Battery monomer, battery and electric equipment

Abstract

The invention discloses a battery monomer (20), a battery (100) and electric equipment. The battery monomer (20) comprises a shell (21) and a pressure relief component (22), the shell (21) comprises a first wall portion (211), the pressure relief component (22) is arranged on the first wall portion (211), the pressure relief component (22) is provided with a first groove (221), the first groove (221) is recessed from a first surface (2111) in the thickness direction of the first wall portion (211) to a direction close to a second surface (2112), the first groove (221) defines at least one preset pressure relief area (P), and the first wall portion (211) is provided with a second surface (2112). The pressure relief component (22) is configured to be capable of cracking along at least part of the first groove (221) when the battery monomer (20) is subjected to pressure relief; wherein the sum S1 of the areas of all the preset pressure relief areas (P) is 0.03-0.3 times of the area S2 of the first surface (2111), so that the risks of burst, explosion, fire and the like of the shell (21) of the battery monomer (20), which are caused by the fact that the pressure relief component (22) does not relieve the pressure in time, can be reduced; and the risk of liquid leakage caused by the phenomena such as advanced actuation or fatigue cracking of the pressure relief component (22) after the battery monomer (20) is used for a long time is reduced, and the service life of the battery monomer (20) is prolonged and the use reliability of the battery monomer (20) is improved.

Description

Battery cells, batteries and electrical equipment Technical Field

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

[0002] Batteries are widely used in new energy vehicles, electronic equipment and other fields. As the demand for batteries increases, higher requirements are placed on battery reliability.

[0003] In battery technology, the pressure relief components of battery cells are a key factor affecting their reliability. These components are used to release pressure within the battery cells when the pressure or temperature inside the cells reaches a threshold. However, after repeated cycles and long-term use, these components are prone to premature activation or fatigue cracking, reducing the reliability of the battery cells.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide a battery cell, a battery, and an electrical device to improve the reliability of the battery cell.

[0006] In a first aspect, an embodiment of the present application provides a battery cell, comprising a shell and a pressure relief component; the shell comprises a first wall portion, and in a thickness direction of the first wall portion, the first wall portion has a first surface and a second surface arranged opposite to each other; the pressure relief component is arranged on the first wall portion, and the pressure relief component is provided with a first groove, and the first groove is recessed from the first surface toward the direction close to the second surface, and the first groove defines at least one predetermined pressure relief area, and the pressure relief component is configured to be able to split along at least part of the first groove when the battery cell is depressurized; wherein the sum S1 of the areas of all the predetermined pressure relief areas is 0.03 to 0.3 times the area S2 of the first surface.

[0007] In the above technical solution, the first wall of the shell is provided with a pressure relief component, which includes a first weak portion. The first weak portion can be broken when the battery cell is depressurized to release the pressure inside the battery cell, so as to reduce the problems such as explosion and fire caused by excessive pressure inside the battery cell. By setting the sum of the areas S1 of all the predetermined pressure relief zones to 0.03 to 0.3 times the area S2 of the first surface provided with the first groove, that is, the ratio of the sum of the areas S1 of all the predetermined pressure relief zones to the area S2 of the first surface provided with the first groove is set to 0.03 to 0.3, the relative sizes of the sum of the areas S1 of all the predetermined pressure relief zones and the area S2 of the first surface provided with the first groove are set more reasonably. Setting the ratio to be greater than or equal to 0.03 can alleviate the problem of insufficient area of ​​the predetermined pressure relief zones, thereby alleviating the phenomenon that the pressure bearing capacity of the bottom wall of the first groove is too large, resulting in excessive bursting pressure required by the pressure relief component when the battery cell is relieved of pressure, thereby reducing the risk of bursting, explosion, fire, etc. of the battery cell shell due to untimely pressure relief of the pressure relief component, and thus effectively improving the reliability of the battery cell. The expansion force generated by the expansion of the battery cell during use will cause the first wall portion to deform. Setting the ratio to less than or equal to 0.3 can alleviate the problem of the first wall portion being easily deformed due to the reduced strength and rigidity of the predetermined pressure relief area being too large relative to the first surface area. It can also reduce the concentration of stress on the bottom wall of the first groove when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component, and enable the predetermined pressure relief area to absorb a portion of the expansion force, thereby effectively alleviating the occurrence of tensile deformation and other phenomena on the bottom wall of the first groove of the pressure relief component, thereby reducing the strain and strain amplitude of the bottom wall of the first groove of the pressure relief component, that is, reducing the deformation of the bottom wall of the first groove, and thereby alleviating the phenomenon of the structural strength of the bottom wall of the first groove of the pressure relief component being reduced due to excessive strain and strain amplitude, thereby reducing the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component in the corresponding area of ​​the first groove after long-term use of the battery cell. This improves the stability of the pressure relief component in use and is conducive to improving the service life and reliability of the battery cell.

[0008] In some embodiments of the first aspect of the present application, 500 mm 2 ≤S1≤1300mm 2 .

[0009] In the above technical solution, the sum of the areas S1 of all the predetermined pressure relief zones is limited to 500mm 2 Up to 1300mm 2 , the sum of the areas of all predetermined pressure relief zones S1 is set to be greater than or equal to 500mm 2, can alleviate the problem of insufficient area of ​​the predetermined pressure relief area, so as to alleviate the phenomenon that the pressure relief component requires too much bursting pressure when the battery cell is depressurized due to the excessive pressure bearing capacity of the bottom wall of the first groove, thereby reducing the risk of bursting, explosion, fire, etc. of the battery cell shell due to untimely pressure relief of the pressure relief component, and further effectively improve the reliability of the battery cell. The sum of the areas of all predetermined pressure relief areas is set to be less than or equal to 1300mm 2 , which can alleviate the problem that the strength of the first wall portion is reduced and large deformation occurs easily due to the large area of ​​the predetermined pressure relief area. It can also reduce the concentration of stress on the bottom wall of the first groove when the expansion force generated by expansion during the use of the battery cell acts on the pressure relief component, and enable the predetermined pressure relief area to absorb part of the expansion force, thereby effectively alleviating the tensile deformation and other phenomena of the bottom wall of the first groove of the pressure relief component, thereby reducing the strain and strain amplitude of the bottom wall of the first groove of the pressure relief component, that is, it can reduce the deformation of the bottom wall of the first groove, and thus alleviate the phenomenon that the structural strength of the bottom wall of the first groove of the pressure relief component is reduced due to excessive strain and strain amplitude, thereby reducing the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component in the corresponding area of ​​the first groove after long-term use of the battery cell. It can improve the stability of the pressure relief component and is beneficial to improving the service life and reliability of the battery cell.

[0010] In some embodiments of the first aspect of the present application, 5000 mm 2 ≤S2≤8500mm 2 .

[0011] In the above technical solution, by setting the area S2 of the first surface where the first groove is set to 6000mm 2 Up to 8500mm 2 , the area of ​​the first surface is set to be greater than or equal to 6000mm 2, which can alleviate the problem of large deformation caused by the reduced strength of the first wall due to the small area of ​​the first surface. It can also reduce the concentration of stress on the bottom wall of the first groove when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component, and enable the predetermined pressure relief area to absorb part of the expansion force, thereby effectively alleviating the phenomenon of tensile deformation of the bottom wall of the first groove of the pressure relief component, thereby reducing the strain and strain amplitude of the bottom wall of the first groove of the pressure relief component, that is, reducing the deformation of the bottom wall of the first groove, thereby alleviating the phenomenon of reduced structural strength of the bottom wall of the first groove of the pressure relief component due to excessive strain and strain amplitude, thereby reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component in the corresponding area of ​​the first groove after long-term use of the battery cell, thereby improving the use stability of the pressure relief component and helping to improve the service life and reliability of the battery cell. The area of ​​the first surface is set to be less than or equal to 8500mm 2 , which can alleviate the problem that the first surface area is too small, resulting in the first wall having greater strength and rigidity and being able to withstand greater pressure but difficult to deform, and alleviate the phenomenon that the pressure bearing capacity of the bottom wall of the first groove is too large, resulting in the pressure relief component requiring too large an explosion pressure when the battery cell is relieved, thereby reducing the risk of bursting, explosion, fire, etc. of the battery cell shell due to untimely pressure relief of the pressure relief component, and further effectively improving the reliability of the battery cell.

[0012] In some embodiments of the first aspect of the present application, the first wall portion is a rectangular wall portion; along the width direction of the first wall portion, the size of the first surface is c; along the length direction of the first wall portion, the size of the first surface is d, S2=c*d; wherein, 55mm≤c≤85mm, 100mm≤d≤260mm.

[0013] In the above technical solution, the first wall portion is a rectangular wall portion, which is convenient for manufacturing and molding, and also convenient for measuring the area of ​​the first surface.

[0014] In some embodiments of the first aspect of the present application, the first wall portion is a rectangular wall portion; along the length direction of the first wall portion, the pressure relief component forms at least one predetermined pressure relief area, and the sum of the sizes a of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is 0.1 times to 0.5 times the size d of the first surface along the length direction of the first wall portion.

[0015] In the above technical solution, the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is 0.1 to 0.5 times the size d of the first surface along the length direction of the first wall portion, that is, the ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the size d of the first surface in the length direction of the first wall portion is limited to 0.1 to 0.5, wherein the ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the size d of the first surface in the length direction of the first wall portion is greater than or equal to 0.1, which can alleviate the phenomenon that the pressure bearing capacity of the bottom wall of the first groove is too large, resulting in excessive bursting pressure required by the pressure relief component when the battery cell is relieved, thereby reducing the risk of bursting, explosion, fire, etc. of the battery cell shell due to untimely pressure relief of the pressure relief component, and further effectively improving the reliability of the battery cell. The ratio of the sum a of the sizes of all predetermined pressure relief areas arranged along the length direction of the first wall portion to the size d of the first surface in the length direction of the first wall portion is less than or equal to 0.5, which can reduce the deformation of the bottom wall of the first groove when the expansion force generated by expansion during the use of the battery cell acts on the pressure relief component, thereby reducing the structural strength of the bottom wall of the first groove of the pressure relief component due to excessive deformation, and further reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component at the corresponding position of the first groove after long-term use of the battery cell, thereby improving the stability of the pressure relief component in use. Qualitatively, the service life and reliability of the battery cell are improved. Therefore, the sum of the sizes a of all predetermined pressure relief areas arranged along the length direction of the first wall portion is 0.1 to 0.5 times the size d of the first surface along the length direction of the first wall portion. This can take into account both reducing the risks of bursting, explosion, fire, etc. of the battery cell shell due to untimely pressure relief of the pressure relief component, and reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component at the corresponding position of the first groove of the battery cell after long-term use, so as to improve the stability of the pressure relief component and improve the service life and reliability of the battery cell.

[0016] In some embodiments of the first aspect of the present application, the first wall portion is a rectangular wall portion; along the width direction of the first wall portion, the first groove defines at least one predetermined pressure relief area, and the sum of the sizes b of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is 0.3 times to 0.7 times the size c of the first surface along the width direction of the first wall portion.

[0017] In the above technical solution, the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is 0.3 to 0.7 times the size c of the first surface along the width direction of the first wall portion, that is, the ratio of the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion to the size of the first surface in the curling direction of the first wall portion is limited to 0.3 to 0.7. Among them, by making the ratio of the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion to the size of the first surface in the curling direction of the first wall portion greater than or equal to 0.3, the phenomenon that the pressure bearing capacity of the bottom wall of the first groove is too large, resulting in the pressure relief component requiring too large an explosion pressure when the battery cell is depressurized, can be alleviated, thereby reducing the risk of bursting, explosion, fire, etc. of the battery cell shell due to untimely pressure relief of the pressure relief component, and further effectively improving the reliability of the battery cell. By making the ratio of the sum of the sizes b of all predetermined pressure relief areas arranged along the width direction of the first wall portion to the size of the first surface in the curl direction of the first wall portion less than or equal to 0.7, the degree of material stacking in the width direction of the first wall portion during the manufacture of the first groove can be reduced, thereby alleviating the problem of poor flatness of the surface of the battery cell in the width direction of the first wall portion due to the formation of the first groove.

[0018] In some embodiments of the first aspect of the present application, the first wall portion is a rectangular wall portion; along the length direction of the first wall portion, the pressure relief component forms at least one predetermined pressure relief area, and the sum of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is a, 26mm≤a≤50mm.

[0019] In the above technical solution, the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is greater than or equal to 26 mm, which not only facilitates the processing and forming of the first groove and defines the predetermined pressure relief area, but also helps to increase the area of ​​the predetermined pressure relief area, thereby alleviating the phenomenon that the pressure-bearing capacity of the bottom wall of the first groove is too large, resulting in the pressure relief component requiring an excessively large bursting pressure when the battery cell is relieved of pressure, thereby reducing the risk of bursting, explosion, fire, etc. of the battery cell shell due to untimely pressure relief of the pressure relief component, and further effectively improving the reliability of the battery cell. The sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is less than or equal to 50 mm, which can reduce the deformation of the bottom wall of the first groove when the expansion force generated by expansion during the use of the battery cell acts on the pressure relief component, thereby reducing the structural strength of the bottom wall of the first groove of the pressure relief component due to excessive deformation, and further reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component at the corresponding position of the first groove after long-term use of the battery cell, thereby improving the use stability of the pressure relief component and improving the service life and reliability of the battery cell.

[0020] In some embodiments of the first aspect of the present application, the first wall portion is a rectangular wall portion; along the width direction of the first wall portion, the first groove defines at least one predetermined pressure relief area, and the sum of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is b, where 18 mm ≤ b ≤ 62 mm.

[0021] In the above technical solution, the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is greater than or equal to 18 mm, which not only facilitates the processing and forming of the first groove to define the predetermined pressure relief area, but also helps to increase the area of the predetermined pressure relief area, alleviating the phenomenon that the pressure-bearing capacity of the bottom wall of the first groove is too large, resulting in an excessive bursting pressure required for the pressure relief component during the pressure relief of the battery cell. Thus, it can reduce the risks such as bursting, explosion, and fire of the outer shell of the battery cell caused by untimely pressure relief of the pressure relief component, and further effectively improve the reliability of use of the battery cell. The sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is less than or equal to 62 mm, which can reduce the degree of material accumulation in the width direction of the first wall portion during the manufacturing process of the first groove, thereby alleviating the problem of poor flatness of the surface of the battery cell in the width direction of the first wall portion due to the formation of the first groove.

[0022] In some embodiments of the first aspect of the present application, the first wall portion is a rectangular wall portion; along the length direction of the first wall portion, the pressure relief component forms at least one predetermined pressure relief area, and the sum of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is a; along the width direction of the first wall portion, the first groove defines at least one predetermined pressure relief area, and the sum of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is b, and along the width direction of the first wall portion, the size of the first surface is c; when 10 mm ≤ c ≤ 40 mm, the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is 2 to 3 times the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion; when 40 mm < c ≤ 60 mm, the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is 1 to 2 times the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion; when 60 mm < c, the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is 0.4 to 1 times the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion.

[0023] In the above technical solution, when 10mm ≤ c ≤ 40mm, the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is 2 to 3 times the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion, that is, the ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is 2 to 3. The ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is greater than or equal to 2, and the bursting pressure is more stable, which is beneficial for the pressure relief component to relieve pressure in time, so as to reduce the risks such as the bursting, explosion, and fire of the outer shell of the battery cell caused by the untimely pressure relief of the pressure relief component, and further effectively improve the use reliability of the battery cell; the ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is less than or equal to 3, which is beneficial for a larger opening valve angle of the predetermined pressure relief area when the first groove cracks, so that the pressure relief component has a larger pressure relief area, thus being beneficial for the pressure relief component to relieve pressure in time, reducing the risks such as the bursting, explosion, and fire of the outer shell of the battery cell, and improving the reliability of the battery cell. When 40mm < c ≤ 60mm, the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is 1 to 2 times the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion, that is, the ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is 1 to 2. The ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is greater than or equal to 1, and the bursting pressure is more stable, which is beneficial for the pressure relief component to relieve pressure in time, so as to reduce the risks such as the bursting, explosion, and fire of the outer shell of the battery cell caused by the untimely pressure relief of the pressure relief component, and further effectively improve the use reliability of the battery cell; the ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is less than or equal to 2, which is beneficial for a larger opening valve angle of the predetermined pressure relief area when the first groove cracks, so that the pressure relief component has a larger pressure relief area, thus being beneficial for the pressure relief component to relieve pressure in time, reducing the risks such as the bursting, explosion, and fire of the outer shell of the battery cell, and improving the reliability of the battery cell.When 60mm < c, the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion is 0.4 times to 1 times the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion, that is, the ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is 0.4 to 1. The ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is greater than or equal to 0.4, and the bursting pressure is more stable, which is beneficial to the timely pressure relief of the pressure relief component, so as to reduce the risks such as the bursting, explosion, and fire of the outer shell of the battery cell caused by the untimely pressure relief of the pressure relief component, and thus can effectively improve the use reliability of the battery cell; the ratio of the sum a of the sizes of all the predetermined pressure relief areas arranged along the length direction of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas arranged along the width direction of the first wall portion is less than or equal to 1, which is beneficial to a larger opening angle of the predetermined pressure relief area when the first groove cracks, so that the pressure relief component has a larger pressure relief area, which is beneficial to the timely pressure relief of the pressure relief component, reduces the risks such as the bursting, explosion, and fire of the outer shell of the battery cell, and improves the reliability of the battery cell.

[0024] In some embodiments of the first aspect of the present application, the pressure relief component further includes a second groove, and the second groove is configured to guide the opening of the predetermined pressure relief area.

[0025] In the above technical solution, since the pressure relief component is provided with the second groove, a weak part is formed in the area corresponding to the second groove of the pressure relief component. The weak part corresponding to the second groove can guide the opening of the predetermined pressure relief area, so as to improve the opening effect of the predetermined pressure relief area of the pressure relief component, which is beneficial to increasing the pressure relief area of the battery cell after the predetermined pressure relief area is opened, and further can increase the pressure relief rate of the battery cell when thermal runaway occurs, so as to reduce the risks such as fire explosion and connection failure caused by the untimely pressure relief of the battery cell, and is beneficial to improving the use reliability of the battery cell. The pressure relief component is provided with the second groove, so that a weak part is formed in the area where the second groove is provided and the bottom surface of the second groove corresponds. The battery cell with this structure is convenient to form a weak part on the pressure relief component, which is beneficial to reducing the difficulty of forming a weak part on the pressure relief component to guide the opening of the predetermined pressure relief area, so as to improve the production efficiency of the battery cell.

[0026] In some embodiments of the first aspect of the present application, the second groove is recessed from the second surface towards the direction close to the first surface.

[0027] In the above technical solution, the second groove is recessed from the second surface toward the first surface, and the first groove and the second groove are arranged on opposite sides of the pressure relief component along the thickness direction of the first wall portion, so as to facilitate the processing of the first groove and the second groove on both sides of the pressure relief component along the thickness direction of the first wall portion, respectively, which is beneficial to reduce the mutual influence of the first groove and the second groove during the processing process.

[0028] In some embodiments of the first aspect of the present application, the first surface is a surface of the pressure relief component facing away from the interior of the housing, and the second surface is a surface of the pressure relief component facing the interior of the housing.

[0029] In the above technical solution, by arranging the first and second grooves on the first and second surfaces of the pressure relief component, which are opposite to each other along the thickness direction of the first wall portion, respectively, it is convenient to process the first and second grooves on both sides of the pressure relief component along the thickness direction of the first wall portion, thereby reducing the mutual influence between the first and second grooves during the processing. In addition, the second groove is arranged on the second surface of the pressure relief component facing the interior of the housing, so that the predetermined pressure relief area can be flipped toward the outside of the housing around the bottom wall of the second groove after being opened. This can reduce the interference caused by the groove side of the second groove on the predetermined pressure relief area during the flipping process, thereby improving the flipping effect of the predetermined pressure relief area.

[0030] In some embodiments of the first aspect of the present application, the first groove and the second groove do not contact each other.

[0031] In the above technical solution, by setting the first groove and the second groove to a structure that does not contact each other, on the one hand, the mutual influence between the first groove and the second groove during the processing can be reduced; on the other hand, the phenomenon of the corresponding area of ​​the second groove cracking when the first groove cracks to release pressure can be reduced, and the stress influence between the first groove and the second groove can be reduced.

[0032] In some embodiments of the first aspect of the present application, the first groove includes a first groove segment and a second groove segment, the first groove segment and the second groove segment are connected, and the first groove segment and the second groove segment jointly define at least one predetermined pressure relief area.

[0033] In the above technical solution, the first groove includes a first groove section and a second groove section, and the first groove section and the second groove section are interconnected structures. On the one hand, it can increase the pressure relief area of ​​the battery cell to increase the pressure relief rate of the battery cell. On the other hand, it makes the position where the first groove section and the second groove section are interconnected weaker, which is easier to crack and open the predetermined pressure relief area to release the internal pressure of the battery cell.

[0034] In some embodiments of the first aspect of the present application, the first groove further includes a third groove segment, the first groove segment and the third groove segment are arranged opposite to each other, the second groove segment connects the first groove segment and the third groove segment, and the first groove segment, the second groove segment and the third groove segment jointly define at least one predetermined pressure relief area.

[0035] In the above technical solution, the first groove is provided with a first groove section and a third groove section arranged opposite to each other, and a second groove section connecting the first groove section and the third groove section, so that the pressure relief component can split along the first groove section, the second groove section and the third groove section when the battery cell is pressure-relieved, so as to open the predetermined pressure relief area to release the internal pressure of the battery cell. The first groove with such a structure makes the intersection position of the first groove section and the second groove section and the intersection position of the second groove section and the third groove section weaker, easier to split and open the predetermined pressure relief area for pressure relief, and can further improve the pressure relief area and pressure relief rate of the battery cell.

[0036] In some embodiments of the first aspect of the present application, the position where the second slot segment is connected to the first slot segment deviates from the two ends of the first slot segment, and the position where the second slot segment is connected to the third slot segment deviates from the two ends of the third slot segment.

[0037] In the above technical solution, the position where the second groove segment is connected to the first groove segment deviates from the two ends of the first groove segment, and the connection position between the first groove segment and the second groove segment is set to be located between the two ends of the first groove segment. The position where the second groove segment is connected to the third groove segment deviates from the two ends of the third groove segment, and the connection position between the third groove segment and the second groove segment is set to be located between the two ends of the third groove segment. The first groove segment, the second groove segment and the third groove segment form an "H"-shaped structure, so that predetermined pressure relief areas can be formed on both sides of the second groove segment of the first groove, and the two predetermined pressure relief areas can be opened in a split manner for pressure relief when the battery cell is depressurized, which is beneficial to further increase the pressure relief effect of the battery cell and can effectively improve the pressure relief rate of the battery cell.

[0038] In some embodiments of the first aspect of the present application, the first groove defines two predetermined pressure relief areas, and the two predetermined pressure relief areas are respectively located on both sides of the second groove section; the pressure relief component also includes a second groove, and the second groove is configured to guide the predetermined pressure relief area to open, and each predetermined pressure relief area corresponds to at least one second groove, and the first groove is located between the two second grooves.

[0039] In the above technical solution, the second groove can guide the corresponding predetermined pressure relief area to open, and at least one second groove is provided corresponding to each predetermined pressure relief area, thereby improving the opening effect of each predetermined pressure relief area of ​​the pressure relief component, which is beneficial to increasing the pressure relief area of ​​the battery cell after the predetermined pressure relief area is opened, and further improving the pressure relief rate of the battery cell when thermal runaway occurs, so as to reduce the risk of fire, explosion, connection failure, etc. caused by untimely pressure relief of the battery cell, and is beneficial to improving the reliability of the battery cell.

[0040] In some embodiments of the first aspect of the present application, the second slot segment and the second groove are arranged opposite to each other along a first direction, and along the first direction, the first slot segment and the third slot segment are both arranged spaced apart from the second groove.

[0041] In the above technical solution, the second groove section and the second groove are arranged opposite each other along the first direction, and the first groove section and the third groove section are spaced apart from the second groove along the first direction. Therefore, the first groove section, the second groove section, and the third groove section do not contact the second groove, which can reduce the mutual influence between the first groove and the second groove during processing, and reduce the phenomenon of cracking in the area corresponding to the second groove when the first groove cracks and releases pressure, and can also reduce the stress effect between the first groove and the second groove. The second groove section and the second groove are arranged opposite each other along the first direction, and the first groove section and the third groove section are spaced apart from the second groove along the first direction. Therefore, the second groove is located between the edge of the first wall portion along the first direction and the first notch. The second groove can act as a buffer between the first groove and the edge of the first wall portion along the first direction, reducing the risk of the first groove cracking due to external force, and improving the reliability of the battery cell.

[0042] In some embodiments of the first aspect of the present application, the first wall portion is a rectangular wall portion, and the first direction is parallel to a width direction of the first wall portion.

[0043] In the above technical solution, the first direction is parallel to the width direction of the first wall portion, and the second groove section is arranged opposite the second groove along the width direction of the first wall portion. The first groove section and the third groove section are both spaced apart from the second groove along the width direction of the first wall portion, and the first, second, and third groove sections do not contact the second groove along the width direction of the first wall portion. This can reduce the mutual influence between the first and second grooves during processing, reduce the phenomenon that the area corresponding to the first groove causes the area corresponding to the second groove to crack during pressure relief, and reduce the stress effect between the first and second grooves. The second groove section and the second groove are arranged opposite each other along the width direction of the first wall portion, and the first and third groove sections are both spaced apart from the second groove along the width direction of the first wall portion. The second groove is located between the edge of the first wall portion along the width direction of the first wall portion and the first notch. The second groove can act as a buffer between the first groove and the edge of the first wall portion in the first direction, reducing the risk of the first groove cracking due to external forces, and improving the reliability of the battery cell.

[0044] In some embodiments of the first aspect of the present application, the first groove is a multi-level notch groove, which is a multi-level notch groove arranged in sequence along the direction from the first surface to the second surface. In two adjacent levels of the notch grooves, the first-level notch groove away from the first surface is arranged at the bottom surface of the first-level notch groove close to the first surface.

[0045] In the above technical solution, the first groove is set as a stepped groove structure set along the thickness direction of the wall portion, so that the first groove is a groove formed by multiple processing. When this structure is used to form grooves of the same depth in the pressure relief component, on the one hand, the depth of the single processing of the notched groove can be reduced, which is beneficial to reducing the manufacturing difficulty and demand for manufacturing equipment for forming grooves of the same depth, so as to reduce manufacturing costs, and can reduce the forming force that the pressure relief component is subjected to in a single processing during the formation of the first groove, which is beneficial to reducing the risk of cracks in the pressure relief component, so as to improve the production quality of the battery cell, and on the other hand, it can improve the flow shape of the bottom wall of the first groove during the formation process, which is beneficial to the flow of materials generated when forming the bottom wall of the first groove, so as to improve the structural consistency of the multi-stage notched groove.

[0046] In some embodiments of the first aspect of the present application, the first groove is a three-level scoring groove, and the three-level scoring grooves are arranged in sequence from the first surface to the second surface.

[0047] In the above technical solution, the first groove is a three-level scoring groove. When forming grooves of the same depth, it can reduce the depth of the scoring groove in a single processing, which is beneficial to reducing the manufacturing difficulty and demand for manufacturing equipment for forming grooves of the same thickness, so as to reduce manufacturing costs, and can reduce the forming force that the pressure relief component is subjected to in a single processing during the formation of the bottom wall of the first groove, which is beneficial to reducing the risk of cracks in the pressure relief component, so as to improve the production quality of the battery cell. On the other hand, it can improve the flow shape of the bottom wall of the first groove during the formation process, which is beneficial to the flow of materials generated when forming the first groove, so as to improve the structural consistency of the multi-level scoring grooves; it also alleviates the problem of increased processing time due to multiple processing required for the formation of the first groove.

[0048] In some embodiments of the first aspect of the present application, the pressure relief component is integrally formed with the first wall portion.

[0049] In the above technical solution, the pressure relief component and the first wall portion are arranged as an integrally formed structure, so that the pressure relief component is a structure integrated on the first wall portion, that is, the pressure relief component is a wall of the shell, and correspondingly, the pressure relief component is arranged on the first wall portion. The battery cell adopting this structure can improve the structural strength of the pressure relief component arranged on the first wall portion, and can reduce the risk of leakage between the pressure relief component and the first wall portion due to improper assembly.

[0050] In some embodiments of the first aspect of the present application, the pressure relief component is separately provided from the first wall portion, the first wall portion is provided with a pressure relief hole, and the pressure relief component is installed on the first wall portion and covers the pressure relief hole.

[0051] In the above technical solution, by arranging the pressure relief component and the first wall portion as a separate structure, the pressure relief component is a structure installed on the first wall portion. The battery cell adopting this structure can reduce the difficulty of setting the pressure relief component on the first wall portion, and the processing steps of the shell and the pressure relief component can be carried out simultaneously, which is conducive to optimizing the production rhythm of the battery cell.

[0052] In some embodiments of the first aspect of the present application, the battery cell includes an electrode assembly, the electrode assembly is accommodated in the housing, and the first wall portion supports the electrode assembly.

[0053] In the above technical solution, the first wall supports the electrode assembly, and the pressure relief component is arranged on the first wall, which can reduce the risk of the released substance acting on other electrical connection structures when the battery cell is depressurized, thereby reducing the risk of causing other reliability problems.

[0054] In some embodiments of the first aspect of the present application, the battery cell includes an electrode terminal, and the electrode terminal is provided on a wall portion of the housing other than the first wall portion.

[0055] In the above technical solution, the electrode terminals are arranged on other walls of the shell except the first wall, so the risk of the substances discharged from the battery cell when the pressure is released acts on the electrode terminals is low, which can reduce the risk of the battery cell short circuiting and causing thermal runaway of the battery cell again due to the electrical connection formed by the substances discharged from the battery cell when the pressure is released and the electrode terminals.

[0056] In some embodiments of the first aspect of the present application, the electrode terminal is disposed on a wall of the housing opposite to the first wall portion.

[0057] In the above technical solution, the electrode terminal is arranged on the wall portion of the shell opposite to the first wall portion, so that the distance between the electrode terminal and the pressure relief component is farther, which can further reduce the risk of the discharged substance of the battery cell acting on the electrode terminal when the battery cell is depressurized, and further reduce the risk of the battery cell short circuit caused by the formation of electrical connection between the discharged substance and the electrode terminal when the battery cell is depressurized, causing the battery cell to short-circuit again and cause thermal runaway of the battery cell.

[0058] In some embodiments of the first aspect of the present application, the housing includes a shell and an end cover; the shell has at least one opening; the end cover corresponds to the opening one by one, and the end cover is connected to the shell and closes the opening; wherein, at least one of the end covers is the first wall portion, or the shell includes the first wall portion.

[0059] In the above technical solution, by configuring the first wall portion of the housing as an end cap for closing the opening of the housing, a battery cell employing this structure facilitates the provision of a pressure relief component on the end cap, thereby reducing the manufacturing difficulty of the battery cell and improving the production efficiency of the battery cell. By configuring the first wall portion of the housing as a wall portion of the shell, a battery cell employing this structure can position the area of ​​the housing where the pressure relief component is provided away from the end cap, thereby effectively alleviating the stress generated by the connection between the end cap and the shell acting on the pressure relief component, thereby reducing the impact on the predetermined pressure relief area of ​​the pressure relief component and the area corresponding to the first groove, thereby facilitating the reduction of the risk of cracking or a decrease in structural strength of the pressure relief component under the pulling effect of stress, thereby improving the service life and reliability of the battery cell.

[0060] In some embodiments of the first aspect of the present application, the shell has two openings arranged opposite to each other; the outer shell includes two end covers, each end cover is connected to the shell and closes one opening, and the shell includes the first wall portion.

[0061] In the above technical solution, the housing has two openings arranged opposite each other, and the two end caps respectively seal the two openings. This structure facilitates assembly of the battery cells from both ends of the housing, which helps reduce the difficulty of manufacturing and assembling the battery cells. The housing includes a first wall portion, and the pressure relief components are not provided on the end caps. This can reduce the risk of substances released from the battery cells during pressure relief from interacting with other battery structures, further reducing the risk of thermal runaway of the battery cells due to the formation of electrical connection between the substances released from the battery cells during pressure relief and the electrode terminals, causing a short circuit in the battery cells.

[0062] In some embodiments of the first aspect of the present application, the shell has an opening, and a wall portion of the shell arranged opposite to the opening is the first wall portion.

[0063] In the above technical solution, the wall portion of the shell that is arranged opposite to the opening is the first wall portion, which can reduce the risk of the substance released when the battery cell is depressurized acting on other structures of the battery, thereby further reducing the risk of the battery cell short circuiting due to the electrical connection formed by the substance released when the battery cell is depressurized and the electrode terminals causing thermal runaway of the battery cell again.

[0064] In some embodiments of the first aspect of the present application, the material of the pressure relief component includes steel.

[0065] In the above technical solution, the pressure relief component is made of steel. Steel has high strength, and the pressure relief component made of steel has better strength. Under the condition of a certain burst pressure of the battery cell, the pressure relief component can be made thinner, reducing the volume of the pressure relief component.

[0066] In some embodiments of the first aspect of the present application, the steel material is carbon steel or stainless steel.

[0067] In some embodiments of the first aspect of the present application, the material of the pressure relief component includes aluminum alloy.

[0068] In the above technical solution, aluminum alloy has the characteristics of light weight and good ductility, and it is easier to process the first groove on the pressure relief component.

[0069] In some embodiments of the first aspect of the present application, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other single elements ≤ 0.03%.

[0070] In the above technical solution, the aluminum alloy has lower hardness and better forming ability, which reduces the difficulty of processing the first groove, is conducive to improving the processing accuracy of the first groove, and improves the pressure relief consistency of the pressure relief component.

[0071] In some embodiments of the first aspect of the present application, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 96.7%, 0.05% ≤ copper ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other single element components ≤ 0.05%, and the total composition of other elements ≤ 0.15%.

[0072] In the above technical solution, the pressure relief component made of this aluminum alloy has higher hardness, greater strength and good anti-destruction ability.

[0073] In a second aspect, an embodiment of the present application further provides a battery comprising the above-mentioned battery cell.

[0074] In a third aspect, an embodiment of the present application further provides an electrical device comprising the above-mentioned battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0076] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0077] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0078] FIG3 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0079] FIG4 is an exploded view of a battery cell provided in some embodiments of the present application;

[0080] FIG5 is a bottom view of a housing provided in some embodiments of the present application;

[0081] FIG6 is a cross-sectional view of a first wall portion provided in some embodiments of the present application;

[0082] FIG7 is an enlarged view of point B1 in FIG6 ;

[0083] FIG8 is a bottom view of a housing provided in some other embodiments of the present application;

[0084] FIG9 is a bottom view of a housing provided in some further embodiments of the present application;

[0085] FIG10 is a bottom view of a housing provided in some other embodiments of the present application;

[0086] FIG11 is a bottom view of a housing provided in yet other embodiments of the present application;

[0087] FIG12 is a schematic diagram of the first wall portion observed along the length direction after the first groove is cracked;

[0088] FIG13 is a bottom view of a housing provided in yet other embodiments of the present application;

[0089] FIG14 is a bottom view of a housing provided in yet other embodiments of the present application;

[0090] FIG15 is a bottom view of a housing provided in some other embodiments of the present application;

[0091] FIG16 is a bottom view of a housing provided in yet other embodiments of the present application;

[0092] FIG17 is a bottom view of a housing provided in some other embodiments of the present application;

[0093] FIG18 is a cross-sectional view taken along the Q1-Q1 direction in FIG17 ;

[0094] FIG19 is an enlarged view of point B2 in FIG18 ;

[0095] FIG20 is an enlarged view of point B3 in FIG18 ;

[0096] FIG21 is a bottom view of a housing provided in some further embodiments of the present application;

[0097] FIG22 is a bottom view of a housing provided in some other embodiments of the present application;

[0098] FIG23 is a cross-sectional view taken along line Q2-Q2 in FIG22;

[0099] FIG24 is an enlarged view of point B4 in FIG23;

[0100] FIG25 is a cross-sectional view taken along line Q3-Q3 in FIG22;

[0101] FIG26 is an enlarged view of point B5 in FIG23;

[0102] FIG27 is an enlarged view of point B6 in FIG23 .

[0103] Icons: 1000-vehicle; 100-battery; 10-box; 11-first box body; 12-second box body; 20-battery cell; 21-housing; 211-first wall; 2111-first surface; 2112-second surface; 212-housing; 2121-opening; 2122-second wall; 2123-third wall; 2124-fourth wall; 2125-fifth wall; 2126-first chamfered surface; 2127-second chamfered surface; 2128-third chamfered surface; 2129-fourth chamfered surface; 213-end cover; 22-pressure relief component; 221-first groove; 2211-first weak portion; 2211a-first weak section; 2212-first groove section; 2213-second groove section ;2214-third slot section;2215-fourth slot section;222-second groove;2221-second weak portion;221a-first sub-slot;221a1-first section;221a2-second section;221a3-third section;221b-second sub-slot;221b1-fourth section;221b2-fifth section;221b3-sixth section;221c-third sub-slot;221c1-seventh section;221c2-eighth section;221c3-ninth section;23-electrode assembly;231-ear;24-electrode terminal;25-current collecting member;200-controller;300-motor;X-thickness direction of the first wall portion;Y-width direction of the first wall portion;Z-length direction of the first wall portion;P-predetermined pressure relief area. DETAILED DESCRIPTION

[0104] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0105] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0106] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0107] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0108] In the description of the embodiments of the present application, it should be noted that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are merely for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present application. In addition, the terms "first," "second," "third," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0109] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0110] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0111] The term "plurality" used in this application refers to two or more (including two).

[0112] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0113] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0114] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0115] 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.

[0116] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

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

[0118] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.

[0119] In some embodiments, a positive electrode may utilize a metal foam. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or the like. When a metal foam is used as the positive electrode, the surface of the metal foam may or may not include a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled or / and deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0120] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0121] As an example, the negative electrode current collector may be a metal foil, a metal foam, or a composite current collector. For example, as the metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. may be used. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, etc. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0122] 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.

[0123] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0124] As an example, the negative electrode active material may adopt the negative electrode active material for the battery cell 20 that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0125] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0126] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0127] In some embodiments, the separator is a separator membrane. There are many types of separator membranes, and any known separator membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0128] As an example, the separator can be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. In the case of a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0129] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0130] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel, or solid. Liquid electrolytes include an electrolyte salt and a solvent.

[0131] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0132] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent may also be an ether solvent. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0133] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0134] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0135] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, or the like.

[0136] As an example, the inorganic solid electrolyte may include an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0137] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0138] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0139] In some embodiments, the electrode assembly is a laminate structure.

[0140] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0141] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0142] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0143] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0144] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0145] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0146] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0147] In some embodiments, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0148] As an example, the battery cells may be cylindrical, prismatic, soft-pack or other shaped battery cells. Prismatic battery cells include but are not limited to square-shell, blade-shaped, and polygonal batteries, such as hexagonal batteries.

[0149] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0150] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0151] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0152] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body 10 can become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0153] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0154] Batteries, with their outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide adaptability, and low self-discharge coefficient, are a vital component of today's new energy development. The development of battery technology requires simultaneous consideration of multiple design factors, including performance parameters such as energy density, cycle life, discharge capacity, and charge / discharge rate. Furthermore, battery reliability must be considered.

[0155] In battery technology, for typical battery cells, to reduce the risk of explosion, fire, and other issues, a pressure relief component can be installed on the battery cell to release the internal pressure of the battery cell through the pressure relief component, thereby reducing the risk of explosion, fire, and other issues in the battery cell and improving the reliability of the battery cell. In related art, the pressure relief component is typically formed on the housing using an integral molding process, that is, integrated into the battery cell housing, or connected to the wall of the housing through welding, clamping, etc., so that when the internal pressure or temperature of the battery cell reaches a threshold, the pressure relief component can be activated and opened to release the internal pressure of the battery cell. However, battery cells are prone to expansion during use or charging and discharging. The expansion force generated by the battery cell acts on the pressure relief component, causing the pressure relief component to be extremely prone to stretching and deformation, resulting in strain and large strain amplitude in the pressure relief component. This reduces the structural strength of the pressure relief component of the battery cell, resulting in poor operational stability of the pressure relief component, and is prone to premature activation or fatigue cracking during use, which is not conducive to improving the service life and reliability of the battery cell.

[0156] Based on the above considerations, in order to alleviate the problem of premature actuation of pressure relief or fatigue cracking of the pressure relief component of the battery cell during use, an embodiment of the present application provides a battery cell, the battery cell including a shell and a pressure relief component; the shell includes a first wall portion, and in the thickness direction of the first wall portion, the first wall portion has a first surface and a second surface arranged opposite to each other; the pressure relief component is arranged on the first wall portion, and the pressure relief component is provided with a first groove, the first groove is recessed from the first surface toward the direction close to the second surface, and the first groove defines at least one predetermined pressure relief area, and the pressure relief component is configured to be able to crack along at least part of the first groove when the battery cell is depressurized; wherein the sum S1 of the areas of all predetermined pressure relief areas is 0.03 times to 0.3 times the area S2 of the first surface.

[0157] The first wall of the housing is provided with a pressure relief component, which includes a first weakened portion that is capable of rupturing when the battery cell releases pressure to release the pressure within the battery cell, thereby reducing the risk of explosion, fire, and other problems caused by excessive internal pressure in the battery cell. By setting the sum of the areas S1 of all predetermined pressure relief zones to 0.03 to 0.3 times the area S2 of the first surface provided with the first groove, that is, setting the ratio of the sum of the areas S1 of all predetermined pressure relief zones to the area S2 of the first surface provided with the first groove to 0.03 to 0.3, the relative sizes of the sum of the areas S1 of all predetermined pressure relief zones to the area S2 of the first surface provided with the first groove are more reasonably set. Setting the ratio to be greater than or equal to 0.03 can alleviate the problem of insufficient area of ​​the predetermined pressure relief zones and the phenomenon that the pressure relief component requires an excessively high burst pressure when releasing pressure from the battery cell due to excessive pressure bearing capacity of the bottom wall of the first groove. This can thereby reduce the risk of bursting, explosion, or fire of the battery cell housing caused by untimely pressure relief from the pressure relief component, thereby effectively improving the reliability of the battery cell. The expansion force generated by the expansion of the battery cell during use will cause the first wall portion to deform. Setting the ratio to less than or equal to 0.3 can alleviate the problem of the first wall portion being easily deformed due to the reduced strength and rigidity of the predetermined pressure relief area being too large relative to the first surface area. It can also reduce the concentration of stress on the bottom wall of the first groove when the expansion force generated by the expansion of the battery cell during use acts on the pressure relief component, and enable the predetermined pressure relief area to absorb a portion of the expansion force, thereby effectively alleviating the occurrence of tensile deformation and other phenomena on the bottom wall of the first groove of the pressure relief component, thereby reducing the strain and strain amplitude of the bottom wall of the first groove of the pressure relief component, that is, reducing the deformation of the bottom wall of the first groove, and thereby alleviating the phenomenon of the structural strength of the bottom wall of the first groove of the pressure relief component being reduced due to excessive strain and strain amplitude, thereby reducing the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component in the corresponding area of ​​the first groove after long-term use of the battery cell. This improves the stability of the pressure relief component in use and is conducive to improving the service life and reliability of the battery cell.

[0158] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical equipment such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and batteries disclosed in this application can be used to construct such electrical equipment. This can help alleviate issues such as premature activation of pressure relief components of the battery cells or fatigue cracking during use, thereby improving the reliability and service life of the battery cells.

[0159] The embodiments of the present application provide an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0160] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device in an embodiment of the present application.

[0161] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000. The battery 100 can be arranged at the bottom of the vehicle 1000, or at the head of the vehicle 1000, or at the tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can be used as an operating power source or a power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0162] In some embodiments of the present application, the battery 100 can not only serve as the operating power source or usage power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0163] 2 and 3 , FIG2 is an exploded view of a battery 100 according to some embodiments of the present invention, and FIG3 is a schematic structural diagram of a battery cell 20 according to some embodiments of the present invention. The battery 100 includes a housing 10 and a battery cell 20 , wherein the battery cell 20 is accommodated in the housing 10 .

[0164] The housing 10 is used to provide assembly space for the battery cells 20 and can adopt a variety of structures. In some embodiments, the housing 10 can include a first housing body 11 and a second housing body 12. The first housing body 11 and the second housing body 12 cover each other, and the first housing body 11 and the second housing body 12 jointly define an assembly space for accommodating the battery cells 20. The second housing body 12 can be a hollow structure with one end open, and the first housing body 11 can be a plate-like structure. The first housing body 11 covers the open side of the second housing body 12, so that the first housing body 11 and the second housing body 12 jointly define the assembly space. The first housing body 11 and the second housing body 12 can also be hollow structures with one end open, and the open side of the first housing body 11 covers the open side of the second housing body 12.

[0165] Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder, a cuboid or a cube, etc. For example, in FIG2 , the box body 10 is in the shape of a cuboid.

[0166] In the battery 100, there can be one or more battery cells 20 disposed within the housing 10. When there are multiple battery cells 20 disposed within the housing 10, the multiple battery cells 20 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel configurations within the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery 100 can be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid configuration to form a battery module, which is then further connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed within the housing 10.

[0167] In some embodiments, the battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, which is used to connect the multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20 .

[0168] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be a rectangular parallelepiped, a cylinder, a prism, or other shapes. For example, in FIG3 , the battery cell 20 is a rectangular parallelepiped.

[0169] In some embodiments, as shown in Figures 3 to 7, the battery cell 20 includes a shell 21 and a pressure relief component 22; the shell 21 includes a first wall portion 211; the pressure relief component 22 is arranged on the first wall portion 211, and along the thickness direction X of the first wall portion, the first wall portion 211 has a first surface 2111 and a second surface 2112 arranged opposite to each other, and the pressure relief component 22 is provided with a first groove 221, and the first groove 221 is recessed from the first surface 2111 toward the direction close to the second surface 2112, and the first groove 221 defines at least one predetermined pressure relief area P, and the pressure relief component 22 is configured to be able to split along at least part of the first groove 221 when the battery cell 20 is depressurized; wherein, the sum S1 of the areas of all predetermined pressure relief areas P is 0.03 times to 0.3 times the area S2 of the first surface 2111.

[0170] 4 , the battery cell 20 may further include an electrode assembly 23, which is housed in the outer shell 21. The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. The structure of the electrode assembly 23 may be various. For example, the electrode assembly 23 may be a wound structure formed by winding a positive electrode sheet, an isolating member, and a negative electrode sheet, or a stacked structure formed by stacking a positive electrode sheet, an isolating member, and a negative electrode sheet.

[0171] Illustratively, the separator is an isolation membrane, and a main material of the isolation membrane may be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0172] The battery cell 20 may include one electrode assembly 23 or multiple electrode assemblies 23. In Figure 4, the battery cell 20 includes two electrode assemblies 23, which are stacked along the thickness of the electrode assemblies 23. The stacking direction of the two electrode assemblies 23 may be the thickness direction of the battery cell 20. Of course, in other embodiments, the number of electrode assemblies 23 included in the battery cell 20 may also be three, four, five, etc.

[0173] In some embodiments, the battery cell 20 further includes an electrolyte contained in the housing 21. The electrolyte may be an electrolytic solution.

[0174] In some embodiments, the housing 21 may include a shell 212 and an end cover 213, and a accommodating cavity is formed inside the shell 212, which is used to accommodate the electrode assembly 23, and the accommodating cavity has at least one opening 2121. That is, the shell 212 is a hollow structure with at least one end opening 2121, and the end cover 213 covers the opening 2121 of the shell 212 and forms a sealed connection to form an enclosed space for accommodating the electrode assembly 23 and the electrolyte.

[0175] The first wall portion 211 provided with the pressure relief component 22 may be the end cover 213 of the outer shell 21, or may be a wall portion of the shell 212 of the outer shell 21. For example, in Figures 3 and 4, the first wall portion 211 is the end cover 213. Of course, the structure of the battery cell 20 is not limited thereto. In other embodiments, the first wall portion 211 may also be a wall portion of the shell 212 and the end cover 213 arranged opposite each other, that is, the bottom wall of the shell 212. The first wall portion 211 may also be a side wall of the shell 212 and the end cover 213 that are adjacent to and connected to each other. The side wall may be a wall arranged around the end cover 213 and forming the opening 2121.

[0176] When assembling the battery cell 20 , the electrode assembly 23 may be placed in the housing 212 first, and the housing 212 may be filled with electrolyte. The end cap 213 may then be placed on the opening 2121 of the housing 212 to complete the assembly of the battery cell 20 .

[0177] The shell 212 can be in various shapes, such as a cylinder, a cuboid or a prismatic structure. The shape of the shell 212 can be determined according to the specific shape of the electrode assembly 23. For example, if the electrode assembly 23 is a cylindrical structure, a shell 212 with a cylindrical structure can be selected; if the electrode assembly 23 is a cuboid structure, a shell 212 with a cuboid structure can be selected. Of course, the structure of the end cover 213 can also be various, for example, the end cover 213 is a plate-like structure or a hollow structure with one end open. For example, in Figures 3 and 4, the shell 212 is a cuboid structure, the length direction Z of the first wall portion is the length direction of the battery cell 20, the width direction Y of the first wall portion is the thickness direction of the battery cell 20, and the thickness direction X of the first wall portion is the height direction of the battery cell 20.

[0178] Of course, it is understandable that the shell 21 is not limited to the above structure. The shell 21 may also be other structures. For example, the shell 21 may include a shell body 212 and two end covers 213. The shell body 212 is a hollow structure with openings 2121 formed at both opposite ends. One end cover 213 corresponds to an opening 2121 of the shell body 212 and forms a sealed connection to form an enclosed space for accommodating the electrode assembly 23 and the electrolyte. That is, the shell body 212 has openings 2121 on both opposite sides, and the two end covers 213 are respectively covered on both sides of the shell body 212 to close the corresponding openings 2121.

[0179] The housing 21 may be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy.

[0180] In some embodiments, the battery cell 20 further includes an electrode terminal 24 . The electrode terminal 24 may be insulated and mounted on the housing 21 , and the electrode terminal 24 is electrically connected to the electrode assembly 23 to output or input electrical energy to the battery cell 20 .

[0181] It should be noted that the electrode terminal 24 is insulated and mounted on the housing 21 , that is, no electrical connection is formed between the electrode terminal 24 and the housing 21 .

[0182] The battery cell 20 may include one or two electrode terminals 24. For example, as shown in Figures 3 and 4 , the battery cell 20 includes two electrode terminals 24, which are spaced apart along the lengthwise direction Z of the first wall portion. Each electrode assembly 23 has two tabs 231, which are spaced apart along the lengthwise direction Y of the wall portion. The two tabs 231 have opposite polarities, and the two electrode terminals 24 are electrically connected to the two tabs 231 of the electrode assembly 23, respectively, with opposite polarities, to enable input or output of the positive and negative electrodes of the battery cell 20.

[0183] It should be noted that one tab 231 of the electrode assembly 23 can be a component formed by stacking and connecting areas on the positive electrode sheet that are not coated with the positive electrode active material layer, forming a positive tab 231, and the other tab 231 can be a component formed by stacking and connecting areas on the negative electrode sheet that are not coated with the negative electrode active material layer, forming a negative tab 231.

[0184] Exemplarily, the electrode terminal 24 may be made of a variety of materials. For example, the electrode terminal 24 may be made of copper, iron, aluminum, steel, or aluminum alloy.

[0185] There are various locations where the electrode terminals 24 can be mounted on the outer shell 21. For example, in Figures 3 and 4, both electrode terminals 24 are mounted on the end cap 213 of the outer shell 21. Of course, the structure of the battery cell 20 is not limited to this. In the embodiment where the battery cell 20 includes two electrode terminals 24, both electrode terminals 24 can also be mounted on the shell 212 of the outer shell 21. Similarly, one electrode terminal 24 can be mounted on the shell 212 of the outer shell 21, and the other electrode terminal 24 can be mounted on the end cap 213 of the outer shell 21.

[0186] In some embodiments, as shown in Figure 4, the battery cell 20 may also include two current collecting components 25, both of which are arranged in the outer shell 21 and are spaced apart along the length direction Z of the first wall portion. Each current collecting component 25 is used to connect an electrode terminal 24 and a plurality of electrode assemblies 23 with the same polarity in the electrode lugs 231 to achieve electrical connection between the electrode terminal 24 and the electrode assembly 23, which is beneficial to reduce the difficulty of assembly between the electrode lug 231 and the electrode terminal 24.

[0187] Exemplarily, the material of the current collecting member 25 may be various, for example, the material of the current collecting member 25 may be copper, iron, aluminum, steel or aluminum alloy.

[0188] In the embodiment of the present application, the pressure relief component 22 serves to relieve pressure in the battery cell 20 , and is used to release the pressure inside the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value.

[0189] The pressure relief component 22 may have various structures. For example, the pressure relief component 22 may be a separate structure from the first wall portion 211 of the housing 21, or the pressure relief component 22 may be an integral structure with the first wall portion 211 of the housing 21. When the pressure relief component 22 and the first wall portion 211 of the housing 21 are separate structures, that is, the first wall portion 211 of the housing 21 is provided with a pressure relief hole (not shown in the figure) for mounting the pressure relief component 22. The pressure relief component 22 is connected to the first wall portion 211 and covers the pressure relief hole. The pressure relief component 22 and the first wall portion 211 may be connected in various ways, such as welding or clamping. When the pressure relief component 22 and the first wall portion 211 of the outer shell 21 are an integrally formed structure, the pressure relief component 22 is a wall portion of the outer shell 21, that is, the pressure relief component 22 is integrated on the first wall portion 211 and forms a wall of the outer shell 21. Correspondingly, the pressure relief component 22 is a weak structure formed on the first wall portion 211 for cracking when the battery cell 20 releases pressure.

[0190] Exemplarily, the pressure relief component 22 and the first wall portion 211 are an integrally formed structure, that is, the pressure relief component 22 is the first wall portion 211, and the first weak portion 2211 formed by the bottom wall of the first groove 221 and the predetermined pressure relief area P are both formed on the first wall portion 211.

[0191] The first surface 2111 and the second surface 2112 are two opposing surfaces of the first wall portion 211 in the thickness direction X. The first groove 221 is recessed from the first surface 2111 toward the second surface 2112. In the embodiment where the first wall portion 211 and the pressure relief component 22 are integrally formed, it is understood that the first groove 221 is provided on the first surface 2111.

[0192] The pressure relief component 22 forms a first weak portion 2211 at a position corresponding to the first groove 221, that is, the bottom wall of the first groove 221 is the first weak portion 2211. The bottom wall of the first groove 221 is a part of the pressure relief component 22. The bottom wall of the first groove 221 is the area of ​​the pressure relief component 22 with the smallest thickness in the thickness direction X of the first wall portion. Therefore, the bottom wall of the first groove 221 is more likely to rupture due to the increase in air pressure inside the battery cell 20 than other areas of the pressure relief component 22. The extension trajectory of the first groove 221 is the rupture trajectory of the pressure relief component 22. The pressure relief component 22 can open the predetermined pressure relief area P after at least part of the bottom wall of the first groove 221 is ruptured, so that the battery cell 20 can release the pressure inside the battery cell 20 from the predetermined pressure relief area P.

[0193] The first groove 221 defines at least one predetermined pressure relief area P, that is, the predetermined pressure relief area P is a portion of the pressure relief component 22. The first groove 221 can define one predetermined pressure relief area P. The first groove 221 can also define multiple predetermined pressure relief areas P, such as two predetermined pressure relief areas P, three predetermined pressure relief areas P, four predetermined pressure relief areas P, etc.

[0194] Depending on the structural shape of the first groove 221, the predetermined pressure relief zone P is formed in different ways. For example, in some embodiments, the first groove 221 forms a closed structure along the extension direction of the first groove 221, and the space enclosed by the first groove 221 is the predetermined pressure relief zone P. For example, as shown in Figures 3-5, the extension trajectory of the first groove 221 is an ellipse, and the first groove 221 defines an elliptical predetermined pressure relief zone P. In this embodiment, the sum S1 of the areas of all predetermined pressure relief zones P is the area of ​​the region enclosed by the outer contour of the first groove 221. The outer contour of the first groove 221 is the contour of the edge of the first groove 221 in the width direction of the first groove 221 that is closest to the first wall portion 211.

[0195] In other embodiments, along the extension direction of the first groove 221, the first groove 221 is a non-enclosed structure, and the predetermined pressure relief area P is defined by the first groove 221 and the line connecting the ends of the first groove 221. It should be noted that the line connecting the ends of the first groove 221 is a virtual line. For example, as shown in Figure 8, along the extension direction of the first groove 221, the first groove 221 is V-shaped, and the predetermined pressure relief area P is defined by the V-shaped first groove 221 and the line connecting the two ends of the V-shaped first groove 221. For example, as shown in Figure 9, along the extension direction of the first groove 221, the first groove 221 is U-shaped, and the predetermined pressure relief area P is defined by the U-shaped first groove 221 and the line connecting the two ends of the U-shaped first groove 221. In this case, the sum S1 of the areas of all predetermined pressure relief areas P is the area of ​​the area enclosed by the outer contour of the first groove 221 and the line connecting the ends of the first groove 221. The dotted line showing the position of the pressure relief component 22 in FIG8 and FIG9 is a line connecting the ends of the first groove 221 .

[0196] The dashed lines parallel to the second groove 222 in Figures 11-16 are lines connecting the ends of the first groove section 2212 and the third groove section 2214 of the first groove 221 in the direction of their extension. Together with the first groove 221, these two dashed lines form two predetermined pressure relief areas P. The dashed lines in Figure 15 are lines connecting the ends of the first groove section 2212 and the third groove section 2214 of the first groove 221 in the direction of their extension. Together with the first groove 221, these two dashed lines form two predetermined pressure relief areas P.

[0197] The dotted line parallel to the second groove 222 in FIG17 is a line connecting the ends of the first groove section 2212 and the third groove section 2214 of the first groove 221 in their extension direction. The two dotted lines and the first groove 221 together form two predetermined pressure relief areas P.

[0198] The first groove 221 includes at least one groove segment. The bottom wall of each groove segment of the first groove 221 forms a corresponding first weak section 2211a. The first weak sections 2211a formed by each groove segment collectively form a first weak portion 2211. It should be noted that each groove segment of the first groove 221 extends along a smooth trajectory, such as a straight line or an arc. The first groove 221 may have one or more groove segments. If the first groove 221 has a straight line, an arc, or an annular structure, the first groove 221 includes only one groove segment, and the first weak portion 2211 formed by the bottom wall of the first groove 221 includes one first weak section 2211a. If the first groove 221 has a "V"-shaped structure, a "U"-shaped structure, or an "H"-shaped structure, the first groove 221 includes multiple groove segments, and the first weak portion 2211 formed by the bottom wall of the first groove 221 includes multiple first weak sections 2211a. For example, in Figures 3-5 , the pressure relief component 22 is provided with a first groove 221, which is an annular groove. The first groove 221 includes a groove segment, and the bottom wall of the first groove 221 forms a first weak portion 2211 including a first weak section 2211a. For another example, as shown in Figure 8 , the pressure relief component 22 is provided with a first groove 221, which includes a first groove segment 2212 and a second groove segment 2213 connected to form a V-shaped first groove 221. The bottom walls of the first groove segment 2212 and the second groove segment 2213 each form a first weak section 2211a. The first weak portion 2211 formed by the bottom wall of the first groove 221 includes two first weak sections 2211a.

[0199] As shown in FIG9 , the pressure relief component 22 is provided with a first groove 221. The bottom wall of the first groove 221 forms a first weak portion 2211. The first groove 221 includes a first groove section 2212, a second groove section 2213, and a third groove section 2214 connected to each other, forming a U-shaped first groove 221. The first groove section 2212 and the third groove section 2214 are arranged opposite each other, and the second groove section 2213 connects to the first groove section 2212. The bottom walls of the first groove section 2212, the second groove section 2213, and the third groove section 2214 each form a first weak portion 2211a. The first groove 221 includes three groove sections, and the first weak portion 2211 formed by the bottom wall of the first groove 221 includes three first weak portions 2211a.

[0200] For another example, in FIG10 , the pressure relief component 22 is provided with a first groove 221, the bottom wall of the first groove 221 forms a first weak portion 2211, the first groove 221 includes a first groove section 2212, a second groove section 2213, a third groove section 2214 and a fourth groove section 2215, the first groove section 2212 and the third groove section 2214 are arranged opposite to each other, the second groove section 2213 connects the first groove section 2212 and the third groove section 2214, the fourth groove section 2215 is located at the first groove section 2212 and the third groove section 2214, and the fourth groove section 2215 is located at the first groove section 2212. Between the first groove section 2212 and the third groove section 2214, and the fourth groove section 2215 is connected to the second groove section 2213, the groove bottom wall of the first groove section 2212, the groove bottom wall of the second groove section 2213, the groove bottom wall of the third groove section 2214 and the groove bottom wall of the fourth groove section 2215 all form a first weak section 2211a, the first groove 221 includes four groove sections, and the first weak portion 2211 formed by the groove bottom wall of the first groove 221 includes four first weak sections 2211a.

[0201] The sum S1 of the areas of all the predetermined pressure relief areas P is set to 0.03 to 0.3 times the area S2 of the first surface 2111 provided with the first groove 221, that is, the ratio S1 of the sum of the areas of all the predetermined pressure relief areas P to the area S2 of the first surface 2111 provided with the first groove 221 is set to 0.03 to 0.3. Exemplarily, the ratio S1 of the sum S1 of the areas of all the predetermined pressure relief areas P to the area S2 of the first surface 2111, that is, S1 / S2 can be: 0.03, 0.04, 0.05, 0.0588, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, etc.

[0202] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to Examples 1-7 and Comparative Examples 1-4. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually merely illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0203] Example 1

[0204] 1. Preparation of Battery Cell 20

[0205] 1) Preparation of positive electrode

[0206] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are prepared into positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the solid content of LiNi 0.7 Co 0.1 Mn 0.1 The mass ratio of O2, Super P and PVDF is 8:1:1. The positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil and dried at 85°C and then cold pressed. Then, it is trimmed, cut and striped, and dried under vacuum conditions at 85°C for 4 hours to make the positive electrode sheet.

[0207] 2) Preparation of negative electrode sheet

[0208] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene-butadiene rubber (SBR) were mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry was 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC, and adhesive styrene-butadiene rubber (SBR) in the solid components was 88:7:3:2. The negative electrode slurry was coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C. Then, it was cold pressed, trimmed, cut into pieces, and slit, and then dried under vacuum conditions at 120°C for 12 hours to prepare a negative electrode sheet.

[0209] 3) Preparation of electrolyte

[0210] In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), the fully dried electrolyte salt LiPF6 was dissolved in a mixed solvent (the mixed solvent included ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 50:50), and after mixing evenly, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0211] 4) Isolation parts

[0212] A 16 μm polyethylene film was used as a separator.

[0213] 5) Preparation of battery cell 20

[0214] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator positioned between the positive and negative electrode sheets to separate them. The electrode assembly 23 is then wound and placed within an aluminum casing 21. The prepared electrolyte is injected into the dried casing 21. The battery cell 20 is then packaged, left to rest, formed, shaped, and capacity tested, completing the process. The casing 21 of the battery cell 20 is a rectangular parallelepiped structure. The housing 212 of the casing 21 has an opening 2121 formed at one end. The wall of the casing 212 opposite the end cap 213 is a first wall 211, which is a rectangular wall. A pressure relief component 22 is provided on the first wall 211 of the casing 21. The first wall 211 and the pressure relief component 22 are integrally formed. The pressure relief component 22 is provided with a first groove 221, so that the bottom wall of the first groove 221 forms a first weak portion 2211. The first groove 221 is an H-shaped structure and a three-level notch groove. The first groove 221 is provided on the outer surface of the first wall portion 211. Among them, the sum S1 of the areas of all the predetermined pressure relief areas P of the pressure relief component 22 of the battery cell 20 of Example 1 is 420mm 2 , the area S2 of the first surface 2111 is 14000mm 2 .

[0215] The preparation methods of the battery cells 20 of Examples 2-7 and Comparative Examples 1-4 are the same as that of Example 1, except that the sum S1 of the areas of all the predetermined pressure relief areas P and the area S2 of the first surface 2111 are different.

[0216] By performing fatigue tests on the battery cells 20 in Examples 1-7 and Comparative Examples 1-4, the number of fatigue cycles of the battery cells 20 during long-term use is obtained, and by performing thermal runaway tests on the battery cells 20, the breath holding time of the battery cells 20 during thermal runaway is obtained, so as to evaluate the reliability of the battery cells 20, as shown in Table 1.

[0217] The fatigue times of the battery cell 20 are measured as follows:

[0218] 1) Prepare a special test fixture. Specifically, the fixture consists of three 10mm steel plates (first steel plate, second steel plate, and third steel plate). Each steel plate can completely cover the large surface of the battery cell 20 (the large surface of the battery cell 20 refers to the outer surface of the shell 212 perpendicular to the width direction Y along the first wall). The first steel plate and the third steel plate are located at both ends of the fixture and are fixed by bolts. The second steel plate is located between the first steel plate and the third steel plate, and the second steel plate is constrained by a guide rail. The second steel plate can only move horizontally in a direction perpendicular to the plane of the steel plate.

[0219] 2) The battery cell 20 is installed between the first steel plate and the second steel plate, and a support structure is placed between the large surface of one side of the battery cell 20 and the first steel plate, and the large surface of the other side and the second steel plate. The support structure can be an insulation pad or a water-cooling plate (consistent with the material / structure between two adjacent battery cells 20 in the actual battery 100). The support structure can be compressed to provide expansion space for the battery cell 20 during the charge and discharge cycle aging process; the large surface of the battery cell 20 is in contact with the support structure, the first steel plate is in contact with the corresponding support structure, the second steel plate is in contact with the corresponding support structure, and a pressure sensor is provided between the second steel plate and the third steel plate.

[0220] 3) Adjust the position of the second steel plate by pre-tightening the bolts, observe the pressure sensor, and make the initial extrusion force on the battery cell 20 2000N, and connect the two electrical connection parts (positive electrode terminal 24 and negative electrode terminal 24) of the battery cell 20 to the charging and discharging equipment.

[0221] 4) Place the battery cell 20 and the fixture in a constant temperature environment of 25±2°C, and start the test after the battery cell 20 reaches temperature equilibrium.

[0222] 5) The test steps are carried out in accordance with Section 6.4 "Standard Cycle Life" of GBT31484-2015 Cycle Life Requirements and Test Methods for Power Batteries for Electric Vehicles, and the test cycle end condition is changed to "stop testing until the first groove 221 of the pressure relief component 22 is damaged."

[0223] Specifically, test according to the following steps:

[0224] a) Discharge to 2.8V with a current of 1I1(A);

[0225] b) Leave it for no less than 30 minutes;

[0226] c) Charge in accordance with the method 6.1.1.3 of GBT31484-2015 Cycle Life Requirements and Test Methods for Power Batteries for Electric Vehicles;

[0227] d) Leave it for no less than 30 minutes;

[0228] e) Discharge to 2.8V at a current of 1I1(A);

[0229] f) Repeat steps b) to e) until the first groove 221 of the pressure relief component 22 is damaged and the test is stopped.

[0230] Specifically, during the test, the area of ​​the pressure relief member 22 of the battery cell 20, located around the first groove 221, is continuously observed until the pressure relief member breaks and leaks. The number of cycles is recorded as the fatigue cycle count of the battery cell 20. The greater the fatigue cycle count of the battery cell 20, the lower the probability of valve opening and leakage due to gas production during long-term use, and the longer the battery cell 20's service life.

[0231] The thermal runaway test method for battery cell 20 is as follows:

[0232] 1. Select the heating plate according to the size of the battery cell 20. The size of the heating plate should cover as much of the battery cell 20 as possible (coverage area ≥ 60%);

[0233] 2. Charge the battery cell 20 to 100% SOC before testing and ensure that the temperature of the battery cell 20 is 25±5℃;

[0234] 3. Sensor layout:

[0235] 1) Arrangement of temperature-sensing wires: A layer of Teflon is applied to the center areas of the two large surfaces of the battery cell 20, and a temperature-sensing wire is arranged above the Teflon, followed by another layer of Teflon.

[0236] 2) Layout of voltage sampling lines: A layer of Teflon is applied to the positive electrode terminal, negative electrode terminal and housing 21 of the battery cell 20, and a voltage sampling line is arranged above the Teflon, followed by another layer of Teflon.

[0237] 3) Air pipe arrangement: Drill a hole in the first wall 211 of the housing 21 of the battery cell 20. The hole is located at the center between the edge of the first groove 221 and the side surface of the housing 212 (the outer surface of the wall adjacent to the first wall 211 along the length direction Z of the housing 212). Insert the air pipe into the hole and seal it. Connect the air pipe to the air pressure sensor.

[0238] 4) Connect the temperature sensing wire, voltage sampling wire and air pressure sensor to the data acquisition instrument to collect and analyze data in real time. The acquisition frequency of the data acquisition instrument is ≤0.1s;

[0239] 4. Assemble the fixture so that it completely covers the large surface of the battery cell 20, with a clamping force of 3000N. Note: The arrangement order of the fixture, heating plate and battery cell 20 is: fixture + heating plate + battery cell 20 + fixture;

[0240] 5. Testing: Turn on the data acquisition instrument to collect temperature, voltage, and air pressure data, then turn on the heating plate at a power of 500W to heat the battery cell 20 until the battery cell 20 thermally runs away.

[0241] 6. Obtain the pressure holding time of the battery cell 20, determine the thermal runaway moment and valve opening moment based on the temperature, voltage, and air pressure data collected by the data acquisition instrument, and calculate the pressure holding time of the battery cell 20 based on the formula: pressure holding time = valve opening moment - thermal runaway moment.

[0242] Thermal runaway criteria: a) The triggering object generates a voltage drop exceeding 25% of the initial voltage; b) The temperature at the detection point reaches the manufacturer's maximum operating temperature; c) The temperature rise rate dT / dt at the detection point is ≥ 1°C / s and persists for more than 3 seconds. Thermal runaway is determined to have occurred when a) and c) or b) and c) occur, and the moment of thermal runaway is determined.

[0243] Valve opening time determination: When the air pressure drops by more than 25%, it can be determined that the valve is open (the first groove 221 is broken), and the moment when the air pressure begins to drop is the valve opening time.

[0244] By performing fatigue tests on the battery cells 20 in Examples 1-7 and Comparative Examples 1-4, the number of fatigue cycles of the battery cells 20 during long-term use is obtained, and by performing thermal runaway tests on the battery cells 20, the breath holding time of the battery cells 20 during thermal runaway is obtained, so as to evaluate the reliability of the battery cells 20, as shown in Table 1.

[0245] Table 1:

[0246] As shown in Table 1, as S1 / S2 gradually increases, the holding time of the battery cell 20 shortens. Specifically, as S1 / S2 gradually increases, the battery cell 20's timely pressure relief performance improves, and the probability of explosion and fire in the event of thermal runaway of the battery cell 20 is lower. As S1 / S2 gradually increases, the fatigue life of the battery cell 20 gradually decreases. Specifically, as S1 / S2 gradually increases, the likelihood of the battery cell 20 opening the valve and leaking fluid due to fatigue during long-term use increases.

[0247] In Table 1, when S1 / S2 is 0.01 and 0.02, the holding time of the battery cell 20 is 4.7s and 3.9s, respectively, which are much longer than the holding time when S1 / S2 is 0.03, 0.0588, 0.08, 0.1, 0.15, 0.25, 0.3, 0.4, and 0.5. That is, the holding time of the battery cell 20 during thermal runaway in Comparative Examples 1 and 2 is much longer than the holding time of the battery cell 20 in Examples 1 to 7, Comparative Examples 3, and 4. Therefore, when S1 / S2 is ≥ 0.03, the holding time of the battery cell 20 during thermal runaway is shorter, which can increase the possibility of timely pressure relief of the pressure relief component 22 of the battery cell 20, and reduce the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22.

[0248] In Table 1, when S1 / S2 is 0.4 and 0.5, the fatigue times of the battery cell 20 are 873 and 750 respectively, which are much smaller than the fatigue times when S1 / S2 is 0.01, 0.02, 0.03, 0.0588, 0.08, 0.1, 0.15, 0.25, and 0.3. That is, the fatigue times of the battery cell 20 in Comparative Examples 3 and 4 are much smaller than

[0249] The fatigue times of the battery cells 20 in Examples 1 to 7, Comparative Examples 1 and 2 are such that S1 / S2 ≤ 0.3. The fatigue times of the battery cells 20 are large, which results in a longer fatigue life of the battery cells 20, thereby reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 in the area corresponding to the first groove 221 after long-term use of the battery cells 20. Therefore, 0.03 ≤ S1 / S2 ≤ 0.3 can simultaneously reduce the risk of bursting, explosion, or fire in the outer shell 21 of the battery cells 20 due to untimely pressure relief of the pressure relief component 22, and reduce the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 in the area corresponding to the first groove 221 after long-term use of the battery cells 20, thereby improving the stability of the pressure relief component 22 and improving the service life and reliability of the battery cells 20.

[0250] In summary, by setting the sum S1 of the areas of all the predetermined pressure relief areas P to 0.03 to 0.3 times the area S2 of the first surface 2111 provided with the first groove 221, that is, the ratio of the sum S1 of the areas of all the predetermined pressure relief areas P to the area S2 of the first surface 2111 provided with the first groove 221 is set to 0.03 to 0.3, so that the relative size setting of the sum S1 of the areas of all the predetermined pressure relief areas P and the area S2 of the first surface 2111 provided with the first groove 221 is more reasonable. Setting the ratio to be greater than or equal to 0.03 can alleviate the problem of insufficient area of ​​the predetermined pressure relief areas P, so as to alleviate the phenomenon that the pressure bearing capacity of the bottom wall of the first groove 221 is too large, resulting in excessive bursting pressure required by the pressure relief component 22 when the battery cell 20 is relieved of pressure, thereby reducing the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, thereby effectively improving the reliability of the battery cell 20. The expansion force generated by the expansion of the battery cell 20 during use will cause the first wall portion 211 to deform. Setting the ratio to be less than or equal to 0.3 can alleviate the problem that the strength and rigidity of the first wall portion 211 are reduced and large deformation occurs easily due to the area of ​​the predetermined pressure relief area P being too large relative to the area of ​​the first surface 2111. It can also reduce the concentration of stress on the bottom wall of the first groove 221 when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22, and enable the predetermined pressure relief area P to absorb part of the expansion force, thereby effectively alleviating the pressure relief component 22. The bottom wall of the first groove 221 of the pressure relief component 22 undergoes tensile deformation and the like, so as to reduce the strain and strain amplitude of the bottom wall of the first groove 221 of the pressure relief component 22, that is, the deformation of the bottom wall of the first groove 221 can be reduced, thereby alleviating the phenomenon that the bottom wall of the first groove 221 of the pressure relief component 22 is reduced in structural strength due to excessive strain and strain amplitude, thereby reducing the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component 22 in the corresponding area of ​​the first groove 221 after long-term use of the battery cell 20, thereby improving the use stability of the pressure relief component 22, which is beneficial to improving the service life and reliability of the battery cell 20.

[0251] In some embodiments, 500 mm 2 ≤S1≤1300mm 2 .

[0252] For example, S1 may be 500 mm 2 , 600mm 2 , 630mm 2 、650mm 2 , 800mm 2 , 900mm 2 , 1000mm 2 , 1200mm2 , 1250mm 2 , 1300mm 2 wait.

[0253] Please continue to refer to Table 1. When S1≥500mm 2 The holding time of the battery cell 20 is 420mm compared to S1. 2 The holding time of the battery cell 20 is shorter, which can increase the possibility of timely pressure relief of the pressure relief component 22 of the battery cell 20, and reduce the risk of bursting, explosion, fire, etc. of the battery cell 20 shell 21 due to untimely pressure relief of the pressure relief component 22. 2 The fatigue times of the battery cell 20 at S1 is 1500 mm 2 , 1600mm 2 The fatigue times of the battery cell 20 are greater, so that the fatigue life of the battery cell 20 is longer, thereby further reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 in the corresponding area of ​​the first groove 221 after long-term use of the battery cell 20. 2 ≤S1≤1300mm 2 , which can reduce the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to the untimely pressure relief of the pressure relief component 22, and reduce the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 at the corresponding position of the first groove 221 of the battery cell 20 after long-term use, thereby improving the use stability of the pressure relief component 22 and improving the service life and reliability of the battery cell 20.

[0254] Therefore, by limiting the sum of the areas S1 of all the predetermined pressure relief zones P to 500 mm 2 Up to 1300mm 2 , the sum of the areas of all predetermined pressure relief zones P is set to be greater than or equal to 500mm 2 , can alleviate the problem of insufficient area of ​​the predetermined pressure relief area P, so as to alleviate the phenomenon that the pressure relief component 22 requires too much bursting pressure when the battery cell 20 is depressurized due to the excessive pressure bearing capacity of the bottom wall of the first groove 221, thereby reducing the risk of bursting, explosion, fire, etc. of the battery cell 20 shell 21 caused by the untimely pressure relief component 22, and further effectively improve the reliability of the battery cell 20. The sum of the areas of all predetermined pressure relief areas P is set to be less than or equal to 1300mm 2, which can alleviate the problem of the first wall portion 211 being easily deformed due to the reduced strength caused by the excessive area of ​​the predetermined pressure relief area P. It can also reduce the concentration of stress on the bottom wall of the first groove 221 when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22, and enable the predetermined pressure relief area P to absorb part of the expansion force, thereby effectively alleviating the phenomenon of tensile deformation and the like of the bottom wall of the first groove 221 of the pressure relief component 22, thereby reducing the strain and strain amplitude of the bottom wall of the first groove 221 of the pressure relief component 22, that is, reducing the deformation of the bottom wall of the first groove 221, thereby alleviating the phenomenon of the structural strength of the bottom wall of the first groove 221 of the pressure relief component 22 being reduced due to excessive strain and strain amplitude, thereby reducing the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component 22 in the corresponding area of ​​the first groove 221 after long-term use of the battery cell 20, thereby improving the stability of the pressure relief component 22 and facilitating the service life and reliability of the battery cell 20.

[0255] In some embodiments, 5000 mm 2 ≤S2≤8500mm 2 .

[0256] For example, S2 can be 5000mm 2 , 6000mm 2 、6500mm 2 , 7000mm 2 , 7500mm 2 , 8500mm 2 wait.

[0257] Please continue to refer to Table 1. When S2≥5000mm 2 The fatigue times of the battery cell 20 at S2 is 4300mm compared to S2. 2 The fatigue times of the battery cell 20 are greater, so that the battery cell 20 has a longer fatigue life, thereby further reducing the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 in the corresponding area of ​​the first groove 221 of the battery cell 20 after long-term use. 2 The holding time of the battery cell 20 is 14000mm compared to S2. 2 The holding time of the battery cell 20 is shorter, which can increase the possibility of timely pressure relief of the pressure relief component 22 of the battery cell 20 and reduce the risk of bursting, explosion, fire, etc. of the battery cell 20 shell 21 due to untimely pressure relief of the pressure relief component 22. Therefore, 5000mm 2 ≤S2≤8500mm 2, which can reduce the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to the untimely pressure relief of the pressure relief component 22, and reduce the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 at the corresponding position of the first groove 221 of the battery cell 20 after long-term use, thereby improving the use stability of the pressure relief component 22 and improving the service life and reliability of the battery cell 20.

[0258] Therefore, by setting the area S2 of the first surface 2111 where the first groove 221 is provided to 5000 mm 2 Up to 8500mm 2 , the area of ​​the first surface 2111 is set to be greater than or equal to 5000mm 2 , which can alleviate the problem of the first wall portion 211 being easily deformed due to the reduced strength of the first surface 2111 being too small, and can also reduce the concentration of stress on the bottom wall of the first groove 221 when the expansion force generated by the expansion of the battery cell 20 during use acts on the pressure relief component 22, and enable the predetermined pressure relief area P to absorb a portion of the expansion force, thereby effectively alleviating the phenomenon of tensile deformation and the like of the bottom wall of the first groove 221 of the pressure relief component 22, thereby reducing the strain and strain amplitude of the bottom wall of the first groove 221 of the pressure relief component 22, that is, reducing the deformation of the bottom wall of the first groove 221, and further alleviating the phenomenon of the structural strength of the bottom wall of the first groove 221 of the pressure relief component 22 being reduced due to excessive strain and strain amplitude, thereby reducing the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component 22 in the corresponding area of ​​the first groove 221 after long-term use of the battery cell 20, thereby improving the stability of the pressure relief component 22 and facilitating the service life and reliability of the battery cell 20. The area of ​​the first surface 2111 is set to be less than or equal to 8500mm 2 , which can alleviate the problem that the first surface 2111 is too small, resulting in the first wall portion 211 having greater strength and rigidity and being able to withstand greater pressure and difficult to deform, and alleviate the phenomenon that the pressure bearing capacity of the bottom wall of the first groove 221 is too large, resulting in the pressure relief component 22 requiring too large an explosion pressure when the battery cell 20 is relieved of pressure, thereby reducing the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, and further effectively improving the reliability of the battery cell 20.

[0259] In some embodiments, the first wall portion 211 is a rectangular wall portion; along the width direction Y of the first wall portion, the size of the first surface 2111 is c; along the length direction Z of the first wall portion, the size of the first surface 2111 is d, S2=c*d; wherein, 55mm≤c≤85mm, 100mm≤d≤260mm.

[0260] c is the dimension of the first surface 2111 along the width direction Y of the first wall portion. d is the dimension of the first surface 2111 along the length direction Z of the first wall portion.

[0261] Since it is difficult to determine the boundaries of the first wall portion 211 in its length direction and its width direction after the battery cell 20 is assembled and formed, in some embodiments, the distance c1 between the outer surface of the second wall portion 2122 and the outer surface of the third wall portion 2123 connected at both ends of the width direction Y of the first wall portion can be measured, and the distance between the outer surface of the second wall portion 2122 and the outer surface of the third wall portion 2123 can be equivalent to the dimension c of the first wall portion 211 in the width direction Y of the first wall portion, that is, c1 = c1. In some cases, the outer surface of the second wall portion 2122 and the surface of the first wall portion 211 facing away from the interior of the housing 212 (the first surface 2111) are connected by a first chamfered surface 2126, and the outer surface of the third wall portion 2123 and the surface of the first wall portion 211 facing away from the interior of the housing 212 (the first surface 2111) are connected by a second chamfered surface 2127. Along the width direction Y of the first wall portion, the dimension of the first chamfered surface 2126 is R1, and the dimension of the second chamfered surface 2127 is R2. The dimension c of the first surface 2111 is the distance between the outer surfaces of the second wall portion 2122 and the outer surfaces of the third wall portion 2123, minus the dimension of the first chamfered surface 2126 along the width direction Y of the first wall portion and minus the dimension of the second chamfered surface 2127 along the width direction Y of the first wall portion, i.e., c = c, - R1 - R2. The first chamfered surface 2126 and the second chamfered surface 2127 can be chamfered or rounded surfaces. In an embodiment where the first chamfered surface 2126 and the second chamfered surface 2127 are rounded surfaces, R1 may be the radius of the first chamfered surface 2126 , and R2 may be the radius of the second chamfered surface 2127 .

[0262] The distance d' between the outer surface of the fourth wall portion 2124 and the outer surface of the fifth wall portion 2125 connected at both ends of the length direction Z of the first wall portion can be measured, and the distance between the outer surface of the fourth wall portion 2124 and the outer surface of the fifth wall portion 2125 can be equivalent to the dimension d of the first wall portion 211 in the length direction Z of the first wall portion, that is, d=d'. In some cases, the outer surface of the fourth wall portion 2124 and the surface of the first wall portion 211 facing away from the interior of the housing 212 (first surface 2111) are connected by a third chamfered surface 2128, and the outer surface of the fifth wall portion 2125 and the surface of the first wall portion 211 facing away from the interior of the housing 212 (first surface 2111) are connected by a fourth chamfered surface 2129. Along the length direction Z of the first wall portion, the dimension of the third chamfered surface 2128 is R3, and the dimension of the fourth chamfered surface 2129 is R3. Then, the dimension d of the first surface 2111 is the distance between the outer surfaces of the fourth wall portion 2124 and the outer surfaces of the fifth wall portion 2125 along the length direction Z of the first wall portion, minus the dimension of the third chamfered surface 2128 in the width direction Y of the first wall portion, and minus the dimension of the fourth chamfered surface 2129 in the width direction Y of the first wall portion, i.e., d = d, - R3 - R4. The third chamfered surface 2128 and the fourth chamfered surface 2129 can be chamfered or rounded surfaces. In the embodiment where the third chamfered surface 2128 and the fourth chamfered surface 2129 are rounded surfaces, R3 may be the radius of the first chamfered surface 2126 , and R4 may be the radius of the second chamfered surface 2127 .

[0263] Exemplarily, as shown in FIG3 , the first wall portion 211 is an end cap 213, which covers the opening 2121 of the housing 212. Along the width direction Y of the first wall portion, the housing 212 has a second wall portion 2122 and a third wall portion 2123, which are opposed to each other. One end of the second wall portion 2122 forming the opening 2121 and one end of the third wall portion 2123 forming the opening 2121 are respectively connected to opposite ends of the end cap 213. Along the length direction Z of the first wall portion, the housing 212 has a fourth wall portion 2124 and a fifth wall portion 2125, which are opposed to each other. One end of the fourth wall portion 2124 forming the opening 2121 and one end of the fifth wall portion 2125 forming the opening 2121 are respectively connected to opposite ends of the end cap 213.

[0264] As shown in FIG3 , if the end cap 213 and the housing 212 are not easily disassembled, the dimension c of the first surface 2111 in the width direction Y of the first wall can be obtained by measuring the distance c' between the outer surface of the second wall portion 2122 and the outer surface of the third wall portion 2123 in the width direction Y of the first wall portion. The dimension d of the first surface 2111 in the length direction Z of the first wall can be obtained by measuring the distance d' between the outer surface of the fourth wall portion 2124 and the outer surface of the fifth wall portion 2125 in the length direction Z of the first wall. As shown in FIG4 , if the end cap 213 and the housing 212 are easily disassembled, the dimensions c and d of the end cap 213 in the length direction Z of the first wall can be directly measured.

[0265] In an embodiment where the first wall portion 211 is a wall portion of the housing 212, illustratively, as shown in FIG11 , the first wall portion 211 is the bottom wall of the housing 212, disposed opposite the end cap 213. Along the width direction Y of the first wall portion, the housing 212 has a second wall portion 2122 and a third wall portion 2123, which are opposed to each other. The second wall portion 2122 and the third wall portion 2123 are respectively connected to opposite ends of the first wall portion 211. Along the length direction Z of the first wall portion, the housing 212 has a fourth wall portion 2124 and a fifth wall portion 2125, which are respectively connected to opposite ends of the first wall portion 211. Along the width direction Y of the first wall portion, the distance between the outer surface of the second wall portion 2122 and the outer surface of the third wall portion 2123 is c'. A first chamfered surface 2126 connects the second wall portion 2122 between its outer surface in the width direction Y and the surface of the first wall portion 211 facing away from the interior of the housing 21 (first surface 2111). A second chamfered surface 2127 connects the third wall portion 2123 between its outer surface in the width direction Y and the surface of the first wall portion 211 facing away from the interior of the housing 21 (first surface 2111). Both the first chamfered surface 2126 and the second chamfered surface 2127 are rounded surfaces, with a radius of R1 for the first chamfered surface 2126 and a radius of R2 for the second chamfered surface 2127. c = c' - R1 - R2.

[0266] Along the length direction Z of the first wall, the distance between the outer surface of the fourth wall portion 2124 and the outer surface of the fifth wall portion 2125 is d'. A third chamfered surface 2128 connects the outer surface of the first wall portion in the length direction Z to the surface of the first wall portion 211 facing away from the interior of the housing 21 (first surface 2111). A fourth chamfered surface 2129 connects the outer surface of the first wall portion in the length direction Z to the surface of the first wall portion 211 facing away from the interior of the housing 21. Both the third chamfered surface 2128 and the fourth chamfered surface 2129 are rounded surfaces. The radius of the third chamfered surface 2128 is R3, and the radius of the fourth chamfered surface 2129 is R4. d = d' - R3 - R4.

[0267] Illustratively, c can be 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, etc.

[0268] d can be 100mm, 110mm, 120mm, 140mm, 150mm, 160mm, 170mm, 200mm, 230mm, 250mm, 260mm, etc.

[0269] The first wall portion 211 is a rectangular wall portion, which facilitates the manufacturing and molding of the battery cell 20 and also facilitates the area measurement of the first surface 2111 .

[0270] In some embodiments, the first wall portion 211 is a rectangular wall portion; along the length direction Z of the first wall portion, the pressure relief component 22 forms at least one predetermined pressure relief area P, and the sum of the sizes a of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is 0.1 to 0.5 times the size d of the first surface 2111 along the length direction Z of the first wall portion.

[0271] Along the length direction Z of the first wall portion, the pressure relief component 22 may form one predetermined pressure relief area P, or may form multiple predetermined pressure relief areas P.

[0272] In an embodiment in which the pressure relief component 22 forms a predetermined pressure relief area P along the length direction Z of the first wall portion, the sum a of the sizes of all predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is the size of the predetermined pressure relief area P along the length direction Z of the first wall portion.

[0273] In an embodiment in which the pressure relief component 22 forms a plurality of predetermined pressure relief areas P along the length direction Z of the first wall portion, the plurality of predetermined pressure relief areas P are arranged in sequence along the length direction Z of the first wall portion, and two adjacent predetermined pressure relief areas P may share a boundary. Then, the sum a of the sizes of all predetermined pressure relief areas P arranged along the length direction Z of the first wall portion may be the size between the farthest-spaced boundaries of the two predetermined pressure relief areas P that are farthest apart among the plurality of predetermined pressure relief areas P.

[0274] The sum a of the sizes of all predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is 0.1 to 0.5 times the size d of the first surface 2111 along the length direction Z of the first wall portion, that is, the ratio of the sum a of the sizes of all predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the size d of the first surface 2111 along the length direction Z of the first wall portion is 0.1 to 0.5. Exemplarily, a / d can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.45, 0.5, etc.

[0275] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to Examples 8-13. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0276] Fatigue testing of the battery cells 20 in Examples 8-13 was performed to determine the number of fatigue cycles experienced by the battery cells 20 during long-term use, and thermal runaway testing of the battery cells 20 was performed to determine the duration of the battery cells 20 experiencing thermal runaway, thereby evaluating the reliability of the battery cells 20. The specific results are shown in Table 2. The methods for testing the number of fatigue cycles and the duration of the battery cells 20 experiencing thermal runaway during use refer to the methods described above. The difference between Examples 1 and 8-13 lies in the difference in the dimension d of the first surface 2111 along the longitudinal direction Z of the first wall portion and the sum of the dimensions a of all predetermined pressure relief areas P arranged along the longitudinal direction Z of the first wall portion.

[0277] Table 2:

[0278] Table 2 shows that as a / d increases, the holding time of the battery cell 20 decreases. Specifically, as a / d increases, the battery cell 20's timely pressure relief performance improves, and the probability of explosion during thermal runaway decreases. Furthermore, as a / d increases, the fatigue life of the battery cell 20 decreases. Specifically, as a / d increases, the likelihood of the battery cell 20 opening and leaking due to fatigue increases, and the reliability of the battery cell 20 decreases.

[0279] In Table 2, when a / d ≥ 0.1, the battery cell 20's holding time is shorter, increasing the likelihood that the pressure relief component 22 of the battery cell 20 will release pressure promptly and reducing the risk of rupture, explosion, or fire in the battery cell 20's housing 21 due to untimely pressure relief from the pressure relief component 22. When a / d ≤ 0.5, the battery cell 20 experiences a greater number of fatigue events, resulting in a longer fatigue life for the battery cell 20. This further reduces the risk of leakage from the battery cell 20 due to premature activation or fatigue cracking of the pressure relief component 22 in the area corresponding to the first groove 221 after long-term use. Therefore, 0.1≤a / d≤0.5 can further reduce the risk of bursting, explosion, fire, etc. in the outer shell 21 of the battery cell 20 due to the untimely pressure relief of the pressure relief component 22, and further reduce the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component 22 at the corresponding position of the first groove 221 of the battery cell 20 after long-term use, thereby improving the use stability of the pressure relief component 22 and improving the service life and reliability of the battery cell 20.

[0280] Therefore, the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is 0.1 to 0.5 times the size d of the first surface 2111 along the length direction Z of the first wall portion, that is, the ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the size d of the first surface 2111 in the length direction Z of the first wall portion is limited to 0.1 to 0.5, wherein the ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the size d of the first surface 2111 in the length direction Z of the first wall portion is greater than or equal to 0.1, which can alleviate the phenomenon that the pressure bearing capacity of the bottom wall of the first groove 221 is too large, resulting in excessive bursting pressure required by the pressure relief component 22 when the battery cell 20 is relieved of pressure, thereby reducing the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, and further effectively improving the reliability of the battery cell 20. The ratio of the sum a of the sizes of all predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the size d of the first surface 2111 in the length direction Z of the first wall portion is less than or equal to 0.5, which can reduce the deformation of the bottom wall of the first groove 221 when the expansion force generated by the expansion of the battery cell 20 acts on the pressure relief component 22 during use, thereby reducing the structural strength of the bottom wall of the first groove 221 of the pressure relief component 22 due to excessive deformation, and further reducing the possibility of premature actuation or fatigue cracking of the pressure relief component 22 at the corresponding position of the first groove 221 after long-term use of the battery cell 20. The risk of leakage caused by the phenomenon is reduced, so as to improve the use stability of the pressure relief component 22 and improve the service life and use reliability of the battery cell 20. Therefore, 0.05≤a / d≤0.6 can take into account the reduction of the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to the untimely pressure relief of the pressure relief component 22, and the reduction of the risk of leakage caused by the premature actuation or fatigue cracking of the pressure relief component 22 at the corresponding position of the first groove 221 of the battery cell 20 after long-term use, so as to improve the use stability of the pressure relief component 22 and improve the service life and use reliability of the battery cell 20.

[0281] Please continue to refer to Table 2. As d decreases, the holding time of the battery cell 20 gradually becomes shorter, and the number of fatigue times of the battery cell 20 gradually decreases. When d≥100mm, the fatigue times of the battery cell 20 are large, and the risk of fatigue valve opening and leakage during long-term use of the battery cell 20 is low. When d≤260mm, the holding time of the battery cell 20 during thermal runaway is short, so that the pressure relief of the battery cell 20 is more timely. Therefore, when 100mm≤d≤260mm, the risk of the battery cell 20 bursting, exploding, catching fire, etc. due to the untimely pressure relief of the pressure relief component 22 of the battery cell 20 is lower, and the risk of leakage caused by the pressure relief component 22 of the battery cell 20 being prematurely actuated or fatigue cracked at the corresponding position of the first groove 221 after long-term use is lower, so as to improve the use stability of the pressure relief component 22 and improve the service life and reliability of the battery cell 20.

[0282] In some embodiments, the first wall portion 211 is a rectangular wall portion; along the width direction Y of the first wall portion, the first groove 221 defines at least one predetermined pressure relief area P, and the sum of the sizes of all predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is b, which is 0.3 times to 0.7 times the size c of the first surface 2111 along the width direction Y of the first wall portion.

[0283] Along the width direction Y of the first wall portion, the pressure relief component 22 may form one predetermined pressure relief area P, or may form a plurality of predetermined pressure relief areas P.

[0284] In an embodiment in which the pressure relief component 22 forms a predetermined pressure relief area P along the width direction Y of the first wall portion, the sum b of the sizes of all predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is the size of the predetermined pressure relief area P along the width direction Y of the first wall portion.

[0285] In an embodiment in which the pressure relief component 22 forms a plurality of predetermined pressure relief areas P along the width direction Y of the first wall portion, the plurality of predetermined pressure relief areas P are arranged in sequence along the width direction Y of the first wall portion, and two adjacent predetermined pressure relief areas P may share a boundary. Then, the sum b of the sizes of all predetermined pressure relief areas P arranged along the width direction Y of the first wall portion may be the size between the farthest boundaries of the two predetermined pressure relief areas P that are farthest apart among the plurality of predetermined pressure relief areas P.

[0286] The sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall is 0.3 to 0.7 times the size c of the first surface 2111 along the width direction Y of the first wall. That is, the ratio b of the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall to the size c of the first surface 2111 along the width direction Y of the first wall is 0.3 to 0.7. For example, b / c can be 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, etc.

[0287] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to Examples 14-20. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0288] Fatigue testing of the battery cells 20 in Examples 14-20 was performed to determine the number of fatigue cycles experienced by the battery cells 20 during long-term use, thereby evaluating the reliability of the battery cells 20. Furthermore, the flatness of the surface of the battery cells 20 along the width direction Y of the first wall of the housing 21 was evaluated by testing the extent of material buildup on either of the two surfaces of the housing 21 along the width direction Y of the first wall due to the formation of the first groove 221. The details are shown in Table 3. The method for testing the number of fatigue cycles experienced by the battery cells 20 during use can refer to the method described above.

[0289] The method for testing the degree of stacking of the battery cells 20 on any one of the two surfaces of the housing 21 along the width Y direction of the first wall due to the formation of the first groove 221 is as follows:

[0290] For ease of description, the two opposing outer surfaces of the housing 21 along the width direction Y of the first wall are defined as measurement surfaces. Four reference points are located along the length direction Z of the first wall, one on each measurement surface. These four reference points are located on either side of the first groove 221 along the length direction of the first wall. The plane formed by these four reference points is the reference surface, which is parallel to the measurement surface before the first groove 221 is formed. A detection point is acquired in the area of ​​the measurement surface corresponding to the first groove 221, and the distance from the detection point to the reference surface in the width direction Y of the first wall is measured to determine the degree of material accumulation on the measurement surface caused by the manufacturing of the first groove 221. The greater the distance between the detection point and the reference surface in the width direction Y of the first wall, the greater the degree of material accumulation and the worse the surface flatness of the housing 21 in the width direction Y of the first wall. Conversely, the smaller the distance between the detection point and the reference surface in the width direction Y of the first wall, the less material accumulation and the better the surface flatness of the housing 21 in the width direction Y of the first wall.

[0291] The difference between Example 1 and Example 14 to Example 20 is that the dimension c of the first surface 2111 along the width direction Y of the first wall portion and the sum b of the dimensions of all predetermined pressure relief areas P arranged along the width direction Y of the first wall portion in the length direction Z of the first wall portion are different.

[0292] Table 3:

[0293] As shown in Table 3, as the ratio b / c increases, the duration of the battery cell 20's air holding time decreases. Specifically, as b / c increases, the battery cell 20's timely pressure relief performance improves, and the probability of explosion during thermal runaway decreases. As b / c increases, during the manufacturing process of forming the first groove 221, localized material accumulation in the outer shell 21 of the battery cell 20 in the width direction Y of the first wall becomes more severe, and the flatness of the two outer surfaces of the battery cell 20 in the width direction Y of the outer shell 21 of the battery cell 20 decreases.

[0294] In Table 3, when b / c ≥ 0.3, the battery cell 20 has a shorter holding time, which increases the likelihood that the pressure relief component 22 of the battery cell 20 will release pressure in a timely manner, reducing the risk of the battery cell 20's housing 21 bursting, exploding, or catching fire due to untimely pressure relief from the pressure relief component 22. When b / c ≤ 0.7, the degree of accumulation of material on both surfaces of the battery cell 20's housing 212 in the width direction Y of the first wall portion is reduced, resulting in a better surface flatness of the battery cell 20's housing 21 in the width direction Y of the first wall portion. Therefore, when 0.3 ≤ b / c ≤ 0.7, the risk of bursting, exploding, or catching fire due to untimely pressure relief from the pressure relief component 22 can be reduced, as well as the degree of accumulation of material on the housing 212 in the width direction Y of the first wall portion during the manufacturing process of the first groove 221.

[0295] Therefore, the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is 0.3 to 0.7 times the size c of the first surface 2111 along the width direction Y of the first wall portion, that is, the ratio of the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion to the size of the first surface 2111 in the curling direction of the first wall portion 211 is limited to 0.3 to 0.7. Among them, by making the ratio of the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion to the size of the first surface 2111 in the curling direction of the first wall portion 211 greater than or equal to 0.3, the phenomenon that the pressure bearing capacity of the bottom wall of the first groove 221 is too large, resulting in the pressure relief component 22 requiring too large a bursting pressure when the battery cell 20 is relieved, can be alleviated, thereby reducing the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, and further effectively improving the reliability of the battery cell 20. By making the ratio of the sum of the sizes b of all predetermined pressure relief areas P arranged along the width direction Y of the first wall portion to the size of the first surface 2111 in the curl direction of the first wall portion 211 less than or equal to 0.7, the degree of material stacking in the width direction Y of the first wall portion during the manufacturing process of the first groove 221 can be reduced, thereby alleviating the problem of poor flatness of the surface of the battery cell 20 in the width direction Y of the first wall portion due to the formation of the first groove 221.

[0296] Continuing with Table 3, as c increases, the holding time of the battery cell 20 gradually shortens, and the degree to which the two opposing outer surfaces of the outer shell 21 of the battery cell 20, along the width direction Y of the first wall, protrude from the reference plane gradually increases. When c ≥ 55 mm, the holding time of the battery cell 20 during thermal runaway is shorter, facilitating timely pressure relief in the event of thermal runaway, and reducing the probability of explosion in the event of thermal runaway. When c ≤ 85 mm, the degree to which the two opposing outer surfaces of the battery cell 20, along the width direction Y of the first wall, protrude from the reference plane less, the outer shell 21 has less material accumulation along the width direction of the first wall, and the two opposing outer surfaces of the outer shell 21, along the width direction Y of the first wall, have better flatness. Therefore, when 55mm≤c≤85mm, the risk of the battery cell 20 bursting, exploding, or catching fire in the outer shell 21 of the battery cell 20 due to the untimely pressure relief of the pressure relief component 22 is low, so that the reliability of the battery cell 20 is better and the flatness of the two opposite outer surfaces of the outer shell 21 of the battery cell 20 along the width direction Y of the first wall portion is better.

[0297] In some embodiments, the first wall portion 211 is a rectangular wall portion; along the length direction Z of the first wall portion, the pressure relief component 22 forms at least one predetermined pressure relief area P, and the sum of the sizes of all predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is a, 26mm≤a≤50mm.

[0298] Along the length direction Z of the first wall portion, the pressure relief component 22 may form one predetermined pressure relief area P, or may form multiple predetermined pressure relief areas P.

[0299] As shown in Figures 9, 10, 11, 13, 14, 15, 16 and 17, in an embodiment in which the pressure relief component 22 forms a predetermined pressure relief area P along the length direction Z of the first wall portion, the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is the size of the predetermined pressure relief area P along the length direction Z of the first wall portion.

[0300] As shown in FIG21 , in an embodiment where the pressure relief component 22 forms multiple predetermined pressure relief areas P along the length direction Z of the first wall portion, the multiple predetermined pressure relief areas P are arranged sequentially along the length direction Z of the first wall portion, and two adjacent predetermined pressure relief areas P may share a common boundary. Therefore, the sum a of the sizes of all predetermined pressure relief areas P arranged along the length direction Z of the first wall portion may be the size between the farthest-spaced boundaries of two predetermined pressure relief areas P that are furthest apart from each other among the multiple predetermined pressure relief areas P. As shown in FIG21 , the pressure relief component 22 forms two predetermined pressure relief areas P along the length direction Z of the first wall portion. The two predetermined pressure relief areas P are arranged along the length direction Z of the first wall portion. The two predetermined pressure relief areas P may be bounded by the center line of the width direction of the second groove segment 2213 of the first groove. The sizes of the two predetermined pressure relief areas P along the length direction Z of the first wall portion are a1 and a2, respectively, where a=a1+a2.

[0301] Illustratively, a can be 26mm, 30mm, 32mm, 40mm, 42mm, 44mm, 46mm, 50mm, etc.

[0302] Continuing with Table 2, when a ≥ 26 mm, the battery cell 20's holding time is shorter, increasing the likelihood that the pressure relief component 22 of the battery cell 20 will release pressure in a timely manner and reducing the risk of bursting, explosion, or fire in the battery cell 20's housing 21 due to untimely pressure relief from the pressure relief component 22. When a ≤ 50 mm, the battery cell 20 experiences a greater number of fatigue events, resulting in a longer fatigue life for the battery cell 20. This further reduces the risk of leakage caused by premature activation or fatigue cracking of the pressure relief component 22 in the area corresponding to the first groove 221 after long-term use. Therefore, 26mm≤a≤50mm can further reduce the risk of bursting, explosion, fire, etc. of the outer shell 21 of the battery cell 20 due to the untimely pressure relief of the pressure relief component 22, and further reduce the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component 22 at the corresponding position of the first groove 221 of the battery cell 20 after long-term use, so as to improve the use stability of the pressure relief component 22 and improve the service life and reliability of the battery cell 20.

[0303] Therefore, the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is greater than or equal to 26 mm, which not only facilitates the processing and forming of the first groove 221 and defines the predetermined pressure relief area P, but also helps to increase the area of ​​the predetermined pressure relief area P, thereby alleviating the phenomenon that the pressure bearing capacity of the bottom wall of the first groove 221 is too large, resulting in the pressure relief component 22 requiring an excessively large bursting pressure when the battery cell 20 is relieved of pressure, thereby reducing the risk of bursting, explosion, fire, etc. in the outer shell 21 of the battery cell 20 due to untimely pressure relief of the pressure relief component 22, and further effectively improving the reliability of the battery cell 20. The sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is less than or equal to 50 mm, which can reduce the deformation of the bottom wall of the first groove 221 when the expansion force generated by expansion during the use of the battery cell 20 acts on the pressure relief component 22, thereby reducing the structural strength of the bottom wall of the first groove 221 of the pressure relief component 22 due to excessive deformation, and further reducing the risk of leakage caused by premature actuation or fatigue cracking of the pressure relief component 22 at the corresponding position of the first groove 221 after long-term use of the battery cell 20, thereby improving the use stability of the pressure relief component 22 and improving the service life and reliability of the battery cell 20.

[0304] In some embodiments, the first wall portion 211 is a rectangular wall portion; along the width direction Y of the first wall portion, the first groove 221 defines at least one predetermined pressure relief area P, and the sum of the sizes of all predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is b, 18mm≤b≤62mm.

[0305] Along the width direction Y of the first wall portion, the pressure relief component 22 may form one predetermined pressure relief area P, or may form a plurality of predetermined pressure relief areas P.

[0306] As shown in Figure 9, in an embodiment in which the pressure relief component 22 forms a predetermined pressure relief area P along the width direction Y of the first wall portion, the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is the size of the predetermined pressure relief area P along the width direction Y of the first wall portion.

[0307] As shown in Figures 10, 11, and 13-17, in an embodiment where the pressure relief component 22 forms multiple predetermined pressure relief areas P along the width direction Y of the first wall, the multiple predetermined pressure relief areas P are arranged sequentially along the width direction Y of the first wall. Two adjacent predetermined pressure relief areas P may share a common boundary. Therefore, the sum of the dimensions a of all predetermined pressure relief areas P arranged along the width direction Y of the first wall can be the dimension between the farthest-separated boundaries of the two predetermined pressure relief areas P that are furthest apart from each other. Figures 10, 11, and 13-17 illustrate that the pressure relief component 22 forms two predetermined pressure relief areas P along the width direction Y of the first wall. The two predetermined pressure relief areas P are arranged along the width direction Y of the first wall, with the width centerline of the second groove segment 2213 of the first groove 221 serving as the boundary. The dimensions of the two predetermined pressure relief areas P along the width direction Y of the first wall are b1 and b2, respectively, where b = b1 + b2.

[0308] Illustratively, b can be 18 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 62 mm, etc.

[0309] Continuing with Table 3, when b ≥ 18 mm, the battery cell 20's holding time is shorter, increasing the likelihood of timely pressure relief from the pressure relief component 22 of the battery cell 20 and reducing the risk of rupture, explosion, or fire in the battery cell 20's housing 21 due to untimely pressure relief from the pressure relief component 22. When b ≤ 62 mm, the degree of material accumulation on both surfaces of the battery cell 20's housing 21 in the width direction Y of the first wall is reduced, resulting in improved surface flatness of the battery cell 20's housing 21 in the width direction Y of the first wall. Therefore, when 18 mm ≤ b ≤ 62 mm, the risk of rupture, explosion, or fire in the battery cell 20's housing 21 due to untimely pressure relief from the pressure relief component 22 is reduced, as well as the degree of material accumulation on the housing 21 in the width direction Y of the first wall during the manufacturing process of the first groove 221, thereby improving the flatness of the two opposing outer surfaces of the housing 21 in the width direction Y of the first wall.

[0310] Therefore, the sum of the dimensions b of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall is greater than or equal to 18 mm. This not only facilitates the processing and forming of the first groove 221 and defines the predetermined pressure relief area P, but also helps increase the area of ​​the predetermined pressure relief area P, alleviating the problem of excessive pressure bearing capacity of the bottom wall of the first groove 221, which results in the pressure relief component 22 requiring an excessively high burst pressure when releasing pressure from the battery cell 20. This reduces the risk of bursting, explosion, or fire in the outer shell 21 of the battery cell 20 due to untimely pressure relief from the pressure relief component 22, thereby further effectively improving the reliability of the battery cell 20. The sum of the dimensions b of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall is less than or equal to 62 mm. This reduces the degree of material accumulation in the width direction Y of the first wall during the manufacturing process of the first groove 221, thereby alleviating the problem of poor surface flatness of the battery cell 20 in the width direction Y of the first wall caused by the formation of the first groove 221.

[0311] In some embodiments, the first wall portion 211 is a rectangular wall portion; along the length direction Z of the first wall portion, the pressure relief component 22 forms at least one predetermined pressure relief area P, and the sum of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is a; along the width direction Y of the first wall portion, the first groove 221 defines at least one predetermined pressure relief area P, and the sum of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is b; and the size of the first surface 2111 is c;

[0312] When 10mm≤c≤40mm, the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall is 2 to 3 times the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall.

[0313] The sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is 2 to 3 times the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion, that is, the ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is 2 to 3. Exemplarily, a / b can be 2, 2.1, 2.2, 2.25, 2.4, 2.5, 2.6, 2.7, 2.8, 3, etc.

[0314] A battery cell 20 that satisfies 10 mm ≤ c ≤ 40 mm can also be referred to as a narrow cell. FIG13 shows a case where c = 39 mm and a / b = 2.

[0315] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to Examples 21-40. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0316] When 10 mm ≤ c ≤ 40 mm, the explosion pressure and valve opening angle of the battery cell 20 during thermal runaway are obtained for the battery cells 20 in Examples 21 to 40 to evaluate the reliability of the battery cell 20. The specific conditions are shown in Table 4.

[0317] The difference between Example 1 and Example 21 to Example 40 lies in that the dimension c of the first surface 2111 along the width direction Y of the first wall portion, the sum of the dimensions a of all predetermined pressure relief areas P arranged along the length direction Z of the first wall portion in the length direction Z of the first wall portion, and the sum of the dimensions b of all predetermined pressure relief areas P arranged along the width direction Y of the first wall portion in the width direction Y of the first wall portion are different.

[0318] Taking the battery cell 20 with model number 39203 as an example, the first groove 221 has a preset standard burst pressure of 1 MPa. If the actual burst pressure of the battery cell 20 during thermal runaway satisfies 1.0±0.2 MPa, the burst pressure of the battery cell 20 is considered stable. The burst pressure stability is determined by the standard deviation of multiple burst pressures. The actual burst pressure is represented by σ. If the fluctuation value (σ-1) of the actual burst pressure of the battery cell 20 relative to the standard burst pressure of the battery cell 20 is less than 0.2 MPa, the burst pressure is considered stable. The actual burst pressure is the pressure at which the first groove 221 begins to rupture.

[0319] The actual burst pressure test method is as follows:

[0320] 1) Use two steel or aluminum plates as clamps to clamp the two large surfaces of the battery cell 20 with a clamping force of 3000N;

[0321] 2) Use a 3mm drill bit to drill a hole corresponding to the injection hole on the battery cell 20. Connect the inflation device to the hole drilled by the drill bit through the air pipe. Use the inflation device to inflate the battery cell 20 at a rate of 0.03 MPa / s. Install a pressure gauge on the air pipe to monitor the pressure inside the battery cell 20. The inflation device inflates the battery cell 20;

[0322] 3) The pressure inside the battery cell 20 monitored by the pressure gauge until the first groove ruptures and releases air is the actual bursting pressure of the battery cell 20 .

[0323] The valve opening state of a battery cell 20 is measured by the valve opening angle at the initial pressure relief of the first groove 221. As shown in Figure 12, this angle is the angle between the plane containing the predetermined pressure relief area P of the opening 2121 of the first groove 221 and the plane containing the predetermined pressure relief area P before the first groove 221 ruptures. The valve opening angle is represented by β, and a value of β > 45° is considered acceptable. A larger valve opening angle β indicates a larger pressure relief area. The test results for battery cells 20 of various sizes and proportions are shown below.

[0324] Table 4:

[0325] Please refer to Table 4. When c = 10mm, 20mm, 30mm, and 40mm, as a / b gradually increases, the valve opening angle gradually decreases. That is, as a / b gradually increases, the pressure relief area becomes smaller, and the pressure relief effect and efficiency become worse. As a / b gradually increases, the fluctuation of the burst pressure of each battery cell 20 relative to the standard burst pressure gradually decreases, and the burst pressure becomes more and more stable.

[0326] In Table 4, when c = 10 mm, 20 mm, 30 mm, and 40 mm, and when a / b ≥ 2, the bursting pressure of each battery cell 20 fluctuates less than the standard bursting pressure, and the bursting pressure is more stable, which is conducive to timely pressure relief of the battery cell 20 and the reliability of the battery cell 20. When a / b ≤ 3, the valve opening angle when the first groove 221 of the battery cell 20 ruptures is greater than 45°. The larger valve opening angle when the first groove 221 of the battery cell 20 ruptures results in a larger pressure relief area and better pressure relief effect and efficiency.

[0327] Therefore, when 10 mm ≤ c ≤ 40 mm, the sum of the sizes a of all the predetermined pressure relief zones P arranged along the length direction Z of the first wall portion is 2 to 3 times the sum of the sizes b of all the predetermined pressure relief zones P arranged along the width direction Y of the first wall portion. That is, the ratio of the sum of the sizes a of all the predetermined pressure relief zones arranged along the length direction Z of the first wall portion to the sum of the sizes b of all the predetermined pressure relief zones P arranged along the width direction Y of the first wall portion is 2 to 3. The ratio of the sum of the sizes a of all the predetermined pressure relief zones P arranged along the length direction Z of the first wall portion to the sum of the sizes b of all the predetermined pressure relief zones P arranged along the width direction Y of the first wall portion is greater than or equal to 2, and the bursting pressure is more stable, which is beneficial to the timely pressure relief of the pressure relief component 22. Thus, the risks such as bursting, explosion, and fire of the outer shell 21 of the battery cell 20 caused by the untimely pressure relief of the pressure relief component 22 can be reduced, and further, the use reliability of the battery cell 20 can be effectively improved. When the ratio of the sum of the sizes a of all the predetermined pressure relief zones P arranged along the length direction Z of the first wall portion to the sum of the sizes b of all the predetermined pressure relief zones P arranged along the width direction Y of the first wall portion is less than or equal to 3, when the first groove 221 cracks, the opening valve angle of the predetermined pressure relief zone P is larger, so that the pressure relief component 22 has a larger pressure relief area, which is beneficial to the timely pressure relief of the pressure relief component 22, reduces the risks such as bursting, explosion, and fire of the outer shell 21 of the battery cell 20, and improves the reliability of the battery cell 20.

[0328] In one embodiment, when 40 mm < c ≤ 60 mm, the sum of the sizes a of all the predetermined pressure relief zones P arranged along the length direction Z of the first wall portion is 1 to 2 times the sum of the sizes b of all the predetermined pressure relief zones P arranged along the width direction Y of the first wall portion.

[0329] The sum of the sizes a of all the predetermined pressure relief zones P arranged along the length direction Z of the first wall portion is 1 to 2 times the sum of the sizes b of all the predetermined pressure relief zones P arranged along the width direction Y of the first wall portion. That is, the ratio of the sum of the sizes a of all the predetermined pressure relief zones P arranged along the length direction Z of the first wall portion to the sum of the sizes b of all the predetermined pressure relief zones P arranged along the width direction Y of the first wall portion is 1 to 2. Exemplarily, a / b can be 1, 1.2, 1.4, 1.5, ............1.6, 1.7, 1.8, 2, etc.

[0330] The battery cell 20 satisfying 40 mm < c ≤ 60 mm can also be called a medium-thick battery core. As shown in FIG. 14, the case where c = 50 mm and a / b = 1.0 is shown.

[0331] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail in combination with Embodiments 41-55. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0332] When 40mm < c ≤ 60mm, the bursting pressure and the valve opening angle at the time of bursting of the battery cell 20 in Embodiments 73-96 are obtained for the battery cell 20 to evaluate the reliability of the battery cell 20. The specific situation is shown in Table 5. The test methods for the bursting pressure and the valve opening angle at the time of bursting are as above. The model of the test object used in Embodiments 41-Embodiment 55 is 54203.

[0333] The differences between Embodiment 1 and Embodiments 41-Embodiment 55 are that the dimension c of the first surface 2111 along the width direction Y of the first wall portion, the sum a of the dimensions of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion in the length direction Z of the first wall portion, and the sum b of the dimensions of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion in the width direction Y of the first wall portion are different.

[0334] Table 5:

[0335] As can be seen from Table 5, when c = 50mm, 55mm, and 60mm, as a / b gradually increases, the valve opening angle gradually decreases. That is, as a / b gradually increases, the pressure relief area becomes smaller, and the pressure relief effect and pressure relief efficiency become worse; as a / b gradually increases, the fluctuation of the bursting pressure of each battery cell 20 relative to the standard bursting pressure gradually decreases, and the bursting pressure becomes more stable.

[0336] In Table 5, when c = 50mm, 55mm, and 60mm, when a / b ≥ 1, the fluctuation of the bursting pressure of each battery cell 20 relative to the standard bursting pressure is small, and the bursting pressure is more stable, which is beneficial to the timely pressure relief of the battery cell 20 and the reliability of the battery cell 20; when a / b ≤ 2, when the first groove 221 of the battery cell 20 cracks, the valve opening angle is greater than 45°, and when the first groove 221 of the battery cell 20 cracks, the valve opening angle is relatively large, so that the pressure relief area is relatively large, and the pressure relief effect and pressure relief efficiency are relatively good.

[0337] Therefore, when 40 mm < c ≤ 60 mm, the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is 1 to 2 times the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion. That is, the ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is 1 to 2. The ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is greater than or equal to 1, and the bursting pressure is more stable, which is beneficial to the timely pressure relief of the pressure relief component 22. Thus, the risks such as bursting, explosion, and fire of the outer shell 21 of the battery cell 20 caused by the untimely pressure relief of the pressure relief component 22 can be reduced, and the use reliability of the battery cell 20 can be effectively improved. The ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is less than or equal to 2, which is beneficial to a larger opening valve angle of the predetermined pressure relief area P when the first groove 221 cracks, so that the pressure relief component 22 has a larger pressure relief area, which is beneficial to the timely pressure relief of the pressure relief component 22, reduces the risks such as bursting, explosion, and fire of the outer shell 21 of the battery cell 20, and improves the reliability of the battery cell 20.

[0338] In some embodiments, when 60 mm < c, the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is 0.4 to 1 times the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion.

[0339] The sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is 0.4 to 1 times the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion. That is, the ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is 0.4 to 1. Exemplarily, a / b can be 0.4, 0.5, 0.6, 0.7, 0.8, 1, etc.

[0340] The battery cell 20 with 60 mm < c can also be called a thick battery cell. As shown in FIG. 15, the case where c = 71 mm and a / b = 0.6 is shown. As shown in FIG. 16, the case where c = 87 mm and a / b = 0.5 is shown.

[0341] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to Embodiments 56-73. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0342] When 60mm < c, by obtaining the bursting pressure and the valve opening angle at the time of bursting of the battery cell 20 in Embodiments 56-73 for the battery cell 20, the reliability of the battery cell 20 is evaluated. The specific situation is shown in Table 6. The test methods for the bursting pressure and the valve opening angle at the time of bursting are as above.

[0343] The model number of the test object used in Embodiments 56-73 is 87203.

[0344] The differences between Embodiment 1 and Embodiments 56-73 are that the dimension c of the first surface 2111 along the width direction Y of the first wall portion, the sum a of the dimensions of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion in the length direction Z of the first wall portion, and the sum b of the dimensions of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion in the width direction Y of the first wall portion are different.

[0345] Table 6

[0346] As can be seen from Table 6, when c = 70mm, 80mm, 90mm, as a / b gradually increases, the valve opening angle gradually decreases. That is, as a / b gradually increases, the pressure relief area becomes smaller, and the pressure relief effect and pressure relief efficiency become worse; as a / b gradually increases, the fluctuation of the bursting pressure of each battery cell 20 relative to the standard bursting pressure gradually decreases, and the bursting pressure becomes more stable.

[0347] In Table 6, when c = 70mm, 80mm, 90mm, when a / b ≥ 0.4, the fluctuation of the bursting pressure of each battery cell 20 relative to the standard bursting pressure is small, the fluctuation of the bursting pressure of each battery cell 20 relative to the standard bursting pressure is small, and the bursting pressure is more stable, which is beneficial to the timely pressure relief of the battery cell 20 and the improvement of the reliability of the battery cell 20; when a / b ≤ 1, when the first groove 221 of the battery cell 20 cracks, the valve opening angle is greater than 45°, and the valve opening angle when the first groove 221 of the battery cell 20 cracks is large, so that the pressure relief area is large, and the pressure relief effect and pressure relief efficiency are good.

[0348] Therefore, when 60 mm < c, the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion is 0.4 times to 1 times the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion. That is, the ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is 0.4 to 1. The ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is greater than or equal to 0.4, and the bursting pressure is more stable, which is beneficial to the timely pressure relief of the pressure relief component 22. Thus, the risks such as bursting, explosion, and fire of the outer shell 21 of the battery cell 20 caused by the untimely pressure relief of the pressure relief component 22 can be reduced, and further, the use reliability of the battery cell 20 can be effectively improved. The ratio of the sum a of the sizes of all the predetermined pressure relief areas P arranged along the length direction Z of the first wall portion to the sum b of the sizes of all the predetermined pressure relief areas P arranged along the width direction Y of the first wall portion is less than or equal to 1, which is beneficial to a larger opening valve angle of the predetermined pressure relief area P when the first groove 221 cracks, so that the pressure relief component 22 has a larger pressure relief area, which is beneficial to the timely pressure relief of the pressure relief component 22 and reduces the risks such as bursting, explosion, and fire of the outer shell 21 of the battery cell 20, and improves the reliability of the battery cell 20.

[0349] As shown in FIG. 17, in some embodiments, the pressure relief component 22 further includes a second groove 222, and the second groove 222 is configured to guide the opening of the predetermined pressure relief area P.

[0350] The bottom wall of the second groove 222 forms a second weak portion 2221. That is to say, the portion corresponding to the bottom wall of the second groove 222 at the position where the pressure relief component 22 is provided with the second groove 222 is the second weak portion 2221.

[0351] Along the thickness direction X of the first wall portion, the thickness of the second weak portion 2221 is greater than the thickness of the first weak portion 2211 formed by the bottom wall of the first groove 221. The second weak portion 2221 is configured to guide the flipping of the predetermined pressure relief area P when the first weak portion 2211 cracks, so as to release the internal pressure of the battery cell 20, thereby realizing the opening of the predetermined pressure relief area P guided by the second groove 222.

[0352] Among them, the second weak portion 2221 is configured to guide the flipping of the predetermined pressure relief area P when the bottom wall of the first groove 221 cracks. That is to say, the predetermined pressure relief area P can flip around the second weak portion 2221 after the bottom wall of the first groove 221 of the pressure relief component 22 cracks, so as to facilitate the communication between the inside and the outside of the outer shell 21 after the flipping of the predetermined pressure relief area P for pressure relief.

[0353] Of course, in other embodiments, the second weak portion 2221 may also be other structures. For example, the second weak portion 2221 may be formed by heat treating a part of the pressure relief component 22 to weaken the strength of the area.

[0354] The pressure relief component 22 is provided with a second groove 222. A weakened portion is formed in the area corresponding to the second groove 222. The weakened portion corresponding to the second groove 222 can guide the opening of the predetermined pressure relief area P, thereby improving the opening efficiency of the predetermined pressure relief area P of the pressure relief component 22. This increases the pressure relief area of ​​the battery cell 20 after the predetermined pressure relief area P is opened. This, in turn, increases the pressure relief rate of the battery cell 20 in the event of thermal runaway, thereby reducing the risk of fire, explosion, connection failure, and other issues caused by untimely pressure relief in the battery cell 20, and thus improving the reliability of the battery cell 20. The second groove 222 is provided on the pressure relief component 22, forming a weakened portion in the area corresponding to the bottom surface of the second groove 222. Battery cells 20 employing this structure facilitate forming a weakened portion on the pressure relief component 22, thereby reducing the difficulty of forming a weakened portion on the pressure relief component 22 to guide the opening of the predetermined pressure relief area P, thereby improving the production efficiency of the battery cell 20.

[0355] In some embodiments, the second groove 222 is recessed from the second surface 2112 toward the first surface 2111 .

[0356] The first groove 221 is provided on the first surface 2111, and the second groove 222 is provided on the second surface 2112. The first surface 2111 and the second surface 2112 are surfaces on opposite sides of the pressure relief component 22 in the thickness direction X of the first wall. The first groove 221 and the second groove 222 are provided on opposite sides of the pressure relief component 22 along the thickness direction X of the first wall.

[0357] Exemplarily, the first groove 221 is arranged on the surface of the pressure relief component 22 facing away from the interior of the shell 21, and the second groove 222 is arranged on the surface of the pressure relief component 22 facing the interior of the shell 21, so that the first groove 221 and the second groove 222 are respectively arranged on both sides of the pressure relief component 22.

[0358] The second groove 222 is recessed from the second surface 2112 toward the first surface 2111, and the first groove 221 and the second groove 222 are arranged on opposite sides of the pressure relief component 22 along the thickness direction X of the first wall portion, so as to facilitate the processing of the first groove 221 and the second groove 222 on both sides of the pressure relief component 22 along the thickness direction X of the first wall portion, respectively, which is beneficial to reducing the mutual influence of the first groove 221 and the second groove 222 during the processing.

[0359] As shown in Figures 17, 18, 19 and 20, in some embodiments, the first surface 2111 is the surface of the pressure relief component 22 facing away from the interior of the housing 21, and the second surface 2112 is the surface of the pressure relief component 22 facing the interior of the housing 21.

[0360] That is, the first groove 221 is provided on the surface of the pressure relief component 22 facing away from the interior of the housing 21, and the first groove 221 is recessed from the first surface 2111 toward the second surface 2112. The second groove 222 is provided on the surface of the pressure relief component 22 facing the interior of the housing 21, and the second groove 222 is recessed from the second surface 2112 toward the first surface 2111.

[0361] By disposing the first groove 221 and the second groove 222, respectively, on the first surface 2111 and the second surface 2112 of the pressure relief component 22, which are opposite each other along the thickness direction X of the first wall, it is facilitated to process the first groove 221 and the second groove 222 on both sides of the pressure relief component 22 along the thickness direction X of the first wall, thereby facilitating the reduction of mutual interference between the first groove 221 and the second groove 222 during the processing. Furthermore, by disposing the second groove 222 on the second surface 2112 of the pressure relief component 22 facing the interior of the housing 21, the predetermined pressure relief area P, after being opened, can be flipped around the bottom wall of the second groove 222 toward the outside of the housing 21. This can reduce the interference caused by the side surface of the second groove 222 on the predetermined pressure relief area P during the flipping process, thereby facilitating the flipping effect of the predetermined pressure relief area P.

[0362] As shown in FIG. 17 , in some embodiments, the first groove 221 and the second groove 222 are not in contact.

[0363] By setting the first groove 221 and the second groove 222 to a structure that does not contact each other, on the one hand, the mutual influence between the first groove 221 and the second groove 222 during the processing process can be reduced; on the other hand, the phenomenon of the corresponding area of ​​the second groove 222 cracking when the first groove 221 cracks to release pressure can be reduced, and the stress influence between the first groove 221 and the second groove 222 can be reduced.

[0364] Of course, in other embodiments, as shown in FIG. 11 , the pressure relief component 22 may not be provided with the second groove 222 .

[0365] In an embodiment where the first groove 221 includes multiple groove segments, exemplarily, as shown in FIG17 , the first groove 221 includes a first groove segment 2212 and a second groove segment 2213 , the first groove segment 2212 and the second groove segment 2213 are connected, and the first groove segment 2212 and the second groove segment 2213 jointly define at least one predetermined pressure relief area P.

[0366] The first groove section 2212 can extend in a straight line. The second groove section 2213 can extend in a straight line. The first groove section 2212 and the second groove section 2213 together define at least one predetermined pressure relief area P. The predetermined pressure relief area P is configured to be opened when the pressure relief component 22 is ruptured along at least a portion of the bottom wall of the first groove 221 to relieve pressure within the battery cell 20.

[0367] The first slot section 2212 may also extend along a curve, for example, the first slot section 2212 is an arc section. The second slot section 2213 may also extend along a curve, for example, the second slot section 2213 is an arc section.

[0368] The first slot section 2212 and the second slot section 2213 each form a first weak section 2211a, and the first weak portion 2211 can include two first weak sections 2211a. Because the first slot section 2212 and the second slot section 2213 are connected, the first weak section 2211a formed in the first slot section 2212 and the first weak section 2211a formed in the second slot section 2213 are connected, forming a first weak portion 2211 comprising the two connected first weak sections 2211a. When one first weak section 2211a begins to rupture, it can drive the other first weak section 2211a to rupture as well.

[0369] The first groove section 2212 and the second groove section 2213 jointly define a predetermined pressure relief area P, that is, the first groove section 2212 and the second groove section 2213 are structures arranged along the edge of the predetermined pressure relief area P, so that the setting trajectory of the first groove 221 is set along the edge of the predetermined pressure relief area P.

[0370] The predetermined pressure relief area P is configured to be able to be opened when the first weak portion 2211 formed along the bottom wall of at least part of the first groove 221 of the pressure relief component 22 is cracked, that is, when the battery cell 20 undergoes thermal runaway and releases internal pressure, the area of ​​the first groove section 2212 and the second groove section 2213 of the pressure relief component 22 can be cracked, so that the predetermined pressure relief area P can be opened and the internal pressure of the battery cell 20 can be released.

[0371] The first slot segment 2212 and the second slot segment 2213 can be connected in various forms, for example, the first slot segment 2212 and the second slot segment 2213 are connected to form a "T" shape, the first slot segment 2212 and the second slot segment 2213 are connected to form a "V" shape, the first slot segment 2212 and the second slot segment 2213 are connected to form an "L" shape, the first slot segment 2212 and the second slot segment 2213 are connected to form an "X" shape, etc.

[0372] The first groove 221 includes a first groove section 2212 and a second groove section 2213, and the first groove section 2212 and the second groove section 2213 are interconnected structures. On the one hand, they can increase the pressure relief area of ​​the battery cell 20 to increase the pressure relief rate of the battery cell 20. On the other hand, the position where the first groove section 2212 and the second groove section 2213 are interconnected is weaker, which is easier to crack and open the predetermined pressure relief area P to release the internal pressure of the battery cell 20.

[0373] In some embodiments, the first groove 221 also includes a third groove section 2214, the first groove section 2212 and the third groove section 2214 are arranged opposite to each other, the second groove section 2213 connects the first groove section 2212 and the third groove section 2214, and the first groove section 2212, the second groove section 2213 and the third groove section 2214 jointly define at least one predetermined pressure relief area P.

[0374] The third groove section 2214 can extend in a straight line. The first groove section 2212, the second groove section 2213, and the third groove section 2214 collectively define a predetermined pressure relief area P. The predetermined pressure relief area P is configured to be opened when the first weakened portion formed by the pressure relief component 22 along at least a portion of the bottom wall of the first groove 221 is not broken, thereby releasing the internal pressure of the battery cell 20.

[0375] The extending direction of the first slot segment 2212 is parallel to the extending direction of the third slot segment 2214. The extending direction of the first slot segment 2212 is perpendicular to the extending direction of the second slot segment 2213. The extending direction of the third slot segment 2214 is perpendicular to the extending direction of the second slot segment 2213. In other words, the first slot segment 2212 and the third slot segment 2214 are respectively perpendicular to the second slot segment 2213.

[0376] The first slot segment 2212, the second slot segment 2213 and the third slot segment 2214 can be connected in various forms, for example, the first slot segment 2212, the second slot segment 2213 and the third slot segment 2214 are connected to form an "H" shape, or the first slot segment 2212, the second slot segment 2213 and the third slot segment 2214 are connected to form a "U" shape.

[0377] In other embodiments, the third slot segment 2214 may also extend along a curve, for example, the third slot segment 2214 is an arc segment.

[0378] Among them, the bottom wall of the first groove section 2212, the bottom wall of the second groove section 2213 and the bottom wall of the third groove section 2214 all form a first weak section 2211a, that is, the first weak portion 2211 includes three first weak sections 2211a, and the three first weak sections 2211a are respectively the bottom wall of the first groove section 2212, the bottom wall of the second groove section 2213 and the bottom wall of the third groove section 2214, and the three first weak sections 2211a constitute the first weak portion 2211.

[0379] A first weak section 2211a is formed in the area corresponding to the third slot section 2214, and the first weak portion 2211 includes three first weak sections 2211a. The second slot section 2213 connects the first slot section 2212 and the third slot section 2214. The first weak section 2211a formed in the area corresponding to the second slot section 2213 connects the first weak section 2211a formed in the area corresponding to the first slot section 2212 and the first weak section 2211a formed in the area corresponding to the third slot section 2214. When one of the first weak sections 2211a begins to rupture, it can drive the rupture of another first weak section 2211a, which is conducive to the rapid rupture of the first weak portion 2211 to open the predetermined pressure relief area P and achieve rapid pressure relief.

[0380] The first slot section 2212 and the third slot section 2214 are arranged opposite to each other, that is, the first slot section 2212 and the third slot section 2214 are spaced apart. For example, in FIG17 , the first slot section 2212 and the third slot section 2214 are spaced apart along the length direction Z of the first wall portion, and both the first slot section 2212 and the third slot section 2214 extend along the width direction Y of the first wall portion.

[0381] The second slot section 2213 connects the first slot section 2212 and the third slot section 2214. That is, the second slot section 2213 is located between the first slot section 2212 and the third slot section 2214, and the two ends of the second slot section 2213 are respectively connected to the first slot section 2212 and the third slot section 2214. For example, in FIG15 , the second slot section 2213 extends along the length direction Y of the wall portion. Of course, in other embodiments, the second slot section 2213 may also extend from the first slot section 2212 and the third slot section 2214 at its two ends in the length direction Y of the wall portion.

[0382] The first groove 221 is provided with a first groove section 2212 and a third groove section 2214 which are arranged opposite to each other, and a second groove section 2213 connecting the first groove section 2212 and the third groove section 2214, so that the pressure relief component 22 can split along the first groove section 2212, the second groove section 2213 and the third groove section 2214 when the battery cell 20 releases pressure, so as to open the predetermined pressure relief area P to release the internal pressure of the battery cell 20. The first groove 221 with such a structure makes the intersection position of the first groove section 2212 and the second groove section 2213 and the intersection position of the second groove section 2213 and the third groove section 2214 weaker, making it easier to split and open the predetermined pressure relief area P for pressure relief, and can further improve the pressure relief area and pressure relief rate of the battery cell 20.

[0383] As shown in Figure 17, in some embodiments, the position where the second slot segment 2213 is connected to the first slot segment 2212 deviates from the two ends of the first slot segment 2212, and the position where the second slot segment 2213 is connected to the third slot segment 2214 deviates from the two ends of the third slot segment 2214.

[0384] The position where the second slot segment 2213 connects to the first slot segment 2212 deviates from the two ends of the extending direction of the first slot segment 2212. The position where the second slot segment 2213 connects to the third slot segment 2214 deviates from the two ends of the extending direction of the third slot segment 2214.

[0385] Among them, the connection position of the first slot section 2212 and the second slot section 2213 deviates from the two ends of the first slot section 2212, that is, the second slot section 2213 is connected between the two ends of the first slot section 2212. Similarly, the connection position of the third slot section 2214 and the second slot section 2213 deviates from the two ends of the third slot section 2214, that is, the second slot section 2213 is connected between the two ends of the third slot section 2214, so that the shape of the first groove 221 formed by the first slot section 2212, the second slot section 2213 and the third slot section 2214 is an approximately "H"-shaped structure, and predetermined pressure relief areas P are formed on both sides of the second slot section 2213. Of course, the areas of the two predetermined pressure relief areas P may be the same or different.

[0386] Exemplarily, the second slot segment 2213 is a straight structure extending along the length direction Z of the first wall portion, the first slot segment 2212 and the third slot segment 2214 are both straight structures extending along the width direction Y of the first wall portion, and the second slot segment 2213 is located between the first slot segment 2212 and the third slot segment 2214 along the length direction Z of the first wall portion.

[0387] By setting the first slot section 2212, the second slot section 2213 and the third slot section 2214 to extend along a straight line, and setting the first slot section 2212 and the third slot section 2214 to be perpendicular to the second slot section 2213, so that the extension direction of the second slot section 2213 is the arrangement direction of the first slot section 2212 and the third slot section 2214, on the one hand, the regularity of the shape of the first groove 221 can be improved, which is conducive to reducing the processing difficulty of the first groove 221, thereby reducing the manufacturing cost of the battery cell 20. On the other hand, the two predetermined pressure relief areas P located on both sides of the second slot section 2213 relieve pressure in opposite directions when the battery cell 20 is relieved of pressure.

[0388] The position where the second groove section 2213 is connected to the first groove section 2212 deviates from the two ends of the first groove section 2212, so the connection position of the first groove section 2212 and the second groove section 2213 is set to be located between the two ends of the first groove section 2212, and the position where the second groove section 2213 is connected to the third groove section 2214 deviates from the two ends of the third groove section 2214, so the connection position of the third groove section 2214 and the second groove section 2213 is set to be located between the two ends of the third groove section 2214. The first groove section 2212, the second groove section 2213 and the third groove section 2214 form an "H"-shaped structure, so that predetermined pressure relief areas P can be formed on both sides of the second groove section 2213 of the first groove 221, and the two predetermined pressure relief areas P can be opened in a split manner for pressure relief when the battery cell 20 is pressure-relieved, which is beneficial to further increase the pressure relief effect of the battery cell 20 and can effectively improve the pressure relief rate of the battery cell 20.

[0389] The first groove 221 can also be other structures. Referring to Figure 9, the shape of the first groove 221 formed by the first groove section 2212, the second groove section 2213 and the third groove section 2214 can be a "U"-shaped structure, that is, one end of the second groove section 2213 is connected to one end of the first groove section 2212, and the other end is connected to one end of the third groove section 2214, so as to form a predetermined pressure relief area P on the pressure relief component 22.

[0390] In some embodiments, the first groove 221 further includes a fourth groove section 2215, which is arranged between the first groove section 2212 and the third groove section 2214. The first four groove sections are connected to the third groove section 2214, and the corresponding areas of the first four groove sections form a first weak section 2211a.

[0391] 17 , the fourth slot segment 2215 intersects the second slot segment 2213 at right angles. The fourth slot segment 2215 extends along the width direction Y of the first wall portion. Along the width direction Y of the first wall portion, the length of the fourth slot segment 2215 is less than the length of the first slot segment 2212, and the length of the fourth slot segment 2215 is less than the length of the third slot segment 2214.

[0392] The bottom walls of the first four trough sections form a first weak section 2211a. The bottom walls of the first trough section 2212, the second trough section 2213, the third trough section 2214 and the bottom walls of the first four trough sections together form a first weak portion 2211 including four first weak sections 2211a.

[0393] The arrangement of the fourth slot section 2215 facilitates the pressure relief component 22 to split from the intersection of the second slot section 2213 and the fourth slot section 2215, thereby enabling the two predetermined pressure relief areas P on both sides of the second slot section 2213 to open synchronously, thereby increasing the pressure relief rate.

[0394] Please continue to refer to Figure 17. In some embodiments, the first groove 221 defines two predetermined pressure relief areas P, and the two predetermined pressure relief areas P are respectively located on both sides of the second groove section 2213; the pressure relief component 22 also includes a second groove 222, and the second groove 222 is configured to guide the predetermined pressure relief area P to open. Each predetermined pressure relief area P is correspondingly provided with at least one second groove 222, and the first groove 221 is located between the two second grooves 222.

[0395] Each predetermined pressure relief area P may be provided with one second groove 222 or a plurality of second grooves 222 .

[0396] Each second groove 222 is configured to guide the corresponding predetermined pressure relief area P to flip when the groove bottom wall of the first groove 221 is broken, thereby guiding the predetermined pressure relief area P to open.

[0397] The second groove 222 extends in a direction parallel to the direction of extension of the second groove section 2213 of the first groove 221. The two second grooves 222 are spaced apart along the extending direction of the first groove section 2212 of the first groove 221. The first groove section 2212 and the third groove section 2214 of the first groove 221 are located between the two second grooves 222, and the second groove section 2213 is located between the two second grooves 222, so that the first groove 221 is located between the two second grooves 222.

[0398] Each first groove 221 is located between the edge of the first wall 211 and the first groove 221 along the width direction Y of the first wall. The two first grooves 221 separate the edge of the first wall 211 from the first groove 221 on both sides of the first groove 221 along the width direction Y of the first wall.

[0399] The second groove 222 can guide the corresponding predetermined pressure relief area P to open. At least one second groove 222 is correspondingly provided for each predetermined pressure relief area P, thereby improving the opening effect of each predetermined pressure relief area P of the pressure relief component 22, which is beneficial to increasing the pressure relief area of ​​the battery cell 20 after the predetermined pressure relief area P is opened, and further improving the pressure relief rate of the battery cell 20 when thermal runaway occurs, so as to reduce the risk of fire, explosion, connection failure, etc. caused by untimely pressure relief of the battery cell 20, and is beneficial to improving the reliability of the battery cell 20.

[0400] As shown in FIG. 17 , in some embodiments, the second slot segment 2213 and the second groove 222 are disposed opposite to each other along the first direction. Along the first direction, the first slot segment 2212 and the third slot segment 2214 are both spaced apart from the second groove 222 .

[0401] The second groove section 2213 and the second groove 222 are arranged opposite to each other along the first direction, and along the first direction, the first groove section 2212 and the third groove section 2214 are spaced apart from the second groove 222. Therefore, the first groove section 2212, the second groove section 2213 and the third groove section 2214 are not in contact with the second groove 222, which can reduce the mutual influence between the first groove 221 and the second groove 222 during the processing, and reduce the phenomenon that the area corresponding to the second groove 222 is cracked when the first groove 221 cracks and releases pressure, and can reduce the stress influence between the first groove 221 and the second groove 222. The second groove section 2213 and the second groove 222 are arranged opposite to each other along the first direction, and along the first direction, the first groove section 2212 and the third groove section 2214 are both spaced apart from the second groove 222, so that the second groove 222 is located between the edge of the first wall portion 211 along the first direction and the first notch. The second groove 222 can act as a buffer between the first groove 221 and the edge of the first wall portion 211 in the first direction, thereby reducing the risk of the first groove 221 cracking due to external force and improving the reliability of the battery cell 20.

[0402] The first direction may be different depending on the structure of the battery cell 20 . For example, in an embodiment where the first wall portion 211 is a rectangular wall portion, the first direction may be the length direction Z of the first wall portion or the width direction Y of the first wall portion.

[0403] In some embodiments, the first wall portion 211 is a rectangular wall portion, and the first direction is parallel to the width direction Y of the first wall portion.

[0404] That is, the first groove section 2212 and the third groove section 2214 extend along the width direction Y of the first wall, and the second groove 222 and the second groove section 2213 extend along the length direction Z of the first wall. The second groove 222 and the second groove section 2213 are arranged opposite to each other along the width direction Y of the first wall.

[0405] The first direction is parallel to the width direction Y of the first wall portion, and the second groove section 2213 and the second groove 222 are arranged opposite to each other along the width direction Y of the first wall portion. Along the width direction Y of the first wall portion, the first groove section 2212 and the third groove section 2214 are spaced apart from the second groove 222. The first groove section 2212, the second groove section 2213 and the third groove section 2214 are not in contact with the second groove 222 in the width direction Y of the first wall portion. This can reduce the mutual influence between the first groove 221 and the second groove 222 during the processing, and can reduce the phenomenon that the corresponding area of ​​the first groove 221 causes the corresponding area of ​​the second groove 222 to crack when the pressure is released, and can reduce the stress influence between the first groove 221 and the second groove 222. The second groove section 2213 and the second groove 222 are arranged opposite to each other along the width direction Y of the first wall portion, and along the width direction Y of the first wall portion, the first groove section 2212 and the third groove section 2214 are both spaced apart from the second groove 222, so that the second groove 222 is located between the edge of the first wall portion 211 along the width direction Y of the first wall portion and the first notch. The second groove 222 can act as a buffer between the first groove 221 and the edge of the first wall portion 211 in the first direction, thereby reducing the risk of the first groove 221 cracking due to external force and improving the reliability of the battery cell 20.

[0406] As shown in FIG. 21 , in other embodiments, the first groove section 2212 and the third groove section 2214 may also be arranged along the width direction Y of the first wall portion. Both the first groove section 2212 and the third groove section 2214 extend along the length direction Z of the first wall portion, and the second groove section 2213 extends along the width direction Y of the first wall portion and connects the first groove section 2212 and the third groove section 2214. The first groove 221 defines two predetermined pressure relief areas P, located on either side of the second groove section 2213 along the length direction Z of the first wall portion. Thus, the first groove 221 defines two side-by-side predetermined pressure relief areas P along the length direction Z of the first wall portion. The dimensions of the two predetermined pressure relief areas P along the length direction Z of the first wall portion are a1 and a2, respectively, where a = a1 + a2. The boundary between the two predetermined pressure relief areas P along the length direction Z of the first wall portion can be the centerline of the width direction of the second groove section 2213.

[0407] In some embodiments, as shown in FIG. 23 and FIG. 24 , along the thickness direction X of the first wall portion, the maximum groove depth of the first groove 221 is H1 , the thickness of the pressure relief component 22 is D, and 0.16≤H1 / D<1.

[0408] H1 / D can take any point value among 0.16, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 0.99, etc., or a range of values ​​between any two of them.

[0409] It is understood that if the pressure relief component 22 is integrally formed with the first wall portion 211, the first wall portion 211 can serve as the pressure relief component 22, and the thickness of the pressure relief component 22 is equal to the thickness of the first wall portion 211. The thickness of the first wall portion 211 can be the distance between the first surface 2111 and the second surface 2112 along the thickness direction X of the first wall portion.

[0410] In this embodiment, 0.16≤H1 / D<1, so that the maximum depth of the first groove 221 accounts for a small proportion of the thickness of the pressure relief component 22, and the bursting pressure of the battery cell 20 is not too high, which is conducive to improving the timeliness of the pressure relief of the battery cell 20.

[0411] In some embodiments, 0.4 mm ≤ H1 ≤ 2 mm, and 0.8 mm ≤ D ≤ 2.5 mm.

[0412] H1 can take any point value among 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, 1.8mm, 1.85mm, 1.9mm, 1.95mm, 2mm, etc., or any range value between any two of them.

[0413] D can be any point value among 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, 1.55mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, 1.8mm, 1.85mm, 1.9mm, 1.95mm, 2mm, 2.05mm, 2.1mm, 2.15mm, 2.2mm, 2.25mm, 2.3mm, 2.35mm, 2.4mm, 2.45mm, 2.5mm, etc., or a range value between any two of them.

[0414] In this embodiment, 0.4 mm ≤ H1 ≤ 2 mm, and 0.8 mm ≤ D ≤ 2.5 mm, keeping the maximum depth of the first groove 221 and the thickness of the pressure relief component 22 within a reasonable range, resulting in better economic efficiency. In an embodiment where the first wall 211 serves as the pressure relief component 22, the thickness of the first wall 211 is 0.8 mm to 2.5 mm. A thickness of 0.8 mm or greater ensures sufficient strength for the first wall 211. A thickness of 2 mm or less prevents excessive thickness. Given a given volume of the housing 21, the internal space of the housing 21 can be increased to create more space for the electrode assembly 23. While maintaining the thickness of the first wall 211 within the range of 0.8 mm to 2.5 mm, the maximum depth of the first groove 221 is controlled within the range of 0.4 mm to 2 mm, ensuring a better match between the maximum depth of the first groove 221 and the thickness of the pressure relief component 22, thereby ensuring good pressure relief capability for the pressure relief component 22.

[0415] The first groove 221 may be a primary scoring groove.

[0416] In some embodiments, the first groove 221 is a multi-level notch groove, which is a multi-level notch groove arranged in sequence along the direction from the first surface 2111 to the second surface 2112. In two adjacent notch grooves, the first-level notch groove away from the first surface 2111 is arranged at the bottom surface of the first-level notch groove close to the first surface 2111.

[0417] That is, the first groove 221 is a multi-step groove structure arranged along the thickness direction X of the first wall portion, that is, the first groove 221 is a step groove structure formed by multiple stamping operations.

[0418] For example, in Figures 22 to 27, the first groove 221 is a three-step groove structure. Of course, in other embodiments, the first groove 221 can also be a two-step groove, a four-step groove, a five-step groove or a six-step groove, etc.

[0419] It should be noted that in embodiments where the first groove 221 includes multiple groove segments, each groove segment is a multi-step groove structure. For example, in Figures 22-27, the first groove 221 includes a first groove segment 2212, a second groove segment 2213, and a third groove segment 2214. The corresponding first groove segment 2212, the second groove segment 2213, and the third groove segment 2214 are all multi-step groove structures. Of course, in the case where the first groove 221 as a whole is a structure such as a curve, a loop, or a straight line extending along a smooth trajectory, the first groove 221 as a whole is a multi-step groove structure. For example, referring to Figures 3 and 4, the first groove 221 is an annular structure. Accordingly, the first groove 221 as a whole is a multi-step groove structure.

[0420] By setting the first groove 221 as a stepped groove structure arranged along the thickness direction of the wall, so that the first groove 221 is a groove formed by multiple processing, when this structure is used to form grooves of the same depth in the pressure relief component 22, on the one hand, the depth of the single processing of the notched groove can be reduced, which is beneficial to reducing the manufacturing difficulty and demand for manufacturing equipment for forming grooves of the same depth, so as to reduce manufacturing costs, and can reduce the forming force that the pressure relief component 22 is subjected to during a single processing during the formation of the first groove 221, which is beneficial to reducing the risk of cracks in the pressure relief component 22, so as to improve the production quality of the battery cell 20, and on the other hand, it can improve the flow shape of the bottom wall of the first groove 221 during the formation process, which is beneficial to the flow of materials generated when forming the bottom wall of the first groove 221, so as to improve the consistency of the structure of the multi-stage notched groove.

[0421] In some embodiments, the first groove 221 is a three-level scoring groove, and the three-level scoring grooves are sequentially arranged from the first surface 2111 to the second surface 2112 .

[0422] The three-level scoring grooves defining the first groove 221 are the first sub-groove 221a, the second sub-groove 221b and the third sub-groove 221c, respectively. The first sub-groove 221a, the second sub-groove 221b and the third sub-groove 221c are arranged in sequence from the first surface 2111 to the second surface 2112. The second sub-groove 221b is arranged at the bottom surface of the first sub-groove 221a, and the third sub-groove 221c is arranged at the bottom surface of the second sub-groove 221b.

[0423] Exemplarily, as shown in Figures 22 to 27, in an embodiment where the first groove 221 includes a first groove segment 2212, a second groove segment 2213 and a third groove segment 2214, the first sub-groove 221a includes a first segment 221a1, a second segment 221a2 and a third segment 221a3, the second sub-groove 221b includes a fourth segment 221b1, a fifth segment 221b2 and a sixth segment 221b3, and the third sub-groove 221c includes a seventh segment 221c1, an eighth segment 221c2 and a ninth segment 221c3. The fourth section 221b1 is arranged on the bottom surface of the groove of the first section 221a1, the seventh section 221c1 is arranged on the bottom surface of the groove of the fourth section 221b1, and the first section 221a1, the fourth section 221b1 and the seventh section 221c1 together form a first groove section 2212; the fifth section 221b2 is arranged on the bottom surface of the groove of the second section 221a2, the eighth section 221c2 is arranged on the bottom surface of the groove of the fifth section 221b2, the second section 221a2, the fifth section 221b2 and the eighth section 221c2 together form a second groove section 2213; the sixth section 221b3 is arranged on the bottom surface of the groove of the third section 221a3, the ninth section 221c3 is arranged on the bottom surface of the groove of the sixth section 221b3, and the third section 221a3, the sixth section 221b3 and the ninth section 221c3 together form a third groove section 2214.

[0424] The first groove 221 is a three-level scoring groove. When forming grooves of the same depth, it can reduce the depth of the scoring groove in a single processing, which is beneficial to reducing the manufacturing difficulty and demand for manufacturing equipment for forming grooves of the same thickness, thereby reducing manufacturing costs. It can also reduce the forming force that the pressure relief component 22 is subjected to during a single processing during the formation of the bottom wall of the first groove 221, which is beneficial to reducing the risk of cracks in the pressure relief component 22, thereby improving the production quality of the battery cell 20. On the other hand, it can improve the flow morphology of the bottom wall of the first groove 221 during the formation process, which is beneficial to the flow of materials generated when forming the first groove 221, thereby improving the structural consistency of the multi-level scoring grooves; it also alleviates the problem of increased processing time due to multiple processing required for the formation of the first groove 221.

[0425] In some embodiments, the pressure relief component 22 is integrally formed with the first wall portion 211 .

[0426] That is to say, the pressure relief component 22 and the first wall portion 211 are an integrated structure, and the pressure relief component 22 and the first weak portion 2211 are arranged on the first wall portion 211 using an integrated molding process, that is, the pressure relief component 22 is the first wall portion 211, so that the pressure relief component 22 is a part of the outer shell 21.

[0427] For example, in Figure 10 , the first wall portion 211 is the bottom wall of the housing 212, disposed opposite the end cap 213 in the thickness direction X of the first wall portion. The pressure relief component 22 is the bottom wall, and the first groove 221 is disposed on the bottom wall. If the first wall portion 211 is the end cap 213, the pressure relief component 22 is the end cap 213, so that the pressure relief component 22 can close the opening 2121 of the housing 212, and both electrode terminals 24 are mounted on the pressure relief component 22.

[0428] By setting the pressure relief component 22 and the first wall portion 211 as an integrally formed structure, the pressure relief component 22 is a structure integrated on the first wall portion 211, that is, the pressure relief component 22 is a wall of the outer shell 21, and correspondingly, the pressure relief component 22 is provided on the first wall portion 211. The battery cell 20 adopting this structure can improve the structural strength of the pressure relief component 22 provided on the first wall portion 211, and can reduce the risk of leakage between the pressure relief component 22 and the first wall portion 211 due to improper assembly.

[0429] In some embodiments, the pressure relief component 22 is made of aluminum alloy.

[0430] It is understood that in embodiments where the pressure relief component 22 and the first wall portion 211 are integrally formed, the material of the first wall portion 211 includes an aluminum alloy. If the first wall portion 211 is an end cap 213, the end cap 213 may be made of an aluminum alloy; if the first wall portion 211 is a wall portion within the housing 212, the housing 212 may also be made of an aluminum alloy.

[0431] Aluminum alloy is lightweight and ductile, making it easier to form the first groove 221 on the pressure relief component 22. In the embodiment where the pressure relief component 22 and the first wall portion 211 are integrally formed, the first wall portion 211 is made of aluminum alloy, which can effectively reduce the difficulty of forming the first wall portion 211.

[0432] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other individual elements ≤ 0.03%.

[0433] This aluminum alloy belongs to the third series aluminum, has lower hardness and better forming ability, reduces the difficulty of processing the first groove 221, is conducive to improving the processing accuracy of the first groove 221, and improves the pressure relief consistency of the pressure relief component 22.

[0434] In some embodiments, the aluminum alloy includes the following components in mass percentage: aluminum ≥ 96.7%, 0.05% ≤ copper ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other individual element components ≤ 0.05%, and the total composition of other elements ≤ 0.15%.

[0435] This aluminum alloy belongs to the fifth series aluminum. The pressure relief component 22 made of this aluminum alloy has higher hardness, greater strength and good anti-destruction ability.

[0436] In some embodiments, the pressure relief component 22 is separately provided from the first wall portion 211 . The first wall portion 211 is provided with a pressure relief hole (not shown in the figure). The pressure relief component 22 is installed on the first wall portion 211 and covers the pressure relief hole.

[0437] The pressure relief hole passes through both sides of the first wall portion in the thickness direction X, and the pressure relief hole is communicated with the interior of the housing 21 .

[0438] The pressure relief component 22 and the first wall portion 211 are provided separately. This means that before the pressure relief component 22 and the first wall portion 211 are assembled, the pressure relief component 22 and the first wall portion 211 are two separate components. To complete the assembly of the pressure relief component 22 and the first wall portion 211, the pressure relief component 22 and the first wall portion 211 need to be connected to form a whole. The pressure relief component 22 can be connected to the hole wall of the pressure relief hole and cover the pressure relief hole. For example, the pressure relief component 22 is welded to the first wall portion 211.

[0439] By arranging the pressure relief component 22 and the first wall portion 211 as a separate structure, the pressure relief component 22 is a structure installed on the first wall portion 211. The battery cell 20 adopting this structure can reduce the difficulty of setting the pressure relief component 22 on the first wall portion 211, and the processing steps of the outer shell 21 and the processing steps of the pressure relief component 22 can be carried out simultaneously, which is conducive to optimizing the production rhythm of the battery cell 20.

[0440] In some embodiments, the battery cell 20 includes an electrode assembly 23 . The electrode assembly 23 is accommodated in the housing 21 , and the first wall portion 211 supports the electrode assembly 23 .

[0441] The battery cell 20 may include one or more electrode assemblies 23. In an embodiment where the battery cell 20 includes a plurality of electrode assemblies 23, the plurality of electrode assemblies 23 are stacked along a thickness direction thereof.

[0442] The first wall portion 211 supports the electrode assembly 23 . It can be understood that the first wall portion 211 bears the weight of the electrode assembly 23 .

[0443] The first wall portion 211 supports the electrode assembly 23 , and the pressure relief component 22 is disposed on the first wall portion 211 , which can reduce the risk of substances released when the battery cell 20 releases pressure acting on other electrical connection structures, thereby reducing the risk of causing other reliability issues.

[0444] In some embodiments, the battery cell 20 includes an electrode terminal 24 , which is disposed on other walls of the housing 21 except the first wall 211 .

[0445] The electrode terminal 24 is provided on other walls of the housing 21 except the first wall portion 211 . That is, the electrode terminal 24 and the pressure relief member 22 are provided on different walls of the housing 21 .

[0446] The electrode terminal 24 is arranged on other walls of the shell 21 except the first wall portion 211, so the risk of the substance discharged from the battery cell 20 when the pressure is released acts on the electrode terminal 24 is low, which can reduce the risk of the battery cell 20 short-circuiting due to the substance discharged from the battery cell 20 when the pressure is released and the electrode terminal 24 forming an electrical connection, causing the battery cell 20 to short-circuit and cause thermal runaway of the battery cell 20 again.

[0447] In some embodiments, the electrode terminal 24 is disposed on a wall of the housing 21 opposite to the first wall portion 211 .

[0448] Exemplarily, the housing 212 of the outer shell 21 has a bottom wall opposite to the opening 2121. The end cap 213 covers the opening 2121 and is disposed opposite the bottom wall. The bottom wall is the first wall portion 211, and the electrode terminal 24 is disposed on the end cap 213 covering the opening 2121.

[0449] The electrode terminal 24 is arranged on the wall of the shell 21 opposite to the first wall 211, so that the distance between the electrode terminal 24 and the pressure relief component 22 is farther, which can further reduce the risk of the discharged substance of the battery cell 20 acting on the electrode terminal 24 when the pressure is released, and further reduce the risk of the battery cell 20 short-circuiting due to the formation of electrical connection between the discharged substance and the electrode terminal 24 when the pressure is released, causing the battery cell 20 to short-circuit again and cause thermal runaway of the battery cell 20.

[0450] In some embodiments, the housing 21 includes a shell 212 and an end cover 213 ; the shell 212 has at least one opening 2121 ; the end cover 213 corresponds one-to-one to the opening 2121 , and the end cover 213 is connected to the shell 212 and closes the opening 2121 ; wherein at least one end cover 213 is the first wall portion 211 .

[0451] The end cap 213 is the first wall portion 211, that is, the pressure relief component 22 is disposed on the end cap 213. In an embodiment where the housing 212 has two opposing openings 2121, the housing 21 includes two end caps 213. One of the two end caps 213 can be the first wall, that is, one end cap 213 is provided with the pressure relief component 22, or both end caps 213 can be the first wall, that is, both end caps 213 are provided with the pressure relief component 22.

[0452] By setting the first wall portion 211 of the shell 21 as the end cover 213 of the shell 21 for closing the opening 2121, the battery cell 20 with this structure is convenient for setting the pressure relief component 22 on the end cover 213, which is beneficial to reducing the manufacturing difficulty of the battery cell 20 and improving the production efficiency of the battery cell 20.

[0453] 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, as shown in Figures 3 and 4, the outer shell 21 may include a shell 212 and an end cover 213. The interior of the shell 212 forms a accommodating cavity with an opening 2121, which is used to accommodate the electrode assembly 23. The end cover 213 closes the opening 2121, and the shell 212 includes a first wall portion 211.

[0454] The shell 212 may include an integrally formed side wall and bottom wall, that is, the shell 212 is manufactured using an integral molding process, such as an integral molding process such as stamping, casting or extrusion molding. In other words, the side wall and bottom wall of the shell 212 are an integral structure.

[0455] The housing 212 includes a first wall portion 211. That is, the first wall portion 211 is a wall of the housing 212. For example, in FIG10 , the first wall portion 211 is a bottom wall of the housing 212 disposed opposite the end cap 213 in the thickness direction X of the first wall portion. Of course, in other embodiments, the first wall portion 211 may also be a side wall of the housing 212.

[0456] By setting the first wall portion 211 of the outer shell 21 as a wall portion of the shell 212, the battery cell 20 adopting this structure can make the area of ​​the outer shell 21 where the pressure relief component 22 is provided away from the end cover 213, thereby effectively alleviating the stress generated by the connection between the end cover 213 and the shell 212 acting on the pressure relief component 22, thereby reducing the impact on the predetermined pressure relief area P of the pressure relief component 22 and the corresponding area of ​​the first groove 221, and further helping to reduce the risk of cracking or structural strength reduction of the pressure relief component 22 under the pulling action of stress, thereby improving the service life and reliability of the battery cell 20.

[0457] It should be noted that the structure of the battery cell 20 can be various. In some embodiments, the shell 212 has two openings 2121 arranged opposite to each other; the outer shell 21 includes two end covers 213, each end cover 213 is connected to the shell 212 and closes an opening 2121, and the shell 212 includes a first wall portion 211.

[0458] The housing 212 defines an interior housing cavity, and both openings 2121 communicate with the housing cavity. The two openings 2121 may be arranged relative to each other along the thickness direction X of the first wall portion. In an embodiment where the housing 21 includes two openings 2121 and two end caps 213 , the first wall portion 211 may also be a wall of the housing 212 .

[0459] The shell 212 of the outer casing 21 has two openings 2121 arranged opposite each other, and the two end caps 213 respectively seal the two openings 2121. This structure of the battery cell 20 facilitates assembly of the battery cell 20 from both ends of the shell 212, thereby reducing the difficulty in manufacturing and assembling the battery cell 20. The shell 212 includes a first wall portion 211, and the pressure relief component 22 is not provided on the end cap 213. This can reduce the risk of substances released from the battery cell 20 during pressure relief from the battery cell 20 interacting with other structures of the battery 100. This further reduces the risk of substances released from the battery cell 20 during pressure relief from the battery cell 20 interacting with the electrode terminals 24 to form an electrical connection, thereby causing a short circuit in the battery cell 20 and further leading to thermal runaway of the battery cell 20.

[0460] In the embodiment where the housing 21 includes two openings 2121 and two end covers 213, the two end covers 213 respectively close the two openings 2121, and one of the two end covers 213 is a first wall portion 211. Of course, both end covers 213 may be first wall portions 211, and each first wall portion 211 may be provided with a pressure relief component 22.

[0461] In some embodiments, the housing 212 has an opening 2121 , and a wall portion of the housing 212 opposite to the opening 2121 is the first wall portion 211 .

[0462] Illustratively, the wall of the housing 212 opposite to the opening 2121 is the bottom wall of the housing 212 , the bottom wall is the first wall 211 , the end cover 213 is disposed opposite to the first wall 211 , and the electrode terminal 24 is disposed on the end cover 213 .

[0463] The wall portion of the shell 212 that is arranged opposite to the opening 2121 is the first wall portion 211, which can reduce the risk of the substance discharged from the battery cell 20 when the pressure is released to act on other structures of the battery 100, thereby further reducing the risk of the battery cell 20 short-circuiting due to the substance discharged from the battery cell 20 when the pressure is released to form an electrical connection with the electrode terminal 24, causing the battery cell 20 to short-circuit and cause thermal runaway of the battery cell 20 again.

[0464] In some embodiments, the pressure relief component 22 is made of steel.

[0465] The steel material can be carbon steel, alloy steel, stainless steel, etc.

[0466] It is understood that in the embodiment where the pressure relief component 22 and the first wall portion 211 are integrally formed, the material of the first wall portion 211 includes steel. If the first wall portion 211 is an end cap 213, the end cap 213 can be made of steel; if the first wall portion 211 is a wall portion in the housing 212, the housing 212 can be made of steel.

[0467] In this embodiment, steel has the characteristic of high strength, and the pressure relief component 22 made of steel has greater strength. Under the condition of a constant burst pressure of the battery cell 20, the pressure relief component 22 can be made thinner, thereby reducing the volume of the pressure relief component 22. In the embodiment where the pressure relief component 22 is integrally formed with the first wall portion 211, the first wall portion 211 is made of steel and can be made thinner. Under the condition of a constant volume of the outer shell 21, the volume of the outer shell 21 can be increased to provide more space for the electrode assembly 23, which is conducive to improving the volumetric energy density of the battery cell 20.

[0468] In some embodiments, the steel material is carbon steel or stainless steel.

[0469] Carbon steel can be low carbon steel, medium carbon steel or high carbon steel.

[0470] In some embodiments, the pressure relief component 22 is made of aluminum alloy.

[0471] It is understood that in embodiments where the pressure relief component 22 and the first wall portion 211 are integrally formed, the material of the first wall portion 211 includes an aluminum alloy. If the first wall portion 211 is an end cap 213, the end cap 213 may be made of an aluminum alloy; if the first wall portion 211 is a wall portion within the housing 212, the housing 212 may also be made of an aluminum alloy.

[0472] Aluminum alloy is lightweight and ductile, making it easier to form the first and second grooves 221 and 222 in the pressure relief component 22. In embodiments where the pressure relief component 22 and the first wall portion 211 are integrally formed, the first wall portion 211 is made of aluminum alloy, effectively reducing the difficulty of forming the first wall portion 211. Due to the excellent ductility of aluminum alloy, it is easier to deposit material in the predetermined pressure relief area P when forming the first groove 221.

[0473] In some embodiments, the present application further provides a battery 100 , which includes the battery cell 20 provided in any of the above embodiments.

[0474] As shown in FIG. 2 , the battery 100 may further include a box body 10 , in which the battery cells 20 are accommodated.

[0475] In some embodiments, the box body 10 may include a first box body 11 and a second box body 12 . The first box body 11 and the second box body 12 cover each other, and the first box body 11 and the second box body 12 jointly define an assembly space for accommodating the battery cells 20 .

[0476] 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, and the first box body 11 covers the open side of the second box body 12, so that the first box body 11 and the second box body 12 jointly define an assembly space; the first box body 11 and the second box body 12 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.

[0477] Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder or a rectangular parallelepiped, etc. For example, in FIG2 , the box body 10 is a rectangular parallelepiped structure.

[0478] Optionally, the number of battery cells 20 disposed in the housing 10 may be one or more. For example, in FIG2 , the housing 10 of the battery 100 includes multiple battery cells 20, which may be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a configuration in which multiple battery cells 20 are connected in both series and parallel. Multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 20 is housed in the housing 10. Alternatively, the battery 100 may be a module formed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid configuration, and then the multiple battery modules 100 are then connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed in the housing 10.

[0479] The battery 100 may further include other structures. For example, the battery 100 may further include a busbar component that connects the plurality of battery cells 20 to achieve electrical connection between the plurality of battery cells 20 .

[0480] It should be noted that in some embodiments, the battery 100 may not be provided with a housing 10. The battery 100 includes multiple battery cells 20, and the battery 100 composed of multiple battery cells 20 can be directly assembled on an electrical device to provide electrical energy to the electrical device through the multiple battery cells 20. In other words, the housing 10 can serve as part of the electrical device. Taking the vehicle 1000 as an example of an electrical device, the housing 10 can serve as part of the chassis structure of the vehicle 1000. For example, a portion of the housing 10 can form at least a portion of the floor of the vehicle 1000, or a portion of the housing 10 can form at least a portion of the crossbeam or longitudinal beam of the vehicle 1000.

[0481] In some embodiments, the present application further provides an electrical device, which includes the battery cell 20 provided in any of the above embodiments.

[0482] The battery cell 20 is used to provide power to an electrical device, wherein the electrical device can be any of the aforementioned devices or systems using the battery cell 20 .

[0483] The present application provides a battery cell 20, which includes a housing 21, an electrode assembly 23, and a pressure relief component 22. The housing 21 has a first wall portion 211, and includes a shell 212 and an end cap 213. The interior of the shell 212 forms a receiving cavity with an opening 2121, and the electrode assembly 23 is received in the receiving cavity. The end cap 213 closes the opening 2121, and the end cap 213 serves as the first wall portion 211. The pressure relief component 22 is integrally formed with the first wall portion 211 and is disposed on the first wall portion 211.

[0484] Along the thickness direction X of the first wall portion, the first wall portion 211 has a first surface 2111 and a second surface 2112 that are oppositely disposed. The first surface 2111 is located on the side of the first wall portion 211 facing away from the interior of the housing 21, while the second surface 2112 is located on the side of the first wall portion 211 facing the interior of the housing 21. The pressure relief component 22 is provided with a first groove 221. The first groove 221 is a three-level scored groove arranged sequentially from the first surface 2111 to the second surface 2112. The first groove 221 defines two predetermined pressure relief areas P. The pressure relief component 22 is configured to rupture along at least a portion of the first groove 221 when pressure is released from the battery cell 20. The second surface 2112 is provided with a second groove 222. Along the thickness direction X of the first wall portion, the bottom wall of the second groove 222 is thicker than the bottom wall of the first groove 221. The second groove 222 is configured to guide the predetermined pressure relief areas P to flip when the first groove 221 ruptures, thereby releasing internal pressure from the battery cell 20. The pressure relief component 22 and the first wall portion 211 are integrally formed.

[0485] The first groove 221 includes a first groove section 2212, a second groove section 2213, a third groove section 2214, and a fourth groove section 2215. The first groove section 2212, the second groove section 2213, the third groove section 2214, and the fourth groove section 2215 each form a first weak section 2211a. The first groove section 2212 and the third groove section 2214 are spaced apart from each other along the length direction Z of the first wall portion. Both the first groove section 2212 and the third groove section 2214 extend in a straight line along the width direction Y of the first wall portion. The third groove section 2214 extends in a straight line along the length direction Z of the first wall portion. The second groove section 2213 connects the first groove section 2212 and the third groove section 2214. The connection between the second groove section 2213 and the first groove section 2212 is located between the two ends of the first groove section 2212, and the connection between the second groove section 2213 and the third groove section 2214 is located between the two ends of the third groove section 2214. The first, second, and third groove sections 2212, 2213, and 2214 form an H-shaped first groove 221. Along the width direction Y of the first wall, a predetermined pressure relief area P is formed on either side of the second groove section 2213. The first groove 221 defines two predetermined pressure relief areas P. The fourth groove section 2215 is located between the first and third groove sections 2212, 2214, and intersects with the second groove section 2213.

[0486] The sum of the areas S1 of all the predetermined pressure relief zones P is 0.03 to 0.3 times the area S2 of the first surface 2111. 2 ≤S1≤1300mm 2 ;5000mm 2 ≤S2≤8500mm 2 .

[0487] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, comprising: A housing including a first wall portion, which has a first surface and a second surface oppositely arranged in the thickness direction of the first wall portion; A pressure relief component disposed on the first wall portion, the pressure relief component is provided with a first groove, the first groove is recessed from the first surface towards the direction close to the second surface, the first groove defines at least one predetermined pressure relief area, and the pressure relief component is configured to be able to crack along at least part of the first groove when the battery cell relieves pressure; Wherein, the sum S1 of the areas of all the predetermined pressure relief areas is 0.03 times to 0.3 times of the area S2 of the first surface.

2. The battery cell according to claim 1, wherein 500mm 2 ≤S1≤1300mm 2 。 3. The battery cell according to claim 1 or 2, wherein 5000mm 2 ≤S2≤8500mm 2 。 4. The battery cell according to any one of claims 1-3, wherein, The first wall portion is a rectangular wall portion; In the width direction of the first wall portion, the size of the first surface is c; in the length direction of the first wall portion, the size of the first surface is d, and S2 = c * d; Wherein, 55mm ≤ c ≤ 85mm; 100mm ≤ d ≤ 260mm.

5. The battery cell according to any one of claims 1-4, wherein, The first wall portion is a rectangular wall portion; In the length direction of the first wall portion, the pressure relief component forms at least one predetermined pressure relief area, and the sum a of the sizes of all the predetermined pressure relief areas arranged in the length direction of the first wall portion is 0.1 times to 0.5 times of the size d of the first surface in the length direction of the first wall portion.

6. The battery cell according to any one of claims 1-5, wherein, The first wall portion is a rectangular wall portion; In the width direction of the first wall portion, the first groove defines at least one predetermined pressure relief area, and the sum b of the sizes of all the predetermined pressure relief areas arranged in the width direction of the first wall portion is 0.3 times to 0.7 times of the size c of the first surface in the width direction of the first wall portion.

7. The battery cell according to any one of claims 1-6, wherein, The first wall portion is a rectangular wall portion; In the length direction of the first wall portion, the pressure relief component forms at least one predetermined pressure relief area, and the sum of the sizes of all the predetermined pressure relief areas arranged in the length direction of the first wall portion is a, and 26mm ≤ a ≤ 50mm.

8. The battery cell according to any one of claims 1-7, wherein, The first wall portion is a rectangular wall portion; In the width direction of the first wall portion, the first groove defines at least one predetermined pressure relief area, and the sum b of the sizes of all the predetermined pressure relief areas arranged in the width direction of the first wall portion is 18mm ≤ b ≤ 62mm.

9. The battery cell according to any one of claims 1-8, wherein, The first wall portion is a rectangular wall portion; In the length direction of the first wall portion, the pressure relief component forms at least one predetermined pressure relief area, and the sum of the sizes of all the predetermined pressure relief areas arranged in the length direction of the first wall portion is a; In the width direction of the first wall portion, the first groove defines at least one predetermined pressure relief area, and the sum of the sizes of all the predetermined pressure relief areas arranged in the width direction of the first wall portion is b, and in the width direction of the first wall portion, the size of the first surface is c; When 10mm ≤ c ≤ 40mm, the sum a of the sizes of all the predetermined pressure relief areas arranged in the length direction of the first wall portion is 2 times to 3 times of the sum b of the sizes of all the predetermined pressure relief areas arranged in the width direction of the first wall portion; When 40mm < c ≤ 60mm, the sum a of the dimensions of all the predetermined pressure relief zones arranged along the length direction of the first wall portion is 1 to 2 times the sum b of the dimensions of all the predetermined pressure relief zones arranged along the width direction of the first wall portion; When 60mm < c, the sum a of the dimensions of all the predetermined pressure relief zones arranged along the length direction of the first wall portion is 0.4 to 1 times the sum b of the dimensions of all the predetermined pressure relief zones arranged along the width direction of the first wall portion.

10. The battery cell according to any one of claims 1-9, wherein, The pressure relief component further includes a second groove configured to guide the opening of the predetermined pressure relief zone.

11. The battery cell according to claim 10, wherein, The second groove is recessed from the second surface towards the direction close to the first surface.

12. The battery cell according to claim 10 or 11, wherein, The first surface is the surface of the pressure relief component facing away from the interior of the housing, and the second surface is the surface of the pressure relief component facing the interior of the housing.

13. The battery cell according to any one of claims 10-12, wherein, The first groove and the second groove do not contact each other.

14. The battery cell according to any one of claims 1-13, wherein, The first groove includes a first groove segment and a second groove segment, the first groove segment and the second groove segment are connected, and the first groove segment and the second groove segment jointly define at least one of the predetermined pressure relief zones.

15. The battery cell according to claim 14, wherein, The first groove further includes a third groove segment, the first groove segment and the third groove segment are arranged opposite to each other, the second groove segment connects the first groove segment and the third groove segment, and the first groove segment, the second groove segment and the third groove segment jointly define at least one of the predetermined pressure relief zones.

16. The battery cell according to claim 15, wherein, The position where the second groove segment is connected to the first groove segment deviates from both ends of the first groove segment, and the position where the second groove segment is connected to the third groove segment deviates from both ends of the third groove segment.

17. The battery cell according to claim 15 or 16, wherein, The first groove defines two of the predetermined pressure relief zones, and the two predetermined pressure relief zones are respectively located on both sides of the second groove segment; The pressure relief component further includes a second groove configured to guide the opening of the predetermined pressure relief zone, at least one of the second grooves is correspondingly arranged for each of the predetermined pressure relief zones, and the first groove is located between the two second grooves.

18. The battery cell according to claim 17, wherein, The second groove segment is arranged opposite to the second groove along a first direction, and along the first direction, both the first groove segment and the third groove segment are spaced from the second groove.

19. The battery cell according to claim 18, wherein, The first wall portion is a rectangular wall portion, and the first direction is parallel to the width direction of the first wall portion.

20. The battery cell according to any one of claims 1-19, wherein, The first groove is a multi-stage scoring groove, which is a multi-stage scoring groove arranged in sequence from the first surface to the second surface. Among two adjacent stages of the scoring grooves, the scoring groove of the stage farther from the first surface is arranged on the groove bottom surface of the scoring groove of the stage closer to the first surface.

21. The battery cell according to claim 20, wherein, The first groove is a three-stage scoring groove, and the three-stage scoring groove is arranged in sequence from the first surface to the second surface.

22. The battery cell according to any one of claims 1-21, wherein, The pressure relief component is integrally formed with the first wall portion.

23. The battery cell according to any one of claims 1-22, wherein, The pressure relief component is separately arranged from the first wall portion, the first wall portion is provided with a pressure relief hole, and the pressure relief component is installed on the first wall portion and covers the pressure relief hole.

24. The battery cell according to any one of claims 1-23, wherein, The battery cell includes an electrode assembly, the electrode assembly is accommodated in the housing, and the first wall portion supports the electrode assembly.

25. The battery cell according to any one of claims 1-24, wherein, The battery cell includes electrode terminals, and the electrode terminals are disposed on other wall portions of the housing except the first wall portion.

26. The battery cell according to claim 25, wherein, The electrode terminals are disposed on the wall of the housing opposite to the first wall portion.

27. The battery cell according to any one of claims 1-26, wherein, The housing includes: a housing body having at least one opening; end caps corresponding to the openings one by one, the end caps being connected to the housing body and closing the openings; wherein at least one of the end caps is the first wall portion, or the housing body includes the first wall portion.

28. The battery cell according to claim 27, wherein, The housing body has two openings arranged oppositely; the housing includes two end caps, each end cap being connected to the housing body and closing one of the openings, and the housing body includes the first wall portion.

29. The battery cell according to claim 27, wherein, The housing body has one opening, and the wall portion of the housing body opposite to the opening is the first wall portion.

30. The battery cell according to any one of claims 1-29, wherein, The material of the pressure relief component includes steel material.

31. The battery cell according to claim 30, wherein, The steel material is carbon steel or stainless steel.

32. The battery cell according to any one of claims 1-29, wherein, The material of the pressure relief component includes aluminum alloy.

33. The battery cell according to claim 32, wherein, The aluminum alloy includes components with the following mass percentage contents: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other single elements ≤ 0.03%.

34. The battery cell according to claim 32, wherein, The aluminum alloy includes components with the following mass percentage contents: aluminum ≥ 96.7%, 0.05% ≤ copper ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other single element components ≤ 0.05%, and the total content of other elements ≤ 0.15%.

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

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

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