Cylindrical battery cell, battery device, and electric device

Abstract

This application provides a cylindrical battery cell, a battery device, and an electrical device, belonging to the field of battery technology. The cylindrical battery cell includes a casing, an electrode assembly, and a first current collector. A protrusion is provided on the inner wall surface of the sidewall of the casing. The body region of the first current collector is connected to the first tab of the electrode assembly. The first connecting region of the first current collector and the first connecting wall are arranged facing each other along a first direction and welded together to form a connecting portion. The protruding first connecting wall includes a main body region and a second connecting region arranged side-by-side along a second direction. A portion of the connecting portion is embedded within the second connecting region. The first grain proportion of the second connecting region is greater than 50%. The second connecting region intersects a preset plane at a first cross-section. Within the first cross-section, the longest of the multiple lines connecting any two points on the outer contour of the first grain is the first connecting line, which also includes the second connecting line. The second connecting line is perpendicular to the first connecting line and passes through the midpoint of the first connecting line. The ratio of the length of the first connecting line to the length of the second connecting line is 1 to 5.

Description

Cylindrical battery cells, battery packs and electrical devices Technical Field

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

[0002] In recent years, new energy vehicles have experienced rapid development. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also increasing. Among them, battery devices typically include a casing and multiple cylindrical battery cells housed within the casing.

[0003] In battery technology, a cylindrical battery cell includes a casing and an electrode assembly housed within the casing. The electrode assembly has tabs that are welded to a current collector, which in turn is welded to the casing. This allows the cylindrical battery cell to input or output electrical energy through the casing. However, in the prior art, cylindrical battery cells are prone to detachment of the current collector from the casing or the tabs during use, which can lead to connection failure between the electrode assembly and the casing. This is detrimental to improving the stability and lifespan of the cylindrical battery cell.

[0004] Summary of the Invention

[0005] This application provides a cylindrical battery cell, a battery device, and an electrical device, which can effectively improve the stability and service life of the cylindrical battery cell.

[0006] In a first aspect, embodiments of this application provide a cylindrical battery cell, including a housing, an electrode assembly, and a first current collector; the housing includes a first wall, a second wall, and a side wall, the first wall and the second wall being disposed opposite each other along the axial direction of the cylindrical battery cell, the side wall surrounding the first wall and the second wall, and the side wall connecting the first wall and the second wall at its two ends along the axial direction of the cylindrical battery cell, respectively; a protrusion is provided on the inner wall surface of the side wall, the protrusion including a first connecting wall; the electrode assembly is housed within the housing, the electrode assembly having a first electrode tab; the first current collector is disposed within the housing, the first electrode tab being electrically connected to the protrusion through the first current collector, the first current collector including a body region and a first connecting region, the body region being connected to the first electrode tab, the first connecting region and the first connecting wall being disposed facing each other along a first direction, and being welded to the first connecting wall to form a connecting portion, the first connecting wall including a first connecting region along a first direction. Two main body areas and a second connecting area are arranged side by side in two directions. A portion of the connecting part is embedded in the second connecting area, and the connecting part is connected to the main body area through the second connecting area. The first direction is parallel to the thickness direction of the first connecting wall, and the first direction is perpendicular to the second direction. At least some of the grains in the second connecting area are first grains, and the ratio of the number of first grains to the total number of grains in the second connecting area is greater than 50%. The second connecting area intersects with a preset plane to form a first cross section. The preset plane is parallel to the first direction and the second direction. In the first cross section, the longest line among multiple lines connecting any two points on the outer contour of the first grain is the first connecting line. The multiple lines connecting any two points on the outer contour of the first grain also include a second connecting line. The second connecting line is perpendicular to the first connecting line and passes through the midpoint of the first connecting line. The ratio of the length of the first connecting line to the length of the second connecting line is in the range of 1 to 5.

[0007] In the above technical solution, a first current collector is provided inside the casing. The body area of ​​the first current collector is connected to the first tab of the electrode assembly, and the first connecting area of ​​the first current collector is welded to the raised first connecting wall to enable the cylindrical battery cell to input or output electrical energy through the side wall of the casing. The raised first connecting wall includes a body area and a second connecting area arranged side by side along a second direction. A portion of the connection formed by welding the first connecting area and the first connecting wall is embedded in and connected to the second connecting area, so that the first connecting area of ​​the first current collector is a structure that is welded to the second connecting area to form a connection. By setting the ratio of the length of the first connecting line and the length of the second connecting line in the first cross section of the first grain to 1 to 5, the size difference of the outer contour of the first grain is small. The cylindrical battery cell has equiaxed grains, and the proportion of the first grains in the second connection area is greater than 50%, resulting in a higher proportion of equiaxed grains in the second connection area. This reduces the constraint force between the grains in the second connection area, giving it better toughness and making it easier to deform. When the first current collector and sidewall are pulled due to the shaking of the electrode assembly during use, the second connection area can play a certain buffering role between the connection part and the main body area. This can effectively alleviate the rigid pulling between the first current collector and the protrusion, which helps to reduce the phenomenon of weld detachment of the first current collector and the protrusion during use. In addition, it can reduce the risk of connection failure between the electrode assembly and the sidewall of the shell, thereby improving the stability and service life of the cylindrical battery cell.

[0008] In some embodiments, the ratio of the length of the first connecting line to the length of the second connecting line ranges from 1 to 3.

[0009] In the above technical solution, by further setting the ratio of the length of the first connecting line and the length of the second connecting line in the first cross section of the first grain to 1 to 3, the dimensional difference of the outer contour of the first grain is further reduced, which is beneficial to further improve the shape regularity of the first grain. This can further reduce the constraint force between grains in the second connection area, thereby further improving the toughness of the second connection area. This is beneficial to further improve the buffering effect of the second connection area between the connection part and the main body area, and further reduce the rigid tension between the first current collector and the protrusion, thereby further alleviating the phenomenon of weld detachment between the first current collector and the protrusion.

[0010] In some embodiments, the lengths of the first connecting line and the second connecting line are both 5 μm to 200 μm.

[0011] In the above technical solution, by setting the length of the first connection line and the length of the second connection line within the first cross section of the first grain to be between 5μm and 200μm, the difference in the volume and outer contour of the first grain is small, which is beneficial to further reduce the constraint force between grains in the second connection area, so that the second connection area has better toughness, thereby further improving the buffering effect of the second connection area between the connection part and the main body area, so as to reduce the rigid tension between the first current collector and the protrusion.

[0012] In some embodiments, at least some of the grains in the main body region are second grains, the ratio of the number of second grains to the total number of grains in the main body region is greater than 50%, the main body region intersects with the preset plane to form a second cross section, in the second cross section, the longest line among the multiple lines connecting any two points on the outer contour of the second grain is the third line, and the multiple lines connecting any two points on the outer contour of the second grain also include a fourth line, the fourth line is perpendicular to the third line and passes through the midpoint of the third line, and the ratio of the length of the third line to the length of the fourth line is in the range of 5 to 100.

[0013] In the above technical solution, by setting the ratio of the length of the third connecting line and the length of the fourth connecting line of the second grain in the second cross section to 5 to 100, the second grain is a banded grain with a large difference in the size of its outer contour. The proportion of the second grain in the main body is greater than or equal to 50%, which makes the proportion of banded grains in the main body more. This results in a greater constraint force between the grains in the main body, which is beneficial to improving the strength and deformation resistance of the main body. In turn, it can reduce the risk of cracking or damage to the protruding main body during use.

[0014] In some embodiments, the length of the third connection is 150μm to 1000μm; the length of the fourth connection is 5μm to 120μm.

[0015] In the above technical solution, by setting the length of the third connection line of the second grain in the second cross section to 150μm to 1000μm, and setting the length of the fourth connection line of the second grain in the second cross section to 5μm to 120μm, the second grain is made into a strip-shaped grain with a large difference in the size of its outer contour. This not only improves the strength and deformation resistance of the main body area, but also alleviates the phenomenon of excessive size difference in the outer contour of the second grain, thereby reducing the forming difficulty of the second grain in the main body area and effectively reducing the manufacturing cost of the cylindrical battery cell.

[0016] In some embodiments, the angle between the extension direction of the third line and the second direction is 0° to 30°.

[0017] In the above technical solution, by setting the extension direction of the third connecting line of the second grain in the second cross section of the main body region to an angle of 0 to 30 degrees with the second direction, the length direction of the second grain is approximately the second direction, so that the length direction of the second grain can be consistent with the arrangement direction of the main body region and the second connecting region. This reduces the molding difficulty of the second grain in the main body region, thereby reducing the manufacturing difficulty of the protrusion. On the other hand, it further improves the strength and deformation resistance of the main body region, thereby further reducing the risk of cracking or damage to the main body region of the protrusion during use.

[0018] In some embodiments, the length of the third connection is greater than the length of the first connection.

[0019] In the above technical solution, by setting the length of the third connection line of the second grain in the second cross section to be greater than the length of the first connection line of the first grain in the first cross section of the second connecting region, the space occupied by the first grain is smaller than the space occupied by the second grain. This makes the number of first grains in the second connecting region per unit area greater than the number of second grains in the main region per unit area. As a result, the grain size of the second connecting region is higher than that of the main region, so that the second connecting region has better plasticity and toughness than the main region. This makes the second connecting region more prone to deformation, which is beneficial to improving the buffering effect of the second connecting region between the connecting part and the main region, thereby reducing the rigid tension between the first current collector and the protrusion.

[0020] In some embodiments, the ratio of the length of the third connection to the length of the first connection ranges from 1.5 to 150.

[0021] In the above technical solution, by setting the length of the third connection line of the second grain in the second cross section of the main body region to 1.5 to 150 times the length of the first connection line of the first grain in the first cross section of the second connecting region, on the one hand, the space occupied by the first grain can be further reduced to the space occupied by the second grain, so that the number of first grains in the second connecting region per unit area is greater than the number of second grains in the main body region per unit area. This can further improve the grain size of the second connecting region, so that the second connecting region has better plasticity and toughness than the main body region. In addition, while improving the toughness of the second connecting region, it can also improve the strength and deformation resistance of the main body region. This allows the second connecting region to play a better buffering role between the connecting part and the main body region, while also improving the overall structural strength of the main body region, thereby reducing the risk of large-area deformation of the protruding first connecting wall during use. On the other hand, it can alleviate the phenomenon of excessive size difference between the second grain in the main body region and the first grain in the second connecting region, which is conducive to reducing the molding difficulty of the second grain in the main body region and the first grain in the second connecting region, thereby reducing the manufacturing difficulty of the protrusion.

[0022] In some embodiments, the ratio of the length of the third connection to the length of the first connection ranges from 1.8 to 100.

[0023] In the above technical solution, by further setting the length of the third connection line of the second grain in the second cross section of the main body region to 1.8 to 100 times the length of the first connection line of the first grain in the first cross section of the second connecting region, on the one hand, the space occupied by the first grain can be further reduced to the space occupied by the second grain, so that the number of first grains in the second connecting region per unit area is greater than the number of second grains in the main body region per unit area. This can further improve the grain size of the second connecting region, so that the second connecting region has better plasticity and toughness than the main body region. In addition, while improving the toughness of the second connecting region, it can also further improve the strength and deformation resistance of the main body region. This allows the second connecting region to play a better buffering role between the connecting part and the main body region, while also further improving the overall structural strength of the main body region, so as to further reduce the risk of large-area deformation of the protruding first connecting wall during use. On the other hand, it can further alleviate the phenomenon of excessive size difference between the second grain in the main body region and the first grain in the second connecting region, which is conducive to further reducing the molding difficulty of the second grain in the main body region and the first grain in the second connecting region, so as to further reduce the manufacturing difficulty of the protrusion.

[0024] In some embodiments, along the second direction, the maximum size of the second grain is greater than the maximum size of the first grain.

[0025] In the above technical solution, by setting the maximum size of the second grain in the main body region in the second direction to be greater than the maximum size of the first grain in the second connection region in the second direction, the grains in the main body region have a greater ability to restrain each other in the first direction than the grains in the second connection region. As a result, when the first connection region pulls the first connecting wall of the protrusion along the first direction, the second connection region has better plasticity and toughness than the main body region. This makes the second connection region more prone to deformation, which is beneficial to further improve the buffering effect of the second connection region between the connection part and the main body region. This further reduces the rigid pulling between the first current collector and the protrusion, and further reduces the phenomenon of weld detachment of the first current collector and the protrusion during use. This further reduces the risk of connection failure between the electrode assembly and the side wall of the shell, thereby further improving the stability and service life of the cylindrical battery cell.

[0026] In some embodiments, the Vickers hardness of the second connection region is less than that of the body region.

[0027] In the above technical solution, by setting the hardness of the second connection area to be less than that of the main body area, when the first connection area of ​​the first current collector is pulled and protruded due to the shaking of the electrode assembly during the use of the cylindrical battery cell, the second connection area can play a certain buffering role between the connection part and the main body area. This can alleviate the rigid pulling between the first connection area of ​​the first current collector and the protrusion, which helps to reduce the phenomenon of weld detachment between the first connection area of ​​the first current collector and the protrusion. In turn, it can reduce the risk of connection failure between the electrode assembly and the side wall of the shell during the use of the cylindrical battery cell, thereby improving the stability and service life of the cylindrical battery cell.

[0028] In some embodiments, the ratio of the Vickers hardness of the second connection region to the Vickers hardness of the main body region is 0.3 to 0.8.

[0029] In the above technical solution, by setting the ratio of the Vickers hardness of the second connecting area to the Vickers hardness of the main body area to 0.3 to 0.8, the buffering effect of the second connecting area between the main body area and the connecting part is improved, while the structural strength and deformation resistance of the main body area are further improved. This helps to alleviate the cracking phenomenon in the main body area during use and reduces the risk of large-area deformation of the protruding first connecting wall during use.

[0030] In some embodiments, the ratio of the Vickers hardness of the second connection region to the Vickers hardness of the main body region is 0.5 to 0.8.

[0031] In the above technical solution, by further setting the ratio of the Vickers hardness of the second connecting area to the Vickers hardness of the main body area to 0.5 to 0.8, the buffering effect of the second connecting area between the main body area and the connecting part is improved, while the structural strength and deformation resistance of the main body area are also further improved. This helps to further alleviate the phenomenon of cracking in the main body area during use, and can further reduce the risk of large-area deformation of the protruding first connecting wall during use.

[0032] In some embodiments, the Vickers hardness value of the second connection region is 50 to 160.

[0033] In the above technical solution, the Vickers hardness of the second connection area is 50 to 160. On the one hand, by setting the Vickers hardness of the second connection area to be greater than or equal to 50, the structural strength of the second connection area is improved, which helps to alleviate the phenomenon of cracking or damage that occurs when the second connection area and the first connection area of ​​the first current collector are assembled or used, thereby improving the stability of the cylindrical battery cell. On the other hand, by setting the Vickers hardness of the second connection area to be less than or equal to 160, the buffering effect between the second connection area and the main body area is improved, which further alleviates the rigid tension between the first connection area and the protrusion of the first current collector, thereby further reducing the phenomenon of weld detachment between the first connection area and the protrusion of the first current collector.

[0034] In some embodiments, the Vickers hardness value of the main body region is 70 to 200.

[0035] In the above technical solution, the Vickers hardness of the main body area is 70 to 200. On the one hand, by setting the Vickers hardness of the main body area to be greater than or equal to 70, the overall structural strength of the protrusion is improved, which helps to alleviate the phenomenon of cracking or damage during use, thereby improving the stability of the cylindrical battery cell. On the other hand, by setting the Vickers hardness of the main body area to be less than or equal to 200, the forming difficulty and processing difficulty of the protrusion are reduced, and the manufacturing cost of the cylindrical battery cell is reduced.

[0036] In some embodiments, the second connection area includes two first sub-connection areas, which are located on both sides of the connection portion in the width direction of the connection portion.

[0037] In the above technical solution, the second connection area has two first sub-connection areas located on both sides of the connection part in the width direction of the connection part, so that each side of the connection part is connected to the main body area through a first sub-connection area. This allows the second connection area to play a certain buffering role on both sides of the connection part, which helps to further alleviate the rigid tension between the first connection area of ​​the first current collector and the protrusion, thereby further reducing the phenomenon of weld detachment between the first connection area of ​​the first current collector and the protrusion, and further reducing the risk of connection failure between the electrode assembly and the side wall of the shell.

[0038] In some embodiments, the first connecting region and the second connecting region are stacked along the first direction, and the connecting portion connects the first connecting region and the second connecting region; wherein, along the first direction, the second connecting region has a first surface facing the first connecting region, and the minimum distance between the orthographic projection of the portion of the connecting portion embedded in the second connecting region and the outer edge of the first surface is L1, satisfying 0.05mm≤L1≤2.5mm.

[0039] In the above technical solution, the minimum distance between the orthographic projection of the portion of the connecting part embedded in the second connecting area onto the first surface and the outer edge of the first surface is 0.05mm to 2.5mm. This makes the minimum dimension of the second connecting area between the connecting part and the main body area 0.05mm to 2.5mm. On the one hand, by setting the minimum distance between the orthographic projection of the portion of the connecting part embedded in the second connecting area onto the first surface and the outer edge of the first surface to be greater than or equal to 0.05mm, the size of the buffer area between the connecting part and the main body area can be increased, which is beneficial to improving the buffering effect of the second connecting area between the connecting part and the main body area. This can further alleviate the rigid tension between the first connecting area and the protrusion of the first current collector, thereby further reducing the phenomenon of weld detachment between the first connecting area and the protrusion of the first current collector. On the other hand, by setting the minimum distance between the orthographic projection of the part of the connecting part embedded in the second connecting area in the first surface and the outer edge of the first surface to be less than or equal to 2.5mm, the phenomenon of weakening the overall structural strength of the first connecting wall of the protrusion due to excessive space occupied by the second connecting area can be alleviated. Thus, while realizing the buffering effect of the second connecting area between the connecting part and the main body area, the overall structural strength of the protrusion can also be improved.

[0040] In some embodiments, the sidewall is formed with a groove on the side opposite to the electrode assembly and corresponding to the position of the protrusion. The protrusion includes two first connecting walls and a second connecting wall. The two first connecting walls are arranged opposite to each other along the first direction. The groove is formed between the two first connecting walls. The two ends of the second connecting wall in the first direction are respectively connected to the two first connecting walls. In this embodiment, one of the two first connecting walls is welded to the first connecting area to form the connecting portion.

[0041] In the above technical solution, by forming a groove on the side of the sidewall facing away from the electrode assembly and corresponding to the protrusion, the protrusion formed on the side of the sidewall facing the electrode assembly can be formed by stamping. This allows for the formation of a protrusion on the side of the sidewall facing the electrode assembly and a groove on the other side corresponding to the protrusion. Cylindrical battery cells with this structure can reduce the difficulty of forming a protrusion on the side of the sidewall facing the electrode assembly, which is beneficial to improving the production efficiency of cylindrical battery cells. On the other hand, it can make the interior of the protrusion hollow, thereby reducing the power required for welding the first connecting wall of the protrusion and the first connecting area of ​​the first current collector to each other, which is beneficial to reducing the welding difficulty between the first connecting wall of the protrusion and the first connecting area of ​​the first current collector. Furthermore, it allows the protrusion to have the ability to deform elastically, which is beneficial to further alleviate the rigid tension between the first connecting area of ​​the first current collector and the protrusion, thereby reducing the risk of weld detachment between the first connecting area of ​​the first current collector and the protrusion.

[0042] In some embodiments, the wall thickness of the protruding portion is less than the wall thickness of the other portions of the protrusion.

[0043] In the above technical solution, by setting the wall thickness of the protruding part to be less than the wall thickness of the other parts of the protrusion, the groove wall of the groove is locally thinned and forms a thinned area, thereby improving the elastic deformation capability of the protrusion. This helps to further alleviate the rigid tension between the first connecting area of ​​the first current collector and the protrusion, thereby reducing the risk of weld detachment between the first connecting area of ​​the first current collector and the protrusion.

[0044] In some embodiments, at least a portion of the wall thickness of the protrusion is less than the wall thickness of the sidewall.

[0045] In the above technical solution, by setting the wall thickness of at least a portion of the protrusion to be less than the wall thickness of the sidewall, the structural strength of the sidewall can be improved while the elastic deformation capability of the protrusion can be enhanced, so as to further alleviate the rigid tension between the first connection area of ​​the first current collector and the protrusion, thereby reducing the risk of weld detachment between the first connection area of ​​the first current collector and the protrusion.

[0046] In some embodiments, the protrusion is an annular structure extending circumferentially along the sidewall, and the first connecting wall is an annular structure extending circumferentially along the sidewall.

[0047] In the above technical solution, by setting the protrusion as a ring structure extending circumferentially along the sidewall, the first connecting wall of the protrusion is also a ring structure extending circumferentially along the sidewall. This allows the first connecting wall of the protrusion to be welded to the first connecting area of ​​the first current collector at any position in the circumferential direction of the sidewall. This facilitates the welding connection between the first connecting area of ​​the first current collector and the first connecting wall of the protrusion. After the first current collector is assembled into the housing, there is no need to rotate or adjust the position of the first current collector to achieve the welding assembly of the first connecting area and the first connecting wall of the protrusion. This further reduces the welding difficulty between the first connecting area of ​​the first current collector and the first connecting wall of the protrusion, thereby effectively improving the assembly efficiency of the cylindrical battery cell.

[0048] In some embodiments, the connecting portion extends circumferentially along the sidewall.

[0049] In the above technical solution, by setting the connecting part to be consistent with the extension direction of the first connecting wall of the protrusion, the area of ​​the first connecting area of ​​the first current collector and the first connecting wall can be increased, and the first connecting wall of the protrusion can be welded to the first connecting area of ​​the first current collector at multiple positions in the circumferential direction of the side wall. On the one hand, it can further improve the connection stability and reliability between the first connecting area of ​​the first current collector and the protrusion, so as to reduce the risk of weld detachment between the first connecting area of ​​the first current collector and the protrusion during use. On the other hand, it can improve the flow area and flow balance between the first current collector and the protrusion, so as to reduce the risk of local temperature rise of the protrusion.

[0050] In some embodiments, the first connecting wall is formed with a plurality of second connecting regions, which are arranged at circumferential intervals along the sidewall, and each second connecting region is connected to a connecting portion.

[0051] In the above technical solution, a plurality of second connection areas are formed on the protrusion at circumferential intervals along the sidewall, and each second connection area is connected to a corresponding connection part, so that the first connection area of ​​the first current collector and the first connection wall of the protrusion are welded together to form a plurality of connection parts at circumferential intervals along the sidewall, and each connection part is connected to the main body area through a second connection area. This can further improve the connection stability and reliability between the first connection area of ​​the first current collector and the protrusion, which is conducive to further alleviating the phenomenon of weld detachment between the first connection area of ​​the first current collector and the protrusion. On the other hand, it can further increase the flow area between the first connection area of ​​the first current collector and the protrusion, so as to further improve the flow capacity between the first current collector and the protrusion.

[0052] In some embodiments, the electrode assembly further includes a body portion along the axial direction of the cylindrical battery cell, the body portion being located on the side of the protrusion facing away from the first wall, the first tab being connected to the end of the body portion facing the first wall, and the body region being located between the electrode assembly and the protrusion.

[0053] In the above technical solution, the main body of the electrode assembly is located on the side of the protrusion away from the first wall along the axial direction of the cylindrical battery cell, and the body area is located between the electrode assembly and the protrusion. This allows the body area of ​​the first current collector to provide a certain support for the main body of the electrode assembly and resist the expansion of the electrode assembly during use. By setting the first tab to be connected to the end of the main body facing the first wall and setting the body area of ​​the first current collector on the side of the first tab away from the main body, the main body, the first tab, and the body area are arranged sequentially along the axial direction of the cylindrical battery cell. This reduces the assembly difficulty between the first tab and the body area of ​​the first current collector, which is beneficial to improving the production efficiency of the cylindrical battery cell and optimizing the production process of the cylindrical battery cell.

[0054] In some embodiments, the first connection region is located on the side of the body region facing the first wall in the axial direction of the cylindrical battery cell; wherein the first current collector further includes a transition region connecting the body region and the first connection region, the transition region being configured to deform when the body region and the first connection region move closer or further apart from each other in the axial direction of the cylindrical battery cell.

[0055] In the above technical solution, the first current collector is also provided with a transition area connecting the body area and the first connection area. By setting the transition area as a structure that can deform when the body area and the first connection area move closer or further apart along the axial direction of the cylindrical battery cell, the transition area can play a certain buffering role between the body area and the first connection area. In this way, when the electrode assembly shakes or shifts, it can alleviate the rigid tension between the body area and the first connection area, between the body area and the first tab, and between the first connection area and the protrusion. This is beneficial to further reduce the risk of connection failure between the body area and the first tab and between the first connection area and the protrusion, and also helps to reduce the phenomenon of the first current collector being damaged by tension.

[0056] In some embodiments, the transition region is bent to form a plurality of bent segments, which are connected sequentially, and the bent segments located at both ends of the plurality of bent segments are respectively connected to the body region and the first connection region.

[0057] In the above technical solution, by setting the transition zone as a structure of multiple bent segments connected in sequence, and the bent segments at both ends of the multiple bent segments being connected to the body region and the first connecting region respectively, the deformation capacity of the transition zone can be increased when the body region and the first connecting region move closer or further away from each other along the axial direction of the cylindrical battery cell. This further enhances the buffering effect of the transition zone between the body region and the first connecting region, thereby further reducing the phenomenon of rigid tension between the body region and the first connecting region, between the body region and the first tab, and between the first connecting region and the protrusion.

[0058] In some embodiments, a pressure relief component is provided on the first wall, the pressure relief component being configured to release the internal pressure of the cylindrical battery cell.

[0059] In the above technical solution, by setting a pressure relief component on the first wall to release the internal pressure of the cylindrical battery cell, the cylindrical battery cell can still be depressurized through the pressure relief component when thermal runaway occurs, which helps to reduce the risk of explosion of the cylindrical battery cell during use and improve the reliability of the cylindrical battery cell.

[0060] In some embodiments, in a projection plane perpendicular to the axial direction of the cylindrical battery cell, the orthographic projection of the body region and the orthographic projection of the first connection region form an exhaust gap in the radial direction of the cylindrical battery cell.

[0061] In the above technical solution, in the projection plane perpendicular to the axis of the cylindrical battery cell, by setting the orthographic projection of the first connection area and the orthographic projection of the body area to form an exhaust gap in the radial direction of the cylindrical battery cell, the thermal runaway gas inside the cylindrical battery cell can enter the side of the first current collector facing the first wall through the exhaust gap between the first connection area and the body area and then be released through the pressure relief component. This helps to reduce the obstruction of the exhaust path inside the cylindrical battery cell by the first current collector, thereby improving the smoothness of the internal exhaust and the pressure relief rate of the cylindrical battery cell.

[0062] In some embodiments, the pressure relief component is provided with a pressure relief groove, at least a portion of which is projected onto the cylindrical battery cell along its axial direction within the venting gap.

[0063] In the above technical solution, by setting the pressure relief groove on the pressure relief component to a structure in which at least a portion of its projection on the axial direction of the cylindrical battery cell is located within the exhaust gap, the pressure relief groove is a structure in which at least a portion on the axial direction of the cylindrical battery cell corresponds to the exhaust gap between the first connection area and the body area. This can further improve the smoothness of internal exhaust and pressure relief of the cylindrical battery cell, thereby increasing the pressure relief rate of the cylindrical battery cell and reducing the risk of fire and explosion caused by untimely pressure relief of the cylindrical battery cell, thus improving the reliability of the cylindrical battery cell.

[0064] In some embodiments, in a projection plane perpendicular to the axial direction of the cylindrical battery cell, the orthographic projection of the first connection area extends circumferentially along the sidewall and is located on the periphery of the orthographic projection of the body area, and the orthographic projections of the first connection area and the body area are arranged radially spaced apart in the cylindrical battery cell. The diameter of the orthographic projection of the outer edge of the first connection area is d, and the orthographic projection of the transition area extends radially along the cylindrical battery cell with a length of L2, satisfying 1 / 15≤L2 / d≤1 / 3.

[0065] In the above technical solution, in the projection plane perpendicular to the axis of the cylindrical battery cell, by setting the orthographic projection of the first connection area and the orthographic projection of the body area to be arranged at intervals in the radial direction of the cylindrical battery cell, and setting the ratio of the length of the transition area of ​​the first current collector in the radial direction of the cylindrical battery cell to the diameter of the orthographic projection of the outer edge of the first connection area to 1 / 15 to 1 / 3, it can alleviate the phenomenon that the size occupied by the transition area in the radial direction of the cylindrical battery cell is too small, and is conducive to expanding the exhaust space between the first connection area and the body area, so that the thermal runaway gas inside the cylindrical battery cell can pass through the exhaust space between the first connection area and the body area and then through the first... The pressure relief components on the wall release pressure, thereby improving the internal venting smoothness of the cylindrical battery cell and increasing the pressure relief rate of the cylindrical battery cell. This reduces the risk of the cylindrical battery cell bursting or exploding due to untimely pressure relief. On the other hand, it can alleviate the phenomenon that the transition zone occupies too large a size in the radial direction of the cylindrical battery cell, resulting in insufficient support strength between the transition zone and the first connection zone. This can effectively improve the support effect of the first current collector on the electrode assembly and the effect of resisting the expansion of the electrode assembly during use, thereby alleviating the phenomenon of excessive expansion or displacement of the electrode assembly. This is conducive to improving the stability and reliability of the cylindrical battery cell in use.

[0066] In some embodiments, 1 / 7 ≤ L2 / d ≤ 1 / 4.

[0067] In the above technical solution, in the projection plane perpendicular to the axis of the cylindrical battery cell, by further setting the ratio of the length of the transition zone of the first current collector in the radial direction of the cylindrical battery cell to the diameter of the orthographic projection of the outer edge of the first connecting zone to 1 / 7 to 1 / 4, the problem of the transition zone occupying too small a size in the radial direction of the cylindrical battery cell can be further alleviated. This is beneficial to further expand the exhaust space between the first connecting zone and the body zone, so that the thermal runaway gas inside the cylindrical battery cell can be released through the exhaust space between the first connecting zone and the body zone and then through the pressure relief component on the first wall, thereby further improving the efficiency of the cylindrical battery cell. The smooth internal venting of the body further improves the depressurization rate of the cylindrical battery cell, thereby reducing the risk of bursting or exploding due to untimely depressurization. On the other hand, it can further alleviate the phenomenon that the transition zone occupies too large a size in the radial direction of the cylindrical battery cell, resulting in insufficient support strength between the body area and the first connection area. This can further improve the support effect of the first current collector on the electrode assembly and the effect of resisting the expansion of the electrode assembly during use, thereby further alleviating the phenomenon of excessive expansion or displacement of the electrode assembly, and thus helping to further improve the stability and reliability of the cylindrical battery cell.

[0068] In some embodiments, 3mm ≤ L2 ≤ 15mm.

[0069] In the above technical solution, in the projection plane perpendicular to the axis of the cylindrical battery cell, by setting the length of the transition zone of the first current collector in the radial direction of the cylindrical battery cell to 3mm to 15mm, on the one hand, setting the length of the transition zone in the radial direction of the cylindrical battery cell to be greater than or equal to 3mm can increase the exhaust space between the first connection area and the body area, so that the thermal runaway gas inside the cylindrical battery cell can be released through the exhaust space between the first connection area and the body area and then through the pressure relief component on the first wall, which is beneficial to improving the internal exhaust smoothness of the cylindrical battery cell. On the other hand, setting the length of the transition zone in the radial direction of the cylindrical battery cell to be less than or equal to 15mm can alleviate the phenomenon that the transition zone is too long and therefore the support strength between the body area and the first connection area is insufficient. This is beneficial to improving the support effect of the first current collector on the electrode assembly and the effect of resisting the expansion of the electrode assembly during use, so as to further alleviate the phenomenon of excessive expansion or displacement of the electrode assembly.

[0070] In some embodiments, the thickness of the transition region is T, and the width of the orthographic projection of the transition region in a projection plane perpendicular to the axial direction of the cylindrical battery cell, in a direction perpendicular to its extension direction, is W, satisfying 0.3 mm. 2 ≤W×T≤8mm 2 .

[0071] In the above technical solution, the product of W and T is set to 0.3mm. 2 up to 8mm 2 On the one hand, the product of W and T is set to be less than or equal to 8mm. 2 This design mitigates the problem of excessive deformation difficulty in the transition zone caused by excessively large W and T values. It enhances the transition zone's ability to deform when the body region and the first connecting region move closer or further apart along the axial direction of the cylindrical battery cell. This allows the transition zone to act as a better buffer between the body region and the first connecting region, reducing rigid tension between the body region and the first connecting region, between the body region and the first tab, and between the first connecting region and the protrusion during electrode assembly wobbling or displacement. Furthermore, setting the product of W and T to be greater than or equal to 0.3 mm... 2 It can improve the structural strength of the transition zone, which helps to alleviate the phenomenon of insufficient support strength between the body area and the first connection area, thereby improving the support effect of the first current collector on the electrode assembly and the effect of resisting the expansion of the electrode assembly during use. It can also improve the flow capacity of the transition zone, which helps to improve the flow guiding effect and flow guiding requirements of the first current collector.

[0072] In some embodiments, 2mm ≤ W ≤ 10mm.

[0073] In the above technical solution, by setting the width of the projection of the transition zone of the first current collector in the axial direction of the cylindrical battery cell to 2mm to 10mm, on the one hand, setting the width of the projection of the transition zone in the axial direction of the cylindrical battery cell to be greater than or equal to 2mm can improve the current carrying capacity of the transition zone, thereby improving the current guiding effect of the first current collector and improving the structural strength of the transition zone. This helps to alleviate the phenomenon of insufficient support strength of the transition zone between the body area and the first connection area, thereby improving the support effect of the first current collector on the electrode assembly and the effect of resisting the expansion of the electrode assembly during use. On the other hand, setting the width of the projection of the transition zone in the axial direction of the cylindrical battery cell to be less than or equal to 10mm can effectively improve the ability of the transition zone to deform when the body area and the first connection area move closer or further away from each other along the axial direction of the cylindrical battery cell. This allows the transition zone to play a better buffering role between the body area and the first connection area, thereby reducing the rigid pulling phenomenon between the body area and the first connection area, between the body area and the first tab, and between the first connection area and the protrusion when the electrode assembly shakes or shifts during use.

[0074] In some embodiments, 3mm ≤ W ≤ 5mm.

[0075] In the above technical solution, by further setting the width of the projection of the transition zone of the first current collector in the axial direction of the cylindrical battery cell to 3mm to 5mm, on the one hand, setting the width of the projection of the transition zone in the axial direction of the cylindrical battery cell to be greater than or equal to 3mm can further improve the current carrying capacity of the transition zone, thereby further improving the current guiding effect of the first current collector and further improving the structural strength of the transition zone. This helps to further alleviate the phenomenon of insufficient support strength of the transition zone between the body area and the first connection area, thereby further improving the support effect of the first current collector on the electrode assembly and the effect of resisting the expansion of the electrode assembly during use. On the other hand, setting the width of the projection of the transition zone in the axial direction of the cylindrical battery cell to be less than or equal to 5mm can further improve the ability of the transition zone to deform when the body area and the first connection area move closer or further away from each other along the axial direction of the cylindrical battery cell, thereby improving the buffering effect of the transition zone between the body area and the first connection area. This can further reduce the rigid pulling phenomenon between the body area and the first connection area, between the body area and the first tab, and between the first connection area and the protrusion when the electrode assembly shakes or shifts during use.

[0076] In some embodiments, 0.15mm ≤ T ≤ 0.8mm.

[0077] In the above technical solution, by setting the thickness of the transition zone of the first current collector to 0.15mm to 0.8mm, on the one hand, setting the thickness of the transition zone to be greater than or equal to 0.15mm can improve the current carrying capacity of the transition zone, thereby improving the current guiding effect of the first current collector and improving the structural strength of the transition zone. This helps to alleviate the phenomenon of insufficient support strength of the transition zone between the body area and the first connection area, thereby improving the support effect of the first current collector on the electrode assembly and the effect of resisting the expansion of the electrode assembly during use. On the other hand, setting the thickness of the transition zone to be less than or equal to 0.8mm can effectively improve the ability of the transition zone to deform when the body area and the first connection area move closer or further apart along the axial direction of the cylindrical battery cell. This allows the transition zone to play a better buffering role between the body area and the first connection area. In this way, when the electrode assembly shakes or shifts during use, it can reduce the rigid pulling phenomenon between the body area and the first connection area, between the body area and the first tab, and between the first connection area and the protrusion. It can also save the space occupied by the transition zone in the axial direction of the cylindrical battery cell, which is beneficial to improving the internal space utilization rate of the cylindrical battery cell.

[0078] In some embodiments, 0.3mm ≤ T ≤ 0.5mm.

[0079] In the above technical solution, by further setting the thickness of the transition zone of the first current collector to 0.3mm to 0.5mm, on the one hand, setting the thickness of the transition zone to greater than or equal to 0.3mm can further improve the current carrying capacity of the transition zone, thereby further improving the current guiding effect of the first current collector and further improving the structural strength of the transition zone. This helps to alleviate the phenomenon of insufficient support strength of the transition zone between the body area and the first connection area, thereby further improving the support effect of the first current collector on the electrode assembly and the effect of resisting the expansion of the electrode assembly during use. On the other hand, setting the thickness of the transition zone to less than or equal to 0.5mm can further improve the ability of the transition zone to deform when the body area and the first connection area move closer or further away from each other along the axial direction of the cylindrical battery cell, thereby further improving the buffering effect of the transition zone between the body area and the first connection area. This can further reduce the rigid pulling phenomenon between the body area and the first connection area, between the body area and the first tab, and between the first connection area and the protrusion when the electrode assembly shakes or shifts during use. It can also further save the space occupied by the transition zone in the axial direction of the cylindrical battery cell, which is conducive to further improving the internal space utilization rate of the cylindrical battery cell.

[0080] In some embodiments, the thickness of the transition region is less than the thickness of the body region; and / or, the thickness of the transition region is less than the thickness of the first connection region.

[0081] In the above technical solution, by setting the thickness of the transition region to be less than the thickness of the main body region, the manufacturing cost and difficulty of the first current collector are reduced, while the ability of the transition region to deform when the main body region and the first connecting region move closer or further apart along the axial direction of the cylindrical battery cell is improved. This allows the transition region to play a better buffering role between the main body region and the first connecting region. Similarly, by setting the thickness of the transition region to be less than the thickness of the first connecting region, the manufacturing cost and difficulty of the first current collector are reduced, while the ability of the transition region to deform when the main body region and the first connecting region move closer or further apart along the axial direction of the cylindrical battery cell is improved. This allows the transition region to play a better buffering role between the main body region and the first connecting region.

[0082] In some embodiments, the sidewall and the second wall are integrally formed, and the sidewall and the second wall enclose a receiving cavity, in which the electrode assembly is received; wherein, along the axial direction of the cylindrical battery cell, one end of the sidewall away from the second wall encloses an opening, and the first wall closes the opening.

[0083] In the above technical solution, by setting the sidewall of the outer casing to form an opening at the end of the cylindrical battery cell away from the second wall in the axial direction, and the first wall being a closed opening, the body area of ​​the first current collector is arranged on the side of the electrode assembly facing the opening in the axial direction of the cylindrical battery cell. This reduces the difficulty of assembling the body area of ​​the first current collector between the electrode assembly and the protrusion, and also reduces the welding difficulty between the first connection area of ​​the first current collector and the first connection wall of the protrusion. This reduces the assembly difficulty of the cylindrical battery cell, optimizes the manufacturing process of the cylindrical battery cell, and helps to improve the production efficiency of the cylindrical battery cell.

[0084] In some embodiments, along the axial direction of the cylindrical battery cell, the first connection area is located on the side of the protrusion facing the first wall, and the first connection area is welded to the side of the protrusion facing the first wall to form the connection portion.

[0085] In the above technical solution, by setting the first connection area of ​​the first current collector in the axial direction of the cylindrical battery cell to be located on the side of the protrusion facing the first wall and welded to the side of the protrusion facing the first wall, on the one hand, since the body area of ​​the first current collector is located between the electrode assembly and the protrusion, the first current collector and the protrusion can share part of the space in the axial direction of the cylindrical battery cell, which is beneficial to improving the internal space utilization of the cylindrical battery cell and thus improving the energy density of the cylindrical battery cell. On the other hand, by setting the first connection area of ​​the first current collector in the axial direction of the cylindrical battery cell to be located on the side of the protrusion facing the opening of the side wall and welded to the first connection wall of the protrusion, the first connection wall of the protrusion and the first connection area of ​​the first current collector can be welded and assembled from the opening of the side wall, which is beneficial to optimizing the production process of the cylindrical battery cell and reducing the assembly difficulty of the cylindrical battery cell.

[0086] In some embodiments, along the axial direction of the cylindrical battery cell, the first connection area is located on the side of the protrusion away from the first wall, and the first connection area is welded to the side of the protrusion away from the first wall to form the connection portion.

[0087] In the above technical solution, by setting the first connection area of ​​the first current collector to be located on the side of the protrusion away from the first wall in the axial direction of the cylindrical battery cell and welding it to the side of the protrusion away from the first wall, the first connection area of ​​the first current collector and the electrode assembly are both located on the side of the protrusion away from the first wall, which helps to reduce the assembly difficulty of the first current collector and the electrode assembly. In addition, the protrusion can also play a certain role in limiting and positioning the first current collector.

[0088] In some embodiments, the sidewall is bent at one end of the cylindrical battery cell away from the second wall in the axial direction to form a flange, the flange surrounding the opening; wherein, along the axial direction of the cylindrical battery cell, a portion of the first wall is located between the flange and the protrusion, the flange and the protrusion being configured to cooperate in clamping the first wall.

[0089] In the above technical solution, by bending the side wall away from the second wall along the axial direction of the cylindrical battery cell to form a flange, and setting the part of the first wall in the axial direction of the cylindrical battery cell between the protrusion and the flange, the protrusion and the flange can also play a role in assembling and fixing the first wall, so as to realize the assembly between the first wall and the side wall. The cylindrical battery cell with this structure can reduce the assembly difficulty between the first wall and the side wall, thereby improving the production efficiency of the cylindrical battery cell.

[0090] In some embodiments, the cylindrical battery cell further includes a seal; the seal is at least partially disposed radially between the sidewall and the first wall of the cylindrical battery cell, and the seal is configured to seal the gap between the first wall and the sidewall.

[0091] In the above technical solution, the cylindrical battery cell is also provided with a sealing element. By disposing at least a portion of the sealing element in the radial direction of the cylindrical battery cell between the side wall and the first wall, the sealing element can seal the gap between the first wall and the side wall, thereby reducing the risk of leakage during the use of the cylindrical battery cell and improving the stability and reliability of the cylindrical battery cell.

[0092] In some embodiments, the material of the first current collector includes copper.

[0093] In some embodiments, the first electrode tab is welded to the body region.

[0094] In the above technical solution, by setting the body area of ​​the first electrode and the first current collector to a welded connection, the reliability and robustness of the connection between the first electrode and the body area of ​​the first current collector are improved, thereby enhancing the stability of the cylindrical battery cell in use. Furthermore, the connection formed by welding the first connecting area of ​​the first current collector to the protruding first connecting wall is connected to the second connecting area. This allows the connecting area to be connected to the main body area via the second connecting area. During the use of the cylindrical battery cell, when the first electrode pulls on the first current collector due to the shaking of the electrode assembly, the second connecting area can act as a buffer between the connecting area and the main body area. This allows the first connecting area of ​​the first current collector to have the ability to float slightly relative to the protruding first connecting wall, thus mitigating rigid tension between the first electrode and the body area of ​​the first current collector. This helps reduce the phenomenon of weld detachment between the first electrode and the body area of ​​the first current collector, further reducing the risk of connection failure between the electrode assembly and the side wall of the casing during the use of the cylindrical battery cell, thereby improving the stability and service life of the cylindrical battery cell.

[0095] Secondly, embodiments of this application also provide a battery device, including the aforementioned cylindrical battery cell.

[0096] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned cylindrical battery cell, wherein the cylindrical battery cell is used to provide electrical energy. Attached Figure Description

[0097] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0098] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0099] Figure 2 is an exploded view of the structure of a battery device provided in some embodiments of this application;

[0100] Figure 3 is a schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of this application;

[0101] Figure 4 is an exploded view of the structure of a cylindrical battery cell provided in some embodiments of this application;

[0102] Figure 5 is a cross-sectional view of a cylindrical battery cell provided in some embodiments of this application;

[0103] Figure 6 is a partial enlarged view of point A of the cylindrical battery cell shown in Figure 5;

[0104] Figure 7 is a partial cross-sectional view of the side wall of the housing provided in some embodiments of this application;

[0105] Figure 8 is a cross-sectional view of the protruding first connecting wall in a preset plane provided in some embodiments of this application;

[0106] Figure 9 is a schematic diagram of the structure of the first current collector of a cylindrical battery cell provided in some embodiments of this application;

[0107] Figure 10 is a front view of the first current collector of a cylindrical battery cell provided in some embodiments of this application in the axial direction of the cylindrical battery cell;

[0108] Figure 11 is a cross-sectional view of a cylindrical battery cell provided in some embodiments of this application;

[0109] Figure 12 is a partial enlarged view of point B of the cylindrical battery cell shown in Figure 11.

[0110] Icons: 1000 - Vehicle; 100 - Battery assembly; 10 - Housing; 11 - First housing body; 12 - Second housing body; 20 - Cylindrical battery cell; 21 - Casing; 211 - First wall; 2111 - Pressure relief groove; 212 - Second wall; 2121 - Mounting hole; 213 - Side wall; 2131 - Opening; 2132 - Groove; 2133 - Flanged edge; 214 - Protrusion; 2141 - First connecting wall; 2141a - Main body area; 2141b - Second connecting area; 2141c - First grain; 2141d - First connecting line; 2141e - Second connecting line; 21 41f - Second grain; 2141g - Third connection line; 2141h - Fourth connection line; 2141k - First surface; 2142 - Second connecting wall; 22 - Electrode assembly; 221 - Main body; 222 - First tab; 223 - Second tab; 23 - First current collector; 231 - Body region; 232 - First connecting region; 233 - Transition region; 2331 - Bending section; 234 - Exhaust gap; 24 - Connecting part; 25 - Electrode terminal; 26 - Second current collector; 27 - Seal; 200 - Controller; 300 - Motor; X - First direction; Y - Second direction. Detailed Implementation

[0111] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0112] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0113] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0114] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0115] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0116] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0117] In this application, "multiple" means two or more (including two).

[0118] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0119] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0120] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0121] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0122] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0123] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0124] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds.

[0125] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0126] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0127] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0128] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0129] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0130] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0131] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0132] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0133] In some embodiments, the separator is a separator membrane. The separator membrane can be of various types, and any known porous separator membrane with good chemical and mechanical stability can be selected.

[0134] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0135] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0136] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0137] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0138] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0139] Among them, gel electrolytes include a polymer-based electrolyte backbone network combined with an ionic liquid-lithium salt.

[0140] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0141] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0142] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0143] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0144] In some implementations, the electrode assembly has a wound structure. The positive and negative electrode sheets are wound into a wound structure.

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

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

[0147] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0148] As an example, a single battery cell can be cylindrical, i.e., a cylindrical battery cell.

[0149] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0150] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0151] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0152] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0153] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0154] As an example, the enclosure may include a first enclosure body and a second enclosure body. The first enclosure body and the second enclosure body are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or shutting down; it can be sealed or not sealed. The first enclosure body may be a top cover or a bottom plate.

[0155] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0156] As an example, the housing can be part of the vehicle's chassis structure. For instance, the housing's roof can be at least part of the vehicle's floor, or the housing's frame can be at least part of the vehicle's crossbeams and longitudinal beams.

[0157] In some embodiments, the battery device refers to an energy storage device, which includes a housing with a door on at least one side. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0158] Battery devices possess outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide applicability, and low self-discharge coefficient, making them an important component of today's new energy development. The development of battery technology must simultaneously consider multiple design factors, such as performance parameters like energy density, cycle life, discharge capacity, and charge / discharge rate. Furthermore, the safety of the battery device must also be taken into account.

[0159] For a typical cylindrical battery cell, it usually includes a casing and an electrode assembly housed within the casing. The electrode assembly has tabs that are connected to one wall of the casing, allowing the cylindrical battery cell to input or output electrical energy through the casing. In related technologies, to reduce the assembly difficulty between the tabs and the casing, a current collector is usually installed inside the casing. The casing and the tabs are welded together through the current collector to achieve electrical connection between them. However, due to the complex operating conditions of cylindrical battery cells, the electrode assembly often experiences vibration or shaking within the casing. This structure of cylindrical battery cells is highly susceptible to rigid tension between the current collector and the casing, as well as between the current collector and the tabs, during use. This can lead to the risk of weld detachment between the current collector and the casing, resulting in connection failure between the electrode assembly and the casing during use. Consequently, this negatively impacts the stability and lifespan of the cylindrical battery cell.

[0160] Based on the above considerations, in order to solve the problems of low stability and short service life of cylindrical battery cells, this application provides a cylindrical battery cell, which includes a casing, an electrode assembly, and a first current collector. The casing includes a first wall, a second wall, and a side wall. The first wall and the second wall are arranged opposite each other along the axial direction of the cylindrical battery cell. The side wall surrounds the first wall and the second wall, and its two ends along the axial direction of the cylindrical battery cell are respectively connected to the first wall and the second wall. A protrusion is provided on the inner wall surface of the side wall, and the protrusion includes a first connecting wall. The electrode assembly is housed within the casing, and the electrode assembly has a first tab. The first current collector is disposed inside the housing. The first electrode is electrically connected to the protrusion through the first current collector. The first current collector includes a body area and a first connection area. The body area is connected to the first electrode. The first connection area and the first connection wall are arranged facing each other along a first direction and are welded together to form a connection part. The first connection wall includes a main body area and a second connection area arranged side by side along a second direction. A portion of the connection part is embedded in the second connection area, and the connection part is connected to the main body area through the second connection area. The first direction is parallel to the thickness direction of the first connection wall, and the first direction is perpendicular to the second direction. At least some of the grains in the second connecting region are first grains, and the ratio of the number of first grains to the total number of grains in the second connecting region is greater than 50%. The second connecting region intersects with a preset plane to form a first cross section. The preset plane is parallel to the first direction and the second direction. In the first cross section, the longest line among the multiple lines connecting any two points on the outer contour of the first grain is the first connecting line. The multiple lines connecting any two points on the outer contour of the first grain also include a second connecting line. The second connecting line is perpendicular to the first connecting line and passes through the midpoint of the first connecting line. The ratio of the length of the first connecting line to the length of the second connecting line is in the range of 1 to 5.

[0161] In this type of cylindrical battery cell, a first current collector is disposed inside the casing. The body region of the first current collector is connected to the first tab of the electrode assembly, and the first connecting region of the first current collector is welded to a raised first connecting wall. This allows the cylindrical battery cell to input or output electrical energy through the side wall of the casing. The raised first connecting wall includes a body region and a second connecting region arranged side by side along a second direction. A portion of the connection formed by welding the first connecting region and the first connecting wall is embedded in and connected to the second connecting region. This results in the first connecting region of the first current collector having a structure where it is welded to the second connecting region to form a connection. By setting the ratio of the length of the first connecting line and the length of the second connecting line within the first cross-section of the first grain to 1 to 5, the size difference of the outer contour of the first grain is achieved. The smaller equiaxed grains, with the first grains accounting for more than 50% of the second connection region, result in a higher proportion of equiaxed grains in the second connection region. This reduces the constraint force between the grains in the second connection region, giving it better toughness and making it easier to deform. When the first current collector and sidewalls are pulled due to the shaking of the electrode assembly during use, the second connection region can act as a buffer between the connection part and the main body area. This effectively alleviates the rigid pulling between the first current collector and the protrusion, reducing the likelihood of weld detachment during use. Consequently, it lowers the risk of connection failure between the electrode assembly and the sidewalls of the casing, thus improving the stability and lifespan of the cylindrical battery cell.

[0162] The cylindrical battery cells disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system for such an electrical device can be constructed using the cylindrical battery cells and battery assembly disclosed in this application. This helps to alleviate the problem of electrode assembly and casing connection failures during the use of cylindrical battery cells, thereby improving the stability and service life of the cylindrical battery cells.

[0163] This application provides an electrical device that uses a cylindrical battery cell or battery assembly as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0164] For ease of explanation, the following embodiments will be described using a vehicle as an example of an electrical device according to an embodiment of this application.

[0165] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside the vehicle 1000. The battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, it can serve as the vehicle's operating power source or general power source. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 controls the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0166] In some embodiments of this application, the battery device 100 can not only serve as the operating power or power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0167] Please refer to Figures 2 and 3. Figure 2 is an exploded view of the structure of a battery device 100 provided in some embodiments of this application, and Figure 3 is a schematic diagram of the structure of a cylindrical battery cell 20 provided in some embodiments of this application. The battery device 100 includes a housing 10 and a cylindrical battery cell 20, which is housed within the housing 10.

[0168] The housing 10 provides an assembly space for the cylindrical battery cell 20, and the housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, which overlap each other, and together define an assembly space for accommodating the cylindrical battery cell 20. The second housing body 12 may be a hollow structure with one end open, and the first housing body 11 may be a plate-like structure, with the first housing body 11 covering the open side of the second housing body 12 so that the first housing body 11 and the second housing body 12 together define the assembly space; alternatively, the first housing body 11 and the second housing body 12 may both be hollow structures with one side open, with the open side of the first housing body 11 covering the open side of the second housing body 12.

[0169] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder, a cuboid, or a cube. For example, in Figure 2, the shape of the box 10 is a cuboid.

[0170] In the battery device 100, there can be one or more cylindrical battery cells 20 disposed within the housing 10. When there are multiple cylindrical battery cells 20 disposed within the housing 10, the multiple cylindrical battery cells 20 can be connected in series, in parallel, or in a mixed manner. A mixed connection means that the multiple cylindrical battery cells 20 are connected in both series and parallel. The multiple cylindrical battery cells 20 can be directly connected in series, in parallel, or in a mixed manner, and then the whole assembly of the multiple cylindrical battery cells 20 is housed within the housing 10. Of course, the battery device 100 can also be in the form of multiple cylindrical battery cells 20 first connected in series, in parallel, or in a mixed manner to form a battery module, and then the multiple battery modules are connected in series, in parallel, or in a mixed manner to form a whole assembly, which is then housed within the housing 10.

[0171] In some embodiments, the battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar for connecting a plurality of cylindrical battery cells 20 to achieve electrical connection between the plurality of cylindrical battery cells 20.

[0172] Each cylindrical battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited to these.

[0173] According to some embodiments of this application, referring to Figure 3, and further referring to Figures 4, 5, 6, 7, and 8, Figure 4 is an exploded view of the cylindrical battery cell 20 provided in some embodiments of this application; Figure 5 is a cross-sectional view of the cylindrical battery cell 20 provided in some embodiments of this application; Figure 6 is a partial enlarged view of point A of the cylindrical battery cell 20 shown in Figure 5; Figure 7 is a partial cross-sectional view of the side wall 213 of the outer casing 21 provided in some embodiments of this application; and Figure 8 is a cross-sectional view of the first connecting wall 2141 of the protrusion 214 provided in some embodiments of this application in a predetermined plane. This application provides a cylindrical battery cell 20, which includes an outer casing 21, an electrode assembly 22, and a first current collector 23. The outer casing 21 includes a first wall 211, a second wall 212, and a side wall 213. The first wall 211 and the second wall 212 are arranged opposite each other along the axial direction of the cylindrical battery cell 20. The side wall 213 surrounds the first wall 211 and the second wall 212, and the two ends of the side wall 213 in the axial direction of the cylindrical battery cell 20 are respectively connected to the first wall 211 and the second wall 212. A protrusion 214 is provided on the inner wall surface of the side wall 213, and the protrusion 214 includes a first connecting wall 2141. The electrode assembly 22 is housed in the outer casing 21, and the electrode assembly 22 has a first tab 222. The first current collector 23 is disposed inside the housing 21. The first electrode 222 is electrically connected to the protrusion 214 through the first current collector 23. The first current collector 23 includes a body region 231 and a first connecting region 232. The body region 231 is connected to the first electrode 222. The first connecting region 232 and the first connecting wall 2141 are disposed along the first direction X and are welded together to form a connecting part 24. The first connecting wall 2141 includes a main body region 2141a and a second connecting region 2141b arranged side by side along the second direction Y. A portion of the connecting part 24 is embedded in the second connecting region 2141b, and the connecting part 24 is connected to the main body region 2141a through the second connecting region 2141b. The first direction X is parallel to the thickness direction of the first connecting wall 2141, and the first direction X is perpendicular to the second direction Y. At least some of the grains within the second connecting region 2141b are first grains 2141c. The ratio of the number of first grains 2141c to the total number of grains within the second connecting region 2141b is greater than 50%. The second connecting region 2141b intersects with a preset plane to form a first cross section. The preset plane is parallel to the first direction X and the second direction Y. Within the first cross section, the longest line among the multiple lines connecting any two points on the outer contour of the first grain 2141c is the first connecting line 2141d. The multiple lines connecting any two points on the outer contour of the first grain 2141c also include a second connecting line 2141e. The second connecting line 2141e is perpendicular to the first connecting line 2141d and passes through the midpoint of the first connecting line 2141d. The ratio of the length of the first connecting line 2141d to the length of the second connecting line 2141e ranges from 1 to 5.

[0174] The outer shell 21 can also be used to contain electrolytes, such as electrolyte solutions. The outer shell 21 can have various structural forms. The outer shell 21 can also be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0175] In this embodiment of the application, the outer casing 21 includes a first wall 211, a second wall 212 and a side wall 213. The side wall 213 is a structure surrounding the first wall 211 and the second wall 212. The first wall 211 and the second wall 212 are arranged opposite to each other along the axial direction of the cylindrical battery cell 20, such that the first wall 211 and the second wall 212 are the end walls of the outer casing 21 at both ends of the cylindrical battery cell 20 in the axial direction.

[0176] Optionally, the structure of the outer casing 21 can be varied. For example, the outer casing 21 can be integrally formed with the first wall 211 and the side wall 213, with the side wall 213 forming an opening 2131 at one end of the cylindrical battery cell 20 away from the first wall 211 in the axial direction, and the second wall 212 covering the opening 2131 of the side wall 213 to form a sealed connection, thereby forming a sealed space for accommodating the electrode assembly 22 and the electrolyte; the outer casing 21 can also be integrally formed with the second wall 212 and the side wall 213, with the side wall 213 at one end of the cylindrical battery cell 20 away from the second wall 212 in the axial direction. The end enclosure forms an opening 2131, and the first wall 211 covers the opening 2131 of the side wall 213 and forms a sealed connection to form a sealed space for accommodating the electrode assembly 22 and the electrolyte; the outer shell 21 may also have openings 2131 formed at both ends of the side wall 213 in the axial direction of the cylindrical battery cell 20, so that the side wall 213 is a hollow structure with openings 2131 formed at both ends of the cylindrical battery cell 20 in the axial direction, and the first wall 211 and the second wall 212 respectively cover the openings 2131 at both ends of the side wall 213 in the axial direction of the cylindrical battery cell 20.

[0177] For example, in Figures 4, 5 and 6, the second wall 212 and the side wall 213 are integrally formed, and the side wall 213 forms an opening 2131 at the end of the cylindrical battery cell 20 away from the second wall 212 in the axial direction. The first wall 211 covers the opening 2131 of the side wall 213 and forms a sealed connection to form a sealed space for accommodating the electrode assembly 22 and the electrolyte. The electrode assembly 22 is located on the side of the protrusion 214 away from the first wall 211 in the axial direction of the cylindrical battery cell 20, such that the electrode assembly 22 is located between the protrusion 214 and the second wall 212 in the axial direction of the cylindrical battery cell 20.

[0178] It should be noted that the axial direction of the cylindrical battery cell 20 is the extension direction of the central axis of the cylindrical battery cell 20. Correspondingly, the axial direction and the radial direction of the cylindrical battery cell 20 are perpendicular to each other. The radial direction of the cylindrical battery cell 20 is the direction in which the central axis of the cylindrical battery cell 20 points to the outer peripheral surface of the cylindrical battery cell 20 or the outer peripheral surface of the cylindrical battery cell 20 points to the central axis of the cylindrical battery cell 20 in a projection plane perpendicular to the axial direction of the cylindrical battery cell 20. Correspondingly, the side wall 213 of the outer casing 21 is also a cylindrical structure, and the central axis of the side wall 213 of the outer casing 21 extends along the axial direction of the cylindrical battery cell 20, so that the projections of the first wall 211 and the second wall 212 on the axial direction of the cylindrical battery cell 20 are both circular.

[0179] In this embodiment, the electrode assembly 22 is the component in the cylindrical battery cell 20 where the electrochemical reaction occurs. The electrode assembly 22 includes a main body 221, a first tab 222, and a second tab 223. The main body 221 is the primary component in the electrode assembly 22 where the electrochemical reaction occurs in the cylindrical battery cell 20, while the first tab 222 and the second tab 223 serve to output or input electrical energy to the electrode assembly 22. The structure of the main body 221 of the electrode assembly 22 can be varied. For example, in FIG. 4, the main body 221 of the electrode assembly 22 is a wound structure formed by winding a portion of the positive electrode, a separator, and a portion of the negative electrode, and the main body 221 of the electrode assembly 22 has a cylindrical structure. The central axis of the main body 221 of the electrode assembly 22 extends along the axial direction of the cylindrical battery cell 20.

[0180] For example, the separator is a separator membrane, and the main material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0181] Optionally, the electrode assembly 22 housed within the housing 21 can be one or more. For example, in Figure 4, only one electrode assembly 22 is provided within the housing 21 of the cylindrical battery cell 20. Of course, the structure of the cylindrical battery cell 20 is not limited to this; in other embodiments, the electrode assembly 22 housed within the housing 21 can be two, three, four, five, six, seven, or eight, etc.

[0182] The first tab 222 and the second tab 223 have opposite polarities. The first tab 222 and the second tab 223 are used as the positive and negative electrodes of the input or output electrode assembly 22, respectively. In Figures 5 and 6, the first tab 222 and the second tab 223 are connected to the two ends of the main body 221 in the axial direction of the cylindrical battery cell 20. The first tab 222 is located at the end of the main body 221 facing the first wall 211, and the second tab 223 is located at the end of the main body 221 away from the first wall 211.

[0183] It should be noted that if the first tab 222 is the positive tab of the electrode assembly 22, then the first tab 222 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. Correspondingly, if the second tab 223 is the negative tab of the electrode assembly 22, then the second tab 223 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. Conversely, if the first tab 222 is the negative tab of the output electrode assembly 22, then the first tab 222 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. Correspondingly, if the second tab 223 is the positive tab of the electrode assembly 22, then the second tab 223 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.

[0184] The first connecting area 232 of the first current collector 23 and the first connecting wall 2141 of the protrusion 214 are welded together to form a connecting part 24. It should be noted that the connecting part 24 is a region where the first connecting area 232 of the first current collector 23 and the first connecting wall 2141 of the protrusion 214 are welded together to form a region that is mutually fused or a region where a weld mark is formed.

[0185] The protrusion 214 is a convex structure protruding from the inner wall surface of the sidewall 213 facing the electrode assembly 22. For example, the protrusion 214 is an annular structure extending circumferentially along the sidewall 213. The first connecting wall 2141 of the protrusion 214 is one wall of the protrusion 214. If the protrusion 214 is a solid structure, then the entire protrusion 214 is the first connecting wall 2141. If the protrusion 214 is a hollow structure, for example, as shown in Figures 6 and 7, a groove 2132 is formed on the surface of the sidewall 213 facing away from the electrode assembly 22 and corresponding to the position of the protrusion 214. Correspondingly, the first connecting wall 2141 is one groove sidewall 213 of the groove 2132, so that the protrusion 214 includes two first connecting walls 2141 and one second connecting wall 2141. The wall 2142 consists of two first connecting walls 2141 arranged opposite each other along the first direction X, and a second connecting wall 2142 connected between the two first connecting walls 2141. That is, the two first connecting walls 2141 are the two groove side walls 213 of the groove 2132 facing each other in the first direction X, and the second connecting wall 2142 is the bottom wall of the groove 2132. It should be noted that one of the two first connecting walls 2141 is welded to the first connecting area 232 of the first current collecting member 23 to form a connecting part 24.

[0186] In this embodiment, the first direction X is the stacking direction of the first connecting area 232 of the first current collector 23 and the first connecting wall 2141 of the protrusion 214. For example, in Figures 5 and 6, the first direction X is parallel to the axial direction of the cylindrical battery cell 20. Correspondingly, the second direction Y is the radial direction of the cylindrical battery cell 20. Of course, in other embodiments, the first direction X can also be a structure that is set at an angle to the axial direction of the cylindrical battery cell 20. For example, the protrusion 214 bends away from the first wall 211 or towards the first wall 211 in the axial direction of the cylindrical battery cell 20, or the first connecting wall 2141 is an inclined structure, so that the first direction X is set at an angle to the axial direction of the cylindrical battery cell 20.

[0187] For example, the first current collector 23 is located on the side of the electrode assembly 22 facing the first wall 211 in the axial direction of the cylindrical battery cell 20, such that the main body 221, the first tab 222, the first current collector 23 and the first wall 211 are arranged sequentially along the axial direction of the cylindrical battery cell 20. Optionally, the main body region 2141a of the first current collector 23 is located between the protrusion 214 and the electrode assembly 22 to support the electrode assembly 22, and the first connection region 232 is located on the side of the main body region 2141a facing the first wall 211 in the axial direction of the cylindrical battery cell 20.

[0188] Optionally, the welding connection between the first connecting area 232 of the first current collector 23 and the first connecting wall 2141 of the protrusion 214 can be of various types, such as laser welding or ultrasonic welding.

[0189] The body region 231 of the first current collector 23 is disposed at one end of the electrode assembly 22 in the axial direction of the cylindrical battery cell 20 near the first wall 211, and the body region 231 is connected to the first tab 222 to realize the electrical connection between the first current collector 23 and the first tab 222. Optionally, the body region 231 is connected to the side of the first tab 222 in the axial direction of the cylindrical battery cell 20 away from the main body 221, and the first connection region 232 is welded to the first connection wall 2141 of the protrusion 214 to realize the electrical connection between the electrode assembly 22 and the side wall 213 of the outer casing 21, so that the side wall 213 of the outer casing 21 serves as an output electrode of the cylindrical battery cell 20.

[0190] Optionally, the connection structure between the body region 231 of the first current collector 23 and the first electrode 222 can be various, such as welding or bonding.

[0191] The first connection area 232 is located on the side of the body area 231 facing the first wall 211 along the axial direction of the cylindrical battery cell 20, and the first connection area 232 and the body area 231 are spaced apart along the axial direction of the cylindrical battery cell 20. That is, the body area 231 and the first connection area 232 are arranged at intervals along the axial direction of the cylindrical battery cell 20, and the first connection area 232 is closer to the first wall 211 in the axial direction of the cylindrical battery cell 20 than the body area 231.

[0192] In this embodiment of the application, the protrusion 214 includes a main body region 2141a and a second connecting region 2141b that are connected to each other, and the main body region 2141a and the second connecting region 2141b are arranged side by side along the second direction Y. That is, the main body region 2141a of the protrusion 214 is connected to at least one side of the second connecting region 2141b in the second direction Y, so that the main body region 2141a and the second connecting region 2141b are arranged in the second direction Y.

[0193] For example, in Figures 6, 7 and 8, the second connecting region 2141b is connected to the main body region 2141a on both sides along the second direction Y. That is, the second connecting region 2141b is connected between the two main body regions 2141a in the second direction Y.

[0194] The connecting part 24 is partially embedded in the second connecting area 2141b, and the connecting part 24 is connected to the main body area 2141a through the second connecting area 2141b. That is, the first current collecting member 23 is welded to the second connecting area 2141b of the first connecting wall 2141 of the protrusion 214 to form the connecting part 24, and the second connecting area 2141b covers part of the connecting part 24, so that the connecting part 24 is connected to the main body area 2141a through the second connecting area 2141b. It should be noted that the connecting part 24 is partially embedded in the first current collecting member 23, and the connecting part 24 is partially embedded in the first connecting wall 2141 of the protrusion 214. The second connecting area 2141b of the first connecting wall 2141 is a structure that covers the outside of the part of the connecting part 24 embedded in the first connecting wall 2141. The main body area 2141a is the area on both sides of the first connecting wall 2141 of the protrusion 214 located in the second connecting area 2141b in the second direction Y. That is, the main body area 2141a is the conventional area of ​​the first connecting wall 2141 of the protrusion 214.

[0195] Optionally, the second connection area 2141b may be formed by locally softening the first connection wall 2141 before the first connection area 232 and the first connection wall 2141 of the first current collector 23 are welded together, or the second connection area 2141b may be formed by reducing the hardness of the area around the connection part 24 by controlling the welding power during the welding process of the first connection area 232 and the first connection wall 2141 of the first current collector 23.

[0196] It should be noted that the first connecting area 232 and the second connecting area 2141b of the first connecting wall 2141 are stacked along the first direction X, such that the first connecting area 232 is located on one side of the second connecting area 2141b of the first connecting wall 2141 in the first direction X. Optionally, in the first direction X, the connecting part 24 can be a structure that penetrates the second connecting area 2141b or a structure that does not penetrate the second connecting area 2141b. For example, in Figures 6 and 8, the connecting part 24 does not penetrate the second connecting area 2141b in the first direction X. Correspondingly, the portion of the second connecting area 2141b... The second connecting region 2141b is located on the outer periphery of the connecting portion 24, that is, a portion of the second connecting region 2141b is disposed around the connecting portion 24, and a portion of the second connecting region 2141b is located on one side of the connecting portion 24 in the first direction X. In other words, the connecting portion 24 is a structure in which one end in the first direction X is inserted into the second connecting region 2141b. Of course, in other embodiments, the connecting portion 24 may also be a structure that penetrates the second connecting region 2141b in the first direction X. Correspondingly, the second connecting region 2141b is only a structure located on the outer periphery of the connecting portion 24, such that the second connecting region 2141b is disposed around the connecting portion 24.

[0197] In this embodiment of the application, at least a portion of the grains in the second connection region 2141b are first grains 2141c, and the ratio of the number of first grains 2141c to the total number of grains in the second connection region 2141b is greater than 50%. That is, the proportion of the number of first grains 2141c in the second connection region 2141b is greater than 50%, meaning that more than half of the grains in the second connection region 2141b are first grains 2141c.

[0198] The second connecting region 2141b intersects with the preset plane to form a first cross section. The preset plane is parallel to the first direction X and the second direction Y. That is, as shown in Figures 7 and 8, the preset plane is a plane that is parallel to the first direction X and the second direction Y. The cross section of the second connecting region 2141b cut by the preset plane is the first cross section.

[0199] Within the first cross section, the longest line among the multiple lines connecting any two points on the outer contour of the first grain 2141c is the first connecting line 2141d. That is, the first connecting line 2141d is the longest straight line connecting any two points on the outer edge of the first grain 2141c within the first cross section. For example, for ease of description, in Figure 8, the size of the first grain 2141c in the second direction Y is greater than the size of the first grain 2141c in the first direction X. Correspondingly, the length of the first connecting line 2141d is D1.

[0200] Within the first cross section, among the multiple lines connecting any two points on the outer contour of the first grain 2141c, there is also a second connecting line 2141e. The second connecting line 2141e is perpendicular to the first connecting line 2141d and passes through the midpoint of the first connecting line 2141d. That is, the second connecting line 2141e is a straight line among the multiple straight lines connecting any two points on the outer edge of the first grain 2141c within the first cross section that is perpendicular to the first connecting line 2141d and passes through the midpoint of the first connecting line 2141d. For example, for ease of description, in Figure 8, the second connecting line 2141e is a straight line that is perpendicular to the first connecting line 2141d and passes through the midpoint of the first connecting line 2141d. Correspondingly, the length of the second connecting line 2141e is D2.

[0201] The ratio of the length of the first connection 2141d to the length of the second connection 2141e ranges from 1 to 5, that is, in Figure 8, 1≤D1 / D2≤5. In other words, the first grain 2141c is an equiaxed crystal, and correspondingly, the proportion of equiaxed crystals in the second connection region 2141b is greater than 50%.

[0202] In this design, at least some of the grains within the main region 2141a are second grains 2141f, and the ratio of the number of second grains 2141f to the total number of grains within the main region 2141a is greater than 50%. The main region 2141a intersects with a preset plane to form a second cross section. Within this second cross section, the longest line among multiple lines connecting any two points on the outer contour of the second grain 2141f is the third line 2141g. Furthermore, the multiple lines connecting any two points on the outer contour of the second grain 2141f also include a fourth line 2141h, which is perpendicular to the third line 2141g and passes through the midpoint of the third line 2141g. The ratio of the length of the third line 2141g to the length of the fourth line 2141h ranges from 5 to 100. It should be noted that the first and second cross sections are coplanar structures, and both the first and second cross sections are located within the preset plane.

[0203] In this embodiment of the application, the steps of measuring the grains in the second connection region 2141b include sample cutting, sample processing, and grain measurement.

[0204] The sample cutting steps specifically include:

[0205] The sidewall 213 is cut along its circumference at a distance of 30 mm from the second wall 212 of the cylindrical battery cell 20. The electrode assembly 22 and electrolyte inside the housing 21 are separated from the housing 21. The sidewall 213 with the first wall 211 and protrusion 214 after cutting is cleaned and the cleaned sidewall 213 is restored to flatness. Crystal glue is poured into the space formed by the sidewall 213 and the first wall 211, and the height of the crystal glue in the space formed by the sidewall 213 and the first wall 211 in the axial direction of the cylindrical battery cell 20 is greater than or equal to a preset height. The preset height is half the height of the sidewall 213 with protrusion 214 in the axial direction of the cylindrical battery cell 20 after cutting. Then the sidewall 213 is cut again, with the cutting surface parallel to the first direction X and the second direction Y, and the cutting surface passes through the entire protrusion 214, so that the cross section of the protrusion 214 is a preset plane to obtain the test sample.

[0206] Sample processing specifically includes:

[0207] The cut surface of the protrusion 214 of the test sample is polished with sandpaper with a grit greater than or equal to 1600. The cut surface of the polished protrusion 214 is then cleaned and etched to obtain a test sample that can be observed under an optical microscope. The etched test sample is then placed under an optical microscope to observe the cut surface of the protrusion 214 of the test sample.

[0208] The grains on the cut surface of protrusion 214 can be measured using an Olympus BX53M optical microscope. By selecting a general area to be measured at a lower magnification using the optical microscope, and then increasing the magnification to observe this area, the measurement location can be determined. It is understood that the proportion of first grains 2141c in the second connecting region 2141b is greater than 50%, and the proportion of second grains 2141f in the main region 2141a is greater than 50%, making the grain differences between the second connecting region 2141b and the main region 2141a quite significant. The approximate area to be measured can be identified by observing the grains under the optical microscope.

[0209] The grains displayed under an optical microscope on the BX53M model can be measured using Olympus's corresponding software, such as Capture 2.2.1.

[0210] The specific steps for measuring the grains within the second connection region 2141b include:

[0211] The crystal grains under the optical microscope of model BX53M were displayed and measured using the software Capture2.2.1. A first rectangular frame of 0.1mm × 0.2mm was drawn in the second connection area 2141b. The side of the first rectangular frame with a side length of 0.2mm was parallel to the second direction Y. The crystal grains completely within the first rectangular frame and the crystal grains intersecting with the side of the first rectangular frame were all considered to be within the first rectangular frame.

[0212] Measure the length of the longest first line 2141d connecting any two points on the outer contour of each grain within the first rectangular frame of 0.1mm × 0.2mm, and the length of the second line 2141e perpendicular to the first line 2141d and passing through the midpoint of the first line 2141d. The lengths of the first line 2141d and the second line 2141e for each grain are the dimensions under the system scale corresponding to the software Capture2.2.1, that is, the actual dimensions without being magnified by an optical microscope. These dimensions will not change with the magnification of the optical microscope.

[0213] It should be noted that the 0.1mm × 0.2mm first rectangular frame refers to the first rectangular frame having two sides with a length of 0.1mm arranged opposite each other along the second direction Y, and a side with a length of 0.2mm parallel to the second direction Y. The first rectangular frame also has two sides with a length of 0.2mm arranged opposite each other along the first direction X. The dimensions of the first rectangular frame are those under the system scale corresponding to the Capture 2.2.1 software, i.e., the actual dimensions without magnification by an optical microscope. This dimension will not change with changes in the magnification of the optical microscope.

[0214] The grains are screened by measuring the lengths of the first connection line 2141d and the second connection line 2141e of each grain within the 0.1mm × 0.2mm first rectangular frame. If the ratio of the length of the first connection line 2141d to the length of the second connection line 2141e of a grain within the 0.1mm × 0.2mm first rectangular frame is within the range of 1 to 5, then that grain is the first grain 2141c within the second connection region 2141b. The first grain 2141c within the 0.1mm × 0.2mm first rectangular frame is thus selected. The ratio of the number of first grains 2141c within the 0.1mm×0.2mm first rectangular frame to the total number of grains within the 0.1mm×0.2mm first rectangular frame is greater than 50%. This means that the ratio of the number of first grains 2141c within the first cross-section of the second connecting region 2141b to the total number of grains within the first cross-section of the second connecting region 2141b is greater than 50%. Therefore, the ratio of the number of first grains 2141c within the second connecting region 2141b to the total number of grains within the second connecting region 2141b is greater than 50%.

[0215] For example, the ratio of the length D1 of the first connection 2141d to the length D2 of the second connection 2141e can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.4, 2.5, 2.6, 2.8, 3, 3.1, 3.3, 3.5, 3.7, 4, 4.2, 4.5, 4.7, 4.8, 4.9, or 5, etc.

[0216] Optionally, the first current collector 23 can be made of various materials, such as copper, iron, aluminum, steel or aluminum alloy.

[0217] In some embodiments, the first current collector 23 is made of copper, and the surface of the protrusion 214 is covered with a plating layer. The protrusion 214 is made of steel, and the plating layer is made of nickel. This structure of the cylindrical battery cell 20 can further improve the welding reliability between the protrusion 214 and the first current collector 23, and also reduce the risk of rust and corrosion on the protrusion 214.

[0218] In some embodiments, as shown in Figures 3, 4 and 5, the cylindrical battery cell 20 may further include an electrode terminal 25, which is insulated and mounted on the second wall 212 of the housing 21. The electrode terminal 25 is electrically connected to the second tab 223, so that the electrode terminal 25 serves as another output electrode of the cylindrical battery cell 20, thereby enabling the input or output of electrical energy of the cylindrical battery cell 20 through the electrode terminal 25 and the side wall 213 of the housing 21.

[0219] The electrode terminal 25 is insulatedly mounted on the second wall 212 of the housing 21. That is, the electrode terminal 25 is mounted on the end of the housing 21 away from the first wall 211 in the axial direction of the cylindrical battery cell 20, and an insulating element is provided between the electrode terminal 25 and the second wall 212 of the housing 21, so that no electrical connection is formed between the electrode terminal 25 and the second wall 212 of the housing 21.

[0220] Referring to Figure 5, the electrode terminal 25 is riveted to the second wall 212 of the housing 21. Specifically, the second wall 212 of the housing 21 has mounting holes 2121 that extend along the axial direction of the cylindrical battery cell 20 through both sides of the second wall 212. A portion of the electrode terminal 25 passes through the mounting holes 2121. The electrode terminal 25 has a first clamping portion located on the side of the second wall 212 facing the electrode assembly 22 and a second clamping portion located on the side of the second wall 212 away from the electrode assembly 22. At least a portion of the second wall 212 of the housing 21 is located axially between the first and second clamping portions of the cylindrical battery cell 20, allowing the first and second clamping portions to cooperate in clamping the second wall 212 of the housing 21, thereby riveting the electrode terminal 25 to the second wall 212 of the housing 21. Of course, in other embodiments, the electrode terminal 25 can also be snap-fitted or glued to the housing 21.

[0221] For example, the electrode terminal 25 can be made of various materials, such as copper, iron, aluminum, steel or aluminum alloy.

[0222] In some embodiments, as shown in Figures 4 and 5, the cylindrical battery cell 20 may further include a second current collector 26 disposed axially between the second wall 212 of the housing 21 and the electrode terminal 25 of the cylindrical battery cell 20. The second current collector 26 connects the second tab 223 and the electrode terminal 25 to electrically connect the electrode assembly 22 and the electrode terminal 25.

[0223] Optionally, the connection structure between the second current collector 26 and the second electrode tab 223, and between the second current collector 26 and the electrode terminal 25, can be various, such as welding connection or bonding.

[0224] For example, the material of the second current collector 26 can be various, such as copper, iron, aluminum, steel or aluminum alloy.

[0225] It should be noted that in other embodiments, the second tab 223 of the electrode assembly 22 may also be a structure that is directly connected to the electrode terminal 25, such as by welding or bonding.

[0226] In some embodiments, the cylindrical battery cell 20 may further include a pressure relief component disposed on the housing 21, which is used to release the internal pressure of the cylindrical battery cell 20 when the internal pressure or temperature of the cylindrical battery cell 20 reaches a predetermined value.

[0227] The pressure relief component can be disposed on the first wall 211 or the second wall 212 of the outer casing 21. Similarly, the pressure relief component and the outer casing 21 can be integrally formed or separate components. If the pressure relief component and the outer casing 21 are integrally formed, the pressure relief component is part of the outer casing 21, and the weak structure on the pressure relief component for pressure relief is the area on the outer casing 21 where a weak structure is formed. This allows the outer casing 21 to be configured to at least partially crack along the weak structure when the cylindrical battery cell 20 is depressurized, thereby releasing the internal pressure of the cylindrical battery cell 20. Of course, in other embodiments, the pressure relief component and the outer casing 21 can also be separate components. The pressure relief component can be connected to the outer casing 21 by welding or other means. Correspondingly, the pressure relief component can be a component such as an explosion-proof valve, explosion-proof disc, gas valve, pressure relief valve, or safety valve.

[0228] In this embodiment, a first current collector 23 is provided inside the outer casing 21. The body region 231 of the first current collector 23 is connected to the first tab 222 of the electrode assembly 22, and the first connection region 232 of the first current collector 23 is welded to the first connection wall 2141 of the protrusion 214, so as to realize that the cylindrical battery cell 20 can input or output electrical energy through the side wall 213 of the outer casing 21. The first connection wall 2141 of the protrusion 214 includes a main body region 2141a and a second connection region arranged side by side along the second direction Y. Region 2141b, and a portion of the connecting part 24 formed by welding the first connecting region 232 and the first connecting wall 2141 is embedded in and connected to the second connecting region 2141b, so that the first connecting region 232 of the first current collector 23 has a structure in which it is welded to the second connecting region 2141b to form the connecting part 24. By setting the ratio of the length of the first connecting line 2141d and the length of the second connecting line 2141e in the first cross section of the first grain 2141c to 1 to 5, the first grain 2141c 41c consists of equiaxed grains with small differences in outer contour dimensions, and the proportion of the first grain 2141c within the second connection region 2141b is greater than 50%. This results in a higher proportion of equiaxed grains within the second connection region 2141b, leading to less constraint between the grains and thus better toughness in the second connection region 2141b, making it easier for the second connection region 2141b to deform. Cylindrical cell 20 with this structure experiences deformation during use due to the shaking of the electrode assembly 22. When the current collector 23 pulls on the protrusion 214 and the side wall 213, the second connection area 2141b can play a certain buffering role between the connection part 24 and the main body area 2141a, thereby effectively relieving the rigid pulling between the first current collector 23 and the protrusion 214. This helps to reduce the phenomenon of welding detachment of the first current collector 23 and the protrusion 214 during use, thereby reducing the risk of connection failure between the electrode assembly 22 and the side wall 213 of the outer casing 21, and improving the stability and service life of the cylindrical battery cell 20.

[0229] According to some embodiments of this application, referring to FIG8, the ratio of the length of the first connecting line 2141d to the length of the second connecting line 2141e ranges from 1 to 3. That is, in FIG8, 1≤D1 / D2≤3.

[0230] In this embodiment, by further setting the ratio of the length of the first connecting line 2141d and the length of the second connecting line 2141e within the first cross section of the first grain 2141c to 1 to 3, the dimensional difference of the outer contour of the first grain 2141c is further reduced, which is beneficial to further improve the shape regularity of the first grain 2141c. This can further reduce the constraint force between grains in the second connecting region 2141b, thereby further improving the toughness of the second connecting region 2141b. This is beneficial to further improve the buffering effect of the second connecting region 2141b between the connecting part 24 and the main body region 2141a, and further reduce the rigid tension between the first current collector 23 and the protrusion 214, thereby further alleviating the phenomenon of weld detachment between the first current collector 23 and the protrusion 214.

[0231] According to some embodiments of this application, please continue to refer to Figure 8, the length of the first connecting line 2141d and the length of the second connecting line 2141e are both 5μm to 200μm. That is, in Figure 8, 5μm≤D1≤200μm and 5μm≤D2≤200μm.

[0232] For example, the length D1 of the first connection 2141d can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, or 200μm, etc.

[0233] For example, the length D2 of the second connection 2141e can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm or 200μm, etc.

[0234] In this embodiment, by setting the lengths of the first connecting line 2141d and the second connecting line 2141e within the first cross section of the first grain 2141c to be both between 5μm and 200μm, the difference in volume and outer contour of the first grain 2141c is small. This helps to further reduce the constraint force between grains in the second connecting region 2141b, giving the second connecting region 2141b better toughness. This further enhances the buffering effect of the second connecting region 2141b between the connecting part 24 and the main body region 2141a, thereby reducing the rigid tension between the first current collector 23 and the protrusion 214.

[0235] According to some embodiments of this application, referring to Figures 6, 7 and 8, at least some of the grains in the main body region 2141a are second grains 2141f. The ratio of the number of second grains 2141f to the total number of grains in the main body region 2141a is greater than 50%. The main body region 2141a intersects with a preset plane to form a second cross section. In the second cross section, the longest line among the multiple lines connecting any two points on the outer contour of the second grain 2141f is the third line 2141g. The multiple lines connecting any two points on the outer contour of the second grain 2141f also include a fourth line 2141h. The fourth line 2141h is perpendicular to the third line 2141g and passes through the midpoint of the third line 2141g. The ratio of the length of the third line 2141g to the length of the fourth line 2141h is in the range of 5 to 100.

[0236] Among them, at least some of the grains in the main region 2141a are second grains 2141f, and the ratio of the number of second grains 2141f to the total number of grains in the main region 2141a is greater than 50%. In other words, the proportion of the number of second grains 2141f in the main region 2141a is greater than 50%, that is, more than half of the grains in the main region 2141a are second grains 2141f.

[0237] The main body region 2141a intersects with the preset plane to form a second cross section. The preset plane is parallel to the first direction X and the second direction Y. That is, as shown in Figures 7 and 8, the preset plane is a plane that is parallel to the first direction X and the second direction Y. The cross section of the main body region 2141a cut by the preset plane is the second cross section.

[0238] Within the second cross-section, the longest line among the multiple lines connecting any two points on the outer contour of the second grain 2141f is the third line 2141g. That is, the third line 2141g is the longest straight line connecting any two points on the outer edge of the second grain 2141f within the second cross-section. For example, for ease of description, in Figure 8, the dimension of the second grain 2141f in the second direction Y is greater than its dimension in the first direction X. Correspondingly, the length of the third line 2141g is D3. It should be noted that if the length direction of the second grain 2141f forms a non-zero angle with the second direction Y, then the length of the second grain 2141f is the length D3 of the third line 2141g.

[0239] Within the second cross section, among the multiple lines connecting any two points on the outer contour of the second grain 2141f, there is also a fourth connecting line 2141h. The fourth connecting line 2141h is perpendicular to the third connecting line 2141g and passes through the midpoint of the third connecting line 2141g. That is, the fourth connecting line 2141h is a straight line among the multiple straight lines connecting any two points on the outer edge of the second grain 2141f within the second cross section that is perpendicular to the third connecting line 2141g and passes through the midpoint of the third connecting line 2141g. For example, for ease of description, in Figure 8, the fourth connecting line 2141h is a straight line that is perpendicular to the third connecting line 2141g and passes through the midpoint of the third connecting line 2141g. Correspondingly, the length of the fourth connecting line 2141h is D4.

[0240] The ratio of the length of the third connection 2141g to the length of the fourth connection 2141h ranges from 5 to 100, that is, in Figure 8, 5 ≤ D3 / D4 ≤ 100. In other words, the second grain 2141f is a banded crystal, and correspondingly, the proportion of banded crystals in the main region 2141a is greater than 50%.

[0241] In this embodiment of the application, the step of measuring the grains in the main body region 2141a includes sample cutting, sample processing, and grain measurement. Referring to the method for measuring the grains in the second connection region 2141b described above, the sample cutting and sample processing in the step of measuring the grains in the main body region 2141a are the same as those in the step of measuring the grains in the second connection region 2141b.

[0242] The specific steps for measuring grains within the main region 2141a include:

[0243] The crystal grains under an optical microscope of model BX53M were displayed and measured using the software Capture2.2.1. A second rectangle of 0.1mm × 0.2mm was drawn in the main area 2141a. The side of the second rectangle with a side length of 0.2mm was parallel to the second direction Y. The crystal grains completely within the second rectangle and the crystal grains intersecting the side of the second rectangle were all considered to be within the second rectangle.

[0244] Measure the length of the longest third line 2141g and the length of the fourth line 2141h that is perpendicular to the third line 2141g and passes through the midpoint of the third line 2141g within the second rectangular frame of 0.1mm×0.2mm. The lengths of the third line 2141g and the fourth line 2141h of each grain are the dimensions under the system scale corresponding to the software Capture2.2.1, that is, the actual dimensions without being magnified by an optical microscope. These dimensions will not change with the magnification of the optical microscope.

[0245] It should be noted that the 0.1mm × 0.2mm second rectangle refers to the two sides of the second rectangle arranged opposite each other along the second direction Y with a side length of 0.1mm, and the side with a side length of 0.2mm parallel to the second direction Y. The two sides of the second rectangle arranged opposite each other along the first direction X also have a side length of 0.2mm. The dimensions of the second rectangle are those under the system scale corresponding to the Capture 2.2.1 software, i.e., the actual dimensions without magnification by an optical microscope. This dimension will not change with changes in the magnification of the optical microscope.

[0246] The grains are screened by measuring the lengths of the third connection line 2141g and the fourth connection line 2141h of each grain within the 0.1mm × 0.2mm second rectangular frame. If the ratio of the length of the third connection line 2141g to the length of the fourth connection line 2141h of the grains within the 0.1mm × 0.2mm second rectangular frame is within the range of 5 to 100, then that grain is the second grain 2141f within the main region 2141a. The second grain 2141f within the 0.1mm × 0.2mm second rectangular frame is thus selected. The ratio of the number of second grains 2141f within the second rectangular frame of 0.1mm × 0.2mm to the total number of grains within the second rectangular frame of 0.1mm × 0.2mm is greater than 50%. This means that the ratio of the number of second grains 2141f within the second cross section of the main region 2141a to the total number of grains within the second cross section of the main region 2141a is greater than 50%.

[0247] For example, the ratio of the length D3 of the third connection 2141g to the length D4 of the fourth connection 2141h can be 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100, etc.

[0248] In this embodiment, by setting the ratio of the length of the third connecting line 2141g to the length of the fourth connecting line 2141h of the second grain 2141f in the second cross section to 5 to 100, the second grain 2141f is a banded grain with a large difference in the size of its outer contour, and the proportion of the second grain 2141f in the main region 2141a is greater than or equal to 50%, so that the proportion of banded grains in the main region 2141a is relatively large, thereby making the constraint force between the grains in the main region 2141a larger, which is beneficial to improving the strength and deformation resistance of the main region 2141a, and thus reducing the risk of cracking or damage to the main region 2141a of the protrusion 214 during use.

[0249] In some embodiments, referring to Figure 8, the length of the third connection 2141g is 150μm to 1000μm, and the length of the fourth connection 2141h is 5μm to 120μm. That is, in Figure 8, 150μm≤D3≤1000μm, 5μm≤D4≤120μm.

[0250] For example, the length D3 of the third connection 2141g can be 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 250μm, 280μm, 300μm, 320μm, 350μm, 380μm, 400μm, 420μm, 450μm, 480μm, or 500μm. , 520μm, 550μm, 580μm, 600μm, 620μm, 650μm, 680μm, 700μm, 750μm, 800μm, 810μm, 820 μm, 850μm, 860μm, 870μm, 880μm, 890μm, 900μm, 920μm, 950μm, 980μm, 990μm or 1000μm, etc.

[0251] For example, the length D4 of the fourth connection line 2141h may be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 15 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 28 μm, 30 μm, 35 μm. , 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 96μm, 97μm, 98μm, 99μm, 100μm, 105μm, 110μm, 115μm or 120μm, etc.

[0252] In this embodiment, by setting the length of the third connecting line 2141g of the second grain 2141f in the second cross section to 150μm to 1000μm, and setting the length of the fourth connecting line 2141h of the second grain 2141f in the second cross section to 5μm to 120μm, the second grain 2141f is made into a strip-shaped grain with a large difference in the size of its outer contour. This not only improves the strength and deformation resistance of the main body region 2141a, but also alleviates the phenomenon of excessive size difference in the outer contour of the second grain 2141f, thereby reducing the molding difficulty of the second grain 2141f in the main body region 2141a, and thus effectively reducing the manufacturing cost of the cylindrical battery cell 20.

[0253] According to some embodiments of this application, referring to Figure 8, the angle between the extension direction of the third connecting line 2141g and the second direction Y is 0° to 30°. That is, the length direction of the third connecting line 2141g in the second cross section of the second grain 2141f is approximately the second direction Y.

[0254] For example, the angle between the extension direction of the third line 2141g and the second direction Y can be 0 degrees, 1 degree, 2 degrees, 3 degrees, 4 degrees, 5 degrees, 6 degrees, 7 degrees, 8 degrees, 9 degrees, 10 degrees, 11 degrees, 12 degrees, 13 degrees, 14 degrees, 15 degrees, 16 degrees, 17 degrees, 18 degrees, 19 degrees, 20 degrees, 21 degrees, 22 degrees, 25 degrees, 28 degrees or 30 degrees, etc.

[0255] Optionally, the extension direction of the third connecting line 2141g is parallel to the second direction Y, that is, the length direction of the second grain 2141f is parallel to the second direction Y. It should be noted that the second direction Y is the arrangement direction of the main body region 2141a and the second connecting region 2141b of the first connecting wall 2141 of the protrusion 214. At the same time, the second direction Y is also the stretching direction of the first connecting wall 2141 of the protrusion 214 during the forming process, so that the second direction Y is also the stretching and extension direction of the grains in the first connecting wall 2141.

[0256] In this embodiment, by setting the extension direction of the third connecting line 2141g of the second grain 2141f in the second cross section to an angle of 0 to 30 degrees with the second direction Y, the length direction of the second grain 2141f is approximately the second direction Y. This ensures that the length direction of the second grain 2141f is consistent with the arrangement direction of the main body region 2141a and the second connecting region 2141b. This reduces the molding difficulty of the second grain 2141f in the main body region 2141a, thereby reducing the manufacturing difficulty of the protrusion 214. Furthermore, it enhances the strength and deformation resistance of the main body region 2141a, further reducing the risk of cracking or damage to the main body region 2141a of the protrusion 214 during use.

[0257] According to some embodiments of this application, as shown in FIG8, the length of the third connection 2141g is greater than the length of the first connection 2141d, that is, D3 > D1.

[0258] In this embodiment, by setting the length of the third connection line 2141g of the second grain 2141f in the second cross section to be greater than the length of the first connection line 2141d of the first grain 2141c in the first cross section of the second connecting region 2141b, the space occupied by the first grain 2141c is less than the space occupied by the second grain 2141f, and the number of first grains 2141c contained in the second connecting region 2141b per unit area is greater than the number of first grains 2141c contained in the main region 2141a per unit area. The number of second grains 2141f contained in the area is increased so that the grain size of the second connecting region 2141b is higher than that of the main region 2141a, so that the second connecting region 2141b has better plasticity and toughness than the main region 2141a, and thus the second connecting region 2141b is more likely to deform. This is beneficial to improving the buffering effect of the second connecting region 2141b between the connecting part 24 and the main region 2141a, so as to reduce the rigid tension between the first current collector 23 and the protrusion 214.

[0259] In some embodiments, as shown in Figure 8, the ratio of the length of the third connection 2141g to the length of the first connection 2141d ranges from 1.5 to 150, that is, 1.5 ≤ D3 / D1 ≤ 150.

[0260] For example, the ratio of the length D3 of the third connection 2141g to the length D1 of the first connection 2141d can be 1.5, 1.6, 1.7, 1.8, 1.9, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140 or 150, etc.

[0261] In this embodiment, by setting the length of the third connecting line 2141g of the second grain 2141f in the second cross section of the main body region 2141a to 1.5 to 150 times the length of the first connecting line 2141d of the first grain 2141c in the first cross section of the second connecting region 2141b, on the one hand, the space occupied by the first grain 2141c can be further reduced to the space occupied by the second grain 2141f, so that the number of first grains 2141c contained in the second connecting region 2141b per unit area is greater than the number of second grains 2141f contained in the main body region 2141a per unit area, thereby further improving the grain size of the second connecting region 2141b, so that the second connecting region 2141b has better plasticity and toughness than the main body region 2141a, and thus... While improving the toughness of the second connecting region 2141b, it also enhances the strength and deformation resistance of the main body region 2141a. This allows the second connecting region 2141b to act as a better buffer between the connecting part 24 and the main body region 2141a, while also improving the overall structural strength of the main body region 2141a. This reduces the risk of large-area deformation of the first connecting wall 2141 of the protrusion 214 during use. On the other hand, it can alleviate the phenomenon of excessive size difference between the second grain 2141f in the main body region 2141a and the first grain 2141c in the second connecting region 2141b. This helps to reduce the molding difficulty of the second grain 2141f in the main body region 2141a and the first grain 2141c in the second connecting region 2141b, thereby reducing the manufacturing difficulty of the protrusion 214.

[0262] In some embodiments, please continue to refer to Figure 8, the ratio of the length of the third connection 2141g to the length of the first connection 2141d is in the range of 1.8 to 100, that is, 1.8≤D3 / D1≤100.

[0263] In this embodiment, by further setting the length of the third connecting line 2141g of the second grain 2141f in the second cross section of the main body region 2141a to 1.8 to 100 times the length of the first connecting line 2141d of the first grain 2141c in the first cross section of the second connecting region 2141b, on the one hand, the space occupied by the first grain 2141c can be further reduced to the space occupied by the second grain 2141f, so that the number of first grains 2141c contained in the second connecting region 2141b per unit area is greater than the number of second grains 2141f contained in the main body region 2141a per unit area, thereby further improving the grain size of the second connecting region 2141b, so that the second connecting region 2141b has better plasticity and toughness than the main body region 2141a, and thus realizes the second connecting region The improved toughness of 2141b also enhances the strength and deformation resistance of the main body region 2141a. This allows the second connecting region 2141b to act as a better buffer between the connecting part 24 and the main body region 2141a, while also further improving the overall structural strength of the main body region 2141a. This reduces the risk of large-area deformation of the first connecting wall 2141 of the protrusion 214 during use. On the other hand, it also alleviates the problem of excessive size difference between the second grain 2141f in the main body region 2141a and the first grain 2141c in the second connecting region 2141b. This helps to further reduce the molding difficulty of the second grain 2141f in the main body region 2141a and the first grain 2141c in the second connecting region 2141b, thereby reducing the manufacturing difficulty of the protrusion 214.

[0264] According to some embodiments of this application, referring to FIG8, along the second direction Y, the maximum size of the second grain 2141f is greater than the maximum size of the first grain 2141c. That is, along the second direction Y, the maximum distance between the two ends of the second grain 2141f in the second direction Y is greater than the maximum distance between the two ends of the first grain 2141c in the second direction Y.

[0265] In this embodiment, by setting the maximum size of the second grain 2141f in the second direction Y in the main body region 2141a to be greater than the maximum size of the first grain 2141c in the second direction Y in the second connecting region 2141b, the grains in the main body region 2141a have a greater ability to restrain each other in the first direction X than the grains in the second connecting region 2141b. Therefore, when the first connecting region 232 pulls the first connecting wall 2141 of the protrusion 214 along the first direction X, the second connecting region 2141b can have a greater restraint than the main body region 2141a. Better plasticity and toughness make the second connection area 2141b easier to deform, which helps to further improve the buffering effect of the second connection area 2141b between the connection part 24 and the main body area 2141a, thereby further reducing the rigid tension between the first current collector 23 and the protrusion 214. This also helps to further reduce the phenomenon of welding detachment of the first current collector 23 and the protrusion 214 during use, thereby further reducing the risk of connection failure between the electrode assembly 22 and the side wall 213 of the outer casing 21, and further improving the stability and service life of the cylindrical battery cell 20.

[0266] According to some embodiments of this application, as shown in Figures 6, 7 and 8, the Vickers hardness of the second connection region 2141b is less than that of the main body region 2141a.

[0267] The test methods for the Vickers hardness of the second connecting region 2141b and the main body region 2141a can refer to the test methods for Vickers hardness of metals in the national standard GB / T 4340.1-2009.

[0268] In this embodiment, by setting the hardness of the second connection area 2141b to be less than that of the main body area 2141a, when the first connection area 232 of the first current collector 23 pulls on the protrusion 214 due to the shaking of the electrode assembly 22 during the use of the cylindrical battery cell 20, the second connection area 2141b can play a certain buffering role between the connection part 24 and the main body area 2141a. This can alleviate the rigid pulling between the first connection area 232 and the protrusion 214 of the first current collector 23, which helps to reduce the phenomenon of weld detachment between the first connection area 232 and the protrusion 214 of the first current collector 23. In this way, the risk of connection failure between the electrode assembly 22 and the side wall 213 of the outer casing 21 can be reduced during the use of the cylindrical battery cell 20, thereby improving the stability and service life of the cylindrical battery cell 20.

[0269] In some embodiments, the ratio of the Vickers hardness of the second connection region 2141b to the Vickers hardness of the main body region 2141a is 0.3 to 0.8.

[0270] For example, the ratio of the Vickers hardness of the second connecting region 2141b to the Vickers hardness of the main body region 2141a can be 0.3, 0.31, 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.

[0271] In this embodiment, by setting the ratio of the Vickers hardness of the second connecting area 2141b to the Vickers hardness of the main body area 2141a to 0.3 to 0.8, the buffering effect of the second connecting area 2141b between the main body area 2141a and the connecting part 24 is improved, while the structural strength and deformation resistance of the main body area 2141a are further improved. This helps to alleviate the cracking phenomenon of the main body area 2141a during use and reduces the risk of large-area deformation of the first connecting wall 2141 of the protrusion 214 during use.

[0272] In some embodiments, the ratio of the Vickers hardness of the second connection region 2141b to the Vickers hardness of the main body region 2141a is 0.5 to 0.8.

[0273] In this embodiment, by further setting the ratio of the Vickers hardness of the second connecting area 2141b to the Vickers hardness of the main body area 2141a to 0.5 to 0.8, the buffering effect of the second connecting area 2141b between the main body area 2141a and the connecting part 24 is improved, while the structural strength and deformation resistance of the main body area 2141a are also further improved. This helps to further alleviate the cracking phenomenon of the main body area 2141a during use, and further reduces the risk of large-area deformation of the first connecting wall 2141 of the protrusion 214 during use.

[0274] According to some embodiments of this application, as shown in Figures 6, 7 and 8, the Vickers hardness value of the second connection region 2141b is 50 to 160.

[0275] For example, the Vickers hardness of the second connection region 2141b can be 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150 or 160, etc.

[0276] In this embodiment, the Vickers hardness of the second connection area 2141b is 50 to 160. On the one hand, by setting the Vickers hardness of the second connection area 2141b to be greater than or equal to 50, the structural strength of the second connection area 2141b is improved, which helps to alleviate the phenomenon of cracking or damage that occurs when the second connection area 2141b and the first connection area 232 of the first current collector 23 are assembled together or during use, thereby improving the stability of the cylindrical battery cell 20. On the other hand, by setting the Vickers hardness of the second connection area 2141b to be less than or equal to 160, the buffering effect of the second connection area 2141b between the connection part 24 and the main body area 2141a is improved, thereby further alleviating the rigid tension between the first connection area 232 and the protrusion 214 of the first current collector 23, and further reducing the phenomenon of weld detachment between the first connection area 232 and the protrusion 214 of the first current collector 23.

[0277] According to some embodiments of this application, as shown in Figures 6, 7 and 8, the Vickers hardness value of the main body region 2141a is 70 to 200.

[0278] For example, the Vickers hardness of the main body region 2141a can be 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 160, 170, 180, 190 or 200, etc.

[0279] In this embodiment, the Vickers hardness of the main body region 2141a is 70 to 200. On the one hand, by setting the Vickers hardness of the main body region 2141a to be greater than or equal to 70, the overall structural strength of the protrusion 214 is improved, which helps to alleviate the phenomenon of cracking or damage of the protrusion 214 during use, thereby improving the stability of the cylindrical battery cell 20. On the other hand, by setting the Vickers hardness of the main body region 2141a to be less than or equal to 200, the molding and processing difficulty of the protrusion 214 is reduced, and the manufacturing cost of the cylindrical battery cell 20 is reduced.

[0280] According to some embodiments of this application, as shown in Figures 6 and 8, the second connection area 2141b includes two first sub-connection areas, which are located on both sides of the connection portion 24 in the width direction of the connection portion 24.

[0281] The width direction of the connecting part 24 is perpendicular to the extension direction of the connecting part 24. If the connecting part 24 is a strip structure, the two first sub-connecting areas are located on both sides in a direction perpendicular to the length direction of the connecting part 24. If the connecting part 24 is an arc-shaped structure or a ring structure, the two first sub-connecting areas are located on the inner and outer peripheral sides of the connecting part 24.

[0282] For example, in this embodiment of the application, the connecting portion 24 is a structure that is partially embedded in the second connecting area 2141b, such that a portion of the second connecting area 2141b surrounds the outside of the connecting portion 24.

[0283] It should be noted that, referring to Figures 6 and 8, in the embodiment where the connecting part 24 does not penetrate the second connecting area 2141b along the first direction X, that is, the connecting part 24 is a structure in which one end in the first direction X is inserted into the second connecting area 2141b. Correspondingly, the second connecting area 2141b also includes a second sub-connecting area, which is located on one side of the connecting part 24 in the first direction X, and the second sub-connecting area is connected to both first sub-connecting areas.

[0284] In this embodiment, the second connection area 2141b has two first sub-connection areas located on both sides of the connection portion 24 in the width direction of the connection portion 24, so that each side of the connection portion 24 is connected to the main body area 2141a through a first sub-connection area. This allows the second connection area 2141b to play a certain buffering role on both sides of the connection portion 24, which helps to further alleviate the rigid tension between the first connection area 232 and the protrusion 214 of the first current collector 23, thereby further reducing the phenomenon of weld detachment between the first connection area 232 and the protrusion 214 of the first current collector 23, and further reducing the risk of connection failure between the electrode assembly 22 and the side wall 213 of the outer shell 21.

[0285] According to some embodiments of this application, referring to FIG6, a first connecting region 232 and a second connecting region 2141b are stacked along a first direction X, and a connecting portion 24 connects the first connecting region 232 and the second connecting region 2141b. Along the first direction X, the second connecting region 2141b has a first surface 2141k facing the first connecting region 232. Within the first surface 2141k, the minimum distance between the orthographic projection of the portion of the connecting portion 24 embedded in the second connecting region 2141b and the outer edge of the first surface 2141k is L1, which satisfies 0.05mm≤L1≤2.5mm.

[0286] The first connection area 232 is the area where the first current collecting member 23 is welded to the first connection wall 2141 of the protrusion 214. For example, the first connection area 232 and the second connection area 2141b are stacked along the first direction X.

[0287] The connecting part 24 connects the first connecting area 232 and the second connecting area 2141b. That is, the second connecting area 2141b and the first connecting area 232 are welded together to form the connecting part 24, such that a portion of the connecting part 24 is embedded in the second connecting area 2141b and a portion of the connecting part 24 is embedded in the first connecting area 232.

[0288] The second connection region 2141b has a first surface 2141k facing the first connection region 232. The first surface 2141k is the surface of the second connection region 2141b facing the first connection region 232 in the first direction X, and is also the surface of the second connection region 2141b that abuts against the first connection region 232 in the first direction X.

[0289] For example, within the first table, the minimum distance L1 between the orthographic projection of the portion of the connecting part 24 embedded in the second connecting area 2141b and the outer edge of the first surface 2141k can be 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, or 0. 28mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm or 2.5mm, etc.

[0290] In this embodiment, the minimum distance between the orthographic projection of the portion of the connecting part 24 embedded in the second connecting area 2141b onto the first surface 2141k and the outer edge of the first surface 2141k is 0.05mm to 2.5mm. This makes the minimum size of the second connecting area 2141b between the connecting part 24 and the main body area 2141a 0.05mm to 2.5mm. On the one hand, by setting the minimum distance between the orthographic projection of the portion of the connecting part 24 embedded in the second connecting area 2141b onto the first surface 2141k and the outer edge of the first surface 2141k to be greater than or equal to 0.05mm, the size of the buffer area between the connecting part 24 and the main body area 2141a can be increased, which is beneficial to improving the buffering effect of the second connecting area 2141b between the connecting part 24 and the main body area 2141a. As a result, the rigid tension between the first connecting area 232 and the protrusion 214 of the first current collector 23 can be further alleviated, thereby further reducing the phenomenon of weld detachment between the first connecting area 232 and the protrusion 214 of the first current collector 23. On the other hand, by setting the minimum distance between the orthographic projection of the part of the connecting portion 24 embedded in the second connecting area 2141b in the first surface 2141k and the outer edge of the first surface 2141k to be less than or equal to 2.5mm, the phenomenon of weakening of the overall structural strength of the first connecting wall 2141 of the protrusion 214 due to excessive space occupied by the second connecting area 2141b can be alleviated. Thus, while realizing the buffering effect of the second connecting area 2141b between the connecting portion 24 and the main body area 2141a, the overall structural strength of the protrusion 214 can also be improved.

[0291] According to some embodiments of this application, referring to Figures 4, 6, and 7, a groove 2132 is formed on the side of the sidewall 213 facing away from the electrode assembly 22 and corresponding to the position of the protrusion 214. The protrusion 214 includes two first connecting walls 2141 and a second connecting wall 2142. The two first connecting walls 2141 are arranged opposite to each other along a first direction X. The groove 2132 is formed between the two first connecting walls 2141. The two ends of the second connecting wall 2142 in the first direction X are respectively connected to the two first connecting walls 2141. One of the two first connecting walls 2141 is welded to the first connecting area 232 to form a connecting portion 24.

[0292] For example, the protrusion 214 formed on the side of the sidewall 213 facing the electrode assembly 22 is a structure formed by a stamping process, so that the protrusion 214 is formed on the side of the sidewall 213 facing the electrode assembly 22, and a groove 2132 is formed on the side of the sidewall 213 facing away from the electrode assembly 22 at the position corresponding to the protrusion 214. Of course, the forming method of the protrusion 214 formed on the side of the sidewall 213 facing the electrode assembly 22 is not limited to this. In other embodiments, the protrusion 214 formed on the side of the sidewall 213 facing the electrode assembly 22 can also be formed by a processing process such as casting.

[0293] It should be noted that in the embodiment where the protrusion 214 is an annular structure extending circumferentially along the sidewall 213, the corresponding groove 2132 is also an annular groove structure extending circumferentially along the sidewall 213. Correspondingly, the two first connecting walls 2141 are the two groove sidewalls 213 opposite to each other in the first direction X of the groove 2132, while the second connecting wall 2142 is the bottom wall of the groove 2132, such that the second connecting wall 2142 connects between the two first connecting walls 2141 in the first direction X.

[0294] Optionally, the first connection area 232 of the first current collector 23 can be a structure in which the protrusion 214 is welded to a first connection wall 2141 of the cylindrical battery cell 20 facing the electrode assembly 22 in the axial direction. That is, the first connection area 232 of the first current collector 23 is welded to the side of the protrusion 214 facing the electrode assembly 22 in the axial direction of the cylindrical battery cell 20. Of course, the first connection area 232 of the first current collector 23 can also be a structure in which the protrusion 214 is welded to a first connection wall 2141 of the cylindrical battery cell 20 away from the electrode assembly 22 in the axial direction. That is, the first connection area 232 of the first current collector 23 is welded to the side of the protrusion 214 away from the electrode assembly 22 in the axial direction of the cylindrical battery cell 20.

[0295] For example, in Figures 6 and 7, the first connection area 232 of the first current collector 23 is welded to the protrusion 214 on a first connection wall 2141 of the cylindrical battery cell 20 away from the electrode assembly 22 in the axial direction. That is, the first connection area 232 of the first current collector 23 is welded to the protrusion 214 on the side of the cylindrical battery cell 20 away from the electrode assembly 22 in the axial direction.

[0296] In this embodiment, by forming a groove 2132 on the side of the sidewall 213 facing away from the electrode assembly 22 and at the position corresponding to the protrusion 214, the protrusion 214 formed on the side of the sidewall 213 facing the electrode assembly 22 can be formed by stamping. This allows for the formation of a protrusion 214 on the side of the sidewall 213 facing the electrode assembly 22, and a groove 2132 on the other side at the position corresponding to the protrusion 214. This structure of the cylindrical battery cell 20 reduces the difficulty of forming the protrusion 214 on the sidewall 213 facing the electrode assembly 22, thus improving the production efficiency of the cylindrical battery cell 20. The surface can make the interior of the protrusion 214 hollow, thereby reducing the power required to weld the first connecting wall 2141 of the protrusion 214 to the first connecting area 232 of the first current collector 23. This helps to reduce the welding difficulty between the first connecting wall 2141 of the protrusion 214 and the first connecting area 232 of the first current collector 23, and also allows the protrusion 214 to have the ability to deform elastically. This helps to further alleviate the rigid tension between the first connecting area 232 of the first current collector 23 and the protrusion 214, thereby reducing the risk of weld detachment between the first connecting area 232 of the first current collector 23 and the protrusion 214.

[0297] According to some embodiments of this application, referring to Figures 6 and 7, the wall thickness of a portion of the protrusion 214 is less than the wall thickness of other portions of the protrusion 214. That is, the protrusion 214 is a structure with locally thinned areas, and similarly, the groove wall of the corresponding groove 2132 is a structure with locally thinned areas.

[0298] In this embodiment, by setting the wall thickness of a portion of the protrusion 214 to be less than the wall thickness of other portions of the protrusion 214, the groove wall of the groove 2132 is locally thinned and forms a thinned area, thereby improving the elastic deformation capability of the protrusion 214. This helps to further alleviate the rigid tension between the first connecting area 232 of the first current collector 23 and the protrusion 214, thereby reducing the risk of weld detachment between the first connecting area 232 of the first current collector 23 and the protrusion 214.

[0299] According to some embodiments of this application, please continue to refer to Figures 6 and 7, at least a portion of the wall thickness of the protrusion 214 is less than the wall thickness of the sidewall 213.

[0300] The protrusion 214 may have an overall wall thickness that is less than the wall thickness of the side wall 213, that is, the wall thickness of the entire groove wall of the groove 2132 is less than the wall thickness of the side wall 213. Correspondingly, the wall thickness of the two first connecting walls 2141 and the wall thickness of the second connecting wall 2142 of the protrusion 214 are both less than the wall thickness of the side wall 213. Of course, the protrusion 214 may also have only a portion of its wall thickness that is less than the wall thickness of the side wall 213, that is, the wall thickness of a portion of the groove wall of the groove 2132 is less than the wall thickness of the side wall 213. Correspondingly, the wall thickness of the first connecting wall 2141 of the protrusion 214 may be less than the wall thickness of the side wall 213, or the wall thickness of the second connecting wall 2142 of the protrusion 214 may be less than the wall thickness of the side wall 213.

[0301] For example, in Figure 7, the overall wall thickness of the protrusion 214 is less than the wall thickness of the side wall 213, that is, the wall thickness of the two first connecting walls 2141 and the second connecting wall 2142 of the protrusion 214 is less than the wall thickness of the side wall 213.

[0302] In this embodiment, by setting the wall thickness of at least a portion of the protrusion 214 to be less than the wall thickness of the sidewall 213, the structural strength of the sidewall 213 is improved while the elastic deformation capability of the protrusion 214 is enhanced, thereby further alleviating the rigid tension between the first connection area 232 of the first current collector 23 and the protrusion 214, and reducing the risk of weld detachment between the first connection area 232 of the first current collector 23 and the protrusion 214.

[0303] According to some embodiments of this application, referring to Figures 5 and 6, the protrusion 214 is an annular structure extending circumferentially along the sidewall 213, and the first connecting wall 2141 is also an annular structure extending circumferentially along the sidewall 213. That is, the protrusion 214 is an annular structure coaxial with the cylindrical battery cell 20, and the first connecting wall 2141 of the protrusion 214 is also an annular structure coaxial with the cylindrical battery cell 20.

[0304] In this embodiment, by setting the protrusion 214 as an annular structure extending circumferentially along the sidewall 213, the first connecting wall 2141 of the protrusion 214 is also an annular structure extending circumferentially along the sidewall 213. This allows the first connecting wall 2141 of the protrusion 214 to be welded to the first connecting area 232 of the first current collector 23 at any position circumferentially along the sidewall 213. This facilitates the welding connection between the first connecting area 232 of the first current collector 23 and the first connecting wall 2141 of the protrusion 214. After assembling the first current collector 23 into the housing, the welding assembly of the first connecting area 232 and the first connecting wall 2141 of the protrusion 214 can be achieved without rotating or adjusting the position of the first current collector 23. This further reduces the welding difficulty between the first connecting area 232 of the first current collector 23 and the first connecting wall 2141 of the protrusion 214, thereby effectively improving the assembly efficiency of the cylindrical battery cell 20.

[0305] In some embodiments, the connecting portion 24 extends circumferentially along the sidewall 213. That is, the connecting portion 24 formed by welding the first connecting area 232 of the first current collector 23 and the first connecting wall 2141 of the protrusion 214 is an arc-shaped structure or an annular structure extending circumferentially along the sidewall 213.

[0306] For example, in the embodiments of this application, the first connecting area 232 of the first current collector 23 is an arc-shaped structure extending circumferentially along the side wall 213. Correspondingly, the connecting part 24 formed by welding the first connecting area 232 of the first current collector 23 and the first connecting wall 2141 of the protrusion 214 is also an arc-shaped structure extending circumferentially along the side wall 213.

[0307] In this embodiment, by setting the connecting portion 24 to be aligned with the extending direction of the first connecting wall 2141 of the protrusion 214, the area of ​​the region where the first connecting area 232 of the first current collector 23 and the first connecting wall 2141 are welded together can be increased. Furthermore, the first connecting wall 2141 of the protrusion 214 can be welded to the first connecting area 232 of the first current collector 23 at multiple positions in the circumferential direction of the side wall 213. On the one hand, this can further improve the connection stability and reliability between the first connecting area 232 of the first current collector 23 and the protrusion 214, thereby reducing the risk of weld detachment between the first connecting area 232 of the first current collector 23 and the protrusion 214 during use. On the other hand, it can improve the flow area and flow balance between the first current collector 23 and the protrusion 214, thereby reducing the risk of local temperature rise in the protrusion 214.

[0308] In some embodiments, the first connecting wall 2141 of the protrusion 214 is formed with a plurality of second connecting regions 2141b, the plurality of second connecting regions 2141b being arranged at circumferential intervals along the side wall 213, and each second connecting region 2141b being connected to a connecting portion 24.

[0309] The protrusion 214 has multiple second connection areas 2141b, and each second connection area 2141b is connected to a connection part 24. That is, the protrusion 214 is welded to the first connection area 232 of the first current collector 23 at multiple positions in the circumferential direction of the side wall 213, so that the first connection area 232 of the first current collector 23 and the first connection wall 2141 of the protrusion 214 are welded to form multiple connection parts 24, and each connection part 24 is a structure that is connected to the main body area 2141a through a second connection area 2141b. In this embodiment, the first current collector 23 is provided with a plurality of first connection areas 232. The plurality of first connection areas 232 are welded to the first connection wall 2141 of the protrusion 214 to form a plurality of connection portions 24. It should be noted that each first connection area 232 may be welded to the first connection wall 2141 of the protrusion 214 to form a plurality of connection portions 24, or each first connection area 232 may be welded to the first connection wall 2141 of the protrusion 214 to form only one connection portion 24.

[0310] Multiple second connection areas 2141b are arranged at intervals along the circumference of the sidewall 213. Correspondingly, multiple connection parts 24 formed by welding multiple first connection areas 232 of the first current collector 23 to the first connection wall 2141 of the protrusion 214 are also arranged at intervals along the circumference of the sidewall 213. Correspondingly, multiple first connection areas 232 are also arranged at intervals along the circumference of the sidewall 213.

[0311] In this embodiment, a plurality of second connection areas 2141b are formed on the protrusion 214, arranged circumferentially along the sidewall 213, and each second connection area 2141b is connected to a corresponding connection part 24, so that the first connection area 232 of the first current collector 23 and the first connection wall 2141 of the protrusion 214 are welded together to form a plurality of connection parts 24 arranged circumferentially along the sidewall 213, and each connection part 24 is connected to the main body area 2141a through a second connection area 2141b. This can further improve the connection stability and reliability between the first connection area 232 of the first current collector 23 and the protrusion 214, which is conducive to further alleviating the phenomenon of weld detachment between the first connection area 232 of the first current collector 23 and the protrusion 214. On the other hand, it can further increase the flow area between the first connection area 232 of the first current collector 23 and the protrusion 214, so as to further improve the flow capacity between the first current collector 23 and the protrusion 214.

[0312] According to some embodiments of this application, as shown in Figures 4, 5 and 6, the electrode assembly 22 may further include a main body 221. Along the axial direction of the cylindrical battery cell 20, the main body 221 is located on the side of the protrusion 214 away from the first wall 211. The first tab 222 is connected to the end of the main body 221 facing the first wall 211, and the body region 231 is located between the electrode assembly 22 and the protrusion 214.

[0313] The main body 221, the first tab 222, and the first current collector 23 are arranged sequentially along the axial direction of the cylindrical battery cell 20. The first tab 222 is connected between the main body 221 and the main body region 2141a of the first current collector 23 in the axial direction of the cylindrical battery cell 20. The main body region 2141a is disposed between the protrusion 214 and the electrode assembly 22 in the axial direction of the cylindrical battery cell 20 to support the electrode assembly 22. Correspondingly, the first connecting region 232 is disposed on the side of the main body region 2141a away from the electrode assembly 22 in the axial direction of the cylindrical battery cell 20 and is welded to the first connecting wall 2141 of the protrusion 214.

[0314] In this embodiment, the main body 221 of the electrode assembly 22 is disposed on the side of the protrusion 214 away from the first wall 211 along the axial direction of the cylindrical battery cell 20, and the body region 231 is disposed between the electrode assembly 22 and the protrusion 214, so that the body region 231 of the first current collector 23 can provide a certain support for the main body 221 of the electrode assembly 22 and resist the expansion of the electrode assembly 22 during use. In this embodiment, by setting the first tab 222 to be connected to the end of the main body 221 facing the first wall 211, and setting the body region 231 of the first current collector 23 on the side of the first tab 222 away from the main body 221, the main body 221, the first tab 222 and the body region 231 are arranged sequentially along the axial direction of the cylindrical battery cell 20, thereby reducing the assembly difficulty between the first tab 222 and the body region 231 of the first current collector 23, which is beneficial to improving the production efficiency of the cylindrical battery cell 20 and optimizing the production process of the cylindrical battery cell 20.

[0315] According to some embodiments of this application, referring to FIG6, and further referring to FIGS. 9 and 10, FIG9 is a structural schematic diagram of the first current collector 23 of the cylindrical battery cell 20 provided in some embodiments of this application, and FIG10 is a front view of the first current collector 23 of the cylindrical battery cell 20 provided in some embodiments of this application along the axial direction of the cylindrical battery cell 20. The first connecting region 232 is located on the side of the body region 231 facing the first wall 211 along the axial direction of the cylindrical battery cell 20. The first current collector 23 also includes a transition region 233, which connects the body region 231 and the first connecting region 232. The transition region 233 is configured to deform when the body region 231 and the first connecting region 232 move closer or further apart along the axial direction of the cylindrical battery cell 20.

[0316] The transition region 233 is a structure connecting the main body region 231 and the first connecting region 232. The transition region 233 is configured to deform when the main body region 231 and the first connecting region 232 move closer or further apart along the axial direction of the cylindrical battery cell 20. That is, when the first current collector 23 is compressed or stretched along the axial direction of the cylindrical battery cell 20, the transition region 233 can deform when the main body region 231 and the first connecting region 232 move closer or further apart. It should be noted that the deformation of the transition region 233 can be either elastic or plastic.

[0317] Optionally, in Figure 9, the first current collection component 23 is provided with a plurality of first connection areas 232 and a plurality of transition areas 233. The plurality of transition areas 233 are arranged circumferentially along the sidewall 213 and are all connected to the main body area 231. Correspondingly, the plurality of first connection areas 232 are arranged circumferentially along the sidewall 213. Each first connection area 232 is connected to the main body area 231 through a transition area 233. Each first connection area 232 is welded to the first connection wall 2141 of the protrusion 214 to form a connection part 24. It should be noted that the connection part 24 formed by welding each first connection area 232 to the first connection wall 2141 of the protrusion 214 can be one or more.

[0318] For example, the first connection area 232 is an arc-shaped structure extending circumferentially along the side wall 213. When there are multiple connection parts 24 formed by welding each first connection area 232 to the first connection wall 2141 of the protrusion 214, the multiple connection parts 24 on the same first connection area 232 are arranged circumferentially on the first connection area 232.

[0319] For example, in FIG10, the first current collector 23 is provided with four first connection areas 232 and four transition areas 233, and each first connection area 232 is connected to the body area 231 through a transition area 233. Of course, in other embodiments, the number of first connection areas 232 of the first current collector 23 may also be two, three, five or six, etc.

[0320] Optionally, the body area 231, the first connecting area 232, and the transition area 233 of the first current collector 23 can be an integrally formed structure or a separate but connected structure. For example, in FIG9, the body area 231, the first connecting area 232, and the transition area 233 of the first current collector 23 are an integral structure formed by integral forming processes such as stamping and cutting.

[0321] In this embodiment, the first current collector 23 is also provided with a transition region 233 connecting the body region 231 and the first connection region 232. By setting the transition region 233 to be deformable when the body region 231 and the first connection region 232 move closer or further apart along the axial direction of the cylindrical battery cell 20, the transition region 233 can play a certain buffering role between the body region 231 and the first connection region 232. This can alleviate the rigid tension between the body region 231 and the first connection region 232, between the body region 231 and the first tab 222, and between the first connection region 232 and the protrusion 214 during the shaking or displacement of the electrode assembly 22. This is beneficial to further reduce the risk of connection failure between the body region 231 and the first tab 222 and between the first connection region 232 and the protrusion 214, and also helps to reduce the phenomenon of the first current collector 23 being damaged by tension.

[0322] According to some embodiments of this application, as shown in FIG9, the transition region 233 is bent to form a plurality of bent segments 2331, the plurality of bent segments 2331 are connected in sequence, and the bent segments 2331 located at both ends of the plurality of bent segments 2331 are respectively connected to the body region 231 and the first connection region 232.

[0323] The transition zone 233 is bent to form multiple bent segments 2331, which are connected in sequence. In other words, the transition zone 233 is a structure with local bending, which results in the formation of multiple bent segments 2331 connected in sequence. Each pair of adjacent bent segments 2331 is set at an acute angle, a right angle, or an obtuse angle.

[0324] For example, in Figure 9, the transition region 233 is bent to form three bent segments 2331 connected in sequence, and the two bent segments 2331 located at both ends of the three bent segments 2331 are connected to the body region 231 and the first connecting region 232 respectively. Of course, in other embodiments, the number of bent segments 2331 formed by the bending of the transition region 233 can also be two, four, five or six, etc.

[0325] In this embodiment, by setting the transition region 233 as a structure of bending to form a plurality of sequentially connected bent segments 2331, and the bent segments 2331 located at both ends of the plurality of bent segments 2331 being connected to the body region 231 and the first connecting region 232 respectively, the deformation capacity of the transition region 233 when the body region 231 and the first connecting region 232 approach or move away from each other along the axial direction of the cylindrical battery cell 20 can be increased, thereby further improving the buffering effect of the transition region 233 between the body region 231 and the first connecting region 232, and further reducing the phenomenon of rigid pulling between the body region 231 and the first connecting region 232, between the body region 231 and the first tab 222, and between the first connecting region 232 and the protrusion 214.

[0326] According to some embodiments of this application, as shown in Figures 6, 9 and 10, a pressure relief component is provided on the first wall 211, which is configured to release the internal pressure of the cylindrical battery cell 20.

[0327] For example, the pressure relief component and the first wall 211 are integrally formed, that is, the pressure relief component is part of the first wall 211.

[0328] In this embodiment, by providing a pressure relief component on the first wall 211 for relieving the internal pressure of the cylindrical battery cell 20, the cylindrical battery cell 20 can still be depressurized through the pressure relief component when thermal runaway occurs, which helps to reduce the risk of explosion of the cylindrical battery cell 20 during use and improves the reliability of the cylindrical battery cell 20.

[0329] According to some embodiments of this application, referring to Figures 6 and 10, in a projection plane perpendicular to the axial direction of the cylindrical battery cell 20, the orthographic projections of the body region 231 and the first connecting region 232 form an exhaust gap 234 in the radial direction of the cylindrical battery cell 20. That is, in a projection plane perpendicular to the axial direction of the cylindrical battery cell 20, the orthographic projections of the first connecting region 232 and the body region 231 are spaced apart in the radial direction of the cylindrical battery cell 20.

[0330] In this embodiment, in the projection plane perpendicular to the axis of the cylindrical battery cell 20, the orthographic projection of the first connection area 232 and the orthographic projection of the body area 231 are configured to form an exhaust gap 234 in the radial direction of the cylindrical battery cell 20. This allows the thermal runaway gas inside the cylindrical battery cell 20 to enter the side of the first current collector 23 facing the first wall 211 through the exhaust gap 234 between the first connection area 232 and the body area 231, and then be released through the pressure relief component. This helps to reduce the obstruction of the exhaust path inside the cylindrical battery cell 20 by the first current collector 23, thereby improving the smoothness of the internal exhaust and the pressure relief rate of the cylindrical battery cell 20.

[0331] In some embodiments, as shown in Figures 6 and 10, the pressure relief component is provided with a pressure relief groove 2111, at least a portion of the projection of the pressure relief groove 2111 onto the axial direction of the cylindrical battery cell 20 is located within the exhaust gap 234.

[0332] In the embodiment where the pressure relief component and the first wall 211 are integrally formed, the pressure relief groove 2111 is a structure provided on the first wall 211. At least a portion of the projection of the pressure relief groove 2111 onto the cylindrical battery cell 20 in the axial direction is located within the exhaust gap 234. That is, at least a portion of the area of ​​the first wall 211 where the pressure relief groove 2111 is provided is a structure provided on the axial direction of the cylindrical battery cell 20 corresponding to the exhaust gap 234 between the first connecting area 232 and the body area 231.

[0333] In this embodiment, by setting the pressure relief groove 2111 on the pressure relief component to a structure in which at least a portion of its projection on the axial direction of the cylindrical battery cell 20 is located within the exhaust gap 234, the pressure relief groove 2111 is configured such that at least a portion of its axial direction of the cylindrical battery cell 20 corresponds to the exhaust gap 234 between the first connection area 232 and the body area 231. This further improves the smoothness of internal exhaust and pressure relief of the cylindrical battery cell 20, thereby increasing the pressure relief rate of the cylindrical battery cell 20. Consequently, it reduces the risk of fire and explosion caused by untimely pressure relief of the cylindrical battery cell 20, thereby improving the reliability of the cylindrical battery cell 20.

[0334] According to some embodiments of this application, referring to Figures 9 and 10, in a projection plane perpendicular to the axial direction of the cylindrical battery cell 20, the orthographic projection of the first connecting region 232 extends circumferentially along the sidewall 213 and is located on the periphery of the orthographic projection of the body region 231. The orthographic projections of the first connecting region 232 and the body region 231 are arranged radially spaced apart in the cylindrical battery cell 20. The diameter of the orthographic projection of the outer edge of the first connecting region 232 is d, and the orthographic projection of the transition region 233 extends radially along the cylindrical battery cell 20 with a length of L2, satisfying that 1 / 15 ≤ L2 / d ≤ 1 / 3.

[0335] In the projection plane along the axial direction of the cylindrical battery cell 20, the orthographic projection of the first connection area 232 extends along the circumference of the cylindrical battery cell 20 and is located on the periphery of the orthographic projection of the body area 231. That is, the orthographic projection of the first connection area 232 along the axial direction of the cylindrical battery cell 20 is an arc-shaped structure or annular structure extending along the circumference of the cylindrical battery cell 20, and the first connection area 232 is arranged around the body area 231. For example, in FIG10, the first current collector 23 is provided with a plurality of first connection areas 232, each first connection area 232 is connected to the body area 231 through a transition area 233, the plurality of first connection areas 232 are arranged at intervals along the circumference of the cylindrical battery cell 20 and are arranged around the body area 231, and each first connection area 232 is an arc-shaped structure extending along the circumference of the cylindrical battery cell 20. Correspondingly, in the projection plane perpendicular to the axis of the cylindrical battery cell 20, the diameter d of the orthographic projection of the outer edge of the first connection area 232 is the diameter of the circle in which the orthographic projection of the outer edge of the first connection area 232 is located.

[0336] In the projection plane perpendicular to the axis of the cylindrical battery cell 20, the orthographic projection of the first connecting region 232 and the orthographic projection of the body region 231 are arranged at intervals in the radial direction of the cylindrical battery cell 20, and the orthographic projection of the transition region 233 extends radially along the cylindrical battery cell 20. That is, the orthographic projection of the first connecting region 232 in the axial direction of the cylindrical battery cell 20 and the orthographic projection of the body region 231 in the axial direction of the cylindrical battery cell 20 are arranged at intervals in the radial direction of the cylindrical battery cell 20, and the transition region 233 connects the first connecting region 232 and the body region 231 in the radial direction of the cylindrical battery cell 20.

[0337] Optionally, in the projection plane perpendicular to the axis of the cylindrical battery cell 20, the ratio of the length L2 of the orthographic projection of the transition region 233 onto the radial direction of the cylindrical battery cell 20 to the diameter d of the orthographic projection of the outer edge of the first connection region 232 can be 1 / 15, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 1 / 7, 0.15, 0.16, 0.18, 0.2, 0.22, 0.23, 0.25, 0.26, 0.28, 0.3, 0.31, 0.32, or 1 / 3, etc.

[0338] In this embodiment, in the projection plane perpendicular to the axial direction of the cylindrical battery cell 20, the orthographic projections of the first connecting region 232 and the main body region 231 are arranged at intervals in the radial direction of the cylindrical battery cell 20. Furthermore, the ratio of the length of the transition region 233 of the first current collector 23 in the radial direction of the cylindrical battery cell 20 to the diameter of the orthographic projection of the outer edge of the first connecting region 232 is set to 1 / 15 to 1 / 3. This alleviates the problem of the transition region 233 occupying too small a size in the radial direction of the cylindrical battery cell 20, and helps to expand the exhaust space between the first connecting region 232 and the main body region 231. This allows the thermal runaway gas inside the cylindrical battery cell 20 to pass through the exhaust space between the first connecting region 232 and the main body region 231. The pressure relief components on the first wall 211 release pressure, thereby improving the internal venting smoothness of the cylindrical battery cell 20 and increasing the pressure relief rate of the cylindrical battery cell 20. This reduces the risk of the cylindrical battery cell 20 bursting or exploding due to untimely pressure relief. On the other hand, it alleviates the problem of insufficient support strength between the body area 231 and the first connection area 232 caused by the excessive size of the transition area 233 in the radial direction of the cylindrical battery cell 20. This effectively improves the support effect of the first current collector 23 on the electrode assembly 22 and the effect of resisting the expansion of the electrode assembly 22 during use, thereby alleviating the phenomenon of excessive expansion or displacement of the electrode assembly 22. This is conducive to improving the stability and reliability of the cylindrical battery cell 20 in use.

[0339] In some embodiments, as shown in Figure 10, 1 / 7 ≤ L2 / d ≤ 1 / 4.

[0340] In this embodiment, in the projection plane perpendicular to the axial direction of the cylindrical battery cell 20, by further setting the ratio of the length of the transition region 233 of the first current collector 23 in the radial direction of the cylindrical battery cell 20 to the diameter of the orthographic projection of the outer edge of the first connecting region 232 to 1 / 7 to 1 / 4, the phenomenon of the transition region 233 occupying too small a size in the radial direction of the cylindrical battery cell 20 can be further alleviated. This is beneficial to further expand the exhaust space between the first connecting region 232 and the body region 231, so that the thermal runaway gas inside the cylindrical battery cell 20 can be released through the pressure relief component on the first wall 211 after passing through the exhaust space between the first connecting region 232 and the body region 231, thereby further improving the cylindrical battery cell's thermal runaway gas distribution. The smooth internal venting of the single cell 20 further improves the depressurization rate of the cylindrical battery cell 20, thereby reducing the risk of bursting or exploding due to untimely depressurization. On the other hand, it can further alleviate the phenomenon that the transition zone 233 occupies too large a size in the radial direction of the cylindrical battery cell 20, resulting in insufficient support strength between the body region 231 and the first connection region 232. This can further improve the support effect of the first current collector 23 on the electrode assembly 22 and the effect of resisting the expansion of the electrode assembly 22 during use, thereby further alleviating the phenomenon of excessive expansion or displacement of the electrode assembly 22, and thus helping to further improve the stability and reliability of the cylindrical battery cell 20 in use.

[0341] In some embodiments, please continue to refer to Figure 10, 3mm≤L2≤15mm.

[0342] Optionally, in the projection plane perpendicular to the axis of the cylindrical battery cell 20, the length L2 of the orthographic projection of the transition zone 233 onto the radial direction of the cylindrical battery cell 20 can be 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, 10.5mm, 11mm, 11.5mm, 12mm, 12.5mm, 13mm, 13.5mm, 14mm, 14.5mm, or 15mm, etc.

[0343] In this embodiment, in the projection plane perpendicular to the axial direction of the cylindrical battery cell 20, by setting the length of the transition region 233 of the first current collector 23 in the radial direction of the cylindrical battery cell 20 to 3mm to 15mm, on the one hand, setting the length of the transition region 233 in the radial direction of the cylindrical battery cell 20 to be greater than or equal to 3mm can increase the exhaust space between the first connection region 232 and the body region 231, so that the thermal runaway gas inside the cylindrical battery cell 20 can pass through the exhaust space between the first connection region 232 and the body region 231 and then through the first wall 211. The pressure relief component releases pressure, which helps to improve the smoothness of internal venting of the cylindrical battery cell 20. On the other hand, setting the length of the transition zone 233 in the radial direction of the cylindrical battery cell 20 to less than or equal to 15mm can alleviate the phenomenon that the transition zone 233 is too long and therefore the support strength of the transition zone 233 between the body region 231 and the first connection region 232 is insufficient. This helps to improve the support effect of the first current collector 23 on the electrode assembly 22 and the effect of resisting the expansion of the electrode assembly 22 during use, so as to further alleviate the phenomenon of excessive expansion or displacement of the electrode assembly 22.

[0344] According to some embodiments of this application, and in conjunction with Figures 6 and 10, the thickness of the transition region 233 is T, and the width of the orthographic projection of the transition region 233 in the direction perpendicular to its extension direction in the projection plane perpendicular to the axial direction of the cylindrical battery cell 20 is W, satisfying 0.3 mm. 2 ≤W×T≤8mm 2 .

[0345] Wherein, the thickness of the transition region 233 is T, which is the thickness of the transition region 233 at any position. In the embodiment where the transition region 233 includes a plurality of sequentially connected bending segments 2331, the thickness of each bending segment 2331 is T.

[0346] Alternatively, the product of W and T can be 0.3 mm. 2 0.4mm 2 0.5mm 2 0.6mm 2 0.7mm 2 0.8mm 2 0.9mm 2 1mm 2 1.5mm 2 2mm 2 2.5mm 2 3mm 2 3.5mm 2 4mm 2 4.5mm 2 5mm 2 5.5mm 2 6mm2 6.5mm 2 7mm 2 7.5mm 2 Or 8mm 2 wait.

[0347] In this embodiment, the product of W and T is set to 0.3mm. 2 up to 8mm 2 On the one hand, the product of W and T is set to be less than or equal to 8mm. 2 This design mitigates the problem of excessive deformation difficulty in the transition region 233 caused by excessively large W and T values. It enhances the ability of the transition region 233 to deform when the body region 231 and the first connecting region 232 move closer or further apart along the axial direction of the cylindrical battery cell 20. This allows the transition region 233 to act as a better buffer between the body region 231 and the first connecting region 232. Consequently, it reduces rigid tension between the body region 231 and the first connecting region 232, between the body region 231 and the first tab 222, and between the first connecting region 232 and the protrusion 214 during periods of shaking or displacement of the electrode assembly 22. Furthermore, setting the product of W and T to be greater than or equal to 0.3 mm... 2 It can improve the structural strength of the transition zone 233, which helps to alleviate the phenomenon of insufficient support strength of the transition zone 233 between the body zone 231 and the first connection zone 232, so as to improve the support effect of the first current collector 23 on the electrode assembly 22 and the effect of resisting the expansion of the electrode assembly 22 during use. It can also improve the flow capacity of the transition zone 233, which helps to improve the flow guiding effect and flow guiding requirements of the first current collector 23.

[0348] According to some embodiments of this application, referring to Figures 9 and 10, in the projection plane perpendicular to the axial direction of the cylindrical battery cell 20, the width of the orthographic projection of the transition region 233 in the direction perpendicular to its extension direction is W, which satisfies 2mm≤W≤10mm.

[0349] Optionally, the width W of the projection of the transition region 233 onto the axial direction of the cylindrical battery cell 20 can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm or 10mm, etc.

[0350] In this embodiment, by setting the width of the projection of the transition region 233 of the first current collector 23 onto the axial direction of the cylindrical battery cell 20 to 2mm to 10mm, on the one hand, setting the width of the projection of the transition region 233 onto the axial direction of the cylindrical battery cell 20 to be greater than or equal to 2mm can improve the current carrying capacity of the transition region 233, thereby improving the current guiding effect of the first current collector 23, and on the other hand, it can improve the structural strength of the transition region 233, which helps to alleviate the phenomenon of insufficient support strength of the transition region 233 between the body region 231 and the first connection region 232, thereby improving the support effect of the first current collector 23 on the electrode assembly 22 and resisting the expansion of the electrode assembly 22 during use. On the other hand, setting the width of the projection of the transition region 233 on the axial direction of the cylindrical battery cell 20 to less than or equal to 10mm can effectively improve the ability of the transition region 233 to deform when the body region 231 and the first connection region 232 move closer or further apart along the axial direction of the cylindrical battery cell 20. This allows the transition region 233 to play a better buffering role between the body region 231 and the first connection region 232, thereby reducing the rigid pulling phenomenon between the body region 231 and the first connection region 232, between the body region 231 and the first tab 222, and between the first connection region 232 and the protrusion 214 when the electrode assembly 22 shakes or shifts during use.

[0351] In some embodiments, please continue to refer to Figure 10, 3mm≤W≤5mm.

[0352] In this embodiment, by further setting the width of the projection of the transition region 233 of the first current collector 23 onto the axial direction of the cylindrical battery cell 20 to 3mm to 5mm, on the one hand, setting the width of the projection of the transition region 233 onto the axial direction of the cylindrical battery cell 20 to be greater than or equal to 3mm can further improve the current carrying capacity of the transition region 233, thereby further improving the current guiding effect of the first current collector 23, and on the other hand, it can further improve the structural strength of the transition region 233, which is beneficial to further alleviate the phenomenon of insufficient support strength of the transition region 233 between the body region 231 and the first connection region 232, thereby further improving the support effect of the first current collector 23 on the electrode assembly 22 and its resistance to the electrode assembly 22. 2. The expansion effect during use. On the other hand, setting the width of the projection of the transition area 233 on the axial direction of the cylindrical battery cell 20 to less than or equal to 5mm can further enhance the ability of the transition area 233 to deform when the body area 231 and the first connection area 232 move closer or further apart along the axial direction of the cylindrical battery cell 20, so as to enhance the buffering effect of the transition area 233 between the body area 231 and the first connection area 232. Thus, when the electrode assembly 22 shakes or shifts during use, it can further reduce the rigid pulling phenomenon between the body area 231 and the first connection area 232, between the body area 231 and the first tab 222, and between the first connection area 232 and the protrusion 214.

[0353] According to some embodiments of this application, as shown in Figures 6 and 9, the thickness of the transition region 233 is T, which satisfies 0.15mm≤T≤0.8mm.

[0354] Optionally, the thickness T of the transition zone 233 can be 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm or 0.8mm, etc.

[0355] In this embodiment, by setting the thickness of the transition region 233 of the first current collector 23 to 0.15mm to 0.8mm, on the one hand, setting the thickness of the transition region 233 to be greater than or equal to 0.15mm can improve the flow capacity of the transition region 233, thereby improving the flow guiding effect of the first current collector 23, and can also improve the structural strength of the transition region 233. This helps to alleviate the phenomenon of insufficient support strength of the transition region 233 between the body region 231 and the first connection region 232, thereby improving the support effect of the first current collector 23 on the electrode assembly 22 and the effect of resisting the expansion of the electrode assembly 22 during use. On the other hand, setting the thickness of the transition region 233 to be less than or equal to 0.8mm It can effectively improve the ability of the transition area 233 to deform when the body area 231 and the first connection area 232 move closer or further apart along the axial direction of the cylindrical battery cell 20. This allows the transition area 233 to play a better buffering role between the body area 231 and the first connection area 232. As a result, when the electrode assembly 22 shakes or shifts during use, it can reduce the rigid pulling phenomenon between the body area 231 and the first connection area 232, between the body area 231 and the first tab 222, and between the first connection area 232 and the protrusion 214. It can also save the space occupied by the transition area 233 in the axial direction of the cylindrical battery cell 20, which is conducive to improving the internal space utilization of the cylindrical battery cell 20.

[0356] In some embodiments, please continue to refer to Figures 6 and 9, 0.3mm≤T≤0.5mm.

[0357] In this embodiment, by further setting the thickness of the transition region 233 of the first current collector 23 to 0.3mm to 0.5mm, on the one hand, setting the thickness of the transition region 233 to be greater than or equal to 0.3mm can further improve the flow capacity of the transition region 233, thereby further improving the flow guiding effect of the first current collector 23, and can further improve the structural strength of the transition region 233. This helps to further alleviate the phenomenon of insufficient support strength of the transition region 233 between the body region 231 and the first connection region 232, thereby further improving the support effect of the first current collector 23 on the electrode assembly 22 and the effect of resisting the expansion of the electrode assembly 22 during use. On the other hand, setting the thickness of the transition region 233 to be less than or equal to 0.3mm can improve the flow capacity of the transition region 233, thereby improving the flow guiding effect of the first current collector 23 on the electrode assembly 22 and the effect of resisting the expansion of the electrode assembly 22 during use. The 0.5mm thickness can further enhance the ability of the transition area 233 to deform when the body area 231 and the first connection area 232 move closer or further apart along the axial direction of the cylindrical battery cell 20. This further enhances the buffering effect of the transition area 233 between the body area 231 and the first connection area 232. As a result, when the electrode assembly 22 shakes or shifts during use, it can further reduce the rigid pulling phenomenon between the body area 231 and the first connection area 232, between the body area 231 and the first tab 222, and between the first connection area 232 and the protrusion 214. It can also further save the space occupied by the transition area 233 in the axial direction of the cylindrical battery cell 20, which is conducive to further improving the internal space utilization of the cylindrical battery cell 20.

[0358] According to some embodiments of this application, as shown in Figures 6 and 9, the thickness of the transition region 233 is less than the thickness of the body region 231.

[0359] In this embodiment, by setting the thickness of the transition region 233 to be less than the thickness of the body region 231, the manufacturing cost and difficulty of the first current collector 23 are reduced, while the ability of the transition region 233 to deform when the body region 231 and the first connection region 232 move closer or further apart along the axial direction of the cylindrical battery cell 20 is improved, so that the transition region 233 can play a better buffering role between the body region 231 and the first connection region 232.

[0360] According to some embodiments of this application, please continue to refer to Figures 6 and 9, the thickness of the transition region 233 is less than the thickness of the first connection region 232.

[0361] In this embodiment, by setting the thickness of the transition region 233 to be less than the thickness of the first connection region 232, the manufacturing cost and difficulty of the first current collector 23 are reduced, while the ability of the transition region 233 to deform when the body region 231 and the first connection region 232 move closer or further apart along the axial direction of the cylindrical battery cell 20 is improved, so that the transition region 233 can play a better buffering role between the body region 231 and the first connection region 232.

[0362] According to some embodiments of this application, referring to Figures 4, 5, and 6, the sidewall 213 and the second wall 212 are integrally formed, and the sidewall 213 and the second wall 212 enclose a receiving cavity, in which the electrode assembly 22 is received. Along the axial direction of the cylindrical battery cell 20, the end of the sidewall 213 away from the second wall 212 encloses an opening 2131, and the first wall 211 closes the opening 2131.

[0363] The second wall 212 and the first wall 211 are arranged opposite each other in the axial direction of the cylindrical battery cell 20. That is, the first wall 211 and the second wall 212 are the end walls of the outer shell 21 at both ends in the axial direction of the cylindrical battery cell 20, so that the first wall 211 and the second wall 212 are located at both ends of the side wall 213 in the axial direction of the cylindrical battery cell 20.

[0364] The side wall 213 and the second wall 212 are integrally formed, that is, the side wall 213 and the second wall 212 of the outer shell 21 are structures formed by an integral forming process, such as stamping or casting.

[0365] The first wall 211 closes the opening 2131, meaning that the first wall 211 is located at the opening 2131 of the side wall 213 at the end of the cylindrical battery cell 20 away from the second wall 212 in the axial direction and is sealed to the side wall 213. Optionally, the connection structure between the first wall 211 and the side wall 213 can be various, such as welding connection, snap-fit ​​connection, etc.

[0366] In this embodiment, by configuring the sidewall 213 of the outer casing 21 to form an opening 2131 at the end of the cylindrical battery cell 20 away from the second wall 212 in the axial direction, and the first wall 211 to close the opening 2131, the body area 231 of the first current collector 23 is arranged on the side of the electrode assembly 22 facing the opening 2131 in the axial direction of the cylindrical battery cell 20. This reduces the difficulty of assembling the body area 231 of the first current collector 23 between the electrode assembly 22 and the protrusion 214, and also reduces the welding difficulty between the first connecting area 232 of the first current collector 23 and the first connecting wall 2141 of the protrusion 214. This reduces the assembly difficulty of the cylindrical battery cell 20, optimizes the manufacturing process of the cylindrical battery cell 20, and helps to improve the production efficiency of the cylindrical battery cell 20.

[0367] According to some embodiments of this application, referring to Figures 5 and 6, along the axial direction of the cylindrical battery cell 20, the first connection area 232 is located on the side of the protrusion 214 facing the first wall 211, and the first connection area 232 is welded to the side of the protrusion 214 facing the first wall 211 to form a connection portion 24.

[0368] Along the axial direction of the cylindrical battery cell 20, the first connection area 232 is located on the side of the protrusion 214 facing the first wall 211. That is, the area where the first current collector 23 is welded to the first connection wall 2141 of the protrusion 214 is located on the side of the protrusion 214 facing the first wall 211 in the axial direction of the cylindrical battery cell 20, so that the electrode assembly 22 and the first connection area 232 are located on both sides of the protrusion 214 in the axial direction of the cylindrical battery cell 20.

[0369] The first connecting area 232 is welded to the side of the protrusion 214 facing the first wall 211 to form a connecting part 24. That is, the first connecting area 232 of the first current collector 23 is a structure welded to the side of the protrusion 214 facing the first wall 211. In the embodiment where the protrusion 214 includes two first connecting walls 2141, one of the two first connecting walls 2141 of the protrusion 214 facing the first wall 211 is welded to the first connecting area 232 of the first current collector 23 to form the connecting part 24.

[0370] In this embodiment, by setting the first connection area 232 of the first current collector 23 in the axial direction of the cylindrical battery cell 20 to be located on the side of the protrusion 214 facing the first wall 211 and welded to the side of the protrusion 214 facing the first wall 211, on the one hand, since the body area 231 of the first current collector 23 is located between the electrode assembly 22 and the protrusion 214, the first current collector 23 and the protrusion 214 can share a portion of the space in the axial direction of the cylindrical battery cell 20, which is beneficial to improving the internal space utilization of the cylindrical battery cell 20, thereby improving the cylindrical battery cell's performance. The energy density of the cell 20, on the other hand, makes the first connection area 232 of the first current collector 23 located on the side of the opening 2131 of the protrusion 214 facing the sidewall 213 in the axial direction of the cylindrical cell 20, and welded to the first connection wall 2141 of the protrusion 214. This allows the first connection wall 2141 of the protrusion 214 and the first connection area 232 of the first current collector 23 to be welded together from the opening 2131 of the sidewall 213, which is beneficial to optimizing the production process of the cylindrical cell 20 and reducing the assembly difficulty of the cylindrical cell 20.

[0371] Of course, the structure of the cylindrical battery cell 20 is not limited to this. In some embodiments, the cylindrical battery cell 20 can also have other structures. Referring to Figures 11 and 12, Figure 11 is a cross-sectional view of the cylindrical battery cell 20 provided in some embodiments of this application, and Figure 12 is a partial enlarged view of point B of the cylindrical battery cell 20 shown in Figure 11. Along the axial direction of the cylindrical battery cell 20, the first connecting area 232 is located on the side of the protrusion 214 facing away from the first wall 211, and the first connecting area 232 is welded to the side of the protrusion 214 facing away from the first wall 211 to form a connecting portion 24.

[0372] Along the axial direction of the cylindrical battery cell 20, the first connection area 232 is located on the side of the protrusion 214 away from the first wall 211. That is, the area where the first current collector 23 is welded to the first connection wall 2141 of the protrusion 214 is located on the side of the protrusion 214 away from the first wall 211 in the axial direction of the cylindrical battery cell 20, so that the electrode assembly 22 and the first connection area 232 are located on the same side of the protrusion 214 in the axial direction of the cylindrical battery cell 20.

[0373] The first connecting area 232 is welded to the side of the protrusion 214 away from the first wall 211 to form a connecting part 24. That is, the first connecting area 232 of the first current collector 23 is a structure welded to the side of the protrusion 214 away from the first wall 211. In the embodiment where the protrusion 214 includes two first connecting walls 2141, one of the two first connecting walls 2141 of the protrusion 214 away from the first wall 211 is welded to the first connecting area 232 of the first current collector 232 to form the connecting part 24.

[0374] In this embodiment, by setting the first connection area 232 of the first current collector 23 on the axial direction of the cylindrical battery cell 20 to be located on the side of the protrusion 214 away from the first wall 211 and welded to the side of the protrusion 214 away from the first wall 211, the first connection area 232 of the first current collector 23 and the electrode assembly 22 are both located on the side of the protrusion 214 away from the first wall 211. This helps to reduce the assembly difficulty of the first current collector 23 and the electrode assembly 22. In addition, the protrusion 214 can also play a certain role in limiting and positioning the first current collector 23.

[0375] According to some embodiments of this application, referring to Figures 6, 7, and 12, the sidewall 213 is bent at the end of the cylindrical battery cell 20 away from the second wall 212 to form a flange 2133, which encloses an opening 2131. Along the axial direction of the cylindrical battery cell 20, a portion of the first wall 211 is located between the flange 2133 and the protrusion 214, which are configured to cooperate in clamping the first wall 211.

[0376] The flange 2133 is a flange structure formed by bending the side wall 213 away from the second wall 212 in the axial direction of the cylindrical battery cell 20 towards the side closer to the receiving cavity. The flange 2133 surrounds and forms an opening 2131, that is, the flange 2133 is an annular structure, so that the opening 2131 is formed on the inner circumference of the flange 2133.

[0377] In this embodiment, the outer edge of the first wall 211 extends between the flange 2133 and the protrusion 214, so that the flange 2133 and the protrusion 214 can cooperate to clamp and assemble a portion of the first wall 211, thereby achieving the assembly connection between the first wall 211 and the side wall 213.

[0378] In this embodiment, a flange 2133 is formed by bending the side wall 213 away from the second wall 212 along the axial direction of the cylindrical battery cell 20, and a portion of the first wall 211 is positioned between the protrusion 214 and the flange 2133 in the axial direction of the cylindrical battery cell 20. This allows the protrusion 214 and the flange 2133 to also serve to assemble and fix the first wall 211, thereby achieving the assembly between the first wall 211 and the side wall 213. The cylindrical battery cell 20 with this structure can reduce the assembly difficulty between the first wall 211 and the side wall 213, thereby improving the production efficiency of the cylindrical battery cell 20.

[0379] According to some embodiments of this application, referring to Figures 6 and 12, the cylindrical battery cell 20 may further include a seal 27. The seal 27 is at least partially disposed radially between the sidewall 213 and the first wall 211 of the cylindrical battery cell 20, and the seal 27 is configured to seal the gap between the first wall 211 and the sidewall 213.

[0380] At least a portion of the seal 27 is disposed radially between the side wall 213 and the first wall 211 of the cylindrical battery cell 20, that is, at least a portion of the seal 27 is located between the outer peripheral surface of the first wall 211 and the inner peripheral surface of the side wall 213, so that the seal 27 can seal the gap between the outer peripheral surface of the first wall 211 and the inner peripheral surface of the side wall 213.

[0381] Optionally, the seal 27 is made of an insulating material, so that the seal 27 can also serve to insulate and isolate the first wall 211 and the side wall 213. For example, the material of the seal 27 can be rubber, silicone or plastic, etc.

[0382] In this embodiment, the cylindrical battery cell 20 is also provided with a sealing member 27. By disposing at least a portion of the sealing member 27 radially between the side wall 213 and the first wall 211 of the cylindrical battery cell 20, the sealing member 27 can seal the gap between the first wall 211 and the side wall 213, thereby reducing the risk of leakage during use of the cylindrical battery cell 20 and improving the stability and reliability of the cylindrical battery cell 20.

[0383] In some embodiments, referring to Figures 6 and 12, a portion of the seal 27 is disposed between the first wall 211 and the protrusion 214 along the axial direction of the cylindrical battery cell 20. That is, a portion of the seal 27 is located between the outer peripheral surface of the first wall 211 and the inner peripheral surface of the side wall 213, and the portion of the seal 27 extends between the first wall 211 and the protrusion 214, such that a portion of the seal 27 is located between the first wall 211 and the protrusion 214 in the axial direction of the cylindrical battery cell 20, so that the seal 27 can also separate the first wall 211 and the protrusion 214.

[0384] It should be noted that in the embodiment where the first connecting area 232 of the first current collector 23 is located on the side of the protrusion 214 facing the first wall 211 and is welded to the first connecting wall 2141 of the protrusion 214, as shown in FIG6, a portion of the seal 27 is located between the first connecting area 232 and the first wall 211, so that the seal 27 can also separate the first connecting area 232 and the first wall 211.

[0385] In this embodiment, by setting a portion of the seal 27 to extend between the first wall 211 and the protrusion 214, the seal 27 can also seal the gap between the first wall 211 and the protrusion 214, which is beneficial to further improve the sealing effect of the seal 27 on the gap between the first wall 211 and the side wall 213. Furthermore, the protrusion 214 and the first wall 211 can also play a certain clamping role on the seal 27, which is beneficial to improve the assembly stability of the seal 27.

[0386] In some embodiments, referring further to Figures 6 and 12, a portion of the seal 27 is disposed between the first wall 211 and the flange 2133 along the axial direction of the cylindrical battery cell 20. That is, a portion of the seal 27 is located between the outer peripheral surface of the first wall 211 and the inner peripheral surface of the side wall 213, and the portion of the seal 27 extends between the first wall 211 and the flange 2133, such that a portion of the seal 27 is located between the first wall 211 and the flange 2133 in the axial direction of the cylindrical battery cell 20, so that the seal 27 can also separate the first wall 211 and the flange 2133.

[0387] Optionally, the seal 27 is an annular structure surrounding the first wall 211. The seal 27 may include a first part, a second part, and a third part arranged and connected sequentially along the axial direction of the cylindrical battery cell 20. The first part is located between the protrusion 214 and the first wall 211 in the axial direction of the cylindrical battery cell 20. The second part is located between the outer peripheral surface of the first wall 211 and the inner peripheral surface of the side wall 213. The third part is located between the flange 2133 and the first wall 211 in the axial direction of the cylindrical battery cell 20.

[0388] In this embodiment, by setting a portion of the seal 27 to extend between the first wall 211 and the flange 2133, the seal 27 can also seal the gap between the first wall 211 and the flange 2133, which helps to further improve the sealing effect of the seal 27 on the gap between the first wall 211 and the side wall 213. Furthermore, the flange 2133 and the first wall 211 can also play a certain clamping role on the seal 27, which helps to improve the assembly stability of the seal 27.

[0389] According to some embodiments of this application, the material of the first current collector 23 includes copper.

[0390] According to some embodiments of this application, as shown in Figures 6 and 12, the first tab 222 is welded to the body region 231.

[0391] For example, the welding connection between the body region 231 of the first current collector 23 and the first electrode 222 can be of various types, such as laser welding or ultrasonic welding.

[0392] In this embodiment, by setting the first tab 222 and the body region 231 of the first current collector 23 as a welded connection, the reliability and robustness of the connection between the first tab 222 and the body region 231 of the first current collector 23 are improved, thereby enhancing the stability of the cylindrical battery cell 20 in use. Furthermore, the connection portion 24 formed by welding the first connecting region 232 of the first current collector 23 to the first connecting wall 2141 of the protrusion 214 is connected to the second connecting region 2141b. This allows the connecting portion 24 to be connected to the main body region 2141a via the second connecting region 2141b. This ensures that when the first tab 222 pulls on the first current collector 23 due to the shaking of the electrode assembly 22 during use of the cylindrical battery cell 20, the second connecting region 2141b can provide a buffering effect between the connecting portion 24 and the main body region 2141a, thus protecting the first current collector 23. The first connection area 232 of 3 has the ability to slightly float relative to the first connection wall 2141 of the protrusion 214, thereby alleviating the rigid tension between the first electrode 222 and the body area 231 of the first current collector 23. This helps to reduce the phenomenon of welding detachment between the first electrode 222 and the body area 231 of the first current collector 23. In turn, it can further reduce the risk of connection failure between the electrode assembly 22 and the side wall 213 of the casing 21 during the use of the cylindrical battery cell 20, so as to improve the stability and service life of the cylindrical battery cell 20.

[0393] According to some embodiments of this application, this application also provides a battery device 100, which includes a cylindrical battery cell 20 of any of the above embodiments.

[0394] As shown in Figure 2, the battery device 100 may also include a housing 10, in which cylindrical battery cells 20 are housed.

[0395] In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, the first housing body 11 and the second housing body 12 covering each other, the first housing body 11 and the second housing body 12 together defining an assembly space for accommodating the cylindrical battery cell 20.

[0396] Optionally, the second box body 12 can be a hollow structure with one end open, and the first box body 11 can be a plate-like structure. The first box body 11 covers the open side of the second box body 12 so that the first box body 11 and the second box body 12 together define the assembly space; the first box body 11 and the second box body 12 can also be hollow structures with one side open, and the open side of the first box body 11 covers the open side of the second box body 12.

[0397] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder or a cuboid. For example, in Figure 2, the box 10 is a cuboid structure.

[0398] Optionally, the cylindrical battery cell 20 disposed within the housing 10 can be one or more. For example, in Figure 2, the housing 10 of the battery device 100 contains multiple cylindrical battery cells 20. These cells can be connected in series, parallel, or a combination thereof. A combination thereof means that some of the cylindrical battery cells 20 are connected in series and others in parallel. The multiple cylindrical battery cells 20 can be directly connected in series, parallel, or a combination thereof, and then the entire assembly of the multiple cylindrical battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple cylindrical battery cells 20 first connected in series, parallel, or a combination thereof to form a battery module, and then these battery modules are connected in series, parallel, or a combination thereof to form a whole, which is then housed within the housing 10.

[0399] The battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar component that connects multiple cylindrical battery cells 20 to achieve electrical connection between the multiple cylindrical battery cells 20.

[0400] It should be noted that in some embodiments, the battery device 100 may not have a housing 10. The battery device 100 includes multiple cylindrical battery cells 20, and the battery device 100 composed of multiple cylindrical battery cells 20 can be directly mounted onto the electrical device to provide power to the electrical device through the multiple cylindrical battery cells 20. That is, the housing 10 can be part of the electrical device. Taking a vehicle 1000 as an example, the housing 10 can be part of the chassis structure of the vehicle 1000. For example, a portion of the housing 10 can be at least a part of the floor of the vehicle 1000, or a portion of the housing 10 can be at least a part of the crossbeams and longitudinal beams of the vehicle 1000.

[0401] According to some embodiments of this application, this application also provides an electrical device, which includes a cylindrical battery cell 20 of any of the above schemes, and the cylindrical battery cell 20 is used to provide electrical energy to the electrical device.

[0402] The electrical device can be any of the aforementioned devices or systems that utilize cylindrical battery cells 20.

[0403] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0404] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A cylindrical battery cell, comprising: The outer casing includes a first wall, a second wall, and a side wall. The first wall and the second wall are arranged opposite each other along the axial direction of the cylindrical battery cell. The side wall surrounds the first wall and the second wall, and the two ends of the side wall in the axial direction of the cylindrical battery cell are respectively connected to the first wall and the second wall. A protrusion is provided on the inner wall surface of the side wall, and the protrusion includes a first connecting wall. An electrode assembly, housed within the housing, the electrode assembly having a first tab; as well as A first current collector is disposed within the housing. The first electrode tab is electrically connected to the protrusion through the first current collector. The first current collector includes a body region and a first connecting region. The body region is connected to the first electrode tab. The first connecting region and the first connecting wall face each other along a first direction and are welded together to form a connecting part. The first connecting wall includes a main body region and a second connecting region arranged side by side along a second direction. A portion of the connecting part is embedded in the second connecting region, and the connecting part is connected to the main body region through the second connecting region. The first direction is parallel to the thickness direction of the first connecting wall, and the first direction is perpendicular to the second direction. Wherein, at least some of the grains in the second connection region are first grains, the ratio of the number of first grains to the total number of grains in the second connection region is greater than 50%, the second connection region intersects with a preset plane to form a first cross section, the preset plane is parallel to the first direction and the second direction, in the first cross section, the longest line among the multiple lines connecting any two points on the outer contour of the first grain is the first line, and the multiple lines connecting any two points on the outer contour of the first grain also include a second line, the second line is perpendicular to the first line and passes through the midpoint of the first line, and the ratio of the length of the first line to the length of the second line is in the range of 1 to 5.

2. The cylindrical battery cell of claim 1, wherein, The ratio of the length of the first connecting line to the length of the second connecting line is in the range of 1 to 3.

3. The cylindrical battery cell according to claim 1 or 2, wherein, The lengths of the first and second connecting lines are both 5 μm to 200 μm.

4. The cylindrical battery cell of any one of claims 1-3, wherein, At least some of the grains in the main body region are second grains, and the ratio of the number of second grains to the total number of grains in the main body region is greater than 50%. The main body region intersects with the preset plane to form a second cross section. In the second cross section, the longest line among the multiple lines connecting any two points on the outer contour of the second grain is the third line. The multiple lines connecting any two points on the outer contour of the second grain also include a fourth line. The fourth line is perpendicular to the third line and passes through the midpoint of the third line. The ratio of the length of the third line to the length of the fourth line is in the range of 5 to 100.

5. The cylindrical battery cell of claim 4, wherein, The length of the third connection is 150μm to 1000μm; The length of the fourth connection is 5μm to 120μm.

6. The cylindrical battery cell according to claim 4 or 5, wherein The angle between the extension direction of the third line and the second direction is 0° to 30°.

7. The cylindrical battery cell of any one of claims 4-6, wherein, The length of the third connection is greater than the length of the first connection.

8. The cylindrical battery cell of claim 7, wherein, The ratio of the length of the third connection to the length of the first connection is in the range of 1.5 to 150.

9. The cylindrical battery cell of claim 8, wherein, The ratio of the length of the third connection to the length of the first connection is in the range of 1.8 to 100.

10. The cylindrical battery cell of any one of claims 4-9, wherein, Along the second direction, the maximum size of the second grain is greater than the maximum size of the first grain.

11. The cylindrical battery cell of any one of claims 1-10, wherein, The Vickers hardness of the second connection region is less than that of the main body region.

12. The cylindrical battery cell of claim 11, wherein, The ratio of the Vickers hardness of the second connecting region to the Vickers hardness of the main body region is 0.3 to 0.

8.

13. The cylindrical battery cell of claim 12, wherein, The ratio of the Vickers hardness of the second connecting region to the Vickers hardness of the main body region is 0.5 to 0.

8.

14. The cylindrical battery cell of any one of claims 11-13, wherein, The Vickers hardness value of the second connecting region is 50 to 160.

15. The cylindrical battery cell of any one of claims 11-14, wherein, The Vickers hardness value of the main body region is 70 to 200.

16. The cylindrical battery cell of any one of claims 1-15, wherein, The second connection area includes two first sub-connection areas, which are located on both sides of the connection portion in the width direction of the connection portion.

17. The cylindrical battery cell of any one of claims 1-16, wherein, The first connection area and the second connection area are stacked along the first direction, and the connection portion connects the first connection area and the second connection area; Wherein, along the first direction, the second connection area has a first surface facing the first connection area, and within the first surface, the minimum distance between the orthographic projection of the portion of the connection embedded in the second connection area and the outer edge of the first surface is L1, satisfying 0.05mm≤L1≤2.5mm.

18. The cylindrical battery cell of any one of claims 1-17, wherein, The sidewall is formed on the side opposite to the electrode assembly and a groove is formed at the position corresponding to the protrusion. The protrusion includes two first connecting walls and a second connecting wall. The two first connecting walls are arranged opposite to each other along the first direction. The groove is formed between the two first connecting walls. The two ends of the second connecting wall in the first direction are respectively connected to the two first connecting walls. In this configuration, one of the two first connecting walls is welded to the first connecting area to form the connecting portion.

19. The cylindrical battery cell of claim 18, wherein, The wall thickness of the protruding portion is less than the wall thickness of the other portions of the protrusion.

20. The cylindrical battery cell of claim 18 or 19, wherein, The wall thickness of at least a portion of the protrusion is less than the wall thickness of the sidewall.

21. The cylindrical battery cell of any one of claims 1-20, wherein, The protrusion is a ring structure extending circumferentially along the sidewall, and the first connecting wall is a ring structure extending circumferentially along the sidewall.

22. The cylindrical battery cell of claim 21, wherein, The connecting portion extends circumferentially along the sidewall.

23. The cylindrical battery cell of claim 21 or 22, wherein, The first connecting wall has a plurality of second connecting areas, which are arranged at circumferential intervals along the side wall, and each second connecting area is connected to a connecting part.

24. The cylindrical battery cell according to any one of claims 1-23, wherein, The electrode assembly further includes a main body portion along the axial direction of the cylindrical battery cell. The main body portion is located on the side of the protrusion away from the first wall. The first tab is connected to the end of the main body portion facing the first wall, and the body region is located between the electrode assembly and the protrusion.

25. The cylindrical battery cell of claim 24, wherein, The first connection area is located on the side of the body area facing the first wall in the axial direction of the cylindrical battery cell; The first current collector further includes a transition region that connects the body region and the first connection region. The transition region is configured to deform when the body region and the first connection region move closer to or further away from each other along the axial direction of the cylindrical battery cell.

26. The cylindrical battery cell of claim 25, wherein, The transition area is bent to form multiple bent segments, which are connected sequentially. The bent segments at both ends of the multiple bent segments are respectively connected to the body area and the first connecting area.

27. The cylindrical battery cell of claim 25 or 26, wherein, The first wall is provided with a pressure relief component, which is configured to release the internal pressure of the cylindrical battery cell.

28. The cylindrical battery cell of claim 27, wherein, In a projection plane perpendicular to the axis of the cylindrical battery cell, the orthographic projection of the body region and the orthographic projection of the first connecting region form an exhaust gap in the radial direction of the cylindrical battery cell.

29. The cylindrical battery cell of claim 28, wherein, The pressure relief component is provided with a pressure relief groove, and at least a portion of the projection of the pressure relief groove on the axial direction of the cylindrical battery cell is located within the exhaust gap.

30. The cylindrical battery cell of any one of claims 27-29, wherein, In a projection plane perpendicular to the axis of the cylindrical battery cell, the orthographic projection of the first connection area extends circumferentially along the sidewall and is located on the periphery of the orthographic projection of the body area. The orthographic projections of the first connection area and the body area are arranged radially at intervals in the cylindrical battery cell. The diameter of the orthographic projection of the outer edge of the first connection area is d. The orthographic projection of the transition area extends radially along the cylindrical battery cell and has a length of L2, satisfying that 1 / 15 ≤ L2 / d ≤ 1 / 3.

31. The cylindrical battery cell of claim 30, wherein, 1 / 7≤L2 / d≤1 / 4.

32. The cylindrical battery cell of claim 30 or 31, wherein, 3mm≤L2≤15mm.

33. The cylindrical battery cell of any one of claims 30-32, wherein, The thickness of the transition region is T, and the width of the orthographic projection of the transition region in a projection plane perpendicular to the axial direction of the cylindrical battery cell is W, satisfying, 0.3mm 2 ≤ W x T ≤ 8mm 2 .

34. The cylindrical battery cell of claim 33, wherein, 2mm≤W≤10mm.

35. The cylindrical battery cell of claim 34, wherein, 3mm≤W≤5mm.

36. The cylindrical battery cell of any one of claims 33-35, wherein, 0.15mm≤T≤0.8mm.

37. The cylindrical battery cell of claim 36, wherein, 0.3mm≤T≤0.5mm.

38. The cylindrical battery cell of any one of claims 25-37, wherein, The thickness of the transition region is less than the thickness of the body region; and / or The thickness of the transition region is less than the thickness of the first connection region.

39. The cylindrical battery cell of any one of claims 24-38, wherein, The sidewall and the second wall are integrally formed, and the sidewall and the second wall enclose a receiving cavity, in which the electrode assembly is received; Along the axial direction of the cylindrical battery cell, the end of the sidewall away from the second wall forms an opening, and the first wall closes the opening.

40. The cylindrical battery cell of claim 39, wherein, Along the axial direction of the cylindrical battery cell, the first connection area is located on the side of the protrusion facing the first wall, and the first connection area is welded to the side of the protrusion facing the first wall to form the connection portion.

41. The cylindrical battery cell of claim 39, wherein, Along the axial direction of the cylindrical battery cell, the first connection area is located on the side of the protrusion away from the first wall, and the first connection area is welded to the side of the protrusion away from the first wall to form the connection portion.

42. The cylindrical battery cell of any one of claims 39-41, wherein, The sidewall is bent at the end away from the second wall in the axial direction of the cylindrical battery cell to form a flange, and the flange surrounds the opening. Wherein, along the axial direction of the cylindrical battery cell, a portion of the first wall is located between the flange and the protrusion, and the flange and the protrusion are configured to cooperate in clamping the first wall.

43. The cylindrical battery cell of claim 42, wherein, The cylindrical battery cell also includes: A seal, at least partially disposed radially between the sidewall and the first wall of the cylindrical battery cell, is configured to seal the gap between the first wall and the sidewall.

44. The cylindrical battery cell of any one of claims 1-43, wherein, The material of the first current collector includes copper.

45. The cylindrical battery cell of any one of claims 1-44, wherein, The first electrode tab is welded to the body region.

46. ​​A battery device comprising a cylindrical battery cell as claimed in any one of claims 1-45.

47. An electrical device comprising a cylindrical battery cell as claimed in any one of claims 1-45, the cylindrical battery cell being used to provide electrical energy.

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