Battery monomer, battery device and electric device

Abstract

The utility model provides a battery monomer, a battery device and a power utilization device, and belongs to the technical field of batteries. The battery monomer comprises a shell, an electrode assembly and a pressure relief mechanism, the pressure relief mechanism is arranged on the wall part of the shell and comprises a connecting part, a weak part and a pressure relief part, the connecting part is connected with the wall part, the weak part is arranged around the pressure relief part, the weak part is connected with the connecting part and the pressure relief part, the pressure relief part is provided with at least one strip-shaped thinning area, and the minimum thickness of the thinning area is larger than that of the weak part. In a projection plane perpendicular to the thickness direction of the wall part, the orthographic projection of the thinning area does not pass through the geometric center of the orthographic projection of the pressure relief part. The orthographic projection of the thinning area does not pass through the geometric center of the orthographic projection of the pressure relief part, so that the thinning area is far away from the area, with the largest deformation, of the pressure relief part in the using process, the fatigue phenomenon of the thinning area is relieved, and the phenomenon that the detonation position of the pressure relief mechanism appears in the thinning area during pressure relief is relieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery monomer, a battery device and a power utilization device. BACKGROUND

[0002] In recent years, new energy vehicles have made a leap in development. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable important role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also increasing. Among them, the battery device as a core component of new energy vehicles has higher requirements in terms of use reliability and service life.

[0003] In the battery technology, in order to ensure the safety of the battery monomer, a pressure relief mechanism for relieving the internal pressure of the battery monomer is generally provided on the shell of the battery monomer, so that when the internal pressure or temperature of the battery monomer reaches a threshold value, the pressure relief mechanism can be actuated to relieve the internal pressure of the battery monomer. However, the existing battery monomer has a low pressure relief rate when thermal runaway occurs, which causes the battery monomer to be not relieved in time and causes a fire explosion and other risks, thereby resulting in low use reliability of the battery monomer. UTILITY MODEL CONTENT

[0004] The embodiments of the present application provide a battery monomer, a battery device and a power utilization device, which can effectively improve the use reliability of the battery monomer.

[0005] In a first aspect, the embodiments of the present application provide a battery monomer, comprising a shell, an electrode assembly and a pressure relief mechanism; the shell has a wall portion; the electrode assembly is contained in the shell; the pressure relief mechanism is arranged on the wall portion, and the pressure relief mechanism comprises a connecting portion, a weak portion and a pressure relief portion, the connecting portion is connected with the wall portion, the weak portion is arranged around the pressure relief portion, and the weak portion connects the connecting portion and the pressure relief portion, the weak portion is configured to be at least partially destroyed to release the pressure when the pressure inside the shell reaches a threshold value, the pressure relief portion has at least one thinning area, the thinning area is in a strip shape, and the minimum thickness of the thinning area is greater than the minimum thickness of the weak portion; wherein, in the projection plane perpendicular to the thickness direction of the wall portion, the normal projection of the thinning area does not pass through the geometric center of the normal projection of the pressure relief portion.

[0006] In the technical scheme, the wall of the shell is provided with a pressure relief mechanism, the pressure relief mechanism is provided with a weak part, the weak part is configured to be at least partially destroyed to release pressure when the pressure inside the shell reaches a threshold value, and the pressure relief part inside the weak part is formed with a weak area in a strip structure, so as to reduce the structural strength of the pressure relief part, so that the pressure relief part can release stress in the form of deformation during the cyclic change of the internal pressure of the battery monomer, so that the pressure relief mechanism has the function of "breathing", which is beneficial to alleviate the risk of fatigue cracking of the weak part of the pressure relief mechanism during use. Wherein, by setting the minimum thickness of the thinning area to be greater than the minimum thickness of the weak part, and in the projection plane perpendicular to the thickness direction of the wall, by setting the orthographic projection of the thinning area to not pass through the geometric center of the orthographic projection of the pressure relief part, the thinning area can be away from the area where the pressure relief part deforms most during use. It is beneficial to alleviate the fatigue phenomenon of the thinning area, so as to reduce the risk of further weakening the structural strength of the thinning area, so that the phenomenon of the initiation position of the pressure relief mechanism appearing in the thinning area can be alleviated when the battery monomer is in thermal runaway. In turn, it can effectively alleviate the phenomenon of insufficient pressure relief area of the pressure relief mechanism when pressure relief, which is beneficial to reduce the risk of fire and explosion caused by the pressure relief mechanism due to untimely pressure relief, so as to improve the use reliability of the battery monomer.

[0007] In some embodiments, the minimum thickness of the weak part is D1, the minimum thickness of the thinning area is D2, in the projection plane perpendicular to the thickness direction of the wall, the minimum distance between the geometric center of the orthographic projection of the pressure relief part and the orthographic projection of the thinning area is L1, and the maximum distance between the geometric center of the orthographic projection of the pressure relief part and the orthographic projection of the weak part is L2; wherein 0.06mm≤D1≤0.18mm and 0.26mm≤D2≤0.5mm, and 0.1≤L1 / L2≤0.8; or 0.18mm<D1≤0.24mm and 0.35mm≤D2≤0.5mm, and 0.1≤L1 / L2≤0.8; or 0.24mm<D1≤0.3mm and 0.45mm≤D2≤0.5mm, and 0.1≤L1 / L2≤0.8.

[0008] In the technical solution, when 0.06mm≤D1≤0.18mm and 0.26mm≤D2≤0.5mm, or 0.18mm<D1≤0.24mm and 0.35mm≤D2≤0.5mm, or 0.24mm<D1≤0.3mm and 0.45mm≤D2≤0.5mm, by setting the ratio of L1 and L2 to 0.1 to 0.8, the stress release effect of the pressure relief part through deformation in the process of cyclic change of the internal air pressure of the battery cell can be improved, and the distance between the thinnest area and the area with the largest deformation degree of the pressure relief part during use can be adjusted, which can alleviate the fatigue phenomenon of the thinnest area, thereby reducing the risk of weakening the structural strength of the thinnest area, and the phenomenon of the initiation position of the pressure relief mechanism appearing in the thinnest area when the battery cell is in thermal runaway can be alleviated, and the phenomenon of insufficient pressure relief area of the pressure relief mechanism when pressure relief can be alleviated, which can reduce the risk of fire and explosion caused by the pressure relief mechanism not timely pressure relief, and improve the use reliability of the battery cell.

[0009] In some embodiments, 0.2≤L1 / L2≤0.8.

[0010] In the technical solution, when 0.06mm≤D1≤0.18mm and 0.26mm≤D2≤0.5mm, or 0.18mm<D1≤0.24mm and 0.35mm≤D2≤0.5mm, or 0.24mm<D1≤0.3mm and 0.45mm≤D2≤0.5mm, by further setting the ratio of L1 and L2 to 0.2 to 0.8, the stress release effect of the pressure relief part through deformation in the process of cyclic change of the internal air pressure of the battery cell can be improved, and the distance between the thinnest area and the area with the largest deformation degree of the pressure relief part during use can be further adjusted, which can further alleviate the fatigue phenomenon of the thinnest area, thereby further reducing the risk of weakening the structural strength of the thinnest area, and the phenomenon of the initiation position of the pressure relief mechanism appearing in the thinnest area when the battery cell is in thermal runaway can be further alleviated.

[0011] In some embodiments, in the projection plane perpendicular to the thickness direction of the wall part, at least one straight line passing through the geometric center of the normal projection of the pressure relief part does not intersect with the normal projection of the thinnest area.

[0012] In the technical solution, in a projection plane perpendicular to the thickness direction of the wall portion, at least one straight line of the geometric center of the normal projection of the pressure relief portion is arranged to be non-intersected with the normal projection of the thinning area, so that the geometric center of the normal projection of the pressure relief portion is a structure located outside the thinning area. The pressure relief mechanism with this structure can facilitate processing, reduce the difficulty of forming the thinning area, and facilitate the formation of multiple thinning areas on the pressure relief portion. On the other hand, the influence of the area with the largest deformation degree of the pressure relief portion on multiple positions of the thinning area during use can be reduced, thereby effectively alleviating the fatigue phenomenon of the thinning area, further reducing the risk of weakening the structural strength of the thinning area, and further alleviating the phenomenon that the initiation position of the pressure relief mechanism appears in the thinning area when the battery monomer is in thermal runaway.

[0013] In some embodiments, in a projection plane perpendicular to the thickness direction of the wall portion, the normal projection of the thinning area is located on at least one side of the geometric center of the normal projection of the pressure relief portion in a first direction perpendicular to the thickness direction of the wall portion.

[0014] In the technical solution, by arranging the thinning area on at least one side of the geometric center of the pressure relief portion in a first direction, on the one hand, at least one straight line of the geometric center of the normal projection of the pressure relief portion can be arranged to be non-intersected with the normal projection of the thinning area, so that the geometric center of the normal projection of the pressure relief portion is a structure located outside the thinning area. On the other hand, the influence of the area with the largest deformation degree of the pressure relief portion on multiple positions of the thinning area during use can be further reduced, thereby further alleviating the fatigue phenomenon of the thinning area, further reducing the risk of weakening the structural strength of the thinning area, and further alleviating the phenomenon that the initiation position of the pressure relief mechanism appears in the thinning area when the battery monomer is in thermal runaway.

[0015] In some embodiments, both ends of the thinning area in its extension direction are connected to the weak portion.

[0016] In the technical solution, by arranging both ends of the thinning area in its extension direction to be connected to the weak portion, on the one hand, the thinning area and the weak portion can be formed on the pressure relief mechanism, which facilitates the processing of the pressure relief mechanism. On the other hand, the pressure relief portion located inside the weak portion can be divided into multiple areas by the thinning area, which facilitates further improving the effect of the pressure relief portion releasing stress by deformation during the cyclic change of the gas pressure in the battery monomer, and further alleviates the risk of fatigue cracking of the weak portion of the pressure relief mechanism during use.

[0017] In some embodiments, in a projection plane perpendicular to the thickness direction of the wall portion, the normal projection of the thinning area extends along an arc trajectory.

[0018] In the technical scheme, the normal projection of the thinning area in the projection plane perpendicular to the thickness direction of the wall portion is arranged to extend along the arc trajectory, so that the thinning area is a strip-shaped structure extending along the arc trajectory, and the structural strength of the pressure relief portion is low, so that the pressure relief portion can release stress in the form of deformation in the process of cyclic change of the internal gas pressure of the battery monomer, so as to alleviate the risk of fatigue cracking of the weak portion of the pressure relief mechanism in use.

[0019] In some embodiments, the pressure relief portion is provided with two thinning areas, the two thinning areas are oppositely arranged along a first direction, and the geometric center of the normal projection of the pressure relief portion is located between the normal projections of the two thinning areas in the first direction in the projection plane perpendicular to the thickness direction of the wall portion.

[0020] In the technical scheme, by arranging two thinning areas oppositely along the first direction on the pressure relief portion, and arranging the geometric center of the pressure relief portion between the two thinning areas in the first direction, the effect that the pressure relief portion can release stress in the form of deformation in the process of cyclic change of the internal gas pressure of the battery monomer is improved, and the two thinning areas are away from the region of the pressure relief portion with the largest deformation in use, which is beneficial to alleviate the fatigue phenomenon of the thinning area, and thus the phenomenon that the initiation position of the pressure relief mechanism appears in the thinning area when the battery monomer is in thermal runaway is reduced, which is beneficial to reduce the risk of fire and explosion caused by untimely pressure relief of the pressure relief mechanism, and to improve the use reliability of the battery monomer.

[0021] In some embodiments, the weak portion includes two straight line segments and two arc line segments, the two straight line segments are oppositely arranged along a first direction and extend along a second direction, the two arc line segments are oppositely arranged along the second direction and extend along an arc trajectory, one straight line segment, one arc line segment, another straight line segment and another arc line segment are sequentially connected in order, and the first direction, the second direction and the thickness direction of the wall portion are perpendicular to each other; wherein the two ends of the thinning area in its extension direction are connected to the two arc line segments respectively; or, the two ends of the thinning area in its extension direction are connected to the same straight line segment.

[0022] In the technical scheme, the two ends of the thinning area in the extension direction are connected with the two arc segments of the weak part respectively, so that the thinning area can divide the pressure relief part on the inner side of the weak part into multiple areas, and the length of the thinning area can be enlarged, thereby further improving the effect of the pressure relief part releasing stress in the form of deformation in the process of cyclic change of the internal gas pressure of the battery monomer, and further relieving the risk of fatigue cracking of the weak part of the pressure relief mechanism in use. Similarly, the two ends of the thinning area in the extension direction are connected to the same straight segment, on the one hand, the thinning area can divide the pressure relief part on the inner side of the weak part into multiple areas, thereby further improving the effect of the pressure relief part releasing stress in the form of deformation in the process of cyclic change of the internal gas pressure of the battery monomer, and further relieving the risk of fatigue cracking of the weak part of the pressure relief mechanism in use, and on the other hand, the thinning area and the weak part are conveniently formed on the pressure relief mechanism, thereby reducing the processing difficulty of the pressure relief mechanism.

[0023] In some embodiments, the thinning area comprises a plurality of thinning segments connected in sequence; wherein, in a projection plane perpendicular to the thickness direction of the wall part, the orthographic projection of at least one of the thinning segments extends along an arc trajectory, and the orthographic projection of at least one of the thinning segments extends along a straight line trajectory.

[0024] In the technical scheme, the thinning area is provided as a structure comprising a plurality of thinning segments connected in sequence, and in a projection plane perpendicular to the thickness direction of the wall part, the orthographic projection of at least one of the thinning segments is provided as a structure extending along an arc trajectory, and the orthographic projection of at least one of the thinning segments is provided as a structure extending along a straight line trajectory, so as to facilitate the formation of a thinning area with a strip structure of different shapes, thereby being suitable for pressure relief mechanisms of different structures.

[0025] In some embodiments, the thinning area comprises three thinning segments; wherein, in a projection plane perpendicular to the thickness direction of the wall part, the orthographic projection of the thinning segment in the middle of the three thinning segments extends along an arc trajectory, and the orthographic projection of the thinning segments at both ends of the three thinning segments extends along a straight line trajectory.

[0026] In the technical scheme, the thinning segments of the thinning area are provided as three, and in a projection plane perpendicular to the thickness direction of the wall part, the orthographic projection of the thinning segment in the middle of the three thinning segments is provided as a structure extending along an arc trajectory, and the orthographic projection of the thinning segments at both ends of the three thinning segments is provided as a structure extending along a straight line trajectory, thereby improving the regularity of the shape of the thinning area, and reducing the difficulty of forming the thinning, so as to reduce the processing difficulty of the pressure relief mechanism.

[0027] In some embodiments, the thinning region comprises a plurality of thinning segments connected in sequence; wherein, in a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of the thinning segments extends along a straight line trajectory, and the extending directions of the orthographic projections of two adjacent thinning segments intersect.

[0028] In the above technical solution, by setting the thinning region to comprise a plurality of thinning segments connected in sequence, in a projection plane perpendicular to the thickness direction of the wall portion, the thinning segments are structures extending along a straight line trajectory, and the extending directions of the orthographic projections of each adjacent two thinning segments are intersecting structures, to form a thinning region in the shape of a broken line, which is beneficial for being suitable for pressure relief mechanisms of different structures.

[0029] In some embodiments, the thinning segments of the thinning region are two.

[0030] In the above technical solution, by setting the thinning segments of the thinning region to be two, the two thinning segments are connected and the extending directions thereof are intersecting structures, to form a thinning region in the shape of a "V" structure, which is simple in structure and easy to manufacture, and is beneficial for reducing the manufacturing difficulty of the pressure relief mechanism.

[0031] In some embodiments, in a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of the thinning region extends along a straight line trajectory.

[0032] In the above technical solution, by setting the extending direction of the orthographic projection of the thinning region in a projection plane perpendicular to the thickness direction of the wall portion to be a structure extending along a straight line trajectory, it is beneficial for facilitating the forming of the thinning region on the pressure relief portion, and for reducing the processing difficulty of the pressure relief mechanism.

[0033] In some embodiments, in a projection plane perpendicular to the thickness direction of the wall portion, the position of the orthographic projection of the thinning region closest to the geometric center of the orthographic projection of the pressure relief portion is a first position, and the position of the orthographic projection of the thinning region farthest from the geometric center of the orthographic projection of the pressure relief portion is a second position; wherein, the minimum thickness of the thinning region at the first position is greater than the minimum thickness of the thinning region at the second position.

[0034] In the technical solution, the minimum thickness of the first position of the thinned area closest to the center area of the pressure relief part is set to be greater than the minimum thickness of the second position of the thinned area farthest from the center area of the pressure relief part, so that the structural strength of the first position of the thinned area closest to the center area of the pressure relief part is greater, thereby increasing the structural strength of the position of the thinned area closest to the pressure relief part where the deformation amount is the largest during use, so that the phenomenon of cracking of the first position of the thinned area closest to the center area of the pressure relief part during thermal runaway of the battery cell is alleviated while the pressure relief mechanism is able to release stress through deformation to reduce the risk of early cracking of the weak part, further alleviating the phenomenon of the initiation position of the pressure relief mechanism appearing in the thinned area, thereby further alleviating the phenomenon of insufficient pressure relief area of the pressure relief mechanism during pressure relief, which is beneficial to further reducing the risk of fire and explosion caused by the pressure relief mechanism due to untimely pressure relief, and further improving the use reliability of the battery cell.

[0035] In some embodiments, the minimum thickness of the thinned area in the cross section gradually increases from the second position to the first position along the extension direction of the thinned area.

[0036] In the technical solution, the minimum thickness of the thinned area in the cross section gradually increases from the second position to the first position along the extension direction of the thinned area, which on the one hand facilitates the formation of thinned areas with different thicknesses to achieve a structure in which the structural strength of the thinned area is greater the closer it is to the center area of the pressure relief part, and on the other hand reduces the difficulty of forming the thinned area to reduce the manufacturing difficulty of the pressure relief mechanism, thereby further alleviating the phenomenon that the closer the thinned area is to the center area of the pressure relief part, the more likely it is to crack during thermal runaway of the battery cell, thereby further reducing the risk of the initiation position of the pressure relief mechanism appearing in the thinned area.

[0037] In some embodiments, the thinned area is connected to the weak part at both ends in the extension direction thereof, the thinned area comprises two first segments connected to each other, the connection position of the two first segments is the first position, and the position where the first segment is connected to the weak part is the second position; wherein the lengths of the two first segments are equal along the extension direction of the thinned area.

[0038] In the technical solution, the two first sections formed by the first position as a boundary of the thinning area are set as structures with equal lengths, and the other ends of the two first sections are connected with the weak part, so that on the one hand, the shape regularity of the thinning area can be improved, and the processing difficulty of the thinning area can be reduced, and on the other hand, the effect that the pressure relief part can release stress by deformation in the process of the cyclic change of the internal gas pressure of the battery monomer can be further improved.

[0039] In some embodiments, the weak part includes a first weak section and a second weak section connected in sequence, and the minimum thickness of the second weak section is greater than the minimum thickness of the first weak section.

[0040] In the technical solution, the minimum thickness of the second weak section of the weak part is set to be greater than the minimum thickness of the first weak section of the weak part, so that the structural strength of the second weak section is greater than that of the first weak section, and when the battery monomer is pressure released, the first weak section can be preferentially cracked compared with the second weak section, so that the pressure relief part is flipped around the second weak section and opens the pressure relief, which is beneficial to improve the pressure relief smoothness of the pressure relief mechanism of the battery monomer, so as to improve the pressure relief timeliness of the battery monomer.

[0041] In some embodiments, the weak part includes two straight sections and two arc sections, the two straight sections are oppositely arranged along a first direction and extend along a second direction, the two arc sections are oppositely arranged along the second direction and extend along an arc track, one straight section, one arc section, another straight section and another arc section are connected in sequence, the first direction, the second direction and the thickness direction of the wall part are perpendicular to each other; wherein the first weak section includes two arc sections and one straight section, and the second weak section is another straight section.

[0042] In the technical solution, the first weak section includes two arc sections and one straight section, the second weak section is another straight section of the weak part, and one arc section, one straight section, another arc section and another straight section are connected in sequence, by setting the two arc sections as structures extending along the arc track and oppositely arranged along the second direction, and setting the two straight sections as structures extending along the second direction and oppositely arranged along the first direction, the battery monomer with this structure can on the one hand facilitate the forming of the first weak section and the second weak section with different thicknesses on the pressure relief mechanism, which is beneficial to reduce the processing difficulty of the pressure relief mechanism, and on the other hand, the smoothness of the pressure relief part flipping around the second weak section after the first weak section is cracked can be further improved, and the flipping angle of the pressure relief part inside the weak part of the pressure relief mechanism can be further expanded, so as to further improve the pressure relief smoothness and the pressure relief rate of the battery monomer.

[0043] In some embodiments, the minimum thickness of the weakened portion is D1, the minimum thickness of the thinned region is D2, and 0.18≤D1 / D2≤0.62 is satisfied.

[0044] In the above technical solution, by setting the minimum thickness of the weakened portion to be 0.18 to 0.62 times the minimum thickness of the thinned region, on the one hand, the minimum thickness of the weakened portion is set to be greater than or equal to 0.18 times the minimum thickness of the thinned region, so as to alleviate the risk of early cracking caused by the minimum thickness of the weakened portion being too small, and to improve the use reliability of the battery monomer; on the other hand, the minimum thickness of the weakened portion is set to be less than or equal to 0.62 times the minimum thickness of the thinned region, so as to reduce the risk of the thinned region cracking before the weakened portion when the battery monomer is pressure released, so as to further alleviate the phenomenon that the detonation position of the pressure relief mechanism is in the thinned region when the battery monomer is in thermal runaway, thereby further alleviating the phenomenon that the pressure relief area of the pressure relief mechanism is insufficient when the pressure relief mechanism is pressure released, which is conducive to further reducing the risk of fire and explosion caused by the pressure relief mechanism not being timely pressure released, and thus the use reliability of the battery monomer is further improved.

[0045] In some embodiments, 0.02mm≤D1≤0.24mm; and / or, 0.22mm≤D2≤0.38mm.

[0046] In the above technical solution, by setting the minimum thickness of the weakened portion to be 0.02mm to 0.24mm, on the one hand, the minimum thickness of the weakened portion is set to be greater than or equal to 0.02mm, so as to alleviate the risk of early cracking caused by the minimum thickness of the weakened portion being too small, and to improve the reliability of the battery monomer; on the other hand, the minimum thickness of the weakened portion is set to be less than or equal to 0.24mm, so as to reduce the burst pressure required by the pressure relief mechanism when the pressure relief mechanism is pressure released, so as to reduce the risk of explosion or explosion of the battery monomer when the battery monomer is in thermal runaway. Similarly, by setting the minimum thickness of the thinned region to be 0.22mm to 0.38mm, on the one hand, the minimum thickness of the thinned region is set to be greater than or equal to 0.22mm, so as to improve the structural strength of the thinned region, so as to alleviate the phenomenon that the thinned region cracks before the weakened portion when the battery monomer is pressure released, so as to further alleviate the phenomenon that the detonation position of the pressure relief mechanism is in the thinned region when the battery monomer is in thermal runaway; on the other hand, the minimum thickness of the thinned region is set to be less than or equal to 0.38mm, so as to improve the weakening effect of the structural strength of the pressure relief portion, so as to facilitate the pressure relief portion to release stress through deformation during the cyclic change of the internal pressure of the battery monomer, thereby further improving the "breathing" effect of the pressure relief mechanism during use.

[0047] In some embodiments, at least part of the pressure relief portion is raised in a direction towards or away from the electrode assembly along a thickness direction of the wall portion and forms a raised portion, and the weak portion is arranged outside the raised portion.

[0048] In the above technical solution, by arranging the raised portion raised in a direction towards or away from the electrode assembly on the pressure relief portion inside the weak portion, and arranging the weak portion outside the raised portion, on one hand, the difficulty of processing the weak portion on the pressure relief mechanism can be reduced, and the material flow form of the weak portion during processing can be improved to improve the processing consistency of the weak portion; on the other hand, the raised portion inside the weak portion forms a pre-deformation structure, so that the weak portion of the pressure relief mechanism can crack and release pressure when the battery monomer is in thermal runaway, thereby increasing the thickness of the weak portion under the same burst pressure to alleviate the fatigue cracking of the weak portion during use, thereby effectively reducing the risk of early valve opening of the pressure relief mechanism to improve the service life and use reliability of the battery monomer.

[0049] In some embodiments, the raised portion includes at least part of the thinned area.

[0050] In the above technical solution, by arranging the raised portion to include at least part of the thinned area, so that the thinned area is also at least partially raised, the pressure relief portion can further release stress by deformation during the cyclic change of the internal gas pressure of the battery monomer, thereby further improving the “breathing” effect of the pressure relief mechanism during use.

[0051] In some embodiments, along the thickness direction of the wall portion, the pressure relief mechanism has opposite first and second surfaces, the first surface is provided with a groove, the groove bottom wall includes the weak portion, and part of the groove bottom wall is raised in a direction from the second surface to the first surface and forms the raised portion.

[0052] In the above technical solution, by arranging the groove on the first surface of the pressure relief mechanism, and arranging the raised portion raised in a direction from the second surface to the first surface, the battery monomer with this structure can realize that the raised portion is raised on the side facing the groove, on one hand, the groove and the raised portion can share part of the space in the thickness direction of the wall portion, which is beneficial to save the space occupied by the pressure relief mechanism to improve the space utilization of the battery monomer, on the other hand, the groove can also protect the raised portion to some extent to reduce the wear or impact of the raised portion during use or assembly.

[0053] In some embodiments, along the thickness direction of the wall portion, the second surface is arranged to face the electrode assembly.

[0054] In the technical solution, the second surface of the pressure relief mechanism is arranged to face the electrode assembly, and the protruding portion is arranged to protrude in a direction away from the electrode assembly in the thickness direction of the wall portion. On the one hand, the protruding portion can reduce the occupation of the internal space of the battery monomer, improve the space for accommodating the electrode assembly in the battery monomer, and improve the energy density of the battery monomer. On the other hand, the protruding portion can reduce the interference between the protruding portion and other components in the battery monomer, and improve the use reliability of the battery monomer.

[0055] In some embodiments, the pressure relief mechanism is provided with a pressure relief groove and forms the weak portion. In a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of the weak portion and the orthographic projection of the groove wall surface of the pressure relief groove overlap. The pressure relief groove is arranged on the groove bottom surface of the groove.

[0056] In the technical solution, the pressure relief groove is arranged on the pressure relief mechanism to form the weak portion, so as to reduce the difficulty of forming the weak portion on the pressure relief mechanism. The pressure relief groove is arranged on the groove bottom surface of the groove, so that the pressure relief groove and the groove are located on the same side of the wall portion in the thickness direction. Therefore, the pressure relief groove can be machined synchronously with the groove, so as to reduce the difficulty of forming the pressure relief groove on the pressure relief mechanism, and optimize the production rhythm of the battery monomer.

[0057] In some embodiments, the pressure relief mechanism is provided with a pressure relief groove and forms the weak portion. In a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of the weak portion and the orthographic projection of the groove wall surface of the pressure relief groove overlap.

[0058] In the technical solution, the pressure relief groove is arranged on the pressure relief mechanism to form the weak portion, so as to reduce the difficulty of forming the weak portion on the pressure relief mechanism. The pressure relief groove is arranged on the groove bottom surface of the groove, so that the pressure relief groove and the groove are located on the same side of the wall portion in the thickness direction. Therefore, the pressure relief groove can be machined synchronously with the groove, so as to reduce the difficulty of forming the pressure relief groove on the pressure relief mechanism, and optimize the production rhythm of the battery monomer.

[0059] In some embodiments, the pressure relief portion is provided with a thinning groove and forms the thinning area. In a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of the thinning area and the orthographic projection of the groove wall surface of the thinning groove overlap.

[0060] In the technical solution, the thinning groove is arranged on the pressure relief portion to form the thinning area, so as to reduce the difficulty of forming the thinning area on the pressure relief portion. The structure is simple and easy to manufacture.

[0061] In some embodiments, the pressure relief mechanism is arranged separately from the wall portion, or the pressure relief mechanism is formed integrally with the wall portion.

[0062] In the technical solution, the pressure relief mechanism and the wall part are arranged in a split structure, so that the weak part and the thinning area are formed on the pressure relief mechanism first, and then the pressure relief mechanism is assembled to the wall part of the shell, which is beneficial to reduce the forming difficulty of the pressure relief mechanism and optimize the production rhythm of the battery cell. The pressure relief mechanism and the wall part are integrally formed, i.e., the pressure relief mechanism and the wall part are in an integrated structure. The battery cell with the structure is beneficial to improve the structural strength of the pressure relief mechanism connected to the wall part, so as to reduce the risk of falling of the pressure relief mechanism in use, thereby improving the use stability and reliability of the battery cell.

[0063] In some embodiments, the shell includes a shell body and an end cover; the shell body includes an integrally formed side wall and a bottom 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 of the side wall is closed to form an opening along the thickness direction of the wall part, the side wall and the bottom wall jointly define a receiving cavity, and the electrode assembly is received in the receiving cavity; the end cover closes the opening; wherein the end cover is the wall part; or the bottom wall is the wall part.

[0064] In the technical solution, the wall part of the shell is arranged as an end cover for closing the opening of the shell. The battery cell with the structure facilitates the arrangement of the pressure relief mechanism on the end cover, thereby reducing the manufacturing difficulty of the battery cell and improving the production efficiency of the battery cell. The wall part of the shell is arranged as a bottom wall opposite to the end cover in the thickness direction of the wall part. The battery cell with the structure can realize that the area of the shell provided with the pressure relief mechanism is away from the end cover, thereby effectively relieving the stress generated by the mutual connection of the end cover and the shell on the pressure relief mechanism, reducing the impact on the pressure relief mechanism, and further reducing the risk of cracking or structural strength reduction of the weak part of the pressure relief mechanism under the pulling action of the stress, thereby improving the service life and use reliability of the battery cell.

[0065] In a second aspect, the embodiments of the present application also provide a battery device including the battery cell.

[0066] In a third aspect, the embodiments of the present application also provide a power utilization device including the battery cell, and the battery cell is used to provide electric energy. BRIEF DESCRIPTION OF DRAWINGS

[0067] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0068] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0069] Figure 2 Exploded views of the structure of the battery device provided in some embodiments of this application;

[0070] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0071] Figure 4 Exploded views of the structure of a single battery cell provided in some embodiments of this application;

[0072] Figure 5 A front view of the pressure relief mechanism provided in some embodiments of this application in the thickness direction of the wall portion;

[0073] Figure 6 Cross-sectional views of pressure relief mechanisms provided in some embodiments of this application;

[0074] Figure 7 for Figure 6 A partial enlarged view of point A of the pressure relief mechanism shown;

[0075] Figure 8 for Figure 6 A partial enlarged view of point B of the pressure relief mechanism shown;

[0076] Figure 9 A front view of the pressure relief mechanism provided in some embodiments of this application in the thickness direction of the wall portion;

[0077] Figure 10 A front view of the pressure relief mechanism provided in some embodiments of this application in the thickness direction of the wall portion.

[0078] Icons: 1000 - Vehicle; 100 - Battery assembly; 10 - Housing; 11 - First housing body; 12 - Second housing body; 20 - Battery cell; 21 - Casing; 211 - Wall; 212 - Housing; 2121 - Opening; 213 - End cap; 22 - Electrode assembly; 221 - Tab; 23 - Pressure relief mechanism; 231 - Connection; 232 - Weak section; 232a - First weak section; 232b - Second weak section; 2321 - Straight section; 2322 - Arc segment; 233-Pressure relief section; 2331-Thinning area; 2331a-Thinning section; 2331b-First position; 2331c-Second position; 2331d-First segment; 2332-Thinning groove; 2333-Raised section; 234-Pressure relief groove; 235-First surface; 2351-Groove; 236-Second surface; 24-Electrode terminal; 200-Controller; 300-Motor; X-Thickness direction of the wall; Y-First direction; Z-Second direction. Detailed Implementation

[0079] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0080] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as those commonly understood by one of ordinary skill in the art to which this application belongs; the terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, not to describe a particular order or primary and secondary relationship.

[0081] In the present application, the phrase "embodiments" means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily all refer to the same embodiments, nor is it necessarily independent or alternative embodiments to each other.

[0082] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium; can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0083] In the present application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the associated objects before and after it.

[0084] In the embodiments of the present application, the same reference signs 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, and the overall thickness, length, width, and other dimensions of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0085] “Multiple” appearing in the present application means two or more (including two).

[0086] In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging.

[0087] 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-acid battery, etc., which is not limited in the embodiments of the present application.

[0088] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the battery cell, active ions (such as lithium ions) are inserted and extracted between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, which can prevent the positive and negative electrodes from short-circuiting to some extent, and at the same time, the active ions can pass through.

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

[0090] As an example, the positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode active material is arranged on any one or both of the two opposite surfaces of the positive electrode current collector.

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

[0092] As an example, the positive active material can include at least one of a lithium-containing phosphate, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive active material can also be used. These positive active materials can be used alone only one or two or more can be used in combination. Among them, examples of the lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (which can also be referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxide can include, but are not limited to, at least one of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2), and modified compounds thereof.

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

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

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

[0096] As an example, the negative electrode sheet can include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

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

[0098] As an example, the negative active material can employ a negative active material for a battery cell known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative active material can also be used. These negative active materials can be used alone only one or in combination of two or more.

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

[0100] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0101] In some embodiments, the separator is a separator film. The separator film can be various, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

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

[0103] In some embodiments, the separator is a solid-state electrolyte. The solid-state electrolyte is disposed between the positive and negative electrodes and functions to transport ions and separate the positive and negative electrodes.

[0104] In some embodiments, the battery cell further includes an electrolyte that functions to conduct ions between the positive and negative electrodes. The electrolyte can be in a liquid, gel, or solid state. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[0105] In some embodiments, the electrolyte salt can include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoroboric oxalate, lithium bisoxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorodioxalate phosphate.

[0106] In some embodiments, the solvent can include at least one of ethylene carbonate, propylene carbonate, methyl ethyl 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, butanediol sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be an ether solvent. The ether solvent can 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, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0107] Among them, the gel electrolyte includes a polymer as a skeleton network of the electrolyte, in combination with an ionic liquid-lithium salt.

[0108] Among them, the solid-state electrolyte includes a polymer solid-state electrolyte, an inorganic solid-state electrolyte, and a composite solid-state electrolyte.

[0109] As an example, the polymer solid-state electrolyte can be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single-ion polymer, a polyionic liquid-lithium salt, cellulose, etc.

[0110] As an example, the inorganic solid-state electrolyte can include one or more of an oxide solid-state electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON thin film), a sulfide solid-state electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorous sulfide, argyrodite), amorphous sulfide), and a halide solid-state electrolyte, a nitride solid-state electrolyte, and a hydride solid-state electrolyte.

[0111] As an example, the composite solid-state electrolyte is formed by adding an inorganic solid-state electrolyte filler to a polymer solid-state electrolyte.

[0112] In some embodiments, the electrode assembly is in a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound into the jelly-roll structure.

[0113] In some embodiments, the electrode assembly is in a stacked structure.

[0114] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be provided, respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets are alternately stacked.

[0115] As an example, a plurality of positive electrode sheets can be provided, and the negative electrode sheet is folded to form a plurality of folded segments that are stacked. One positive electrode sheet is clamped between adjacent folded segments.

[0116] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded segments that are stacked.

[0117] As an example, a plurality of separators can be provided, respectively, between any adjacent positive electrode sheets or negative electrode sheets.

[0118] As an example, the separators can be continuously provided and arranged between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0119] In some embodiments, the electrode assembly can have a shape of a cylinder, a flat shape, or a multi-prism shape, etc.

[0120] In some embodiments, the electrode assembly can be provided with tabs. The tabs can guide current out of the electrode assembly. The tabs include positive tabs and negative tabs.

[0121] In some embodiments, the battery cell can include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film, etc.

[0122] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. The prismatic battery cell includes, but is not limited to, a square battery cell, a blade-shaped battery cell, a multi-prismatic battery cell, such as a hexagonal prismatic battery cell, etc.

[0123] The battery device mentioned in the embodiments of the present application can include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can include a plurality of battery cells connected in series, in parallel, or in a mixed connection through a busbar component.

[0124] In some embodiments, the battery cell assembly is generally formed by arranging a plurality of battery cells; as an example, the battery cell assembly can be a battery module formed by arranging and fixing a plurality of battery cells into an independent module. As an example, the battery module can be formed by bundling a plurality of battery cells with a cable tie.

[0125] In some embodiments, the battery device can be a battery pack including a box body and one or more battery cell assemblies accommodated in the box body.

[0126] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be accommodated in the box body by fixing the battery module in the box body.

[0127] As an example, the battery cell assembly can also be accommodated in the box body by directly fixing a plurality of battery cells in the box body.

[0128] As an example, the box body can include a first box body and a second box body. The first box body and the second box body are buckled so that a closed space is formed inside the box body to accommodate the battery cell assembly. Here, closed means covered or closed, which can be sealed or unsealed. The first box body can be a top cover or a bottom plate.

[0129] As an example, the box body can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are connected with the frame, respectively, so that a closed space is formed inside the box body to accommodate the battery cell assembly.

[0130] As an example, the box body can be part of the chassis structure of a vehicle. For example, the top cover of the box body can be at least part of the floor of the vehicle, or the frame of the box body can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0131] In some embodiments, the battery device refers to an energy storage device, which includes a box body provided with a door on at least one side. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0132] The battery device has the outstanding advantages of high energy density, small environmental pollution, large power density, long service life, wide adaptation range, and small self-discharge coefficient, and is an important part of the development of new energy today. The development of battery technology needs to consider many design factors, such as energy density, cycle life, discharge capacity, and charge-discharge rate. In addition, the reliability of the battery device also needs to be considered.

[0133] In order to ensure the safety of the battery cell, a pressure relief mechanism is usually arranged on the shell of the battery cell to release the internal pressure of the battery cell, thereby effectively improving the safety of the battery cell. The pressure relief mechanism is usually in a flat plate structure, and a pressure relief groove in an annular structure is punched on the pressure relief mechanism, so that the pressure relief mechanism can be cracked along the area where the pressure relief groove is located to release the internal pressure of the battery cell. During the charging and discharging process of the battery cell, the internal pressure of the battery cell changes cyclically, causing the shell of the battery cell to expand and contract normally during use. Therefore, in the related art, in order to make the pressure relief mechanism also have the function of "breathing" to alleviate the fatigue cracking of the pressure relief mechanism during the cyclic change of the internal pressure of the battery cell, a thinning groove is usually arranged in the area inside the pressure relief groove of the pressure relief mechanism, and the two ends of the thinning groove in the extension direction are connected with the pressure relief groove, so as to reduce the structural strength of the area inside the pressure relief groove of the pressure relief mechanism, so that the area inside the pressure relief groove of the pressure relief mechanism can release stress by deformation during the cyclic change of the internal pressure of the battery cell, so that the pressure relief mechanism also has the function of "breathing", thereby effectively alleviating the risk of fatigue cracking of the area of the pressure relief mechanism provided with the pressure relief groove during use. However, the battery cell with such structure is prone to crack along the area where the thinning groove is located rather than along the area where the pressure relief groove is located when thermal runaway occurs, especially in the structure where the thinning groove is relatively close to the center of the area inside the pressure relief groove of the pressure relief mechanism. Because the center of the area inside the pressure relief groove of the pressure relief mechanism has the largest deformation amount during use, it is more likely to crack along the area where the thinning groove is located rather than along the area where the pressure relief groove is located, resulting in a smaller area of the pressure relief mechanism being opened for pressure relief, so that the pressure relief area of the battery cell is insufficient when thermal runaway occurs, thereby causing a lower pressure relief rate of the battery cell when thermal runaway occurs, which leads to the risk of fire explosion or connection failure caused by the battery cell not being relieved in time, which is not conducive to improving the use reliability of the battery cell.

[0134] In view of the above, in order to solve the problem of low use reliability of the battery monomer, the application provides a battery monomer, which comprises a shell, an electrode assembly and a pressure relief mechanism. The shell has a wall portion. The electrode assembly is accommodated in the shell. The pressure relief mechanism is arranged on the wall portion and comprises a connecting portion, a weak portion and a pressure relief portion. The connecting portion is connected to the wall portion. The weak portion is arranged around the pressure relief portion and connects the connecting portion and the pressure relief portion. The weak portion is configured to be at least partially destroyed to release pressure when the pressure inside the shell reaches a threshold value. The pressure relief portion has at least one thinned area. The thinned area is in a strip shape. The minimum thickness of the thinned area is greater than the minimum thickness of the weak portion. In a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of the thinned area does not pass through the geometric center of the orthographic projection of the pressure relief portion.

[0135] In the battery monomer with the above structure, the pressure relief mechanism is arranged on the wall portion of the shell. The pressure relief mechanism is provided with a weak portion configured to be at least partially destroyed to release pressure when the pressure inside the shell reaches a threshold value. The pressure relief portion inside the weak portion is formed with a thinned area in a strip shape, thereby reducing the structural strength of the pressure relief portion, so that the pressure relief portion can release stress by deformation during the cyclic change of the internal pressure of the battery monomer, so that the pressure relief mechanism has a "breathing" effect, which is beneficial to alleviate the risk of fatigue cracking of the weak portion of the pressure relief mechanism during use. By setting the minimum thickness of the thinned area to be greater than the minimum thickness of the weak portion, and by setting the orthographic projection of the thinned area not to pass through the geometric center of the orthographic projection of the pressure relief portion in the projection plane perpendicular to the thickness direction of the wall portion, the thinned area can be away from the area of the pressure relief portion with the largest deformation degree during use, which is beneficial to alleviate the fatigue phenomenon of the thinned area, thereby reducing the risk of further weakening the structural strength of the thinned area, so that the phenomenon of the initiation position of the pressure relief mechanism appearing in the thinned area can be alleviated when the battery monomer is in thermal runaway, and the phenomenon of insufficient pressure relief area of the pressure relief mechanism during pressure relief can be effectively alleviated, which is beneficial to reduce the risk of fire and explosion caused by untimely pressure relief of the pressure relief mechanism, thereby improving the use reliability of the battery monomer.

[0136] The battery monomer disclosed in the application can be used in an electric device such as a vehicle, a ship or an aircraft, etc. The power supply system of the electric device can be composed of the battery monomer and the battery device disclosed in the application, which is beneficial to alleviate the problem of fire and explosion caused by untimely pressure relief of the battery monomer, thereby improving the use reliability of the battery monomer.

[0137] The embodiments of the present application provide a power consumption device using a battery monomer or a battery device as a power supply. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft and the like. The electric toy can include a fixed or mobile electric toy, such as a game machine, an electric automobile toy, an electric ship toy and an electric aircraft toy and the like. The spacecraft can include an airplane, a rocket, a space shuttle and a spacecraft and the like.

[0138] The following embodiments are described by taking a power consumption device as a vehicle in an embodiment of the present application as an example for convenience of description.

[0139] Please refer to Figure 1 , Figure 1 A structural schematic diagram of a vehicle 1000 provided by some embodiments of the present application is shown in FIG. 1. The vehicle 1000 can be a fuel automobile, a gas automobile or a new energy automobile. The new energy automobile can be a pure electric automobile, a hybrid electric automobile or a range extended automobile and the like. The vehicle 1000 is internally provided with a battery device 100. The battery device 100 can be arranged at the bottom of the vehicle 1000, or arranged at the head of the vehicle 1000, or arranged at the tail of the vehicle 1000. The battery device 100 can be used to supply power for the vehicle 1000, for example, the battery device 100 can be used as an operating power supply or a use power supply of the vehicle 1000. The vehicle 1000 can further include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power for the motor 300, for example, to meet the power consumption demand of the vehicle 1000 during starting, navigation and driving.

[0140] In some embodiments of the present application, the battery device 100 can not only be used as an operating power supply or a use power supply of the vehicle 1000, but also be used as a driving power supply of the vehicle 1000, instead of or partially instead of fuel or natural gas to provide driving power for the vehicle 1000.

[0141] Please refer to Figure 2 and Figure 3 , Figure 2 A structural explosion diagram of the battery device 100 provided by some embodiments of the present application is shown in FIG. 2. Figure 3 A structural schematic diagram of a battery monomer 20 provided by some embodiments of the present application is shown in FIG. 3. The battery device 100 includes a box body 10 and the battery monomer 20. The battery monomer 20 is used to be accommodated in the box body 10.

[0142] The box 10 is configured to provide an assembling space for the battery cell 20. The box 10 can have various structures. In some embodiments, the box 10 can include a first box body 11 and a second box body 12. The first box body 11 and the second box body 12 are coupled to each other, and the first box body 11 and the second box body 12 together define an assembling space for accommodating the battery cell 20. The second box body 12 can be a hollow structure with one end open, and the first box body 11 can be a plate structure. The first box body 11 is coupled to the open end of the second box body 12, so that the first box body 11 and the second box body 12 together define the assembling space. Alternatively, the first box body 11 and the second box body 12 can both be hollow structures with one side open. The open side of the first box body 11 is coupled to the open side of the second box body 12.

[0143] Of course, the box 10 formed by the first box body 11 and the second box body 12 can have various shapes, such as a cylinder, a cuboid, or a square, etc. For example, in some embodiments, the box 10 has a cuboid shape. Figure 2

[0144] In the battery device 100, the battery cell 20 disposed in the box 10 can be one or multiple. When the battery cell 20 disposed in the box 10 is multiple, the multiple battery cells 20 can be connected in series, in parallel, or in a mixed connection. The mixed connection means that the multiple battery cells 20 are connected in series and in parallel. The multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed connection, and then the multiple battery cells 20 are accommodated in the box 10. Alternatively, the multiple battery cells 20 can be first connected in series, in parallel, or in a mixed connection to form a battery module, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and the whole is accommodated in the box 10.

[0145] In some embodiments, the battery device 100 can further include other structures. For example, the battery device 100 can further include a current collecting component configured to connect the multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0146] Each battery cell 20 can be a secondary battery or a primary battery, and can be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can have a cuboid, a cylinder, a prism, or other shapes, etc. For example, in some embodiments, the battery cell 20 has a cuboid shape. Figure 3

[0147] According to some embodiments of the present application, reference is made to Figure 3 , and further reference is made to Figure 4 , Figure 5 , Figure 6 , Figure 7 , and Figure 8 ​​, Figure 4 This is an exploded view of the structure of a battery cell 20 provided in some embodiments of this application. Figure 5 This is a front view of the pressure relief mechanism 23 provided in some embodiments of this application in the thickness direction X of the wall portion. Figure 6 This is a cross-sectional view of the pressure relief mechanism 23 provided in some embodiments of this application. Figure 7 for Figure 6 A partial enlarged view of point A of the pressure relief mechanism 23 shown. Figure 8 for Figure 6 The diagram shows a partial enlarged view of the pressure relief mechanism 23 at point B. This application provides a battery cell 20, which includes a housing 21, an electrode assembly 22, and a pressure relief mechanism 23. The housing 21 has a wall portion 211. The electrode assembly 22 is housed within the housing 21. The pressure relief mechanism 23 is disposed on the wall portion 211 and includes a connecting portion 231, a weak portion 232, and a pressure relief portion 233. The connecting portion 231 is connected to the wall portion 211. The weak portion 232 surrounds the pressure relief portion 233 and connects the connecting portion 231 and the pressure relief portion 233. The weak portion 232 is configured to be at least partially destroyed to release pressure when the pressure inside the housing 21 reaches a threshold. The pressure relief portion 233 has at least one thinning region 2331, which is strip-shaped, and the minimum thickness of the thinning region 2331 is greater than the minimum thickness of the weak portion 232. In the projection plane perpendicular to the thickness direction X of the wall, the orthographic projection of the thinning region 2331 does not pass through the geometric center of the orthographic projection of the pressure relief section 233.

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

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

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

[0151] It should be noted that the wall portion 211 provided with the pressure relief mechanism 23 can be an end cover 213 of the shell 21, or can be one of the bottom wall of the shell 212 or the plurality of walls of the side wall of the shell 212. Exemplarily, in Figure 3 and Figure 4 , the wall portion 211 is the end cover 213 of the shell 21, of course, in other embodiments, the wall portion 211 can also be the bottom wall of the shell 212, and the pressure relief mechanism 23 is arranged on one wall of the shell 212 opposite the end cover 213 in the thickness direction X of the wall portion, and the wall portion 211 can also be the side wall of the shell 212.

[0152] When assembling the battery cell 20, the electrode assembly 22 can be first placed in the shell 212, and the electrolyte is filled into the shell 212, and then the end cover 213 is covered on the opening 2121 of the shell 212 to complete the assembly of the battery cell 20.

[0153] The shell 212 can be of various shapes, such as a cylindrical body, a cuboid or a prismatic structure, etc. The shape of the shell 212 can be determined according to the specific shape of the electrode assembly 22. For example, if the electrode assembly 22 is a cylindrical structure, a cylindrical shell 212 can be selected; if the electrode assembly 22 is a cuboid structure, a cuboid shell 212 can be selected. Of course, the structure of the end cover 213 can also be various, such as a plate structure or a hollow structure with one end open, etc.

[0154] Of course, it is understandable that the shell 21 is not limited to the above structure, and the shell 21 can also be of other structures, for example, the shell 21 can include a shell 212 and two end covers 213, the shell 212 is a hollow structure with openings 2121 on opposite sides, one end cover 213 is covered on one opening 2121 of the shell 212 and forms a sealed connection to form a sealed space for accommodating the electrode assembly 22 and the electrolyte, that is, the shell 212 is formed with openings 2121 on opposite sides, and the two end covers 213 are respectively covered on the two sides of the shell 212 to close the corresponding openings 2121.

[0155] Optionally, the structure of the electrode assembly 22 can be various, such as the electrode assembly 22 can be a winding structure formed by winding the positive electrode sheet, the separator and the negative electrode sheet, or can be a laminated structure formed by laminating the positive electrode sheet, the separator and the negative electrode sheet.

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

[0157] Optionally, the electrode assembly 22 accommodated in the shell 21 can be one or more. Exemplarily, inFigure 4 In this embodiment, only one electrode assembly 22 is provided inside the outer casing 21 of the battery cell 20. Of course, in other embodiments, there may be multiple electrode assemblies 22 provided inside the outer casing 21 of the battery cell 20. Multiple electrode assemblies 22 are stacked along their thickness direction. That is, multiple electrode assemblies 22 are stacked along the thickness direction of the battery cell 20. For example, there may be two, three, four, five, six, seven or eight electrode assemblies 22 housed in the outer casing 21.

[0158] In some embodiments, see Figure 3 and Figure 4 As shown, the battery cell 20 may also include an electrode terminal 24, which is insulated and mounted on the housing 21. One end of the electrode assembly 22 has a tab 221. The electrode terminal 24 is electrically connected to the tab 221 of the electrode assembly 22 to output or input electrical energy of the battery cell 20.

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

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

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

[0162] Optionally, the structure in which the electrode terminal 24 is mounted on the housing 21 can be varied; for example, in Figure 3 and Figure 4In the embodiment, both of the electrode terminals 24 are mounted on the end cover 213 of the shell 21. Of course, the structure of the battery monomer 20 is not limited to this, and in other embodiments, the battery monomer 20 can also be of other structures, for example, both of the electrode terminals 24 can also be mounted on the shell body 212 of the shell 21, and similarly, both of the electrode terminals 24 can also be one mounted on the shell body 212 of the shell 21 and the other mounted on the end cover 213 of the shell 21.

[0163] In some embodiments, the battery monomer 20 can also include two current collecting members, both of which are arranged in the shell 21 and are spaced apart, and each of which is used to connect one electrode terminal 24 and the same-polarity tabs 221 in the plurality of electrode assemblies 22, so as to realize the electrical connection between the electrode terminal 24 and the electrode assembly 22, and facilitate the reduction of the assembly difficulty between the tab 221 and the electrode terminal 24.

[0164] Exemplarily, the material of the current collecting member can also be various, for example, the material of the current collecting member can be copper, iron, aluminum, steel or aluminum alloy, etc.

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

[0166] In the embodiment, the pressure relief mechanism 23 is arranged on the wall portion 211, and the pressure relief mechanism 23 and the wall portion 211 can be an integrally formed structure or a separately arranged structure. Exemplarily, in the Figure 3 and Figure 4 In the embodiment, the pressure relief mechanism 23 and the wall portion 211 are a separately arranged structure, and correspondingly, the wall portion 211 is provided with a pressure relief hole, and the pressure relief mechanism 23 is connected to the wall portion 211 and blocks the pressure relief hole, that is, the pressure relief mechanism 23 is a structure assembled on the wall portion 211 and blocks and covers the pressure relief hole, wherein the pressure relief hole penetrates through the wall portion 211 and communicates the inside and outside of the shell 21, so that the inside and outside of the shell 21 can be communicated with each other when the pressure relief mechanism 23 is actuated and cracked, so as to release the internal pressure of the battery monomer 20. Similarly, in the embodiment in which the pressure relief mechanism 23 and the wall portion 211 are separately arranged and connected, the structure in which the pressure relief mechanism 23 is connected to the wall portion 211 can also be various, for example, welding connection, clamping or bonding, etc.

[0167] Referring to Figure 5 , Figure 6 and Figure 7As shown, the pressure relief mechanism 23 can include a connecting portion 231, a weak portion 232, and a pressure relief portion 233, the weak portion 232 is a structure connecting the connecting portion 231 and the pressure relief portion 233, and the weak portion 232 is configured to be at least partially destroyed to release pressure when the pressure inside the shell 21 reaches a threshold value, that is, the pressure relief mechanism 23 is configured to be able to split along at least part of the weak portion 232 when the battery monomer 20 is relieved, so as to open the pressure relief portion 233 to release the internal pressure of the battery monomer 20.

[0168] It should be noted that in the embodiment in which the pressure relief mechanism 23 and the wall portion 211 are integrally formed, the connecting portion 231 is a part of the wall portion 211, and the connecting portion 231, the weak portion 232 and the pressure relief portion 233 are structures formed on the wall portion 211 by an integral molding process. In the embodiment in which the pressure relief mechanism 23 and the wall portion 211 are separately provided, the connecting portion 231 is connected to the wall portion 211, and the connecting structure can be a welding connection or the like.

[0169] Exemplarily, referring to Figure 5 , Figure 6 and Figure 7 As shown, the pressure relief mechanism 23 is provided with a pressure relief groove 234 on at least one side in the thickness direction X of the wall portion, and the area of the pressure relief mechanism 23 provided with the pressure relief groove 234 is the weak portion 232, that is, in the projection plane perpendicular to the thickness direction X of the wall portion, the area of the pressure relief mechanism 23 located in the orthographic projection of the groove wall surface of the pressure relief groove 234 is the weak portion 232, and the groove wall surface of the pressure relief groove 234 includes the groove side surface and the groove bottom surface of the pressure relief groove 234. Correspondingly, in the thickness direction X of the wall portion, the area of the pressure relief mechanism 23 corresponding to the groove side surface and the groove bottom surface of the pressure relief groove 234 is the weak portion 232.

[0170] Exemplarily, the pressure relief groove 234 is provided on the side of the pressure relief mechanism 23 away from the electrode assembly 22 in the thickness direction X of the wall portion, and the pressure relief groove 234 on the pressure relief mechanism 23 is a groove structure formed by a stamping process.

[0171] The weak portion 232 is arranged around the pressure relief portion 233, and the weak portion 232 connects the connecting portion 231 and the pressure relief portion 233, that is, the weak portion 232 is a ring structure connected head to tail, and correspondingly, the pressure relief groove 234 is also a ring groove connected head to tail, and the weak portion 232 is arranged around the pressure relief portion 233, so that the connecting portion 231 is also a structure arranged outside the weak portion 232, and the weak portion 232 is connected between the connecting portion 231 and the pressure relief portion 233. Correspondingly, the pressure relief portion 233 is an area enclosed by the weak portion 232, that is, the area enclosed by the weak portion 232 is the pressure relief portion 233 of the pressure relief mechanism 23, and after at least part of the weak portion 232 is destroyed when the pressure inside the shell 21 reaches a threshold value, the pressure relief portion 233 can be opened to release the internal pressure of the battery monomer 20.

[0172] Optionally, the weakened portion 232 comprises two straight line segments 2321 and two arc line segments 2322, the two straight line segments 2321 are oppositely arranged along the first direction Y and the straight line segments 2321 extend along the second direction Z, the two arc line segments 2322 are oppositely arranged along the second direction Z and the arc line segments 2322 extend along an arc trajectory, one straight line segment 2321, one arc line segment 2322, another straight line segment 2321 and another arc line segment 2322 are sequentially connected in order, the first direction Y, the second direction Z and the thickness direction X of the wall portion are perpendicular to each other.

[0173] Exemplarily, the two arc line segments 2322 are both arc-shaped structures extending along a circular arc trajectory.

[0174] Exemplarily, in combination with the figures shown in Figure 4 and Figure 5 , the first direction Y is also the length direction of the battery monomer 20, correspondingly, the second direction Z is the thickness direction of the battery monomer 20, and the thickness direction X of the wall portion is the height direction of the battery monomer 20, that is, the arrangement direction of the two straight line segments 2321 is consistent with the length direction of the battery monomer 20, and the extension direction of the straight line segments 2321 is consistent with the thickness direction of the battery monomer 20, correspondingly, the two arc line segments 2322 are oppositely arranged along the thickness direction of the battery monomer 20, of course, the structure of the battery monomer 20 is not limited to this, in other embodiments, the first direction Y can also be the thickness direction of the battery monomer 20, correspondingly, the second direction Z is the length direction of the battery monomer 20, that is, the arrangement direction of the two straight line segments 2321 is consistent with the thickness direction of the battery monomer 20, and the extension direction of the straight line segments 2321 is consistent with the length direction of the battery monomer 20.

[0175] The pressure relief portion 233 has at least one thinned area 2331, and the thinned area 2331 is in a strip shape, that is, the pressure relief portion 233 is formed with at least one thinned area 2331 with weakened structural strength, and the thinned area 2331 is in a strip shape extending along a straight line trajectory, an arc trajectory or a broken line trajectory, etc.

[0176] Exemplarily, in the Figure 5 , both ends of the thinned area 2331 in the extension direction thereof are connected to the weakened portion 232, that is, both free ends of the thinned area 2331 are connected to the weakened portion 232, so that the thinned area 2331 divides the pressure relief portion 233 into multiple areas, so as to reduce the structural strength of the pressure relief portion 233, thereby facilitating the pressure relief portion 233 to release the stress generated by the internal gas pressure through deformation in the cyclic charging and discharging process of the battery monomer 20, so that the pressure relief portion 233 has the function of “breathing”.

[0177] Exemplarily, referring to Figure 5 , Figure 6 and Figure 8As shown, the pressure relief portion 233 is provided with a thinning groove 2332 on at least one side in the thickness direction X of the wall portion, and the area of the pressure relief portion 233 provided with the thinning groove 2332 is the thinning area 2331, that is, in the projection plane perpendicular to the thickness direction X of the wall portion, the area of the pressure relief portion 233 located in the orthogonal projection of the groove wall surface of the thinning groove 2332 is the thinning area 2331, and the groove wall surface of the thinning groove 2332 includes the groove side surface and the groove bottom surface of the pressure relief groove 234. Correspondingly, in the thickness direction X of the wall portion, the area of the pressure relief portion 233 corresponding to the groove side surface and the groove bottom surface of the thinning groove 2332 is the thinning area 2331. It should be noted that in the embodiment in which the pressure relief mechanism 23 is provided with the pressure relief groove 234, both ends of the thinning groove 2332 are connected to the pressure relief groove 234.

[0178] Exemplarily, the thinning groove 2332 is provided on the side of the pressure relief portion 233 away from the electrode assembly 22 in the thickness direction X of the wall portion, so that the thinning groove 2332 and the pressure relief groove 234 are both located on the same side of the pressure relief mechanism 23 in the thickness direction X of the wall portion, and the thinning groove 2332 on the pressure relief portion 233 is a groove structure formed by a stamping process.

[0179] Exemplarily, in the embodiment in which the pressure relief portion 233 is provided with the thinning groove 2332, Figure 5 the thinning area 2331 is a strip-shaped structure extending along an arc trajectory, and both ends of the thinning area 2331 in the extension direction are connected to the weak portion 232. Correspondingly, the thinning groove 2332 is also an arc-shaped groove structure extending along an arc trajectory. Of course, in other embodiments, the thinning area 2331 can also be a strip-shaped structure extending along a straight line trajectory or a broken line trajectory, etc.

[0180] Exemplarily, in the embodiment in which the pressure relief portion 233 is provided with the thinning groove 2332, Figure 5 the pressure relief portion 233 is provided with two thinning areas 2331, and the two thinning areas 2331 are oppositely arranged along the first direction Y, and in the projection plane perpendicular to the thickness direction X of the wall portion, the orthogonal projection of the two thinning areas 2331 is a structure symmetrically arranged with the geometric center of the orthogonal projection of the pressure relief portion 233 as the center. Of course, in other embodiments, the number of thinning areas 2331 provided on the pressure relief portion 233 can also be one, three or four, etc.

[0181] The minimum thickness of the thinning area 2331 is greater than the minimum thickness of the weak portion 232, that is, the minimum residual thickness of the pressure relief groove 234 is less than the minimum residual thickness of the thinning groove 2332, so that the structural strength of the weak portion 232 is weaker than that of the thinning area 2331.

[0182] It should be noted that the minimum thickness of the weakened portion 232 in the thickness direction X of the wall portion is the thickness of the groove bottom wall of the pressure relief groove 234 corresponding to the region with the maximum groove depth, that is, the minimum thickness of the groove bottom wall of the pressure relief groove 234. If the groove bottom surface of the pressure relief groove 234 is a flat surface, the minimum thickness of the weakened portion 232 in the thickness direction X of the wall portion is the thickness of the groove bottom wall of the pressure relief groove 234. If the groove bottom surface of the pressure relief groove 234 is an arc surface or an inclined surface, the minimum thickness of the weakened portion 232 in the thickness direction X of the wall portion is the thickness of the groove bottom wall of the pressure relief groove 234 at the position of the lowest point of the groove bottom surface of the pressure relief groove 234. Similarly, the minimum thickness of the thinned region 2331 in the thickness direction X of the wall portion is the thickness of the groove bottom wall of the thinned groove 2332 corresponding to the region with the maximum groove depth, that is, the minimum thickness of the groove bottom wall of the thinned groove 2332. If the groove bottom surface of the thinned groove 2332 is a flat surface, the minimum thickness of the thinned region 2331 in the thickness direction X of the wall portion is the thickness of the groove bottom wall of the thinned groove 2332. If the groove bottom surface of the thinned groove 2332 is an arc surface or an inclined surface, the minimum thickness of the thinned region 2331 in the thickness direction X of the wall portion is the thickness of the groove bottom wall of the thinned groove 2332 at the position of the lowest point of the groove bottom surface of the thinned groove 2332.

[0183] In the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the thinned region 2331 does not pass through the geometric center of the orthographic projection of the pressure relief portion 233, that is, in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the thinned region 2331 and the geometric center of the orthographic projection of the pressure relief portion 233 do not overlap. Correspondingly, in the projection plane perpendicular to the thickness direction X of the wall portion, the minimum distance between the geometric center of the orthographic projection of the pressure relief portion 233 and the orthographic projection of the thinned region 2331 is L1, then L1>0, that is, in the projection plane perpendicular to the thickness direction X of the wall portion, the geometric center of the orthographic projection of the pressure relief portion 233 and the orthographic projection of the pressure relief portion 233 are arranged in a spaced manner.

[0184] wherein L1 is: in the projection plane perpendicular to the thickness direction X of the wall portion, the minimum distance from the geometric center of the orthographic projection of the pressure relief portion 233 to the orthographic projection of the thinned region 2331 in the direction in which the geometric center of the orthographic projection of the pressure relief portion 233 points to the outer contour of the orthographic projection of the pressure relief portion 233.

[0185] It should be noted that the geometric center of the orthographic projection of the pressure relief portion 233 in the projection plane perpendicular to the thickness direction X of the wall portion is the geometric center of the plane defined by the outer contour of the orthographic projection of the pressure relief portion 233 in the projection plane perpendicular to the thickness direction X of the wall portion.

[0186] In the embodiment, the wall portion 211 of the shell 21 is provided with a pressure relief mechanism 23, the pressure relief mechanism 23 is provided with a weakened portion 232 configured to be at least partially destroyed to release pressure when the pressure inside the shell 21 reaches a threshold value, and a pressure relief portion 233 inside the weakened portion 232 is formed with a thinning area in a strip-shaped structure, so as to reduce the structural strength of the pressure relief portion 233, so that the pressure relief portion 233 can release stress in the form of deformation during the cyclic change of the internal gas pressure of the battery monomer 20, so that the pressure relief mechanism 23 has the function of “breathing”, which is beneficial to alleviate the risk of fatigue cracking of the weakened portion 232 of the pressure relief mechanism 23 during use. Wherein, by setting the minimum thickness of the thinning area 2331 to be greater than the minimum thickness of the weakened portion 232, and in the projection plane perpendicular to the thickness direction X of the wall portion, by setting the orthographic projection of the thinning area 2331 to not pass through the geometric center of the orthographic projection of the pressure relief portion 233, so that the thinning area 2331 can be away from the area where the pressure relief portion 233 deforms most during use. Beneficial to alleviate the fatigue phenomenon of the thinning area 2331, so as to reduce the risk of further weakening the structural strength of the thinning area 2331, so as to alleviate the phenomenon that the ignition position of the pressure relief mechanism 23 appears in the thinning area 2331 when the battery monomer 20 occurs thermal runaway, and then effectively alleviate the phenomenon that the pressure relief area of the pressure relief mechanism 23 is insufficient when pressure relief, which is beneficial to reduce the risk of fire and explosion caused by the pressure relief mechanism 23 due to untimely pressure relief, so as to improve the use reliability of the battery monomer 20.

[0187] According to some embodiments of the present application, as shown in Figure 5 、 Figure 6 、 Figure 7 and Figure 8 , the minimum thickness of the weakened portion 232 is D1, and the minimum thickness of the thinning area 2331 is D2. In the projection plane perpendicular to the thickness direction X of the wall portion, the minimum distance between the geometric center of the orthographic projection of the pressure relief portion 233 and the orthographic projection of the thinning area 2331 is L1, and the maximum distance between the geometric center of the orthographic projection of the pressure relief portion 233 and the orthographic projection of the weakened portion 232 is L2.

[0188] Wherein, 0.06mm≤D1≤0.18mm and 0.26mm≤D2≤0.5mm, 0.1≤L1 / L2≤0.8; or 0.18mm<D1≤0.24mm and 0.35mm≤D2≤0.5mm, 0.1≤L1 / L2≤0.8; or 0.24mm<D1≤0.3mm and 0.45mm≤D2≤0.5mm, 0.1≤L1 / L2≤0.8.

[0189] In the embodiments of the present application, L2 is: in the projection plane perpendicular to the thickness direction X of the wall portion, the direction along the geometric center of the normal projection of the pressure relief portion 233 to the outer contour of the normal projection of the pressure relief portion 233, the maximum distance from the geometric center of the normal projection of the pressure relief portion 233 to the normal projection of the weak portion 232. Exemplarily, the size of the pressure relief portion 233 enclosed by the weak portion 232 in the second direction Z is greater than the size of the pressure relief portion 233 in the first direction Y. Correspondingly, L2 is: in the projection plane perpendicular to the thickness direction X of the wall portion, the maximum distance between the geometric center of the normal projection of the pressure relief portion 233 and the normal projection of the weak portion 232 along the second direction Z.

[0190] 0.06mm≤D1≤0.18mm and 0.26mm≤D2≤0.5mm, 0.1≤L1 / L2≤0.8; or 0.18mm

[0191] Exemplarily, the ratio of L1 and L2 can be 0.1, 0.11, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, 0.52, 0.55, 0.58, 0.6, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78 or 0.8, etc.

[0192] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail in combination with Comparative Examples 1-3 and Embodiment Examples 1-12. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0193] Comparative Example 1

[0194] 1) Preparation of the positive electrode sheet

[0195] LiNi 0.7 Co 0.1 Mn 0.1 O2, a conductive agent Super P, and a binder polyvinylidene fluoride (PVDF) in N-methyl pyrrolidone (NMP) to form a positive electrode slurry, wherein the solid content in the positive electrode slurry is 50 wt%, and the mass ratio of LiNi 0.7 Co 0.1 Mn 0.1 O2, Super P, and PVDF is 8:1:1, the positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil, and after drying at 85°C and cold pressing, the edges are cut, the sheet is cut, and the strips are separated, and then the sheet is dried at 85°C under vacuum conditions for 4h to form a positive electrode sheet.

[0196] 2) Preparation of the negative electrode sheet

[0197] Graphite, a conductive agent Super P, a thickening agent carboxymethyl cellulose (CMC), and an adhesive styrene butadiene rubber (SBR) are mixed uniformly in deionized water to form a negative electrode slurry, wherein the solid content in the negative electrode slurry is 30 wt%, and the mass ratio of graphite, silicon monoxide, Super P, CMC, and the adhesive styrene butadiene rubber (SBR) in the solid components is 88:7:3:2, the negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C, and then cold pressed, the edges are cut, the sheet is cut, and the strips are separated, and then the sheet is dried at 120°C under vacuum conditions for 12h to form a negative electrode sheet.

[0198] 3) Preparation of the electrolyte

[0199] In an argon atmosphere glove box (H2O <0.1 ppm, O2 <0.1 ppm), a fully dried electrolyte salt LiPF6 is dissolved in a mixed solvent (the mixed solvent includes ethylene carbonate (EC) and diethyl carbonate (DEC), and the ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed in a mass ratio of 50:50), and after mixing uniformly, a liquid electrolyte with a concentration of 1 mol / L is obtained.

[0200] 4) Separator

[0201] A 16μm polyethylene film is used as the separator.

[0202] 5) Preparation of the battery cell 20

[0203] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, with the separator between the positive and negative electrode sheets to separate the positive and negative electrodes, and the electrode assembly 22 is obtained by winding. The electrode assembly 22 is placed in the aluminum shell 21, and the electrolyte prepared above is injected into the dried shell 21. The battery monomer 20 is prepared by encapsulation, standing, formation, shaping, capacity testing, etc. The shell 21 of the battery monomer 20 is a rectangular structure, and a pressure relief mechanism 23 is provided on the wall 211 of the shell 21. The pressure relief mechanism 23 is provided with an annular pressure relief groove 234 on one side, and a thinning groove 2332 is provided in the area inside the pressure relief mechanism 23. The thinning groove 2332 extends along an arc trajectory, and the two ends of the thinning groove 2332 in the extension direction are connected with the pressure relief groove 234, so as to form a weak part 232 of annular structure in the area where the pressure relief mechanism 23 is provided with the pressure relief groove 234, and a thinning area 2331 is formed in the area where the pressure relief mechanism 23 is provided with the thinning groove 2332. In the comparative example 1, the minimum thickness D1 of the weak part 232 of the pressure relief mechanism 23 of the battery monomer 20 in the thickness direction X of the wall is 0.08 mm, the minimum thickness D2 of the thinning area 2331 in the thickness direction X of the wall is 0.26 mm, the minimum distance L1 between the geometric center of the front projection of the pressure relief part 233 and the front projection of the thinning area 2331 in the projection plane perpendicular to the thickness direction X of the wall is 0.525 mm, and the maximum distance L2 between the geometric center of the front projection of the pressure relief part 233 and the front projection of the weak part 232 is 10.5 mm.

[0204] The preparation methods of the battery monomers 20 of the comparative examples 2-3 and the examples 1-12 are the same as those of the comparative example 1, except that D1, D2, L1 and L2 are different, as shown in Table 1.

[0205] The thermal runaway experiments of D1, D2, L1 and L2 in different cases are carried out by the comparative examples 1-3 and the examples 1-12, and the ignition position of the pressure relief mechanism 23 when the battery monomer 20 is pressure relieved in thermal runaway. The specific experimental method is as follows:

[0206] (1) A heating film is provided in the shell 21 of the battery monomer 20, and the battery monomer 20 is made to run in thermal runaway by promoting the heating film;

[0207] (2) Before testing, the battery monomer 20 is charged to 80% SOC-100% SOC, and the temperature of the battery monomer 20 is ensured to be 25±2℃;

[0208] (3) Sensor arrangement:

[0209] a. Temperature sensing wire arrangement: one layer of Teflon is pasted on each of the two large faces, two sides, top cover two poles and explosion-proof valve area of the battery cell, and a temperature sensing wire is arranged above the Teflon, and then another layer of Teflon is pasted;

[0210] b. Voltage sampling line arrangement: A layer of Teflon is pasted on the outer shell 21 and the two electrode terminals 24 of the battery monomer 20, and a voltage sampling line is arranged above the Teflon, and then a layer of Teflon is pasted again;

[0211] c. Gas pipe arrangement: A hole is drilled on the wall part 211 of the outer shell 21, and the drilling position is at the center of the length direction of the wall part 211 on one side of the pressure relief mechanism 23, that is, the drilling position is on one side of the pressure relief mechanism 23 in the length direction of the wall part 211, and is located between the pressure relief mechanism 23 and the edge of the wall part 211, and then the gas pipe is inserted into the hole and sealed, and the gas pipe is connected with the air pressure sensor; (a hole is also drilled on the center of the side of the electric core to connect the gas pipe and the air pressure sensor)

[0212] d. The temperature sensing line, voltage sampling line and air pressure sensor are connected to the data acquisition instrument to collect and analyze data in real time, and the collection frequency of the data acquisition instrument is ≤0.02 seconds;

[0213] (4) Assembly fixture, so that the fixture completely covers the largest outer surface of the battery monomer 20, and the clamping force is 3000N, (the arrangement order of the fixture, heating plate and battery monomer 20 is: fixture + battery monomer 20 + fixture);

[0214] (5) Test, open the data acquisition instrument to collect temperature, voltage and air pressure data, and then trigger the battery monomer 20 with a power of 100W-500W to heat, until the battery monomer 20 occurs thermal runaway and the pressure relief mechanism 23 appears to burst open, and in the experiment, the pressure relief mechanism 23 is filmed throughout the process, and the detonation position of the pressure relief mechanism 23 is observed;

[0215] The determination standard of thermal runaway of the battery monomer 20: (a) the voltage of the trigger object decreases and decreases by more than 25% of the initial voltage; (b) the temperature of the detection point reaches the maximum working temperature specified by the manufacturer; (c) the temperature rise rate dT / dt of the detection point is ≥1℃ / s, and lasts for more than 3 seconds. When (a) and (c) are satisfied or (b) and (c) are satisfied, it is determined that the battery monomer 20 occurs thermal runaway, and the thermal runaway time of the battery monomer 20 is determined.

[0216] The valve opening determination standard of the pressure relief mechanism 23: when the air pressure decreases by more than 25%, it can be determined that the pressure relief mechanism 23 has been opened.

[0217] The experimental results of the comparative examples 1-3 and the examples 1-12 are shown in Table 1.

[0218] Table 1

[0219] Serial number [D1 (mm)] [D2 (mm)] [L1 (mm)] [L2 (mm)] [L1 / L2] Experimental results (position of initiation) Comparative Example 1 0.08 0.26 0.84 10.5 0.08 Thinned region 2331 Example 1 0.08 0.26 1.05 10.5 0.1 Weak portion 232 Example 2 0.08 0.26 2 10 0.2 Weak portion 232 Example 3 0.1 0.3 3.4 8.5 0.4 Weak portion 232 Example 4 0.18 0.35 6 7.5 0.8 Weak portion 232 Comparative Example 2 0.2 0.38 0.84 10.5 0.08 Thinned region 2331 Example 5 0.2 0.38 1.05 10.5 0.1 Weak portion 232 Example 6 0.2 0.38 2 10 0.2 Weak portion 232 Example 7 0.22 0.4 3.4 8.5 0.4 Weak portion 232 Example 8 0.24 0.45 6 7.5 0.8 Weak portion 232 Comparative Example 3 0.26 0.46 0.84 10.5 0.08 Thinned region 2331 Example 9 0.26 0.46 1.05 10.5 0.1 Weak portion 232 Example 10 0.26 0.46 2 10 0.2 Weak portion 232 Example 11 0.28 0.48 3.4 8.5 0.4 Weak portion 232 Example 12 0.3 0.5 6 7.5 0.8 Weak portion 232

[0220] As shown in Table 1, according to the experimental results of Comparative Examples 1-3 and Examples 1-12, when D1 and D2 meet the conditions and the ratio of L1 and L2 is less than 0.1, the detonation position of the pressure relief mechanism 23 appears in the thinned area 2331 of the pressure relief portion 233, which may cause the pressure relief area of the pressure relief mechanism 23 to be insufficient, and the battery monomer 20 is prone to fire and explosion due to untimely pressure relief. When D1 and D2 meet the conditions and the ratio of L1 and L2 is greater than or equal to 0.1, the detonation position of the pressure relief mechanism 23 appears in the weak portion 232, which can achieve normal pressure relief of the pressure relief mechanism 23, and is conducive to relieving the risk of fire and explosion of the battery monomer 20 due to untimely pressure relief, thereby improving the use reliability of the battery monomer 20. Therefore, when 0.06mm≤D1≤0.18mm and 0.26mm≤D2≤0.5mm, or 0.18mm<D1≤0.24mm and 0.35mm≤D2≤0.5mm, or 0.24mm<D1≤0.3mm and 0.45mm≤D2≤0.5mm, L1 / L2 is greater than or equal to 0.1, and when L1 / L2 reaches 0.1 and above, the detonation position of the pressure relief mechanism 23 appears in the weak portion 232. Therefore, in order to achieve the effect that the pressure relief portion 233 can release stress by deformation during the cyclic change of the internal pressure of the battery monomer 20, L1 / L2 is set to be less than or equal to 0.8.

[0221] In the present embodiment, when 0.06mm≤D1≤0.18mm and 0.26mm≤D2≤0.5mm, or 0.18mm<D1≤0.24mm and 0.35mm≤D2≤0.5mm, or 0.24mm<D1≤0.3mm and 0.45mm≤D2≤0.5mm, by setting the ratio of L1 and L2 to 0.1 to 0.8, it is conducive to improving the effect that the pressure relief portion 233 can release stress by deformation during the cyclic change of the internal pressure of the battery monomer 20, and adjusting the distance between the region with the largest deformation degree of the weak area and the pressure relief portion 233 during use, which is conducive to relieving the fatigue phenomenon of the thinned area 2331, thereby reducing the risk of weakening the structural strength of the thinned area 2331, relieving the phenomenon that the detonation position of the pressure relief mechanism 23 appears in the thinned area 2331 when the battery monomer 20 is in thermal runaway, and relieving the phenomenon that the pressure relief mechanism 23 has insufficient pressure relief area when pressure relief, which is conducive to reducing the risk of fire and explosion of the battery monomer 20 due to untimely pressure relief, thereby improving the use reliability of the battery monomer 20.

[0222] In some embodiments, referring to Figure 5 , Figure 6 , Figure 7 and Figure 8As shown, and in combination with Table 1, 0.2≤L1 / L2≤0.8.

[0223] In the present embodiment, when 0.06mm≤D1≤0.18mm and 0.26mm≤D2≤0.5mm, or 0.18mm

[0224] According to some embodiments of the present application, referring to Figure 5 As shown, in the projection plane perpendicular to the thickness direction X of the wall portion, at least one straight line passing through the geometric center of the normal projection of the pressure relief portion 233 does not intersect with the normal projection of the thinning region 2331. That is, in the projection plane perpendicular to the thickness direction X of the wall portion, when the normal projection of the thinning region 2331 is a strip-shaped structure extending along an arc or a polyline, the geometric center of the normal projection of the pressure relief portion 233 is located outside the normal projection of the thinning region 2331, so that the geometric center of the normal projection of the pressure relief portion 233 is not covered by the normal projection of the thinning region 2331.

[0225] In the present embodiment, in the projection plane perpendicular to the thickness direction X of the wall portion, by setting at least one straight line passing through the geometric center of the normal projection of the pressure relief portion 233 to not intersect with the normal projection of the thinning region 2331, the geometric center of the normal projection of the pressure relief portion 233 is located outside the thinning region 2331. The pressure relief mechanism 23 adopting such a structure is advantageous in facilitating machining, reducing the forming difficulty of the thinning region 2331, and facilitating the formation of multiple thinning regions 2331 on the pressure relief portion 233, and on the other hand, can reduce the influence of the region with the largest deformation degree of the pressure relief portion 233 on multiple positions of the thinning region 2331 during use, thereby effectively alleviating the fatigue phenomenon of the thinning region 2331 to further reduce the risk of weakening the structural strength of the thinning region 2331, so that when the battery monomer 20 occurs thermal runaway, the phenomenon of the initiation position of the pressure relief mechanism 23 appearing in the thinning region 2331 can be further alleviated.

[0226] In some embodiments, referring to Figure 5As shown, in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the thinning region 2331 is located on at least one side of the geometric center of the orthographic projection of the pressure relief portion 233 in the first direction Y, where the first direction Y is perpendicular to the thickness direction X of the wall portion.

[0227] The orthographic projection of the thinning region 2331 is located on at least one side of the geometric center of the orthographic projection of the pressure relief part 233 in the first direction Y. That is, in the first direction Y, the thinning region 2331 may be provided on only one side of the geometric center of the orthographic projection of the pressure relief part 233, or the thinning region 2331 may be provided on both sides of the geometric center of the orthographic projection of the pressure relief part 233.

[0228] For example, in Figure 5 In the first direction Y, thinning regions 2331 are provided on both sides of the geometric center of the orthographic projection of the pressure relief part 233. Correspondingly, the pressure relief part 233 is provided with two thinning regions 2331, and in the projection plane perpendicular to the thickness direction X of the wall, the geometric center of the orthographic projection of the pressure relief part 233 is located between the orthographic projections of the two thinning regions 2331 in the first direction Y.

[0229] In this embodiment, by setting the thinning region 2331 to at least one side of the geometric center of the pressure relief section 233 in the first direction Y, it is convenient to set at least one straight line passing through the geometric center of the orthographic projection of the pressure relief section 233 to not intersect with the orthographic projection of the thinning region 2331, so that the geometric center of the orthographic projection of the pressure relief section 233 is located outside the thinning region 2331. On the other hand, it can further reduce the impact of the area with the greatest deformation of the pressure relief section 233 during use on multiple positions of the thinning region 2331, thereby further mitigating the fatigue phenomenon of the thinning region 2331 and further reducing the risk of weakening the structural strength of the thinning region 2331. This also helps to further mitigate the phenomenon that the explosion position of the pressure relief mechanism 23 appears in the thinning region 2331 when the battery cell 20 experiences thermal runaway.

[0230] According to some embodiments of this application, see Figure 5 As shown, the thinning region 2331 is connected to the weak portion 232 at both ends in its extension direction. That is, the pressure relief portion 233 is divided into multiple regions by the thinning region 2331, such that in the projection plane perpendicular to the thickness direction X of the wall, the orthographic projection of the thinning region 2331 is connected to the orthographic projection of the weak portion 232 at both ends in its extension direction.

[0231] In one embodiment where a pressure relief groove 234 is provided on the pressure relief mechanism 23 to form a weak part 232, and a thinning groove 2332 is provided on the pressure relief part 233 to form a thinning area 2331, the pressure relief groove 234 and the thinning groove 2332 are connected to each other and communicate with each other.

[0232] In the embodiment, by setting both ends of the thinning area 2331 in the extension direction thereof to be connected with the weak portion 232, on the one hand, it is convenient to form the thinning area 2331 and the weak portion 232 on the pressure relief mechanism 23, which is conducive to reducing the processing difficulty of the pressure relief mechanism 23, and on the other hand, the pressure relief portion 233 located on the inner side of the weak portion 232 can be divided into multiple areas through the thinning area 2331, which is conducive to further improving the effect that the pressure relief portion 233 can release stress in the form of deformation in the process of cyclic change of the internal gas pressure of the battery monomer 20, so as to further alleviate the risk of fatigue cracking of the weak portion 232 of the pressure relief mechanism 23 in the use process.

[0233] According to some embodiments of the present application, referring to Figure 5 As shown in the figure, in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the thinning area 2331 extends along an arc trajectory.

[0234] Exemplarily, the orthographic projection of the thinning area 2331 in the projection plane perpendicular to the thickness direction X of the wall portion is a structure extending along a circular arc trajectory.

[0235] In the embodiment, by setting the orthographic projection of the thinning area 2331 in the projection plane perpendicular to the thickness direction X of the wall portion to extend along an arc trajectory, the thinning area 2331 is a strip-shaped structure extending along an arc trajectory, so as to reduce the structural strength of the pressure relief portion 233, thereby enabling the pressure relief portion 233 to release stress in the form of deformation in the process of cyclic change of the internal gas pressure of the battery monomer 20, so as to alleviate the risk of fatigue cracking of the weak portion 232 of the pressure relief mechanism 23 in the use process.

[0236] According to some embodiments of the present application, referring to Figure 5 As shown in the figure, the pressure relief portion 233 is provided with two thinning areas 2331, the two thinning areas 2331 are oppositely arranged along the first direction Y, and in the projection plane perpendicular to the thickness direction X of the wall portion, the geometric center of the orthographic projection of the pressure relief portion 233 is located between the orthographic projections of the two thinning areas 2331 in the first direction Y, and the first direction Y is perpendicular to the thickness direction X of the wall portion.

[0237] Among them, the two thinning areas 2331 are oppositely arranged along the first direction Y, that is, the bending direction of the orthographic projection of the two thinning areas 2331 in the projection plane perpendicular to the thickness direction X of the wall portion is opposite, that is, in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of one thinning area 2331 is a structure bending in the first direction Y to approach the orthographic projection of the other thinning area 2331.

[0238] The geometric center of the front projection of the pressure relief portion 233 is located between the front projections of the two thinning regions 2331 in the first direction Y, that is, in the projection plane perpendicular to the thickness direction X of the wall portion, the front projections of the two thinning regions 2331 are respectively located on both sides of the geometric center of the front projection of the pressure relief portion 233 in the first direction Y.

[0239] In the present embodiment, by providing two thinning regions 2331 on the pressure relief portion 233 which are oppositely arranged along the first direction Y, and setting the geometric center of the pressure relief portion 233 to be located between the two thinning regions 2331 in the first direction Y, the stress releasing effect by deformation during the cyclic change of the internal gas pressure of the battery monomer 20 can be achieved while the two thinning regions 2331 are away from the region of the pressure relief portion 233 which deforms most during use, which is beneficial to alleviate the fatigue phenomenon of the thinning regions 2331, and further reduce the phenomenon that the initiation position of the pressure relief mechanism 23 appears in the thinning regions 2331 when the battery monomer 20 undergoes thermal runaway, which is beneficial to reduce the risk of fire and explosion caused by the pressure relief mechanism 23 due to untimely pressure relief, so as to improve the use reliability of the battery monomer 20.

[0240] In some embodiments, referring to Figure 5 As shown, the weakened portion 232 can include two straight line segments 2321 and two arc line segments 2322, the two straight line segments 2321 are oppositely arranged along the first direction Y and extend along the second direction Z, the two arc line segments 2322 are oppositely arranged along the second direction Z and extend along an arc line trajectory, one straight line segment 2321, one arc line segment 2322, another straight line segment 2321 and another arc line segment 2322 are sequentially connected in order, the first direction Y, the second direction Z and the thickness direction X of the wall portion are perpendicular to each other. The two ends of the thinning region 2331 in its extension direction are respectively connected to the two arc line segments 2322.

[0241] Wherein, one straight line segment 2321, one arc line segment 2322, another straight line segment 2321 and another arc line segment 2322 are sequentially connected in order, that is, the two straight line segments 2321 and the two arc line segments 2322 of the weakened portion 232 are alternately arranged and connected along the extension direction of the weakened portion 232.

[0242] It should be noted that the arc line segment 2322 of the weakened portion 232 is a structure extending along an arc line trajectory, and correspondingly, the straight line segment 2321 of the weakened portion 232 is a structure extending along a straight line trajectory, for example, in Figure 5In the specific embodiment, the arc segment 2322 is a structure extending along a circular arc track, and the straight segment 2321 is a structure extending along the second direction Z, wherein the two ends of the arc segment 2322 in the extending direction thereof are connected to the two straight segments 2321 respectively, and in the projection plane perpendicular to the thickness direction X of the wall portion, the two arc segments 2322 are arranged in axial symmetry with the straight line extending along the first direction Y.

[0243] The two ends of the thinning region 2331 in the extending direction thereof are connected to the two arc segments 2322 respectively, that is, one end of the thinning region 2331 extending along the arc track is connected to one arc segment 2322, and the other end is connected to the other arc segment 2322, so that the one straight segment 2321, the part of one arc segment 2322, the part of the other arc segment 2322 and the thinning region 2331 enclose a ring structure connected end to end.

[0244] In the specific embodiment, by connecting the two ends of the thinning region 2331 in the extending direction thereof to the two arc segments 2322 of the weak portion 232 respectively, the thinning region 2331 can divide the pressure relief portion 233 located on the inner side of the weak portion 232 into multiple regions, and can expand the length dimension of the thinning region 2331, thereby facilitating further improving the effect that the pressure relief portion 233 can release stress by deformation in the process of cyclic change of the internal gas pressure of the battery monomer 20, to further alleviate the risk of fatigue cracking of the weak portion 232 of the pressure relief mechanism 23 in the process of use.

[0245] It should be noted that the structure of the battery monomer 20 is not limited to this, and in some embodiments, the battery monomer 20 can also be other structures, for example, the weak portion 232 can include two straight segments 2321 and two arc segments 2322, the two straight segments 2321 are oppositely arranged along the first direction Y and extend along the second direction Z, the two arc segments 2322 are oppositely arranged along the second direction Z and extend along the arc track, the one straight segment 2321, the one arc segment 2322, the other straight segment 2321 and the other arc segment 2322 are connected end to end in sequence, and the first direction Y, the second direction Z and the thickness direction X of the wall portion are perpendicular to each other. The two ends of the thinning region 2331 in the extending direction thereof are connected to the same straight segment 2321.

[0246] In the specific embodiment, the two ends of the thinning region 2331 in the extending direction thereof are connected to the same straight segment 2321, that is, the two ends of the thinning region 2331 extending along the arc track are connected to the same straight segment 2321, so that the part of the one straight segment 2321 and the thinning region 2331 enclose a ring structure connected end to end.

[0247] In the embodiment, by connecting both ends of the thinning region 2331 in the extension direction thereof to the same straight line segment 2321, on the one hand, the pressure relief portion 233 located inside the weak portion 232 can be divided into multiple regions by the thinning region 2331, which is beneficial to further improve the effect that the pressure relief portion 233 can release stress by deformation during the cyclic change of the internal air pressure of the battery monomer 20, so as to further alleviate the risk of fatigue cracking of the weak portion 232 of the pressure relief mechanism 23 during use, and on the other hand, it is convenient to form the thinning region 2331 and the weak portion 232 on the pressure relief mechanism 23, which is beneficial to reduce the processing difficulty of the pressure relief mechanism 23.

[0248] According to some embodiments of the present application, please refer to Figure 9 , Figure 9 A front view of the pressure relief mechanism 23 in the thickness direction X of the wall portion is provided for still another embodiment of the present application. The thinning region 2331 can include a plurality of thinning segments 2331a connected in sequence, and in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of at least one thinning segment 2331a extends along an arc trajectory, and the orthographic projection of at least one thinning segment 2331a extends along a straight line trajectory.

[0249] Among them, the thinning region 2331 includes a plurality of thinning segments 2331a connected in sequence, that is, the thinning region 2331 is composed of a plurality of thinning segments 2331a, and the plurality of thinning segments 2331a are connected in sequence.

[0250] In the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of at least one thinning segment 2331a extends along an arc trajectory, and the orthographic projection of at least one thinning segment 2331a extends along a straight line trajectory, that is, the extension trajectory of the orthographic projection of part of the thinning segments 2331a in the plurality of thinning segments 2331a of the thinning region 2331 in the projection plane perpendicular to the thickness direction X of the wall portion is a straight line, and the extension trajectory of the orthographic projection of part of the thinning segments 2331a in the projection plane perpendicular to the thickness direction X of the wall portion is an arc.

[0251] Exemplarily, in Figure 9 , the thinning region 2331 includes three thinning segments 2331a, two of the three thinning segments 2331a have a straight line as the extension trajectory of the orthographic projection in the projection plane perpendicular to the thickness direction X of the wall portion, and the other thinning segment 2331a has an arc as the extension trajectory of the orthographic projection in the projection plane perpendicular to the thickness direction X of the wall portion.

[0252] In the embodiment, by setting the thinning region 2331 to include a plurality of thinning sections 2331a connected in sequence, and in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of at least one of the plurality of thinning sections 2331a is set to extend along an arc trajectory, and the orthographic projection of at least one of the thinning sections 2331a is set to extend along a straight line trajectory, so as to form a thinning region 2331 of a strip-shaped structure of different shapes, which is conducive to being applicable to pressure relief mechanisms 23 of different structures.

[0253] In some embodiments, please continue to refer to Figure 9 As shown, the thinning sections 2331a of the thinning region 2331 are three. In the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the thinning section 2331a located in the middle of the three thinning sections 2331a extends along an arc trajectory, and the orthographic projection of the thinning sections 2331a located at both ends of the three thinning sections 2331a extends along a straight line trajectory.

[0254] Exemplarily, one end of the thinning sections 2331a located at both ends of the three thinning sections 2331a is connected with the weak portion 232, and the other end is connected with one end of the thinning section 2331a located in the middle of the three thinning sections 2331a.

[0255] Exemplarily, in the projection plane perpendicular to the thickness direction X of the wall portion, the extension direction of the orthographic projection of the thinning sections 2331a located at both ends of the three thinning sections 2331a is tangent to the extension direction of the orthographic projection of the thinning section 2331a located in the middle of the three thinning sections 2331a.

[0256] In the embodiment, by setting the thinning sections 2331a of the thinning region 2331 to be three, and in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the thinning section 2331a located in the middle of the three thinning sections 2331a is an arc trajectory, and the orthographic projection of the thinning sections 2331a located at both ends of the three thinning sections 2331a is a straight line trajectory, so as to facilitate improving the regularity of the shape of the thinning region 2331, and reducing the difficulty of forming thinning, so as to reduce the processing difficulty of the pressure relief mechanism 23.

[0257] According to some embodiments of the present application, please refer to Figure 10 As shown, Figure 10 The pressure relief mechanism 23 provided by some embodiments of the present application is a front view in the thickness direction X of the wall portion. The thinning region 2331 can include a plurality of thinning sections 2331a connected in sequence, and in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the thinning sections 2331a extends along a straight line trajectory, and the extension directions of the orthographic projections of two adjacent thinning sections 2331a intersect.

[0258] The orthographic projection of the thinning section 2331a in the projection plane perpendicular to the thickness direction X of the wall portion extends along a straight line, and the extension directions of the orthographic projections of two adjacent thinning sections 2331a intersect, that is, the orthographic projection of each thinning section 2331a of the thinning region 2331 in the projection plane perpendicular to the thickness direction X of the wall portion is a strip-shaped structure extending along a straight line, and each two adjacent thinning sections 2331a are arranged at an acute angle, a right angle or an obtuse angle, so that the thinning region 2331 is a strip-shaped structure extending along a broken line.

[0259] Optionally, the number of thinning sections 2331a of the thinning region 2331 extending along a broken line can be two, three, four, five or six, etc.

[0260] Exemplarily, in the projection plane perpendicular to the thickness direction X of the wall portion, the thinning region 2331 is a strip-shaped structure extending along a straight line. Figure 10 In the projection plane perpendicular to the thickness direction X of the wall portion, the thinning region 2331 is a strip-shaped structure extending along a straight line.

[0261] In the embodiment, by setting the thinning region 2331 to include a plurality of thinning sections 2331a connected in sequence, in the projection plane perpendicular to the thickness direction X of the wall portion, the thinning section 2331a is a structure extending along a straight line, and the extension directions of the orthographic projections of each two adjacent thinning sections 2331a are intersecting structures, to form a thinning region 2331 in the shape of a broken line, which is beneficial to be applied to different structures of the pressure relief mechanism 23.

[0262] In some embodiments, please continue to refer to Figure 10 As shown in the figure, the thinning region 2331 has two thinning sections 2331a.

[0263] Exemplarily, one end of the two thinning sections 2331a is connected to each other, and the other end is connected to the weak portion 232.

[0264] In the embodiment, by setting the thinning region 2331 to have two thinning sections 2331a, the two thinning sections 2331a are connected and the extension directions are intersecting structures, to form a thinning region 2331 in the shape of a “V” structure, which is simple in structure and easy to manufacture, and is beneficial to reduce the manufacturing difficulty of the pressure relief mechanism 23.

[0265] It should be noted that the structure of the battery monomer 20 is not limited to this, in some embodiments, the battery monomer 20 can also be other structures, for example, in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the thinning region 2331 extends along a straight line.

[0266] In the embodiment, by setting the extending direction of the orthographic projection of the thinning region 2331 in the projection plane perpendicular to the thickness direction X of the wall portion as extending along a linear trajectory, the thinning region 2331 is facilitated to be formed on the pressure relief portion 233, which is conducive to reducing the processing difficulty of the pressure relief mechanism 23.

[0267] According to some embodiments of the present application, as shown in Figure 5 、 Figure 9 and Figure 10 , in the projection plane perpendicular to the thickness direction X of the wall portion, the position of the orthographic projection of the thinning region 2331 closest to the geometric center of the orthographic projection of the pressure relief portion 233 is the first position 2331b, and the position of the orthographic projection of the thinning region 2331 farthest from the geometric center of the orthographic projection of the pressure relief portion 233 is the second position 2331c, and the minimum thickness of the thinning region 2331 at the first position 2331b is greater than the minimum thickness of the thinning region 2331 at the second position 2331c.

[0268] The first position 2331b is: in the projection plane perpendicular to the thickness direction X of the wall portion, the position of the orthographic projection of the thinning region 2331 closest to the geometric center of the orthographic projection of the pressure relief portion 233.

[0269] The second position 2331c is: in the projection plane perpendicular to the thickness direction X of the wall portion, the position of the orthographic projection of the thinning region 2331 farthest from the geometric center of the orthographic projection of the pressure relief portion 233.

[0270] Exemplarily, in Figure 5 、 Figure 9 and Figure 10 , both ends of the thinning region 2331 are connected to the weak portion 232, and correspondingly, the position where the thinning region 2331 is connected to the weak portion 232 is the second position 2331c of the thinning region 2331.

[0271] The minimum thickness of the thinning region 2331 at the first position 2331b is greater than the minimum thickness of the thinning region 2331 at the second position 2331c, that is, in the cross section perpendicular to the extending direction of the thinning region 2331, the minimum thickness of the thinning region 2331 at the first position 2331b is greater than the minimum thickness of the thinning region 2331 at the second position 2331c.

[0272] In the embodiment, by setting the minimum thickness of the first position 2331b of the thinning area 2331 closest to the center area of the pressure relief part 233 to be greater than the minimum thickness of the second position 2331c of the thinning area 2331 farthest from the center area of the pressure relief part 233, the structural strength of the first position 2331b of the thinning area 2331 closest to the center area of the pressure relief part 233 is greater, thereby increasing the structural strength of the position of the thinning area 2331 close to the area of the pressure relief part 233 that generates the largest amount of deformation during use, so that while achieving the pressure relief part 233 capable of releasing stress through deformation to reduce the premature cracking of the weakening part 232, the phenomenon of cracking of the first position 2331b of the thinning area 2331 close to the center area of the pressure relief part 233 when the battery monomer 20 is in thermal runaway can be alleviated, to further alleviate the phenomenon of the initiation position of the pressure relief mechanism 23 appearing in the thinning area 2331, and further to alleviate the phenomenon of the pressure relief mechanism 23 appearing insufficient pressure relief area when pressure relief, which is beneficial to further reduce the risk of fire and explosion caused by the pressure relief mechanism 23 due to untimely pressure relief, to further improve the use reliability of the battery monomer 20.

[0273] According to some embodiments of the present application, referring to Figure 5 、 Figure 9 and Figure 10 , the minimum thickness of the thinning area 2331 in the cross section along the extension direction of the thinning area 2331 from the second position 2331c to the first position 2331b increases, and the cross section is perpendicular to the extension direction of the thinning area 2331. That is, the minimum thickness of the thinning area 2331 in the cross section perpendicular to the extension direction thereof is a structure that increases from the second position 2331c to the first position 2331b.

[0274] In the embodiment in which the pressure relief part 233 is provided with the thinning groove 2332 and forms the thinning area 2331, the minimum thickness of the thinning area 2331 in the cross section perpendicular to the extension direction thereof is the minimum residual thickness of the thinning groove 2332.

[0275] Optionally, the minimum thickness of the thinning area 2331 in the cross section along the extension direction of the thinning area 2331 from the second position 2331c to the first position 2331b is a structure that increases in steps, or can be a structure that gradually increases.

[0276] In the embodiment, by setting the minimum thickness of the thinning region 2331 in the cross section to gradually increase from the second position 2331c to the first position 2331b along the extension direction of the thinning region 2331, the structure is that the closer to the central region of the pressure relief portion 233, the greater the structural strength of the thinning region 2331, so that the structure that the closer to the region where the deformation amount of the pressure relief portion 233 is the largest during use, the greater the structural strength of the thinning region 2331 can be realized, so as to further alleviate the phenomenon that the closer to the central region of the pressure relief portion 233, the more prone to cracking of the thinning region 2331 when the battery monomer 20 is thermal runaway, so as to further reduce the risk of the initiation position of the pressure relief mechanism 23 appearing in the thinning region 2331.

[0277] In some embodiments, please continue to refer to Figure 5 , Figure 9 and Figure 10 , the minimum thickness of the thinning region 2331 in the cross section gradually increases from the second position 2331c to the first position 2331b along the extension direction of the thinning region 2331. That is, the minimum thickness of the thinning region 2331 in the cross section gradually and continuously increases from the second position 2331c to the first position 2331b along the extension direction of the thinning region 2331.

[0278] In the embodiment, by setting the minimum thickness of the thinning region 2331 in the cross section to gradually increase from the second position 2331c to the first position 2331b along the extension direction of the thinning region 2331, on the one hand, it is convenient to form the thinning region 2331 with different thicknesses, so as to realize the structure that the closer to the central region of the pressure relief portion 233, the greater the structural strength of the thinning region 2331, and is conducive to reducing the forming difficulty of the thinning region 2331, so as to reduce the manufacturing difficulty of the pressure relief mechanism 23, on the other hand, the structure that the closer to the central region of the pressure relief portion 233, the greater the structural strength of the thinning region 2331, so that the structure that the closer to the region where the deformation amount of the pressure relief portion 233 is the largest during use, the greater the structural strength of the thinning region 2331 can be realized, so as to further alleviate the phenomenon that the closer to the central region of the pressure relief portion 233, the more prone to cracking of the thinning region 2331 when the battery monomer 20 is thermal runaway, so as to further reduce the risk of the initiation position of the pressure relief mechanism 23 appearing in the thinning region 2331.

[0279] According to some embodiments of the present application, please refer to Figure 5As shown, the two ends of the thinning region 2331 in the extension direction thereof are connected to the weak portion 232, the thinning region 2331 comprises two first segments 2331d connected to each other, the connection position of the two first segments 2331d is the first position 2331b, the position where the first segment 2331d is connected to the weak portion 232 is the second position 2331c, and the lengths of the two first segments 2331d are equal in the extension direction of the thinning region 2331.

[0280] The first segment 2331d is a part of the thinning region 2331 in the extension direction thereof from one end of the thinning region 2331 connected to the weak portion 232 to the first position 2331b, so that the first position 2331b is also the connection position of the two first segments 2331d.

[0281] Exemplarily, in the projection plane perpendicular to the thickness direction X of the wall portion, the two first segments 2331d are arranged in an axisymmetric structure with an axis extending along the first direction Y and passing through the first position 2331b. Figure 5

[0282] In this embodiment, by arranging the two first segments 2331d formed by the thinning region 2331 with the first position 2331b as a boundary to have equal lengths, and by arranging the other ends of the two first segments 2331d to be connected to the weak portion 232, on the one hand, the shape regularity of the thinning region 2331 can be improved, which is beneficial to reducing the processing difficulty of the thinning region 2331, and on the other hand, the effect that the pressure relief portion 233 can release stress by deformation during the cyclic change of the internal gas pressure of the battery monomer 20 can be further improved.

[0283] According to some embodiments of the present application, referring to Figure 5 As shown, the weak portion 232 can comprise a first weak segment 232a and a second weak segment 232b connected in sequence, and the minimum thickness of the second weak segment 232b is greater than the minimum thickness of the first weak segment 232a.

[0284] The weak portion 232 comprises a first weak segment 232a and a second weak segment 232b connected in sequence, that is, the weak portion 232 of the annular structure is divided into the first weak segment 232a and the second weak segment 232b connected to each other, and the thickness of the second weak segment 232b is greater than the thickness of the first weak segment 232a, that is, the minimum thickness of the part of the weak portion 232 located in the second weak segment 232b in the thickness direction X of the wall portion is greater than the minimum thickness of the part of the weak portion 232 located in the first weak segment 232a in the thickness direction X of the wall portion. Similarly, in the embodiment in which the pressure relief mechanism 23 is provided with the pressure relief groove 234 and forms the weak portion 232, the minimum residual thickness of the region of the pressure relief groove 234 located in the second weak segment 232b is greater than the minimum residual thickness of the region of the pressure relief groove 234 located in the first weak segment 232a.​

[0285] In the present embodiment, by setting the minimum thickness of the second weak section 232b of the weak portion 232 to be greater than the minimum thickness of the first weak section 232a of the weak portion 232, the structural strength of the second weak section 232b is greater than that of the first weak section 232a, so that when the battery cell 20 is depressurized, the first weak section 232a can preferentially crack compared to the second weak section 232b, causing the pressure relief portion 233 to flip over about the second weak section 232b and open the pressure relief, which is beneficial to improving the smoothness of the pressure relief mechanism 23 of the battery cell 20, so as to improve the timeliness of the pressure relief of the battery cell 20.

[0286] In some embodiments, please continue to refer to Figure 5 As shown, the weak portion 232 includes two straight sections 2321 and two arc sections 2322, the two straight sections 2321 are oppositely arranged along the first direction Y and extend along the second direction Z, the two arc sections 2322 are oppositely arranged along the second direction Z and extend along an arc trajectory, one straight section 2321, one arc section 2322, another straight section 2321 and another arc section 2322 are sequentially connected in order, the first direction Y, the second direction Z and the thickness direction X of the wall portion are perpendicular to each other in pairs, the first weak section 232a includes two arc sections 2322 and one straight section 2321, and the second weak section 232b is another straight section 2321.

[0287] Among them, the two straight sections 2321 and the two arc sections 2322 of the weak portion 232 are alternately arranged and connected along the extension direction of the weak portion 232, and the two arc sections 2322 and the one straight section 2321 of the weak portion 232 constitute the first weak section 232a of the weak portion 232. Correspondingly, the other straight section 2321 of the weak portion 232 is the second weak section 232b of the weak portion 232.

[0288] It should be noted that in the embodiment in which the minimum thickness of the second weak section 232b is greater than the minimum thickness of the first weak section 232a, the minimum thickness of the straight section 2321 of the second weak section 232b in the thickness direction X of the wall portion is greater than the minimum thickness of the two arc sections 2322 and the other straight section 2321 in the thickness direction X of the wall portion.

[0289] In the embodiment, the first weakened section 232a includes two arc sections 2322 and one straight section 2321, the second weakened section 232b is another straight section 2321 of the weakened portion 232, and the one arc section 2322, the one straight section 2321, the other arc section 2322, and the other straight section 2321 are sequentially connected end to end. By arranging the two arc sections 2322 to extend along the arc track and oppositely arranged along the second direction Z, and arranging the two straight sections 2321 to extend along the second direction Z and oppositely arranged along the first direction Y, the battery monomer 20 with the structure has the following advantages. On the one hand, it is convenient to form the first weakened section 232a and the second weakened section 232b with different thicknesses on the pressure relief mechanism 23, which is beneficial to reduce the processing difficulty of the pressure relief mechanism 23. On the other hand, it can further improve the smoothness of the pressure relief portion 233 after the first weakened section 232a is cracked to flip around the second weakened section 232b as the axis, and is beneficial to further expand the flip angle of the pressure relief portion 233 of the pressure relief mechanism 23 inside the weakened portion 232, so as to further improve the pressure relief smoothness and the pressure relief rate of the battery monomer 20.

[0290] According to some embodiments of the present application, as shown in Figure 5 、 Figure 7 and Figure 8 , the minimum thickness of the weakened portion 232 is D1, the minimum thickness of the thinned area 2331 is D2, and 0.18≤D1 / D2≤0.62 is satisfied.

[0291] In the embodiment in which the pressure relief mechanism 23 is provided with the pressure relief groove 234 and forms the weakened portion 232, D1 is the minimum residual thickness of the pressure relief groove 234. Similarly, in the embodiment in which the pressure relief portion 233 is provided with the thinned groove 2332 and forms the thinned area 2331, D2 is the minimum residual thickness of the thinned groove 2332.

[0292] For example, the ratio of D1 and D2 can be 0.18, 0.19, 0.2, 0.21, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, 0.52, 0.55, 0.58, 0.6, 0.61, or 0.62, etc.

[0293] In the embodiment, by setting the minimum thickness of the weakened portion 232 to 0.18 to 0.62 of the minimum thickness of the thinned area 2331, on the one hand, the minimum thickness of the weakened portion 232 is set to be greater than or equal to 0.18 of the minimum thickness of the thinned area 2331, so as to alleviate the risk of early cracking of the weakened portion 232 due to too small minimum thickness of the weakened portion 232, and to improve the use reliability of the battery monomer 20, and on the other hand, the minimum thickness of the weakened portion 232 is set to be less than or equal to 0.62 of the minimum thickness of the thinned area 2331, so as to reduce the risk of the thinned area 2331 cracking preferentially to the weakened portion 232 when the battery monomer 20 is pressure released, so that the phenomenon of the initiation position of the pressure release mechanism 23 appearing in the thinned area 2331 can be further alleviated when the battery monomer 20 is in thermal runaway, thereby further alleviating the phenomenon of insufficient pressure release area of the pressure release mechanism 23 when pressure releasing, which is beneficial to further reducing the risk of fire and explosion caused by the pressure release mechanism 23 due to untimely pressure release, and further improving the use reliability of the battery monomer 20.

[0294] In some embodiments, as shown in FIG. 2A, the minimum thickness of the weakened portion 232 is D1, and 0.02mm≤D1≤0.24mm. Figure 7

[0295] For example, the minimum thickness D1 of the weakened portion 232 can be 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, 0.23mm or 0.24mm, etc.

[0296] In the embodiment, by setting the minimum thickness of the weakened portion 232 to 0.02mm to 0.24mm, on the one hand, the minimum thickness of the weakened portion 232 is set to be greater than or equal to 0.02mm, so as to alleviate the risk of early cracking of the weakened portion 232 due to too small minimum thickness of the weakened portion 232, and to improve the reliability of the battery monomer 20, and on the other hand, the minimum thickness of the weakened portion 232 is set to be less than or equal to 0.24mm, so as to reduce the burst pressure required by the pressure release mechanism 23 when pressure releasing, so as to reduce the risk of explosion or explosion of the battery monomer 20 when thermal runaway.

[0297] In some embodiments, as shown in FIG. 2A, the minimum thickness of the thinned area 2331 is D2, and 0.22mm≤D2≤0.38mm. Figure 8

[0298] ​​Exemplarily, the minimum thickness D2 of the thinning region 2331 can be 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.35 mm, 0.36 mm, 0.37 mm, or 0.38 mm, etc.

[0299] In the present embodiment, by setting the minimum thickness of the thinning region 2331 to be 0.22 mm to 0.38 mm, on the one hand, setting the minimum thickness of the thinning region 2331 to be greater than or equal to 0.22 mm can improve the structural strength of the thinning region 2331, so as to alleviate the phenomenon that the thinning region 2331 is preferentially cracked than the weak portion 232 when the battery cell 20 is depressurized, so that the phenomenon that the initiation position of the pressure relief mechanism 23 occurs in the thinning region 2331 when the battery cell 20 is in thermal runaway can be further alleviated, and on the other hand, setting the minimum thickness of the thinning region 2331 to be less than or equal to 0.38 mm can improve the weakening effect of the structural strength of the pressure relief portion 233, so that the pressure relief portion 233 can release stress by deformation during the cyclic change of the internal pressure of the battery cell 20, thereby further improving the “breathing” effect of the pressure relief mechanism 23 during use.

[0300] According to some embodiments of the present application, as shown in Figure 6 and Figure 7 , along the thickness direction X of the wall portion, at least part of the pressure relief portion 233 is raised towards or away from the electrode assembly 22 and forms a raised portion 2333, and the weak portion 232 is surrounded outside the raised portion 2333.

[0301] Among them, the raised portion 2333 is a raised structure of at least part of the pressure relief portion 233 raised in the thickness direction X of the wall portion towards or away from the electrode assembly 22, optionally, the pressure relief portion 233 can be a structure of locally raised to form the raised portion 2333, or a structure of integrally raised to form the raised portion 2333, exemplarily, in Figure 7 , the pressure relief portion 233 is a structure of locally raised, of course, in other embodiments, the pressure relief portion 233 can also be a structure of integrally raised, correspondingly, the pressure relief portion 233 is the raised portion 2333.

[0302] The weak portion 232 is surrounded outside the raised portion 2333, that is, the raised portion 2333 is located in the area enclosed by the weak portion 232.

[0303] Optionally, the raised portion 2333 can be a structure raised in the thickness direction X of the wall portion towards the electrode assembly 22, or a structure raised away from the electrode assembly 22.

[0304] In the embodiment, by arranging the bulging portion 2333 bulging towards or away from the electrode assembly 22 on the pressure relief portion 233 inside the weakened portion 232, and the weakened portion 232 surrounds the outside of the bulging portion 2333, on the one hand, the difficulty of processing the weakened portion 232 on the pressure relief mechanism 23 can be reduced, and the material flow form of the weakened portion 232 during processing is beneficial to be improved, so as to improve the processing consistency of the weakened portion 232, on the other hand, the bulging portion 2333 inside the weakened portion 232 forms a pre-deformation structure, so as to facilitate the cracking and pressure relief of the weakened portion 232 of the pressure relief mechanism 23 when the battery monomer 20 is in thermal runaway, thereby being able to increase the thickness of the weakened portion 232 under the same burst pressure, so as to alleviate the fatigue cracking and other phenomena of the weakened portion 232 during use, and thereby being able to effectively reduce the risk of the pressure relief mechanism 23 opening the valve in advance, so as to improve the service life and use reliability of the battery monomer 20.

[0305] In some embodiments, in combination with Figure 6 , Figure 7 and Figure 8 , the bulging portion 2333 includes at least part of the thinned area 2331, that is, part of the bulging portion 2333 forms at least part of the thinned area 2331, and in the embodiment in which the pressure relief portion 233 is provided with the thinned groove 2332 and forms the thinned area 2331, at least part of the thinned groove 2332 is arranged on the bulging portion 2333.

[0306] In the embodiment, by arranging the bulging portion 2333 to include at least part of the thinned area 2331, so that the thinned area 2331 is also at least partially bulging, thereby being able to further facilitate the pressure relief portion 233 to release stress in the form of deformation during the cyclic change of the internal gas pressure of the battery monomer 20, thereby being able to further improve the “breathing” effect of the pressure relief mechanism 23 during use.

[0307] According to some embodiments of the present application, referring to Figure 6 and Figure 7 , along the thickness direction X of the wall portion, the pressure relief mechanism 23 has opposite first and second surfaces 235 and 236, the first surface 235 is provided with a groove 2351, the groove bottom wall of the groove 2351 includes the weakened portion 232, and part of the groove bottom wall of the groove 2351 bulges in a direction pointing from the second surface 236 to the first surface 235 and forms the bulging portion 2333.

[0308] Among them, the first and second surfaces 235 and 236 are respectively the surfaces on both sides of the pressure relief mechanism 23 in the thickness direction X of the wall portion, and exemplarily, the first and second surfaces 235 and 236 are parallel to each other.

[0309] The first surface 235 is provided with a groove 2351, that is, the groove 2351 is a structure provided on the first surface 235 and recessed in a direction of the first surface 235 pointing to the second surface 236.

[0310] The groove bottom wall of the groove 2351 includes a weak portion 232, that is, the groove bottom wall of the groove 2351 forms the weak portion 232, and in the embodiment in which the pressure relief mechanism 23 is provided with the pressure relief groove 234 and forms the weak portion 232, the pressure relief groove 234 is a structure provided on the groove bottom wall of the groove 2351.

[0311] Part of the groove bottom wall of the groove 2351 is raised in a direction of the second surface 236 pointing to the first surface 235 and forms a raised portion 2333, that is, the raised portion 2333 is a structure raised in a direction of the interior of the groove 2351 in the thickness direction X of the wall portion.

[0312] In the present embodiment, by providing the groove 2351 on the first surface 235 of the pressure relief mechanism 23 and setting the raised portion 2333 as a structure raised in a direction of the second surface 236 pointing to the first surface 235, the battery monomer 20 adopting such a structure can realize that the raised portion 2333 is raised toward one side of the groove 2351, on the one hand, can realize that the groove 2351 and the raised portion 2333 share part of the space in the thickness direction X of the wall portion, which is beneficial to save the space occupied by the pressure relief mechanism 23, so as to improve the space utilization of the battery monomer 20, on the other hand, through the groove 2351, the raised portion 2333 can also be protected to some extent, so as to reduce the abrasion or knocking phenomenon of the raised portion 2333 in the use or assembly process.

[0313] In some embodiments, referring to Figure 4 , Figure 6 and Figure 7 , the second surface 236 faces the electrode assembly 22 in the thickness direction X of the wall portion. That is, the raised portion 2333 is a structure raised in a direction away from the electrode assembly 22 in the thickness direction X of the wall portion.

[0314] In the present embodiment, by setting the second surface 236 of the pressure relief mechanism 23 as a structure facing the electrode assembly 22, so that the raised portion 2333 is a structure raised in a direction away from the electrode assembly 22 in the thickness direction X of the wall portion, on the one hand, it can reduce the phenomenon that the raised portion 2333 occupies the internal space of the battery monomer 20, so as to improve the space inside the battery monomer 20 for accommodating the electrode assembly 22, which is beneficial to improve the energy density of the battery monomer 20, on the other hand, it can reduce the interference phenomenon between the raised portion 2333 and other components inside the battery monomer 20, which is beneficial to improve the use reliability of the battery monomer 20.

[0315] In some embodiments, referring toFigure 6 and Figure 7 As shown in FIGS. 12 and 13, the pressure relief mechanism 23 is provided with the pressure relief groove 234 and forms the weak portion 232, and in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the weak portion 232 and the orthographic projection of the groove wall surface of the pressure relief groove 234 overlap, and the pressure relief groove 234 is arranged on the groove bottom surface of the groove 2351.

[0316] In the embodiment, the weak portion 232 is formed on the pressure relief mechanism 23 by means of the pressure relief groove 234 arranged on the pressure relief mechanism 23, so as to reduce the difficulty of forming the weak portion 232 on the pressure relief mechanism 23, and by arranging the pressure relief groove 234 on the groove bottom surface of the groove 2351, the pressure relief groove 234 and the groove 2351 are both located on the same side of the pressure relief mechanism 23 in the thickness direction X of the wall portion, so that the pressure relief groove 234 can be machined synchronously with the machining of the groove 2351, which is conducive to reducing the difficulty of forming the pressure relief groove 234 on the pressure relief mechanism 23 and optimizing the production rhythm of the battery monomer 20.

[0317] According to some embodiments of the present application, referring to Figure 6 and Figure 7 As shown in FIGS. 12 and 13, the pressure relief mechanism 23 is provided with the pressure relief groove 234 and forms the weak portion 232, and in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the weak portion 232 and the orthographic projection of the groove wall surface of the pressure relief groove 234 overlap, and the pressure relief groove 234 is arranged on the groove bottom surface of the groove 2351.

[0318] In the embodiment, the weak portion 232 is formed on the pressure relief mechanism 23 by means of the pressure relief groove 234 arranged on the pressure relief mechanism 23, so as to reduce the difficulty of forming the weak portion 232 on the pressure relief mechanism 23, and by arranging the pressure relief groove 234 on the groove bottom surface of the groove 2351, the pressure relief groove 234 and the groove 2351 are both located on the same side of the pressure relief mechanism 23 in the thickness direction X of the wall portion, so that the pressure relief groove 234 can be machined synchronously with the machining of the groove 2351, which is conducive to reducing the difficulty of forming the pressure relief groove 234 on the pressure relief mechanism 23 and optimizing the production rhythm of the battery monomer 20.

[0319] According to some embodiments of the present application, referring to Figure 6 and Figure 8 As shown in FIGS. 12 and 13, the pressure relief mechanism 23 is provided with the pressure relief groove 234 and forms the weak portion 232, and in the projection plane perpendicular to the thickness direction X of the wall portion, the orthographic projection of the weak portion 232 and the orthographic projection of the groove wall surface of the pressure relief groove 234 overlap, and the pressure relief groove 234 is arranged on the groove bottom surface of the groove 2351.

[0320] In the embodiment, the weak portion 232 is formed on the pressure relief mechanism 23 by means of the pressure relief groove 234 arranged on the pressure relief mechanism 23, so as to reduce the difficulty of forming the weak portion 232 on the pressure relief mechanism 23, and by arranging the pressure relief groove 234 on the groove bottom surface of the groove 2351, the pressure relief groove 234 and the groove 2351 are both located on the same side of the pressure relief mechanism 23 in the thickness direction X of the wall portion, so that the pressure relief groove 234 can be machined synchronously with the machining of the groove 2351, which is conducive to reducing the difficulty of forming the pressure relief groove 234 on the pressure relief mechanism 23 and optimizing the production rhythm of the battery monomer 20.

[0321] According to some embodiments of the present application, referring to Figure 3 and Figure 4As shown, the pressure relief mechanism 23 is arranged separately from the wall portion 211, that is, the pressure relief mechanism 23 and the wall portion 211 of the shell 21 are two independent components, and correspondingly, the wall portion 211 is provided with a pressure relief hole, and the connecting portion 231 of the pressure relief mechanism 23 is connected to the wall portion 211 and the pressure relief mechanism 23 blocks the pressure relief hole.

[0322] The structure in which the connecting portion 231 is connected to the wall portion 211 of the shell 21 can be various, such as welding connection, clamping or bonding, etc.

[0323] In the embodiment, by arranging the pressure relief mechanism 23 and the wall portion 211 in a separate structure, the thin portion 232 and the thinned area 2331 can be formed on the pressure relief mechanism 23 first, and then the pressure relief mechanism 23 is assembled to the wall portion 211 of the shell 21, which is beneficial to reduce the forming difficulty of the pressure relief mechanism 23, and is beneficial to optimize the production rhythm of the battery monomer 20.

[0324] Of course, the structure of the battery monomer 20 is not limited to this, and in some embodiments, the battery monomer 20 can also be other structures, such as the pressure relief mechanism 23 and the wall portion 211 being integrally formed, and correspondingly, the thin portion 232 and the thin area being structures formed on the wall portion 211 by an integral forming process, such as stamping, and the connecting portion 231 being a part of the wall portion 211.

[0325] In the embodiment, by arranging the pressure relief mechanism 23 and the wall portion 211 in an integrally formed structure, that is, the pressure relief mechanism 23 and the wall portion 211 are an integral structure, the battery monomer 20 adopting this structure is beneficial to improve the structural strength of the pressure relief mechanism 23 connected to the wall portion 211, so as to reduce the risk of the pressure relief mechanism 23 falling off during use, thereby improving the use stability and reliability of the battery monomer 20.

[0326] According to some embodiments of the present application, referring to Figure 3 and Figure 4 As shown, the shell 21 can include a shell body 212 and an end cover 213, the shell body 212 includes an integrally formed side wall and a bottom wall, the side wall is surrounded around the bottom wall, one end of the side wall is connected to the bottom wall along the thickness direction X of the wall portion, and the other end is enclosed to form an opening 2121, the side wall and the bottom wall jointly define a containing cavity, and the electrode assembly 22 is contained in the containing cavity, and the end cover 213 closes the opening 2121, and the end cover 213 is the wall portion 211.

[0327] That is, the pressure relief mechanism 23 is arranged on the end cover 213 of the shell 21.

[0328] In the embodiment, by setting the wall portion 211 of the shell 21 as the end cover 213 used for closing the opening 2121, the battery monomer 20 with the structure facilitates setting the pressure relief mechanism 23 on the end cover 213, thereby facilitating reducing the manufacturing difficulty of the battery monomer 20 to improve the production efficiency of the battery monomer 20.

[0329] It should be noted that the structure of the battery monomer 20 is not limited thereto, and in some embodiments, the battery monomer 20 can also be other structures, for example, the shell 21 can include a shell body 212 and an end cover 213, the shell body 212 includes an integrally formed side wall and a bottom wall, the side wall is arranged around the bottom wall, and one end of the side wall is connected to the bottom wall in the thickness direction X of the wall portion, and the other end of the side wall is closed to form the opening 2121, the side wall and the bottom wall jointly define a containing cavity, the electrode assembly 22 is contained in the containing cavity, the end cover 213 closes the opening 2121, and the bottom wall is the wall portion 211. That is, the wall portion 211 is the bottom wall of the shell body 212 arranged opposite to the end cover 213 in the thickness direction X of the wall portion, that is, the pressure relief mechanism 23 is arranged on the bottom wall of the shell body 212.

[0330] The shell body 212 includes an integrally formed side wall and a bottom wall, that is, the shell body 212 is processed by an integrally forming process, such as stamping, casting or extrusion forming, and the like, that is, the side wall and the bottom wall of the shell body 212 are an integral structure.

[0331] In the embodiment, by setting the wall portion 211 of the shell 21 as the bottom wall of the shell body 212 arranged opposite to the end cover 213 in the thickness direction X of the wall portion, the battery monomer 20 with the structure can realize that the region of the shell 21 provided with the pressure relief mechanism 23 is away from the end cover 213, thereby effectively relieving the phenomenon that the stress generated by the mutual connection of the end cover 213 and the shell body 212 acts on the pressure relief mechanism 23, to reduce the influence on the pressure relief mechanism 23, and further facilitate reducing the risk of cracking or structural strength reduction of the weak portion 232 of the pressure relief mechanism 23 under the pulling action of the stress, to improve the service life and use reliability of the battery monomer 20.

[0332] According to some embodiments of the present application, the present application also provides a battery device 100, which includes the battery monomer 20 of any one of the above schemes.

[0333] As shown in Figure 2 The battery device 100 can also include a box body 10, and the battery monomer 20 is contained in the box body 10.

[0334] In some embodiments, the box 10 can include a first box body 11 and a second box body 12, the first box body 11 and the second box body 12 are mutually coverable, and the first box body 11 and the second box body 12 jointly define an assembly space for accommodating the battery monomer 20.

[0335] 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-shaped structure, the first box body 11 is coverable on the open side of the second box body 12, so that the first box body 11 and the second box body 12 jointly define the assembly space; the first box body 11 and the second box body 12 can also be hollow structures with one side open, and the open side of the first box body 11 is coverable on the open side of the second box body 12.

[0336] Of course, the box 10 formed by the first box body 11 and the second box body 12 can have various shapes, such as a cylinder or a cuboid, etc. Exemplarily, in the embodiment shown in Figure 2 , the box 10 is a cuboid structure.

[0337] Optionally, the battery monomer 20 arranged in the box 10 can be one or multiple. Exemplarily, in the embodiment shown in Figure 2 , the box 10 of the battery device 100 is arranged with multiple battery monomers 20, and the multiple battery monomers 20 can be in series connection, parallel connection or mixed connection, and the mixed connection means that the multiple battery monomers 20 have both series connection and parallel connection. The multiple battery monomers 20 can be directly connected in series, parallel or mixed connection, and the whole formed by the multiple battery monomers 20 is accommodated in the box 10; of course, the battery device 100 can also be that the multiple battery monomers 20 are first connected in series, parallel or mixed connection to form a battery module, and the multiple battery modules are connected in series, parallel or mixed connection to form a whole, and the whole is accommodated in the box 10.

[0338] Among them, the battery device 100 can also include other structures, for example, the battery device 100 can also include a busbar component, the busbar component is connected to the multiple battery monomers 20 to realize the electrical connection between the multiple battery monomers 20.

[0339] It should be noted that in some embodiments, the battery device 100 can also not be provided with the box 10, the battery device 100 includes multiple battery monomers 20, and the battery device 100 composed of the multiple battery monomers 20 can be directly assembled to the electric device to provide electric energy for the electric device by the multiple battery monomers 20. That is, the box 10 can be part of the electric device. Taking the vehicle 1000 as an example, the box 10 can be part of the chassis structure of the vehicle 1000, for example, part of the box 10 can be at least part of the floor of the vehicle 1000, or part of the box 10 can be at least part of the cross beam and the longitudinal beam of the vehicle 1000.

[0340] According to some embodiments of the present application, the present application also provides a power consuming device, the power consuming device comprising the battery cell 20 of any of the above solutions, and the battery cell 20 is used to provide electric energy for the power consuming device.

[0341] Wherein, the power consuming device can be the device or system of any of the above application battery cell 20.

[0342] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict.

[0343] The above is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. 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 by, The electrode assembly is accommodated in the shell. The pressure relief mechanism is arranged on the wall portion, and comprises a connecting portion, a weakened portion and a pressure relief portion. The connecting portion is connected with the wall portion. The weakened portion is arranged around the pressure relief portion and connects the connecting portion and the pressure relief portion. The weakened portion is configured to be at least partially destroyed to release the pressure when the pressure inside the shell reaches a threshold value. The pressure relief portion has at least one thinned area.

2. The battery cell of claim 1, wherein, The thinned area is in the shape of a strip. The minimum thickness of the thinned area is greater than the minimum thickness of the weakened portion. In a projection plane perpendicular to the thickness direction of the wall portion, the normal projection of the thinned area does not pass through the geometric center of the normal projection of the pressure relief portion. The minimum thickness of the weakened portion is D1, the minimum thickness of the thinned area is D2, in the projection plane perpendicular to the thickness direction of the wall portion, the minimum distance between the geometric center of the normal projection of the pressure relief portion and the normal projection of the thinned area is L1, and the maximum distance between the geometric center of the normal projection of the pressure relief portion and the normal projection of the weakened portion is L2.

3. The battery cell of claim 2, wherein, 0.06mm≤D1≤0.18mm and 0.26mm≤D2≤0.5mm, and 0.1≤L1 / L2≤0.8 is satisfied; or 4. The battery cell of claim 1, wherein, 0.18mm<D1≤0.24mm and 0.35mm≤D2≤0.5mm, and 0.1≤L1 / L2≤0.8 is satisfied; or 5. The battery cell of claim 4, wherein, 0.24mm<D1≤0.3mm and 0.45mm≤D2≤0.5mm, and 0.1≤L1 / L2≤0.8 is satisfied.

6. The battery cell of claim 1, wherein, 0.2≤L1 / L2≤0.

8.

7. The battery cell of claim 1, wherein, In the projection plane perpendicular to the thickness direction of the wall portion, at least one straight line passing through the geometric center of the normal projection of the pressure relief portion does not intersect the normal projection of the thinned area.

8. The battery cell of claim 7, wherein, In the projection plane perpendicular to the thickness direction of the wall portion, the normal projection of the thinned area is located on at least one side of the geometric center of the normal projection of the pressure relief portion in a first direction, and the first direction is perpendicular to the thickness direction of the wall portion.

9. The battery cell of claim 7, wherein, Both ends of the thinned area in its extension direction are connected to the weakened portion. In the projection plane perpendicular to the thickness direction of the wall portion, the normal projection of the thinned area extends along an arc trajectory. The pressure relief portion is provided with two thinned areas. The two thinned areas are oppositely arranged along a first direction, and the geometric center of the normal projection of the pressure relief portion is located between the normal projections of the two thinned areas in the first direction, and the first direction is perpendicular to the thickness direction of the wall portion. The weakened portion comprises two straight line segments and two arc line segments. The two straight line segments are oppositely arranged along a first direction and extend along a second direction. The two arc line segments are oppositely arranged along the second direction and extend along an arc trajectory. One straight line segment, one arc line segment, another straight line segment and another arc line segment are sequentially connected in a head-to-tail manner. The first direction, the second direction and the thickness direction of the wall portion are perpendicular to each other. Two ends of the thinning region in its extension direction are connected with two arc segments respectively; or Both ends of the thinning region in its extension direction are connected with the same straight segment.

10. The battery cell of claim 1, wherein, The thinning region comprises a plurality of thinning segments connected in sequence; In a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of at least one of the thinning segments extends along an arc trajectory, and the orthographic projection of at least one of the thinning segments extends along a straight line trajectory.

11. The battery cell of claim 10, wherein, The thinning segments of the thinning region are three; In a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of the thinning segment in the middle of the three thinning segments extends along an arc trajectory, and the orthographic projection of the thinning segments at both ends of the three thinning segments extends along a straight line trajectory.

12. The battery cell of claim 1, wherein, The thinning region comprises a plurality of thinning segments connected in sequence; In a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of the thinning segments extends along a straight line trajectory, and the extension directions of the orthographic projections of two adjacent thinning segments intersect.

13. The battery cell of claim 12, wherein, The thinning segments of the thinning region are two.

14. The battery cell of claim 1, wherein, In a projection plane perpendicular to the thickness direction of the wall portion, the orthographic projection of the thinning region extends along a straight line trajectory.

15. The battery cell of any one of claims 1-14, wherein, In a projection plane perpendicular to the thickness direction of the wall portion, the position of the orthographic projection of the thinning region closest to the geometric center of the orthographic projection of the pressure relief portion is a first position, and the position of the orthographic projection of the thinning region farthest from the geometric center of the orthographic projection of the pressure relief portion is a second position; The minimum thickness of the thinning region at the first position is greater than the minimum thickness of the thinning region at the second position.

16. The battery cell of claim 15, wherein, The minimum thickness of the thinning region in the cross section gradually increases from the second position to the first position along the extension direction of the thinning region.

17. The battery cell of claim 15, wherein, Both ends of the thinning region in its extension direction are connected with the weak portion, and the thinning region comprises two first segments connected with each other, the connection position of the two first segments is the first position, and the position where the first segment is connected with the weak portion is the second position; The lengths of the two first segments are equal along the extension direction of the thinning region.

18. The battery cell of claim 1, wherein, The weak portion comprises a first weak segment and a second weak segment connected in sequence, and the minimum thickness of the second weak segment is greater than the minimum thickness of the first weak segment.

19. The battery cell of claim 18, wherein, The weak portion comprises two straight segments and two arc segments, the two straight segments are oppositely arranged along a first direction and extend along a second direction, the two arc segments are oppositely arranged along the second direction and extend along an arc trajectory, one straight segment, one arc segment, the other straight segment and the other arc segment are sequentially connected in sequence, and the first direction, the second direction and the thickness direction of the wall portion are perpendicular to each other; The first weak segment comprises two arc segments and one straight segment, and the second weak segment is the other straight segment.

20. The battery cell of claim 1, wherein, The minimum thickness of the weak portion is D1, and the minimum thickness of the thinning region is D2, and 0.18≤D1 / D2≤0.62 is satisfied.

21. The battery cell of claim 20, wherein, 0.02mm≤D1≤0.24mm; and / or 0.22mm≤D2≤0.38mm.

22. The battery cell of claim 1, wherein, At least part of the pressure relief portion is raised in a direction close to or away from the electrode assembly along a thickness direction of the wall portion and forms a raised portion, and the weakened portion is arranged outside the raised portion.

23. The battery cell of claim 22, wherein, The raised portion includes at least part of the thinned region.

24. The battery cell of claim 22, wherein, The pressure relief mechanism has opposite first and second surfaces along a thickness direction of the wall portion, the first surface is provided with a groove, a groove bottom wall of the groove includes the weakened portion, and part of the groove bottom wall is raised in a direction from the second surface to the first surface and forms the raised portion.

25. The battery cell of claim 24, wherein, The second surface is arranged to face the electrode assembly along the thickness direction of the wall portion.

26. The battery cell of claim 24, wherein, The pressure relief mechanism is provided with a pressure relief groove and forms the weakened portion, and in a projection plane perpendicular to the thickness direction of the wall portion, a normal projection of the weakened portion and a normal projection of a groove wall surface of the pressure relief groove overlap. The pressure relief groove is arranged on a groove bottom surface of the groove.

27. The battery cell of claim 1, wherein, The pressure relief mechanism is provided with a pressure relief groove and forms the weakened portion, and in a projection plane perpendicular to the thickness direction of the wall portion, a normal projection of the weakened portion and a normal projection of a groove wall surface of the pressure relief groove overlap.

28. The battery cell of claim 1, wherein, The pressure relief portion is provided with a thinned groove and forms the thinned region, and in a projection plane perpendicular to the thickness direction of the wall portion, a normal projection of the thinned region and a normal projection of a groove wall surface of the thinned groove overlap.

29. The battery cell of claim 1, wherein, The pressure relief mechanism is separately arranged from the wall portion; or The pressure relief mechanism is integrally formed with the wall portion.

30. The battery cell of claim 1, wherein, The housing includes: A housing including an integrally formed side wall and a bottom wall, the side wall being arranged around the bottom wall, one end of the side wall being connected to the bottom wall along a thickness direction of the wall portion, and the other end being closed to form an opening, the side wall and the bottom wall jointly defining a containing cavity, and the electrode assembly being contained in the containing cavity; An end cover closing the opening; The end cover is the wall portion; or The bottom wall is the wall portion.

31. A battery device, characterized by A battery cell as claimed in any one of claims 1 to 30.

32. An electrical device, comprising: A battery cell as claimed in any one of claims 1 to 30, the battery cell being used to provide electrical energy.

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