Battery monomer, battery and electric device

Abstract

The utility model provides a battery monomer, a battery and a power utilization device, and belongs to the technical field of batteries. Wherein the battery monomer comprises a shell, an electrode terminal and an electrode assembly. The housing has a first wall. The electrode terminal is arranged on the first wall. The electrode assembly is accommodated in the housing, and the electrode assembly is electrically connected with the electrode terminal. The first wall is provided with a pressure relief groove, the first wall is configured to be capable of cracking along at least part of the pressure relief groove when the battery monomer is subjected to pressure relief, the projection of the pressure relief groove is not overlapped with the projection of the electrode terminal in the thickness direction of the first wall, and the thickness of the electrode terminal is greater than that of the first wall. The structural rigidity of the first wall can be improved through the electrode terminal, so that the deformation resistance of the first wall is improved, the strain and strain amplitude of the area, provided with the pressure relief grooves, of the first wall in the using process can be reduced, the phenomenon of low-cycle fatigue of the area, provided with the pressure relief grooves, of the first wall can be reduced, and the service life of the first wall is prolonged. And the risk of early valve opening of the single battery is reduced.

Description

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] In recent years, new energy vehicles have developed by leaps and bounds. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also growing. Among them, batteries, as core components of new energy vehicles, have high requirements in terms of reliability and service life.

[0003] In battery technology, in order to ensure the safety of battery cells, a pressure relief structure for releasing the internal pressure of the battery cells is generally provided on the outer shell of the battery cells, so that when the internal pressure or temperature of the battery cells reaches a threshold value, the pressure relief structure can be actuated to release the internal pressure of the battery cells. However, the pressure relief structure of the existing battery cells often actuates the valve to open in advance during use, resulting in poor stability in the use of the battery cells, which is not conducive to improving the service life and reliability of the battery cells. Utility Model Content

[0004] The embodiments of the present application provide a battery cell, a battery, and an electrical device, which can effectively improve the service life and reliability of the battery cell.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, comprising a shell, an electrode terminal and an electrode assembly; the shell has a first wall; the electrode terminal is arranged on the first wall; the electrode assembly is accommodated in the shell, and the electrode assembly is electrically connected to the electrode terminal; wherein the first wall is provided with a pressure relief groove, and the first wall is configured to be able to split along at least a portion of the pressure relief groove when the battery cell is depressurized, and along the thickness direction of the first wall, the projection of the pressure relief groove does not overlap with the projection of the electrode terminal, and the thickness of the electrode terminal is greater than the thickness of the first wall.

[0006] In the above technical solution, a pressure relief groove is provided on the first wall, so that the first wall can be split along at least part of the pressure relief groove when the battery cell releases pressure, so as to release the internal pressure of the battery cell, wherein, by also assembling the electrode terminal on the first wall, the thickness of the electrode terminal in the thickness direction of the first wall is greater than the thickness of the first wall, and the projection of the electrode terminal in the thickness direction of the first wall does not overlap with the projection of the pressure relief groove in the thickness direction of the first wall, so that the battery cell of this structure can set the electrode terminal and the pressure relief structure of the battery cell on the same wall of the outer shell, so that the structural stiffness of the first wall can be improved through the electrode terminal to improve the deformation resistance of the first wall, so that the deformation phenomenon of the first wall can be alleviated during the use of the battery cell, so as to reduce the strain and strain amplitude of the area of ​​the first wall where the pressure relief groove is provided, and then the phenomenon of low-cycle fatigue in the area of ​​the first wall where the pressure relief groove is provided can be reduced, so as to reduce the phenomenon of fatigue damage in the area of ​​the first wall where the pressure relief groove is provided, which is beneficial to reduce the risk of premature valve opening of the battery cell, so as to improve the service life and reliability of the battery cell.

[0007] In some embodiments, the pressure relief groove and the electrode terminal are arranged along a first direction; wherein, along a second direction, the maximum dimension of the electrode terminal is D 1 , the maximum dimension of the first wall is D 2 , satisfying, 0.4≤D 1 / D 2 ≤0.9, the thickness direction of the first wall, the first direction and the second direction are perpendicular to each other.

[0008] In the above technical solution, the ratio of the maximum dimension of the electrode terminal in the second direction to the maximum dimension of the first wall in the second direction is 0.4 to 0.9. On the one hand, by setting the ratio of the maximum dimension of the electrode terminal in the second direction to the maximum dimension of the first wall in the second direction to be greater than or equal to 0.4, the space occupied by the electrode terminal in the second direction of the first wall can be increased, which is beneficial to enhancing the reinforcing effect of the electrode terminal on the structural rigidity of the first wall, so as to improve the deformation resistance of the first wall, so that the deformation phenomenon of the first wall can be alleviated during the use of the battery cell, so as to reduce the strain and strain amplitude of the area where the pressure relief groove is provided on the first wall, thereby reducing the occurrence of low-cycle fatigue in the area where the pressure relief groove is provided on the first wall. The phenomenon is beneficial to reduce the risk of premature valve opening in the battery cell, so as to improve the service life and reliability of the battery cell. On the other hand, by setting the ratio of the maximum dimension of the electrode terminal in the second direction to the maximum dimension of the first wall in the second direction to be less than or equal to 0.9, the phenomenon that the electrode terminal occupies too much space on the first wall in the second direction can be alleviated, so as to reduce the phenomenon that the opening of the mounting hole for installing the electrode terminal is too large, thereby reducing the difficulty of assembling the electrode terminal and the difficulty of manufacturing the mounting hole, so as to reduce the difficulty of manufacturing the battery cell, and can alleviate the phenomenon that the structural strength of the area where the mounting hole is set on the first wall is too low, so as to reduce the risk of breakage or damage of the first wall during processing or use.

[0009] In some embodiments, along the second direction, the maximum dimension of the electrode terminal is D 1 , the maximum dimension of the first wall is D 2 , satisfying, 0.6≤D 1 / D 2 ≤0.9.

[0010] In the above technical solution, by further setting the ratio of the maximum dimension of the electrode terminal in the second direction to the maximum dimension of the first wall in the second direction to be greater than or equal to 0.6, the space occupied by the electrode terminal in the second direction of the first wall can be further increased, which is beneficial to further enhance the reinforcing effect of the electrode terminal on the structural rigidity of the first wall, so as to enhance the deformation resistance of the first wall, so that the deformation of the first wall can be further alleviated during the use of the battery cell, so as to reduce the strain and strain amplitude of the area of ​​the first wall where the pressure relief groove is provided, and further reduce the phenomenon of low-cycle fatigue in the area of ​​the first wall where the pressure relief groove is provided, which is beneficial to further reduce the risk of premature valve opening of the battery cell, so as to enhance the service life and reliability of the battery cell.

[0011] In some embodiments, the outer edge of the first wall includes a first edge, and the first edge and the pressure relief groove are respectively located on both sides of the electrode terminal in a first direction, and the first direction is perpendicular to the thickness direction of the first wall; wherein along the first direction, the minimum distance between the pressure relief groove and the electrode terminal is L 1 , the minimum distance between the pressure relief groove and the first edge is L 2 , satisfying, 0.2≤L 1 / L 2 ≤0.8.

[0012] In the above technical solution, the ratio of the minimum distance between the pressure relief groove and the electrode terminal in the first direction to the minimum distance between the pressure relief groove and the first edge in the first direction is 0.2 to 0.8. On the one hand, by setting the ratio of the minimum distance between the pressure relief groove and the electrode terminal in the first direction to the minimum distance between the pressure relief groove and the first edge in the first direction to be less than or equal to 0.8, the pressure relief groove is closer to the electrode terminal in the first direction, so as to enhance the reinforcing effect of the electrode terminal on the structural rigidity of the area where the pressure relief groove is provided on the first wall, which is beneficial to reduce the strain and strain amplitude of the area where the pressure relief groove is provided on the first wall, thereby reducing the phenomenon of low-cycle fatigue in the area where the pressure relief groove is provided on the first wall, so as to reduce the premature valve opening of the battery cell. The risk of thermal runaway gas inside the battery cell on the electrode terminal and other components connected to the electrode terminal can be reduced, thereby effectively improving the service life and reliability of the battery cell. On the other hand, by setting the ratio of the minimum distance between the pressure relief groove and the electrode terminal in the first direction to the minimum distance between the pressure relief groove and the first edge in the first direction to be greater than or equal to 0.2, the phenomenon of the pressure relief groove being too close to the electrode terminal can be alleviated, so that when the first wall is cracked along at least part of the pressure relief groove and the internal pressure of the battery cell is released, the impact of the thermal runaway gas inside the battery cell on the electrode terminal and other components connected to the electrode terminal can be reduced, thereby reducing the risk of short circuit or heat diffusion caused by damage to the electrode terminal and other components connected to the electrode terminal, thereby improving the reliability of the battery cell.

[0013] In some embodiments, along the first direction, the minimum distance between the pressure relief groove and the electrode terminal is L 1 , the minimum distance between the pressure relief groove and the first edge is L 2 , satisfying, 0.2≤L 1 / L 2 ≤0.6.

[0014] In the above technical solution, by further setting the ratio of the minimum distance between the pressure relief groove and the electrode terminal in the first direction to the minimum distance between the pressure relief groove and the first edge in the first direction to be less than or equal to 0.6, the pressure relief groove can be further close to the electrode terminal in the first direction, so as to further enhance the reinforcing effect of the electrode terminal on the structural rigidity of the area where the pressure relief groove is provided on the first wall, which is beneficial to reduce the strain and strain amplitude of the area where the pressure relief groove is provided on the first wall, thereby further reducing the phenomenon of low-cycle fatigue in the area where the pressure relief groove is provided on the first wall, so as to further reduce the risk of premature valve opening of the battery cell, thereby effectively improving the service life and reliability of the battery cell.

[0015] In some embodiments, the pressure relief groove and the electrode terminal are arranged along a first direction, and the first direction is perpendicular to the thickness direction of the first wall; wherein, along the first direction, the minimum distance between the pressure relief groove and the electrode terminal is L 1 , the thickness of the portion of the first wall between the pressure relief groove and the electrode terminal is D, satisfying, 3≤L 1 / D≤30.

[0016] In the above technical scheme, the ratio of the minimum distance between the pressure relief groove and the electrode terminal in the first direction to the thickness of the portion of the first wall located between the pressure relief groove and the electrode terminal is 3 to 30. On the one hand, by setting the ratio of the minimum distance between the pressure relief groove and the electrode terminal in the first direction to the thickness of the portion of the first wall located between the pressure relief groove and the electrode terminal to be less than or equal to 30, the phenomenon that the minimum distance between the pressure relief groove and the electrode terminal in the first direction is too large and the thickness of the portion of the first wall located between the pressure relief groove and the electrode terminal is too small can be alleviated, which is beneficial to enhance the structural rigidity of the electrode terminal and the first wall on the area where the pressure relief groove is provided on the first wall, so as to reduce the strain and strain amplitude in the area where the pressure relief groove is provided on the first wall, thereby reducing the phenomenon of low-cycle fatigue in the area where the pressure relief groove is provided on the first wall, thereby reducing the risk of premature valve opening of the battery cell, and thus effectively improving the battery cell. On the one hand, the service life and reliability of use of the battery cell are improved. On the other hand, by setting the ratio of the minimum distance between the pressure relief groove and the electrode terminal in the first direction and the thickness of the first wall between the pressure relief groove and the electrode terminal to be greater than or equal to 3, the phenomenon that the minimum distance between the pressure relief groove and the electrode terminal in the first direction is too small and the thickness of the first wall between the pressure relief groove and the electrode terminal is too large can be alleviated, thereby alleviating the phenomenon that the thickness of the first wall is excessively wasted, thereby reducing the manufacturing cost of the battery cell, and when the first wall is cracked along at least part of the pressure relief groove and releases the internal pressure of the battery cell, the impact of the thermal runaway gas inside the battery cell on the electrode terminal and other components connected to the electrode terminal can be reduced, thereby reducing the risk of short circuit or heat diffusion caused by damage to the electrode terminal and other components connected to the electrode terminal, thereby improving the reliability of use of the battery cell.

[0017] In some embodiments, along the first direction, the minimum distance between the pressure relief groove and the electrode terminal is L 1 , the thickness of the portion of the first wall between the pressure relief groove and the electrode terminal is D, satisfying, 5≤L 1 / D≤25.

[0018] In the above technical solution, by setting the ratio of the minimum distance between the pressure relief groove and the electrode terminal in the first direction and the thickness of the portion of the first wall located between the pressure relief groove and the electrode terminal to be less than or equal to 25, the phenomenon that the minimum distance between the pressure relief groove and the electrode terminal in the first direction is too large and the thickness of the portion of the first wall located between the pressure relief groove and the electrode terminal is too small can be further alleviated, which is beneficial to further enhance the reinforcing effect of the electrode terminal and the first wall on the structural rigidity of the area where the pressure relief groove is provided on the first wall, so as to further reduce the strain and strain amplitude of the area where the pressure relief groove is provided on the first wall, thereby effectively reducing the phenomenon of low cycle fatigue in the area where the pressure relief groove is provided on the first wall, so as to further reduce the risk of battery cell failure. In order to reduce the risk of premature valve opening, similarly, by setting the ratio of the minimum distance between the pressure relief groove and the electrode terminal in the first direction and the thickness of the first wall between the pressure relief groove and the electrode terminal to be greater than or equal to 5, the phenomenon that the minimum distance between the pressure relief groove and the electrode terminal in the first direction is too small and the thickness of the first wall between the pressure relief groove and the electrode terminal is too large can be further alleviated. On the one hand, the phenomenon of excessive waste of thickness of the first wall can be further alleviated. On the other hand, when the first wall is cracked along at least part of the pressure relief groove and the internal pressure of the battery cell is released, the impact of the thermal runaway gas inside the battery cell on the electrode terminal and other components connected to the electrode terminal can be further reduced.

[0019] In some embodiments, a portion of the first wall between the pressure relief groove and the electrode terminal has a thickness D, satisfying 0.8 mm ≤ D ≤ 4 mm.

[0020] In the above technical solution, by setting the thickness of the portion of the first wall located between the pressure relief groove and the electrode terminal to be greater than or equal to 0.8 mm and less than or equal to 4 mm, on the one hand, the structural strength of the portion of the first wall located between the pressure relief groove and the electrode terminal can be improved to reduce the risk of breakage or damage of the first wall during use; on the other hand, the phenomenon of excessive waste of thickness of the first wall can be reduced, which is conducive to reducing the manufacturing difficulty and manufacturing cost of the first wall.

[0021] In some embodiments, the pressure relief groove and the electrode terminal are arranged along a first direction, and the first direction is perpendicular to the thickness direction of the first wall; wherein, along the first direction, the minimum distance between the pressure relief groove and the electrode terminal is L 1 , meet, 10mm≤L 1 ≤100mm.

[0022] In the above technical solution, the minimum distance between the pressure relief groove and the electrode terminal in the first direction is 10 mm to 100 mm. On the one hand, by setting the minimum distance between the pressure relief groove and the electrode terminal in the first direction to be less than or equal to 100 mm, the pressure relief groove is closer to the electrode terminal, so as to enhance the reinforcing effect of the electrode terminal on the structural rigidity of the area where the pressure relief groove is provided on the first wall, which is beneficial to reduce the strain and strain amplitude of the area where the pressure relief groove is provided on the first wall, thereby reducing the phenomenon of low-cycle fatigue in the area where the pressure relief groove is provided on the first wall, so as to reduce the risk of premature valve opening of the battery cell, thereby effectively improving the service life and use reliability of the battery cell. On the other hand, by setting the minimum distance between the pressure relief groove and the electrode terminal in the first direction to be greater than or equal to 10 mm, the phenomenon of the pressure relief groove being too close to the electrode terminal is alleviated, so as to reduce the impact of the thermal runaway gas inside the battery cell on the electrode terminal and other components connected to the electrode terminal when the first wall is cracked along at least part of the pressure relief groove and releases the internal pressure of the battery cell, thereby reducing the risk of short circuit or heat diffusion caused by damage to the electrode terminal and other components connected to the electrode terminal, thereby improving the use reliability of the battery cell.

[0023] In some embodiments, along the first direction, the minimum distance between the pressure relief groove and the electrode terminal is L 1 , meet, 15mm≤L 1 ≤50mm.

[0024] In the above technical solution, the minimum distance between the pressure relief groove and the electrode terminal in the first direction is 15mm to 50mm. On the one hand, by further setting the minimum distance between the pressure relief groove and the electrode terminal in the first direction to be less than or equal to 50mm, the pressure relief groove is closer to the electrode terminal, so as to further enhance the structural rigidity of the region where the pressure relief groove is provided on the first wall, which is beneficial to reduce the strain and strain amplitude of the region where the pressure relief groove is provided on the first wall, thereby further reducing the phenomenon of low-cycle fatigue in the region where the pressure relief groove is provided on the first wall, further reducing the risk of premature valve opening of the battery cell, and thus effectively improving the battery The service life and reliability of the battery cell are improved. On the other hand, the minimum distance between the pressure relief groove and the electrode terminal in the first direction is further set to be greater than or equal to 15 mm, so as to further alleviate the phenomenon that the pressure relief groove is too close to the electrode terminal, so that when the first wall is cracked along at least part of the pressure relief groove and the internal pressure of the battery cell is released, the impact of the thermal runaway gas inside the battery cell on the electrode terminal and other components connected to the electrode terminal can be further reduced, thereby further reducing the risk of short circuit or heat diffusion caused by damage to the electrode terminal and other components connected to the electrode terminal, so as to improve the reliability of the battery cell.

[0025] In some embodiments, the battery cell includes two electrode terminals, both of which are disposed on the first wall, and the two electrode terminals are spaced apart along a first direction, and the first direction is perpendicular to the thickness direction of the first wall; wherein, along the first direction, the pressure relief groove is located between the two electrode terminals.

[0026] In the above technical solution, by arranging both electrode terminals of the battery cell on the first wall and arranging the pressure relief groove between the two electrode terminals in the first direction, the two electrode terminals can further enhance the reinforcing effect on the structural rigidity of the area where the pressure relief groove is arranged on the first wall, which is beneficial to reduce the strain and strain amplitude of the area where the pressure relief groove is arranged on the first wall, thereby further reducing the low-cycle fatigue phenomenon in the area where the pressure relief groove is arranged on the first wall, further reducing the risk of premature valve opening of the battery cell, and helping to improve the service life and reliability of the battery cell.

[0027] In some embodiments, along the first direction, the minimum distance between the pressure relief groove and the two electrode terminals is equal.

[0028] In the above technical scheme, by setting the pressure relief groove to have an equal spacing with the two electrode terminals in the first direction, on the one hand, the structural regularity of the battery cell can be improved, which is beneficial to reducing the manufacturing difficulty of the battery cell; on the other hand, the two electrode terminals can achieve similar reinforcing effects on the structural rigidity of the area where the pressure relief groove is provided on the first wall, which is beneficial to further reduce the strain and strain amplitude of the area where the pressure relief groove is provided on the first wall, so as to alleviate the phenomenon of low-cycle fatigue in the area where the pressure relief groove is provided on the first wall, thereby further reducing the risk of premature valve opening in the battery cell.

[0029] In some embodiments, the first wall is provided with a mounting hole, the mounting hole passes through the first wall along the thickness direction of the first wall, and the mounting hole corresponds to the electrode terminal one by one; wherein the electrode terminal comprises a column portion, a first limiting portion and a second limiting portion, the column portion passes through the mounting hole along the thickness direction of the first wall, and the column portion connects the first limiting portion and the second limiting portion, the first limiting portion and the second limiting portion both protrude from the outer circumferential surface of the column portion, and along the thickness direction of the first wall, the first limiting portion and the second limiting portion are respectively located on both sides of the first wall, and at least part of the projection of the first limiting portion and the projection of the second limiting portion overlap with the first wall.

[0030] In the above technical solution, the electrode terminal is provided with a first limiting portion, a second limiting portion and a column portion connecting the first limiting portion and the second limiting portion, the column portion is passed through the mounting hole of the first wall, and the first limiting portion and the second limiting portion are respectively located on both sides of the first wall and overlap with at least part of the first wall, so as to realize fastening and mounting the electrode terminal on the first wall. The electrode terminal adopting such a structure can, on the one hand, improve the structural stability and reliability of the electrode terminal arranged on the first wall, and on the other hand, can further improve the effect of reinforcing the structural rigidity of the area where the pressure relief groove is arranged on the first wall by the electrode terminal.

[0031] In some embodiments, the projection of the first wall in the thickness direction of the first wall is rectangular, the size of the first wall in the first direction is larger than the size of the first wall in the second direction, and the thickness direction of the first wall, the first direction and the second direction are perpendicular to each other; wherein the pressure relief groove and the electrode terminal are arranged along the first direction.

[0032] In the above technical solution, the first wall is a rectangular structure. By setting the arrangement direction of the pressure relief grooves and the electrode terminals to be consistent with the length direction of the first wall, on the one hand, the difficulty of installing the electrode terminals and setting the pressure relief grooves on the first wall can be reduced, so that the first wall has sufficient space in the first direction to set the electrode terminals and the pressure relief grooves. On the other hand, the electrode terminals can strengthen the structural rigidity of the first wall in the direction in which the first wall is most likely to deform, which is beneficial to further improve the deformation resistance of the first wall, so as to reduce the strain and strain amplitude of the area of ​​the first wall where the pressure relief grooves are set, thereby further reducing the phenomenon of low-cycle fatigue in the area of ​​the first wall where the pressure relief grooves are set, so as to further reduce the risk of premature valve opening of the battery cell.

[0033] In some embodiments, the outer shell is in the shape of a rectangular parallelepiped, and the outer shell also has two second walls, which are arranged opposite to each other along the second direction and are respectively connected to the two ends of the first wall; wherein, along the second direction, the surface of the second wall facing away from the electrode assembly is the surface with the largest area among the outer surfaces of the outer shell.

[0034] In the above technical solution, the outer shell is in the shape of a rectangular parallelepiped, and the outer shell also has two second walls arranged relatively in the second direction, and the surface of the second wall facing away from the electrode assembly is the surface with the largest area in the outer surface of the outer shell, so that the second direction is both the width direction of the first wall and the thickness direction of the battery cell, so that the electrode terminal can strengthen the structural rigidity of the first wall in the direction where the deformation of the first wall is the largest, which is beneficial to further improve the deformation resistance of the first wall, so as to reduce the strain and strain amplitude of the area where the pressure relief groove is provided on the first wall, so as to further reduce the phenomenon of low-cycle fatigue in the area where the pressure relief groove is provided on the first wall, so as to further reduce the risk of premature valve opening of the battery cell.

[0035] In some embodiments, the pressure relief groove is stamped and formed on the first wall.

[0036] In the above technical solution, by setting the pressure relief groove as a structure stamped on the first wall, the molding method of the pressure relief groove on the first wall is simple, which is beneficial to reducing the manufacturing cost of the battery cell.

[0037] In some embodiments, the pressure relief groove includes a plurality of grooves arranged in sequence along the thickness direction of the first wall.

[0038] In the above technical scheme, the pressure relief groove is set as a multi-step stepped groove structure arranged along the thickness direction of the first wall, so that the pressure relief groove is a groove structure formed by multiple processing. Under the condition of the same depth, the pressure relief groove adopting this structure can reduce the depth of the single processing of the pressure relief groove, which is beneficial to reduce the manufacturing difficulty of the pressure relief groove and the demand for manufacturing equipment, so as to reduce the manufacturing cost, and can reduce the forming force applied to the first wall during the single processing of the pressure relief groove, which is beneficial to reduce the risk of cracks in the first wall, so as to improve the production quality of the battery cell, and on the other hand, can improve the flow shape of the pressure relief groove during the formation process, which is beneficial to the flow of the material generated when the pressure relief groove is formed, so as to improve the structural consistency of the pressure relief groove.

[0039] In some embodiments, along the thickness direction of the first wall, the minimum residual thickness of the pressure relief groove is D 3 , meet, 0.05mm≤D 3 ≤0.3mm.

[0040] In the above technical solution, the minimum residual thickness of the pressure relief groove in the thickness direction of the first wall is 0.05mm to 0.3mm. On the one hand, by setting the minimum residual thickness of the pressure relief groove in the thickness direction of the first wall to be greater than or equal to 0.05mm, the structural strength of the area of ​​the first wall where the pressure relief groove is provided is too low, thereby reducing the risk of cracking or damage in the area of ​​the first wall where the pressure relief groove is provided during production, transportation or normal use. On the other hand, by setting the minimum residual thickness of the pressure relief groove in the thickness direction of the first wall to be less than or equal to 0.3mm, the difficulty of the first wall cracking along the pressure relief groove when thermal runaway occurs in the battery cell is alleviated, thereby reducing the bursting pressure required for the battery cell to release the pressure and open the valve, thereby reducing the risk of explosion of the battery cell caused by excessive pressure relief bursting pressure.

[0041] In some embodiments, the battery cell further comprises an electrolyte contained in the housing; wherein the electrolyte comprises an electrolyte salt, the electrolyte salt comprises hexafluorophosphate, and the molar concentration of the hexafluorophosphate is less than or equal to 1.1 mol / L.

[0042] In the above technical solution, by setting the molar concentration of hexafluorophosphate in the electrolyte to be less than or equal to 1.1 mol / L, the amount of hydrofluoric acid generated by the battery cell during use can be reduced, thereby reducing the corrosion of the area where the pressure relief groove is provided on the first wall, and alleviating the further reduction in the minimum residual thickness of the pressure relief groove, thereby reducing the risk of premature cracking or damage of the battery cell due to the decrease in structural strength of the area where the pressure relief groove is provided on the first wall, so as to further improve the reliability and stability of the battery cell.

[0043] In some embodiments, a first weak portion is formed at the bottom of the pressure relief groove, and the first wall is configured to be able to split along at least a portion of the first weak portion when the battery cell is depressurized; wherein, the first wall is also provided with a guide groove, and a second weak portion is formed at the bottom of the guide groove, and along the thickness direction of the first wall, the projection of the pressure relief groove and the projection of at least one of the guide grooves jointly define at least one predetermined pressure relief area, and the second weak portion is configured to guide at least a portion of the predetermined pressure relief area to flip over so as to open at least a portion of the predetermined pressure relief area.

[0044] In the above technical solution, a guide groove is further provided on the first wall, and the projections of the guide groove and the pressure relief groove along the thickness direction of the first wall define at least one predetermined pressure relief area on the first wall, and the predetermined pressure relief area can be opened after the first wall is at least partially cracked along the pressure relief groove, and can be flipped around the second weak portion at the bottom of the guide groove to release the internal pressure of the battery cell. The battery cell adopting this structure can expand the flipping angle of the predetermined pressure relief area after the predetermined pressure relief area is opened, thereby effectively increasing the pressure relief area of ​​the battery cell, so as to improve the pressure relief rate of the battery cell when thermal runaway occurs, and further reduce the risk of fire and explosion of the battery cell due to untimely pressure relief, which is beneficial to improving the reliability of the battery cell.

[0045] In some embodiments, the pressure relief groove and the electrode terminal are arranged along a first direction, the pressure relief groove and the guide groove are arranged along a second direction, and the thickness direction of the first wall, the first direction, and the second direction are perpendicular to each other.

[0046] In the above technical solution, by setting the guide groove and the pressure relief groove as a structure arranged along the second direction, the guide groove is located on at least one side of the pressure relief groove in the second direction. On the one hand, the influence of the guide groove on the structural stiffness of the area of ​​the first wall between the electrode terminal and the pressure relief groove can be reduced, which is beneficial to improving the reinforcing effect of the electrode terminal on the structural stiffness of the area of ​​the first wall where the pressure relief groove is provided. On the other hand, the interference between the pressure relief groove and the guide groove can be reduced, so as to facilitate the processing of the pressure relief groove and the guide groove separately, and can alleviate the phenomenon that the first weak part at the bottom of the pressure relief groove tears the second weak part at the bottom of the guide groove when it is cracked, and can also improve the effect of flipping around the second weak part after the predetermined pressure relief area is opened.

[0047] In some embodiments, the guide groove extends along the first direction, and along the first direction, two ends of the guide groove extend out of two end portions of the pressure relief groove respectively.

[0048] In the above technical solution, by setting the guide groove to be a structure extending along the first direction and with both ends in the first direction respectively exceeding the two end portions of the pressure relief groove, on the one hand, the size of the guide groove in the first direction is larger than the pressure relief groove, so that the predetermined pressure relief area defined by the pressure relief groove can be flipped around the second weak portion, and the flipping effect of the predetermined pressure relief area can be improved, thereby increasing the pressure relief area of ​​the battery cell to improve the pressure relief rate of the battery cell when thermal runaway occurs. On the other hand, the absorption effect of the guide groove on the excess material squeezed out of the pressure relief groove of the first wall during the molding process can be improved, and the effect of the guide groove on separating the edge of the pressure relief groove and the first wall in the second direction can be improved, so as to improve the blocking effect of the guide groove on the deformation energy of the battery cell when the battery cell is subjected to internal and external impact forces.

[0049] In some embodiments, along a thickness direction of the first wall, a projection of the guide groove does not overlap with a projection of the electrode terminal.

[0050] In the above technical solution, by setting the projections of the guide groove and the electrode terminal in the thickness direction of the first wall to be non-overlapping structures, the interference between the guide groove and the electrode terminal can be reduced, which is conducive to reducing the difficulty of manufacturing the battery cell.

[0051] In some embodiments, along the thickness direction of the first wall, the thickness of the second weak portion is greater than the thickness of the first weak portion.

[0052] In the above technical solution, by setting the thickness of the second weak portion in the thickness direction of the first wall to be greater than the thickness of the first weak portion in the thickness direction of the first wall, so that the residual thickness of the guide groove is greater than the residual thickness of the pressure relief groove, the structural strength of the area where the pressure relief groove is set on the first wall is smaller than the structural strength of the area where the guide groove is set on the first wall, so that the first wall can preferentially crack along the first weak portion at the bottom of the pressure relief groove and release the internal pressure of the battery cell, which is conducive to alleviating the phenomenon that the first wall cracks from the area where the guide groove is set, causing poor pressure relief effect of the battery cell.

[0053] In some embodiments, the first weak portion includes at least one weak segment, and the cross-sectional area of ​​the weak segment perpendicular to its extension direction is a first cross-sectional area S 1 The cross-sectional area of ​​the second weak portion perpendicular to its extension direction is the second cross-sectional area S 2 , meet, S 1 <S 2 .

[0054] In the above technical solution, by setting the area of ​​the cross section of the weak section of the first weak portion perpendicular to its extension direction to be smaller than the area of ​​the cross section of the second weak portion perpendicular to its extension direction, the structural strength of the area where the pressure relief groove is set on the first wall is smaller than the structural strength of the area where the guide groove is set on the first wall, so that the first wall can preferentially crack along the first weak portion at the bottom of the pressure relief groove and release the internal pressure of the battery cell, which is conducive to alleviating the phenomenon that the first wall cracks from the area where the guide groove is set, causing poor pressure relief effect of the battery cell.

[0055] In some embodiments, along the thickness direction of the first wall, the pressure relief groove and the guide groove are respectively arranged on both sides of the first wall.

[0056] In the above technical solution, by respectively arranging the pressure relief groove and the guide groove on both sides of the first wall in the thickness direction of the first wall, it is convenient to process the pressure relief groove and the guide groove on both sides of the first wall respectively, which is beneficial to reduce the mutual influence of the pressure relief groove and the guide groove during the processing.

[0057] In some embodiments, the pressure relief groove includes a first groove section and two second groove sections, the two second groove sections are arranged opposite to each other along the first direction, and the second groove section and the guide groove are arranged along the second direction, the first groove section connects the two second groove sections, and the thickness direction of the first wall, the first direction and the second direction are perpendicular to each other; along the thickness direction of the first wall, the projection of the first groove section, the projection of the two second groove sections, the projection of the extension lines of the two second groove sections and the projection of the guide groove together enclose the predetermined pressure relief area; or, along the thickness direction of the first wall, the projection of the first groove section, the projection of the two second groove sections, the projection of the guide groove and the projection of the extension line of the guide groove together enclose the predetermined pressure relief area; or, along the thickness direction of the first wall, the projection of the first groove section, the projection of the two second groove sections, the projection of the extension lines of the two second groove sections, the projection of the guide groove and the projection of the extension line of the guide groove together enclose the predetermined pressure relief area.

[0058] In the above technical solution, the battery cell adopting this structure, on the one hand, is convenient for processing the pressure relief groove on the first wall and forming a predetermined pressure relief area, and the predetermined pressure relief area defined by the pressure relief groove of this structure is easier to flip around the position where the guide groove is located. On the other hand, it makes the intersection of the first groove section and the second groove section weaker, and it is easier to crack and open the predetermined pressure relief area for pressure relief.

[0059] In some embodiments, the pressure relief groove includes a first groove section and a second groove section, and the first groove section and the second groove section are connected; wherein, along the thickness direction of the first wall, the projection of the first groove section, the projection of the extension line of the first groove section, the projection of the second groove section, the projection of the extension line of the second groove section and the projection of the guide groove together enclose the predetermined pressure relief area; or, along the thickness direction of the first wall, the projection of the first groove section, the projection of the second groove section, the projection of the guide groove and the projection of the extension line of the guide groove together enclose the predetermined pressure relief area; or, along the thickness direction of the first wall, the projection of the first groove section, the projection of the extension line of the first groove section, the projection of the second groove section, the projection of the extension line of the second groove section, the projection of the guide groove and the projection of the extension line of the guide groove together enclose the predetermined pressure relief area.

[0060] In the above technical solution, by setting the pressure relief groove to include a first groove section and a second groove section connected to each other, the battery cell adopting this structure can, on the one hand, increase the pressure relief area of ​​the battery cell to improve the pressure relief rate of the battery cell, and on the other hand, make the intersection of the first groove section and the second groove section weaker, easier to crack and open the predetermined pressure relief area to release the internal pressure of the battery cell.

[0061] In some embodiments, the pressure relief groove is a groove extending along an arc trajectory; wherein, along the thickness direction of the first wall, the projection of the pressure relief groove, the projection of the extension line of the pressure relief groove and the projection of the guide groove together enclose the predetermined pressure relief area; or, along the thickness direction of the first wall, the projection of the pressure relief groove, the projection of the guide groove and the projection of the extension line of the guide groove together enclose the predetermined pressure relief area; or, along the thickness direction of the first wall, the projection of the pressure relief groove, the projection of the extension line of the pressure relief groove, the projection of the guide groove and the projection of the extension line of the guide groove together enclose the predetermined pressure relief area.

[0062] In the above technical solution, the pressure relief groove is set as a structure extending along an arc trajectory so that a predetermined pressure relief area is formed on the inner side of the pressure relief groove. The pressure relief groove with this structure is easy to manufacture on the first wall, which is beneficial to reduce the manufacturing difficulty of the battery cell.

[0063] In some embodiments, the guide groove is stamped on the first wall.

[0064] In the above technical solution, by setting the guide groove as a structure stamped on the first wall, the forming method of the guide groove on the first wall is simple, which is beneficial to reducing the manufacturing cost of the battery cell.

[0065] In some embodiments, along a thickness direction of the first wall, the first wall is configured to support the electrode assembly.

[0066] In the above technical solution, the first wall can support the electrode assembly in the thickness direction of the first wall, so that the battery cell is a structure that can be placed inverted. On the one hand, it enables the battery cell to adapt to more usage scenarios to improve the adaptability of the battery cell. On the other hand, it can achieve that the pressure relief groove and electrode terminal of the battery cell are both located at the bottom of the battery cell to facilitate assembly and the release of the internal pressure of the battery cell.

[0067] In some embodiments, the outer shell includes a shell and an end cover; the interior of the shell forms a accommodating cavity with an opening, and the accommodating cavity is used to accommodate the electrode assembly; the end cover closes the opening; wherein the shell includes the first wall; or, the end cover is the first wall.

[0068] In the above technical solution, by setting the first wall of the shell as a wall of the shell, the battery cell adopting this structure can make the area of ​​the shell with the pressure relief groove far away from the end cover, so as to effectively alleviate the phenomenon that the stress generated by the connection between the end cover and the shell acts on the area of ​​the first wall with the pressure relief groove, so as to reduce the impact on the area of ​​the first wall with the pressure relief groove, thereby helping to reduce the risk of cracking or structural strength reduction in the area of ​​the first wall with the pressure relief groove under the pulling effect of stress, so as to improve the service life and reliability of the battery cell. By setting the first wall of the shell as the end cover of the shell for closing the opening, the battery cell adopting this structure is convenient for setting the pressure relief groove on the end cover and installing the electrode terminal, which is conducive to reducing the manufacturing difficulty of the battery cell and improving the production efficiency of the battery cell.

[0069] In some embodiments, the outer shell includes a shell and two end covers; a accommodating cavity is formed inside the shell, and the accommodating cavity is used to accommodate the electrode assembly, and openings are formed at both opposite ends of the shell, and both openings are connected to the accommodating cavity; the two end covers respectively close the two openings; wherein, one of the two end covers is the first wall; or, the shell includes the first wall.

[0070] In the above technical solution, the shell of the shell is provided with an opening structure at both opposite ends, and two end covers respectively close the two openings, and the first wall is one of the two end covers. The battery cell using this structure is convenient for assembling the battery cell from both ends of the shell, which is conducive to reducing the manufacturing difficulty and assembly difficulty of the battery cell, and is convenient for setting the pressure relief groove and installing the electrode terminal on the end cover, which is conducive to reducing the manufacturing difficulty of the battery cell, so as to improve the production efficiency of the battery cell. By setting the first wall of the shell as a wall of the shell, the battery cell using this structure can make the area of ​​the shell with the pressure relief groove away from the end cover, so as to effectively alleviate the phenomenon that the stress generated by the connection between the end cover and the shell acts on the area of ​​the first wall with the pressure relief groove, so as to reduce the impact on the area of ​​the first wall with the pressure relief groove, and further help to reduce the risk of cracking or structural strength reduction in the area of ​​the first wall with the pressure relief groove under the pulling action of stress, so as to improve the service life and reliability of the battery cell.

[0071] In a second aspect, an embodiment of the present application further provides a battery, comprising the above-mentioned battery cell.

[0072] In some embodiments, the battery further comprises a box body, the battery cell is accommodated in the box body, the box body has a bottom plate located at the bottom of the battery cell, and along the thickness direction of the first wall, the bottom plate and the first wall are arranged facing each other.

[0073] In the above technical solution, by arranging the bottom plate of the box body and the first wall of the battery cell facing each other in the thickness direction of the first wall, the battery cell is made to be an inverted structure arranged in the box body, so that the pressure relief groove and the electrode terminal of the battery cell are both located at the bottom of the battery cell and facing the bottom plate, so as to facilitate assembly and release of the internal pressure of the battery cell, and can alleviate the risk of upward impact of thermal runaway gas released from the battery cell of the battery during thermal runaway to the user.

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

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

[0076] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0077] Figure 2 An exploded view of the structure of a battery provided in some embodiments of the present application;

[0078] Figure 3 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0079] Figure 4 An exploded view of the structure of a battery cell provided in some embodiments of the present application;

[0080] Figure 5 A front view of a battery cell provided in some embodiments of the present application, facing the pressure relief groove in the thickness direction of the first wall;

[0081] Figure 6 for Figure 5 A partial enlarged view of the battery cell at A shown;

[0082] Figure 7 A front view of a battery cell provided in some other embodiments of the present application, facing the pressure relief groove in the thickness direction of the first wall;

[0083] Figure 8 A partial cross-sectional view of a first wall of a housing of a battery cell provided in some embodiments of the present application;

[0084] Fig. 9A front view of a battery cell provided in some further embodiments of the present application, facing the pressure relief groove in the thickness direction of the first wall;

[0085] Fig.10 A front view of a battery cell provided in some other embodiments of the present application, facing the pressure relief groove in the thickness direction of the first wall;

[0086] Fig.11 Still some embodiments of the present application provide a front view of a battery cell facing the pressure relief groove in the thickness direction of the first wall.

[0087] Icon: 1000-vehicle; 100-battery; 10-casing; 11-first casing body; 12-second casing body; 20-battery cell; 21-casing; 211-first wall; 2111-pressure relief groove; 2111a-first groove section; 2111b-second groove section; 2111c-first weak portion; 2112-first edge; 2113-predetermined pressure relief area; 2114-guide groove; 2114a-second weak portion; 212-casing; 2121-opening; 213-end cover; 214-second wall; 22-electrode terminal; 23-electrode assembly; 231-ear; 200-controller; 300-motor; X-thickness direction of the first wall; Y-first direction; Z-second direction. DETAILED DESCRIPTION

[0088] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0089] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0090] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0091] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0092] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0093] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0094] The term "plurality" used in the present application refers to two or more (including two).

[0095] 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.

[0096] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0097] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0098] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0099] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0100] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0101] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), 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 LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 、LiMn 2 O 4 ), 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 O 2 (Also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O 2 (Also referred to as NCM 523 )、LiNi 0.5 Co 0.25Mn 0.25 O 2 (Also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (Also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (Also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and at least one of its modified compounds.

[0102] In some embodiments, the positive electrode may be a foamed metal. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, etc. When the foamed metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foamed metal, but of course, the positive electrode active material may also be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled or / and deposited in the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0103] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0104] As an example, the negative electrode current collector may be a metal foil, a foamed metal or a composite current collector. For example, as the metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, nickel or titanium, etc. may be used. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, etc. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0105] 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.

[0106] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0107] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0108] 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.

[0109] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0110] In some embodiments, the separator is a separator membrane. There are many types of separator membranes, and any known porous separator membrane with good chemical stability and mechanical stability can be selected.

[0111] As an example, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or may be attached to the surface of the positive and negative electrodes.

[0112] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0113] In some embodiments, the battery cell further includes an electrolyte, which plays a role in conducting ions between the positive and negative electrodes. The electrolyte can be liquid, gel or solid. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[0114] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0115] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent may also be an ether solvent. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0116] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0117] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0118] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, and the like.

[0119] 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.

[0120] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0121] 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.

[0122] In some embodiments, the electrode assembly is a laminate structure.

[0123] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets may be alternately stacked.

[0124] 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.

[0125] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded sections that are stacked.

[0126] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0127] As an example, the separator may be disposed continuously, and may be disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0128] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0129] In some embodiments, the electrode assembly is provided with tabs, which can lead current out of the electrode assembly. The tabs include a positive tab and a negative tab.

[0130] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0131] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes but is not limited to a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc.

[0132] 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.

[0133] 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.

[0134] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are accommodated in the case.

[0135] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0136] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0137] Batteries have outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide adaptability, and low self-discharge coefficient. They are an important part of the development of new energy today. The development of battery technology must consider many design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, the safety of the battery also needs to be considered.

[0138] For general battery cells, in order to ensure the safety of the battery cells, a pressure relief structure is usually provided on the outer shell of the battery cell, so as to release the internal pressure of the battery cell through the pressure relief structure, thereby effectively improving the safety of the battery cell. In the related art, the pressure relief structure can be formed on the outer shell by an integrated molding process, that is, the pressure relief structure is an area with a weak structure formed on the outer shell, and the pressure relief structure and the outer shell can also be separate structures. For example, the pressure relief structure can be a pressure relief component connected to the outer shell by welding, clamping or bonding, etc., so that when the internal pressure or temperature of the battery cell reaches a threshold, the pressure relief structure can be actuated and opened to release the internal pressure of the battery cell. However, during the charge and discharge cycle of the battery cell, expansion and contraction will occur, and the deformation caused by the expansion and contraction of the battery cell will be transmitted to the wall of the outer shell provided with the pressure relief structure, causing the wall of the outer shell provided with the pressure relief structure to deform, thereby causing the pressure relief structure provided on the first wall to produce a large strain and strain amplitude, so that the pressure relief structure provided on the first wall will experience low-cycle fatigue, which in turn leads to poor stability in use of the pressure relief structure provided on the first wall, which can easily cause the battery cell to activate pressure relief prematurely during use, which is not conducive to improving the service life and reliability of use of the battery cell.

[0139] Based on the above considerations, in order to solve the problems of short service life and low reliability of battery cells, an embodiment of the present application provides a battery cell, which includes a housing, an electrode terminal and an electrode assembly. The housing has a first wall. The electrode terminal is arranged on the first wall. The electrode assembly is accommodated in the housing, and the electrode assembly is electrically connected to the electrode terminal. The first wall is provided with a pressure relief groove, and the first wall is configured to be able to split along at least part of the pressure relief groove when the battery cell is depressurized, and along the thickness direction of the first wall, the projection of the pressure relief groove does not overlap with the projection of the electrode terminal, and the thickness of the electrode terminal is greater than the thickness of the first wall.

[0140] In a battery cell of this structure, a pressure relief groove is provided on the first wall, so that the first wall can be split along at least part of the pressure relief groove when the battery cell releases pressure, so as to release the internal pressure of the battery cell, wherein, by also assembling the electrode terminal on the first wall, the thickness of the electrode terminal in the thickness direction of the first wall is greater than the thickness of the first wall, and the projection of the electrode terminal in the thickness direction of the first wall does not overlap with the projection of the pressure relief groove in the thickness direction of the first wall, so that the battery cell of this structure can set the electrode terminal and the pressure relief structure of the battery cell on the same wall of the outer shell, so that the structural rigidity of the first wall can be improved by the electrode terminal to improve the deformation resistance of the first wall, so that the deformation phenomenon of the first wall can be alleviated during the use of the battery cell, so as to reduce the strain and strain amplitude of the area of ​​the first wall where the pressure relief groove is provided, and further reduce the phenomenon of low-cycle fatigue in the area of ​​the first wall where the pressure relief groove is provided, so as to reduce the phenomenon of fatigue damage in the area of ​​the first wall where the pressure relief groove is provided, which is beneficial to reduce the risk of premature valve opening of the battery cell, so as to improve the service life and reliability of the battery cell.

[0141] The battery cell disclosed in the embodiment of the present application can be used in, but not limited to, electrical devices such as vehicles, ships or aircraft. A power supply system comprising the battery cell and battery disclosed in the present application can be used to form the electrical device, which is helpful to alleviate the problem of premature valve opening of the battery cell during use, thereby improving the service life and reliability of the battery cell.

[0142] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0143] 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.

[0144] Please refer to Figure 1 , Figure 1A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom of the vehicle 1000, or at the head of the vehicle 1000, or at the tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source or a power source for the vehicle 1000, etc. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for the starting, navigation and working power requirements of the vehicle 1000 during driving.

[0145] In some embodiments of the present application, the battery 100 can not only serve as an operating power source or a use power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0146] Please refer to Figure 2 and Figure 3 , Figure 2 The structure explosion diagram of the battery 100 provided in some embodiments of the present application is shown in FIG. Figure 3 The schematic diagram of the structure of the battery cell 20 provided in some embodiments of the present application is as follows. The battery 100 comprises a box body 10 and a battery cell 20 , and the battery cell 20 is used to be accommodated in the box body 10 .

[0147] The box body 10 is used to provide an assembly space for the battery cell 20, and the box body 10 can adopt a variety of structures. In some embodiments, the box body 10 may include a first box body 11 and a second box body 12, the first box body 11 and the second box body 12 cover each other, and the first box body 11 and the second box body 12 jointly define an assembly space for accommodating the battery cell 20. The second box body 12 may be a hollow structure with one end open, and the first box body 11 may be a plate-like structure, and the first box body 11 covers the open side of the second box body 12, so that the first box body 11 and the second box body 12 jointly define an assembly space; the first box body 11 and the second box body 12 may also be hollow structures with one side open, and the open side of the first box body 11 covers the open side of the second box body 12.

[0148] Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder, a cuboid or a cube. Figure 2 In the embodiment, the box body 10 is in the shape of a rectangular parallelepiped.

[0149] In the battery 100, the battery cell 20 disposed in the box 10 may be one or more. When there are more than one battery cell 20 disposed in the box 10, the multiple battery cells 20 may be connected in series, in parallel, or in mixed connection. Mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells 20 may be accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in mixed connection, and then the multiple battery modules may be connected in series, in parallel, or in mixed connection to form a whole, and then the whole may be accommodated in the box 10.

[0150] In some embodiments, the battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, which is used to connect the plurality of battery cells 20 to achieve electrical connection between the plurality of battery cells 20 .

[0151] Each battery cell 20 may be a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be in a rectangular parallelepiped, a cylinder, a prism or other shapes. For example, Figure 3 In the figure, the battery cell 20 is a rectangular parallelepiped structure.

[0152] According to some embodiments of the present application, referring to Figure 3 , and please refer to Figure 4 , Figure 5 and Figure 6 , Figure 4 This is an exploded view of the structure of the battery cell 20 provided in some embodiments of the present application. Figure 5 A front view of a battery cell 20 provided in some embodiments of the present application facing the pressure relief groove 2111 in the thickness direction X of the first wall, Figure 6 for Figure 5 A partial enlarged view of the battery cell 20 at A shown. The present application provides a battery cell 20, which includes a shell 21, an electrode terminal 22 and an electrode assembly 23. The shell 21 has a first wall 211. The electrode terminal 22 is arranged on the first wall 211. The electrode assembly 23 is accommodated in the shell 21, and the electrode assembly 23 is electrically connected to the electrode terminal 22. The first wall 211 is provided with a pressure relief groove 2111, and the first wall 211 is configured to be able to crack along at least part of the pressure relief groove 2111 when the battery cell 20 is depressurized to release the internal pressure of the battery cell 20. Along the thickness direction X of the first wall, the projection of the pressure relief groove 2111 does not overlap with the projection of the electrode terminal 22, and the thickness of the electrode terminal 22 is greater than the thickness of the first wall 211.

[0153] The housing 21 can also be used to contain electrolytes, such as electrolytes. The housing 21 can be in various structural forms, such as a cylinder, a cuboid, or a prism structure. Similarly, the housing 21 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy.

[0154] In some embodiments, the housing 21 may include a shell 212 and an end cap 213, wherein a receiving cavity is formed inside the shell 212, the receiving cavity is used to receive the electrode assembly 23, and the receiving cavity has an opening 2121, that is, the shell 212 is a hollow structure with an opening 2121 at one end, and the end cap 213 covers the opening 2121 of the shell 212 and forms a sealed connection to form an enclosed space for receiving the electrode assembly 23 and the electrolyte.

[0155] Optionally, the shell 212 includes an integrally formed bottom wall and side wall, the side wall is arranged around the bottom wall, one end of the side wall is connected to the bottom wall, and the other end is enclosed to form an opening 2121, the end cover 213 covers the opening 2121 and is arranged opposite to the bottom wall, and the bottom wall and the side wall jointly define a accommodating cavity for accommodating the electrode assembly 23.

[0156] It should be noted that the first wall 211 provided with the pressure relief groove 2111 and the electrode terminal 22 may be the end cover 213 of the housing 21 or a wall of the shell 212 of the housing 21. Figure 3 and Figure 4 In the figure, the first wall 211 is the end cover 213, that is, the pressure relief groove 2111 is arranged on the end cover 213 of the shell 21, and correspondingly, the electrode terminal 22 is arranged on the end cover 213. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the first wall 211 can also be the bottom wall of the shell 212 arranged opposite to the end cover 213 in the thickness direction X of the first wall, and the first wall 211 can also be the side wall of the shell 212 and the end cover 213 adjacent to and connected to each other.

[0157] Among them, the first wall 211 is provided with a mounting hole, and the mounting hole passes through the surface of both sides of the first wall 211 along the thickness direction X of the first wall. The mounting hole corresponds to the electrode terminal 22 one by one, and at least part of the electrode terminal 22 is inserted into the mounting hole or covers the mounting hole along the thickness direction X of the first wall, so that the electrode terminal 22 can be electrically connected to the electrode assembly 23 accommodated in the outer shell 21.

[0158] The first wall 211 is provided with a pressure relief groove 2111, that is, the pressure relief groove 2111 for pressure relief is formed on the first wall 211 through an integrated molding process, that is, the pressure relief groove 2111 is a structure formed by processing on the first wall 211, and the bottom wall of the pressure relief groove 2111 is a part of the first wall 211. For example, the pressure relief groove 2111 on the first wall 211 can be made by an integrated molding process such as stamping or etching.

[0159] The first wall 211 is configured to be able to split along at least part of the pressure relief groove 2111 when the battery cell 20 releases pressure to release the internal pressure of the battery cell 20. That is, the area of ​​the first wall 211 where the pressure relief groove 2111 is provided forms a weak structure of the first wall 211, and the weak structure is a pressure relief structure of the outer shell 21 of the battery cell 20 for releasing the internal pressure of the battery cell 20, so that when the internal pressure or temperature of the battery cell 20 reaches a predetermined value, the first wall 211 can be split along at least part of the bottom wall of the pressure relief groove 2111 to release the internal pressure of the battery cell 20.

[0160] Optionally, the pressure relief groove 2111 may be disposed on the surface of the first wall 211 facing the electrode assembly 23, or may be disposed on the surface of the first wall 211 facing away from the electrode assembly 23. Similarly, the pressure relief groove 2111 may be in various shapes, for example, the pressure relief groove 2111 may be a strip structure extending along a straight line, a "U"-shaped structure, a "V"-shaped structure, an "S"-shaped structure, an "N"-shaped structure, an "H"-shaped structure, a "Y"-shaped structure, a double "Y"-shaped structure, a rectangular structure, a triangular structure, a circular structure or an elliptical structure, etc. In addition, the pressure relief groove 2111 may be a multi-stage groove disposed along the thickness direction X of the first wall, or may be only a single-stage groove.

[0161] Along the thickness direction X of the first wall, the projection of the pressure relief groove 2111 does not overlap with the projection of the electrode terminal 22, that is, in a plane perpendicular to the thickness direction X of the first wall, the orthographic projection of the pressure relief groove 2111 does not overlap with the orthographic projection of the electrode terminal 22, that is, in a direction perpendicular to the thickness direction X of the first wall, the pressure relief groove 2111 and the electrode terminal 22 are arranged at intervals. For example, Figure 5 In the figure, the pressure relief groove 2111 is located on one side of the electrode terminal 22 in the first direction Y, that is, the pressure relief groove 2111 and the electrode terminal 22 are arranged along the first direction Y. It should be noted that two electrode terminals 22 are provided in the battery cell 20, and the two electrode terminals 22 are both arranged on the first wall 211. Then, the two electrode terminals 22 are arranged at intervals along the first direction Y, and the pressure relief groove 2111 is located between the two electrode terminals 22 in the first direction Y.

[0162] The thickness of the electrode terminal 22 is greater than the thickness of the first wall 211 , that is, the overall size of the electrode terminal 22 in the thickness direction X of the first wall is greater than the wall thickness of the first wall 211 .

[0163] 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 closed on the opening 2121 of the housing 212 to complete the assembly of the battery cell 20 .

[0164] The shell 212 can be in various shapes, such as a cylinder, a cuboid, etc. 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, the shell 212 can be a cylindrical structure; if the electrode assembly 23 is a cuboid structure, the shell 212 can be a cuboid structure. Of course, the end cap 213 can also be in various structures, such as a plate-like structure or a hollow structure with one end open. For example, in Figure 3 and Figure 4 In the embodiment, the shell 212 is a rectangular parallelepiped structure, and the end cover 213 is a rectangular plate structure.

[0165] Of course, it is understandable that the outer shell 21 is not limited to the above structure, and the outer shell 21 may also be other structures. For example, the outer shell 21 may include a shell body 212 and two end caps 213. The shell body 212 is a hollow structure with openings 2121 on opposite sides. One end cap 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 is formed with openings 2121 on opposite sides, and the two end caps 213 are respectively covered on the two sides of the shell body 212 to close the corresponding openings 2121. Correspondingly, the first wall 211 is one of the two end caps 213.

[0166] It should be noted that the electrode assembly 23 is the component where electrochemical reactions occur in the battery cell 20, and the structure of the electrode assembly 23 can be various. For example, the electrode assembly 23 can be a wound structure formed by winding the positive electrode sheet, the separator and the negative electrode sheet, or it can be a stacked structure formed by stacking the positive electrode sheet, the separator and the negative electrode sheet.

[0167] Exemplarily, the isolation member 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.

[0168] Among them, the electrode assembly 23 is formed with a pole ear 231 at one end close to the first wall 211 in the thickness direction X of the first wall. The pole ear 231 is used to input or output the positive electrode or negative electrode of the electrode assembly 23, and the pole ear 231 is used to be electrically connected to the electrode terminal 22. It should be noted that the pole ear 231 of the electrode assembly 23 is a component formed by mutually stacking and connecting the regions on the positive electrode sheet that are not coated with the positive electrode active material layer, or a component formed by mutually stacking and connecting the regions on the negative electrode sheet that are not coated with the negative electrode active material layer. If the pole ear 231 is used to output the positive electrode of the electrode assembly 23, the pole ear 231 is a component formed by mutually stacking and connecting the regions on the positive electrode sheet that are not coated with the positive electrode active material layer; if the pole ear 231 is used to output the negative electrode of the electrode assembly 23, the pole ear 231 is a component formed by mutually stacking and connecting the regions on the negative electrode sheet that are not coated with the negative electrode active material layer.

[0169] Exemplarily, the material of the tab 231 may be copper or aluminum.

[0170] Optionally, the number of electrode assemblies 23 contained in the housing 21 may be one or more. Figure 4 In the embodiment, two electrode assemblies 23 are arranged in the housing 21 of the battery cell 20, and the two electrode assemblies 23 are stacked along the second direction Z, that is, the two electrode assemblies 23 are stacked along the thickness direction of the battery cell 20. Of course, in other embodiments, the number of electrode assemblies 23 accommodated in the housing 21 may be one, three, four, five, six, seven or eight. It should be noted that the thickness direction X of the first wall, the first direction Y and the second direction Z are perpendicular to each other, the thickness direction X of the first wall is the height direction of the battery cell 20, the first direction Y is the length direction of the battery cell 20, and the second direction Z is the thickness direction of the battery cell 20.

[0171] In the embodiment of the present application, the electrode terminal 22 serves to input or output the electric energy of the battery cell 20 . The electrode terminal 22 is electrically connected to the tab 231 to input or output the electric energy of the battery cell 20 .

[0172] It should be noted that the electrode terminal 22 is insulated and installed on the first wall 211 of the outer shell 21, that is, no electrical connection is formed between the electrode terminal 22 and the first wall 211 of the outer shell 21, that is, an insulating member is arranged between the electrode terminal 22 and the first wall 211, and the insulating member is used to insulate and isolate the electrode terminal 22 and the first wall 211, so as to realize the insulated installation of the electrode terminal 22 on the first wall 211 of the outer shell 21, and a sealing member is also arranged between the electrode terminal 22 and the hole wall surface of the mounting hole of the first wall 211, and the sealing member is used to seal the gap between the electrode terminal 22 and the hole wall surface of the mounting hole, so as to alleviate the phenomenon of leakage of electrolyte inside the battery cell 20 from the mounting hole.

[0173] Among them, Figure 4 and Figure 5 In the embodiment, the battery cell 20 includes two electrode terminals 22, both of which are arranged on the first wall 211, and the two electrode terminals 22 are arranged at intervals along the first direction Y and are respectively located on both sides of the pressure relief groove 2111, that is, the pressure relief groove 2111 is located between the two electrode terminals 22 in the first direction Y. Correspondingly, each electrode assembly 23 has two pole ears 231, and the polarities of the two pole ears 231 are opposite. The two electrode terminals 22 are respectively electrically connected to the two pole ears 231 of the electrode assembly 23 to realize the input or output of the positive and negative electrodes of the battery cell 20. It should be noted that in other embodiments, the two electrode terminals 22 may also be that only one electrode terminal 22 is arranged on the first wall 211, and the other electrode terminal 22 is arranged on other walls of the housing 21.

[0174] Optionally, the electrode terminal 22 may be made of a variety of materials. For example, the electrode terminal 22 may be made of copper, iron, aluminum, steel, or aluminum alloy.

[0175] In some embodiments, the battery cell 20 may also include two current collecting components, both of which are arranged in the outer shell 21, and each current collecting component is used to connect an electrode terminal 22 and a plurality of electrode assemblies 23 with the same polarity of the pole lug 231 to achieve electrical connection between the electrode terminal 22 and the electrode assembly 23, which is conducive to reducing the difficulty of assembly between the pole lug 231 and the electrode terminal 22.

[0176] Exemplarily, the material of the current collecting component may be various, for example, the material of the current collecting component may be copper, iron, aluminum, steel or aluminum alloy.

[0177] In this embodiment, a pressure relief groove 2111 is provided on the first wall 211, so that the first wall 211 can be split along at least a portion of the pressure relief groove 2111 when the battery cell 20 releases pressure, so as to release the internal pressure of the battery cell 20, wherein, by assembling the electrode terminal 22 on the first wall 211, the thickness of the electrode terminal 22 in the thickness direction X of the first wall is greater than the thickness of the first wall 211, and the projection of the electrode terminal 22 in the thickness direction X of the first wall does not overlap with the projection of the pressure relief groove 2111 in the thickness direction X of the first wall, so that the battery cell 20 with this structure can arrange the electrode terminal 22 and the pressure relief structure of the battery cell 20 at On the same wall of the outer shell 21, the structural rigidity of the first wall 211 can be improved through the electrode terminal 22 to improve the deformation resistance of the first wall 211, so that the deformation of the first wall 211 can be alleviated during the use of the battery cell 20, so as to reduce the strain and strain amplitude of the area where the pressure relief groove 2111 is provided on the first wall 211, and thus can reduce the low-cycle fatigue phenomenon in the area where the pressure relief groove 2111 is provided on the first wall 211, so as to reduce the fatigue damage phenomenon in the area where the pressure relief groove 2111 is provided on the first wall 211, which is beneficial to reduce the risk of premature valve opening of the battery cell 20, so as to improve the service life and reliability of the battery cell 20.

[0178] According to some embodiments of the present application, see Figure 5 As shown, the pressure relief groove 2111 and the electrode terminal 22 are arranged along the first direction Y, and along the second direction Z, the maximum size of the electrode terminal 22 is D 1 , the maximum dimension of the first wall 211 is D 2 , satisfying, 0.4≤D 1 / D 2 ≤0.9, the thickness direction X of the first wall, the first direction Y and the second direction Z are perpendicular to each other.

[0179] Among them, the maximum size D of the electrode terminal 22 1 It is the maximum space occupied by the electrode terminal 22 in the second direction Z.

[0180] For example, in Figure 5 In the embodiment, the projection of the electrode terminal 22 in the thickness direction X of the first wall is a rectangle, and the length direction of the projection of the electrode terminal 22 in the thickness direction X of the first wall is the first direction Y, then the maximum dimension D of the electrode terminal 22 is 1 is the width dimension of the electrode terminal 22 in the second direction Z.

[0181] The maximum dimension of the first wall 211 is D 2 It is the maximum space occupied by the first wall 211 in the second direction Z.

[0182] For example, in Figure 5In the embodiment, the projection of the first wall 211 in the thickness direction X of the first wall is a rectangle, and the length direction of the projection of the first wall 211 in the thickness direction X of the first wall is the first direction Y, then the maximum dimension of the first wall 211 is D 2 is the width dimension of the first wall 211 in the second direction Z.

[0183] It should be noted that, in other embodiments, the electrode terminal 22 may also be in other shapes, for example, Figure 7 , Figure 7 The front view of the battery cell 20 provided in some embodiments of the present application facing the pressure relief groove 2111 in the thickness direction X of the first wall, the projection of the electrode terminal 22 in the thickness direction X of the first wall is circular, and the maximum size D of the electrode terminal 22 is 1 is the maximum diameter of the electrode terminal 22 .

[0184] 0.4≤D 1 / D 2 ≤0.9, refers to the maximum dimension D of the electrode terminal 22 in the second direction Z 1 The maximum dimension D of the first wall 211 in the second direction Z 2 The ratio is between 0.4 and 0.9.

[0185] Exemplarily, the maximum dimension D of the electrode terminal 22 in the second direction Z is 1 The maximum dimension D of the first wall 211 in the second direction Z 2 The ratio can be 0.4, 0.42, 0.45, 0.48, 0.5, 0.52, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85 or 0.9, etc.

[0186] 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 conjunction with Comparative Examples 1-2 and Examples 1-6. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0187] Comparative Example 1

[0188] 1) Preparation of positive electrode

[0189] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1 O 2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are used to prepare positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the solid content of LiNi 0.7 Co 0.1 Mn 0.1 O 2 The mass ratio of 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 into pieces, and divided into strips, and then dried at 85°C under vacuum conditions for 4 hours to make the positive electrode sheet.

[0190] 2) Preparation of negative electrode

[0191] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry is 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC and adhesive styrene butadiene rubber (SBR) in the solid component is 88:7:3:2. The negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C, and then cold pressed, trimmed, cut into pieces, and slit, and then dried at 120°C under vacuum conditions for 12 hours to prepare a negative electrode sheet.

[0192] 3) Preparation of electrolyte

[0193] In an argon atmosphere glove box (H 2 O<0.1ppm, O 2 <0.1ppm), the fully dried electrolyte salt LiPF 6 The electrolyte 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 uniform mixing, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0194] 4) Isolation parts

[0195] A 16 μm polyethylene film was used as a separator.

[0196] 5) Preparation of battery cell 20

[0197] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is located between the positive and negative electrode sheets to isolate the positive and negative electrodes, and the electrode assembly 23 is wound, and the electrode assembly 23 is placed in an aluminum shell 21, and the electrolyte prepared above is injected into the dried shell 21, and the battery cell 20 is prepared by packaging, standing, forming, shaping, and capacity testing. The shell 21 of the battery cell 20 is a rectangular parallelepiped structure, and the electrode terminal 22 is installed on the first wall 211 of the shell 21, and a pressure relief groove 2111 is provided on the surface of the first wall 211 away from the electrode assembly 23. The pressure relief groove 2111 is in an "H" shape, and the pressure relief groove 2111 is located on one side of the electrode terminal 22 in the first direction Y. Among them, the maximum size D of the electrode terminal 22 of the battery cell 20 of the comparative example 1 in the second direction Z 1 is 12 mm, and the maximum dimension D of the first wall 211 in the second direction Z is 2 is 40 mm so that D 1 With D 2 The ratio is 0.3.

[0198] The preparation methods of the battery cells 20 of Comparative Example 2 and Examples 1-6 are the same as those of Comparative Example 1, except that the maximum dimension D of the electrode terminal 22 in the second direction Z is 1 and the maximum dimension D of the first wall 211 in the second direction Z 2 Different, so that D 1 With D 2 The specific situation is shown in Table 1.

[0199] The maximum dimension D of the electrode terminal 22 in the second direction Z is shown in the following comparison examples 1-2 and embodiments 1-6. 1 and the maximum dimension D of the first wall 211 in the second direction Z 2 The battery cell 20 is tested under different conditions to obtain the cycle fatigue number of the battery cell 20. The specific experimental method and steps are as follows:

[0200] (1) Prepare a special test fixture. Specifically, the fixture consists of three 10 mm steel plates (a first steel plate, a second steel plate and a third steel plate arranged in sequence along the second direction Z, and the thickness directions of the first steel plate, the second steel plate and the third steel plate are all in the second direction Z). 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 so that the second steel plate can only move in translation along its thickness direction.

[0201] (2) The battery cell 20 is installed between the first steel plate and the second steel plate (i.e., it is placed between the first steel plate and the second steel plate in the second direction Z). A support structure is placed between the largest outer surface of one side of the battery cell 20 and the first steel plate, and between the largest outer surface of the other side of the battery cell 20 and the second steel plate (i.e., support structures are placed on both sides of the battery cell 20 in the second direction Z). The support structure may be a heat insulation pad or a water cooling plate (consistent with the material / structure between the battery cells 20 in the actual battery 100). The support structure may be compressed to provide expansion space for the battery cell 20 during the charge and discharge cycle aging process; the largest outer surface of one side of the battery cell 20 is bonded to the support structure, the first steel plate is bonded to the corresponding support structure, the second steel plate is bonded to the corresponding support structure, and a pressure sensor is provided between the second steel plate and the third steel plate;

[0202] (3) By adjusting the pre-tightening force of the bolts to adjust the position of the second steel plate, and observing the pressure sensor, the battery cell 20 is subjected to an initial extrusion force of 2000N, and the two electrode terminals 22 of the battery cell 20 are connected to a dedicated battery 100 charging and discharging device;

[0203] (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;

[0204] (5) The test steps are carried out in accordance with Chapter 6.4 "Standard Cycle Life" of "GBT31484-2015 Requirements and Test Methods for 100 Cycle Life of Power Batteries for Electric Vehicles", and the test cycle cutoff condition is changed to "stop the test until the area where the pressure relief groove 2111 of the first wall 211 is provided is damaged."

[0205] Specifically, test according to the following steps:

[0206] a. 1I 1 (A) Current discharge to 2.8V;

[0207] b. Leave it for no less than 30 minutes;

[0208] c. Charge according to method 6.1.1.3 of GBT31484-2015 Requirements and test methods for 100 cycle life of power batteries for electric vehicles;

[0209] d. Leave it aside for no less than 30 minutes;

[0210] e. 1I 1 (A) Current discharge to 2.8V;

[0211] f. Repeat steps b to e until the area where the pressure relief groove 2111 of the first wall 211 is provided is damaged, then stop the test.

[0212] That is, the test process continuously observes the area of ​​the first wall 211 where the pressure relief groove 2111 is set until the area of ​​the first wall 211 where the pressure relief groove 2111 is set is damaged and leaks, and the number of cycles is recorded as the number of cycle fatigue times of the battery cell 20, wherein a greater number of cycle fatigue times of the battery cell 20 indicates a lower probability of premature cracking in the area of ​​the first wall 211 where the pressure relief groove 2111 is set during long-term use, and a longer service life, thereby making it possible to reasonably predict the likelihood of premature cracking in the area of ​​the first wall 211 where the pressure relief groove 2111 is set during use through the number of cycle fatigue times of the battery cell 20.

[0213] The experimental results of Comparative Examples 1-2 and Examples 1-6 are shown in Table 1 below.

[0214] Table 1

[0215]

[0216] As shown in Table 1, based on the experimental results of Comparative Examples 1-2 and Examples 1-6, it can be seen that the maximum dimension D of the electrode terminal 22 in the second direction Z is 1 and the maximum dimension D of the first wall 211 in the second direction Z 2 When the ratio is less than 0.4, the cycle fatigue number of the battery cell 20 is less than 1000 times, so that the area where the pressure relief groove 2111 is set on the first wall 211 of the shell 21 is very likely to crack prematurely during use, thereby causing the battery cell 20 to have a short service life during use, and the maximum dimension D of the electrode terminal 22 in the second direction Z is less than 0.4. 1 and the maximum dimension D of the first wall 211 in the second direction Z 2 When the ratio is greater than or equal to 0.4, the number of cycle fatigue times of the battery cell 20 can reach more than 1200 times, thereby reducing the phenomenon of premature cracking in the area where the pressure relief groove 2111 is set on the first wall 211 of the shell 21 during use, which is beneficial to improving the service life of the battery cell 20. Therefore, the maximum dimension D of the electrode terminal 22 in the second direction Z is set to 1 and the maximum dimension D of the first wall 211 in the second direction Z 2 The ratio is set to be greater than or equal to 0.4.

[0217] Similarly, the maximum dimension D of the electrode terminal 22 in the second direction Z is 1 and the maximum dimension D of the first wall 211 in the second direction Z 2When the ratio is greater than 0.9, although the number of cycle fatigue of the battery cell 20 is higher, it will cause the electrode terminal 22 to be close to the outer edge of the first wall 211 in the second direction Z, and the mounting hole of the first wall 211 for mounting the electrode terminal 22 will be too large. The hole wall of the mounting hole is close to the outer edge of the first wall 211, resulting in a low structural strength of the area where the electrode terminal 22 is assembled on the first wall 211, which is very easy to be damaged during transportation, production and use. Therefore, the maximum size D of the electrode terminal 22 in the second direction Z is set to 1 and the maximum dimension D of the first wall 211 in the second direction Z 2 The ratio is set to be less than or equal to 0.9.

[0218] In the present embodiment, the ratio of the maximum dimension of the electrode terminal 22 in the second direction Z to the maximum dimension of the first wall 211 in the second direction Z is 0.4 to 0.9. On the one hand, by setting the ratio of the maximum dimension of the electrode terminal 22 in the second direction Z to the maximum dimension of the first wall 211 in the second direction Z to be greater than or equal to 0.4, the space occupied by the electrode terminal 22 in the second direction Z of the first wall 211 can be increased, which is beneficial to enhancing the reinforcing effect of the electrode terminal 22 on the structural rigidity of the first wall 211, so as to enhance the anti-deformation ability of the first wall 211, so as to alleviate the deformation phenomenon of the first wall 211 during the use of the battery cell 20, so as to reduce the strain and strain amplitude of the area where the pressure relief groove 2111 is provided on the first wall 211, thereby reducing the area where the pressure relief groove 2111 is provided on the first wall 211. On the other hand, by setting the ratio of the maximum dimension of the electrode terminal 22 in the second direction Z to the maximum dimension of the first wall 211 in the second direction Z to be less than or equal to 0.9, the phenomenon that the electrode terminal 22 occupies too much space on the first wall 211 in the second direction Z can be alleviated, so as to reduce the phenomenon that the opening of the mounting hole for installing the electrode terminal 22 is too large, thereby reducing the difficulty of assembling the electrode terminal 22 and the difficulty of manufacturing the mounting hole, so as to reduce the difficulty of manufacturing the battery cell 20, and the phenomenon that the structural strength of the area where the mounting hole is set on the first wall 211 is too low, so as to reduce the risk of breakage or damage of the first wall 211 during processing, production or use.

[0219] According to some embodiments of this application, please continue to refer to Figure 5 As shown, along the second direction Z, the maximum dimension of the electrode terminal 22 is D 1 , the maximum dimension of the first wall 211 is D 2 , satisfying, 0.6≤D 1 / D 2 ≤0.9.

[0220] Please continue to refer to Table 1, and based on the experimental results of Comparative Examples 1-2 and Examples 1-6, it can be seen that the maximum dimension D of the electrode terminal 22 in the second direction Z is 1 and the maximum dimension D of the first wall 211 in the second direction Z 2 When the ratio is greater than or equal to 0.6, the cycle fatigue times of the battery cell 20 can reach more than 1500 times, thereby further reducing the phenomenon of premature cracking in the area where the pressure relief groove 2111 is set on the first wall 211 of the shell 21 during use, which is beneficial to improving the service life of the battery cell 20. Therefore, the maximum dimension D of the electrode terminal 22 in the second direction Z is set to 1 and the maximum dimension D of the first wall 211 in the second direction Z 2 The ratio of is further set to be greater than or equal to 0.6.

[0221] In this embodiment, by further setting the ratio of the maximum dimension of the electrode terminal 22 in the second direction Z to the maximum dimension of the first wall 211 in the second direction Z to be greater than or equal to 0.6, the space occupied by the electrode terminal 22 in the first wall 211 in the second direction Z can be further increased, which is beneficial to further enhance the reinforcing effect of the electrode terminal 22 on the structural rigidity of the first wall 211, so as to enhance the deformation resistance of the first wall 211, so as to further alleviate the deformation of the first wall 211 during the use of the battery cell 20, so as to reduce the strain and strain amplitude of the area of ​​the first wall 211 where the pressure relief groove 2111 is provided, and further reduce the phenomenon of low-cycle fatigue in the area of ​​the first wall 211 where the pressure relief groove 2111 is provided, which is beneficial to further reduce the risk of premature valve opening of the battery cell 20, so as to enhance the service life and reliability of the battery cell 20.

[0222] According to some embodiments of the present application, see Figure 5 as well as Figure 7 As shown, the outer edge of the first wall 211 includes a first edge 2112, and the first edge 2112 and the pressure relief groove 2111 are respectively located on both sides of the electrode terminal 22 in the first direction Y, and the first direction Y is perpendicular to the thickness direction X of the first wall. Along the first direction Y, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 is L 1 , the minimum distance between the pressure relief groove 2111 and the first edge 2112 is L 2 , satisfying, 0.2≤L 1 / L 2 ≤0.8.

[0223] Among them, the outer edge of the first wall 211 includes a first edge 2112, and the first edge 2112 and the pressure relief groove 2111 are respectively located on both sides of the electrode terminal 22 in the first direction Y, that is, the first edge 2112 is the edge of one side of the first wall 211 in the first direction Y, and the pressure relief groove 2111, the electrode terminal 22 and the first edge 2112 are arranged in sequence along the first direction Y.

[0224] For example, in Figure 5 In the embodiment, the projection of the first wall 211 in the thickness direction X of the first wall is a rectangle, and the length direction of the projection of the first wall 211 in the thickness direction X of the first wall is the first direction Y, then the first wall 211 has first edges 2112 formed at both ends in the first direction Y. In this embodiment, L 2 The distance in the first direction Y between the pressure relief groove 2111 and the first edge 2112 in the region where the electrode terminal 22 is disposed is taken.

[0225] exist Figure 5 In the embodiment, two electrode terminals 22 are arranged on the first wall 211, the pressure relief groove 2111 is arranged between the two electrode terminals 22 in the first direction Y, and the first edges 2112 are formed at both ends of the first wall 211 in the first direction Y, then L 1 The distance between the pressure relief groove 2111 and one of the electrode terminals 22 in the first direction Y is L 2 The distance between the pressure relief groove 2111 and the first edge 2112 where the corresponding electrode terminal 22 is disposed in the first direction Y is L. 1 and L 2 The values ​​are all based on the same electrode terminal 22.

[0226] It should be noted that, if the first wall 211 is the end cover 213 of the outer shell 21, the first edge 2112 is the edge of the projection of the first wall 211 in the thickness direction X of the first wall in the first direction Y; if the first wall 211 is the bottom wall of the shell 212, the first edge 2112 is the outer surface of the wall of the shell 212 connected to one end of the first wall 211 in the first direction Y, which is away from the electrode assembly 23, that is, the rounded area or chamfered area formed at the edge of the first wall 211 belongs to the first wall 211.

[0227] The minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 1 is the distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y.

[0228] The minimum distance L between the pressure relief groove 2111 and the first edge 2112 2 is the distance between the pressure relief groove 2111 and the first edge 2112 in the first direction Y.

[0229] 0.2≤L 1 / L 2 ≤0.8, which means that the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the minimum distance between the pressure relief groove 2111 and the first edge 2112 in the first direction Y is 0.2 to 0.8.

[0230] Exemplarily, the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the minimum distance between the pressure relief groove 2111 and the first edge 2112 in the first direction Y can be 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75 or 0.8, etc.

[0231] 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 conjunction with Comparative Examples 3-5 and Examples 7-11. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0232] Comparative Example 3

[0233] 1) Preparation of positive electrode

[0234] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1 O 2 , conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are used to prepare positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the solid content of LiNi 0.7 Co 0.1 Mn 0.1 O 2 The mass ratio of 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 into pieces, and divided into strips, and then dried at 85°C under vacuum conditions for 4 hours to make the positive electrode sheet.

[0235] 2) Preparation of negative electrode

[0236] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry is 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC and adhesive styrene butadiene rubber (SBR) in the solid component is 88:7:3:2. The negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C, and then cold pressed, trimmed, cut into pieces, and slit, and then dried at 120°C under vacuum conditions for 12 hours to prepare a negative electrode sheet.

[0237] 3) Preparation of electrolyte

[0238] In an argon atmosphere glove box (H 2 O<0.1ppm, O 2 <0.1ppm), the fully dried electrolyte salt LiPF 6 The electrolyte 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 uniform mixing, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0239] 4) Isolation parts

[0240] A 16 μm polyethylene film was used as a separator.

[0241] 5) Preparation of battery cell 20

[0242] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is located between the positive and negative electrode sheets to isolate the positive and negative electrodes, and the electrode assembly 23 is wound, and the electrode assembly 23 is placed in an aluminum shell 21, and the electrolyte prepared above is injected into the dried shell 21, and the battery cell 20 is prepared by packaging, standing, forming, shaping, and capacity testing. The shell 21 of the battery cell 20 is a rectangular parallelepiped structure, and the electrode terminal 22 is installed on the first wall 211 of the shell 21, and a pressure relief groove 2111 is provided on the surface of the first wall 211 away from the electrode assembly 23. The pressure relief groove 2111 is in an "H" shape, and the pressure relief groove 2111 is located on one side of the electrode terminal 22 in the first direction Y. Among them, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y of the battery cell 20 of comparative example 3 1 is 5 mm, and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y is 2 is 30 mm so that L 1 With L 2 The ratio is 0.167.

[0243] The preparation methods of the battery cells 20 of Comparative Examples 4-5 and Examples 7-11 are the same as those of Comparative Example 3, except that the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 1 and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y 2 Different, so that L 1 With L 2 The specific situation is shown in Table 2.

[0244] The minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is compared with Examples 3-5 and Examples 7-11. 1 and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y 2 The battery cell 20 is tested under different conditions to obtain the cycle fatigue number of the battery cell 20. The specific experimental method and steps are as follows:

[0245] (1) Prepare a special test fixture. Specifically, the fixture consists of three 10 mm steel plates (a first steel plate, a second steel plate and a third steel plate arranged in sequence along the second direction Z, and the thickness directions of the first steel plate, the second steel plate and the third steel plate are all in the second direction Z). 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 so that the second steel plate can only move in translation along its thickness direction.

[0246] (2) The battery cell 20 is installed between the first steel plate and the second steel plate (i.e., it is placed between the first steel plate and the second steel plate in the second direction Z). A support structure is placed between the largest outer surface of one side of the battery cell 20 and the first steel plate, and between the largest outer surface of the other side of the battery cell 20 and the second steel plate (i.e., support structures are placed on both sides of the battery cell 20 in the second direction Z). The support structure may be a heat insulation pad or a water cooling plate (consistent with the material / structure between the battery cells 20 in the actual battery 100). The support structure may be compressed to provide expansion space for the battery cell 20 during the charge and discharge cycle aging process; the largest outer surface of one side of the battery cell 20 is bonded to the support structure, the first steel plate is bonded to the corresponding support structure, the second steel plate is bonded to the corresponding support structure, and a pressure sensor is provided between the second steel plate and the third steel plate;

[0247] (3) By adjusting the pre-tightening force of the bolts to adjust the position of the second steel plate, and observing the pressure sensor, the battery cell 20 is subjected to an initial extrusion force of 2000N, and the two electrode terminals 22 of the battery cell 20 are connected to a dedicated battery 100 charging and discharging device;

[0248] (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;

[0249] (5) The test steps are carried out in accordance with Chapter 6.4 "Standard Cycle Life" of "GBT31484-2015 Requirements and Test Methods for 100 Cycle Life of Power Batteries for Electric Vehicles", and the test cycle cutoff condition is changed to "stop the test until the area where the pressure relief groove 2111 of the first wall 211 is provided is damaged."

[0250] Specifically, test according to the following steps:

[0251] a. 1I 1 (A) Current discharge to 2.8V;

[0252] b. Leave it for no less than 30 minutes;

[0253] c. Charge according to method 6.1.1.3 of GBT31484-2015 Requirements and test methods for 100 cycle life of power batteries for electric vehicles;

[0254] d. Leave it aside for no less than 30 minutes;

[0255] e. 1I 1 (A) Current discharge to 2.8V;

[0256] f. Repeat steps b to e until the area where the pressure relief groove 2111 of the first wall 211 is provided is damaged, then stop the test.

[0257] That is, the test process continuously observes the area of ​​the first wall 211 where the pressure relief groove 2111 is set until the area of ​​the first wall 211 where the pressure relief groove 2111 is set is damaged and leaks, and the number of cycles is recorded as the number of cycle fatigue times of the battery cell 20, wherein a greater number of cycle fatigue times of the battery cell 20 indicates a lower probability of premature cracking in the area of ​​the first wall 211 where the pressure relief groove 2111 is set during long-term use, and a longer service life, thereby making it possible to reasonably predict the likelihood of premature cracking in the area of ​​the first wall 211 where the pressure relief groove 2111 is set during use through the number of cycle fatigue times of the battery cell 20.

[0258] Among them, the experimental results of Comparative Examples 3-5 and Examples 7-11 are shown in Table 2 below.

[0259] Table 2

[0260]

[0261] As shown in Table 2, based on the experimental results of Comparative Examples 3-5 and Examples 7-11, it can be seen that the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is1 and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y 2 When the ratio is greater than 0.8, the cycle fatigue number of the battery cell 20 is less than 1000 times, so that the area where the pressure relief groove 2111 is set on the first wall 211 of the shell 21 is very likely to crack prematurely during use, thereby causing the battery cell 20 to have a short service life during use. 1 and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y 2 When the ratio of is less than or equal to 0.8, the cycle fatigue number of the battery cell 20 can be close to 1200 times, thereby reducing the phenomenon of premature cracking in the area where the pressure relief groove 2111 is set on the first wall 211 of the shell 21 during use, which is beneficial to improving the service life of the battery cell 20. Therefore, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is set to 1 and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y 2 The ratio is set to be less than or equal to 0.8.

[0262] Similarly, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 1 and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y 2 When the ratio is less than or equal to 0.2, although the cycle fatigue number of the battery cell 20 is higher, the pressure relief groove 2111 is closer to the electrode terminal 22, so that when the first wall 211 is cracked along the pressure relief groove 2111 and releases the internal pressure of the battery cell 20, the thermal runaway gas inside the battery cell 20 is very likely to impact the busbar connected to the electrode terminal 22, thereby causing the insulation layer on the busbar to be damaged, resulting in a short circuit and heat diffusion. Therefore, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is set to 1 and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y 2 The ratio is set to be greater than or equal to 0.2.

[0263] In this embodiment, the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the minimum distance between the pressure relief groove 2111 and the first edge 2112 in the first direction Y is 0.2 to 0.8. On the one hand, by setting the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the minimum distance between the pressure relief groove 2111 and the first edge 2112 in the first direction Y to be less than or equal to 0.8, the pressure relief groove 2111 is closer to the electrode terminal 22 in the first direction Y, so as to enhance the reinforcing effect of the electrode terminal 22 on the structural rigidity of the area where the pressure relief groove 2111 is provided on the first wall 211, which is conducive to reducing the strain and strain amplitude of the area where the pressure relief groove 2111 is provided on the first wall 211, thereby reducing the phenomenon of low cycle fatigue in the area where the pressure relief groove 2111 is provided on the first wall 211, thereby reducing the battery monomer. 20 has a risk of premature valve opening, thereby effectively improving the service life and reliability of the battery cell 20. On the other hand, by setting the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the minimum distance between the pressure relief groove 2111 and the first edge 2112 in the first direction Y to be greater than or equal to 0.2, the phenomenon of the pressure relief groove 2111 being too close to the electrode terminal 22 can be alleviated, so that when the first wall 211 is cracked along at least part of the pressure relief groove 2111 and the internal pressure of the battery cell 20 is released, the impact of the thermal runaway gas inside the battery cell 20 on the electrode terminal 22 and other components connected to the electrode terminal 22 can be reduced, thereby reducing the risk of short circuit or heat diffusion caused by damage to the electrode terminal 22 and other components connected to the electrode terminal 22, so as to improve the reliability of the battery cell 20.

[0264] According to some embodiments of this application, please continue to refer to Figure 5 and Figure 7 As shown, along the first direction Y, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 is L 1 , the minimum distance between the pressure relief groove 2111 and the first edge 2112 is L 2 , satisfying, 0.2≤L 1 / L 2 ≤0.6.

[0265] Please continue to refer to Table 2, and based on the experimental results of Comparative Examples 3-5 and Examples 7-11, it can be seen that the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 1 and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y 2When the ratio of is less than or equal to 0.6, the cycle fatigue times of the battery cell 20 can reach more than 1500 times, thereby further reducing the phenomenon of premature cracking in the area where the pressure relief groove 2111 is set on the first wall 211 of the shell 21, which is beneficial to improving the service life of the battery cell 20. Therefore, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is set to 1 and the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y 2 The ratio of is further set to be less than or equal to 0.6.

[0266] In this embodiment, by further setting the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the minimum distance between the pressure relief groove 2111 and the first edge 2112 in the first direction Y to be less than or equal to 0.6, the pressure relief groove 2111 can be further close to the electrode terminal 22 in the first direction Y, so as to further enhance the reinforcing effect of the electrode terminal 22 on the structural rigidity of the area where the pressure relief groove 2111 is provided on the first wall 211, which is beneficial to reduce the strain and strain amplitude of the area where the pressure relief groove 2111 is provided on the first wall 211, thereby further reducing the phenomenon of low-cycle fatigue in the area where the pressure relief groove 2111 is provided on the first wall 211, so as to further reduce the risk of premature valve opening of the battery cell 20, thereby effectively improving the service life and reliability of the battery cell 20.

[0267] According to some embodiments of the present application, see Figure 5 as well as Figure 7 As shown, the pressure relief groove 2111 and the electrode terminal 22 are arranged along the first direction Y, and the first direction Y is perpendicular to the thickness direction X of the first wall. Along the first direction Y, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 is L 1 The thickness of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is D, satisfying 3≤L 1 / D≤30.

[0268] Among them, the thickness of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 is D (not shown in the figure), which is the dimension of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 along the first direction Y in the thickness direction X of the first wall, and is also the wall thickness of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y.

[0269] 3≤L 1 / D≤30 means that the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the wall thickness of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 3 to 30.

[0270] Exemplarily, the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the wall thickness of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y can be 3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, 12, 12.5, 15, 16, 18, 20, 21, 22, 25, 26, 28, 29 or 30, etc.

[0271] 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 conjunction with Comparative Example 6 and Examples 12-18. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0272] Comparative Example 6

[0273] 1) Preparation of positive electrode

[0274] The positive electrode active material LiNi 0.7 Co 0.1 Mn 0.1 O 2 , conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are used to prepare positive electrode slurry in N-methylpyrrolidone (NMP), wherein the solid content in the positive electrode slurry is 50wt%, and the solid content of LiNi 0.7 Co 0.1 Mn 0.1 O 2 The mass ratio of 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 into pieces, and divided into strips, and then dried at 85°C under vacuum conditions for 4 hours to make the positive electrode sheet.

[0275] 2) Preparation of negative electrode

[0276] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and adhesive styrene butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry is 30wt%, and the mass ratio of graphite, silicon oxide, Super P, CMC and adhesive styrene butadiene rubber (SBR) in the solid component is 88:7:3:2. The negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C, and then cold pressed, trimmed, cut into pieces, and slit, and then dried at 120°C under vacuum conditions for 12 hours to prepare a negative electrode sheet.

[0277] 3) Preparation of electrolyte

[0278] In an argon atmosphere glove box (H 2 O<0.1ppm, O 2 <0.1ppm), the fully dried electrolyte salt LiPF 6 The electrolyte 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 uniform mixing, a liquid electrolyte with a concentration of 1 mol / L was obtained.

[0279] 4) Isolation parts

[0280] A 16 μm polyethylene film was used as a separator.

[0281] 5) Preparation of battery cell 20

[0282] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is located in the middle of the positive and negative electrode sheets to isolate the positive and negative electrodes, and the electrode assembly 23 is wound, and the electrode assembly 23 is placed in an aluminum shell 21, and the electrolyte prepared above is injected into the dried shell 21, and the battery cell 20 is prepared by packaging, standing, forming, shaping, and capacity testing. The shell 21 of the battery cell 20 is a rectangular parallelepiped structure, and the electrode terminal 22 is installed on the first wall 211 of the shell 21, and a pressure relief groove 2111 is provided on the surface of the first wall 211 away from the electrode assembly 23. The pressure relief groove 2111 is in an "H" shape, and the pressure relief groove 2111 is located on one side of the electrode terminal 22 in the first direction Y. Among them, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y of the battery cell 20 of comparative example 6 1 The thickness D of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is 0.8 mm, so that L 1 The ratio to D is 35.

[0283] The preparation method of the battery cell 20 of Examples 12-18 is the same as that of Comparative Example 6, except that the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 1 The thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is different so that L 1 The ratios to D are different, as shown in Table 3.

[0284] The minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is compared with Comparative Example 6 and Examples 12-18. 1 The battery cell 20 is tested under different conditions to obtain the cycle fatigue number of the battery cell 20. The specific experimental method and steps are as follows:

[0285] (1) Prepare a special test fixture. Specifically, the fixture consists of three 10 mm steel plates (a first steel plate, a second steel plate and a third steel plate arranged in sequence along the second direction Z, and the thickness directions of the first steel plate, the second steel plate and the third steel plate are all in the second direction Z). 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 so that the second steel plate can only move in translation along its thickness direction.

[0286] (2) The battery cell 20 is installed between the first steel plate and the second steel plate (i.e., it is placed between the first steel plate and the second steel plate in the second direction Z). A support structure is placed between the largest outer surface of one side of the battery cell 20 and the first steel plate, and between the largest outer surface of the other side of the battery cell 20 and the second steel plate (i.e., support structures are placed on both sides of the battery cell 20 in the second direction Z). The support structure may be a heat insulation pad or a water cooling plate (consistent with the material / structure between the battery cells 20 in the actual battery 100). The support structure may be compressed to provide expansion space for the battery cell 20 during the charge and discharge cycle aging process; the largest outer surface of one side of the battery cell 20 is bonded to the support structure, the first steel plate is bonded to the corresponding support structure, the second steel plate is bonded to the corresponding support structure, and a pressure sensor is provided between the second steel plate and the third steel plate;

[0287] (3) By adjusting the pre-tightening force of the bolts to adjust the position of the second steel plate, and observing the pressure sensor, the battery cell 20 is subjected to an initial extrusion force of 2000N, and the two electrode terminals 22 of the battery cell 20 are connected to a dedicated battery 100 charging and discharging device;

[0288] (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;

[0289] (5) The test steps are carried out in accordance with Chapter 6.4 "Standard Cycle Life" of "GBT31484-2015 Requirements and Test Methods for 100 Cycle Life of Power Batteries for Electric Vehicles", and the test cycle cutoff condition is changed to "stop the test until the area where the pressure relief groove 2111 of the first wall 211 is provided is damaged."

[0290] Specifically, test according to the following steps:

[0291] a. 1I 1 (A) Current discharge to 2.8V;

[0292] b. Leave it for no less than 30 minutes;

[0293] c. Charge according to method 6.1.1.3 of GBT31484-2015 Requirements and test methods for 100 cycle life of power batteries for electric vehicles;

[0294] d. Leave it aside for no less than 30 minutes;

[0295] e. 1I 1 (A) Current discharge to 2.8V;

[0296] f. Repeat steps b to e until the area where the pressure relief groove 2111 of the first wall 211 is provided is damaged, then stop the test.

[0297] That is, the test process continuously observes the area of ​​the first wall 211 where the pressure relief groove 2111 is set until the area of ​​the first wall 211 where the pressure relief groove 2111 is set is damaged and leaks, and the number of cycles is recorded as the number of cycle fatigue times of the battery cell 20, wherein a greater number of cycle fatigue times of the battery cell 20 indicates a lower probability of premature cracking in the area of ​​the first wall 211 where the pressure relief groove 2111 is set during long-term use, and a longer service life, thereby making it possible to reasonably predict the likelihood of premature cracking in the area of ​​the first wall 211 where the pressure relief groove 2111 is set during use through the number of cycle fatigue times of the battery cell 20.

[0298] Among them, the experimental results of Comparative Example 6 and Examples 12-18 are shown in Table 3 below.

[0299] Table 3

[0300] Serial number <![CDATA[L 1 (mm)]]> D(mm) <![CDATA[L 1 / D]]> Cycle fatigue times Thermal runaway results of battery cell 20 Comparative Example 6 28 0.8 35 862 normal Example 12 27 0.9 30 1178 normal Embodiment 13 25 1 25 1517 normal Embodiment 14 24 1.2 20 1732 normal Embodiment 15 22.5 1.5 15 1922 normal Example 16 20 2 10 2325 normal Embodiment 17 15 3 5 2590 normal Embodiment 18 12 4 3 2630 normal

[0301] As shown in Table 3, based on the experimental results of Comparative Example 6 and Examples 12-18, it can be seen that the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 1When the ratio of the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is 35, the cycle fatigue number of the battery cell 20 is less than 1000 times, so that the area of ​​the first wall 211 of the housing 21 where the pressure relief groove 2111 is arranged is very likely to crack prematurely during use, thereby causing the service life of the battery cell 20 to be short during use. 1 When the ratio of the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is less than or equal to 30, the cycle fatigue number of the battery cell 20 can be close to 1200 times, thereby reducing the phenomenon of premature cracking in the area where the pressure relief groove 2111 is set on the first wall 211 of the shell 21 during use, which is beneficial to improving the service life of the battery cell 20. Therefore, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is set to 1 The ratio of the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is set to be less than or equal to 30.

[0302] Similarly, based on Table 3, it can be seen that the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 1 The smaller the ratio of the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22, even when the ratio reaches 3, the change in the number of cycle fatigue times of the battery cell 20 is no longer obvious, but the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y will become smaller and smaller, while the thickness of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 will become larger and larger. Therefore, in order to reduce the phenomenon of excessive waste, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is set to 1 The ratio of the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is set to be greater than or equal to 3.

[0303] In this embodiment, the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the thickness of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 is 3 to 30. On the one hand, by setting the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the thickness of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 to be less than or equal to 30, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is alleviated. The phenomenon that the distance between the pressure relief groove 2111 and the electrode terminal 22 is too large and the thickness of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is too small is conducive to enhancing the structural rigidity of the region where the pressure relief groove 2111 is provided on the first wall 211, thereby reducing the strain and strain amplitude of the region where the pressure relief groove 2111 is provided on the first wall 211, thereby reducing the phenomenon of low-cycle fatigue in the region where the pressure relief groove 2111 is provided on the first wall 211, thereby reducing the risk of premature valve opening of the battery cell 20, and thus being able to have The service life and reliability of the battery cell 20 are effectively improved. On the other hand, by setting the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the thickness of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 to be greater than or equal to 3, the phenomenon that the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is too small and the thickness of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 is too large can be alleviated, thereby alleviating the phenomenon that the thickness of the first wall 211 is excessively wasted, thereby reducing the manufacturing cost of the battery cell 20, and when the first wall 211 is cracked along at least part of the pressure relief groove 2111 and releases the internal pressure of the battery cell 20, the impact of the thermal runaway gas inside the battery cell 20 on the electrode terminal 22 and other components connected to the electrode terminal 22 can be reduced, thereby reducing the risk of short circuit or heat diffusion caused by damage to the electrode terminal 22 and other components connected to the electrode terminal 22, thereby improving the reliability of the battery cell 20.

[0304] According to some embodiments of this application, please continue to refer to Figure 5 and Figure 7 As shown, along the first direction Y, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 is L 1 The thickness of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is D, satisfying that 5≤L 1 / D≤25.

[0305] Please continue to refer to Table 3, and based on the experimental results of Comparative Example 6 and Examples 12-18, it can be seen that the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 1When the ratio of the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is less than or equal to 25, the cycle fatigue times of the battery cell 20 can reach more than 1500 times, thereby further reducing the phenomenon of premature cracking in the area where the pressure relief groove 2111 is set on the first wall 211 of the shell 21 during use, which is beneficial to improving the service life of the battery cell 20. Therefore, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is set to 1 The ratio of the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is further set to be less than or equal to 25. The minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 1 When the ratio of the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is less than 5, the cycle fatigue times of the battery cell 20 are no longer significantly changed. Therefore, in order to reduce the phenomenon of excessive waste, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is set to 1 The ratio of the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is set to be greater than or equal to 5.

[0306] In this embodiment, by setting the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the thickness of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 to be less than or equal to 25, the phenomenon that the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is too large and the thickness of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 is too small is further alleviated, which is beneficial to further enhance the structural rigidity of the region where the pressure relief groove 2111 is provided on the first wall 211 by the electrode terminal 22 and the first wall 211, so as to further reduce the strain and strain amplitude of the region where the pressure relief groove 2111 is provided on the first wall 211, thereby effectively reducing the phenomenon of low cycle fatigue in the region where the pressure relief groove 2111 is provided on the first wall 211, so as to further reduce the battery cell. The risk of premature valve opening of the battery cell 20 is eliminated. Similarly, by setting the ratio of the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to the thickness of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 to be greater than or equal to 5, the phenomenon that the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is too small and the thickness of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is too large can be further alleviated. On the one hand, the phenomenon of excessive waste of the thickness of the first wall 211 can be further alleviated. On the other hand, when the first wall 211 is cracked along at least part of the pressure relief groove 2111 and the internal pressure of the battery cell 20 is released, the impact of the thermal runaway gas inside the battery cell 20 on the electrode terminal 22 and other components connected to the electrode terminal 22 can be further reduced.

[0307] In some embodiments, the thickness of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 is D, satisfying 0.8 mm≤D≤4 mm.

[0308] Exemplarily, the thickness D of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 may be 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 3 mm, 3.5 mm or 4 mm, etc.

[0309] In this embodiment, by setting the thickness of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 to be greater than or equal to 0.8 mm and less than or equal to 4 mm, on the one hand, the structural strength of the portion of the first wall 211 located between the pressure relief groove 2111 and the electrode terminal 22 can be improved to reduce the risk of breakage or damage of the first wall 211 during use; on the other hand, the phenomenon of excessive waste of the thickness of the first wall 211 can be reduced, which is conducive to reducing the manufacturing difficulty and manufacturing cost of the first wall 211.

[0310] According to some embodiments of the present application, see Figure 5 as well as Figure 7 As shown, the pressure relief groove 2111 and the electrode terminal 22 are arranged along the first direction Y, and the first direction Y is perpendicular to the thickness direction X of the first wall. Along the first direction Y, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 is L 1 , meet, 10mm≤L 1 ≤100mm.

[0311] For example, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 is 1 It can be 10mm, 12mm, 15mm, 18mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm or 100mm, etc.

[0312] In this embodiment, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 10 mm to 100 mm. On the one hand, by setting the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to be less than or equal to 100 mm, the pressure relief groove 2111 is closer to the electrode terminal 22, so as to enhance the reinforcing effect of the electrode terminal 22 on the structural rigidity of the area where the pressure relief groove 2111 is provided on the first wall 211, which is beneficial to reduce the strain and strain amplitude of the area where the pressure relief groove 2111 is provided on the first wall 211, thereby reducing the phenomenon of low-cycle fatigue in the area where the pressure relief groove 2111 is provided on the first wall 211, thereby reducing the risk of premature valve opening of the battery cell 20, and thus being able to have The service life and reliability of the battery cell 20 are effectively improved. On the other hand, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is set to be greater than or equal to 10 mm to alleviate the phenomenon that the pressure relief groove 2111 is too close to the electrode terminal 22. Therefore, when the first wall 211 is cracked along at least part of the pressure relief groove 2111 and the internal pressure of the battery cell 20 is released, the impact of the thermal runaway gas inside the battery cell 20 on the electrode terminal 22 and other components connected to the electrode terminal 22 can be reduced, thereby reducing the risk of short circuit or heat diffusion caused by damage to the electrode terminal 22 and other components connected to the electrode terminal 22, thereby improving the reliability of the battery cell 20.

[0313] In some embodiments, see Figure 5 and Figure 7 As shown, along the first direction Y, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 is L 1 , meet, 15mm≤L 1≤50mm.

[0314] In this embodiment, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 15 mm to 50 mm. On the one hand, by further setting the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y to be less than or equal to 50 mm, the pressure relief groove 2111 is closer to the electrode terminal 22, so as to further enhance the structural rigidity of the region where the pressure relief groove 2111 is provided on the first wall 211, which is beneficial to reduce the strain and strain amplitude of the region where the pressure relief groove 2111 is provided on the first wall 211, thereby further reducing the phenomenon of low-cycle fatigue in the region where the pressure relief groove 2111 is provided on the first wall 211, so as to further reduce the risk of premature valve opening of the battery cell 20, thereby effectively The service life and reliability of the battery cell 20 are improved. On the other hand, the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is further set to be greater than or equal to 15 mm, so as to further alleviate the phenomenon that the pressure relief groove 2111 is too close to the electrode terminal 22. When the first wall 211 is cracked along at least part of the pressure relief groove 2111 and the internal pressure of the battery cell 20 is released, the impact of the thermal runaway gas inside the battery cell 20 on the electrode terminal 22 and other components connected to the electrode terminal 22 can be further reduced, thereby further reducing the risk of short circuit or heat diffusion caused by damage to the electrode terminal 22 and other components connected to the electrode terminal 22, so as to improve the reliability of the battery cell 20.

[0315] According to some embodiments of the present application, see Figure 3 , Figure 4 and Figure 5 As shown, the battery cell 20 may include two electrode terminals 22 , both of which are disposed on the first wall 211 , and the two electrode terminals 22 are spaced apart along a first direction Y, and the first direction Y is perpendicular to the thickness direction X of the first wall. Along the first direction Y, the pressure relief groove 2111 is located between the two electrode terminals 22 .

[0316] In which, along the first direction Y, the pressure relief groove 2111 is located between two electrode terminals 22 , that is, one electrode terminal 22 , the pressure relief groove 2111 and the other electrode terminal 22 are arranged in sequence along the first direction Y.

[0317] It should be noted that in other embodiments, only one electrode terminal 22 may be disposed on the first wall 211 , and the other electrode terminal 22 may be disposed on other walls of the shell 21 . That is, the two electrode terminals 22 of the battery cell 20 are disposed on two different walls of the shell 21 .

[0318] In this embodiment, by arranging both electrode terminals 22 of the battery cell 20 on the first wall 211, and arranging the pressure relief groove 2111 between the two electrode terminals 22 in the first direction Y, the two electrode terminals 22 can further enhance the structural rigidity of the region where the pressure relief groove 2111 is provided on the first wall 211, which is beneficial to reduce the strain and strain amplitude of the region where the pressure relief groove 2111 is provided on the first wall 211, thereby further reducing the low-cycle fatigue phenomenon in the region where the pressure relief groove 2111 is provided on the first wall 211, thereby further reducing the risk of premature valve opening of the battery cell 20, and is beneficial to improving the service life and reliability of the battery cell 20.

[0319] According to some embodiments of the present application, see Figure 5 as well as Figure 7 As shown, along the first direction Y, the minimum distance between the pressure relief groove 2111 and the two electrode terminals 22 is equal. That is, the minimum distance L between the pressure relief groove 2111 and any electrode terminal 22 in the first direction Y is equal to 1 are the same.

[0320] In this embodiment, by setting the pressure relief groove 2111 to have an equal spacing with the two electrode terminals 22 in the first direction Y, on the one hand, the regularity of the structure of the battery cell 20 can be improved, which is beneficial to reducing the manufacturing difficulty of the battery cell 20; on the other hand, the two electrode terminals 22 can achieve similar reinforcing effects on the structural rigidity of the area where the pressure relief groove 2111 is provided on the first wall 211, which is beneficial to further reduce the strain and strain amplitude of the area where the pressure relief groove 2111 is provided on the first wall 211, so as to alleviate the phenomenon of low-cycle fatigue in the area where the pressure relief groove 2111 is provided on the first wall 211, thereby further reducing the risk of premature valve opening of the battery cell 20.

[0321] According to some embodiments of the present application, the first wall 211 is provided with a mounting hole (not shown in the figure), the mounting hole penetrates the first wall 211 along the thickness direction X of the first wall, and the mounting hole corresponds to the electrode terminal 22 one by one. The electrode terminal 22 includes a column portion, a first limiting portion and a second limiting portion (not shown in the figure), the column portion is penetrated in the mounting hole along the thickness direction X of the first wall, and the column portion connects the first limiting portion and the second limiting portion, the first limiting portion and the second limiting portion are both protruding from the outer peripheral surface of the column portion, along the thickness direction X of the first wall, the first limiting portion and the second limiting portion are respectively located on both sides of the first wall 211, and at least part of the projection of the first limiting portion and the projection of the second limiting portion overlap with the first wall 211.

[0322] The mounting holes correspond to the electrode terminals 22 one by one, that is, each electrode terminal 22 is installed in one mounting hole.

[0323] The column portion connects the first limiting portion and the second limiting portion, and the first limiting portion and the second limiting portion both protrude from the outer peripheral surface of the column portion, that is, the column portion is a structure extending along the thickness direction X of the first wall and inserted into the mounting hole, and the two ends of the column portion in the thickness direction X of the first wall are respectively connected to the first limiting portion and the second limiting portion, and at the same time, the first limiting portion and the second limiting portion protrude from the outer peripheral surface of the column portion, that is, the projections of the first limiting portion and the second limiting portion in the thickness direction X of the first wall are located on the outside of the column portion.

[0324] The first limiting portion and the second limiting portion are respectively located on both sides of the first wall 211, and the projection of the first limiting portion and the projection of the second limiting portion at least partially overlap with the first wall 211. That is to say, the first limiting portion and the second limiting portion are respectively located on both sides of the first wall 211 and cooperate to clamp the first wall 211 to fasten the electrode terminal 22 to the first wall 211. Exemplarily, insulating parts are provided between the first limiting portion and the second limiting portion and the first wall 211 to make the electrode terminal 22 an insulated structure installed on the first wall 211.

[0325] In this embodiment, the electrode terminal 22 is provided with a first limiting portion, a second limiting portion and a column portion connecting the first limiting portion and the second limiting portion, the column portion is inserted into the mounting hole of the first wall 211, and the first limiting portion and the second limiting portion are respectively located on both sides of the first wall 211 and overlap with at least part of the first wall 211, so as to realize fastening and installation of the electrode terminal 22 on the first wall 211. The electrode terminal 22 adopting such a structure can, on the one hand, improve the structural stability and reliability of the electrode terminal 22 set on the first wall 211, and on the other hand, can further improve the effect of the electrode terminal 22 on reinforcing the structural rigidity of the area where the pressure relief groove 2111 is set on the first wall 211.

[0326] According to some embodiments of the present application, see Figure 4 and Figure 5 As shown, the projection of the first wall 211 in the thickness direction X of the first wall is rectangular, the size of the first wall 211 in the first direction Y is greater than the size of the first wall 211 in the second direction Z, and the thickness direction X of the first wall, the first direction Y and the second direction Z are perpendicular to each other. The pressure relief groove 2111 and the electrode terminal 22 are arranged along the first direction Y.

[0327] Among them, the projection of the first wall 211 in the thickness direction X of the first wall is a rectangle, and the size of the first wall 211 in the first direction Y is greater than the size of the first wall 211 in the second direction Z. That is, the first wall 211 is a rectangular plate structure, and the first direction Y is the length direction of the first wall 211, and the second direction Z is the width direction of the first wall 211.

[0328] The pressure relief groove 2111 and the electrode terminal 22 are arranged along the first direction Y, that is, the pressure relief groove 2111 and the electrode terminal 22 are structures disposed along the length direction of the first wall 211 .

[0329] In this embodiment, the first wall 211 is a rectangular structure. By setting the arrangement direction of the pressure relief groove 2111 and the electrode terminal 22 to be consistent with the length direction of the first wall 211, on the one hand, the difficulty of installing the electrode terminal 22 and setting the pressure relief groove 2111 on the first wall 211 can be reduced, so that the first wall 211 has sufficient space in the first direction Y to set the electrode terminal 22 and the pressure relief groove 2111. On the other hand, the electrode terminal 22 can strengthen the structural rigidity of the first wall 211 in the direction where the first wall 211 is most likely to deform, which is beneficial to further improve the deformation resistance of the first wall 211, so as to reduce the strain and strain amplitude of the area of ​​the first wall 211 where the pressure relief groove 2111 is set, so as to further reduce the phenomenon of low-cycle fatigue in the area of ​​the first wall 211 where the pressure relief groove 2111 is set, so as to further reduce the risk of premature valve opening of the battery cell 20.

[0330] In some embodiments, see Figure 3 , Figure 4 and Figure 5 As shown, the housing 21 is in a rectangular parallelepiped shape, and the housing 21 also has two second walls 214, which are arranged opposite to each other along the second direction Z and are respectively connected to the two ends of the first wall 211. Along the second direction Z, the surface of the second wall 214 away from the electrode assembly 23 is the surface with the largest area among the outer surfaces of the housing 21.

[0331] The second walls 214 are two walls of the housing 21 respectively connected to two ends of the first wall 211 in the second direction Z, and the two second walls 214 are arranged at intervals along the second direction Z and are parallel to each other.

[0332] The surface of the second wall 214 facing away from the electrode assembly 23 is the surface with the largest area among the outer surfaces of the outer shell 21, that is, the length direction and width direction of the second wall 214 are respectively the length direction and width direction of the outer shell 21 of the battery cell 20, so that the arrangement direction of the two second walls 214 is the thickness direction of the battery cell 20, that is, the second direction Z is the thickness direction of the battery cell 20.

[0333] In this embodiment, the shell 21 is in the shape of a rectangular parallelepiped, and the shell 21 also has two second walls 214 arranged opposite to each other in the second direction Z, and the surface of the second wall 214 facing away from the electrode assembly 23 is the surface with the largest area in the outer surface of the shell 21, so that the second direction Z is both the width direction of the first wall 211 and the thickness direction of the battery cell 20, so that the electrode terminal 22 can strengthen the structural rigidity of the first wall 211 in the direction where the deformation of the first wall 211 is the largest, which is beneficial to further improve the deformation resistance of the first wall 211, so as to reduce the strain and strain amplitude of the area where the pressure relief groove 2111 is provided on the first wall 211, so as to further reduce the phenomenon of low-cycle fatigue in the area where the pressure relief groove 2111 is provided on the first wall 211, so as to further reduce the risk of premature valve opening of the battery cell 20.

[0334] According to some embodiments of the present application, the pressure relief groove 2111 is stamped on the first wall 211. In other words, the pressure relief groove 2111 is a groove structure formed on the first wall 211 by a stamping process.

[0335] It should be noted that, in other embodiments, the pressure relief groove 2111 formed on the first wall 211 may also be formed by a processing technique such as laser etching or milling.

[0336] In this embodiment, by setting the pressure relief groove 2111 as a structure formed by stamping on the first wall 211 , the pressure relief groove 2111 is formed on the first wall 211 in a simple manner, which is beneficial to reducing the manufacturing cost of the battery cell 20 .

[0337] According to some embodiments of the present application, referring to Figure 6 , and please refer to Figure 8 , Figure 8 A partial cross-sectional view of a first wall 211 of a housing 21 of a battery cell 20 provided in some embodiments of the present application. The pressure relief groove 2111 includes a plurality of grooves arranged in sequence along the thickness direction X of the first wall. In other words, the pressure relief groove 2111 is a multi-step groove structure arranged along the thickness direction X of the first wall, that is, the pressure relief groove 2111 is a step groove structure formed by multiple stampings.

[0338] For example, in Figure 8 In the embodiment, the pressure relief groove 2111 is a two-stage stepped groove structure, that is, the pressure relief groove 2111 includes two-stage grooves arranged in sequence along the thickness direction X of the first wall. Of course, in other embodiments, the pressure relief groove 2111 can also be a three-stage stepped groove, a four-stage stepped groove, a five-stage stepped groove or a six-stage stepped groove, etc.

[0339] It should be noted that in the embodiment where the pressure relief groove 2111 includes a plurality of groove sections, each groove section is a multi-stage stepped groove structure. Figure 6In the embodiment, the pressure relief groove 2111 includes a first groove section 2111a and two second groove sections 2111b, and the first groove section 2111a and the two second groove sections 2111b are both multi-step groove structures. Of course, when the pressure relief groove 2111 is a curve, loop or straight line extending along a smooth trajectory, the pressure relief groove 2111 is a multi-step groove structure.

[0340] In this embodiment, the pressure relief groove 2111 is arranged as a multi-step stepped groove structure arranged along the thickness direction X of the first wall, so that the pressure relief groove 2111 is a groove structure formed by multiple processing. The pressure relief groove 2111 with such a structure can reduce the depth of the single processing of the pressure relief groove 2111 under the condition of the same depth, which is beneficial to reduce the manufacturing difficulty of the pressure relief groove 2111 and the demand for manufacturing equipment, so as to reduce the manufacturing cost, and can reduce the forming force exerted on the first wall 211 during the single processing of the pressure relief groove 2111, which is beneficial to reduce the risk of cracks in the first wall 211, so as to improve the production quality of the battery cell 20, and can improve the flow shape of the pressure relief groove 2111 during the formation process, which is beneficial to the flow of the material generated when the pressure relief groove 2111 is formed, so as to improve the structural consistency of the pressure relief groove 2111.

[0341] In some embodiments, see Figure 8 As shown, along the thickness direction X of the first wall, the minimum residual thickness of the pressure relief groove 2111 is D 3 , meet, 0.05mm≤D 3 ≤0.3mm.

[0342] Among them, the minimum residual thickness D of the pressure relief groove 2111 is 3 The first wall 211 is provided with a pressure relief groove 2111 and the minimum thickness of the area corresponding to the groove bottom surface of the pressure relief groove 2111 in the thickness direction X of the first wall. Figure 8 In the embodiment, the bottom of the pressure relief groove 2111 forms a first weak portion 2111c, and the minimum residual thickness D of the pressure relief groove 2111 is 3 Then the minimum thickness of the first weak portion 2111c in the thickness direction X of the first wall is D 3 .

[0343] For example, in Figure 8 In the case of a multi-stage groove of the pressure relief groove 2111, the minimum residual thickness D of the pressure relief groove 2111 is 3 It is the thickness of the bottom wall of the deepest primary groove of the pressure relief groove 2111 in the thickness direction X of the first wall.

[0344] For example, the minimum residual thickness D of the pressure relief groove 2111 is 3It can be 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.12mm, 0.15mm, 0.16mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm or 0.3mm, etc.

[0345] In the present embodiment, the minimum residual thickness of the pressure relief groove 2111 in the thickness direction X of the first wall is 0.05 mm to 0.3 mm. On the one hand, by setting the minimum residual thickness of the pressure relief groove 2111 in the thickness direction X of the first wall to be greater than or equal to 0.05 mm, the problem of too low structural strength of the area of ​​the first wall 211 where the pressure relief groove 2111 is provided can be alleviated, thereby reducing the risk of cracking or damage in the area of ​​the first wall 211 where the pressure relief groove 2111 is provided during production, transportation or normal use. On the other hand, by setting the minimum residual thickness of the pressure relief groove 2111 in the thickness direction X of the first wall to be less than or equal to 0.3 mm, the problem of the difficulty of the first wall 211 to crack along the pressure relief groove 2111 when the battery cell 20 has thermal runaway can be alleviated, thereby reducing the bursting pressure required for the pressure relief valve opening of the battery cell 20, thereby reducing the risk of explosion of the battery cell 20 caused by excessive pressure relief bursting pressure.

[0346] In some embodiments, the battery cell 20 may further include an electrolyte, which is contained in the housing 21. The electrolyte includes an electrolyte salt, which includes hexafluorophosphate, and the molar concentration of the hexafluorophosphate is less than or equal to 1.1 mol / L.

[0347] Illustratively, the molar concentration of hexafluorophosphate in the electrolyte can be 0.1 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L or 1.1 mol / L, etc.

[0348] It should be noted that the hexafluorophosphate in the electrolyte is easily oxidized or reduced during use to generate unstable compounds and acidic substances, such as hydrofluoric acid, which is a common one. Hydrofluoric acid is a highly corrosive inorganic acid and has a strong corrosive effect on the shell 21.

[0349] In this embodiment, by setting the molar concentration of hexafluorophosphate in the electrolyte to be less than or equal to 1.1 mol / L, the amount of hydrofluoric acid generated by the battery cell 20 during use can be reduced, thereby reducing the corrosion of the area where the pressure relief groove 2111 is provided on the first wall 211, thereby alleviating the further reduction in the minimum residual thickness of the pressure relief groove 2111, and thereby reducing the risk of premature cracking or damage of the battery cell 20 due to the decrease in structural strength of the area where the pressure relief groove 2111 is provided on the first wall 211, thereby further improving the reliability and stability of the battery cell 20.

[0350] According to some embodiments of the present application, see Figure 5 , Figure 6 and Figure 8 As shown, the bottom of the pressure relief groove 2111 forms a first weak portion 2111c, and the first wall 211 is configured to be able to split along at least part of the first weak portion 2111c when the battery cell 20 releases pressure. The first wall 211 is also provided with a guide groove 2114, and the bottom of the guide groove 2114 forms a second weak portion 2114a. Along the thickness direction X of the first wall, the projection of the pressure relief groove 2111 and the projection of at least one guide groove 2114 jointly define at least one predetermined pressure relief area 2113, and the second weak portion 2114a is configured to guide at least part of the predetermined pressure relief area 2113 to flip, so as to open at least part of the predetermined pressure relief area 2113.

[0351] Among them, a first weak portion 2111c is formed at the bottom of the pressure relief groove 2111, and the first wall 211 is configured to be able to split along at least part of the first weak portion 2111c when the battery cell 20 releases pressure. That is to say, the bottom wall of the pressure relief groove 2111 is the first weak portion 2111c, and the first weak portion 2111c is the remaining portion of the first wall 211 where the pressure relief groove 2111 is set, so that the first wall 211 can be split along at least part of the bottom wall of the pressure relief groove 2111 when the battery cell 20 releases pressure, thereby releasing the internal pressure of the battery cell 20.

[0352] The bottom of the guide groove 2114 forms a second weak portion 2114 a , that is, the bottom wall of the guide groove 2114 is the second weak portion 2114 a , and the second weak portion 2114 a is the remaining portion of the first wall 211 where the guide groove 2114 is set.

[0353] Along the thickness direction X of the first wall, the projection of the pressure relief groove 2111 and the projection of at least one guide groove 2114 jointly define at least one predetermined pressure relief area 2113, that is, at least one predetermined pressure relief area 2113 is formed in the area enclosed by the pressure relief groove 2111 and the guide groove 2114. Figure 6In the embodiment, the pressure relief groove 2111 and the guide groove 2114 define two predetermined pressure relief areas 2113, and the two predetermined pressure relief areas 2113 are arranged at intervals along the second direction Z. The pressure relief groove 2111 is a structure arranged along the edge of the predetermined pressure relief area 2113, so that the arrangement trajectory of the pressure relief groove 2111 is arranged along the edge of the predetermined pressure relief area 2113, so that the first wall 211 can be split along the edge of the predetermined pressure relief area 2113.

[0354] It should be noted that, in the embodiment where the pressure relief groove 2111 and the guide groove 2114 are spaced apart from each other and do not contact each other, the predetermined pressure relief area 2113 is an area enclosed by the projection of the pressure relief groove 2111 in the thickness direction X of the first wall, the projection of the extension line of the pressure relief groove 2111 in the thickness direction X of the first wall, the projection of the guide groove 2114 in the thickness direction X of the first wall, and the projection of the extension of the guide groove 2114 in the thickness direction X of the first wall. Optionally, the pressure relief groove 2111 may include only one groove segment, or may be a structure formed by connecting multiple groove segments. Similarly, the pressure relief groove 2111 and the guide groove 2114 may be grooves extending along a straight trajectory, or may be grooves extending along a non-straight trajectory.

[0355] The second weak portion 2114a is configured to guide at least a portion of the predetermined pressure relief zone 2113 to flip over so as to open at least a portion of the predetermined pressure relief zone 2113. That is, after the first wall 211 is cracked along the first weak portion 2111c at the bottom of the pressure relief groove 2111 and the predetermined pressure relief zone 2113 is opened, at least a portion of the predetermined pressure relief zone 2113 can be flipped around the second weak portion 2114a as the axis, so that after the predetermined pressure relief zone 2113 is flipped over, the interior of the outer shell 21 and the exterior of the outer shell 21 are connected to each other for pressure relief.

[0356] In the present embodiment, a guide groove 2114 is further provided on the first wall 211. The projection of the guide groove 2114 and the pressure relief groove 2111 along the thickness direction X of the first wall defines at least one predetermined pressure relief area 2113 on the first wall 211. The predetermined pressure relief area 2113 can be opened after the first wall 211 is at least partially cracked along the pressure relief groove 2111, and can be flipped around the second weak portion 2114a at the bottom of the guide groove 2114 to release the internal pressure of the battery cell 20. The battery cell 20 adopting this structure can expand the flipping angle of the predetermined pressure relief area 2113 after the predetermined pressure relief area 2113 is opened, thereby effectively increasing the pressure relief area of ​​the battery cell 20, so as to improve the pressure relief rate of the battery cell 20 when thermal runaway occurs, thereby reducing the risk of fire and explosion of the battery cell 20 due to untimely pressure relief, which is beneficial to improving the reliability of the battery cell 20.

[0357] According to some embodiments of the present application, see Figure 6 and Figure 8 As shown, the pressure relief groove 2111 and the electrode terminal 22 are arranged along the first direction Y, the pressure relief groove 2111 and the guide groove 2114 are arranged along the second direction Z, and the thickness direction X of the first wall, the first direction Y and the second direction Z are perpendicular to each other.

[0358] Among them, the pressure relief groove 2111 and the electrode terminal 22 are arranged along the first direction Y, and the pressure relief groove 2111 and the guide groove 2114 are arranged along the second direction Z. That is, in the second direction Z, at least one side of the pressure relief groove 2111 is provided with a guide groove 2114, and the guide groove 2114 can be a structure that is in contact with or spaced apart from the pressure relief groove 2111.

[0359] For example, in Figure 6 In the figure, the pressure relief groove 2111 defines two predetermined pressure relief areas 2113 arranged at intervals along the second direction Z. Correspondingly, guide grooves 2114 are provided on both sides of the pressure relief groove 2111 in the second direction Z, so that the pressure relief groove 2111 is located between the two guide grooves 2114 in the second direction Z, and each predetermined pressure relief area 2113 corresponds to a guide groove 2114.

[0360] In this embodiment, by setting the guide groove 2114 and the pressure relief groove 2111 as a structure arranged along the second direction Z, the guide groove 2114 is located on at least one side of the pressure relief groove 2111 in the second direction Z. On the one hand, the influence of the guide groove 2114 on the structural rigidity of the area of ​​the first wall 211 located between the electrode terminal 22 and the pressure relief groove 2111 can be reduced, which is beneficial to enhance the reinforcing effect of the electrode terminal 22 on the structural rigidity of the area of ​​the first wall 211 where the pressure relief groove 2111 is provided. On the other hand, the interference influence between the pressure relief groove 2111 and the guide groove 2114 can be reduced, so as to facilitate the processing of the pressure relief groove 2111 and the guide groove 2114 respectively, and can alleviate the phenomenon that the first weak portion 2111c at the bottom of the pressure relief groove 2111 tears the second weak portion 2114a at the bottom of the guide groove 2114 when cracking, and can also enhance the effect of the predetermined pressure relief area 2113 being flipped around the second weak portion 2114a after being opened.

[0361] In some embodiments, see Figure 5 and Figure 6 As shown, the pressure relief groove 2111 and the guide groove 2114 are arranged at intervals along the second direction Z. That is, the orthographic projections of the pressure relief groove 2111 and the guide groove 2114 in a plane perpendicular to the thickness direction X of the first wall are arranged at intervals along the second direction Z, so that the projection of the pressure relief groove 2111 in the thickness direction X of the first wall and the projection of the guide groove 2114 in the thickness direction X of the first wall are arranged at intervals along the second direction Z, that is, the guide groove 2114 is located on one side of the pressure relief groove 2111 in the second direction Z, and there is a gap between the two.

[0362] For example, in Figure 6 In the embodiment, the first wall 211 is provided with two guide grooves 2114, which are arranged at intervals along the second direction Z and are respectively located on both sides of the pressure relief groove 2111 in the second direction Z. The two guide grooves 2114 and the pressure relief groove 2111 are arranged at intervals in the second direction Z.

[0363] In this embodiment, by setting the pressure relief groove 2111 and the guide groove 2114 as a structure arranged at intervals along the second direction Z, the pressure relief groove 2111 and the guide groove 2114 are not in contact with each other. On the one hand, the mutual influence between the pressure relief groove 2111 and the guide groove 2114 during the processing can be reduced, and the stress influence between the area of ​​the first wall 211 where the pressure relief groove 2111 is set and the area of ​​the first wall 211 where the guide groove 2114 is set can be reduced. On the other hand, the phenomenon that the first weak portion 2111c at the bottom of the pressure relief groove 2111 tears the second weak portion 2114a at the bottom of the guide groove 2114 when it is cracked can be further alleviated, which is beneficial to enhance the effect of the predetermined pressure relief area 2113 flipping around the second weak portion 2114a.

[0364] According to some embodiments of the present application, see Figure 5 and Figure 6 As shown, the guide groove 2114 extends along the first direction Y, and along the first direction Y, two ends of the guide groove 2114 extend out of two end portions of the pressure relief groove 2111 respectively.

[0365] Among them, along the first direction Y, the two ends of the guide groove 2114 extend out of the two end parts of the pressure relief groove 2111 respectively, that is, the size of the guide groove 2114 in the first direction Y is larger than the pressure relief groove 2111, and the two ends of the guide groove 2114 in the first direction Y extend out of the two sides of the pressure relief groove 2111 respectively, that is, in the embodiment where the pressure relief groove 2111 includes a first groove section 2111a and two second groove sections 2111b, the two ends of the guide groove 2114 in the first direction Y extend out of the two sides of the two second groove sections 2111b respectively.

[0366] In this embodiment, along the thickness direction X of the first wall, by setting the projection of the guide groove 2114 in its extension direction to extend respectively to the two ends of the projection of the pressure relief groove 2111, the guide groove 2114 is a structure in which both ends in its extension direction respectively exceed the two ends of the pressure relief groove 2111. On the one hand, the size of the guide groove 2114 in its extension direction is larger than the pressure relief groove 2111, so that the predetermined pressure relief area 2113 defined by the pressure relief groove 2111 can be turned around the second weak portion 2114a, and the predetermined pressure relief area 2113 defined by the pressure relief groove 2111 can be lifted. The flipping effect of the pressure zone 2113 can increase the pressure relief area of ​​the battery cell 20, thereby improving the pressure relief rate of the battery cell 20 when thermal runaway occurs. On the other hand, it can improve the absorption effect of the guide groove 2114 on the residual material squeezed out of the pressure relief groove 2111 of the first wall 211 during the molding process, and can improve the separation effect of the guide groove 2114 between the edge of the pressure relief groove 2111 and the first wall 211, so as to improve the blocking effect of the guide groove 2114 on the deformation energy of the battery cell 20 when the battery cell 20 is subjected to internal and external impact forces.

[0367] In some embodiments, along the thickness direction X of the first wall, the projection of the guide groove 2114 does not overlap with the projection of the electrode terminal 22 .

[0368] In this embodiment, by setting the projections of the guide groove 2114 and the electrode terminal 22 in the thickness direction X of the first wall to be non-overlapping structures, the interference between the guide groove 2114 and the electrode terminal 22 can be reduced, which is beneficial to reducing the manufacturing difficulty of the battery cell 20.

[0369] According to some embodiments of the present application, see Figure 6 and Figure 8 As shown, along the thickness direction X of the first wall, the thickness of the second weak portion 2114a is greater than the thickness of the first weak portion 2111c, that is, the residual thickness of the guide groove 2114 is greater than the residual thickness of the pressure relief groove 2111, that is, in the thickness direction X of the first wall, the thickness of the bottom wall of the guide groove 2114 is greater than the thickness of the bottom wall of the pressure relief groove 2111, that is, in the thickness direction X of the first wall, the depth of the pressure relief groove 2111 is greater than the depth of the guide groove 2114.

[0370] It should be noted that, if the pressure relief groove 2111 includes an embodiment in which the pressure relief groove 2111 includes multiple smooth groove sections, the first weak portion 2111c includes multiple weak sections, and the bottom wall of each groove section of the pressure relief groove 2111 is a weak section of the first weak portion 2111c; if the pressure relief groove 2111 includes only one smooth groove section in an embodiment, the first weak portion 2111c includes only one weak section.

[0371] In this embodiment, by setting the thickness of the second weak portion 2114a in the thickness direction X of the first wall to be greater than the thickness of the first weak portion 2111c in the thickness direction X of the first wall, so that the residual thickness of the guide groove 2114 is greater than the residual thickness of the pressure relief groove 2111, the structural strength of the area of ​​the first wall 211 where the pressure relief groove 2111 is set is less than the structural strength of the area of ​​the first wall 211 where the guide groove 2114 is set, so that the first wall 211 can preferentially crack along the first weak portion 2111c at the bottom of the pressure relief groove 2111 and release the internal pressure of the battery cell 20, which helps to alleviate the phenomenon that the first wall 211 cracks from the area where the guide groove 2114 is set, causing poor pressure relief effect of the battery cell 20.

[0372] In some embodiments, see Figure 6 and Figure 8 As shown, along the thickness direction X of the first wall, the thickness of the second weak portion 2114a is D 4 , meet, 0.15mm≤D 4 ≤0.5mm.

[0373] The thickness D of the second weak portion 2114a is 4 The thickness of the first wall 211 in the thickness direction X of the first wall is the area where the guide groove 2114 is provided and the bottom surface of the guide groove 2114 corresponds to.

[0374] For example, in Figure 8 In the example, the guide groove 2114 is a primary groove, and the thickness D of the second weak portion 2114a is 4 is the thickness of the bottom wall of the guide groove 2114 in the thickness direction X of the first wall. Of course, if the pressure relief groove 2111 is a multi-stage groove structure, the thickness D of the second weak portion 2114a is 4 It is the wall thickness of the bottom wall of the deepest primary groove of the guide groove 2114 in the thickness direction X of the first wall.

[0375] For example, the thickness D of the second weak portion 2114a is 4 It can be 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm or 0.5mm, etc.

[0376] In this embodiment, the thickness of the second weak portion 2114a in the thickness direction X of the first wall is 0.15 mm to 0.5 mm. On the one hand, by setting the thickness of the second weak portion 2114a in the thickness direction X of the first wall to be greater than or equal to 0.15 mm, the structural strength of the region where the guide groove 2114 is provided on the first wall 211 is improved, so as to alleviate the phenomenon of the first wall 211 being accidentally cracked in the region where the guide groove 2114 is provided when the battery cell 20 has thermal runaway, so as to improve the reliability and stability of the battery cell 20. On the other hand, by The thickness of 14a in the thickness direction X of the first wall is set to be less than or equal to 0.5mm, so as to alleviate the phenomenon that the thickness of the second weak portion 2114a is too large, resulting in poor effect of flipping around the second weak portion 2114a after the predetermined pressure relief area 2113 is opened, thereby being able to further expand the flipping angle of the predetermined pressure relief area 2113 to increase the pressure relief area of ​​the battery cell 20, which is beneficial to improving the pressure relief rate of the battery cell 20 when thermal runaway occurs, and further reducing the risk of fire and explosion of the battery cell 20 due to untimely pressure relief, so as to improve the reliability of the battery cell 20.

[0377] According to some embodiments of the present application, see Figure 6 and Figure 8 As shown, the first weak portion 2111c includes at least one weak section, and the cross-sectional area of ​​the weak section perpendicular to its extension direction is a first cross-sectional area S 1 The cross-sectional area of ​​the second weak portion 2114a perpendicular to its extension direction is the second cross-sectional area S 2 , meet, S 1 <S 2 .

[0378] For example, in Figure 6 In the embodiment, the pressure relief groove 2111 includes three groove sections, and the corresponding first weak portion 2111c includes three weak sections, and the bottom of each groove section of the pressure relief groove 2111 forms a weak section.

[0379] Among them, the first cross-sectional area S 1 The first cross-sectional area S is the product of the width of the weak section in the direction perpendicular to the extension direction of the weak section and the thickness direction X of the first wall and the thickness of the weak section in the thickness direction X of the first wall. If the weak section is a structure extending along the first direction Y, the first cross-sectional area S 1 is the product of the width of the weak section in the second direction Z and the thickness of the weak section in the thickness direction X of the first wall; if the weak section is a structure extending along the second direction Z, the first cross-sectional area S 1 It is the product of the width of the weak section in the first direction Y and the thickness of the weak section in the thickness direction X of the first wall.

[0380] The second cross-sectional area S 2is the product of the width of the second weak portion 2114a in a direction perpendicular to the extension direction of the second weak portion 2114a and the thickness direction X of the first wall and the thickness of the second weak portion 2114a in the thickness direction X of the first wall. Figure 6 In the embodiment, the guide groove 2114 is a structure extending along the first direction Y, and correspondingly, the second weak portion 2114a formed at the bottom of the guide groove 2114 is a structure extending along the first direction Y, so the second cross-sectional area S 2 It is the product of the width of the second weak portion 2114a in the second direction Z and the thickness of the second weak portion 2114a in the thickness direction X of the first wall.

[0381] In this embodiment, by setting the area of ​​the cross section of the weak section of the first weak portion 2111c perpendicular to its extension direction to be smaller than the area of ​​the cross section of the second weak portion 2114a perpendicular to its extension direction, the structural strength of the area where the pressure relief groove 2111 is set on the first wall 211 is smaller than the structural strength of the area where the guide groove 2114 is set on the first wall 211, thereby facilitating the first wall 211 to preferentially crack along the first weak portion 2111c at the bottom of the pressure relief groove 2111 and release the internal pressure of the battery cell 20, which helps to alleviate the phenomenon that the first wall 211 cracks from the area where the guide groove 2114 is set, causing poor pressure relief effect of the battery cell 20.

[0382] According to some embodiments of the present application, see Figure 6 and Figure 8 As shown, along the thickness direction X of the first wall, the pressure relief groove 2111 and the guide groove 2114 are respectively arranged on both sides of the first wall 211. That is, the pressure relief groove 2111 and the guide groove 2114 are respectively arranged on the surface of the first wall 211 on both sides in the thickness direction X of the first wall.

[0383] Optionally, the pressure relief groove 2111 may be disposed on the side of the first wall 211 facing the interior of the housing 21, and correspondingly, the guide groove 2114 is disposed on the side of the first wall 211 away from the interior of the housing 21. Of course, the pressure relief groove 2111 may also be disposed on the side of the first wall 211 away from the interior of the housing 21, and correspondingly, the guide groove 2114 is disposed on the side of the first wall 211 facing the interior of the housing 21. In other embodiments, the pressure relief groove 2111 and the guide groove 2114 may be both located on the same side of the first wall 211 in the thickness direction X of the first wall.

[0384] For example, in Figure 8 In the embodiment, the groove side of the guide groove 2114 and the groove bottom of the guide groove 2114 are set at an obtuse angle to facilitate processing to form the guide groove 2114. Similarly, the groove side of the pressure relief groove 2111 and the groove bottom of the pressure relief groove 2111 are set at an obtuse angle to facilitate processing to form the pressure relief groove 2111. Figure 8 In the embodiment, the pressure relief groove 2111 is a multi-level groove structure arranged along the thickness direction X of the first wall, that is, the pressure relief groove 2111 is a stepped groove structure, and the groove side surface and the groove bottom surface of each level of the groove are arranged at an obtuse angle.

[0385] In this embodiment, the pressure relief groove 2111 and the guide groove 2114 are respectively arranged on both sides of the first wall 211 in the thickness direction X of the first wall, thereby facilitating the processing of the pressure relief groove 2111 and the guide groove 2114 on both sides of the first wall 211, which is beneficial to reducing the mutual influence of the pressure relief groove 2111 and the guide groove 2114 during the processing.

[0386] In some embodiments, see Figure 6 and Figure 8 As shown, along the thickness direction X of the first wall, the pressure relief groove 2111 is disposed on the side of the first wall 211 away from the electrode assembly 23. That is, the pressure relief groove 2111 is disposed on the outer surface of the first wall 211 away from the inside of the housing 21.

[0387] In this embodiment, the pressure relief groove 2111 is arranged on the side of the first wall 211 away from the electrode assembly 23, so that the pressure relief groove 2111 is arranged on the outer surface of the first wall 211, thereby facilitating the formation of the pressure relief groove 2111 on the first wall 211, which is beneficial to reducing the processing difficulty of the pressure relief groove 2111 and improving the production efficiency of the battery cell 20.

[0388] In some embodiments, see Figure 6 and Figure 8 As shown, along the thickness direction X of the first wall, the guide groove 2114 is provided on the side of the first wall 211 facing the electrode assembly 23. That is, the guide groove 2114 is provided on the inner surface of the first wall 211 facing the inside of the housing 21.

[0389] In this embodiment, the guide groove 2114 is arranged on the side of the first wall 211 facing the electrode assembly 23, so that the guide groove 2114 is arranged on the inner surface of the first wall 211, so that the predetermined pressure relief zone 2113 can be flipped toward the outside of the outer shell 21 after the second weak portion 2114a around the bottom of the guide groove 2114 is opened, thereby reducing the interference effect of the groove side of the guide groove 2114 on the predetermined pressure relief zone 2113 during the flipping process, which is beneficial to improving the flipping effect of the predetermined pressure relief zone 2113.

[0390] According to some embodiments of the present application, see Figure 5 and Figure 6 as well as Figure 7As shown, the pressure relief groove 2111 includes a first groove section 2111a and two second groove sections 2111b. The two second groove sections 2111b are arranged opposite to each other along the first direction Y, and the second groove sections 2111b and the guide groove 2114 are arranged along the second direction Z. The first groove section 2111a connects the two second groove sections 2111b, and the thickness direction X of the first wall, the first direction Y and the second direction Z are perpendicular to each other. Along the thickness direction X of the first wall, the projection of the first groove section 2111a, the projection of the two second groove sections 2111b, the projection of the extension lines of the two second groove sections 2111b, and the projection of the guide groove 2114 together enclose a predetermined pressure relief area 2113; or, along the thickness direction X of the first wall, the projection of the first groove section 2111a, the projection of the two second groove sections 2111b, the projection of the guide groove 2114, and the projection of the extension line of the guide groove 2114 together enclose a predetermined pressure relief area 2113; or, along the thickness direction X of the first wall, the projection of the first groove section 2111a, the projection of the two second groove sections 2111b, the projection of the extension lines of the two second groove sections 2111b, the projection of the guide groove 2114, and the projection of the extension line of the guide groove 2114 together enclose a predetermined pressure relief area 2113.

[0391] The two second slot sections 2111b are arranged opposite to each other along the first direction Y, that is, the two second slot sections 2111b are arranged at intervals along the first direction Y. Figure 6 and Figure 7 In the embodiment, the two second slot sections 2111b both extend along the second direction Z.

[0392] It should be noted that in the embodiment where the pressure relief groove 2111 includes a first groove section 2111a and two second groove sections 2111b, see Figure 5 As shown, the minimum distance L between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is 1 is the minimum distance L between the second groove section 2111b and the electrode terminal 22 in the first direction Y. Similarly, the minimum distance L between the pressure relief groove 2111 and the first edge 2112 in the first direction Y is 2 It is the minimum distance between the second slot section 2111b and the first edge 2112 in the first direction Y.

[0393] The first slot segment 2111a connects the two second slot segments 2111b, that is, the first slot segment 2111a is located between the two second slot segments 2111b in the first direction Y, and the two ends of the first slot segment 2111a are respectively connected to the two second slot segments 2111b. Of course, in other embodiments, the first slot segment 2111a can also extend two second slot segments 2111b at both ends in the first direction Y.

[0394] For example, in Figure 6 and Figure 7In the embodiment, the predetermined pressure relief zone 2113 is an area enclosed by the projection of the first groove segment 2111a on the thickness direction X of the first wall, the projection of the two second groove segments 2111b on the thickness direction X of the first wall, the projection of the extension lines of the two second groove segments 2111b on the thickness direction X of the first wall, and the projection of the guide groove 2114 on the thickness direction X of the first wall, and the first groove segment 2111a and the two second groove segments 2111b are structures arranged along the edge of the predetermined pressure relief zone 2113, so that the predetermined pressure relief zone 2113 can be opened with the first groove segment 2111a and the two second groove segments 2111b as boundaries, that is, the portion of the first wall 211 located in the predetermined pressure relief zone 2113 can be opened with the first groove segment 2111a and the two second groove segments 2111b as boundaries when the battery cell 20 is depressurized, thereby releasing the internal pressure of the battery cell 20. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the predetermined pressure relief area 2113 may also be an area jointly formed by the projection of the first groove segment 2111a in the thickness direction X of the first wall, the projection of the two second groove segments 2111b in the thickness direction X of the first wall, the projection of the guide groove 2114 in the thickness direction X of the first wall, and the projection of the extension line of the guide groove 2114 in the thickness direction X of the first wall. It can also be an area jointly formed by the projection of the first groove segment 2111a in the thickness direction X of the first wall, the projection of the two second groove segments 2111b in the thickness direction X of the first wall, the projection of the extension line of the two second groove segments 2111b in the thickness direction X of the first wall, the projection of the guide groove 2114 in the thickness direction X of the first wall, and the projection of the extension line of the guide groove 2114 in the thickness direction X of the first wall.

[0395] Alternatively, see Figure 5 and Figure 6 As shown, the pressure relief groove 2111 formed by the first groove section 2111a and the two second groove sections 2111b may be in an "H"-shaped structure, and two guide grooves 2114 are provided on the first wall 211, and the two guide grooves 2114 are respectively located on both sides of the pressure relief groove 2111 in the second direction Z, so as to form two predetermined pressure relief areas 2113 on the first wall 211, and the two predetermined pressure relief areas 2113 are respectively located on both sides of the first groove section 2111a in the second direction Z. Of course, in other embodiments, the pressure relief groove 2111 may also be in other shapes, for example, one end of the two second groove sections 2111b is respectively connected to the two ends of the first groove section 2111a, so as to enclose and form a predetermined pressure relief area 2113 on the first wall 211, so that the pressure relief groove 2111 formed by the first groove section 2111a and the two second groove sections 2111b is in a "U"-shaped structure.

[0396] In the present embodiment, the battery cell 20 adopting such a structure makes it easy to process the pressure relief groove 2111 on the first wall 211 and form the predetermined pressure relief area 2113, and the predetermined pressure relief area 2113 defined by the pressure relief groove 2111 of such a structure is easier to flip around the position where the guide groove 2114 is located. On the other hand, the intersection of the first groove section 2111a and the second groove section 2111b is weaker and easier to crack and open the predetermined pressure relief area 2113 for pressure relief.

[0397] In some embodiments, see Figure 5 and Figure 6 As shown, the first wall 211 is provided with two guide grooves 2114, and along the second direction Z, the first groove section 2111a is located between the two guide grooves 2114. The connection positions of the two second groove sections 2111b and the first groove section 2111a are both offset from the two ends of the two second groove sections 2111b, so that predetermined pressure relief areas 2113 are formed on both sides of the first groove section 2111a along the second direction Z.

[0398] Among them, the connection positions of the two second groove sections 2111b and the first groove section 2111a are deviated from the two ends of the two second groove sections 2111b, that is, the first groove section 2111a is connected between the two ends of the second groove section 2111b, so that the shape of the pressure relief groove 2111 formed by the first groove section 2111a and the two second groove sections 2111b is an approximately "H"-shaped structure, so that the pressure relief groove 2111 and the guide groove 2114 define two predetermined pressure relief areas 2113 on the first wall 211, and the two predetermined pressure relief areas 2113 are respectively located on both sides of the first groove section 2111a in the second direction Z.

[0399] Along the second direction Z, the two guide grooves 2114 are respectively located on both sides of the pressure relief groove 2111, that is, guide grooves 2114 are arranged on both sides of the pressure relief groove 2111 in the second direction Z, and each guide groove 2114 corresponds to a predetermined pressure relief area 2113, so that each guide groove 2114 can guide the corresponding predetermined pressure relief area 2113 to flip.

[0400] In this embodiment, the connection positions of the two second groove sections 2111b and the first groove section 2111a are set to be located between the two ends of the corresponding second groove sections 2111b, so that the first groove section 2111a and the two second groove sections 2111b form a pressure relief groove 2111 similar to an "H"-shaped structure, so that predetermined pressure relief areas 2113 can be formed on both sides of the first groove section 2111a of the pressure relief groove 2111, and the two predetermined pressure relief areas 2113 can be opened in a split manner for pressure relief when the battery cell 20 is depressurized, which is beneficial to further increase the pressure relief effect of the battery cell 20 and can effectively improve the pressure relief rate of the battery cell 20.

[0401] In some embodiments, reference Fig. 9 , Fig. 9 A front view of a battery cell 20 provided in some other embodiments of the present application facing the pressure relief groove 2111 in the thickness direction X of the first wall. One end of a second groove section 2111b is connected to one end of the first groove section 2111a, and one end of another second groove section 2111b is connected to the other end of the first groove section 2111a. In other words, one end of the two second groove sections 2111b is respectively connected to the two ends of the first groove section 2111a, so that the shape of the pressure relief groove 2111 formed by the first groove section 2111a and the two second groove sections 2111b is a "U"-shaped structure.

[0402] In this embodiment, a second groove segment 2111b, a first groove segment 2111a and another second groove segment 2111b are arranged to be connected in sequence, so that the first groove segment 2111a and the two second groove segments 2111b constitute a pressure relief groove 2111 of a "U"-shaped structure, which is beneficial to reducing the processing difficulty of the pressure relief groove 2111 and is beneficial to expanding the area of ​​the predetermined pressure relief zone 2113, so that after the predetermined pressure relief zone 2113 is opened, the pressure relief area of ​​the battery cell 20 can be increased to improve the pressure relief rate of the battery cell 20.

[0403] According to some embodiments of the present application, see Figure 5 as well as Fig. 9 As shown, the first slot segment 2111a and the two second slot segments 2111b extend along a straight line, and the first slot segment 2111a is perpendicular to the two second slot segments 2111b. In other words, the extension direction of the first slot segment 2111a is perpendicular to the extension direction of the second slot segment 2111b.

[0404] It should be noted that, in the embodiment where the connection positions of the two second slot segments 2111b and the first slot segment 2111a deviate from the two ends of the two second slot segments 2111b, the shape of the pressure relief groove 2111 formed by the first slot segment 2111a and the two second slot segments 2111b is a regular "H"-shaped structure, and predetermined pressure relief areas 2113 are formed on both sides of the first slot segment 2111a along the second direction Z. Of course, the areas of the two predetermined pressure relief areas 2113 may be the same or different.

[0405] Exemplarily, the first slot segment 2111a is a straight structure extending along the first direction Y, the second slot segment 2111b is a straight structure extending along the second direction Z, and the first slot segment 2111a is located along the first direction Y between the two second slot segments 2111b.

[0406] In this embodiment, by setting the two second groove sections 2111b to be perpendicular to the first groove section 2111a, the extension direction of the first groove section 2111a is made to be the arrangement direction of the two second groove sections 2111b, thereby improving the regularity of the shape of the pressure relief groove 2111, which is beneficial to reducing the processing difficulty of the pressure relief groove 2111, thereby reducing the manufacturing cost of the battery cell 20 and improving the production efficiency of the battery cell 20.

[0407] According to some embodiments of the present application, referring to Fig.10 , Fig.10 The battery cell 20 provided in some other embodiments of the present application is a front view of the pressure relief groove 2111 in the thickness direction X of the first wall. The pressure relief groove 2111 includes a first groove section 2111a and a second groove section 2111b, and the first groove section 2111a and the second groove section 2111b are connected. Along the thickness direction X of the first wall, the projection of the first groove section 2111a, the projection of the extension line of the first groove section 2111a, the projection of the second groove section 2111b, the projection of the extension line of the second groove section 2111b and the projection of the guide groove 2114 together enclose a predetermined pressure relief area 2113; or, along the thickness direction X of the first wall, the projection of the first groove section 2111a, the projection of the second groove section 2111b, the projection of the guide groove 2114 and the projection of the extension line of the guide groove 2114 together enclose a predetermined pressure relief area 2113; or, along the thickness direction X of the first wall, the projection of the first groove section 2111a, the projection of the extension line of the first groove section 2111a, the projection of the second groove section 2111b, the projection of the extension line of the second groove section 2111b, the projection of the guide groove 2114 and the projection of the extension line of the guide groove 2114 together enclose a predetermined pressure relief area 2113.

[0408] Among them, one end of the first slot section 2111a is connected to one end of the second slot section 2111b, so that the first slot section 2111a and the second slot section 2111b form a "V"-shaped pressure relief groove 2111. Correspondingly, the pressure relief groove 2111 only defines one predetermined pressure relief area 2113, and the first wall 211 is only provided with one guide groove 2114, and the guide groove 2114 is provided corresponding to the predetermined pressure relief area 2113. Of course, in other embodiments, the shape of the pressure relief groove 2111 formed by the first slot section 2111a and the second slot section 2111b being connected to each other may also be a "T"-shaped structure, an "L"-shaped structure, an "X"-shaped structure, etc.

[0409] For example, in Fig.10In the figure, the predetermined pressure relief area 2113 is an area enclosed by the projection of the first groove segment 2111a on the thickness direction X of the first wall, the projection of the extension line of the first groove segment 2111a on the thickness direction X of the first wall, the projection of the second groove segment 2111b on the thickness direction X of the first wall, the projection of the extension line of the second groove segment 2111b on the thickness direction X of the first wall and the projection of the guide groove 2114 on the thickness direction X of the first wall. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the predetermined pressure relief area 2113 may also be an area enclosed by the projection of the first groove segment 2111a in the thickness direction X of the first wall, the projection of the second groove segment 2111b in the thickness direction X of the first wall, the projection of the guide groove 2114 in the thickness direction X of the first wall, and the projection of the extension line of the guide groove 2114 in the thickness direction X of the first wall. It can also be an area enclosed by the projection of the first groove segment 2111a in the thickness direction X of the first wall, the projection of the extension line of the first groove segment 2111a in the thickness direction X of the first wall, the projection of the second groove segment 2111b in the thickness direction X of the first wall, the projection of the extension line of the second groove segment 2111b in the thickness direction X of the first wall, the projection of the guide groove 2114 in the thickness direction X of the first wall, and the projection of the extension line of the guide groove 2114 in the thickness direction X of the first wall.

[0410] In this embodiment, by setting the pressure relief groove 2111 to include a first groove section 2111a and a second groove section 2111b that are interconnected, the battery cell 20 with this structure can, on the one hand, increase the pressure relief area of ​​the battery cell 20 to increase the pressure relief rate of the battery cell 20, and on the other hand, make the intersection of the first groove section 2111a and the second groove section 2111b weaker and easier to crack and open the predetermined pressure relief area 2113 to release the internal pressure of the battery cell 20.

[0411] According to some embodiments of the present application, referring to Fig.11 , Fig.11 A front view of a battery cell 20 provided in some other embodiments of the present application facing the pressure relief groove 2111 in the thickness direction X of the first wall. The pressure relief groove 2111 is a groove extending along an arc track. Along the thickness direction X of the first wall, the projection of the pressure relief groove 2111, the projection of the extension line of the pressure relief groove 2111 and the projection of the guide groove 2114 together enclose a predetermined pressure relief area 2113; or, along the thickness direction X of the first wall, the projection of the pressure relief groove 2111, the projection of the guide groove 2114 and the projection of the extension line of the guide groove 2114 together enclose a predetermined pressure relief area 2113; or, along the thickness direction X of the first wall, the projection of the pressure relief groove 2111, the projection of the extension line of the pressure relief groove 2111, the projection of the guide groove 2114 and the projection of the extension line of the guide groove 2114 together enclose a predetermined pressure relief area 2113.

[0412] The pressure relief groove 2111 is a groove extending along an arc-shaped track, that is, the pressure relief groove 2111 only includes a smooth groove section, and the pressure relief groove 2111 is an arc-shaped groove structure.

[0413] For example, in Fig.11 In the embodiment, the predetermined pressure relief area 2113 is a region enclosed by the projection of the pressure relief groove 2111 in the thickness direction X of the first wall, the projection of the extension line of the pressure relief groove 2111 in the thickness direction X of the first wall, and the projection of the guide groove 2114 in the thickness direction X of the first wall. Of course, the structure of the battery cell 20 is not limited thereto. In other embodiments, the predetermined pressure relief area 2113 may also be a region enclosed by the projection of the pressure relief groove 2111 in the thickness direction X of the first wall, the projection of the guide groove 2114 in the thickness direction X of the first wall, and the projection of the extension line of the guide groove 2114 in the thickness direction X of the first wall, or may be a region enclosed by the projection of the pressure relief groove 2111 in the thickness direction X of the first wall, the projection of the extension line of the pressure relief groove 2111 in the thickness direction X of the first wall, the projection of the guide groove 2114 in the thickness direction X of the first wall, and the projection of the extension line of the guide groove 2114 in the thickness direction X of the first wall.

[0414] For example, in Fig.11 In the embodiment, the pressure relief groove 2111 is in a "C" shape.

[0415] In this embodiment, the pressure relief groove 2111 is set as a structure extending along an arc trajectory so that the predetermined pressure relief area 2113 is formed on the inner side of the pressure relief groove 2111. The pressure relief groove 2111 with this structure is easy to manufacture on the first wall 211, which is beneficial to reduce the manufacturing difficulty of the battery cell 20.

[0416] In some embodiments, the guide groove 2114 is stamped on the first wall 211. In other words, the guide groove 2114 is a groove structure formed on the first wall 211 by a stamping process.

[0417] It should be noted that, in other embodiments, the guide groove 2114 formed on the first wall 211 may also be formed by a processing technique such as laser etching or milling.

[0418] In this embodiment, by setting the guide groove 2114 as a structure formed by stamping on the first wall 211 , the forming method of the guide groove 2114 on the first wall 211 is simple, which is beneficial to reducing the manufacturing cost of the battery cell 20 .

[0419] According to some embodiments of the present application, along the thickness direction X of the first wall, the first wall 211 is configured to support the electrode assembly 23. That is, in the thickness direction X of the first wall, the first wall 211 of the housing 21 is located at the bottom of the electrode assembly 23, and the thickness direction X of the first wall is the gravity direction or an approximate gravity direction.

[0420] In this embodiment, the first wall 211 can support the electrode assembly 23 in the thickness direction X of the first wall, so that the battery cell 20 is a structure that can be placed inverted. On the one hand, it enables the battery cell 20 to adapt to more usage scenarios to improve the adaptability of the battery cell 20. On the other hand, it can achieve that the pressure relief groove 2111 and the electrode terminal 22 of the battery cell 20 are both located at the bottom of the battery cell 20, so as to facilitate assembly and the release of the internal pressure of the battery cell 20.

[0421] According to some embodiments of the present application, see Figure 3 and Figure 4 As shown, the housing 21 may include a shell 212 and an end cap 213 , wherein the shell 212 has an accommodation cavity with an opening 2121 formed inside, and the accommodation cavity is used to accommodate the electrode assembly 23 , and the end cap 213 closes the opening 2121 , and the end cap 213 is a first wall 211 .

[0422] The end cover 213 is the first wall 211 , that is, the pressure relief groove 2111 is disposed on the end cover 213 of the outer shell 21 , and correspondingly, the electrode terminal 22 is also disposed on the end cover 213 of the outer shell 21 .

[0423] In this embodiment, by setting the first wall 211 of the outer shell 21 as the end cover 213 of the outer shell 21 for closing the opening 2121, the battery cell 20 adopting this structure is convenient for setting the pressure relief groove 2111 and installing the electrode terminal 22 on the end cover 213, which is beneficial to reduce the manufacturing difficulty of the battery cell 20 and improve the production efficiency of the battery cell 20.

[0424] It should be noted that the structure of the battery cell 20 is not limited thereto. In some embodiments, the battery cell 20 may also be other structures. For example, the housing 21 may include a shell 212 and an end cover 213. The shell 212 has an accommodating cavity with an opening 2121 formed inside. The accommodating cavity is used to accommodate the electrode assembly 23. The end cover 213 closes the opening 2121. The shell 212 includes a first wall 211.

[0425] The housing 212 includes an integrally formed side wall and bottom wall, that is, the housing 212 is manufactured by an integral molding process, such as an integral molding process such as stamping, casting or extrusion molding, that is, the side wall and bottom wall of the housing 212 are an integral structure. Correspondingly, the housing 212 includes a first wall 211, that is, the first wall 211 can be the bottom wall of the housing 212, or one of the multiple walls of the side wall of the housing 212.

[0426] In this embodiment, by setting the first wall 211 of the outer shell 21 as a wall of the shell 212, the battery cell 20 adopting this structure can make the area of ​​the outer shell 21 where the pressure relief groove 2111 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 area of ​​the first wall 211 where the pressure relief groove 2111 is provided, so as to reduce the impact on the area of ​​the first wall 211 where the pressure relief groove 2111 is provided, and further help to reduce the risk of cracking or structural strength reduction in the area of ​​the first wall 211 where the pressure relief groove 2111 is provided under the pulling action of stress, so as to improve the service life and reliability of the battery cell 20.

[0427] It should be noted that the structure of the battery cell 20 can be various. In some embodiments, the outer shell 21 may include a shell 212 and two end covers 213. The shell 212 has a housing cavity formed inside, which is used to accommodate the electrode assembly 23. Openings 2121 are formed at opposite ends of the shell 212, and the two openings 2121 are connected to the housing cavity. The two end covers 213 respectively close the two openings 2121, and one of the two end covers 213 is a first wall 211.

[0428] In this embodiment, the shell 212 of the outer shell 21 is provided with an opening 2121 structure at both opposite ends, and the two end covers 213 respectively close the two openings 2121, and the first wall 211 is one of the two end covers 213. The battery cell 20 adopting this structure is convenient for assembling the battery cell 20 from both ends of the shell 212, which is beneficial to reducing the manufacturing difficulty and assembly difficulty of the battery cell 20, and is convenient to set the pressure relief groove 2111 and install the electrode terminal 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.

[0429] Of course, the structure of the battery cell 20 is not limited thereto. In the embodiment where the outer shell 21 includes a shell 212 and two end caps 213, the shell 212 may include a first wall 211, that is, the first wall 211 is a wall in the shell 212. The battery cell 20 with such a structure can make the area of ​​the outer shell 21 where the pressure relief groove 2111 is provided away from the end cap 213, thereby effectively alleviating the stress generated by the connection between the end cap 213 and the shell 212 acting on the area of ​​the first wall 211 where the pressure relief groove 2111 is provided, so as to reduce the impact on the area of ​​the first wall 211 where the pressure relief groove 2111 is provided, thereby facilitating reducing the risk of cracking or structural strength reduction in the area of ​​the first wall 211 where the pressure relief groove 2111 is provided under the pulling action of stress, so as to improve the service life and reliability of the battery cell 20.

[0430] According to some embodiments of the present application, the present application further provides a battery 100, and the battery 100 includes a battery cell 20 of any of the above schemes.

[0431] In some embodiments, see Figure 2 As shown, the battery 100 may further include a box body 10 , in which the battery cell 20 is accommodated. The box body 10 has a bottom plate located at the bottom of the battery cell 20 , and along the thickness direction X of the first wall, the bottom plate and the first wall 211 are arranged facing each other.

[0432] Among them, the box body 10 has a bottom plate located at the bottom of the battery cell 20, and along the thickness direction X of the first wall, the bottom plate and the first wall 211 are arranged facing each other, that is, the bottom plate is a plate of the box body 10 located at the bottom of the battery cell 20 in the thickness direction X of the first wall, and the first wall 211 is arranged opposite to the bottom plate, that is, the first wall 211 is also located at the bottom of the electrode assembly 23 in the thickness direction X of the first wall, and the thickness direction X of the first wall is the gravity direction or the approximate gravity direction, so that the battery cell 20 is placed inverted in the box body 10 at one end where the electrode terminal 22 and the pressure relief groove 2111 are provided.

[0433] Optionally, the box body 10 may include a first box body 11 and a second box body 12, the first box body 11 and the second box body 12 cover each other, and the first box body 11 and the second box body 12 jointly define an assembly space for accommodating the battery cell 20. Figure 2 In the embodiment, the bottom plate is a plate body of the second box body 12.

[0434] Optionally, the second box body 12 can be a hollow structure with one end open, and the first box body 11 can be a plate-like structure. The first box body 11 covers the open side of the second box body 12, so that the first box body 11 and the second box body 12 jointly define an assembly space; the first box body 11 and the second box body 12 can also be hollow structures both with one side open, and the open side of the first box body 11 covers the open side of the second box body 12.

[0435] 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 cuboid. Figure 2 In the embodiment, the box body 10 is a rectangular parallelepiped structure.

[0436] Optionally, the number of battery cells 20 disposed in the box body 10 may be one or more. Figure 2 In the embodiment, a plurality of battery cells 20 are arranged in the box 10 of the battery 100, and the plurality of battery cells 20 can be connected in series, in parallel or in a mixed connection. The mixed connection means that the plurality of battery cells 20 are both connected in series and in parallel. The plurality of battery cells 20 can be directly connected in series, in parallel or in a mixed connection, and then the whole formed by the plurality of battery cells 20 is accommodated in the box 10; of course, the battery 100 can also be a battery module formed by first connecting the plurality of battery cells 20 in series, in parallel or in a mixed connection, and then the plurality of battery modules are connected in series, in parallel or in a mixed connection to form a whole, and then accommodated in the box 10.

[0437] The battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, which connects the plurality of battery cells 20 to achieve electrical connection between the plurality of battery cells 20 .

[0438] It should be noted that, in some embodiments, the battery 100 may not be provided with a box 10, and the battery 100 includes a plurality of battery cells 20, and the battery 100 composed of a plurality of battery cells 20 may be directly assembled on an electrical device to provide electrical energy to the electrical device through the plurality of battery cells 20. In other words, the box 10 may be used as a part of the electrical device. Taking the vehicle 1000 as an example of the electrical device, the box 10 may be used as a part of the chassis structure of the vehicle 1000, for example, a part of the box 10 may become at least a part of the floor of the vehicle 1000, or a part of the box 10 may become at least a part of the crossbeam and longitudinal beam of the vehicle 1000.

[0439] In this embodiment, the bottom plate of the box body 10 and the first wall 211 of the battery cell 20 are arranged facing each other in the thickness direction X of the first wall, so that the battery cell 20 is an inverted structure arranged in the box body 10, so that the pressure relief groove 2111 and the electrode terminal 22 of the battery cell 20 are both located at the bottom of the battery cell 20 and facing the bottom plate, so as to facilitate assembly and release of the internal pressure of the battery cell 20, and can alleviate the risk of upward impact of thermal runaway gas released from the battery cell 20 of the battery 100 during thermal runaway to the user.

[0440] According to some embodiments of the present application, the present application further provides an electrical device, which includes the battery cell 20 or the battery 100 of any of the above schemes, and the battery cell 20 is used to provide electrical energy to the electrical device.

[0441] The electrical device may be any of the aforementioned devices or systems using the battery cell 20 or the battery 100 .

[0442] According to some embodiments of the present application, see Figures 3 to 8 As shown, the present application provides a battery cell 20, which includes a shell 21, two electrode terminals 22 and an electrode assembly 23. The shell 21 is in the shape of a rectangular parallelepiped, and the shell 21 has a first wall 211. The shell 21 includes a shell 212 and an end cover 213. The shell 212 has an accommodating cavity with an opening 2121 formed inside, and the accommodating cavity is used to accommodate the electrode assembly 23. The end cover 213 closes the opening 2121, and the end cover 213 is the first wall 211. Both electrode terminals 22 are arranged on the first wall 211, and the thickness of the electrode terminals 22 in the thickness direction X of the first wall is greater than the wall thickness of the first wall 211, and they are arranged at intervals along the first direction Y. The electrode assembly 23 is accommodated in the shell 21, and the electrode assembly 23 is electrically connected to the electrode terminal 22. The first wall 211 is provided with a pressure relief groove 2111, which is formed by stamping on the first wall 211. The pressure relief groove 2111 includes a plurality of grooves arranged in sequence along the thickness direction X of the first wall. The bottom of the pressure relief groove 2111 forms a first weak portion 2111c. The first wall 211 is configured to be able to split along at least part of the first weak portion 2111c when the battery cell 20 is depressurized to release the internal pressure of the battery cell 20. Along the thickness direction X of the first wall, the projection of the pressure relief groove 2111 does not overlap with the projection of the electrode terminal 22. Along the first direction Y, the pressure relief groove 2111 is provided between the two electrode terminals 22. Along the second direction Z, the maximum dimension of the electrode terminal 22 is D 1 , the maximum dimension of the first wall 211 is D 2 , satisfying, 0.6≤D 1 / D 2≤0.9, the thickness direction X of the first wall, the first direction Y and the second direction Z are perpendicular to each other. The outer edge of the first wall 211 includes a first edge 2112, the first edge 2112 and the pressure relief groove 2111 are respectively located on both sides of the electrode terminal 22 in the first direction Y, and the minimum distance between the pressure relief groove 2111 and the electrode terminal 22 along the first direction Y is L 1 , the minimum distance between the pressure relief groove 2111 and the first edge 2112 is L 2 , satisfying, 0.2≤L 1 / L 2 ≤0.6,15mm≤L 1 ≤50mm. The thickness of the portion of the first wall 211 between the pressure relief groove 2111 and the electrode terminal 22 in the first direction Y is D, satisfying that 5≤L 1 / D≤25. The projection of the first wall 211 in the thickness direction X of the first wall is rectangular, the size of the first wall 211 in the first direction Y is greater than the size of the first wall 211 in the second direction Z, and the shell 21 also has two second walls 214, the two second walls 214 are arranged opposite to each other along the second direction Z and are respectively connected to the two ends of the first wall 211, and along the second direction Z, the surface of the second wall 214 away from the electrode assembly 23 is the largest surface of the outer surface of the shell 21. The pressure relief groove 2111 includes a first groove section 2111a and two second groove sections 2111b, the two second groove sections 2111b are arranged opposite to each other along the first direction Y, and the second groove sections 2111b and the guide groove 2114 are arranged along the second direction Z, the first groove section 2111a connects the two second groove sections 2111b, and the connection positions of the two second groove sections 2111b and the first groove section 2111a are deviated from the two ends of the two second groove sections 2111b, so as to form a predetermined pressure relief groove on both sides of the first groove section 2111a along the second direction Z. In the area 2113, the first wall 211 is provided with two guide grooves 2114, which are formed by stamping on the first wall 211, and the bottom of the guide groove 2114 forms a second weak portion 2114a. Along the second direction Z, the two guide grooves 2114 are respectively located on both sides of the pressure relief groove 2111, and the second weak portion 2114a is configured to guide at least part of the predetermined pressure relief area 2113 to flip so as to open at least part of the predetermined pressure relief area 2113. The pressure relief groove 2111 and the guide groove 2114 are spaced apart along the second direction Z. The first groove section 2111a and the two second groove sections 2111b extend along a straight line trajectory, and the first groove section 2111a is perpendicular to the two second groove sections 2111b. Along the thickness direction X of the first wall, the thickness of the second weak portion 2114a is greater than the thickness of the first weak portion 2111c. The first weak portion 2111c includes at least one weak section, and the cross-sectional area of ​​the weak section perpendicular to its extension direction is the first cross-sectional area S 1 The cross-sectional area of ​​the second weak portion 2114a perpendicular to its extension direction is the second cross-sectional area S 2, meet, S 1 <S 2 Along the thickness direction X of the first wall, the pressure relief groove 2111 and the guide groove 2114 are respectively arranged on both sides of the first wall 211 , the pressure relief groove 2111 is arranged on the side of the first wall 211 away from the electrode assembly 23 , and the guide groove 2114 is arranged on the side of the first wall 211 facing the electrode assembly 23 .

[0443] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

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

Claims

1. A battery cell, characterized in that: include: a housing having a first wall; an electrode terminal, disposed on the first wall; as well as an electrode assembly, contained in the housing, the electrode assembly being electrically connected to the electrode terminal; The first wall is provided with a pressure relief groove, and the first wall is configured to be able to split along at least a portion of the pressure relief groove when the battery cell is depressurized, and along the thickness direction of the first wall, the projection of the pressure relief groove does not overlap with the projection of the electrode terminal, and the thickness of the electrode terminal is greater than the thickness of the first wall.

2. The battery cell according to claim 1, characterized in that: The pressure relief groove and the electrode terminal are arranged along a first direction; Wherein, along the second direction, the maximum dimension of the electrode terminal is D1, the maximum dimension of the first wall is D2, and 0.4≤D1 / D2≤0.9 is satisfied, and the thickness direction of the first wall, the first direction and the second direction are perpendicular to each other.

3. The battery cell according to claim 2, characterized in that: 0.6≤D1 / D2≤0.

9.

4. The battery cell according to claim 1, characterized in that: The outer edge of the first wall includes a first edge, the first edge and the pressure relief groove are respectively located on both sides of the electrode terminal in a first direction, and the first direction is perpendicular to the thickness direction of the first wall; Wherein, along the first direction, the minimum distance between the pressure relief groove and the electrode terminal is L1, and the minimum distance between the pressure relief groove and the first edge is L2, satisfying 0.2≤L1 / L2≤0.

8.

5. The battery cell according to claim 4, characterized in that: 0.2≤L1 / L2≤0.

6.

6. The battery cell according to claim 1, characterized in that: The pressure relief grooves and the electrode terminals are arranged along a first direction, and the first direction is perpendicular to a thickness direction of the first wall; Wherein, along the first direction, the minimum distance between the pressure relief groove and the electrode terminal is L1, and the thickness of the portion of the first wall between the pressure relief groove and the electrode terminal is D, satisfying 3≤L1 / D≤30.

7. The battery cell according to claim 6, characterized in that: 5≤L1 / D≤25.

8. The battery cell according to claim 6, characterized in that: 0.8mm≤D≤4mm.

9. The battery cell according to claim 1, characterized in that: The pressure relief grooves and the electrode terminals are arranged along a first direction, and the first direction is perpendicular to a thickness direction of the first wall; Wherein, along the first direction, the minimum distance between the pressure relief groove and the electrode terminal is L1, which satisfies 10mm≤L1≤100mm.

10. The battery cell according to claim 9, characterized in that: 15mm≤L1≤50mm.

11. The battery cell according to claim 1, characterized in that: The battery cell includes two electrode terminals, both of which are disposed on the first wall, and the two electrode terminals are arranged at intervals along a first direction, and the first direction is perpendicular to a thickness direction of the first wall; Wherein, along the first direction, the pressure relief groove is located between the two electrode terminals.

12. The battery cell according to claim 11, characterized in that: Along the first direction, the minimum distance between the pressure relief groove and the two electrode terminals is equal.

13. The battery cell according to claim 1, characterized in that: The first wall is provided with a mounting hole, the mounting hole penetrates the first wall along the thickness direction of the first wall, and the mounting hole corresponds to the electrode terminal one by one; Among them, the electrode terminal includes a column portion, a first limiting portion and a second limiting portion, the column portion is penetrated into the mounting hole along the thickness direction of the first wall, and the column portion connects the first limiting portion and the second limiting portion, the first limiting portion and the second limiting portion both protrude from the outer circumferential surface of the column portion, along the thickness direction of the first wall, the first limiting portion and the second limiting portion are respectively located on both sides of the first wall, and at least part of the projection of the first limiting portion and the projection of the second limiting portion overlap with the first wall.

14. The battery cell according to claim 1, characterized in that: The projection of the first wall in the thickness direction of the first wall is rectangular, the size of the first wall in the first direction is greater than the size of the first wall in the second direction, and the thickness direction of the first wall, the first direction and the second direction are perpendicular to each other; Wherein, the pressure relief groove and the electrode terminal are arranged along the first direction.

15. The battery cell according to claim 14, characterized in that: The housing is in a rectangular parallelepiped shape, and the housing further has two second walls, the two second walls are arranged opposite to each other along the second direction and are respectively connected to two ends of the first wall; Wherein, along the second direction, the surface of the second wall facing away from the electrode assembly is the surface with the largest area among the outer surfaces of the shell.

16. The battery cell according to claim 1, characterized in that: The pressure relief groove is stamped and formed on the first wall.

17. The battery cell according to claim 1, characterized in that: The pressure relief groove includes a plurality of grooves sequentially arranged along the thickness direction of the first wall.

18. The battery cell according to claim 1, characterized in that: Along the thickness direction of the first wall, the minimum residual thickness of the pressure relief groove is D3, which satisfies 0.05 mm ≤ D3 ≤ 0.3 mm.

19. The battery cell according to claim 18, characterized in that: The battery cell further includes an electrolyte, which is contained in the housing; Wherein, the electrolyte includes an electrolyte salt, the electrolyte salt includes hexafluorophosphate, and the molar concentration of the hexafluorophosphate is less than or equal to 1.1 mol / L.

20. The battery cell according to any one of claims 1 to 19, characterized in that: A first weak portion is formed at the bottom of the pressure relief groove, and the first wall is configured to be able to be split along at least a portion of the first weak portion when the battery cell releases pressure; Among them, the first wall is also provided with a guide groove, the bottom of the guide groove forms a second weak portion, along the thickness direction of the first wall, the projection of the pressure relief groove and the projection of at least one of the guide grooves jointly define at least one predetermined pressure relief area, and the second weak portion is configured to guide at least part of the predetermined pressure relief area to flip over so as to open at least part of the predetermined pressure relief area.

21. The battery cell according to claim 20, characterized in that: The pressure relief groove and the electrode terminal are arranged along a first direction, the pressure relief groove and the guide groove are arranged along a second direction, and the thickness direction of the first wall, the first direction and the second direction are perpendicular to each other.

22. The battery cell according to claim 21, characterized in that: The guide groove extends along the first direction, and along the first direction, two ends of the guide groove extend out of two end portions of the pressure relief groove respectively.

23. The battery cell according to claim 22, characterized in that: Along the thickness direction of the first wall, a projection of the guide groove does not overlap with a projection of the electrode terminal.

24. The battery cell according to claim 20, characterized in that: Along the thickness direction of the first wall, the thickness of the second weak portion is greater than the thickness of the first weak portion.

25. The battery cell according to claim 20, characterized in that: The first weak portion includes at least one weak section, the cross-sectional area of ​​the weak section perpendicular to its extension direction is a first cross-sectional area S1, and the cross-sectional area of ​​the second weak portion perpendicular to its extension direction is a second cross-sectional area S2, satisfying S1<S2.

26. The battery cell according to claim 20, characterized in that: Along the thickness direction of the first wall, the pressure relief groove and the guide groove are respectively arranged on both sides of the first wall.

27. The battery cell according to claim 20, characterized in that: The pressure relief groove includes a first groove section and two second groove sections, the two second groove sections are arranged opposite to each other along a first direction, and the second groove sections and the guide groove are arranged along a second direction, the first groove section connects the two second groove sections, and the thickness direction of the first wall, the first direction and the second direction are perpendicular to each other; Wherein, along the thickness direction of the first wall, the projection of the first groove segment, the projection of the two second groove segments, the projection of the extended lines of the two second groove segments and the projection of the guide groove jointly enclose the predetermined pressure relief area; or Along the thickness direction of the first wall, the projection of the first groove segment, the projection of the two second groove segments, the projection of the guide groove and the projection of the extension line of the guide groove jointly enclose the predetermined pressure relief area; or Along the thickness direction of the first wall, the projection of the first groove segment, the projection of the two second groove segments, the projection of the extension lines of the two second groove segments, the projection of the guide groove and the projection of the extension line of the guide groove jointly enclose the predetermined pressure relief area.

28. The battery cell according to claim 20, characterized in that: The pressure relief groove comprises a first groove section and a second groove section, wherein the first groove section and the second groove section are connected; Wherein, along the thickness direction of the first wall, the projection of the first groove segment, the projection of the extension line of the first groove segment, the projection of the second groove segment, the projection of the extension line of the second groove segment and the projection of the guide groove together enclose the predetermined pressure relief area; or Along the thickness direction of the first wall, the projection of the first groove segment, the projection of the second groove segment, the projection of the guide groove and the projection of the extension line of the guide groove jointly enclose the predetermined pressure relief area; or Along the thickness direction of the first wall, the projection of the first groove segment, the projection of the extension line of the first groove segment, the projection of the second groove segment, the projection of the extension line of the second groove segment, the projection of the guide groove and the projection of the extension line of the guide groove together enclose the predetermined pressure relief area.

29. The battery cell according to claim 20, characterized in that: The pressure relief groove is a groove extending along an arc track; Wherein, along the thickness direction of the first wall, the projection of the pressure relief groove, the projection of the extended line of the pressure relief groove and the projection of the guide groove jointly enclose the predetermined pressure relief area; or Along the thickness direction of the first wall, the projection of the pressure relief groove, the projection of the guide groove and the projection of the extension line of the guide groove jointly enclose the predetermined pressure relief area; or Along the thickness direction of the first wall, the projection of the pressure relief groove, the projection of the extended line of the pressure relief groove, the projection of the guide groove and the projection of the extended line of the guide groove jointly enclose the predetermined pressure relief area.

30. The battery cell according to claim 20, characterized in that The guide groove is stamped on the first wall.

31. The battery cell according to claim 1, characterized in that In the thickness direction of the first wall, the first wall is configured to support the electrode assembly.

32. The battery cell according to claim 1, characterized in that The housing comprises: A shell body, wherein a receiving cavity with an opening is formed inside, and the receiving cavity is used to receive the electrode assembly; an end cap for closing the opening; wherein the housing includes the first wall; or The end cover is the first wall.

33. The battery cell according to claim 1, characterized in that: The housing comprises: A shell having a housing formed therein, the housing being used to accommodate the electrode assembly, and openings being formed at opposite ends of the shell, and both openings being in communication with the housing; Two end covers, respectively closing the two openings; Wherein, one of the two end covers is the first wall; or The housing includes the first wall.

34. A battery, characterized in that: Comprising the battery cell according to any one of claims 1-33.

35. The battery according to claim 34, characterized in that The battery further comprises a box body, the battery cell is accommodated in the box body, the box body comprises a bottom plate located at the bottom of the battery cell, and the bottom plate and the first wall are arranged facing each other along the thickness direction of the first wall.

36. An electrical device, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 33 or a battery as claimed in any one of claims 34 to 35, wherein the battery cell is used to provide electrical energy.

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