the second part and the first part, which is beneficial to reduce the stress transmitted to the weak part through the connection when the shell is subjected to impact or expansion, thereby improving the fatigue resistance of the pressure relief mechanism and reducing the risk of fatigue cracking in the weak part of the pressure relief mechanism during use.

[0011] In some embodiments, 100°≤α≤140°.

[0012] In the above technical solution, the angle between the surfaces of two adjacent bending segments facing the groove is 100 to 140 degrees. On the one hand, setting the angle between the surfaces of two adjacent bending segments facing the groove to be greater than or equal to 100 degrees can further reduce the forming difficulty of the second part bending into a series of connected bending segments, and can further alleviate the phenomenon of large stress concentration at the connection position of two adjacent bending segments. On the other hand, setting the angle between the surfaces of two adjacent bending segments facing the groove to be less than or equal to 140 degrees can further improve the buffering effect of the second part between the weak part and the first part, which is conducive to further reducing the stress transmitted to the weak part through the connection when the shell is subjected to impact or expansion, thereby further improving the fatigue resistance of the pressure relief mechanism, and thus further reducing the risk of fatigue cracking in the weak part of the pressure relief mechanism during use.

[0013] In some embodiments, the plurality of bending segments include a first bending segment connected to the first portion, wherein within the cross-section of the connection portion, the angle between the surface of the first bending segment facing away from the groove and the second surface is β, satisfying 80°≤β≤150°.

[0014] In the above technical solution, the angle between the surface of the first bending segment away from the groove and the second surface of the first part is 80 degrees to 150 degrees. On the one hand, setting the angle between the surface of the first bending segment away from the groove and the second surface of the first part to be greater than or equal to 80 degrees can reduce the connection difficulty between the first part and the first bending segment, thereby reducing the forming difficulty of the connection part, and can alleviate the phenomenon of large stress concentration at the connection position of the first part and the first bending segment. On the other hand, setting the angle between the surface of the first bending segment away from the groove and the second surface of the first part to be less than or equal to 150 degrees can alleviate the phenomenon of the first bending segment having an excessively large bending angle compared to the first part, thereby reducing the space occupied by the connection part in the thickness direction of the wall, which is beneficial to optimizing the space utilization rate of the battery cell, and can improve the buffering effect between the second part and the first part, which is beneficial to reducing the stress transmitted to the weak part through the connection part when the shell is subjected to impact or expansion.

[0015] In some embodiments, 85°≤β≤100°.

[0016] In the above technical solution, the angle between the surface of the first bending segment away from the groove and the second surface of the first part is 85 degrees to 100 degrees. On the one hand, setting the angle between the surface of the first bending segment away from the groove and the second surface of the first part to be greater than or equal to 85 degrees can further reduce the connection difficulty between the first part and the first bending segment, thereby further reducing the forming difficulty of the connection part, and can further alleviate the phenomenon of large stress concentration at the connection position of the first part and the first bending segment. On the other hand, setting the angle between the surface of the first bending segment away from the groove and the second surface of the first part to be less than or equal to 100 degrees can further alleviate the phenomenon of the first bending segment having an excessively large bending angle compared to the first part, thereby further reducing the space occupied by the connection part in the thickness direction of the wall, which is beneficial to optimizing the space utilization rate of the battery cell, and can further improve the buffering effect between the second part and the weak part and the first part, which is beneficial to further reduce the stress transmitted to the weak part through the connection part when the shell is subjected to impact or expansion.

[0017] In some embodiments, along the thickness direction of the wall portion, the second portion protrudes from the second surface by a dimension L1, satisfying 0.2mm≤L1≤7mm.

[0018] In the above technical solution, the second part protrudes from the second surface in the thickness direction of the wall by 0.2mm to 7mm. On the one hand, setting the size of the second part protruding from the second surface to be greater than or equal to 0.2mm can reduce the difficulty of bending the second part between the first part and the weak part to form multiple bending segments, thereby reducing the molding difficulty of the second part and improving the buffering effect between the weak part and the first part. On the other hand, setting the size of the second part protruding from the second surface to be less than or equal to 7mm can reduce the space occupied by the connecting part in the thickness direction of the wall, which is beneficial to optimizing the space utilization of the battery cell.

[0019] In some embodiments, 0.2mm ≤ L1 ≤ 5mm.

[0020] In the above technical solution, by further setting the size of the second part protruding from the second surface to less than or equal to 5mm, the space occupied by the connecting part in the thickness direction of the wall can be further reduced, which is conducive to further improving the space utilization rate of the battery cell.

[0021] In some embodiments, the second surface is disposed facing the electrode assembly along the thickness direction of the wall portion.

[0022] In the above technical solution, by setting the second surface of the first part to face the electrode assembly, the second part of the connecting part protrudes from the first part and faces the inside of the battery cell. This results in the groove formed by the second part, the weak part, and the pressure relief area being recessed into the inside of the battery cell. The battery cell with this structure can provide a certain degree of protection for the second part and the weak part connecting the second part, which helps to reduce wear or collisions during use or assembly. This can effectively improve the stability and service life of the pressure relief mechanism, alleviate the phenomenon of premature valve opening and pressure relief due to damage to the pressure relief mechanism, and improve the reliability and service life of the battery cell.

[0023] In some embodiments, the surfaces of two adjacent bent segments facing the groove are connected by a first rounded corner surface; and / or, the surfaces of two adjacent bent segments facing away from the groove are connected by a second rounded corner surface; and / or, the plurality of bent segments include a first bent segment connected to the first portion, the surface of the first bent segment facing the groove being connected to the first surface by a third rounded corner surface; and / or, the plurality of bent segments include a first bent segment connected to the first portion, the surface of the first bent segment facing away from the groove being connected to the second surface by a fourth rounded corner surface.

[0024] In the above technical solution, by setting the surfaces of two adjacent bent sections facing the groove to be connected by a first rounded corner surface, the connection position of the surfaces of the two adjacent bent sections facing the groove has a rounded transition structure. Battery cells with this structure can mitigate the scraping or bumping of other components at the connection position of the surfaces of the two adjacent bent sections facing the groove, and can also reduce stress concentration at the connection position. Similarly, by setting the surfaces of two adjacent bent sections facing away from the groove to be connected by a second rounded corner surface, the connection position of the surfaces of the two adjacent bent sections facing away from the groove has a rounded transition structure. Battery cells with this structure can mitigate the scraping or bumping of other components at the connection position of the surfaces of the two adjacent bent sections facing away from the groove, and can also reduce stress concentration at the connection position. By configuring the surface of the first bent section facing the groove and the first surface of the first part to be connected via a third rounded corner surface, the connection point between the surface of the first bent section facing the groove and the first surface of the first part is a rounded transition structure. This structure in the battery cell can mitigate the scraping or bumping of other components at the connection point between the surface of the first bent section facing the groove and the first surface of the first part, and can also reduce stress concentration at this connection point. Similarly, by configuring the surface of the first bent section facing away from the groove and the second surface of the first part to be connected via a fourth rounded corner surface, the connection point between the surface of the first bent section facing away from the groove and the second surface of the first part is a rounded transition structure. This structure in the battery cell can also mitigate the scraping or bumping of other components at the connection point between the surface of the first bent section facing away from the groove and the second surface of the first part, and can also reduce stress concentration at this connection point.

[0025] In some embodiments, the wall thickness of the first portion is T1, and the wall thickness of the bent section is T2, satisfying that 0.8≤T2 / T1≤1.1.

[0026] In the above technical solution, the ratio of the wall thickness of the bent section to the wall thickness of the first part is 0.8 to 1.1. On the one hand, making the ratio of the wall thickness of the bent section to the wall thickness of the first part greater than or equal to 0.8 can improve the structural strength of the bent section, so as to alleviate the deformation or cracking of the bent section during use, which is conducive to improving the stability and reliability of the pressure relief mechanism. On the other hand, making the ratio of the wall thickness of the bent section to the wall thickness of the first part less than or equal to 1.1 can alleviate the excessive manufacturing difficulty of the second part bending to form multiple bent sections connected in sequence, so as to reduce the forming difficulty of the connection part.

[0027] In some embodiments, the wall thickness of the first portion is T1, satisfying 0.15mm≤T1≤0.5mm.

[0028] In the above technical solution, on the one hand, by setting the wall thickness of the first part of the connecting part to be greater than or equal to 0.15mm, the structural strength of the first part can be improved, thereby reducing the phenomenon of deformation or cracking of the first part during use, and improving the connection stability between the first part and the wall, which is beneficial to improving the stability and reliability of the battery cell. On the other hand, by setting the wall thickness of the first part of the connecting part to be less than or equal to 0.5mm, the space occupied by the first part in the thickness direction of the wall can be reduced, and the processing difficulty of the connecting part can be reduced.

[0029] In some embodiments, 0.2mm ≤ T1 ≤ 0.3mm.

[0030] In the above technical solution, on the one hand, by further setting the wall thickness of the first part of the connecting part to be greater than or equal to 0.2mm, the structural strength of the first part can be further improved, thereby further reducing the phenomenon of deformation or cracking of the first part during use, and further improving the connection stability between the first part and the wall, which is conducive to further improving the stability and reliability of the battery cell. On the other hand, by further setting the wall thickness of the first part of the connecting part to be less than or equal to 0.3mm, the space occupied by the first part in the thickness direction of the wall can be further optimized, and the processing difficulty of the connecting part can be further reduced.

[0031] In some embodiments, the plurality of bending segments include a first bending segment connected to the first portion and a second bending segment connected to the weak portion, wherein the wall thickness of the second bending segment is greater than the wall thickness of the first bending segment.

[0032] In the above technical solution, by setting the wall thickness of the second bending segment used to connect with the weak part to be greater than the wall thickness of the first bending segment used to connect with the first part, the structural strength of the area where the second part connects with the weak part is improved, and the buffering effect of the second part between the weak part and the first part is further improved. This helps to further reduce the stress transmitted to the weak part through the connection when the shell is subjected to impact or expansion, thereby further improving the fatigue resistance of the pressure relief mechanism and further reducing the risk of fatigue cracking in the weak part of the pressure relief mechanism during use.

[0033] In some embodiments, the minimum thickness of the weak portion along the thickness direction of the wall is D, satisfying 0.01mm≤D≤0.2mm.

[0034] In the above technical solution, on the one hand, setting the minimum thickness of the weak part in the thickness direction of the wall to be greater than or equal to 0.01mm can improve the structural strength of the weak part, so that the weak part is not prone to premature cracking due to pressure changes inside the battery cell or external impact, which helps to reduce the risk of the weak part being damaged prematurely and thus improve the life of the battery cell. On the other hand, setting the minimum thickness of the weak part in the thickness direction of the wall to be less than or equal to 0.2mm can reduce the burst pressure required by the pressure relief mechanism, so that the pressure relief mechanism can open in time to relieve pressure when the battery cell is thermally runaway, which helps to improve the timeliness of pressure relief mechanism and reduce the risk of battery cell bursting or exploding.

[0035] In some embodiments, the area of ​​the orthographic projection of the pressure relief zone in a projection plane perpendicular to the thickness direction of the wall is S; where 100mm 2 ≤450mm 2 And 0.01mm≤D≤0.16mm; or, 350mm 2 ≤S≤850mm 2 And 0.015mm≤D≤0.17mm; or, 750mm 2 ≤S≤1250mm 2 And 0.02mm≤D≤0.18mm; or, 1150mm 2 ≤S≤1650mm 2 And 0.025mm≤D≤0.19mm; or, 1550mm 2 ≤S≤2100mm 2 And 0.03mm≤D≤0.2mm.

[0036] In the above technical solution, when the projected area of ​​the pressure relief zone formed by the weak part is large, the pressure relief zone is more susceptible to internal pressure, causing the weak part to crack. Therefore, when the projected area of ​​the pressure relief zone increases, the thickness of the weak part can be increased to ensure the same burst pressure. For example, when the projected area is 100mm... 2 ≤S≤450mm 2 When D ≥ 0.01 mm, the thickness of the weak part is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts within the battery cell. This reduces the risk of premature damage to the weak part and helps extend the lifespan of the battery cell. When 100 mm... 2 ≤S≤450mm 2 When D≤0.16mm, the thickness of the weak part will not be too large, allowing the pressure relief mechanism to open and release pressure in a timely manner during thermal runaway of a single battery cell, thus improving the timeliness of pressure relief. Therefore, when 100mm 2 ≤S≤450mm 2When 0.01mm ≤ D ≤ 0.16mm, both the lifespan of the battery cell and the timeliness of pressure relief can be considered. When 350mm... 2 ≤S≤850mm 2 When D ≥ 0.015 mm, the thickness of the weak part is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts within the battery cell. This reduces the risk of premature damage to the weak part and improves the lifespan of the battery cell. When 350 mm... 2 ≤S≤850mm 2 When D≤0.17mm, the thickness of the weak part will not be too large, allowing the pressure relief mechanism to open and release pressure in a timely manner during thermal runaway of a single battery cell, thus improving the timeliness of pressure relief. Therefore, when 350mm 2 ≤S≤850mm 2 When 0.015mm ≤ D ≤ 0.17mm, both the lifespan of the battery cell and the timeliness of pressure relief can be considered. When 750mm... 2 ≤S≤1250mm 2 When D≥0.02mm, the thickness of the weak part is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts. This reduces the risk of premature damage to the weak part and improves the lifespan of the battery cell. When 750mm... 2 ≤S≤1250mm 2 When D≤0.18mm, the thickness of the weak part will not be too large, allowing the pressure relief mechanism to open and release pressure in a timely manner during thermal runaway of a single battery cell, thus improving the timeliness of pressure relief. Therefore, when 750mm 2 ≤S≤1250mm 2 When 0.02mm ≤ D ≤ 0.18mm, both the lifespan of the battery cell and the timeliness of pressure relief can be considered. When 1150mm... 2 ≤S≤1650mm 2 When D ≥ 0.025 mm, the thickness of the weak part is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts within the battery cell. This reduces the risk of premature damage to the weak part and improves the lifespan of the battery cell. When 1150 mm... 2 ≤S≤1650mm 2 When D≤0.19mm, the thickness of the weak part will not be too large, allowing the pressure relief mechanism to open and release pressure in a timely manner during thermal runaway of a single battery cell, thus improving the timeliness of pressure relief. Therefore, when 1550mm 2 ≤S≤2100mm 2 When 0.025mm ≤ D ≤ 0.19mm, both the lifespan of the battery cell and the timeliness of pressure relief can be considered. When 1550mm... 2 ≤S≤2100mm2 When D≥0.03mm, the thickness of the weak part is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts within the battery cell. This reduces the risk of premature damage to the weak part and improves the lifespan of the battery cell. When 1550mm... 2 ≤S≤2100mm 2 When D≤0.2mm, the thickness of the weak part will not be too large, allowing the pressure relief mechanism to open and release pressure in a timely manner during thermal runaway of a single battery cell, thus improving the timeliness of pressure relief. Therefore, when 1550mm 2 ≤S≤2100mm 2 Furthermore, when 0.03mm≤D≤0.2mm, both the lifespan of the battery cell and the timeliness of pressure relief can be taken into account.

[0037] In some embodiments, the weak portion includes a first weak segment and a second weak segment connected end to end, and along the thickness direction of the wall portion, the thickness of the second weak segment is greater than the thickness of the first weak segment.

[0038] In the above technical solution, by setting the thickness of the second weak segment of the weak part in the wall thickness direction to be greater than the thickness of the first weak segment of the weak part in the wall thickness direction, the structural strength of the second weak segment is greater than that of the first weak segment. This allows the first weak segment to crack first compared to the second weak segment when the battery cell is depressurized, so that the depressurization area of ​​the depressurization mechanism located inside the weak part can be flipped around the second weak segment as the axis and open to depressurize. This helps to improve the depressurization smoothness of the depressurization mechanism of the battery cell and thus improve the timeliness of depressurization of the battery cell.

[0039] In some embodiments, the weak portion includes two arc segments and two straight segments, one arc segment, one straight segment, another arc segment, and another straight segment are connected end to end, the two arc segments are arranged opposite each other along a first direction and extend along an arc trajectory, the two straight segments are arranged opposite each other along a second direction and extend along the first direction, the first direction, the second direction, and the thickness direction of the wall are perpendicular to each other; wherein, the first weak portion includes two arc segments and one straight segment, and the second weak portion is the other straight segment.

[0040] In the above technical solution, the first weak segment includes two arc segments and one straight segment, and the second weak segment is another straight segment of the weak part. The arc segment, the straight segment, the arc segment, and the straight segment are connected end to end in sequence. By setting the two arc segments to extend along the arc trajectory and being arranged opposite each other in the first direction, and setting the two straight segments to extend along the first direction and being arranged opposite each other in the second direction, the battery cell with this structure can, on the one hand, facilitate the forming of the first and second weak segments with different thicknesses on the pressure relief mechanism, which helps to reduce the processing difficulty of the pressure relief mechanism. On the other hand, it can further improve the smoothness of the pressure relief area located inside the weak part of the pressure relief mechanism after the first weak segment cracks and flips around the second weak segment as the axis. It also helps to further expand the flipping angle of the pressure relief area located inside the weak part of the pressure relief mechanism, so as to further improve the pressure relief smoothness and pressure relief rate of the battery cell.

[0041] In some embodiments, at least a portion of the pressure relief area bulges toward or away from the electrode assembly along the thickness direction of the wall portion, forming a raised portion, and the weak portion surrounds the outside of the raised portion.

[0042] In the above technical solution, by setting a raised portion on the pressure relief area inside the weak part, which bulges towards or away from the electrode assembly, and the weak part surrounds the outside of the raised portion, the battery cell with this structure can, on the one hand, reduce the difficulty of forming the weak part in the pressure relief mechanism and improve the material flow pattern of the weak part during processing, thereby improving the processing consistency of the weak part. On the other hand, it can improve the structural strength of the pressure relief area inside the weak part, which can help alleviate the deformation and damage of the pressure relief area inside the weak part during use. Moreover, the raised portion inside the weak part forms a pre-deformed structure, which allows the weak part of the pressure relief mechanism to crack and relieve pressure. Thus, under the same burst pressure, the thickness of the weak part can be increased to alleviate fatigue cracking of the weak part during use. This can effectively reduce the risk of premature valve opening of the pressure relief mechanism, thereby improving the service life and reliability of the battery cell.

[0043] In some embodiments, at least a portion of the boundary of the raised portion is adjacent to the boundary of the weak portion.

[0044] In the above technical solution, by having at least a portion of the boundary of the raised portion adjacent to the boundary of the weak portion, the raised portion can directly pull the weak portion through the adjacent portion when the battery cell is depressurized. This results in a greater shear force on the portion adjacent to the boundary of the raised portion and facilitates the cracking and depressurization of the weak portion. Under the same burst pressure, the thickness of the weak portion can be increased to alleviate fatigue cracking and other phenomena that occur during use. This effectively reduces the risk of premature valve opening in the depressurization mechanism, thereby improving the service life and reliability of the battery cell.

[0045] In some embodiments, the first portion has opposing first and second surfaces in the thickness direction of the wall portion, the second portion protrudes from the second surface in a direction pointing from the first surface to the second surface, the pressure relief mechanism is provided with a groove, the groove is recessed from the first surface in a direction pointing from the first surface to the second surface, the second portion, the weak portion and the pressure relief area together enclose at least a portion of the groove; wherein, in the thickness direction of the wall portion, the protruding portion protrudes in a direction pointing from the second surface to the first surface.

[0046] In the above technical solution, the pressure relief mechanism is provided with a groove recessed from the first surface in the direction pointing from the first surface to the second surface. The second part, the weak part, and the pressure relief area together enclose at least part of the groove, and the raised part is a structure that bulges in the direction pointing from the second surface to the first surface. The battery cell with this structure can achieve different bulging directions of the raised part and the second part, which is beneficial to improve the overall structural strength of the pressure relief mechanism and reduce the risk of fatigue cracking or damage during use. It can also achieve that the raised part and the second part share a part of the space in the thickness direction of the wall, which is beneficial to save the space occupied by the pressure relief mechanism and improve the space utilization of the battery cell. On the other hand, it can achieve that the raised part is a structure that bulges towards the groove, so that the groove can also play a certain protective role for the raised part, reducing wear or bumps during use or assembly.

[0047] In some embodiments, in the thickness direction of the wall portion, the raised portion does not extend beyond the first surface in the direction from the second surface to the first surface.

[0048] In the above technical solution, by setting the first bulge to be a structure that does not extend beyond the first surface in the direction from the second surface to the first surface, it is beneficial to further improve the protection effect of the bulge, thereby further reducing wear or bumps on the bulge during use or assembly, and thus improving the reliability and service life of the pressure relief mechanism.

[0049] In some embodiments, the raised portion includes a first region and two second regions, the two second regions being spaced apart along a first direction and respectively connected to both ends of the first region, the outer surface of the raised portion being recessed to form a recessed area, the recessed direction of the recessed area being opposite to the raised direction of the raised portion, and the recessed area being located within the first region, the first direction being perpendicular to the thickness direction of the wall portion.

[0050] In the above technical solution, the raised portion includes two second regions arranged along a first direction and a first region connected between the two second regions. A recessed area is formed on the outer surface of the raised portion in the opposite direction to the raised direction of the raised portion, and the recessed area is located within the first region. This makes the pressure relief area of ​​the pressure relief mechanism located inside the weak part a structure that is both concave and convex, thereby improving the structural strength and fatigue resistance of the pressure relief area of ​​the pressure relief mechanism located inside the weak part, thereby improving the overall structural strength of the pressure relief mechanism. This further reduces the strain and strain amplitude of the pressure relief mechanism when the outer shell is subjected to impact or expansion, thereby further reducing the risk of fatigue cracking in the weak part of the pressure relief mechanism during use. This further alleviates the phenomenon of premature valve opening and pressure relief in the pressure relief mechanism, which is conducive to further improving the reliability and service life of the battery cell.

[0051] In some embodiments, the weak portion includes two arc segments and two straight segments, one arc segment, one straight segment, another arc segment, and another straight segment being connected end to end in sequence. The two arc segments are arranged opposite each other along the first direction and extend along an arc trajectory. The two straight segments are arranged opposite each other along the second direction and extend along the first direction. The first direction, the second direction, and the thickness direction of the wall are perpendicular to each other. The areas where the raised portion connects with the two arc segments are the two second areas, and the areas where the raised portion connects with the two straight segments are the first areas.

[0052] In the above technical solution, the weak part is configured as including two arc segments arranged opposite each other along a first direction and two straight segments arranged opposite each other along a second direction, with each end of the straight segment connected to one end of the two arc segments, to form a ring-shaped weak part. The areas where the raised part is connected to the two arc segments are the two second areas of the raised part, and the areas where the raised part is connected to the two straight segments are the first area of ​​the raised part, to form a first area connected between the two second areas in the first direction. The pressure relief mechanism with this structure is convenient to form a recessed area on the first area of ​​the raised part that is opposite to the raised direction of the raised part, which helps to reduce the molding difficulty of the pressure relief mechanism.

[0053] In some embodiments, in a projection plane perpendicular to the thickness direction of the wall, the orthographic projection of the first region is rectangular, and the orthographic projection of the second region is semi-circular.

[0054] In the above technical solution, by setting the projection of the first region in the thickness direction of the wall to a rectangular structure and setting the projection of the second region in the thickness direction of the wall to a semi-circular structure, the raised portion forms the first region between the two second regions, and can further improve the regularity of the shape of the raised portion, thereby further reducing the difficulty of forming a recessed area in the first region, so as to further reduce the molding difficulty of the pressure relief mechanism.

[0055] In some embodiments, along the thickness direction of the wall portion, the maximum recess depth of the recessed area is H, satisfying 0.05mm≤H≤1mm.

[0056] In the above technical solution, on the one hand, setting the maximum recessed depth of the recessed area in the thickness direction of the wall to be greater than or equal to 0.05mm can enhance the strengthening effect of the recessed area on the structural strength of the raised part, thereby improving the structural strength and fatigue resistance of the pressure relief area located inside the weak part of the pressure relief mechanism, which is conducive to improving the overall structural strength of the pressure relief mechanism. On the other hand, setting the maximum recessed depth of the recessed area in the thickness direction of the wall to be less than or equal to 1mm can reduce the difficulty of forming the recessed area on the first region of the raised part, thereby reducing the manufacturing difficulty of the pressure relief mechanism.

[0057] In some embodiments, 0.1mm ≤ H ≤ 0.5mm.

[0058] In the above technical solution, on the one hand, setting the maximum recessed depth of the recessed area in the thickness direction of the wall to be greater than or equal to 0.1 mm can further enhance the strengthening effect of the recessed area on the structural strength of the raised part, thereby further improving the structural strength and fatigue resistance of the pressure relief area located inside the weak part of the pressure relief mechanism, which is conducive to further improving the overall structural strength of the pressure relief mechanism. On the other hand, setting the maximum recessed depth of the recessed area in the thickness direction of the wall to be less than or equal to 0.5 mm can further reduce the difficulty of forming the recessed area on the first region of the raised part, thereby further reducing the manufacturing difficulty of the pressure relief mechanism.

[0059] In some embodiments, the maximum dimension of the second region in the thickness direction of the wall is L2, satisfying 0.5mm≤L2≤3mm.

[0060] In the above technical solution, on the one hand, by setting the maximum dimension of the second region of the raised portion in the thickness direction of the wall to be greater than or equal to 0.5 mm, the strengthening effect of the raised portion on the structural strength of the pressure relief mechanism can be improved, thereby enhancing the structural strength and fatigue resistance of the pressure relief area located inside the weak part of the pressure relief mechanism. This is beneficial to improving the overall structural strength of the pressure relief mechanism and facilitates the formation of the weak part on the outside of the raised portion, which is beneficial to improving the material flow pattern of the weak part during the processing, thereby improving the processing consistency of the weak part. On the other hand, setting the maximum dimension of the second region of the raised portion in the thickness direction of the wall to be less than or equal to 3 mm can reduce the difficulty of forming the raised portion on the pressure relief area inside the weak part, thereby reducing the manufacturing difficulty of the pressure relief mechanism and mitigating the risk of breakage or cracking of the raised portion during the forming process, thereby improving the processing quality of the pressure relief mechanism.

[0061] In some embodiments, 0.7mm ≤ L2 ≤ 1.6mm.

[0062] In the above technical solution, on the one hand, by further setting the maximum dimension of the second region of the raised portion in the thickness direction of the wall to be greater than or equal to 0.7 mm, the strengthening effect of the raised portion on the structural strength of the pressure relief mechanism can be further improved, thereby further improving the structural strength and fatigue resistance of the pressure relief area located inside the weak part of the pressure relief mechanism. This is beneficial to further improve the overall structural strength of the pressure relief mechanism and can further reduce the difficulty of forming the weak part on the outside of the raised portion. This is beneficial to further improve the material flow pattern of the weak part during the processing, thereby further improving the processing consistency of the weak part. On the other hand, by further setting the maximum dimension of the second region of the raised portion in the thickness direction of the wall to be less than or equal to 1.6 mm, the difficulty of forming the raised portion on the pressure relief area inside the weak part can be further reduced, thereby further reducing the manufacturing difficulty of the pressure relief mechanism and further mitigating the risk of breakage or cracking of the raised portion during the forming process, thereby further improving the processing quality of the pressure relief mechanism.

[0063] In some embodiments, the pressure relief mechanism is provided with a pressure relief groove, and the bottom wall of the pressure relief groove forms the weak part.

[0064] In the above technical solution, a weak part is formed on the pressure relief mechanism by opening a pressure relief groove, so that the pressure relief mechanism can crack along at least a part of the weak part when the battery cell is depressurized. This reduces the difficulty of forming the weak part on the pressure relief mechanism, and the structure is simple and easy to manufacture.

[0065] In some embodiments, the pressure relief mechanism is separately disposed from the wall portion; or, the pressure relief mechanism is integrally formed with the wall portion.

[0066] In the above technical solution, by setting the pressure relief mechanism and the wall as separate components, the weak points and connecting parts can be machined on the pressure relief mechanism first, and the second part of the connecting part can be bent into multiple connected bent segments before the pressure relief mechanism is assembled onto the wall of the outer casing. This reduces the molding difficulty of the pressure relief mechanism and optimizes the production cycle of the battery cell. Alternatively, by setting the pressure relief mechanism and the wall as an integrally formed structure, the battery cell with this structure can improve the structural strength of the pressure relief mechanism connected to the wall, reducing the risk of the pressure relief mechanism detaching during use, thereby improving the stability and reliability of the battery cell.

[0067] Secondly, embodiments of this application also provide a battery device, including the aforementioned battery cell.

[0068] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned battery cell, wherein the battery cell is used to provide electrical energy. Attached Figure Description

[0069] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0071] Figure 2 is an exploded view of the structure of a battery device provided in some embodiments of this application;

[0072] Figure 3 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0073] Figure 4 is an exploded view of the structure of a battery cell provided in some embodiments of this application;

[0074] Figure 5 is a cross-sectional view of a pressure relief mechanism provided in some embodiments of this application, perpendicular to the second direction;

[0075] Figure 6 is a partial enlarged view of point A of the pressure relief mechanism shown in Figure 5;

[0076] Figure 7 is a front view of the pressure relief mechanism provided in some embodiments of this application in the thickness direction of the wall portion;

[0077] Figure 8 is a cross-sectional view of a pressure relief mechanism provided in some embodiments of this application, perpendicular to a first direction.

[0078] Icons: 1000 - Vehicle; 100 - Battery assembly; 10 - Housing; 11 - First housing body; 12 - Second housing body; 20 - Battery cell; 21 - Casing; 211 - Wall; 212 - Housing; 2121 - Opening; 213 - End cap; 22 - Electrode assembly; 221 - Tab; 23 - Pressure relief mechanism; 231 - Weak section; 231a - First weak section; 231b - Second weak section; 2311 - Curved section; 2312 - Straight section; 232 - Connection part; 2321 - First part; 2321a - First surface; 2321b - Second surface; 232 2-Second part; 2322a-Bent section; 2322b-First bent section; 2322c-Second bent section; 2323-First rounded corner surface; 2324-Second rounded corner surface; 2325-Third rounded corner surface; 2326-Fourth rounded corner surface; 233-Raised portion; 2331-First region; 2331a-Recessed region; 2332-Second region; 234-Pressure relief groove; 235-Pressure relief region; 236-Groove; 24-Electrode terminal; 25-Current collector; 200-Controller; 300-Motor; X-Thickness direction of the wall; Y-First direction; Z-Second direction. Detailed Implementation

[0079] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0080] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0081] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0082] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0083] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0084] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0085] In this application, "multiple" means two or more (including two).

[0086] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0087] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0088] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, helps prevent short circuits to some extent while allowing active ions to pass through.

[0089] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0090] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0091] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0092] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds.

[0093] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0094] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0095] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0096] 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.

[0097] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0098] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0099] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0100] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0101] In some embodiments, the separator is a separator membrane. The separator membrane can be of various types, and any known porous separator membrane with good chemical and mechanical stability can be selected.

[0102] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0103] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0104] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0105] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0106] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0107] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0108] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0109] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0110] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0111] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0112] In some implementations, the electrode assembly has a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0113] In some implementations, the electrode assembly has a stacked structure.

[0114] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0115] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0116] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0117] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0118] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0119] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0120] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0121] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0122] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include, but are not limited to, square battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0123] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0124] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0125] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0126] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0127] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0128] As an example, the enclosure may include a first enclosure body and a second enclosure body. The first enclosure body and the second enclosure body are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, which can be either sealed or unsealed. The first enclosure body may be a top cover or a bottom plate.

[0129] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0130] As an example, the housing can be part of the vehicle's chassis structure. For instance, the housing's roof can be at least part of the vehicle's floor, or the housing's frame can be at least part of the vehicle's crossbeams and longitudinal beams.

[0131] In some embodiments, the battery device refers to an energy storage device, which includes a housing with a door on at least one side. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0132] Battery devices possess outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide applicability, and low self-discharge coefficient, making them an important component of today's new energy development. The development of battery technology must simultaneously consider multiple design factors, such as performance parameters like energy density, cycle life, discharge capacity, and charge / discharge rate. Furthermore, the reliability of the battery device must also be taken into account.

[0133] To ensure the safety of a typical battery cell, a pressure relief mechanism is usually installed on its casing. This mechanism releases the internal pressure of the battery cell, thereby effectively improving its safety. In related technologies, pressure relief mechanisms are typically flat plate structures. By stamping pressure relief grooves onto the mechanism, it can crack along the area where the pressure relief groove is located when the battery cell is depressurized, thus releasing the internal pressure of the battery cell. However, existing pressure relief mechanisms for battery cells have poor fatigue resistance under the same burst pressure conditions. This means that the stress generated by the impact or expansion of the battery cell casing during use is transmitted to the area where the pressure relief groove is located in the pressure relief mechanism. This is especially true for steel pressure relief mechanisms and structures where the pressure relief mechanism is welded to the casing. The stress generated by the impact or expansion of the casing and the stress generated by the welded connection between the pressure relief mechanism and the casing are directly transmitted and act on the pressure relief mechanism. This results in large strain and strain amplitude on the pressure relief mechanism on the casing, leading to fatigue cracking risks in the area where the pressure relief groove is located. Consequently, the pressure relief mechanism is prone to premature valve opening and pressure release, which is detrimental to improving the service life and reliability of the battery cell.

[0134] Based on the above considerations, in order to solve the problems of low reliability and short service life of battery cells, this application provides a battery cell including a casing, an electrode assembly, and a pressure relief mechanism. The casing has a wall. The electrode assembly is housed within the casing. The pressure relief mechanism is disposed in the wall and includes a weak portion and a connecting portion. The weak portion is configured to be at least partially destroyed to release pressure when the pressure inside the casing reaches a threshold. The weak portion is annular, and the area enclosed by the weak portion is a pressure relief zone. The connecting portion includes a first part and a second part. The first part is connected to the wall, and the second part is connected to the weak portion and the first part. The second part is bent to form a plurality of sequentially connected bent segments. The bent segments surround the outside of the weak portion, and the bent segments at both ends of the plurality of bent segments are respectively connected to the first part and the weak portion.

[0135] In this type of battery cell, a pressure relief mechanism is provided on the wall of the outer casing. This mechanism has a weak point, which is configured to at least partially break down when the internal pressure reaches a threshold, thus releasing the internal pressure of the battery cell and reducing the risk of rupture or explosion during use. Specifically, the connection is configured as a first part and a second part that are interconnected. The first part is connected to the wall, and the second part is bent to form multiple sequentially connected bent segments. These bent segments surround the weak point, and the bent segments at both ends connect to the first part and the weak point, respectively. The weak part is connected to the first part through a second part. With this structure, the battery cell can act as a buffer between the first part and the weak part through the second part. This allows the second part to alleviate the stress generated by the outer shell when it is subjected to impact or expansion, which is transmitted to the weak part through the connection. This helps to improve the fatigue resistance of the pressure relief mechanism, thereby effectively reducing the strain and strain amplitude of the weak part during use. This reduces the risk of fatigue cracking in the weak part of the pressure relief mechanism during use, and further alleviates the phenomenon of premature valve opening and pressure relief in the pressure relief mechanism. This helps to improve the reliability and service life of the battery cell.

[0136] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system comprising the battery cells and battery devices disclosed in this application can be used to construct such an electrical device. This helps to alleviate the problem of premature pressure release in the battery cell's pressure relief mechanism during use, thereby improving the battery cell's lifespan and reliability.

[0137] This application provides an electrical device that uses a single battery cell or battery assembly as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0138] For ease of explanation, the following embodiments will be described using a vehicle as an example of an electrical device according to an embodiment of this application.

[0139] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside the vehicle 1000. The battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, it can serve as the vehicle's operating power source or general power source. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 controls the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0140] In some embodiments of this application, the battery device 100 can not only serve as the operating power or power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0141] Please refer to Figures 2 and 3. Figure 2 is an exploded view of the structure of a battery device 100 provided in some embodiments of this application, and Figure 3 is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of this application. The battery device 100 includes a housing 10 and a battery cell 20, which is housed within the housing 10.

[0142] The housing 10 provides assembly space for the battery cell 20, and can adopt various structures. In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, which overlap each other, and together define an assembly space for accommodating the battery cell 20. The second housing body 12 may be a hollow structure open at one end, and the first housing body 11 may be a plate-like structure, with the first housing body 11 covering the open side of the second housing body 12 so that the first housing body 11 and the second housing body 12 together define the assembly space; alternatively, the first housing body 11 and the second housing body 12 may both be hollow structures open on one side, with the open side of the first housing body 11 covering the open side of the second housing body 12.

[0143] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder, a cuboid, or a cube. For example, in Figure 2, the shape of the box 10 is a cuboid.

[0144] In the battery device 100, there can be one or more battery cells 20 disposed within the housing 10. When there are multiple battery cells 20 disposed within the housing 10, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, in parallel, or in a mixed configuration to form battery modules, and then multiple battery modules are connected in series, in parallel, or in a mixed configuration to form a whole, which is then housed within the housing 10.

[0145] In some embodiments, the battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar for connecting multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0146] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 20 can be in the form of a cuboid, cylinder, prism, or other shapes. For example, in Figure 3, the battery cell 20 has a cuboid structure.

[0147] According to some embodiments of this application, referring to FIG3, and further referring to FIG4, 5, 6 and 7, FIG4 is an exploded view of the structure of a battery cell 20 provided in some embodiments of this application, FIG5 is a cross-sectional view of a pressure relief mechanism 23 provided in some embodiments of this application perpendicular to the second direction Z, FIG6 is a partial enlarged view of point A of the pressure relief mechanism 23 shown in FIG5, and FIG7 is a front view of the pressure relief mechanism 23 provided in some embodiments of this application in the thickness direction X of the wall portion. This application provides a battery cell 20, which includes a housing 21, an electrode assembly 22 and a pressure relief mechanism 23. The housing 21 has a wall portion 211. The electrode assembly 22 is accommodated within the housing 21. A pressure relief mechanism 23 is disposed on the wall portion 211. The pressure relief mechanism 23 includes a weak portion 231 and a connecting portion 232. The weak portion 231 is configured to be at least partially destroyed to release pressure when the pressure inside the housing 21 reaches a threshold. The weak portion 231 is annular, and the area enclosed by the weak portion 231 is a pressure relief zone 235. The connecting portion 232 includes a first part 2321 and a second part 2322. The first part 2321 is connected to the wall portion 211, and the second part 2322 connects the weak portion 231 and the first part 2321. The second part 2322 is bent to form a plurality of sequentially connected bent segments 2322a. The bent segments 2322a surround the outside of the weak portion 231, and the bent segments 2322a at both ends of the plurality of bent segments 2322a are respectively connected to the first part 2321 and the weak portion 231.

[0148] The outer shell 21 can also be used to contain electrolytes, such as electrolyte solution. The outer shell 21 can have various structural forms, such as a cylinder, cuboid, or prism. Similarly, the outer shell 21 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy.

[0149] In some embodiments, the housing 21 may include a housing 212 and an end cap 213. The housing 212 has an internal cavity for accommodating the electrode assembly 22 and has an opening 2121. That is, the housing 212 is a hollow structure with an opening 2121 at one end. The end cap 213 covers the opening 2121 of the housing 212 and forms a sealed connection to form a closed space for accommodating the electrode assembly 22 and the electrolyte.

[0150] The housing 212 includes an integrally formed side wall and a bottom wall. The side wall surrounds the bottom wall, one end of the side wall is connected to the bottom wall, and the other end forms an opening 2121. The bottom wall and the end cap 213 are disposed opposite each other. The side wall and the bottom wall together define a receiving cavity, in which the electrode assembly 22 is received.

[0151] It should be noted that the wall portion 211 provided with the pressure relief mechanism 23 can be the end cap 213 of the outer casing 21, or it can be one of the multiple walls of the bottom wall or side wall of the casing 212. For example, in Figures 3 and 4, the wall portion 211 is the bottom wall of the casing 212, and the pressure relief mechanism 23 is provided on a wall of the casing 212 that is opposite to the end cap 213 in the thickness direction X of the wall portion. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the wall portion 211 can also be the end cap 213, etc.

[0152] When assembling the battery cell 20, the electrode assembly 22 can be placed into the housing 212 first, and the electrolyte can be filled into the housing 212. Then, the end cap 213 can be closed onto the opening 2121 of the housing 212 to complete the assembly of the battery cell 20.

[0153] The housing 212 can have various shapes, such as a cylinder, cuboid, or prism. The shape of the housing 212 can be determined according to the specific shape of the electrode assembly 22. For example, if the electrode assembly 22 is a cylindrical structure, a cylindrical housing 212 can be selected; if the electrode assembly 22 is a cuboid structure, a cuboid housing 212 can be selected. Of course, the end cap 213 can also have various structures, such as a plate-like structure or a hollow structure with one end open.

[0154] Of course, it is understandable that the outer casing 21 is not limited to the structure described above. The outer casing 21 can also be other structures. For example, the outer casing 21 can include a housing 212 and two end caps 213. The housing 212 is a hollow structure with openings 2121 on opposite sides. One end cap 213 is fitted onto one opening 2121 of the housing 212 and forms a sealed connection to form a closed space for accommodating the electrode assembly 22 and the electrolyte. That is, the housing 212 has openings 2121 on opposite sides, and the two end caps 213 are fitted onto the opposite sides of the housing 212 to close the corresponding openings 2121.

[0155] It should be noted that the electrode assembly 22 is the component in the battery cell 20 where the electrochemical reaction occurs. The structure of the electrode assembly 22 can be various. For example, the electrode assembly 22 can be a wound structure formed by winding the positive electrode, the separator and the negative electrode, or a stacked structure formed by arranging the positive electrode, the separator and the negative electrode in layers.

[0156] For example, the separator is a separator membrane, and the main material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0157] Optionally, the electrode assembly 22 housed within the housing 21 can be one or more. For example, in Figure 4, two electrode assemblies 22 are disposed within the housing 21 of the battery cell 20. The two electrode assemblies 22 are stacked along their thickness direction, that is, the two electrode assemblies 22 are stacked along the thickness direction of the battery cell 20. The length direction of the battery cell 20 is the first direction Y, the thickness direction of the battery cell 20 is the second direction Z, and the height direction of the battery cell 20 is the thickness direction X of the wall portion. The thickness direction X of the wall portion, the first direction Y, and the second direction Z are all perpendicular to each other. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the electrode assembly 22 housed within the housing 21 can also be one, three, four, five, six, seven, or eight, etc.

[0158] In some embodiments, as shown in Figures 3 and 4, the battery cell 20 may further include an electrode terminal 24, which is insulated and mounted on the housing 21. One end of the electrode assembly 22 is formed with a tab 221, and the electrode terminal 24 is electrically connected to the tab 221 of the electrode assembly 22 to output or input electrical energy of the battery cell 20.

[0159] It should be noted that the electrode terminal 24 is insulated and mounted on the housing 21, meaning that there is no electrical connection between the electrode terminal 24 and the housing 21.

[0160] In Figures 3 and 4, the battery cell 20 includes two electrode terminals 24, which are spaced apart along the first direction Y on the end cap 213. Correspondingly, each electrode assembly 22 has two tabs 221 with opposite polarities. The two tabs 221 are spaced apart along the first direction Y and are both located at the end of the electrode assembly 22 facing the end cap 213. The two electrode terminals 24 are electrically connected to the two tabs 221 of the electrode assembly 22 to realize the input or output of electrical energy of the battery cell 20. It should be noted that the tabs 221 of the electrode assembly 22 are formed by stacking and connecting the regions of the positive electrode sheet that are not coated with a positive active material layer or the regions of the negative electrode sheet that are not coated with a negative active material layer. If tab 221 is the positive tab 221 of electrode assembly 22, then tab 221 is a component formed by stacking and connecting the regions on the positive electrode sheet that are not coated with the positive active material layer; if tab 221 is the negative tab 221 of electrode assembly 22, then tab 221 is a component formed by stacking and connecting the regions on the negative electrode sheet that are not coated with the negative active material layer.

[0161] For example, the electrode terminal 24 can be made of various materials, such as copper, iron, aluminum, steel or aluminum alloy.

[0162] Optionally, the structure in which the electrode terminals 24 are mounted on the housing 21 can be varied. For example, in Figures 3 and 4, both electrode terminals 24 are mounted on the end cap 213 of the housing 21. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the battery cell 20 can also have other structures. For example, both electrode terminals 24 can be mounted on the housing 212 of the housing 21. Similarly, one electrode terminal 24 can be mounted on the housing 212 of the housing 21, and the other electrode terminal 24 can be mounted on the end cap 213 of the housing 21.

[0163] In some embodiments, as shown in FIG4, the battery cell 20 may further include two current collectors 25. Both current collectors 25 are disposed inside the housing 21 and are spaced apart along the first direction Y. Each current collector 25 is used to connect an electrode terminal 24 and a tab 221 of the same polarity in a plurality of electrode assemblies 22 to realize the electrical connection between the electrode terminal 24 and the electrode assembly 22, which helps to reduce the assembly difficulty between the tab 221 and the electrode terminal 24.

[0164] For example, the material of the current collector 25 can be various, such as copper, iron, aluminum, steel or aluminum alloy.

[0165] In this embodiment, the pressure relief mechanism 23 plays a pressure relief role in the battery cell 20, and is used to release the internal pressure of the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value.

[0166] The pressure relief mechanism 23 is disposed on the wall portion 211. The pressure relief mechanism 23 and the wall portion 211 can be integrally formed or separately disposed. For example, in Figure 4, the pressure relief mechanism 23 and the wall portion 211 are separately disposed. Correspondingly, the wall portion 211 is provided with a pressure relief hole. The pressure relief mechanism 23 is connected to the wall portion 211 and the pressure relief mechanism 23 blocks the pressure relief hole. That is, the pressure relief mechanism 23 is assembled on the wall portion 211 and blocks and covers the pressure relief hole. The pressure relief hole penetrates the wall portion 211 and connects the inside and outside of the outer shell 21, so that when the pressure relief mechanism 23 is actuated and cracked, the inside and outside of the outer shell 21 can be interconnected to release the internal pressure of the battery cell 20. Similarly, in the embodiment where the pressure relief mechanism 23 and the wall portion 211 are separately disposed but connected, the structure of the pressure relief mechanism 23 connected to the wall portion 211 can also be various, such as welding connection, snap-fit ​​or adhesive connection.

[0167] Referring to Figures 5, 6 and 7, the pressure relief mechanism 23 includes a weak portion 231 and a connecting portion 232. The connecting portion 232 is a structure that connects the weak portion 231 and the wall portion 211 of the pressure relief mechanism 23. The weak portion 231 is configured to be at least partially destroyed to release pressure when the pressure inside the housing 21 reaches a threshold. That is, the pressure relief mechanism 23 is configured to be able to crack along at least a portion of the weak portion 231 when the battery cell 20 is depressurized, so as to release the internal pressure of the battery cell 20.

[0168] For example, the pressure relief mechanism 23 has a pressure relief groove 234 on at least one side of its wall surface in the thickness direction X, and the bottom wall of the pressure relief groove 234 forms a weak portion 231. For example, the pressure relief groove 234 is provided on the surface of the pressure relief mechanism 23 on the side of its wall surface facing away from the electrode assembly 22 in the thickness direction X, and the pressure relief groove 234 on the pressure relief mechanism 23 is a groove structure formed by a stamping process.

[0169] The weak part 231 is annular, that is, the weak part 231 is an annular structure with the ends connected. Correspondingly, the pressure relief groove 234 is an annular groove structure with the ends connected.

[0170] The area enclosed by the weak part 231 is the pressure relief area 235. That is, the area inside the weak part 231 of the annular structure where the pressure relief mechanism 23 is located is the pressure relief area 235. The pressure relief area 235 is the area enclosed by the weak part 231 in the pressure relief mechanism 23. In other words, the pressure relief area 235 is the part of the pressure relief mechanism 23 located inside the weak part 231, so that when the battery cell 20 is depressurized, the weak part 231 can crack along the edge of the pressure relief area 235 to open the pressure relief area 235 for pressure relief. Correspondingly, the weak part 231 surrounds the outside of the pressure relief area 235.

[0171] The connecting portion 232 includes a first portion 2321 and a second portion 2322. The first portion 2321 is connected to the wall portion 211, and the second portion 2322 surrounds the outside of the weak portion 231 and connects the weak portion 231 and the first portion 2321. That is, the connecting portion 232 includes a first portion 2321 and a second portion 2322 that are connected to each other. The first portion 2321 is the area where the connecting portion 232 is connected to the wall portion 211, and the second portion 2322 is the area where the connecting portion 232 is connected to the weak portion 231. The second portion 2322 is an annular structure that surrounds the outside of the weak portion 231, so that the second portion 2322 is connected between the first portion 2321 and the weak portion 231.

[0172] For example, the first part 2321 is a flat plate structure, and the thickness direction of the first part 2321 is parallel to the thickness direction X of the wall.

[0173] It should be noted that in the embodiment where the pressure relief mechanism 23 and the wall portion 211 are integrally formed, the first part 2321 is a part of the wall portion 211, and the second part 2322 and the weak part 231 are structures formed on the wall portion 211 by an integral forming process. In the embodiment where the pressure relief mechanism 23 and the wall portion 211 are separately set, the first part 2321 and the wall portion 211 are connected to each other, and the connection structure can be a welding connection or the like.

[0174] The second part 2322 is bent to form a plurality of sequentially connected bent segments 2322a. The bent segments 2322a surround the outside of the weak part 231. That is to say, the second part 2322 is a structure of partial bending, so that the second part 2322 forms a plurality of sequentially connected bent segments 2322a. Each pair of adjacent bent segments 2322a can be set at an acute angle, a right angle or an obtuse angle, and each bent segment 2322a is a structure that surrounds the outside of the weak part 231. That is, the plurality of bent segments 2322a are a structure that surrounds the outside of the weak part 231 in sequence.

[0175] Among the multiple bends 2322a, the bends 2322a located at both ends are connected to the first part 2321 and the weak part 231 respectively. That is to say, the first part 2321, the multiple bends 2322a and the weak part 231 are connected in sequence.

[0176] For example, in FIG6, the second part 2322 is bent to form two interconnected bent segments 2322a, which are respectively connected to the first part 2321 and the weak part 231. Of course, in other embodiments, the number of bent segments 2322a formed by the bending of the second part 2322 can also be three, four, five or six, etc.

[0177] In this embodiment, a pressure relief mechanism 23 is provided on the wall 211 of the outer casing 21. The pressure relief mechanism 23 has a weak portion 231, which is configured to be at least partially destroyed when the pressure inside the outer casing 21 reaches a threshold to release the pressure, thereby releasing the internal pressure of the battery cell 20 and reducing the risk of the battery cell 20 bursting or exploding during use. The connecting portion 232 is configured as a first part 2321 and a second part 2322 that are interconnected. The first part 2321 is connected to the wall 211, and the second part 2322 is configured as a structure formed by bending to form a plurality of sequentially connected bent segments 2322a. The bent segments 2322a are arranged around the weak portion 231, such that the bent segments 2322a at both ends of the plurality of bent segments 2322a are respectively connected to the first part. The battery cell 20 with this structure uses the second part 2322 to connect the first part 2321 and the weak part 2321. The second part 2322 can play a certain buffering role between the first part 2321 and the weak part 231, so that the second part 2322 can alleviate the phenomenon that the stress generated by the outer shell 21 when it is subjected to impact or expansion is transmitted to the weak part 231 through the connection part 232. This is beneficial to improving the fatigue resistance of the pressure relief mechanism 23, thereby effectively reducing the strain and strain amplitude of the weak part 231 during use, reducing the risk of fatigue cracking of the weak part 231 during use, and thus alleviating the phenomenon of premature valve opening and pressure relief of the pressure relief mechanism 23. This is beneficial to improving the reliability and service life of the battery cell 20.

[0178] According to some embodiments of this application, referring to Figures 5 and 6, the first portion 2321 has opposing first surfaces 2321a and second surfaces 2321b in the thickness direction X of the wall portion, and the second portion 2322 protrudes from and out of the second surface 2321b along the direction from the first surface 2321a to the second surface 2321b. The pressure relief mechanism 23 is provided with a groove 236, which is recessed from the first surface 2321a along the direction from the first surface 2321a to the second surface 2321b. The second portion 2322, the weak portion 231, and the pressure relief area 235 together enclose at least a portion of the groove 236.

[0179] Wherein, the first surface 2321a and the second surface 2321b are respectively the two sides of the first part 2321 of the connecting portion 232 in the thickness direction X of the wall portion. For example, the first surface 2321a and the second surface 2321b are parallel to each other.

[0180] Optionally, the first surface 2321a may be the surface of the first portion 2321 facing the electrode assembly 22 in the thickness direction X of the wall, or it may be the surface of the first portion 2321 facing away from the electrode assembly 22 in the thickness direction X of the wall. For example, in the embodiment of this application, the first surface 2321a is the surface of the first portion 2321 facing away from the electrode assembly 22 in the thickness direction X of the wall. Correspondingly, the second surface 2321b is the surface of the first portion 2321 facing the electrode assembly 22 in the thickness direction X of the wall, that is, the second surface 2321b is disposed facing the electrode assembly 22 in the thickness direction X of the wall.

[0181] The second part 2322 protrudes from the second surface 2321b along the direction from the first surface 2321a toward the second surface 2321b. That is, in the thickness direction X of the wall, the second part 2322 protrudes from the first part 2321 toward one side of the first part 2321 and protrudes from the second surface 2321b of the first part 2321.

[0182] The pressure relief mechanism 23 is provided with a groove 236. The groove 236 is recessed from the first surface 2321a in the direction from the first surface 2321a to the second surface 2321b. The second part 2322, the weak part 231 and the pressure relief area 235 together enclose and form at least a part of the groove 236. That is, the second part 2322, the weak part 231 and the pressure relief area 235 of the pressure relief mechanism 23 together enclose and form the groove 236 recessed from the first surface 2321a in the direction from the first surface 2321a to the second surface 2321b, so that the groove opening of the groove 236 is a structure formed on the first surface 2321a.

[0183] In this embodiment, the pressure relief mechanism 23 has a groove 236 on one side of the wall thickness direction X. By setting the second part 2322 to protrude from the second surface 2321b of the first part 2321 along the direction from the first surface 2321a to the second surface 2321b in the wall thickness direction X, and the second part 2322, the weak part 231 and the pressure relief area 235 together enclose at least part of the groove 236 of the pressure relief mechanism 23, the battery cell 20 with this structure can reduce the difficulty of bending the second part 2322 to form multiple bent segments 2322a connected in sequence, and can reduce the difficulty of forming the second part 2322 between the first part 2321 and the weak part 231. On the other hand, it can optimize the spatial layout of the second part 2322 in the wall thickness direction X, which helps to alleviate the phenomenon that the second part 2322 occupies the space on both sides of the first part 2321.

[0184] According to some embodiments of this application, referring to Figures 5 and 6, in the cross-section of the connecting portion 232, the angle between the surfaces of two adjacent bent segments 2322a facing the groove 236 is α, which satisfies 90°≤α≤150°.

[0185] Wherein, α is the angle between the inner surface of the groove 236 and the inner surface of the two adjacent and connected bent segments 2322a in the second part 2322 in the cross section perpendicular to the second direction Z.

[0186] For example, α can be 90°, 92°, 95°, 98°, 100°, 102°, 105°, 108°, 110°, 112°, 115°, 118°, 120°, 122°, 125°, 128°, 130°, 132°, 135°, 138°, 140°, 142°, 145°, 148°, or 150°, etc.

[0187] In this embodiment, the angle between the surfaces of two adjacent bending segments 2322a facing the groove 236 is 90 to 150 degrees. On the one hand, setting the angle between the surfaces of two adjacent bending segments 2322a facing the groove 236 to be greater than or equal to 90 degrees can reduce the forming difficulty of bending the second part 2322 to form multiple sequentially connected bending segments 2322a, and can alleviate the phenomenon of large stress concentration at the connection position of two adjacent bending segments 2322a. On the other hand, setting the angle between the surfaces of two adjacent bending segments 2322a facing the groove 236 to be less than or equal to 150 degrees can improve the buffering effect of the second part 2322 between the weak part 231 and the first part 2321, which is beneficial to reduce the stress transmitted from the outer shell 21 to the weak part 231 through the connecting part 232 when it is subjected to impact or expansion, thereby improving the fatigue resistance of the pressure relief mechanism 23 and reducing the risk of fatigue cracking in the weak part 231 of the pressure relief mechanism 23 during use.

[0188] In some embodiments, as shown in Figure 6, 100°≤α≤140°.

[0189] In this embodiment, the angle between the surfaces of two adjacent bending segments 2322a facing the groove 236 is 100 to 140 degrees. On the one hand, setting the angle between the surfaces of two adjacent bending segments 2322a facing the groove 236 to be greater than or equal to 100 degrees can further reduce the forming difficulty of bending the second part 2322 to form a series of connected bending segments 2322a, and can further alleviate the phenomenon of large stress concentration at the connection position of two adjacent bending segments 2322a. On the other hand, setting the angle between the surfaces of two adjacent bending segments 2322a facing the groove 236 to be less than or equal to 140 degrees can further improve the buffering effect of the second part 2322 between the weak part 231 and the first part 2321, which is conducive to further reducing the stress transmitted from the outer shell 21 to the weak part 231 through the connection part 232 when it is subjected to impact or expansion, so as to further improve the fatigue resistance of the pressure relief mechanism 23, thereby further reducing the risk of fatigue cracking of the weak part 231 of the pressure relief mechanism 23 during use.

[0190] According to some embodiments of this application, referring to Figures 5 and 6, a plurality of bending segments 2322a include a first bending segment 2322b connected to the first portion 2321. In the cross-section of the connecting portion 232, the angle between the surface of the first bending segment 2322b facing away from the groove 236 and the second surface 2321b is β, which satisfies 80°≤β≤150°.

[0191] Among them, the first bending segment 2322b is one of the multiple bending segments 2322a of the second part 2322 that is directly connected to the first part 2321.

[0192] β is the angle between the outer surface of the first bent segment 2322b and the outer surface 2321b of the first part 2321 in a cross section perpendicular to the second direction Z.

[0193] For example, β can be 80°, 82°, 85°, 88°, 90°, 92°, 95°, 98°, 100°, 102°, 105°, 108°, 110°, 112°, 115°, 118°, 120°, 122°, 125°, 128°, 130°, 132°, 135°, 138°, 140°, 142°, 145°, 148°, or 150°, etc.

[0194] In this embodiment, the angle between the surface of the first bent segment 2322b facing away from the groove 236 and the second surface 2321b of the first portion 2321 is between 80 and 150 degrees. On the one hand, setting the angle between the surface of the first bent segment 2322b facing away from the groove 236 and the second surface 2321b of the first portion 2321 to be greater than or equal to 80 degrees reduces the connection difficulty between the first portion 2321 and the first bent segment 2322b, thereby reducing the forming difficulty of the connecting part 232, and also alleviates the phenomenon of large stress concentration at the connection position of the first portion 2321 and the first bent segment 2322b. On the other hand… Setting the angle between the surface of the first bending segment 2322b away from the groove 236 and the second surface 2321b of the first part 2321 to less than or equal to 150 degrees can alleviate the phenomenon that the bending angle of the first bending segment 2322b is too large compared to the first part 2321, thereby reducing the space occupied by the connecting part 232 in the thickness direction X of the wall, which is beneficial to optimizing the space utilization of the battery cell 20, and can improve the buffering effect of the second part 2322 between the weak part 231 and the first part 2321, which is beneficial to reducing the stress transmitted to the weak part 231 through the connecting part 232 when the outer shell 21 is subjected to impact or expansion.

[0195] In some embodiments, as shown in Figure 6, 85°≤β≤100°.

[0196] In this embodiment, the angle between the surface of the first bent segment 2322b facing away from the groove 236 and the second surface 2321b of the first part 2321 is 85 degrees to 100 degrees. On the one hand, setting the angle between the surface of the first bent segment 2322b facing away from the groove 236 and the second surface 2321b of the first part 2321 to be greater than or equal to 85 degrees can further reduce the connection difficulty between the first part 2321 and the first bent segment 2322b, thereby further reducing the forming difficulty of the connecting part 232, and can further alleviate the phenomenon of large stress concentration at the connection position of the first part 2321 and the first bent segment 2322b. On the other hand, the angle between the first bent segment 2322b facing away from the groove 236 and the second surface 2321b of the first part 2321 is 85 degrees to 100 degrees. The angle between the surface of the bent segment 2322b away from the groove 236 and the second surface 2321b of the first part 2321 is further set to be less than or equal to 100 degrees, which can further alleviate the phenomenon that the bending angle of the first bent segment 2322b is too large compared to the first part 2321, so as to further reduce the space occupied by the connecting part 232 in the thickness direction X of the wall, which is conducive to optimizing the space utilization of the battery cell 20, and can further improve the buffering effect of the second part 2322 between the weak part 231 and the first part 2321, which is conducive to further reducing the stress transmitted to the weak part 231 through the connecting part 232 when the outer shell 21 is subjected to impact or expansion.

[0197] According to some embodiments of this application, referring to Figures 5 and 6, along the thickness direction X of the wall portion, the second portion 2322 protrudes from the second surface 2321b by a dimension L1, satisfying 0.2mm≤L1≤7mm.

[0198] Wherein, L1 is the end of the second part 2322 that is furthest from the second surface 2321b in the thickness direction X of the wall portion and the minimum distance between the second surface 2321b and the wall portion in the thickness direction X.

[0199] For example, the size L1 of the second portion 2322 protruding from the second surface 2321b can be 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.8mm, 3mm, 3.2mm, 3.5mm, 3.8mm, 4mm, 4.2mm, 4.5mm, 4.8mm, 5mm, 5.2mm, 5.5mm, 5.8mm, 6mm, 6.2mm, 6.5mm, 6.8mm, or 7mm, etc.

[0200] In this embodiment, the second part 2322 protrudes from the second surface 2321b in the thickness direction X of the wall by an amount of 0.2 mm to 7 mm. On the one hand, setting the size of the second part 2322 protruding from the second surface 2321b to be greater than or equal to 0.2 mm can reduce the difficulty of bending the second part 2322 between the first part 2321 and the weak part 231 to form multiple bent segments 2322a, thereby reducing the molding difficulty of the second part 2322 and improving the buffering effect of the second part 2322 between the weak part 231 and the first part 2321. On the other hand, setting the size of the second part 2322 protruding from the second surface 2321b to be less than or equal to 7 mm can reduce the space occupied by the connecting part 232 in the thickness direction X of the wall, which is beneficial to optimizing the space utilization of the battery cell 20.

[0201] In some embodiments, as shown in Figure 6, 0.2mm ≤ L1 ≤ 5mm.

[0202] In this embodiment, by further setting the size of the second part 2322 protruding from the second surface 2321b to less than or equal to 5mm, the space occupied by the connecting part 232 in the thickness direction X of the wall can be further reduced, which is beneficial to further improve the space utilization of the battery cell 20.

[0203] According to some embodiments of this application, as shown in Figures 5, 6 and 7, the pressure relief mechanism 23 is provided with a pressure relief groove 234, the bottom wall of the pressure relief groove 234 forms a weak part 231, and the pressure relief groove 234 is provided on the surface of the pressure relief mechanism 23 facing the groove 236.

[0204] Among them, the bottom wall of the pressure relief groove 234 forms a weak part 231. That is to say, the part of the pressure relief mechanism 23 with the pressure relief groove 234 and the part corresponding to the bottom surface of the pressure relief groove 234 in the thickness direction X of the wall is the weak part 231 of the pressure relief mechanism 23.

[0205] Alternatively, the pressure relief groove 234 can be formed by various methods, such as stamping or cold heading. Taking the stamping method for forming the pressure relief groove 234 as an example, the pressure relief groove 234 can be stamped on the surface of one side of the pressure relief mechanism 23 along the thickness direction X of the wall.

[0206] The pressure relief groove 234 is disposed on the surface of the pressure relief mechanism 23 facing the groove 236. That is, the pressure relief groove 234 is disposed on the groove wall surface of the groove 236, so that the pressure relief groove 234 and the groove 236 are interconnected.

[0207] In this embodiment, a weak portion 231 is formed on the pressure relief mechanism 23 by creating a pressure relief groove 234 on the pressure relief mechanism 23. This allows the pressure relief mechanism 23 to crack along at least a portion of the weak portion 231 when the battery cell 20 is depressurized. This also reduces the difficulty of forming the weak portion 231 on the pressure relief mechanism 23, resulting in a simple structure and ease of manufacturing. Furthermore, by placing the pressure relief groove 234 on the surface of the pressure relief mechanism 23 facing the groove 236, both the pressure relief groove 234 and the groove 236 are located on the same side of the pressure relief mechanism 23 in the thickness direction X of the wall portion. This allows the pressure relief groove 234 to be formed simultaneously with the groove 236, reducing the difficulty of forming the pressure relief groove 234 on the pressure relief mechanism 23 and optimizing the production cycle of the battery cell 20.

[0208] According to some embodiments of this application, the second surface 2321b is disposed facing the electrode assembly 22 along the thickness direction X of the wall portion. That is, the surface of the first portion 2321 facing the electrode assembly 22 in the thickness direction X of the wall portion is the second surface 2321b. Correspondingly, the first surface 2321a is the surface of the first portion 2321 facing away from the electrode assembly 22 in the thickness direction X of the wall portion. In other words, the second portion 2322 has a structure that protrudes and extends from the surface of the first portion 2321 facing the electrode assembly 22 in the thickness direction X of the wall portion.

[0209] In this embodiment, by setting the second surface 2321b of the first part 2321 to face the electrode assembly 22, the second part 2322 of the connecting part 232 protrudes from the first part 2321 and faces the inside of the battery cell 20. This makes the groove 236 formed by the second part 2322, the weak part 231, and the pressure relief area 235 recessed towards the inside of the battery cell 20. The battery cell 20 with this structure can provide a certain degree of protection for the second part 2322 and the weak part 231 connecting the second part 2322, which helps to reduce wear or collision during use or assembly. This can effectively improve the stability and service life of the pressure relief mechanism 23, and alleviate the phenomenon of premature valve opening and pressure relief due to damage to the pressure relief mechanism 23, which is beneficial to improving the reliability and service life of the battery cell 20.

[0210] According to some embodiments of this application, referring to FIG6, the surfaces of two adjacent bent segments 2322a facing the groove 236 are connected by a first rounded corner surface 2323. That is, the inner surfaces of two adjacent and connected bent segments 2322a facing the groove 236 have a rounded corner structure.

[0211] In this embodiment, by setting the surfaces of two adjacent bending segments 2322a facing the groove 236 to be connected by a first rounded corner surface 2323, the connection position of the surfaces of the two adjacent bending segments 2322a facing the groove 236 is a rounded transition structure. The battery cell 20 with this structure can alleviate the scraping or bumping of other components at the connection position of the surfaces of the two adjacent bending segments 2322a facing the groove 236, and can reduce the stress concentration at the connection position of the surfaces of the two adjacent bending segments 2322a facing the groove 236.

[0212] According to some embodiments of this application, as shown in FIG6, the surfaces of two adjacent bent segments 2322a facing away from the groove 236 are connected by a second rounded corner surface 2324. That is, the outer surfaces of two adjacent and connected bent segments 2322a facing away from the groove 236 have a rounded corner structure.

[0213] In this embodiment, by setting the surfaces of two adjacent bending segments 2322a facing away from the groove 236 to be connected by the second rounded corner surface 2324, the connection position of the surfaces of the two adjacent bending segments 2322a facing away from the groove 236 is a rounded transition structure. The battery cell 20 with this structure can alleviate the scraping or bumping of other components at the connection position of the surfaces of the two adjacent bending segments 2322a facing away from the groove 236, and can reduce the stress concentration phenomenon at the connection position of the surfaces of the two adjacent bending segments 2322a facing away from the groove 236.

[0214] According to some embodiments of this application, referring to FIG6, a plurality of bent segments 2322a include a first bent segment 2322b connected to the first portion 2321. The surface of the first bent segment 2322b facing the groove 236 is connected to the first surface 2321a through a third rounded corner surface 2325. That is, the inner surface of the first bent segment 2322b facing the groove 236 and the first surface 2321a have a rounded corner structure.

[0215] In this embodiment, by setting the surface of the first bent segment 2322b facing the groove 236 and the first surface 2321a of the first part 2321 to be connected by the third rounded corner surface 2325, the connection position of the surface of the first bent segment 2322b facing the groove 236 and the first surface 2321a of the first part 2321 is a rounded transition structure. The battery cell 20 with this structure can alleviate the scraping or bumping of other components at the connection position of the surface of the first bent segment 2322b facing the groove 236 and the first surface 2321a of the first part 2321, and can reduce the stress concentration phenomenon at the connection position of the surface of the first bent segment 2322b facing the groove 236 and the first surface 2321a of the first part 2321.

[0216] According to some embodiments of this application, referring to FIG6, a plurality of bent segments 2322a include a first bent segment 2322b connected to the first portion 2321. The surface of the first bent segment 2322b facing away from the groove 236 is connected to the second surface 2321b through a fourth rounded corner surface 2326. That is, the outer surface of the first bent segment 2322b facing away from the groove 236 and the second surface 2321b have a rounded corner structure.

[0217] In this embodiment, by setting the surface of the first bent segment 2322b away from the groove 236 and the second surface 2321b of the first part 2321 to be connected through the fourth rounded corner surface 2326, the connection position between the surface of the first bent segment 2322b away from the groove 236 and the second surface 2321b of the first part 2321 is a rounded transition structure. The battery cell 20 with this structure can alleviate the scraping or bumping of other components at the connection position between the surface of the first bent segment 2322b away from the groove 236 and the second surface 2321b of the first part 2321, and can reduce the stress concentration phenomenon at the connection position between the surface of the first bent segment 2322b away from the groove 236 and the second surface 2321b of the first part 2321.

[0218] According to some embodiments of this application, referring to Figure 6, the wall thickness of the first part 2321 is T1, and the wall thickness of the bent section 2322a is T2, satisfying 0.8≤T2 / T1≤1.1.

[0219] Wherein, the wall thickness T1 of the first part 2321 is the thickness dimension of the first part 2321 in its thickness direction, and the wall thickness T2 of the bent section 2322a is the thickness dimension of the bent section 2322a in its thickness direction.

[0220] It should be noted that the wall thickness of the multiple bending segments 2322a in the second part 2322 all satisfy 0.8≤T2 / T1≤1.1.

[0221] For example, the ratio of the wall thickness T2 of the bent section 2322a to the wall thickness T1 of the first part 2321 can be 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, or 1.1, etc.

[0222] In this embodiment, the ratio of the wall thickness of the bent segment 2322a to the wall thickness of the first part 2321 is 0.8 to 1.1. On the one hand, having a ratio of the wall thickness of the bent segment 2322a to the wall thickness of the first part 2321 greater than or equal to 0.8 can improve the structural strength of the bent segment 2322a, thereby alleviating the deformation or cracking of the bent segment 2322a during use, which is beneficial to improving the stability and reliability of the pressure relief mechanism 23. On the other hand, having a ratio of the wall thickness of the bent segment 2322a to the wall thickness of the first part 2321 less than or equal to 1.1 can alleviate the excessive manufacturing difficulty of bending the second part 2322 to form multiple bent segments 2322a connected in sequence, thereby reducing the forming difficulty of the connecting part 232.

[0223] According to some embodiments of this application, as shown in Figure 6, the wall thickness of the first part 2321 is T1, which satisfies 0.15mm≤T1≤0.5mm.

[0224] For example, the wall thickness T1 of the first part 2321 can be 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, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.42mm, 0.45mm, 0.48mm, 0.49mm, or 0.5mm, etc.

[0225] In this embodiment, on the one hand, by setting the wall thickness of the first part 2321 of the connecting part 232 to be greater than or equal to 0.15mm, the structural strength of the first part 2321 is improved, thereby reducing the occurrence of deformation or cracking of the first part 2321 during use, and improving the connection stability between the first part 2321 and the wall 211, which is beneficial to improving the stability and reliability of the battery cell 20. On the other hand, by setting the wall thickness of the first part 2321 of the connecting part 232 to be less than or equal to 0.5mm, the space occupied by the first part 2321 in the thickness direction X of the wall can be reduced, and the processing difficulty of the connecting part 232 can be reduced.

[0226] In some embodiments, please continue to refer to Figure 6, 0.2mm≤T1≤0.3mm.

[0227] In this embodiment, on the one hand, by further setting the wall thickness of the first part 2321 of the connecting portion 232 to be greater than or equal to 0.2 mm, the structural strength of the first part 2321 is further improved, thereby further reducing the phenomenon of deformation or cracking of the first part 2321 during use, and further improving the connection stability between the first part 2321 and the wall 211, which is conducive to further improving the stability and reliability of the battery cell 20. On the other hand, by further setting the wall thickness of the first part 2321 of the connecting portion 232 to be less than or equal to 0.3 mm, the space occupied by the first part 2321 in the thickness direction X of the wall can be further optimized, and the processing difficulty of the connecting portion 232 can be further reduced.

[0228] According to some embodiments of this application, as shown in FIG6, a plurality of bending segments 2322a include a first bending segment 2322b connected to the first portion 2321 and a second bending segment 2322c connected to the weak portion 231, wherein the wall thickness of the second bending segment 2322c is greater than the wall thickness of the first bending segment 2322b.

[0229] Among them, the first bending segment 2322b is a bending segment 2322a that is directly connected to the first part 2321 among the multiple bending segments 2322a of the second part 2322, and the second bending segment 2322c is a bending segment 2322a that is directly connected to the weak part 231 among the multiple bending segments 2322a of the second part 2322.

[0230] The wall thickness of the second bending segment 2322c is greater than the wall thickness of the first bending segment 2322b. That is, the wall thickness of the bending segment 2322a connected to the first part 2321 among the multiple bending segments 2322a is less than the wall thickness of the bending segment 2322a connected to the weak part 231 among the multiple bending segments 2322a.

[0231] For example, in Figure 6, the second part 2322 includes two bent segments 2322a, which are respectively the first bent segment 2322b and the second bent segment 2322c. If the second part 2322 includes three or more bent segments 2322a, the first bent segment 2322b and the second bent segment 2322c are respectively the two bent segments 2322a located at both ends of the plurality of bent segments 2322a. Correspondingly, the wall thickness of the plurality of bent segments 2322a can be a structure that increases sequentially from the first bent segment 2322b to the second bent segment 2322c.

[0232] In this embodiment, by setting the wall thickness of the second bending segment 2322c, which is used to connect with the weak part 231, to be greater than the wall thickness of the first bending segment 2322b, which is used to connect with the first part 2321, the structural strength of the area where the second part 2322 is connected to the weak part 231 is improved, and the buffering effect of the second part 2322 between the weak part 231 and the first part 2321 is further improved. This helps to further reduce the stress transmitted from the outer shell 21 to the weak part 231 through the connecting part 232 when it is subjected to impact or expansion, thereby further improving the fatigue resistance of the pressure relief mechanism 23 and further reducing the risk of fatigue cracking of the weak part 231 of the pressure relief mechanism 23 during use.

[0233] According to some embodiments of this application, in conjunction with Figures 6 and 7, along the thickness direction X of the wall portion, the minimum thickness of the weak portion 231 is D, which satisfies 0.01mm≤D≤0.2mm.

[0234] Among them, the minimum thickness D of the weak part 231 in the thickness direction X of the wall is the minimum dimension of the weak part 231 in the thickness direction X of the wall. During measurement, the thickness of the weak part 231 at different positions can be measured multiple times and the minimum value can be taken as D.

[0235] For example, the minimum thickness D of the weak portion 231 in the thickness direction X of the wall portion can be 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, or 0.2mm, etc.

[0236] In this embodiment, setting the minimum thickness of the weak portion 231 in the thickness direction X of the wall to be greater than or equal to 0.01 mm can improve the structural strength of the weak portion 231, making it less likely to crack prematurely due to pressure changes inside the battery cell 20 or external impacts. This helps reduce the risk of premature damage to the weak portion 231 and improves the lifespan of the battery cell 20. On the other hand, setting the minimum thickness of the weak portion 231 in the thickness direction X of the wall to be less than or equal to 0.2 mm can reduce the burst pressure required by the pressure relief mechanism 23, allowing the pressure relief mechanism 23 to open and release pressure in a timely manner when the battery cell 20 experiences thermal runaway. This helps improve the timeliness of pressure relief by the pressure relief mechanism 23 and reduces the risk of the battery cell 20 bursting or exploding.

[0237] According to some embodiments of this application, referring to Figures 5, 6, and 7, the area of ​​the orthographic projection of the pressure relief zone 235 in a projection plane perpendicular to the thickness direction X of the wall is S. (100mm) 2 ≤450mm 2 And 0.01mm≤D≤0.16mm; or, 350mm 2 ≤S≤850mm 2 And 0.015mm≤D≤0.17mm; or, 750mm 2 ≤S≤1250mm 2 And 0.02mm≤D≤0.18mm; or, 1150mm 2 ≤S≤1650mm 2 And 0.025mm≤D≤0.19mm; or, 1550mm 2 ≤S≤2100mm 2 And 0.03mm≤D≤0.2mm.

[0238] Where S represents the area of ​​the orthographic projection in the projection plane perpendicular to the thickness direction X of the wall, as shown in Figure 7. In Figure 7, the S of the pressure relief zone 235 is marked with a grid line. It should be noted that the grid line is only for the convenience of displaying S and does not represent any physical meaning.

[0239] The area S of the pressure relief zone 235 projected onto a plane perpendicular to the thickness direction X of the wall can be 100 mm². 2 150mm 2 200mm 2 250mm 2 300mm 2 350mm 2 400mm 2 450mm 2 500mm 2 550mm 2 600mm 2 650mm 2 700mm 2 750mm 2 800mm 2 850mm 2 900mm 2 950mm 2 1000mm 2 1050mm 2 1100mm 2 1150mm 2 1200mm 2 1250mm 21300mm 2 1350mm 2 1400mm 2 1450mm 2 1500mm 2 1550mm 2 1600mm 2 1650mm 2 1700mm 2 1750mm 2 1800mm 2 1850mm 2 1900mm 2 1950mm 2 2000mm 2 2050mm 2 Or 2100mm 2 wait.

[0240] When 100mm 2 ≤S≤450mm 2 In this case, the minimum thickness D of the weak part 231 in the thickness direction X of the wall can be 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, or 0.16mm, etc.

[0241] When 350mm 2 ≤S≤850mm 2 In this case, the minimum thickness D of the weak part 231 in the thickness direction X of the wall can be 0.015mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, or 0.17mm, etc.

[0242] When 750mm 2 ≤S≤1250mm 2 When the weak part 231 has a minimum thickness D in the thickness direction X of the wall, it can be 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, or 0.18mm, etc.

[0243] When 1150mm 2 ≤S≤1650mm 2 When the weak part 231 has a minimum thickness D in the thickness direction X of the wall, it can be 0.025mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, etc.

[0244] When 1550mm 2 ≤S≤2100mm 2 When the weak part 231 has a minimum thickness D in the thickness direction X of the wall, it can be 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, or 0.2mm, etc.

[0245] In this embodiment, when the projected area of ​​the pressure relief zone 235 formed by the weak portion 231 is large, the pressure relief zone 235 is more susceptible to internal pressure, causing the weak portion 231 to crack. Therefore, when the projected area of ​​the pressure relief zone 235 increases, the thickness of the weak portion 231 can be increased to ensure the same burst pressure. For example, when the projected area is 100mm... 2 ≤S≤450mm 2 When D ≥ 0.01 mm, the thickness of the weak part 231 is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 100 mm... 2 ≤S≤450mm 2 When D ≤ 0.16 mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open and relieve pressure in a timely manner when the battery cell 20 experiences thermal runaway, thus improving the timeliness of pressure relief by the pressure relief mechanism 23. Therefore, when 100 mm 2 ≤S≤450mm 2 When 0.01mm≤D≤0.16mm, both the lifespan of the battery cell 20 and the timeliness of pressure relief can be considered. When 350mm... 2 ≤S≤850mm 2When D ≥ 0.015 mm, the thickness of the weak part 231 is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 350 mm... 2 ≤S≤850mm 2 When D ≤ 0.17 mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open and relieve pressure in a timely manner when the battery cell 20 experiences thermal runaway, thus improving the timeliness of pressure relief by the pressure relief mechanism 23. Therefore, when 350 mm 2 ≤S≤850mm 2 When 0.015mm ≤ D ≤ 0.17mm, both the lifespan of the battery cell 20 and the timeliness of pressure relief can be considered. When 750mm... 2 ≤S≤1250mm 2 When D ≥ 0.02 mm, the thickness of the weak part 231 is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 750 mm... 2 ≤S≤1250mm 2 When D≤0.18mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open and relieve pressure in a timely manner when the battery cell 20 experiences thermal runaway, thus improving the timeliness of pressure relief. Therefore, when 750mm 2 ≤S≤1250mm 2 When 0.02mm≤D≤0.18mm, both the lifespan of the battery cell 20 and the timeliness of pressure relief can be considered. When 1150mm... 2 ≤S≤1650mm 2 When D ≥ 0.025 mm, the thickness of the weak part 231 is relatively large, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 1150 mm... 2 ≤S≤1650mm 2 When D≤0.19mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open and relieve pressure in a timely manner when the battery cell 20 experiences thermal runaway, thus improving the timeliness of pressure relief by the pressure relief mechanism 23. Therefore, when 1550mm 2 ≤S≤2100mm 2 When 0.025mm≤D≤0.19mm, both the lifespan of the battery cell 20 and the timeliness of pressure relief can be considered. When 1550mm... 2 ≤S≤2100mm 2When D ≥ 0.03 mm, the thickness of the weak part 231 is relatively large, and the weak part 231 is less likely to crack prematurely due to pressure changes inside the battery cell 20 or external impacts. This helps reduce the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 1550 mm 2 ≤S≤2100mm 2 When D≤0.2mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open and relieve pressure in a timely manner when the battery cell 20 experiences thermal runaway, thus improving the timeliness of pressure relief by the pressure relief mechanism 23. Therefore, when 1550mm 2 ≤S≤2100mm 2 Furthermore, when 0.03mm≤D≤0.2mm, the lifespan of the battery cell 20 and the timeliness of pressure relief can be balanced.

[0246] In some embodiments, please continue to refer to Figures 5, 6 and 7, 100mm 2 ≤S≤450mm 2 And 0.02mm≤D≤0.16mm; or, 350mm 2 ≤S≤850mm 2 And 0.025mm≤D≤0.17mm; or, 750mm 2 ≤S≤1250mm 2 And 0.03mm≤D≤0.18mm; or, 1150mm 2 ≤S≤1650mm 2 And 0.035mm≤D≤0.19mm; or, 1550mm 2 ≤S≤2100mm 2 And 0.04mm≤D≤0.2mm.

[0247] In this embodiment, when 100mm 2 ≤S≤450mm 2 When D ≥ 0.02 mm, the thickness of the weak part 231 is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 100 mm... 2 ≤S≤450mm 2 When D ≤ 0.16 mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 100 mm 2 ≤S≤450mm 2Furthermore, when 0.02mm ≤ D ≤ 0.16mm, it better balances the lifespan of the battery cell 20 and the timeliness of pressure relief. When 350mm... 2 ≤S≤850mm 2 When D ≥ 0.025 mm, the thickness of the weak part 231 is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 350 mm... 2 ≤S≤850mm 2 When D ≤ 0.17 mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 350 mm 2 ≤S≤850mm 2 Furthermore, when 0.025mm ≤ D ≤ 0.17mm, it better balances the lifespan of the battery cell 20 and the timeliness of pressure relief. When 750mm... 2 ≤S≤1250mm 2 When D≥0.03mm, the thickness of the weak part 231 is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 750mm... 2 ≤S≤1250mm 2 When D≤0.18mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 750mm 2 ≤S≤1250mm 2 Furthermore, when 0.03mm ≤ D ≤ 0.18mm, it better balances the lifespan of the battery cell 20 and the timeliness of pressure relief. When 1150mm... 2 ≤S≤1650mm 2 When D ≥ 0.035 mm, the thickness of the weak part 231 is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 1150 mm... 2 ≤S≤1650mm 2 When D≤0.19mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 1550mm 2≤S≤2100mm 2 Furthermore, when 0.035mm ≤ D ≤ 0.19mm, it better balances the lifespan of the battery cell 20 and the timeliness of pressure relief. When 1550mm... 2 ≤S≤2100mm 2 When D≥0.04mm, the thickness of the weak part 231 is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 231 and improves the lifespan of the battery cell 20. When 1550mm... 2 ≤S≤2100mm 2 When D≤0.2mm, the thickness of the weak part 231 will not be too large, allowing the pressure relief mechanism 23 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 1550mm 2 ≤S≤2100mm 2 Furthermore, when 0.04mm≤D≤0.2mm, it is better able to balance the service life of the battery cell 20 and the timeliness of pressure relief.

[0248] According to some embodiments of this application, referring to Figures 5 and 7, and further referring to Figure 8, Figure 8 is a cross-sectional view of the pressure relief mechanism 23 provided in some embodiments of this application, perpendicular to the first direction Y. The weak portion 231 includes a first weak segment 231a and a second weak segment 231b connected end to end. Along the thickness direction X of the wall, the thickness of the second weak segment 231b is greater than the thickness of the first weak segment 231a.

[0249] The weak portion 231 includes a first weak segment 231a and a second weak segment 231b connected end to end. That is, the weak portion 231 of the ring structure is divided into a first weak segment 231a and a second weak segment 231b that are connected to each other. The thickness of the second weak segment 231b is greater than the thickness of the first weak segment 231a. In other words, the thickness of the part of the weak portion 231 located in the second weak segment 231b in the thickness direction X of the wall is greater than the thickness of the part of the weak portion 231 located in the first weak segment 231a in the thickness direction X of the wall.

[0250] In this embodiment, by setting the thickness of the second weak segment 231b of the weak portion 231 in the thickness direction X of the wall portion to be greater than the thickness of the first weak segment 231a of the weak portion 231 in the thickness direction X of the wall portion, the structural strength of the second weak segment 231b is greater than that of the first weak segment 231a. This allows the first weak segment 231a to crack first compared to the second weak segment 231b when the battery cell 20 is depressurized, so that the depressurization area 235 of the depressurization mechanism 23 located inside the weak portion 231 can be flipped around the second weak segment 231b as the axis and open to depressurize. This helps to improve the depressurization smoothness of the depressurization mechanism 23 of the battery cell 20, thereby improving the timeliness of depressurization of the battery cell 20.

[0251] According to some embodiments of this application, referring to FIG8, along the thickness direction X of the wall portion, the difference between the thickness of the second weak segment 231b and the thickness of the first weak segment 231a is greater than or equal to 0.02mm. That is, the thickness of the second weak segment 231b in the thickness direction X of the wall portion is 0.02mm or more greater than the thickness of the first weak segment 231a in the thickness direction X of the wall portion.

[0252] In this embodiment, by setting the thickness of the second weak segment 231b to be greater than or equal to 0.02 mm of the thickness of the first weak segment 231a, the structural strength difference between the second weak segment 231b and the first weak segment 231a is increased. This is beneficial to ensure that after the first weak segment 231a cracks before the second weak segment 231b, the pressure relief area 235 of the pressure relief mechanism 23 located inside the weak part 231 can be flipped around the second weak segment 231b as an axis.

[0253] In some embodiments, referring further to FIG8, along the thickness direction X of the wall portion, the difference between the thickness of the second weak segment 231b and the thickness of the first weak segment 231a is greater than or equal to 0.05 mm. That is, the thickness of the second weak segment 231b in the thickness direction X of the wall portion is 0.05 mm or more greater than the thickness of the first weak segment 231a in the thickness direction X of the wall portion.

[0254] In this embodiment, by further setting the thickness of the second weak segment 231b to be greater than or equal to 0.05mm of the thickness of the first weak segment 231a, the structural strength difference between the second weak segment 231b and the first weak segment 231a is further amplified. This is beneficial to further realize that after the first weak segment 231a cracks before the second weak segment 231b, the pressure relief area 235 of the pressure relief mechanism 23 located inside the weak part 231 can be flipped around the second weak segment 231b as an axis.

[0255] According to some embodiments of this application, referring to Figure 7, the second weak segment 231b extends along a straight trajectory. That is, the second weak segment 231b is a strip structure extending along a straight trajectory.

[0256] For example, the second weak segment 231b is a strip structure extending along the first direction Y.

[0257] In this embodiment, by setting the second weak segment 231b as a structure extending along a straight trajectory, it is beneficial to improve the smoothness of the pressure relief area 235 located inside the weak part 231 of the pressure relief mechanism 23 when it flips around the second weak segment 231b as an axis after the first weak segment 231a cracks. It is also beneficial to expand the flipping angle of the pressure relief area 235 located inside the weak part 231 of the pressure relief mechanism 23, so as to improve the pressure relief smoothness and pressure relief rate of the battery cell 20.

[0258] According to some embodiments of this application, referring to Figures 5, 7, and 8, the weak portion 231 includes two arc segments 2311 and two straight segments 2312. One arc segment 2311, one straight segment 2312, another arc segment 2311, and another straight segment 2312 are connected end-to-end. The two arc segments 2311 are arranged opposite each other along a first direction Y, and extend along an arc trajectory. The two straight segments 2312 are arranged opposite each other along a second direction Z, and extend along the first direction Y. The first direction Y, the second direction Z, and the thickness direction X of the wall are perpendicular to each other. The first weak portion 231a includes two arc segments 2311 and one straight segment 2312, and the second weak portion 231b is another straight segment 2312.

[0259] Among them, the two arc segments 2311 and the two straight segments 2312 of the weak part 231 are arranged alternately and connected to each other along the extension direction of the weak part 231. The two arc segments 2311 and the one straight segment 2312 of the weak part 231 constitute the first weak segment 231a of the weak part 231. Correspondingly, the other straight segment 2312 of the weak part 231 is the second weak segment 231b of the weak part 231.

[0260] It should be noted that in an embodiment where the thickness of the second weak segment 231b is greater than the thickness of the first weak segment 231a along the thickness direction X of the wall, the thickness of the straight segment 2312 of the second weak segment 231b in the thickness direction X of the wall is greater than the thickness of the two curved segments 2311 and the other straight segment 2312 in the thickness direction X of the wall.

[0261] In this embodiment, the first weak segment 231a includes two arc segments 2311 and one straight segment 2312, and the second weak segment 231b is another straight segment 2312 of the weak part 231. The arc segment 2311, the straight segment 2312, the other arc segment 2311, and the other straight segment 2312 are connected end-to-end. This is achieved by configuring the two arc segments 2311 to extend along an arc trajectory and be relatively positioned along the first direction Y, and configuring the two straight segments 2312 to extend along the first direction Y and be relatively positioned along the second direction Z. The structure of the battery cell 20 facilitates the forming of a first weak segment 231a and a second weak segment 231b with different thicknesses on the pressure relief mechanism 23, which helps reduce the processing difficulty of the pressure relief mechanism 23. On the other hand, it can further improve the smoothness of the pressure relief area 235 located inside the weak part 231 of the pressure relief mechanism 23 when it flips around the second weak segment 231b after the first weak segment 231a cracks. It also helps to further expand the flipping angle of the pressure relief area 235 located inside the weak part 231 of the pressure relief mechanism 23, so as to further improve the pressure relief smoothness and pressure relief rate of the battery cell 20.

[0262] According to some embodiments of this application, as shown in Figures 5, 6, 7 and 8, at least a portion of the pressure relief region 235 bulges toward or away from the electrode assembly 22 along the thickness direction X of the wall portion to form a raised portion 233, and a weak portion 231 surrounds the outside of the raised portion 233.

[0263] The raised portion 233 is a raised structure in which at least a portion of the pressure relief region 235 rises toward or away from the electrode assembly 22 in the thickness direction X of the wall. Optionally, the pressure relief region 235 can be a structure in which the raised portion 233 is formed by partial bulging, or it can be a structure in which the raised portion 233 is formed by overall bulging. For example, in FIG5, the pressure relief region 235 is a structure in which the entire raised portion 235 is raised. Correspondingly, the pressure relief region 235 is raised portion 233. Correspondingly, the weak portion 231 directly connects the raised portion 233 and the second portion 2322 of the connecting portion 232.

[0264] The weak portion 231 surrounds the outside of the raised portion 233, that is, the raised portion 233 is located in the area enclosed by the weak portion 231.

[0265] For example, the raised portion 233 is a raised structure that rises in the thickness direction X of the wall portion along the direction from the second surface 2321b to the first surface 2321a. In an embodiment where the second surface 2321b is provided facing the electrode assembly 22, the raised portion 233 is a raised structure that rises in the thickness direction X of the wall portion in a direction away from the electrode assembly 22.

[0266] In this embodiment, by providing a raised portion 233 on the pressure relief area 235 inside the weak portion 231, which protrudes towards or away from the electrode assembly 22, and the weak portion 231 surrounds the outside of the raised portion 233, the battery cell 20 with this structure can, on the one hand, reduce the difficulty of forming the weak portion 231 on the pressure relief mechanism 23, and improve the material flow pattern of the weak portion 231 during the processing, thereby improving the processing consistency of the weak portion 231. On the other hand, it can improve the structural strength of the pressure relief area 235 inside the weak portion 231. This helps to alleviate the deformation and damage of the pressure relief area 235 inside the weak part 231 during use, and also makes the raised part 233 inside the weak part 231 form a pre-deformed structure, so that the weak part 231 of the pressure relief mechanism 23 can crack and relieve pressure. Thus, under the same burst pressure, the thickness of the weak part 231 can be increased to alleviate fatigue cracking of the weak part 231 during use, thereby effectively reducing the risk of premature valve opening of the pressure relief mechanism 23, and improving the service life and reliability of the battery cell 20.

[0267] According to some embodiments of this application, as shown in Figures 5, 6, and 7, at least a portion of the boundary of the raised portion 233 is adjacent to the boundary of the weak portion 231. That is, at least a portion of the raised portion 233 and the weak portion 231 are directly connected.

[0268] In this embodiment, by having at least a portion of the boundary of the raised portion 233 adjacent to the boundary of the weak portion 231, the raised portion 233 can directly pull the weak portion 231 through the adjacent portion when the battery cell 20 is depressurized. This results in a greater shear force on the portion of the weak portion 231 adjacent to the boundary of the raised portion 233, which facilitates the cracking and depressurization of the weak portion 231. Under the same burst pressure, the thickness of the weak portion 231 can be increased to alleviate fatigue cracking and other phenomena that occur in the weak portion 231 during use. This effectively reduces the risk of premature valve opening of the depressurization mechanism 23, thereby improving the service life and reliability of the battery cell 20.

[0269] In some embodiments, please continue to refer to Figures 5, 6, and 7, the boundary of the raised portion 233 is completely adjacent to the boundary of the weak portion 231. That is, the weak portion 231 is a structure that surrounds the raised portion 233 and is directly connected to the raised portion 233. Correspondingly, the pressure relief area 235 formed by the weak portion 231 is the entire raised portion 233. That is, the pressure relief area 235 is a structure that is raised in the thickness direction X of the wall portion in a direction away from or close to the electrode assembly 22 to form the raised portion 233.

[0270] In this embodiment, by setting the boundary of the raised portion 233 to be completely adjacent to the boundary of the weak portion 231, the raised portion 233 can directly pull the weak portion 231 when the battery cell 20 is depressurized, thereby further increasing the shear force on the weak portion 231, which facilitates the cracking and depressurization of the weak portion 231. Under the same burst pressure, the thickness of the weak portion 231 can be further increased to further alleviate fatigue cracking and other phenomena in the weak portion 231 during use. This further reduces the risk of premature valve opening of the depressurization mechanism 23, thereby further improving the service life and reliability of the battery cell 20.

[0271] According to some embodiments of this application, referring to Figures 5 and 6, the first portion 2321 has opposing first surfaces 2321a and second surfaces 2321b in the thickness direction X of the wall portion. The second portion 2322 protrudes from and out of the second surface 2321b along the direction from the first surface 2321a to the second surface 2321b. The pressure relief mechanism 23 is provided with a groove 236, which is recessed from the first surface 2321a in the direction from the first surface 2321a to the second surface 2321b. The second portion 2322, the weak portion 231, and the pressure relief area 235 together enclose at least a portion of the groove 236. In the thickness direction X of the wall portion, the raised portion 233 protrudes along the direction from the second surface 2321b to the first surface 2321a.

[0272] In the thickness direction X of the wall portion, the raised portion 233 protrudes in the direction from the second surface 2321b to the first surface 2321a. That is, in the thickness direction X of the wall portion, the protrusion direction of the raised portion 233 is opposite to the protrusion direction of the second portion 2322. In other words, the raised portion 233 is a structure that protrudes in the thickness direction X of the wall portion toward the interior of the groove 236.

[0273] In this embodiment, the pressure relief mechanism 23 is provided with a groove 236 recessed from the first surface 2321a in the direction from the first surface 2321a to the second surface 2321b. The second part 2322, the weak part 231, and the pressure relief area 235 together enclose at least a portion of the groove 236, and the raised part 233 is a structure that protrudes in the direction from the second surface 2321b to the first surface 2321a. The battery cell 20 with this structure can achieve a different protrusion direction for the raised part 233 and the second part 2322, which is beneficial to improve the pressure relief mechanism 2321. The overall structural strength of 3 is improved to reduce the risk of fatigue cracking or damage to the pressure relief mechanism 23 during use. It also enables the raised portion 233 and the second part 2322 to share a portion of the space in the thickness direction X of the wall, which helps to save the space occupied by the pressure relief mechanism 23 and improve the space utilization of the battery cell 20. On the other hand, it enables the raised portion 233 to be a structure that bulges towards the groove 236. Thus, the groove 236 can also play a certain protective role for the raised portion 233, so as to reduce wear or bumps of the raised portion 233 during use or assembly.

[0274] In some embodiments, referring to FIG5, in the thickness direction X of the wall portion, the raised portion 233 does not extend beyond the first surface 2321a in the direction from the second surface 2321b to the first surface 2321a. That is, the raised portion 233 does not extend beyond the groove of the groove 236 in the thickness direction X of the wall portion.

[0275] In this embodiment, by setting the first protrusion to not extend beyond the first surface 2321a in the direction from the second surface 2321b to the first surface 2321a, it is beneficial to further improve the protection effect of the protrusion 233, so as to further reduce the wear or bumps of the protrusion 233 during use or assembly, thereby improving the reliability and service life of the pressure relief mechanism 23.

[0276] According to some embodiments of this application, referring to FIG5, the raised portion 233 includes a first region 2331 and two second regions 2332. The two second regions 2332 are arranged at intervals along the first direction Y and are respectively connected to the two ends of the first region 2331. The outer surface of the raised portion 233 has a recessed region 2331a. The recessed direction of the recessed region 2331a is opposite to the raised direction of the raised portion 233, and the recessed region 2331a is located within the first region 2331. The first direction Y is perpendicular to the thickness direction X of the wall portion.

[0277] The raised portion 233 includes a first region 2331 and two second regions 2332. The two second regions 2332 are arranged at intervals along the first direction Y and are respectively connected to the two ends of the first region 2331. That is, one second region 2332, the first region 2331 and the other second region 2332 of the raised portion 233 are arranged sequentially and connected along the first direction Y, so that the two second regions 2332 are respectively located at the two ends of the first region 2331 in the second direction Z, and the first region 2331 is connected between the two second regions 2332 in the first direction Y.

[0278] Optionally, the weak portion 231 includes two arc segments 2311 and two straight segments 2312. The arc segment 2311, the straight segment 2312, the other arc segment 2311 and the other straight segment 2312 are connected end to end to form a ring structure of the weak portion 231. The two arc segments 2311 are arranged opposite each other along the first direction Y and are arc-shaped structures extending along the arc trajectory. The two straight segments 2312 are arranged opposite each other along the second direction Z and are strip-shaped structures extending along the first direction Y. Correspondingly, the areas where the raised portion 233 is connected to the two arc segments 2311 are two second areas 2332, and the area where the raised portion 233 is connected to the two straight segments 2312 is a first area 2331.

[0279] For example, both arc segments 2311 are arc-shaped structures extending along a circular arc trajectory.

[0280] The outer surface of the raised portion 233 is recessed to form a recessed area 2331a. The recessed direction of the recessed area 2331a is opposite to the raised direction of the raised portion 233, and the recessed area 2331a is located within the first region 2331. That is to say, the portion of the outer surface of the raised portion 233 located within the first region 2331 is recessed in the opposite direction to the raised direction of the raised portion 233 to form the recessed area 2331a.

[0281] It should be noted that the outer surface and the inner surface of the raised portion 233 are the two sides of the raised portion 233 in the thickness direction X of the wall portion. In the thickness direction X of the wall portion, the direction from the inner surface of the raised portion 233 to the outer surface of the raised portion 233 is the raised direction of the raised portion 233. For example, if the raised portion 233 is a raised structure that rises away from the electrode assembly 22 in the thickness direction X of the wall portion, then the surface of the raised portion 233 on the side of the raised portion 233 that is away from the electrode assembly 22 in the thickness direction X of the wall portion is the outer surface of the raised portion 233; if the raised portion 233 is a raised structure that rises towards the electrode assembly 22 in the thickness direction X of the wall portion, then the surface of the raised portion 233 on the side of the raised portion 233 that faces the electrode assembly 22 in the thickness direction X of the wall portion is the outer surface of the raised portion 233.

[0282] For example, the raised portion 233 is a raised structure that rises in the thickness direction X of the wall portion in a direction away from the electrode assembly 22. Correspondingly, the recessed area 2331a is a structure in which the outer surface of the raised portion 233 is recessed in the thickness direction X of the wall portion in a direction closer to the electrode assembly 22. Of course, in other embodiments, the raised portion 233 can also be a raised structure that rises in the thickness direction X of the wall portion in a direction closer to the electrode assembly 22. Correspondingly, the recessed area 2331a is a structure in which the outer surface of the raised portion 233 is recessed in the thickness direction X of the wall portion in a direction away from the electrode assembly 22.

[0283] In this embodiment, the raised portion 233 includes two second regions 2332 arranged along the first direction Y and a first region 2331 connected between the two second regions 2332. A recessed region 2331a is formed on the outer surface of the raised portion 233, which is recessed in the opposite direction to the raised direction of the raised portion 233. The recessed region 2331a is located within the first region 2331, so that the pressure relief region 235 of the pressure relief mechanism 23 located inside the weak portion 231 has a structure that is both concave and convex. This can improve the structural strength and fatigue resistance of the pressure relief region 235 of the pressure relief mechanism 23 located inside the weak portion 231, thereby improving the overall structural strength of the pressure relief mechanism 23. When the outer shell 21 is subjected to impact or expansion, the strain and strain amplitude of the pressure relief mechanism 23 can be further reduced, thereby further reducing the risk of fatigue cracking in the weak portion 231 of the pressure relief mechanism 23 during use. This can further alleviate the phenomenon of premature valve opening and pressure relief in the pressure relief mechanism 23, which is beneficial to further improve the reliability and service life of the battery cell 20.

[0284] According to some embodiments of this application, as shown in Figures 5 and 6, the raised portion 233 protrudes in the direction away from the electrode assembly 22 along the thickness direction X of the wall portion, and correspondingly, the recessed area 2331a formed on the outer surface of the raised portion 233 is a structure that is recessed in the direction closer to the electrode assembly 22 in the thickness direction X of the wall portion.

[0285] Of course, in other embodiments, the raised portion 233 may also be a structure that protrudes in the thickness direction X of the wall portion toward the electrode assembly 22. Correspondingly, the recessed area 2331a formed on the outer surface of the raised portion 233 is a structure that is recessed in the thickness direction X of the wall portion toward the direction away from the electrode assembly 22.

[0286] In this embodiment, by setting the raised portion 233 to a structure that protrudes in the thickness direction X of the wall portion in a direction away from the electrode assembly 22, on the one hand, the phenomenon that the raised portion 233 occupies the internal space of the battery cell 20 can be reduced, thereby increasing the internal space of the battery cell 20 for accommodating the electrode assembly 22, which is beneficial to improving the energy density of the battery cell 20. On the other hand, the interference phenomenon between the raised portion 233 and other components inside the battery cell 20 can be reduced, which is beneficial to improving the reliability of the battery cell 20.

[0287] According to some embodiments of this application, referring to Figures 5, 6, 7, and 8, the weak portion 231 includes two arc segments 2311 and two straight segments 2312. One arc segment 2311, one straight segment 2312, another arc segment 2311, and another straight segment 2312 are connected end-to-end. The two arc segments 2311 are arranged opposite each other along a first direction Y, and extend along an arc trajectory. The two straight segments 2312 are arranged opposite each other along a second direction Z, and extend along the first direction Y. The first direction Y, the second direction Z, and the thickness direction X of the wall are perpendicular to each other. The areas where the raised portion 233 connects to the two arc segments 2311 are two second regions 2332, and the area where the raised portion 233 connects to the two straight segments 2312 is a first region 2331.

[0288] The weak part 231 includes two arc segments 2311 and two straight segments 2312. One arc segment 2311, one straight segment 2312, another arc segment 2311 and another straight segment 2312 are connected end to end. That is to say, the weak part 231 of the ring structure is composed of two arc segments 2311 and two straight segments 2312, and the two arc segments 2311 and two straight segments 2312 are arranged alternately and connected to each other along the extension direction of the weak part 231.

[0289] It should be noted that the arc segment 2311 of the weak part 231 is a structure that extends along an arc trajectory, and correspondingly, the straight segment 2312 of the weak part 231 is a structure that extends along a straight trajectory. For example, in Figure 7, the arc segment 2311 is a structure that extends along an arc trajectory, and the straight segment 2312 is a structure that extends along the first direction Y. The arc segment 2311 is connected to two straight segments 2312 at both ends in its extension direction, and in the projection plane perpendicular to the thickness direction X of the wall, the orthographic projections of the two arc segments 2311 are arranged axially symmetrically with respect to a straight line extending along the second direction Z.

[0290] The areas where the raised portion 233 is connected to the two arc segments 2311 are the two second regions 2332, and the area where the raised portion 233 is connected to the two straight segments 2312 is the first region 2331. That is to say, in the projection plane perpendicular to the thickness direction X of the wall, the area enclosed by the straight line formed by the line connecting the two endpoints of the arc segment 2311 and the straight line segment 2312 and the arc segment 2311 is the orthographic projection of the second region 2332 of the raised portion 233, and the area enclosed by the straight line formed by the line connecting the two endpoints of the arc segment 2311 and the straight line segment 2312 and the straight line segment 2312 is the orthographic projection of the first region 2331 of the raised portion 233.

[0291] In this embodiment, the weak portion 231 is configured to include two arc segments 2311 arranged opposite each other along the first direction Y and two straight segments 2312 arranged opposite each other along the second direction Z, with each end of the straight segment 2312 connected to one end of the two arc segments 2311, to form a ring-shaped weak portion 231. The areas where the raised portion 233 is connected to the two arc segments 2311 are the two second regions 2332 of the raised portion 233, and the area where the raised portion 233 is connected to the two straight segments 2312 is the first region 2331 of the raised portion 233, to form a first region 2331 connected between the two second regions 2332 in the first direction Y. The pressure relief mechanism 23 with this structure is convenient to form a recessed area 2331a on the first region 2331 of the raised portion 233 that is opposite to the raised direction of the raised portion 233, which helps to reduce the molding difficulty of the pressure relief mechanism 23.

[0292] In some embodiments, referring to FIG7, in a projection plane perpendicular to the thickness direction X of the wall, the orthographic projection of the first region 2331 is rectangular, and the orthographic projection of the second region 2332 is semi-circular. That is, the arc segment 2311 connected to the second region 2332 is a structure extending along an arc trajectory, and the two straight segments 2312 connected to the first region 2331 are parallel to each other, and the straight segments 2312 are tangent to the arc segment 2311.

[0293] In this embodiment, by setting the projection of the first region 2331 on the thickness direction X of the wall to a rectangular structure and setting the projection of the second region 2332 on the thickness direction X of the wall to a semi-circular structure, the raised portion 233 forms the first region 2331 between the two second regions 2332, and the regularity of the shape of the raised portion 233 can be further improved, thereby further reducing the difficulty of forming the recessed area 2331a on the first region 2331, and further reducing the molding difficulty of the pressure relief mechanism 23.

[0294] According to some embodiments of this application, referring to FIG5, along the thickness direction X of the wall, the maximum recess depth of the recessed area 2331a is H, which satisfies 0.05mm≤H≤1mm.

[0295] Among them, the maximum depression depth H of the depression region 2331a in the thickness direction X of the wall is the distance between the lowest point of the depression region 2331a in the thickness direction X of the wall and the highest point of the second region 2332 in the thickness direction X of the wall.

[0296] For example, the maximum recess depth H of the recessed area 2331a in the thickness direction X of the wall portion can be 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, or 0. 42mm, 0.45mm, 0.48mm, 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 or 1mm, etc.

[0297] In this embodiment, on the one hand, setting the maximum recessed depth of the recessed area 2331a in the thickness direction X of the wall portion to be greater than or equal to 0.05 mm can enhance the strengthening effect of the recessed area 2331a on the structural strength of the raised portion 233, thereby improving the structural strength and fatigue resistance of the pressure relief area 235 located inside the weak portion 231 of the pressure relief mechanism 23, which is beneficial to improving the overall structural strength of the pressure relief mechanism 23. On the other hand, setting the maximum recessed depth of the recessed area 2331a in the thickness direction X of the wall portion to be less than or equal to 1 mm can reduce the difficulty of forming the recessed area 2331a on the first region 2331 of the raised portion 233, thereby reducing the manufacturing difficulty of the pressure relief mechanism 23.

[0298] In some embodiments, please continue to refer to Figure 5, 0.1mm≤H≤0.5mm.

[0299] In this embodiment, on the one hand, setting the maximum recessed depth of the recessed area 2331a in the thickness direction X of the wall portion to be greater than or equal to 0.1 mm can further enhance the strengthening effect of the recessed area 2331a on the structural strength of the raised portion 233, thereby further improving the structural strength and fatigue resistance of the pressure relief area 235 located inside the weak portion 231 of the pressure relief mechanism 23, which is conducive to further improving the overall structural strength of the pressure relief mechanism 23. On the other hand, setting the maximum recessed depth of the recessed area 2331a in the thickness direction X of the wall portion to be less than or equal to 0.5 mm can further reduce the difficulty of forming the recessed area 2331a on the first region 2331 of the raised portion 233, thereby further reducing the manufacturing difficulty of the pressure relief mechanism 23.

[0300] According to some embodiments of this application, referring to FIG5, the maximum dimension of the second region 2332 in the thickness direction X of the wall is L2, which satisfies 0.5mm≤L2≤3mm.

[0301] Wherein, the maximum dimension L2 of the second region 2332 in the thickness direction X of the wall is the distance between the end of the second region 2332 closest to the electrode assembly 22 and the end of the second region 2332 furthest from the electrode assembly 22 in the thickness direction X of the wall.

[0302] For example, the maximum dimension L2 of the second region 2332 in the thickness direction X of the wall can be 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, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, or 3mm, etc.

[0303] In this embodiment, on the one hand, by setting the maximum dimension of the second region 2332 of the raised portion 233 in the thickness direction X of the wall to be greater than or equal to 0.5 mm, the strengthening effect of the raised portion 233 on the structural strength of the pressure relief mechanism 23 can be improved, thereby improving the structural strength and fatigue resistance of the pressure relief area 235 located inside the weak portion 231 of the pressure relief mechanism 23. This is beneficial to improving the overall structural strength of the pressure relief mechanism 23 and facilitates the formation of the weak portion 231 on the outside of the raised portion 233, which is beneficial to improving the material flow pattern of the weak portion 231 during the processing, thereby improving the processing consistency of the weak portion 231. On the other hand, setting the maximum dimension of the second region 2332 of the raised portion 233 in the thickness direction X of the wall to be less than or equal to 3 mm can reduce the difficulty of forming the raised portion 233 on the pressure relief area 235 inside the weak portion 231, thereby reducing the manufacturing difficulty of the pressure relief mechanism 23 and mitigating the risk of breakage or cracking of the raised portion 233 during the forming process, thereby improving the processing quality of the pressure relief mechanism 23.

[0304] In some embodiments, please continue to refer to Figure 5, 0.7mm≤L2≤1.6mm.

[0305] In this embodiment, by further setting the maximum dimension of the second region 2332 of the raised portion 233 in the thickness direction X of the wall portion to be greater than or equal to 0.7 mm, the strengthening effect of the raised portion 233 on the structural strength of the pressure relief mechanism 23 can be further improved. This further enhances the structural strength and fatigue resistance of the pressure relief area 235 located inside the weak portion 231 of the pressure relief mechanism 23, which is beneficial to further improving the overall structural strength of the pressure relief mechanism 23. Furthermore, it can further reduce the difficulty of forming the weak portion 231 on the outer side of the raised portion 233, which is beneficial to further improving the thin-walled structure. The material flow pattern of the weak part 231 during the processing is adjusted to further improve the processing consistency of the weak part 231. On the other hand, setting the maximum size of the second region 2332 of the raised part 233 in the thickness direction X of the wall to less than or equal to 1.6 mm can further reduce the difficulty of forming the raised part 233 on the pressure relief area 235 inside the weak part 231, thereby further reducing the manufacturing difficulty of the pressure relief mechanism 23 and further mitigating the risk of breakage or cracking of the raised part 233 during the forming process, thereby further improving the processing quality of the pressure relief mechanism 23.

[0306] According to some embodiments of this application, as shown in Figures 5, 6 and 7, the pressure relief mechanism 23 is provided with a pressure relief groove 234, and the bottom wall of the pressure relief groove 234 forms a weak part 231.

[0307] The pressure relief groove 234 can be provided on the surface of the pressure relief mechanism 23 in the thickness direction X of the wall facing the electrode assembly 22, or it can be provided on the surface of the pressure relief mechanism 23 in the thickness direction X of the wall away from the electrode assembly 22, or the pressure relief groove 234 can be provided on both sides of the pressure relief mechanism 23 in the thickness direction X of the wall, and the pressure relief grooves 234 on both sides of the pressure relief mechanism 23 are arranged opposite to each other in the thickness direction X of the wall, so that the weak part 231 is the part of the pressure relief mechanism 23 located between the bottom surfaces of the two pressure relief grooves 234.

[0308] For example, in this embodiment of the application, the pressure relief groove 234 is disposed on the surface of the pressure relief mechanism 23 on the side away from the electrode assembly 22 in the thickness direction X of the wall.

[0309] In this embodiment, a weak part 231 is formed on the pressure relief mechanism 23 by opening a pressure relief groove 234 on the pressure relief mechanism 23, so that the pressure relief mechanism 23 can crack along at least a part of the weak part 231 when the battery cell 20 is depressurized. This reduces the difficulty of forming the weak part 231 on the pressure relief mechanism 23, and the structure is simple and easy to manufacture.

[0310] According to some embodiments of this application, as shown in FIG4, the pressure relief mechanism 23 and the wall portion 211 are separately disposed. That is, the pressure relief mechanism 23 and the wall portion 211 of the outer casing 21 are two independent components. Correspondingly, the wall portion 211 is provided with a pressure relief hole, and the connecting portion 232 of the pressure relief mechanism 23 is connected to the wall portion 211 and the pressure relief mechanism 23 blocks the pressure relief hole.

[0311] In one embodiment where the connecting portion 232 of the pressure relief mechanism 23 includes a first portion 2321 and a second portion 2322, the first portion 2321 of the connecting portion 232 is connected to the wall portion 211.

[0312] Optionally, the structure by which the first part 2321 of the connecting part 232 is connected to the wall 211 of the housing 21 can be varied, such as welding, snap-fitting, or bonding.

[0313] In this embodiment, by setting the pressure relief mechanism 23 and the wall portion 211 as separate components, it is possible to first process the weak portion 231 and the connecting portion 232 on the pressure relief mechanism 23, and then bend the second part 2322 of the connecting portion 232 into multiple bent segments 2322a connected in sequence before assembling the pressure relief mechanism 23 onto the wall portion 211 of the outer casing 21. This helps to reduce the molding difficulty of the pressure relief mechanism 23 and optimize the production cycle of the battery cell 20.

[0314] In some embodiments, the pressure relief mechanism 23 is welded to the wall portion 211.

[0315] In one embodiment where the connecting portion 232 of the pressure relief mechanism 23 includes a first part 2321 and a second part 2322, the first part 2321 of the connecting portion 232 is welded to the wall portion 211, for example, by laser welding.

[0316] In this embodiment, by connecting the pressure relief mechanism 23 to the wall portion 211 using a welded connection structure, the difficulty of assembling the pressure relief mechanism 23 on the outer casing 21 can be reduced, thereby reducing the manufacturing difficulty of the battery cell 20. On the other hand, the structural strength of the pressure relief mechanism 23 connected to the wall portion 211 can be improved, which is conducive to improving the assembly reliability between the pressure relief mechanism 23 and the wall portion 211, and can also improve the sealing between the pressure relief mechanism 23 and the wall portion 211, which is conducive to improving the stability and reliability of the battery cell 20 in use.

[0317] In some embodiments, the substrate of the pressure relief mechanism 23 is the same as the substrate of the wall portion 211. That is, the material with the largest mass percentage in the material of the pressure relief mechanism 23 is the same as the material with the largest mass percentage in the material of the wall portion 211. For example, the substrate of the pressure relief mechanism 23 and the substrate of the wall portion 211 are both iron.

[0318] In this embodiment, by setting the substrate of the pressure relief mechanism 23 and the substrate of the wall portion 211 to the same structure, it is beneficial to realize that the pressure relief mechanism 23 and the wall portion 211 are welded to the same material. On the one hand, it can reduce the welding difficulty between the pressure relief mechanism 23 and the wall portion 211, thereby improving the assembly efficiency of the battery cell 20. On the other hand, it can alleviate the phenomenon of false welding or welding cracks when the pressure relief mechanism 23 and the wall portion 211 are welded together, which is beneficial to improve the welding quality between the pressure relief mechanism 23 and the wall portion 211, thereby reducing the risk of leakage of the battery cell 20 during use.

[0319] Of course, the structure of the battery cell 20 is not limited to this. In some embodiments, the battery cell 20 can also have other structures. For example, the pressure relief mechanism 23 is integrally formed with the wall portion 211, that is, the pressure relief mechanism 23 and the wall portion 211 are an integral structure. Correspondingly, the weak part 231, the connecting part 232 and the raised part 233 are structures formed on the wall portion 211 by an integral forming process, such as stamping.

[0320] In this embodiment, by setting the pressure relief mechanism 23 and the wall portion 211 as an integral structure, the battery cell 20 with this structure can improve the structural strength of the pressure relief mechanism 23 connected to the wall portion 211, thereby reducing the risk of the pressure relief mechanism 23 falling off during use, and thus improving the stability and reliability of the battery cell 20.

[0321] According to some embodiments of this application, referring to Figure 5, the base material of the pressure relief mechanism 23 is iron. That is, iron is the material with the largest mass percentage in the pressure relief mechanism 23. For example, the material of the pressure relief mechanism 23 can be carbon steel or stainless steel.

[0322] In this embodiment, by setting the base material of the pressure relief mechanism 23 as iron, the structural strength of the pressure relief mechanism 23 can be improved while the material cost of the pressure relief mechanism 23 can be reduced. This not only improves the stability of the pressure relief mechanism 23 in use, but also reduces the manufacturing cost of the pressure relief mechanism 23.

[0323] In some embodiments, the material of the pressure relief mechanism 23 includes at least one of stainless steel and carbon steel.

[0324] The material of the pressure relief mechanism 23 can be carbon steel or stainless steel, and the carbon steel can be low carbon steel, medium carbon steel or high carbon steel.

[0325] In this embodiment, stainless steel and carbon steel have high strength, which can effectively improve the structural strength of the pressure relief mechanism 23, reduce the risk of deformation of the pressure relief mechanism 23 under stress, and help reduce the risk of premature valve opening and pressure relief of the pressure relief mechanism 23, thereby improving the service life and reliability of the battery cell 20.

[0326] In some embodiments, the material of the pressure relief mechanism 23 includes at least one of SUS304, SUS305, SUS316 or SUS316L.

[0327] In this embodiment, SUS304, SUS305, SUS316 or SUS316L have advantages such as corrosion resistance, high temperature resistance and good processing performance. The pressure relief mechanism 23 made of SUS304, SUS305, SUS316 or SUS316L has high strength, which can reduce the risk of deformation of the pressure relief mechanism 23 under stress. This is beneficial to further reduce the risk of premature valve opening and pressure relief of the pressure relief mechanism 23, so as to further improve the service life and reliability of the battery cell 20.

[0328] According to some embodiments of this application, as shown in Figures 3 and 4, the substrate of the wall portion 211 is iron. That is, iron is the material with the largest mass percentage in the wall portion 211. For example, the material of the wall portion 211 can be carbon steel or stainless steel.

[0329] In this embodiment, by setting the base material of the wall portion 211 as iron, the structural strength of the wall portion 211 can be improved while the material cost of the wall portion 211 can be reduced. This not only improves the stability of the wall portion 211 of the outer shell 21, but also reduces the manufacturing cost of the outer shell 21.

[0330] In some embodiments, the material of the wall portion 211 includes at least one of stainless steel and carbon steel.

[0331] The material of the wall 211 can be carbon steel or stainless steel, and the carbon steel can be low carbon steel, medium carbon steel or high carbon steel.

[0332] It should be noted that the material of the wall portion 211 includes at least one of stainless steel and carbon steel. If the wall portion 211 is the end cap 213 of the outer shell 21, the material of the end cap 213 includes at least one of stainless steel and carbon steel. If the wall portion 211 is a wall in the shell 212, the material of the shell 212 includes at least one of stainless steel and carbon steel.

[0333] In this embodiment, stainless steel and carbon steel have high strength, which can effectively improve the structural strength of the wall 211, reduce the risk of deformation of the wall 211 under stress, and optimize the thickness of the wall 211 with the same structural strength, thereby increasing the internal space of the outer shell 21. This allows for more space within the outer shell 21 to accommodate the electrode assembly 22, thereby increasing the energy density of the battery cell 20.

[0334] In some embodiments, the material of the wall portion 211 includes at least one of SUS304, SUS305, SUS316, or SUS316L.

[0335] In this embodiment, SUS304, SUS305, SUS316, or SUS316L have advantages such as corrosion resistance, high temperature resistance, and good processing performance. The wall portion 211 made of SUS304, SUS305, SUS316, or SUS316L has high strength, thereby reducing the risk of deformation of the wall portion 211 under stress. Furthermore, the thickness of the wall portion 211 can be further optimized under the same structural strength, so as to further increase the internal space of the outer shell 21. Thus, in the same volume of the outer shell 21, the space inside the outer shell 21 for accommodating the electrode assembly 22 can be further increased, thereby further improving the energy density of the battery cell 20.

[0336] According to some embodiments of this application, as shown in Figures 3 and 4, the outer casing 21 may include a housing 212 and an end cap 213. The housing 212 includes an integrally formed side wall and a bottom wall. The side wall surrounds the bottom wall. Along the thickness direction X of the wall portion, one end of the side wall is connected to the bottom wall, and the other end forms an opening 2121. The side wall and the bottom wall together define a receiving cavity. The electrode assembly 22 is received in the receiving cavity. The end cap 213 closes the opening 2121. The bottom wall is a wall portion 211.

[0337] The shell 212 includes an integrally formed side wall and bottom wall. In other words, the shell 212 is manufactured using an integral forming process, such as stamping, casting or extrusion molding. Thus, the side wall and bottom wall of the shell 212 are an integral structure.

[0338] The bottom wall is the wall portion 211, that is, the wall portion 211 is the bottom wall of the housing 212 that is opposite to the end cap 213 in the thickness direction X of the wall portion, that is, the pressure relief mechanism 23 is provided on the bottom wall of the housing 212.

[0339] In this embodiment, by setting the wall portion 211 of the outer casing 21 as the bottom wall of the casing 212 opposite to the end cap 213 in the thickness direction X of the wall portion, the battery cell 20 with this structure can ensure that the area of ​​the outer casing 21 where the pressure relief mechanism 23 is provided is far away from the end cap 213. This can effectively alleviate the stress generated by the connection between the end cap 213 and the casing 212 on the pressure relief mechanism 23, thereby reducing the impact on the pressure relief mechanism 23. This helps to reduce the risk of cracking or structural strength reduction of the weak part 231 of the pressure relief mechanism 23 under the stress, thereby improving the service life and reliability of the battery cell 20.

[0340] It should be noted that the structure of the battery cell 20 is not limited to this. In some embodiments, the battery cell 20 can also have other structures. For example, the outer casing 21 can include a housing 212 and an end cap 213. The housing 212 has a receiving cavity with an opening 2121 inside, and the electrode assembly 22 is received in the receiving cavity. The end cap 213 closes the opening 2121, and the end cap 213 is a wall portion 211. That is to say, the pressure relief mechanism 23 is provided on the end cap 213 of the outer casing 21.

[0341] In this embodiment, by setting the wall portion 211 of the outer casing 21 as an end cap 213 for closing the opening 2121, the battery cell 20 with this structure is convenient to set a pressure relief mechanism 23 on the end cap 213, which helps to reduce the manufacturing difficulty of the battery cell 20 and improve the production efficiency of the battery cell 20.

[0342] According to some embodiments of this application, this application also provides a battery device 100, which includes a battery cell 20 of any of the above schemes.

[0343] As shown in Figure 2, the battery device 100 may also include a housing 10, in which the battery cells 20 are housed.

[0344] In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, the first housing body 11 and the second housing body 12 covering each other, the first housing body 11 and the second housing body 12 together defining an assembly space for accommodating the battery cell 20.

[0345] Optionally, the second box body 12 can be a hollow structure with one end open, and the first box body 11 can be a plate-like structure. 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 together define the assembly space; the first box body 11 and the second box body 12 can 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.

[0346] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder or a cuboid. For example, in Figure 2, the box 10 is a cuboid structure.

[0347] Optionally, the battery cell 20 disposed within the housing 10 can be one or more. For example, in Figure 2, the housing 10 of the battery device 100 contains multiple battery cells 20. These multiple battery cells 20 can be connected in series, parallel, or a combination thereof. A combination thereof means that some of the multiple battery cells 20 are connected in series and others in parallel. Multiple battery cells 20 can be directly connected in series, parallel, or a combination thereof, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, parallel, or a combination thereof to form a battery module, and then these battery modules are connected in series, parallel, or a combination thereof to form a whole, which is then housed within the housing 10.

[0348] The battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar component that connects multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0349] It should be noted that in some embodiments, the battery device 100 may not have a housing 10. The battery device 100 includes multiple battery cells 20, and the battery device 100 composed of multiple battery cells 20 can be directly mounted onto the electrical device to provide power to the electrical device through the multiple battery cells 20. That is, the housing 10 can be part of the electrical device. Taking a vehicle 1000 as an example, the housing 10 can be part of the chassis structure of the vehicle 1000. For example, a portion of the housing 10 can be at least a part of the floor of the vehicle 1000, or a portion of the housing 10 can be at least a part of the crossbeams and longitudinal beams of the vehicle 1000.

[0350] According to some embodiments of this application, this application also provides an electrical device, which includes a battery cell 20 of any of the above schemes, and the battery cell 20 is used to provide electrical energy to the electrical device.

[0351] The electrical device can be any of the aforementioned devices or systems that utilize battery cells 20.

[0352] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0353] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A single battery cell, comprising: The outer shell has walls; Electrode assembly, housed within the housing; as well as A pressure relief mechanism is disposed on the wall portion. The pressure relief mechanism includes a weak portion and a connecting portion. The weak portion is configured to be at least partially destroyed to release the pressure when the pressure inside the housing reaches a threshold. The weak portion is annular, and the area enclosed by the weak portion is a pressure relief zone. The connecting portion includes a first portion and a second portion. The first portion is connected to the wall portion, and the second portion is connected to the weak portion and the first portion. The second part is bent into a plurality of sequentially connected bent segments, which surround the outside of the weak part, and the bent segments at both ends of the plurality of bent segments are respectively connected to the first part and the weak part.

2. The battery cell of claim 1, wherein, The first portion has opposing first and second surfaces in the thickness direction of the wall portion, and the second portion protrudes from the second surface along the direction from the first surface to the second surface; The pressure relief mechanism is provided with a groove, which is recessed from the first surface in a direction pointing from the first surface to the second surface. The second part, the weak part, and the pressure relief area together enclose at least a part of the groove.

3. The battery cell of claim 2, wherein, Within the cross-section of the connecting portion, the angle between the surfaces of two adjacent bent segments facing the groove is α, satisfying 90°≤α≤150°.

4. The battery cell of claim 3, wherein, 100°≤α≤140°。 5. The battery cell of any one of claims 2-4, wherein, The plurality of bending segments include a first bending segment connected to the first portion, wherein within the cross-section of the connection portion, the angle between the surface of the first bending segment facing away from the groove and the second surface is β, satisfying 80°≤β≤150°.

6. The battery cell of claim 5, wherein, 85°≤β≤100°。 7. The battery cell of any one of claims 2-6, wherein, Along the thickness direction of the wall portion, the second portion protrudes from the second surface by a dimension L1, satisfying 0.2mm≤L1≤7mm.

8. The battery cell of claim 7, wherein, 0.2mm≤L1≤5mm.

9. The battery cell of any one of claims 2-8, wherein, The second surface is disposed facing the electrode assembly along the thickness direction of the wall portion.

10. The battery cell of any one of claims 2-9, wherein, The surfaces of two adjacent bent segments facing the groove are connected by a first rounded corner surface; and / or The surfaces of two adjacent bent segments facing away from the groove are connected by a second rounded corner surface; and / or The plurality of bending segments include a first bending segment connected to the first portion, wherein the surface of the first bending segment facing the groove is connected to the first surface via a third rounded corner surface; and / or The plurality of bending segments include a first bending segment connected to the first portion, wherein the surface of the first bending segment facing away from the groove is connected to the second surface via a fourth rounded corner surface.

11. The battery cell of any one of claims 1-10, wherein, The wall thickness of the first part is T1, and the wall thickness of the bent section is T2, satisfying 0.8≤T2 / T1≤1.

1.

12. The battery cell of any one of claims 1-11, wherein, The wall thickness of the first part is T1, which satisfies 0.15mm≤T1≤0.5mm.

13. The battery cell of claim 12, wherein, 0.2mm≤T1≤0.3mm.

14. The battery cell of any one of claims 1-13, wherein, The plurality of bending segments include a first bending segment connected to the first portion and a second bending segment connected to the weak portion, wherein the wall thickness of the second bending segment is greater than the wall thickness of the first bending segment.

15. The battery cell of any one of claims 1-14, wherein, Along the thickness direction of the wall portion, the minimum thickness of the weak portion is D, which satisfies 0.01mm≤D≤0.2mm.

16. The battery cell of claim 15, wherein, In a projection plane perpendicular to the thickness direction of the wall, the area of ​​the orthographic projection of the pressure relief zone is S; wherein 100 mm 2 ≤ 450 mm 2 and 0.01 mm ≤ D ≤ 0.16 mm; or 350 mm 2 ≤ S ≤ 850 mm 2 and 0.015 mm ≤ D ≤ 0.17 mm; or 750 mm 2 ≤ S ≤ 1250 mm 2 and 0.02 mm ≤ D ≤ 0.18 mm; or 1150 mm 2 ≤ S ≤ 1650 mm 2 and 0.025 mm ≤ D ≤ 0.19 mm; or 1550 mm 2 ≤ S ≤ 2100 mm 2 and 0.03 mm ≤ D ≤ 0.2 mm.

17. The battery cell of any one of claims 1-16, wherein, The weak part includes a first weak segment and a second weak segment connected end to end. Along the thickness direction of the wall, the thickness of the second weak segment is greater than the thickness of the first weak segment.

18. The battery cell of claim 17, wherein, The weak section includes two arc segments and two straight segments. One arc segment, one straight segment, another arc segment, and another straight segment are connected end to end. The two arc segments are arranged opposite each other along a first direction and extend along an arc trajectory. The two straight segments are arranged opposite each other along a second direction and extend along the first direction. The first direction, the second direction, and the thickness direction of the wall are perpendicular to each other. The first weak segment includes two arc segments and one straight segment, and the second weak segment is another straight segment.

19. The battery cell of any one of claims 1-18, wherein, Along the thickness direction of the wall portion, at least a portion of the pressure relief area bulges towards or away from the electrode assembly to form a raised portion, and the weak portion surrounds the outside of the raised portion.

20. The battery cell of claim 19, wherein, At least a portion of the boundary of the raised portion is adjacent to the boundary of the weak portion.

21. The battery cell of claim 19 or 20, wherein, The first part has opposing first and second surfaces in the thickness direction of the wall portion, the second part protrudes from the second surface in the direction from the first surface to the second surface, the pressure relief mechanism is provided with a groove, the groove is recessed from the first surface in the direction from the first surface to the second surface, and the second part, the weak part and the pressure relief area together enclose at least a portion of the groove; In the thickness direction of the wall portion, the raised portion protrudes along the direction from the second surface to the first surface.

22. The battery cell of claim 21, wherein, In the thickness direction of the wall portion, the raised portion does not extend beyond the first surface in the direction from the second surface to the first surface.

23. The battery cell of any one of claims 19-22, wherein, The raised portion includes a first region and two second regions. The two second regions are arranged at intervals along a first direction and are respectively connected to the two ends of the first region. The outer surface of the raised portion is recessed to form a recessed area. The recessed direction of the recessed area is opposite to the raised direction of the raised portion, and the recessed area is located within the first region. The first direction is perpendicular to the thickness direction of the wall portion.

24. The battery cell of claim 23, wherein, The weak part includes two arc segments and two straight segments. One arc segment, one straight segment, another arc segment, and another straight segment are connected end to end. The two arc segments are arranged opposite each other along the first direction and extend along the arc trajectory. The two straight segments are arranged opposite each other along the second direction and extend along the first direction. The first direction, the second direction, and the thickness direction of the wall are perpendicular to each other. The areas where the raised portion connects to the two arc segments are the two second areas, and the areas where the raised portion connects to the two straight segments are the first areas.

25. The battery cell of claim 24, wherein, In a projection plane perpendicular to the thickness direction of the wall, the orthographic projection of the first region is a rectangle, and the orthographic projection of the second region is a semicircle.

26. The battery cell of any one of claims 23-25, wherein, Along the thickness direction of the wall portion, the maximum recess depth of the recessed area is H, which satisfies 0.05mm≤H≤1mm.

27. The battery cell of claim 26, wherein, 0.1mm≤H≤0.5mm.

28. The battery cell of any one of claims 23-27, wherein, The maximum dimension of the second region in the thickness direction of the wall is L2, which satisfies 0.5mm≤L2≤3mm.

29. The battery cell of claim 28, wherein, 0.7mm≤L2≤1.6mm.

30. The battery cell of any one of claims 1-29, wherein, The pressure relief mechanism is provided with a pressure relief groove, and the bottom wall of the pressure relief groove forms the weak part.

31. The battery cell of any one of claims 1-30, wherein, The pressure relief mechanism is separately disposed from the wall portion; or The pressure relief mechanism is integrally formed with the wall portion.

32. A battery device comprising a battery cell as claimed in any one of claims 1-31.

33. An electrical device comprising a battery cell as claimed in any one of claims 1-31, the battery cell being used to provide electrical energy.

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