Cylindrical battery cell, battery device, and electric device

Abstract

The present application relates to the field of batteries, and discloses a cylindrical battery cell (10), a battery device (100), and an electric device. The cylindrical battery cell (10) comprises a casing (2) and an electrode assembly (1). The casing (2) is provided with a pressure relief portion (22111). At least one electrode sheet (11) of the electrode assembly (1) comprises an electrode sheet body (111) and a tab (112). The tab (112) comprises a first tab winding portion (1121) and a second tab winding portion (1122), and the second tab winding portion (1122) extends beyond the first tab winding portion (1121) in a direction away from the electrode sheet body (111). The orthographic projection of the first tab winding portion (1121) is located within the orthographic projection of the pressure relief portion (22111). The pressure relief portion (22111) is at least partially opened during pressure relief to form an exhaust channel, and at least part of the electrode sheet (11) is discharged by means of the exhaust channel. In this way, directional pressure relief efficiency can be improved.

Description

Cylindrical battery cells, battery packs and electrical devices Technical Field

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

[0002] From a market perspective, the application of battery devices is becoming increasingly widespread. Battery devices are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. As the application areas of battery devices continue to expand, the market demand is also constantly increasing. Furthermore, the capacity of battery devices is becoming larger, and the performance requirements for battery devices are becoming increasingly stringent.

[0003] In related technologies, battery devices typically include one or more battery cells. During the use of a battery cell, external short circuits, overcharging, punctures, or flat-plate impacts can easily trigger thermal runaway.

[0004] For cylindrical battery cells, in some cases, the tabs of the cell generally have a significant binding effect, which strongly hinders the flow of high-temperature, high-pressure media. Therefore, during thermal runaway, the high-temperature, high-pressure media generated in a cylindrical battery cell spreads towards the pressure relief mechanism at a slower rate, resulting in lower efficiency for directional pressure relief through the mechanism.

[0005] The above statements are for the purpose of providing background information in relation to this application only and do not necessarily constitute prior art. Summary of the Invention

[0006] In view of the above problems, the purpose of this application is to provide a cylindrical battery cell, a battery device and an electrical device that can improve the technical problem of low directional pressure relief efficiency of cylindrical battery cells.

[0007] The technical solution adopted in the embodiments of this application is:

[0008] In a first aspect, embodiments of this application provide a cylindrical battery cell, comprising:

[0009] The outer casing has a pressure relief section at at least one end along the first direction;

[0010] An electrode assembly, at least partially disposed within a housing, is a wound structure and includes two electrodes with opposite polarities. At least one electrode includes an electrode body and an electrode tab arranged along a first direction. The electrode body is coated with an active material layer, and at least a portion of the electrode tab is not coated with an active material layer.

[0011] The electrode includes a first electrode winding portion and a second electrode winding portion disposed outside the first electrode winding portion. In a first direction, the second electrode winding portion extends beyond the first electrode winding portion in a direction away from the electrode body. On a projection plane perpendicular to the first direction, the orthographic projection of the first electrode winding portion is located within the orthographic projection of the pressure relief portion. The pressure relief portion is configured to at least partially open and form an exhaust channel when pressure is released, and at least a portion of the electrode is released to the outside of the housing through the exhaust channel.

[0012] The cylindrical battery cell provided in this application embodiment includes an electrode assembly with a first electrode winding portion and a second electrode winding portion located outside the first electrode winding portion. The second electrode winding portion extends beyond the first electrode winding portion along a first direction away from the electrode body, thereby reducing the binding effect of the first electrode winding portion and the binding effect between the first and second electrode winding portions. A pressure relief portion is provided at least at one end of the outer casing along the first direction, and the orthographic projection of the first electrode winding portion lies within the orthographic projection of the pressure relief portion on a projection plane perpendicular to the first direction. This reduces the self-binding effect of the electrode on at least a portion of the pressure relief portion (the first electrode winding portion), thereby also reducing the binding effect of the electrode on at least a portion of the pressure relief portion. The pressure relief section is configured to at least partially open and form an exhaust channel during pressure relief. At least a portion of the electrode sheet is discharged outside the casing through the exhaust channel. This allows the self-binding effect of the first tab winding portion and the binding effect between the first and second tab winding portions to be easily broken under air pressure during thermal runaway of the cylindrical battery cell. Consequently, at least a portion of the electrode sheet facing the pressure relief section can easily move towards the pressure relief section under air pressure and be discharged outside the casing through the exhaust channel formed by the opening of the pressure relief section. This reduces the obstruction effect of the tabs on the high-temperature, high-pressure medium. During this process, on the one hand, the high-temperature, high-pressure medium generated inside the cylindrical battery cell can be discharged outside the casing along with the electrode sheet; on the other hand, a large channel is formed in the area of ​​the electrode sheet facing the pressure relief section, and this channel gradually increases in size as the electrode sheet is discharged, facilitating the discharge of the high-temperature, high-pressure medium. This improves the discharge efficiency of the high-temperature, high-pressure medium, enabling the cylindrical battery cell to achieve efficient directional pressure relief, thereby contributing to improved reliability.

[0013] In some embodiments, the electrode assembly has a winding axis parallel to the first direction, and the second electrode winding portion has a bent section at one end in the first direction;

[0014] The bending section includes a first bending portion that is bent relative to the electrode body in a direction close to the winding axis, and / or the bending section includes a second bending portion that is bent relative to the electrode body in a direction away from the winding axis.

[0015] This configuration allows the end region of the tabs facing away from the electrode body along the first direction to be bent, thus gathering and assembling them to form a relatively dense stacked layer. This facilitates the welding of the second tab winding portion of the tabs to the current collector component discussed below. Furthermore, it provides a stronger binding effect on the electrode, resulting in higher charge-discharge performance for the electrode assembly.

[0016] In some embodiments, in the winding direction of the electrode assembly, the length of the second electrode lug winding portion is greater than the length of the first electrode lug winding portion.

[0017] This design allows the winding structure formed by the second electrode lug to have a large area for welding with the current collector, which can ensure the welding stability of the current collector and the electrode lug to a certain extent, and can also ensure the overall binding effect of the electrode sheet to a certain extent, so as to ensure the structural integrity and performance of the electrode assembly.

[0018] In some embodiments, the electrode includes a first electrode winding portion and a second electrode winding portion disposed outside the first electrode winding portion. The first electrode winding portion is formed at one end of the first electrode winding portion along a first direction, and the second electrode winding portion is formed at one end of the second electrode winding portion along the first direction. On a projection plane perpendicular to the first direction, the orthographic projection of the first electrode winding portion is located within the orthographic projection of the pressure relief portion. At least a portion of the first electrode winding portion is discharged outside the housing through the exhaust channel during pressure relief.

[0019] By adopting the above technical solution, during the thermal runaway of a cylindrical battery cell, the self-binding effect of the first electrode winding portion and the binding effect between the first and second electrode winding portions are easily broken under the action of air pressure. This allows at least a portion of the first electrode winding portion to loosen under air pressure and move towards the pressure relief section, where it is released to the outside of the casing through the exhaust channel formed by the opening of the pressure relief section. This improves the discharge efficiency of the high-temperature, high-pressure medium, enabling the cylindrical battery cell to achieve efficient directional pressure relief, thereby contributing to improved reliability.

[0020] In some embodiments, at least one electrode has a winding start end and a winding end end at its two ends along the winding direction of the electrode assembly, the winding end being formed in the second electrode winding portion and the winding start end being formed in the first electrode winding portion.

[0021] With this configuration, when the pressure inside the casing reaches a threshold, at least a portion of the electrode near the starting end of winding can be released outside the casing through the exhaust channel. This facilitates the loosening of at least a portion of the electrode under air pressure and release through the exhaust channel, which helps improve the directional pressure relief efficiency of the cylindrical battery cell.

[0022] In some embodiments, the electrode assembly has a central hole extending along a first direction. On a projection plane perpendicular to the first direction, the orthographic projection of the central hole is located within the orthographic projection of the pressure relief portion, and the first electrode winding portion is disposed around the outer periphery of the central hole.

[0023] The central hole facilitates the loosening of the electrode under air pressure and allows the electrode to be released outside the outer casing, thus facilitating exhaust and achieving a highly efficient directional pressure relief effect.

[0024] In some embodiments, the outer diameter of the electrode assembly is D1, the diameter of the central hole is D2, and D2 / D1 ∈ [5%, 25%].

[0025] This design allows the central hole to have a large diameter, which facilitates the discharge of the high-temperature and high-pressure medium inside the cylindrical battery cell to the pressure relief section through the central hole during thermal runaway, thereby achieving an efficient directional pressure relief effect.

[0026] In some embodiments, both electrodes include an electrode body and an electrode tab. The electrode tabs of the two electrodes are respectively disposed at both ends of the electrode assembly along the first direction. Each electrode tab includes a first electrode tab winding portion and a second electrode tab winding portion. On a projection plane perpendicular to the first direction, the orthographic projection of the first electrode tab winding portion of each electrode tab is located within the orthographic projection of the pressure relief portion.

[0027] This configuration allows at least a portion of the electrode assembly directly opposite the pressure relief section to be released outside the casing through the exhaust channel under air pressure, achieving a highly efficient directional pressure relief effect and thus contributing to the reliability of the cylindrical battery cell.

[0028] In some embodiments, the two electrodes include a positive electrode and a negative electrode, wherein the tabs of the positive electrode and / or the tabs of the negative electrode are not coated with an active material layer.

[0029] Thus, the tabs are not coated with an active material layer.

[0030] In some embodiments, the cylindrical battery cell further includes a current collector, at least a portion of which is disposed within the housing. The current collector is welded to the second tab winding portion but not to the first tab winding portion.

[0031] By welding the current collector to the second tab winding portion but not to the first tab winding portion, the self-binding effect of the first tab winding portion is weakened. This allows at least a portion of the electrode with the first tab winding portion to loosen under pressure during thermal runaway of the cylindrical battery cell, and to release pressure through the venting channel formed by the pressure relief portion, thereby improving the directional pressure relief effect of the cylindrical battery cell and contributing to its reliability.

[0032] In some embodiments, the cylindrical battery cell further includes an electrode terminal fixed to the housing and welded to the current collector to form a first weld portion, which is located on the outside of the first tab winding portion in the radial direction of the electrode assembly.

[0033] By positioning the first weld portion radially outside the first tab winding portion of the electrode assembly, the first weld portion is prevented from forming on the first tab winding portion. This allows the portion of the tab with the first weld portion to support the weld penetration depth of the current collector and electrode terminals, thus mitigating the problem of laser penetration and burn to the diaphragm during the welding process of the current collector and electrode terminals. This also improves the short-circuit problem of the electrode assembly and reduces the risk of short circuits.

[0034] In some embodiments, both electrodes include an electrode body and an electrode tab, wherein the electrode tab of one electrode is a first electrode tab and the electrode tab of the other electrode is a second electrode tab, and the first electrode tab and the second electrode tab are respectively disposed at both ends of the electrode assembly along the first direction; both the first electrode tab and the second electrode tab include a first electrode tab winding portion and a second electrode tab winding portion; on a projection plane perpendicular to the first direction, the orthographic projection of the first electrode tab winding portion of the first electrode tab and the orthographic projection of the first electrode tab winding portion of the second electrode tab are both located within the orthographic projection of the pressure relief portion;

[0035] In the first direction, both ends of the electrode assembly are provided with current collectors, and the current collectors at both ends of the electrode assembly are respectively a first current collector and a second current collector. The first current collector is welded to the second tab winding portion of the first tab, and the second current collector is welded to the second tab winding portion of the second tab.

[0036] This configuration allows at least a portion of the electrode assembly directly opposite the pressure relief section to be released outside the casing through the exhaust channel under air pressure, achieving a highly efficient directional pressure relief effect and thus contributing to the reliability of the cylindrical battery cell.

[0037] In some embodiments, the housing includes a first end wall, a second end wall, and a side wall. The first end wall and the second end wall are respectively disposed at both ends of the side wall along a first direction, and an electrode terminal is provided on the second end wall. The first electrode tab is electrically connected to the electrode terminal through a first current collector, and the second electrode tab is electrically connected to the side wall through a second current collector.

[0038] By adopting the above technical solution, at least one of the side wall, the first end wall and the second end wall can serve as one current transmission end of the cylindrical battery cell, and the electrode terminal serves as the other current transmission end of the cylindrical battery cell.

[0039] In some embodiments, the first end wall is welded to the second current collector, and the first end wall is electrically connected to the side wall.

[0040] This configuration allows the second current collector to be indirectly electrically connected to the sidewall via the first end wall.

[0041] In some embodiments, a protrusion is formed inwardly on the sidewall of the electrode assembly in the radial direction, the protrusion and the electrode assembly are distributed along a first direction, and a second current collector is welded to the side of the protrusion close to or away from the electrode assembly.

[0042] This configuration allows the second current collector to be directly electrically connected to the sidewall.

[0043] In some embodiments, a pressure relief portion is provided on the first end wall.

[0044] By adopting the above technical solution, the pressure relief section and the electrode terminals are respectively located at both ends of the outer casing along the first direction, which facilitates the layout of the pressure relief section and the electrode terminals and helps to improve the efficiency of assembling multiple cylindrical battery cells into a group.

[0045] In some embodiments, the first electrode is a positive electrode and the second electrode is a negative electrode.

[0046] By adopting the above technical solution, the electrode terminal is a positive electrode terminal, and at least one of the first end wall, the second end wall, and the side wall is a negative current transmission terminal of the cylindrical battery cell.

[0047] In some embodiments, the current collecting member is provided with an exhaust port extending in a first direction, and the exhaust port and the pressure relief portion are disposed opposite to each other in the first direction;

[0048] The flow collector is provided with multiple guide sections, which are spaced apart around the outer periphery of the exhaust port.

[0049] By adopting the above technical solution, during the thermal runaway of a cylindrical battery cell, when the pressure inside the casing reaches a threshold, the pressure relief section can open under the action of air pressure to form an exhaust channel. The guide section can also deform and open towards the pressure relief section under the action of air pressure, thereby gradually increasing the diameter of the exhaust channel. This facilitates the movement of the electrode plates towards the pressure relief section, allowing them to be released through the exhaust channel and exhaust hole to the outside of the casing. This design helps improve the directional pressure relief efficiency of the cylindrical battery cell.

[0050] In some embodiments, the guide extends to the exhaust port;

[0051] Alternatively, the guide portion and the wall of the exhaust hole are spaced apart, and the minimum distance between the guide portion and the wall of the exhaust hole is less than or equal to 10 mm.

[0052] This design allows the guide section to deform and open the portion of the flow collector near the exhaust port towards the pressure relief section during pressure relief, thereby increasing the size of the exhaust port and achieving a highly efficient directional pressure relief effect.

[0053] In some embodiments, on a projection plane perpendicular to the first direction, along the radial direction of the electrode assembly, the orthographic projection of the end of the guide portion away from the exhaust port is located outside the outer contour of the orthographic projection of the pressure relief portion or coincides with the outer contour of the orthographic projection of the pressure relief portion.

[0054] By adopting the above technical solution, the guide section can deform and open the current collector component towards the pressure relief section under the action of air pressure, and the diameter of the exhaust hole can be increased to a greater extent. In this way, during the thermal runaway of the cylindrical battery cell, when at least part of the electrode is released to the outside of the casing through the exhaust channel formed by the opening of the pressure relief section, the obstruction effect of the current collector component on the electrode can be reduced, which helps to improve the efficiency of the electrode releasing through the exhaust channel, thereby improving the directional pressure relief efficiency of the cylindrical battery cell.

[0055] In some embodiments, the guide portion includes a through hole extending through the current collecting member in a first direction;

[0056] And / or, the guide portion includes a second groove that does not penetrate the flow collector member in the first direction.

[0057] By adopting the above technical solution, the guide part can guide the part of the current collector near the exhaust hole to deform and open towards the pressure relief part during thermal runaway, thereby helping the cylinder to improve the directional pressure relief effect of the battery cell.

[0058] In some embodiments, the electrode assembly has a central hole extending along a first direction. On a projection plane perpendicular to the first direction, the orthographic projection of the central hole is located within the orthographic projection of the pressure relief portion. The central hole and the exhaust port are opposite to and connected along the first direction, and the first electrode lug is arranged around the outer periphery of the central hole.

[0059] With this configuration, when the pressure inside the casing reaches the threshold and the pressure relief section opens to form an exhaust channel, the central hole, exhaust through hole, and exhaust channel are connected sequentially along the first direction, which facilitates exhaust and helps improve the efficiency of directional pressure relief.

[0060] In some embodiments, on a projection plane perpendicular to the first direction, a portion of the orthographic projection of the second pole ear winding portion lies within the orthographic projection of the pressure relief portion.

[0061] By adopting the above technical solution, when the pressure inside the casing reaches a threshold, the first electrode winding portion and at least a portion of the electrode surrounding the first electrode winding portion can loosen under the action of air pressure and be released outside the casing through the exhaust channel. Furthermore, the high-temperature and high-pressure medium generated inside the cylindrical battery cell can also be released along with the electrode. This enables the cylindrical battery cell to achieve a highly efficient directional pressure relief effect.

[0062] In some embodiments, the second electrode ear winding portion includes a plurality of folded pieces distributed along the winding direction of the electrode assembly. Along the winding direction of the electrode assembly, a cutting groove is provided between any two adjacent pieces. On a projection plane perpendicular to the first direction, the orthographic projection of the bottom surface of the first groove of at least one cutting groove is located within the orthographic projection of the pressure relief portion.

[0063] In this way, during the thermal runaway of a cylindrical battery cell, the restraining effect of the second electrode winding portion on at least part of the pressure relief portion, and the restraining effect of the first electrode winding portion, are easily broken under the action of air pressure. This allows not only the first electrode winding portion to easily release pressure through the exhaust channel to the outside of the casing, but also at least the portion of the electrode surrounding the first electrode winding portion and directly opposite the pressure relief portion to easily release pressure through the exhaust channel to the outside of the casing. This helps the cylindrical battery cell achieve a highly efficient directional pressure relief effect, improving the problem of low directional pressure relief efficiency and thus contributing to improved reliability.

[0064] In some embodiments, the two electrodes include a positive electrode and a negative electrode, the tabs of the positive electrode and / or the tabs of the negative electrode are not coated with an active material layer, and in a first direction, an insulating layer is provided in the end region of the tab near the electrode body, and the cut-off piece is located on the side of the insulating layer away from the electrode body.

[0065] This allows the positive electrode to have an insulating layer, which effectively improves the short circuit problem between the positive and negative electrodes.

[0066] In some embodiments, the second electrode winding portion further includes a transition connection portion connected to the first electrode winding portion. The electrode body, the transition connection portion, and the slit are arranged sequentially along a first direction. The transition connection portion and any two slits adjacent to each other along the winding direction of the electrode assembly form a cutting groove, and the first bottom surface of the cutting groove is formed on one side edge of the transition connection portion used to connect the slit.

[0067] The transition connection between the electrode body and the cut-off piece allows the electrode body and the cut-off piece to be spaced apart along a first direction, as well as the electrode body and the cutting groove to be spaced apart along the first direction. This facilitates avoiding the electrode body during the cutting of the tabs to form the cutting groove and the cut-off piece, thus preventing the electrode body from being cut to some extent. Furthermore, it solves the problem of the electrode body being easily torn due to the first groove bottom surface being formed on one edge of the electrode body. On the other hand, the transition connection can block the cut-off piece, thus isolating it from the main body of the electrode assembly. This improves the problem of short circuits in the electrode assembly caused by the cut-off piece being bent and inserted into the main body, reducing the risk of short circuits.

[0068] In some embodiments, the dimension of one side edge of each segment used to connect the transition connection portion in the winding direction of the electrode assembly is H1, and the dimensions of the transition connection portion and the segment in the first direction are H2, where 0.01≤H2 / H1≤0.3.

[0069] This design allows the cut sheet to have a larger size in the winding direction, which facilitates the winding of the cut sheet and, to a certain extent, ensures the structural integrity of the electrode assembly and, to a certain extent, the charging and discharging performance of the cylindrical battery cell.

[0070] In some embodiments, the dimension of the transition connection in the first direction is H3, where 0.1mm≤H3≤2mm.

[0071] With this configuration, the transition connection portion has a suitable width in the first direction to block the cut-off piece, based on the fact that the tab can form a cut-off groove, thus improving the problem of the cut-off piece bending and being inserted into the main body.

[0072] In some embodiments, the cylindrical battery cell further includes a current collector and electrode terminals, at least a portion of the current collector is disposed within the housing, the electrode terminals are fixed to the housing, and the electrode terminals are welded to the current collector to form a first welded portion;

[0073] On the projection plane perpendicular to the first direction, the two ends of the orthographic projection of the first welded part have a first projection endpoint and a second projection endpoint, respectively. The first projection endpoint is closer to the first pole ear winding part than the second projection endpoint. The area between the first arc line that passes through the first projection endpoint and surrounds the first pole ear winding part and the second arc line that passes through the second projection endpoint and surrounds the first pole ear winding part is the first transverse area. At least some of the cut-off grooves form the first group of grooves. In the first group of grooves, the orthographic projection of the bottom surface of the first groove of all the cut-off grooves is located within the first transverse area.

[0074] Wherein, in the first group of slots, the number of turns of a single cut-off slot is ≤3; and / or, in the first group of slots, the number of cut-off slots that are radially opposite and interconnected along the electrode assembly is ≤3.

[0075] By adopting the above technical solution, based on the cutting groove provided in the part of the second electrode ear where the first weld portion is formed, the stacked layer formed by bending in the part of the second electrode ear where the first weld portion is formed will not be too thin due to the setting of the cutting groove. Thus, the part of the second electrode ear where the first weld portion is formed can bear the welding penetration of the current collector and the electrode terminal, which can improve the problem of laser penetrating the electrode ear and burning the diaphragm during the welding process of the current collector and the electrode terminal. This can improve the problem of short circuit of the electrode assembly caused by the welding of the current collector and the electrode terminal, and reduce the risk of short circuit.

[0076] In some embodiments, the cylindrical battery cell further includes a current collector, at least a portion of which is disposed within the housing; the current collector is welded to the slab and forms a second welded portion;

[0077] On the projection plane perpendicular to the first direction, the two ends of the orthographic projection of the second welded part have a third projection endpoint and a fourth projection endpoint, respectively. The third projection endpoint is closer to the first pole ear winding part than the fourth projection endpoint. The area between the third arc line that passes through the third projection endpoint and surrounds the first pole ear winding part and the fourth arc line that passes through the fourth projection endpoint and surrounds the first pole ear winding part is the second transverse region. At least some of the cut-off grooves form the second set of grooves. In the second set of grooves, the orthographic projection of the bottom surface of the first groove of all cut-off grooves is located within the second transverse region.

[0078] Wherein, in the second group of slots, the number of turns of a single cut-off slot is ≤3; and / or, in the second group of slots, the number of cut-off slots that are radially opposite and connected along the electrode assembly is ≤3.

[0079] By adopting the above technical solution, based on the cutting groove in the part of the second electrode ear where the second welding part is formed, the stacked layer formed by bending in the part of the second electrode ear where the second welding part is formed will not be too thin due to the setting of the cutting groove. Thus, the part of the second electrode ear where the second welding part is formed can bear the welding penetration of the current collector and the electrode ear. This can improve the problem of laser penetration of the electrode ear and burning of the diaphragm during the welding process of the current collector and the electrode ear. In this way, it can improve the problem of short circuit of the electrode assembly caused by welding of the current collector and the electrode ear and reduce the risk of short circuit.

[0080] In some embodiments, at least one electrode has a winding start end and a winding end end at both ends along the winding direction of the electrode assembly, and the second electrode ear winding portion near the winding end is provided with a notch groove, which penetrates the winding end along the winding direction of the electrode assembly and penetrates the end face of the electrode ear away from the electrode body.

[0081] The second electrode ear winding portion has a winding end section located at one end of the notch near the electrode body. In the first direction, the cut piece extends beyond the bottom surface of the second groove of the notch in a direction away from the electrode body. The bottom surface of the second groove is the end face of the winding end section away from the electrode body.

[0082] The above measures can improve the problem of laser penetration of the electrode tab and burning of the diaphragm during the welding process, thereby improving the short circuit problem of the electrode assembly and reducing the risk of short circuit.

[0083] In some embodiments, among the multiple segments of the second electrode winding portion, the segment furthest from the first electrode winding portion is wound at least one turn along the winding direction of the electrode assembly.

[0084] By winding the piece closest to the winding end at least once, the piece closest to the winding end can effectively wrap around the other pieces. This can improve the problem of internal short circuits caused by the pieces turning outward and inserting into the main body, thereby reducing the risk of short circuits.

[0085] In some embodiments, the second electrode ear winding portion is provided with a plurality of cutting grooves, and the cutting grooves and the cutting pieces are arranged alternately along the winding direction of the electrode assembly.

[0086] By forming multiple cut-off grooves on the second electrode lug winding section, a larger removal ratio can be achieved, allowing the portion of the electrode with cut-off grooves to release pressure through the venting channel formed by the pressure relief section during thermal runaway, thus achieving a highly efficient directional pressure relief effect. Furthermore, the deposited layer formed by bending the portion of the second electrode lug winding section with cut-off grooves is not too thin, effectively blocking the laser generated during welding, thereby achieving a protective effect for the diaphragm.

[0087] In some embodiments, in the first direction, the size of the truncated sheet along the winding direction of the electrode assembly tends to decrease in the direction away from the electrode body.

[0088] By setting the size of the cut sheet gradually decreasing in the direction away from the electrode body in the first direction along the winding direction, it helps to reduce the binding effect of the accumulated layer formed by bending in the end region of the cut sheet away from the electrode body. This helps the part of the electrode sheet with the cut-off groove to loosen during thermal runaway and release the pressure through the venting channel formed by the pressure relief section, which helps to improve the directional pressure relief efficiency.

[0089] In some embodiments, the electrode assembly has a winding axis parallel to a first direction, and at least one segment has a bent section at one end in the first direction.

[0090] The bending section includes a first bending portion disposed relative to the electrode body in a direction close to the winding axis, and / or, the bending section includes a second bending portion disposed relative to the electrode body in a direction away from the winding axis.

[0091] This configuration allows the end region of the second electrode loop winding portion away from the electrode body along the first direction to be bent, thereby gathering and assembling together to form a relatively dense stacked layer. This facilitates the welding of the second electrode loop winding portion to the current collector component described below. Furthermore, it provides a stronger binding effect on the electrode 11, resulting in higher charge / discharge performance for the electrode assembly 1.

[0092] In some embodiments, each segment has a bent section in a first direction.

[0093] This configuration allows each segment of the second electrode ear winding section to be bent, enabling the end region of the second electrode ear winding section away from the electrode body along the first direction to be bent, thereby gathering and assembling to form a relatively dense stacked layer.

[0094] In some embodiments, the first bending portion is bent radially along the electrode assembly; and / or, the second bending portion is bent radially along the electrode assembly.

[0095] By adopting the above technical solution, the bending section is bent radially, which enables the second electrode ear winding part to be bent well in order to form a stacked layer.

[0096] In some embodiments, the bending segment includes at least one first bending portion and at least one second bending portion, wherein the first bending portion and the second bending portion are alternately arranged along a first direction.

[0097] This configuration allows the end region of the second electrode ear winding portion that is away from the electrode body along the first direction to be bent, thereby gathering and assembling to form a relatively dense stacked layer.

[0098] In some embodiments, the housing further includes a first end wall opposite to the electrode assembly along a first direction, the first end wall having a first groove and a pressure relief portion located in the area enclosed by the first groove, the bottom of the first groove having a weak portion, the pressure relief portion being connected to the weak portion, at least a portion of the weak portion being configured to be disconnected during pressure relief to open the pressure relief portion.

[0099] By adopting the above technical solution, the pressure relief section can be opened to form an exhaust channel when the pressure value inside the cylindrical battery cell reaches the threshold, thereby facilitating the release of the electrode sheet to the outside of the casing through the exhaust channel formed by the pressure relief section under the action of air pressure.

[0100] In some embodiments, the housing further includes a first wall and a pressure relief mechanism. The first wall is disposed opposite to the electrode assembly along a first direction. The first wall is fixedly connected to the pressure relief mechanism. The pressure relief mechanism has a first groove and a pressure relief portion located in the area enclosed by the first groove. The bottom of the first groove has a weak portion. The pressure relief portion is connected to the weak portion. At least a portion of the weak portion is configured to be disconnected during pressure relief to open the pressure relief portion.

[0101] By adopting the above technical solution, the pressure relief section can be opened to form an exhaust channel when the pressure value inside the cylindrical battery cell reaches the threshold, thereby facilitating the release of the electrode sheet to the outside of the casing through the exhaust channel formed by the pressure relief section under the action of air pressure.

[0102] In some embodiments, the outer contour of the orthographic projection of the pressure relief portion is circular on a projection plane perpendicular to the first direction.

[0103] This design ensures that the exhaust channel formed by the pressure relief section is roughly circular, while the electrode assembly is roughly cylindrical. This facilitates the release of pressure through the exhaust channel when the electrode plate experiences thermal runaway, thereby helping to improve the directional pressure relief effect of the battery cell.

[0104] Secondly, embodiments of this application provide a battery device, including a cylindrical battery cell.

[0105] The battery device provided in this application adopts the cylindrical battery cells involved in the above embodiments, which enables the battery device to achieve a highly efficient directional pressure relief effect, thereby helping to improve the reliability and performance of the battery device.

[0106] Thirdly, embodiments of this application provide an electrical device, including a cylindrical battery cell or a battery device.

[0107] The electrical device provided in this application, by employing the cylindrical battery cells or battery devices involved in the above embodiments, helps to improve the reliability and performance of the electrical device.

[0108] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0109] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or exemplary technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0110] Figure 1 is a schematic diagram of a vehicle provided in some embodiments of this application;

[0111] Figure 2 is an exploded view of a battery device provided in some embodiments of this application;

[0112] Figure 3 is a schematic diagram of a cylindrical battery cell provided in some embodiments of this application;

[0113] Figure 4 is a cross-sectional view of Figure 3 along AA;

[0114] Figure 5 is a schematic diagram of the electrode assembly of the cylindrical battery cell shown in Figure 3;

[0115] Figure 6 is an enlarged view of point B in Figure 4;

[0116] Figure 7 is a projected schematic diagram of the pressure relief section and the tab of the cylindrical battery cell shown in Figure 3.

[0117] Figure 8 is a schematic diagram showing the unfolded electrode of the cylindrical battery cell provided in Figure 3;

[0118] Figure 9 is an enlarged view of point C in Figure 8;

[0119] Figure 10 is an enlarged view of point D in Figure 4;

[0120] Figure 11 is a partial unfolded schematic diagram of the positive electrode sheet of the cylindrical battery cell shown in Figure 3;

[0121] Figure 12 is a partial unfolded schematic diagram of the negative electrode sheet of the cylindrical battery cell shown in Figure 3;

[0122] Figure 13 is an enlarged view of point E in Figure 4;

[0123] Figure 14 is an enlarged view of point F in Figure 8;

[0124] Figure 15 is an enlarged view of point G in Figure 7;

[0125] Figure 16 is an enlarged view of point H in Figure 8;

[0126] Figure 17 is a schematic projection of the electrode assembly, current collector and electrode terminals of the cylindrical battery cell shown in Figure 3.

[0127] Figure 18 is a schematic projection of the electrode assembly and current collector of a cylindrical battery cell provided in some embodiments of this application;

[0128] Figure 19 is a schematic projection of the electrode assembly and current collector of a cylindrical battery cell provided in some other embodiments of this application;

[0129] Figure 20 is a partial cross-sectional view of a cylindrical battery cell provided in some other embodiments of this application;

[0130] Figure 21 is a schematic projection of the current collector and pressure relief section of the cylindrical battery cell shown in Figure 3.

[0131] In the figures, the following labels are used: 1000-Vehicle; 100-Battery unit; 200-Controller; 300-Motor; 10-Cylindrical battery cell; 1-Electrode assembly; 101-Center hole; 102-Cut-off groove; 103-Bottom of the first groove; 104-Winding start end; 105-Winding end; 106-Notch groove; 107-Bottom of the second groove; 11-Electrode sheet; 11a-Positive electrode sheet; 11b-Negative electrode sheet; 111-Electrode sheet body; 111a-First electrode sheet body; 111b-Second electrode sheet body; 1111-Active material layer; 1112-First body winding section; 1113-Second body winding section; 112-Taper; 112a-Positive electrode tab; 112 b - Negative electrode tab; 1121 - First electrode tab winding section; 1122 - Second electrode tab winding section; 11221 - Cut piece; 112211 - Bending section; 1122111 - First bending section; 1122112 - Second bending section; 11222 - Transition connection section; 112221 - Middle winding section; 112222 - End winding section; 113 - Insulating layer; 114 - First electrode plate winding section; 115 - Second electrode plate winding section; 12 - Diaphragm; 2 - Outer shell; 201 - First groove ; 202-Groove; 21-Housing; 211-Second end wall; 212-Side wall; 2121-Protrusion; 22-End cap; 221-First end wall; 2211-Pressure relief mechanism; 22111-Pressure relief part; 22112-Weak part; 2212-First wall; 3-Current collector; 3a-First current collector; 3b-Second current collector; 301-Exhaust hole; 31-Current collector body; 32-Guide part; 321-First edge; 4-First welding part; 5-Electrode terminal; 6- Second welding section; 20-box body; 210-first part; 220-second part; P-main body; M1-first projection endpoint; M2-second projection endpoint; M3-first arc; M4-second arc; M5-first transverse region; N1-third projection endpoint; N2-fourth projection endpoint; N3-third arc; N4-fourth arc; N5-second transverse region; L-winding axis; Z-first direction; Y-radial; E-circumferential; W-winding direction; X-length direction. Detailed Implementation

[0132] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0133] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0134] Unless otherwise specified, all technical features and optional technical features of the embodiments of this application can be combined with each other to form new technical solutions.

[0135] In the description of the embodiments of this application, it should be understood that the terms "length", "width", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0136] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0137] In the description of the embodiments of this application, "multiple" means two or more, and unless otherwise explicitly specified, "two or more" includes two. Correspondingly, "multiple groups" means two or more groups, including two groups.

[0138] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0139] In the description of 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 three possibilities: A exists, A and B exist simultaneously, and B exists. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0140] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0141] From a market perspective, the application of battery devices is becoming increasingly widespread. Battery devices are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. As the application areas of battery devices continue to expand, the market demand is also constantly increasing. Furthermore, the capacity of battery devices is becoming larger, and the performance requirements for battery devices are becoming increasingly stringent.

[0142] In related technologies, battery devices typically include one or more battery cells. During the use of a battery cell, external short circuits, overcharging, punctures, or flat-plate impacts can easily trigger thermal runaway.

[0143] A battery cell is the smallest unit used to store and output electrical energy. Battery cells can be cylindrical, flat, cuboid, or other shapes; those roughly cylindrical are called cylindrical battery cells.

[0144] A cylindrical battery cell mainly consists of a cylindrical outer casing and electrode components located inside the casing. The outer casing may be equipped with a pressure relief mechanism. During the thermal runaway process of a cylindrical battery cell, when the internal pressure reaches a threshold, the pressure relief mechanism opens to form an exhaust channel. The high-temperature and high-pressure flue gas, high-temperature and high-pressure particulate matter, and other high-temperature and high-pressure media inside the cylindrical battery cell will mainly spread towards the pressure relief mechanism on the outer casing and be released outside the casing through the exhaust channel, achieving a directional pressure relief effect.

[0145] The electrode assembly mainly consists of two electrodes with opposite polarities, designated as a positive and a negative electrode. The positive and negative electrodes are alternately stacked and wound to form a wound structure. Each electrode typically includes an electrode body and tabs, which are full tabs. The tab layers have significant mutual binding force, meaning the tabs themselves provide strong resistance to high-temperature, high-pressure media.

[0146] For example, after the electrode sheets are wound to form an electrode assembly, the tabs can be bent to gather and aggregate the ends of the tabs away from the electrode body, forming a relatively dense stacked layer. On the one hand, this reduces the gaps between the tab layers, facilitating welding of the tabs to the current collector. On the other hand, it allows the tabs to provide strong binding force to the entire electrode sheet, ensuring the structural integrity of the electrode assembly to a certain extent and improving its charge-discharge performance. Thus, the tab layers have a significant mutual binding force, meaning the tabs themselves have a strong binding effect, which strongly hinders the flow of high-temperature, high-pressure media. Consequently, the discharge of high-temperature, high-pressure media generated during thermal runaway in a cylindrical battery cell is restricted, resulting in a lower discharge rate. This makes it difficult for the high-temperature, high-pressure media to spread to the pressure relief mechanism and be released outside the casing in a timely manner. Instead, it accumulates inside the cylindrical battery cell, leading to lower efficiency and poorer effect of directional pressure relief through the pressure relief mechanism. As thermal runaway continues in a cylindrical battery cell, the internal pressure increases, posing a significant risk of explosion and thus reducing the cell's reliability.

[0147] Based on the above considerations, embodiments of this application provide a cylindrical battery cell, a battery device, and an electrical device. The electrode assembly includes a first electrode winding portion and a second electrode winding portion located outside the first electrode winding portion. The second electrode winding portion extends beyond the first electrode winding portion along a first direction away from the electrode body, thereby reducing the binding effect of the first electrode winding portion and the binding effect between the first and second electrode winding portions. A pressure relief portion is provided at least at one end of the outer casing along the first direction, and the orthographic projection of the first electrode winding portion lies within the orthographic projection of the pressure relief portion on a projection plane perpendicular to the first direction. This reduces the self-binding effect of the electrode on at least a portion of the pressure relief portion (the first electrode winding portion), thereby also reducing the binding effect of the electrode on at least a portion of the pressure relief portion. The pressure relief section is configured to at least partially open and form an exhaust channel during pressure relief. At least a portion of the electrode sheet is discharged outside the casing through the exhaust channel. This allows the self-binding effect of the first tab winding portion and the binding effect between the first and second tab winding portions to be easily broken under air pressure during thermal runaway of the cylindrical battery cell. This enables at least a portion of the electrode sheet facing the pressure relief section to move towards the pressure relief section under air pressure and be discharged outside the casing through the exhaust channel formed by the opening of the pressure relief section. This reduces the obstruction effect of the tabs on the high-temperature, high-pressure medium. During this process, on the one hand, the high-temperature, high-pressure medium generated inside the cylindrical battery cell can be discharged outside the casing along with the electrode sheet. On the other hand, a large channel is formed in the area of ​​the electrode sheet facing the pressure relief section, and this channel gradually increases in size as the electrode sheet is discharged, facilitating the discharge of the high-temperature, high-pressure medium. This improves the discharge efficiency of the high-temperature, high-pressure medium, enabling the cylindrical battery cell to achieve efficient directional pressure relief, thereby contributing to improved reliability.

[0148] The cylindrical battery cell involved in this application refers to the smallest unit used for storing and outputting electrical energy. The cylindrical battery cell can be a secondary battery or a primary battery. A secondary battery refers to a cylindrical battery cell that can be recharged after discharge to activate the active materials and continue to be used. The cylindrical 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. The cylindrical battery cell can be cylindrical, flat, cuboid, or other shapes.

[0149] The battery device involved in this application embodiment can be a single physical module comprising one or more cylindrical battery cells, used to provide voltage and capacity. When there are multiple cylindrical battery cells, the multiple cylindrical battery cells are connected in series, in parallel, or in a mixed connection via a busbar. A mixed connection refers to multiple cylindrical battery cells being connected in both series and parallel connections.

[0150] In some embodiments, the battery device can be a battery module. When there are multiple cylindrical battery cells, the multiple cylindrical battery cells are arranged and fixed to form a battery module. As an example, multiple cylindrical battery cells can be fixed to form a battery module using cable ties or the like. As an example, multiple cylindrical battery cells can be fixed to form a battery module using end plates, side plates, or the like.

[0151] In some embodiments, the battery device can be a battery pack, which may include a housing and cylindrical battery cells. As an example, the cylindrical battery cells may be directly housed within the housing. As another example, multiple cylindrical battery cells may first be formed into one or more battery modules and then housed within the housing.

[0152] The cylindrical battery cells and battery devices involved in the embodiments of this application can be used in energy storage devices that use cylindrical battery cells or battery devices as energy storage elements.

[0153] The energy storage device involved in this application embodiment can be an energy storage container or an energy storage cabinet. The energy storage device can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems, etc. The energy storage device can store electrical energy as needed and output electrical energy when appropriate. For example, the energy storage device can store electrical energy during off-peak hours and provide power to relevant users or electrical devices during peak hours. The energy storage device can include one or more battery clusters, and each battery cluster includes multiple battery devices. Multiple battery devices in a battery cluster can be connected in series through a busbar to increase the voltage of the energy storage device. When the energy storage device includes multiple battery clusters, the multiple battery clusters can be connected in parallel to increase the capacity of the energy storage device.

[0154] In some embodiments, the energy storage device may further include a cabinet in which the battery clusters are housed.

[0155] The cylindrical battery cell and battery device provided in this application embodiment can also be used in electrical devices that use cylindrical battery cells or battery devices as power sources.

[0156] Electrical devices can include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, vehicles, 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. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft. Based on the power source, vehicles can be gasoline-powered vehicles, natural gas-powered vehicles, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles. Based on the drive method, vehicles can be front-wheel drive vehicles, rear-wheel drive vehicles, or four-wheel drive vehicles.

[0157] For ease of description, this application uses a vehicle as an example to illustrate the embodiments of the electrical device.

[0158] In some embodiments, please refer to FIG1, which is a schematic diagram of a vehicle 1000 provided in some embodiments of this application. A battery device 100 is disposed inside the vehicle 1000, and the battery device 100 may 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, the battery device 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0159] In some embodiments, the battery device 100 can not only serve as the operating 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.

[0160] In some embodiments, please refer to FIG2, which is an exploded view of a battery device 100 provided in some embodiments of this application. The battery device 100 may include a housing 20 and cylindrical battery cells 10. The housing 20 is a structure with an internal space for accommodating the cylindrical battery cells 10.

[0161] The housing 20 can adopt various structures. In some embodiments, the housing 20 may include a first portion 210 and a second portion 220, which overlap each other and together define the internal space of the housing 20, which is a closed space. Here, "closed" means covered or closed, and can be sealed or unsealed. That is, the housing 20 can be a sealed structure or an unsealed structure.

[0162] In this configuration, both the first part 210 and the second part 220 can be hollow structures with an opening at one end. The open side of the first part 210 covers the open side of the second part 220, so that the first part 210 and the second part 220 together define the internal space of the box 20. Alternatively, referring to Figure 2, the first part 210 can be a hollow structure with an opening at one end, and the second part 220 is a plate-like structure. The second part 220 covers the open side of the first part 210, so that the first part 210 and the second part 220 together define the internal space of the box 20.

[0163] The box 20, which is composed of the first part 210 and the second part 220, can be of various shapes, such as cylinder, cuboid, etc.

[0164] In some embodiments, multiple cylindrical battery cells 10 can be connected in series, parallel, or mixed to form a whole, and then the whole formed by the multiple cylindrical battery cells 10 is directly housed in the internal space of the housing 20. In other embodiments, multiple cylindrical battery cells 10 can also be connected in series, parallel, or mixed to form a battery module, and the battery module is housed in the internal space of the housing 20. In still other embodiments, multiple cylindrical battery cells 10 can also be connected in series, parallel, or mixed to form multiple battery modules, and the multiple battery modules can then be connected in series, parallel, or mixed to form a whole, and housed in the internal space of the housing 20.

[0165] In some embodiments, referring to Figures 1 and 2, the housing 20 of the battery device 100 can be part of the chassis structure of the vehicle 1000. For example, a portion of the housing 20 can be at least a portion of the floor of the vehicle 1000, or a portion of the housing 20 can be at least a portion of the crossbeams and longitudinal beams of the vehicle 1000.

[0166] In some embodiments, please refer to Figures 3 to 5 together with other accompanying drawings. Figure 3 is a perspective structural diagram of a cylindrical battery cell 10 provided in some embodiments of this application; Figure 4 is a cross-sectional view along line AA of Figure 3; and Figure 5 is a schematic diagram of the electrode assembly 1 of the cylindrical battery cell 10 provided in Figure 3. The cylindrical battery cell 10 provided in the embodiments of this application may include the electrode assembly 1 and the housing 2.

[0167] Electrode assembly 1 is the component in the cylindrical battery cell 10 where the electrochemical reaction takes place. Electrode assembly 1 is mainly formed by alternating layers and winding of positive electrode 11a and negative electrode 11b, with a separator 12 between the positive electrode 11a and the negative electrode 11b. The separator 12 isolates the positive electrode 11a and the negative electrode 11b, thus insulating them.

[0168] In the cylindrical battery cell 10, the number of electrode components 1 can be one or more.

[0169] Among them, electrode assembly 1 can also be referred to as bare cell, winding body, etc.

[0170] In some embodiments, the cylindrical battery cell 10 may further include an electrolyte, which serves to conduct ions between the positive electrode 11a and the negative electrode 11b. The electrolyte involved in these embodiments may be liquid, gel-like, or solid.

[0171] The housing 2 is used to define the internal environment of the cylindrical battery cell 10 and to house the electrode assembly 1 and the electrolyte.

[0172] In some embodiments, please refer to Figures 3 to 5 together with other figures. The housing 2 may include a housing 21 and an end cap 22, which are components for jointly defining the internal environment of the cylindrical battery cell 10. The internal environment defined by the housing 21 and the end cap 22 is used to accommodate the electrode assembly 1 and the electrolyte.

[0173] The outer shell 2 is cylindrical. Specifically, the shell 21 is cylindrical.

[0174] As shown in Figure 5, the housing 21 and the end cap 22 can be independent components. Specifically, the housing 21 has an opening, and the end cap 22 is placed over the opening of the housing 21 to jointly define the internal environment of the cylindrical battery cell 10 and isolate the internal environment of the cylindrical battery cell 10 from the external environment. Alternatively, the housing 21 and the end cap 22 can be an integrated structure. Specifically, the end cap 22 and the housing 21 can form a common connection surface before the electrode assembly 1 is inserted into the housing. After the electrode assembly 1 is inserted into the housing, when it is necessary to encapsulate the electrode assembly 1, the end cap 22 closes the housing 21.

[0175] The outer casing 2 can be either a sealed or unsealed structure. As an example, if the outer casing 2 is a sealed structure, it can protect the electrode assembly 1 and, to some extent, prevent leakage such as electrolyte leakage. As another example, if the outer casing 2 is an unsealed structure, it can still protect the electrode assembly 1, and a sealing bag may be included between the outer casing 2 and the electrode assembly 1 to encapsulate the electrode assembly 1 and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating structure, Mylar membrane, etc.

[0176] As shown in Figures 3 to 5, there can be one end cap 22, which is located at one end of the housing 21. Alternatively, there can be two end caps 22, which are located at opposite ends of the housing 21.

[0177] The shell 21 and end cap 22 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0178] Please refer to Figures 3 through 9, and in conjunction with other accompanying figures. Figure 6 is an enlarged view of section B in Figure 4. In Figure 6, the first tab winding portion 1121 and the second tab winding portion 1122 are separated by dashed lines. Figure 7 is a projection schematic diagram of the pressure relief portion 22111 and the tab 112 of the cylindrical battery cell 10 provided in Figure 3. Specifically, it is a schematic diagram of the orthographic projection of the pressure relief portion 22111 and the tab 112 on a projection plane perpendicular to the first direction Z. On the projection plane perpendicular to the first direction Z, the orthographic projection of the tab 112 includes the orthographic projection of the first tab winding portion 1121 and the orthographic projection of the root position of the second tab winding portion 1122. The orthographic projection of the root position of the second tab winding portion 1122 can be the orthographic projection of the transition connection portion 11222 of the second tab winding portion 1122. In Figure 7, the outer contour lines of the pressure relief section 22111, the cut-off groove 102, the notch groove 106, and the first electrode winding section 1121 are all dashed lines. Figure 8 is a schematic diagram of the unfolded electrode 11 of the cylindrical battery cell 10 provided in Figure 3. In Figure 8, the first electrode winding section 114 and the second electrode winding section 115 are divided by dashed lines. Figure 9 is an enlarged view of point C in Figure 8. In Figure 9, the cut-off piece 11221 and the transition connection section 11222 are divided by dashed lines. The cylindrical battery cell 10 provided in this embodiment includes a housing 2 and an electrode assembly 1. The housing 2 has a pressure relief section 22111 at at least one end along the first direction Z. At least a portion of the electrode assembly 1 is disposed inside the housing 2. Electrode assembly 1 has a wound structure and includes two electrodes 11 with opposite polarities. At least one electrode 11 includes an electrode body 111 and an electrode tab 112 arranged along a first direction Z. The electrode body 111 is coated with an active material layer 1111, and at least a portion of the electrode tab 112 is not coated with the active material layer 1111. The electrode tab 112 includes a first electrode tab wound portion 1121 and a second electrode tab wound portion 1122, with the second electrode tab wound portion 1122 located outside the first electrode tab wound portion 1121. In the first direction Z, the second electrode tab wound portion 1122 extends beyond the first electrode tab wound portion 1121 in a direction away from the electrode body 111. On a projection plane perpendicular to the first direction Z, the orthographic projection of the first electrode tab wound portion 1121 is within the orthographic projection of the pressure relief portion 22111. The pressure relief section 22111 is configured to at least partially open and form an exhaust passage during pressure relief, through which at least a portion of the electrode 11 is discharged to the outside of the housing 2.

[0179] The pressure relief part 22111 refers to a component on the housing 2 that can be at least partially opened during pressure relief. It is understood that the housing 2 includes a pressure relief mechanism 2211, and the pressure relief mechanism 2211 includes the pressure relief part 22111, that is, the pressure relief part 22111 is at least a part of the pressure relief mechanism 2211.

[0180] The pressure relief mechanism 2211 is a mechanism that releases the internal pressure of the cylindrical battery cell 10 when the pressure value inside the cylindrical battery cell 10 reaches a threshold. For example, when the cylindrical battery cell 10 is operating normally, the gas pressure inside the cylindrical battery cell 10 is less than the opening pressure value of the pressure relief mechanism 2211, and the pressure relief mechanism 2211 is in the closed state, and the gas inside the cylindrical battery cell 10 is not connected to the external gas. When the cylindrical battery cell 10 experiences thermal runaway under the influence of internal and external factors such as overcharging, over-discharging, overheating, and mechanical impact, a large amount of high-temperature and high-pressure medium is generated inside the cylindrical battery cell 10, causing the internal pressure of the cylindrical battery cell 10 to exceed the opening pressure value of the pressure relief mechanism 2211. The pressure relief mechanism 2211 changes from the closed state to the open state, and the high-temperature and high-pressure medium inside the cylindrical battery cell 10 can be discharged to the outside of the cylindrical battery cell 10 through the pressure relief mechanism 2211.

[0181] When the cylindrical battery cell 10 experiences thermal runaway, at least a portion of the pressure relief section 22111 opens to achieve directional pressure relief.

[0182] For ease of description, the outer casing 2 is defined to have a first end wall 221 at at least one end along the first direction Z, and the first end wall 221 is provided with a pressure relief mechanism 2211. Specifically, as shown in Figures 4 and 6, the first end wall 221 includes a first wall 2212 and the aforementioned pressure relief mechanism 2211, with the pressure relief mechanism 2211 connected to the first wall 2212. The first end wall 221 is the end structure of the outer casing 2 at at least one end along the first direction Z. The first wall 2212 is the solid wall of the outer casing 2 at at least one end along the first direction Z, and is the portion of the first end wall 221 excluding the pressure relief mechanism 2211. The first wall 2212 and the electrode assembly 1 are disposed opposite each other along the first direction Z. The pressure relief mechanism 2211 can be integrally formed on the first wall 2212, as shown in Figures 4 and 6; or, the pressure relief mechanism 2211 can be separately disposed on the first wall 2212.

[0183] The outer casing 2 may be provided with a pressure relief mechanism 2211 on the housing 21. It is understood that the first end wall 221 is a part of the housing 21. The end cover 22 of the outer casing 2 may also be provided with a pressure relief mechanism 2211. It is understood that, as shown in Figures 4 and 6, the first end wall 221 is at least a part of the end cover 22.

[0184] The outer casing 2 has a first end wall 221 at one end along the first direction Z, that is, a pressure relief mechanism 2211 at one end along the first direction Z, as shown in Figures 4 and 6. Alternatively, the outer casing 2 has a first end wall 221 at both ends along the first direction Z, that is, a pressure relief mechanism 2211 at both ends along the first direction Z.

[0185] As shown in Figure 5, the electrode assembly 1 includes two electrodes 11 with opposite polarities. Specifically, the electrode assembly 1 includes two electrodes 11 with opposite polarities, and these two electrodes 11 can be a positive electrode 11a and a negative electrode 11b, respectively. The positive electrode 11a can include an electrode body 111 and a tab 112 arranged along the first direction Z. The electrode body 111 of the positive electrode 11a is the first electrode body 111a, and the tab 112 of the positive electrode 11a is the positive electrode tab 112a. Similarly, the negative electrode 11b can also include an electrode body 111 and a tab 112 arranged along the first direction Z. The electrode body 111 of the negative electrode 11b is the second electrode body 111b, and the tab 112 of the negative electrode 11b is the negative electrode tab 112b. Understandably, the aforementioned electrode body 111 can be the electrode body 111 of the positive electrode 11a, which is the first electrode body 111a; or it can be the electrode body 111 of the negative electrode 11b, which is the second electrode body 111b. The aforementioned tab 112 can be the tab 112 of the positive electrode 11a, which is the positive tab 112a; or it can be the tab 112 of the negative electrode 11b, which is the negative tab 112b.

[0186] When both the positive electrode 11a and the negative electrode 11b include an electrode body 111 and an electrode tab 112, the electrode body 111 of the positive electrode 11a, the electrode body 111 of the negative electrode 11b, and the diaphragm 12 can constitute the main body P of the electrode assembly 1. That is, the main body P is mainly composed of the first electrode body 111a, the second electrode body 111b, and the diaphragm 12. The diaphragm 12 is mainly disposed between the electrode body 111 of the positive electrode 11a and the electrode body 111 of the negative electrode 11b. The positive electrode tab 112a and the negative electrode tab 112b can be located together at one end of the main body P along the first direction Z, that is, the electrode assembly 1 has a tab 112 at one end along the first direction Z; or, as shown in Figures 4 and 5, the positive electrode tab 112a and the negative electrode tab 112b are respectively provided at both ends of the main body P along the first direction Z, that is, the electrode assembly 1 has tabs 112 at both ends along the first direction Z.

[0187] The electrode body 111 and the electrode tab 112 can be integrally formed, as shown in Figure 5. Alternatively, the electrode body 111 and the electrode tab 112 can be connected separately.

[0188] Among them, the electrode 112 may be, but is not limited to, a full electrode 112.

[0189] The electrode assembly 1 has a wound structure, meaning that the electrode sheet 11 is wound to form a wound structure. Specifically, both the electrode body 111 and the tab 112 of the electrode sheet 11 are wound, so that both the electrode body 111 and the tab 112 are wound structures. As an example, as shown in Figures 3 and 5, the electrode sheet 11 is wound to form a wound structure, so that the electrode assembly 1 can be approximately cylindrical. Correspondingly, the outer casing 2 is approximately cylindrical, so that the cylindrical battery cell 10 is cylindrical as a whole.

[0190] It should be further noted that the cylindrical battery cell 10 has a winding axis L, which extends along the first direction Z. Furthermore, the electrode 11 is wound around the winding axis L to form a wound structure. Specifically, both the electrode body 111 and the tab 112 are arranged around the winding axis L.

[0191] The electrode body 111 may be completely coated with the active material layer 1111; or, a portion of the electrode body 111 may be coated with the active material layer 1111, while the other portion may not be coated with the active material layer 1111. The tab 112 may be completely uncoated with the active material layer 1111; or, a portion of the tab 112 may be coated with the active material layer 1111, while the other portion may not be coated with the active material layer 1111. The active material layer 1111 refers to a structural layer composed of active materials.

[0192] For ease of description, the winding direction W of electrode assembly 1 can be simply referred to as the winding direction W, and the radial direction Y of electrode assembly 1 can be simply referred to as the radial direction Y, specifically the radial direction of electrode assembly 1. The winding direction W of electrode assembly 1 refers to the direction in which the electrode sheet 11 is wound to form electrode assembly 1, that is, the winding direction W of the tab 112 and the winding direction W of the electrode body 111. The first direction Z is approximately the axial direction of the cylindrical battery cell 10, or it can be the width direction of the electrode sheet 11. The first direction Z is approximately perpendicular to the winding direction W of electrode assembly 1, and the first direction Z is approximately perpendicular to the radial direction Y of electrode assembly 1. The first direction Z is approximately perpendicular to the length direction X of electrode sheet 11, that is, the width direction of electrode sheet 11 and the length direction X of electrode sheet 11 are approximately perpendicular.

[0193] It should be noted that the tab 112 may include multiple tab layers. A tab layer refers to a ring-shaped structure formed by winding the tab 112 one turn, with each tab layer arranged around the outer periphery of the winding axis L. Here, winding the tab 112 one turn means that the tab 112 is wound approximately 360°. All tab layers are distributed sequentially along the radial direction Y, and all tab layers are also distributed sequentially and connected along the winding direction W, so that all tab layers form a wound structure, that is, the tab 112 is wound to form a wound structure.

[0194] The first electrode lug winding portion 1121 and the second electrode lug winding portion 1122 are two parts of the electrode lug 112 divided radially Y, and are sequentially connected along the winding direction W. Both the first electrode lug winding portion 1121 and the second electrode lug winding portion 1122 are arranged around the outer periphery of the winding axis L. The second electrode lug winding portion 1122 is located outside the first electrode lug winding portion 1121, meaning that it is located outside the first electrode lug winding portion 1121 in the radial Y direction; and also outside the first electrode lug winding portion 1121 in the winding direction W. In other words, the second electrode lug winding portion 1122 surrounds the outer periphery of the first electrode lug winding portion 1121 and is connected to it. Understandably, all the tab layers of the tab 112 can be divided into at least two parts along the radial Y direction, one part being the first tab winding portion 1121 and the other part being the second tab winding portion 1122.

[0195] As shown in Figures 6, 8 and 9, in the first direction Z, the size of the second electrode ear winding portion 1122 is larger than the size of the first electrode ear winding portion 1121, so that the second electrode ear winding portion 1122 can extend beyond the first electrode ear winding portion 1121 in a direction away from the electrode body 111.

[0196] The portion of the tab 112 that undergoes bending is generally the part of the tab 112 that is away from the electrode body 111 along the first direction Z. That is, the portion of the tab 112 that is away from the electrode body 111 along the first direction Z is bent to gather and aggregate into a stacked layer. Since the second tab winding portion 1122 extends beyond the first tab winding portion 1121 in the first direction Z, the tab 112 is primarily bent using the second tab winding portion 1122. It is understandable that the first tab winding portion 1121 is not bent; or, the degree of bending of the first tab winding portion 1121 is very weak. Thus, the binding effect of the first tab winding portion 1121 is weak, resulting in a weaker mutual binding effect between the first tab winding portion 1121 and the second tab winding portion 1122.

[0197] On the projection plane perpendicular to the first direction Z, the orthographic projection of the first pole lug winding portion 1121 is located within the orthographic projection of the pressure relief portion 22111, meaning that the area enclosed by the outer contour of the orthographic projection of the first pole lug winding portion 1121 is located within the area enclosed by the outer contour of the orthographic projection of the pressure relief portion 22111.

[0198] The exhaust channel refers to a channel that penetrates the wall of the outer casing 2 along the first direction Z, through which the pressure relief mechanism 2211 is formed, allowing at least a portion of the electrode 11 to be released outside the outer casing 2. When the pressure relief section 22111 is opened to form the exhaust channel, at least a portion of the electrode 11 can be positioned directly opposite the exhaust channel along the first direction Z, so that at least a portion of the electrode 11 can be released outside the outer casing 2 under the action of air pressure through the exhaust channel. The wall of the outer casing 2 with the pressure relief mechanism 2211 can be the first end wall 221 described below, that is, the first end wall 221 includes the pressure relief mechanism 2211.

[0199] The cylindrical battery cell 10 provided in this application embodiment includes a first electrode winding portion 1121 and a second electrode winding portion 1122 disposed outside the first electrode winding portion 1121 via an electrode assembly 1. The second electrode winding portion 1122 extends beyond the first electrode winding portion 1121 along the first direction Z away from the electrode body 111, thereby weakening the binding effect of the first electrode winding portion 1121 and the binding effect between the first electrode winding portion 1121 and the second electrode winding portion 1122. The outer casing 2 has a pressure relief portion 22111 at at least one end along the first direction Z. On the projection plane perpendicular to the first direction Z, the orthographic projection of the first electrode winding portion 1121 is located within the orthographic projection of the pressure relief portion 22111. This reduces the self-binding effect of the electrode 112 on at least a portion of the pressure relief portion 22111 (the first electrode winding portion 1121), thereby also reducing the binding effect of the electrode 11 on at least a portion of the pressure relief portion 22111. The pressure relief section 22111 is configured to at least partially open and form an exhaust channel during pressure relief. At least a portion of the electrode 11 is discharged outside the casing 2 through the exhaust channel. This allows the self-binding effect of the first electrode winding section 1121 and the binding effect between the first electrode winding section 1121 and the second electrode winding section 1122 to be easily broken under the action of air pressure during the thermal runaway of the cylindrical battery cell 10. As a result, at least a portion of the electrode 11 facing the pressure relief section 22111 can easily move towards the pressure relief section 22111 under the action of air pressure and be discharged outside the casing 2 through the exhaust channel formed by the opening of the pressure relief section 22111. This can reduce the obstruction effect of the electrode 112 on the high temperature and high pressure medium. During this process, on the one hand, the high-temperature and high-pressure medium generated inside the cylindrical battery cell 10 can be discharged out of the casing 2 along with the electrode 11. On the other hand, a large channel is formed in the area of ​​the electrode 11 facing the pressure relief section 22111, and this channel gradually increases in size as the electrode 11 is released, thus facilitating the discharge of the high-temperature and high-pressure medium. In this way, the discharge efficiency of the high-temperature and high-pressure medium can be improved, enabling the cylindrical battery cell 10 to achieve a highly efficient directional pressure relief effect, thereby helping to improve the reliability of the cylindrical battery cell 10.

[0200] In some embodiments, please refer to Figures 3 to 9 together with other figures. The electrode 11 includes a first electrode winding portion 114 and a second electrode winding portion 115 disposed outside the first electrode winding portion 114. A first electrode ear winding portion 1121 is formed at one end of the first electrode winding portion 114 along the first direction Z, and a second electrode ear winding portion 1122 is formed at one end of the second electrode winding portion 115 along the first direction Z. On a projection plane perpendicular to the first direction Z, the orthographic projection of the first electrode winding portion 114 lies within the orthographic projection of the pressure relief portion 22111. At least a portion of the first electrode winding portion 114 is released outside the housing 2 through the exhaust passage during pressure relief.

[0201] The first electrode winding portion 114 and the second electrode winding portion 115 are two parts of the electrode 11 divided along the radial direction Y, and are sequentially connected along the winding direction W. Both the first electrode winding portion 114 and the second electrode winding portion 115 are arranged around the outer periphery of the winding axis L. The second electrode winding portion 115 is located outside the first electrode winding portion 114, meaning that it is located outside the first electrode winding portion 114 in the radial direction Y; and also outside the first electrode winding portion 114 in the winding direction W. In other words, the second electrode winding portion 115 is arranged around the outer periphery of the first electrode winding portion 114 and is connected to it.

[0202] It should be noted that the electrode body 111 may include multiple electrode layers. An electrode layer refers to a ring-shaped structure formed by winding the electrode body 111 one turn, with each electrode layer arranged around the outer periphery of the winding axis L. Here, winding the electrode body 111 one turn means that the electrode body 111 is wound approximately 360°. All electrode layers are distributed sequentially along the radial direction Y, and all electrode layers are also distributed sequentially and connected along the winding direction W, so that all electrode layers form a wound structure, that is, the electrode body 111 is wound to form a wound structure. Among all tab layers and all electrode layers, each tab layer and each electrode layer is correspondingly arranged and connected along the first direction Z, so that the electrode 11 is wound to form multiple ring-shaped structures, thus forming a wound structure. The ring-shaped structure formed by the winding of the electrode 11 includes electrode layers and tab layers.

[0203] The first electrode lug winding portion 1121 is formed at one end of the first electrode winding portion 114 along the first direction Z, meaning that one end of the first electrode winding portion 114 along the first direction Z is the first electrode lug winding portion 1121. Specifically, in the first electrode winding portion 114, the electrode lug 112 portion is the first electrode lug winding portion 1121, the electrode body 111 portion is the first body winding portion 1112, and the first electrode lug winding portion 1121 and the first body winding portion 1112 are connected along the first direction Z.

[0204] The second electrode lug winding portion 1122 is formed at one end of the second electrode winding portion 115 along the first direction Z, meaning that one end of the second electrode winding portion 115 along the first direction Z is the second electrode lug winding portion 1122. Specifically, in the second electrode winding portion 115, the electrode lug 112 portion is the second electrode lug winding portion 1122, the electrode body 111 portion is the second body winding portion 1113, and the second electrode lug winding portion 1122 and the second body winding portion 1113 are connected along the first direction Z.

[0205] The first main body winding portion 1112 and the second main body winding portion 1113 are two parts of the electrode body 111 divided radially along the Y direction, and the first main body winding portion 1112 and the second main body winding portion 1113 are connected sequentially along the winding direction W. Both the first main body winding portion 1112 and the second main body winding portion 1113 are arranged around the outer periphery of the winding axis L. In the radial direction Y, the second main body winding portion 1113 is located outside the first main body winding portion 1112; and in the winding direction W, the second main body winding portion 1113 is located outside the first main body winding portion 1112. That is, the second main body winding portion 1113 is arranged around the outer periphery of the first main body winding portion 1112 and connected to the first main body winding portion 1112. It can be understood that all electrode layers of the electrode body 111 can be divided into at least two parts along the radial direction Y, one part being the first main body winding portion 1112 and the other part being the second main body winding portion 1113. The first main winding portion 1112 and the second main winding portion 1113 each include multiple electrode layers, and the first electrode tab winding portion 1121 and the second electrode tab winding portion 1122 each include multiple electrode tab layers. Each electrode layer of the first main winding portion 1112 and each electrode tab layer of the first electrode tab winding portion 1121 are correspondingly arranged and connected along the first direction Z. All electrode layers of the first main winding portion 1112 and all electrode tab layers of the first electrode tab winding portion 1121 constitute the first electrode winding portion 114. Each electrode layer of the second main winding portion 1113 and each electrode tab layer of the second electrode tab winding portion 1122 are correspondingly arranged and connected along the first direction Z. All electrode layers of the second main winding portion 1113 and all electrode tab layers of the second electrode tab winding portion 1122 constitute the second electrode winding portion 115.

[0206] On the projection plane perpendicular to the first direction Z, the orthographic projection of the first electrode winding portion 114 is located within the orthographic projection of the pressure relief portion 22111. This means that on the projection plane perpendicular to the first direction Z, the orthographic projections of the first electrode ear winding portion 1121 and the first main body winding portion 1112 are both located within the orthographic projection of the pressure relief portion 22111, so that the first electrode winding portion 114 and the pressure relief portion 22111 are arranged facing each other along the first direction Z.

[0207] By adopting the above technical solution, during the thermal runaway of the cylindrical battery cell 10, the self-binding effect of the first tab winding portion 1121 and the binding effect between the first tab winding portion 1121 and the second tab winding portion 1122 are easily broken under the action of air pressure. This allows the self-binding effect of the first electrode winding portion 114 and the binding effect between the first electrode winding portion 114 and the second electrode winding portion 115 to be easily broken under the action of air pressure. Consequently, at least a portion of the first electrode winding portion 114 is easily loosened under the action of air pressure and moves towards the pressure relief portion 22111, where it is released to the outside of the outer casing 2 through the exhaust channel formed by the opening of the pressure relief portion 22111. This improves the discharge efficiency of the high-temperature, high-pressure medium, enabling the cylindrical battery cell 10 to achieve a highly efficient directional pressure relief effect, thereby contributing to improved reliability of the cylindrical battery cell 10.

[0208] In some embodiments, please refer to Figures 7 to 9 together with other figures. At least one electrode 11 has a winding start end 104 and a winding end end 105 at both ends along the winding direction W of the electrode assembly 1.

[0209] A winding start end 104 and a winding end end 105 are respectively disposed at both ends of the electrode 11 along the winding direction W. The winding start end 104 is the end face of one end of the electrode 11 along the winding direction W, and the winding end end 105 is the end face of the other end of the electrode 11 along the winding direction W. In the radial direction Y of the electrode assembly 1, the winding end end 105 is disposed outside the winding start end 104, and the winding start end 104 is closer to the winding axis L than the winding end end 105.

[0210] It should be noted that both the positive electrode 11a and the negative electrode 11b can have a winding start end 104 and a winding end end 105.

[0211] In some embodiments, please refer to Figures 7 to 9 together with other figures. A winding start end 104 is formed in the first electrode winding portion 114, and a winding end end 105 is formed in the second electrode ear winding portion 1122.

[0212] Understandably, in the winding direction W, the end face of the first electrode winding portion 114 away from the second electrode winding portion 115 is the winding start end 104, and the end face of the second electrode winding portion 115 away from the first electrode winding portion 114 is the winding end end 105. Specifically, in the first electrode winding portion 114, both the first electrode ear winding portion 1121 and the first main body winding portion 1112 have a winding start end 104. In the second electrode winding portion 115, both the second electrode ear winding portion 1122 and the second main body winding portion 1113 have a winding end 105.

[0213] The first electrode winding portion 114 is formed by the winding start end 104, and the orthographic projection of the first electrode winding portion 114 is located within the orthographic projection of the pressure relief portion 22111 on the projection plane perpendicular to the first direction Z. Based on this, during thermal runaway, when at least a portion of the pressure relief portion 22111 opens to form an exhaust channel, the portion of the first electrode winding portion 114 near the winding start end 104 and the exhaust channel are directly opposite each other along the first direction Z. This facilitates the release of at least a portion of the electrode 11 near the winding start end 104 to the outside of the casing 2 through the exhaust channel, allowing at least a portion of the electrode 11 to loosen under pressure and release through the exhaust channel, thus improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0214] In some embodiments, please refer to Figures 4, 5, and 7 together, and in conjunction with other figures. The electrode assembly 1 has a central hole 101 extending along a first direction Z, and a first electrode winding portion 114 is disposed around the outer periphery of the central hole 101. On a projection plane perpendicular to the first direction Z, the orthographic projection of the central hole 101 lies within the orthographic projection of the pressure relief portion 22111.

[0215] The electrode assembly 1 has a central hole 101 extending along the first direction Z, meaning that the central hole 101 passes through both ends of the electrode assembly 1 along the first direction Z. In the radial direction Y of the electrode assembly 1, the winding start end 104 is closer to the central hole 101 than the winding end end 105.

[0216] The first electrode winding portion 114 is arranged around the outer periphery of the central hole 101, such that the first electrode ear winding portion 1121 and the first main body winding portion 1112 are both arranged around the outer periphery of the central hole 101. The second electrode winding portion 115 is arranged around the outer periphery of the central hole 101, such that the second electrode ear winding portion 1122 and the second main body winding portion 1113 are both arranged around the outer periphery of the central hole 101.

[0217] On the projection plane perpendicular to the first direction Z, the orthographic projection of the central hole 101 is located within the orthographic projection of the pressure relief part 22111. This means that on the projection plane perpendicular to the first direction Z, the area enclosed by the outer contour of the orthographic projection of the central hole 101 is located within the area enclosed by the outer contour of the orthographic projection of the pressure relief part 22111.

[0218] By placing the orthographic projection of the central hole 101 within the orthographic projection of the pressure relief portion 22111 on a projection plane perpendicular to the first direction Z, the central hole 101 and the pressure relief portion 22111 are positioned directly opposite each other along the first direction Z. This allows at least a portion of the electrode 11 adjacent to the central hole 101 to be positioned directly opposite the pressure relief portion 22111 along the first direction Z, and at least a portion of the central hole 101 can be aligned with and connected to the exhaust channel formed by the opening of the pressure relief portion 22111 along the first direction Z. Thus, during the thermal runaway of the cylindrical battery cell 10, at least a portion of the first electrode winding portion 114 opposite the pressure relief portion 22111 can move towards the central hole 101 under the action of air pressure, and loosen using the space of the central hole 101, allowing at least a portion of the electrode 11 adjacent to the central hole 101 to loosen under the action of air pressure. Furthermore, at least a portion of the electrode 11 adjacent to the central hole 101 loosens under air pressure, allowing it to gradually release pressure through the exhaust channel formed by the pressure relief section 22111 to the outside of the outer casing 2. Thus, the central hole 101 facilitates the loosening of the electrode 11 under air pressure and allows it to release pressure to the outside of the outer casing 2, thereby facilitating exhaust and achieving a highly efficient directional pressure relief effect.

[0219] It should be further noted that during the process of at least a portion of the electrode 11 adjacent to the central hole 101 being vented to the outside of the housing 2 through the venting channel, at least a portion of the electrode 11 near the winding start end 104 will also be vented to the outside of the housing 2 through the venting channel. This facilitates the loosening of at least a portion of the electrode 11 adjacent to the central hole 101 and allows for venting through the venting channel, thereby improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0220] During the process of venting pressure through the venting channel formed by the pressure relief section 22111 on electrode 11, the space at the central hole 101 gradually increases as electrode 11 vents. This can be understood as the aperture of the central hole 101 gradually increasing as electrode 11 vents. This facilitates the discharge of high-temperature, high-pressure media through the central hole 101, improving the problem of low exhaust rate caused by an excessively small aperture of the central hole 101, thus achieving a highly efficient directional pressure relief effect.

[0221] In some embodiments, please refer to FIG4, and in conjunction with other figures. The outer diameter of electrode assembly 1 is D1, and the diameter of central hole 101 is D2, where D2 / D1 ∈ [5%, 25%].

[0222] Wherein, D2 / D1 can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc.

[0223] This design allows the central hole 101 to have a large aperture, which facilitates the discharge of the high-temperature and high-pressure medium inside the cylindrical battery cell 10 to the pressure relief section 22111 through the central hole 101 during thermal runaway, thereby achieving a highly efficient directional pressure relief effect.

[0224] In some embodiments, please refer to FIG13, and in conjunction with other figures. FIG13 is an enlarged view of point E in FIG4. In FIG13, the tab 112 and the electrode body 111 are divided by dashed lines. The electrode assembly 1 has a winding axis L parallel to the first direction Z, and the second tab winding portion 1122 has a bent section 112211 at one end in the first direction Z.

[0225] The bent section 112211 is the portion of the second electrode ear winding portion 1122 that is bent relative to the electrode body 111. Specifically, the bent section 112211 is formed at the end of the second electrode ear winding portion 1122 that is away from the electrode body 111 along the first direction Z.

[0226] In some possible designs, as shown in Figure 13 and in conjunction with other figures, the bent segment 112211 includes a first bent portion 1122111, which is bent relative to the electrode body 111 in a direction close to the winding axis L.

[0227] The first bending portion 1122111 refers to the part of the bending section 112211 that is bent relative to the electrode body 111 toward the winding axis L.

[0228] In some possible designs, as shown in Figure 13 and in conjunction with other figures, the bent segment 112211 includes a second bent portion 1122112, which is bent relative to the electrode body 111 in a direction away from the winding axis L.

[0229] The second bending section 1122112 refers to the part of the bending section 112211 that is bent away from the winding axis L relative to the electrode body 111.

[0230] This configuration allows the end region of the tab 112 facing away from the electrode body 111 along the first direction Z to be bent, thereby gathering and assembling together to form a relatively dense stacked layer. This facilitates, on the one hand, welding the second tab winding portion 1122 of the tab 112 to the current collector 3 described below. On the other hand, it provides a stronger binding effect on the electrode 11, resulting in higher charge-discharge performance of the electrode assembly 1.

[0231] It should be further clarified that the first bending portion 1122111 is bent in the direction close to the winding axis L, meaning that the first bending portion 1122111 is bent in the direction close to the center hole 101. The second bending portion 1122112 is bent in the direction away from the winding axis L, meaning that the second bending portion 1122112 is bent in the direction away from the center hole 101.

[0232] In some embodiments, please refer to FIG7 and other figures. In the winding direction W of the electrode assembly 1, the length of the second electrode lug winding portion 1122 is greater than the length of the first electrode lug winding portion 1121.

[0233] This configuration allows the winding structure formed by the second electrode lug winding portion 1122 to have a large area for welding with the current collector 3 described below. This can, to a certain extent, ensure the welding stability of the current collector 3 and the electrode lug 112. Furthermore, the end region of the second electrode lug winding portion 1122 away from the electrode body can be bent to form a large accumulation layer, which can, to a certain extent, ensure the overall binding effect of the electrode 11, thereby ensuring the structural integrity and performance of the electrode assembly 1.

[0234] In some embodiments, please refer to Figures 4 to 6 and Figure 10 together, and in conjunction with other figures. Figure 10 is an enlarged view of point D in Figure 4. In Figure 10, the first electrode lug winding portion 1121 and the second electrode lug winding portion 1122 are divided by dashed lines. Both electrode plates 11 include an electrode plate body 111 and an electrode lug 112. The electrode lugs 112 of the two electrode plates 11 are respectively disposed at both ends of the electrode assembly 1 along the first direction Z. Each electrode lug 112 of the two electrode plates 11 includes a first electrode lug winding portion 1121 and a second electrode lug winding portion 1122. On a projection plane perpendicular to the first direction Z, the orthographic projection of the first electrode lug winding portion 1121 of the electrode lug 112 of each electrode plate 11 is located within the orthographic projection of the pressure relief portion 22111.

[0235] Understandably, the two electrodes 11 are a positive electrode 11a and a negative electrode 11b, respectively. Both the positive electrode 11a and the negative electrode 11b include an electrode body 111 and a tab 112. Specifically, the electrode body 111 of the positive electrode 11a is the first electrode body 111a, and the tab 112 of the positive electrode 11a is the positive electrode tab 112a. The electrode body 111 of the negative electrode 11b is the second electrode body 111b, and the tab 112 of the negative electrode 11b is the negative electrode tab 112b. The first electrode body 111a, the second electrode body 111b, and the diaphragm 12 constitute the main body P of the electrode assembly 1. The positive electrode tab 112a and the negative electrode tab 112b are respectively disposed at both ends of the electrode assembly 1 along the first direction Z, specifically at both ends of the main body P along the first direction Z. On the projection plane perpendicular to the first direction Z, the orthographic projection of the first electrode winding portion 1121 of the positive electrode tab 112a and the orthographic projection of the first electrode winding portion 1121 of the negative electrode tab 112b are both located within the orthographic projection of the pressure relief portion 22111.

[0236] Specifically, on the projection plane perpendicular to the first direction Z, the orthographic projection of the first electrode winding portion 114 of each electrode 11 is located within the orthographic projection of the pressure relief portion 22111. Specifically, on the projection plane perpendicular to the first direction Z, the orthographic projections of the first electrode winding portion 114 of both the positive electrode 11a and the negative electrode 11b are located within the orthographic projection of the pressure relief portion 22111.

[0237] Furthermore, in the positive electrode tab 112a, in the first direction Z, the second electrode tab winding portion 1122 extends beyond the first electrode tab winding portion 1121 in a direction away from the electrode body 111. In the negative electrode tab 112b, in the first direction Z, the second electrode tab winding portion 1122 extends beyond the first electrode tab winding portion 1121 in a direction away from the electrode body 111.

[0238] For ease of description, in the two electrode plates 11, the tab 112 of one electrode plate 11 is defined as the first tab, and the tab 112 of the other electrode plate 11 is defined as the second tab. The first tab and the second tab are respectively disposed at both ends of the electrode assembly 1 along the first direction Z, and both the first tab and the second tab include a first tab winding portion 1121 and a second tab winding portion 1122. On the projection plane perpendicular to the first direction Z, the orthographic projection of the first tab winding portion 1121 of the first tab and the first tab winding portion 1121 of the second tab are both located within the orthographic projection of the pressure relief portion 22111. In the first direction Z, the second tab winding portion 1122 extends beyond the first tab winding portion 1121 in a direction away from the electrode plate body 111.

[0239] The first electrode can be a positive electrode 112a and the second electrode can be a negative electrode 112b; or the first electrode can be a negative electrode 112b and the second electrode can be a positive electrode 112a.

[0240] By adopting the above technical solution, the binding effect of the first electrode winding portion 1121 and the binding effect between the first electrode winding portion 1121 and the second electrode winding portion 1122 in the positive electrode tab 112a and negative electrode tab 112b are weakened. In this way, the binding effect of the positive electrode 11a itself, the binding effect of the negative electrode 11b itself, and the mutual binding effect between the positive electrode 11a and the negative electrode 11b can all be reduced. During the thermal runaway of the cylindrical battery cell 10, the self-binding effect of the first tab winding portion 1121 and the binding effect between the first tab winding portion 1121 and the second tab winding portion 1122 in the positive electrode tab 112a and negative electrode tab 112b are easily broken under the action of air pressure. This allows at least a portion of the positive electrode 11a facing the pressure relief portion 22111 and at least a portion of the negative electrode 11b facing the pressure relief portion 22111 to loosen under the action of air pressure and release pressure through the exhaust channel formed by the opening of the pressure relief portion 22111 to the outside of the outer casing 2. This arrangement facilitates the release of pressure through the exhaust channel to the outside of the outer casing 2 for at least a portion of the electrode assembly 1 facing the pressure relief portion 22111, achieving a highly efficient directional pressure relief effect and thus contributing to the reliability of the cylindrical battery cell 10.

[0241] In some embodiments, please refer to Figures 11 and 12 together, and in conjunction with other figures. Figure 11 is a partially unfolded schematic diagram of the positive electrode 11a of the cylindrical battery cell 10 provided in Figure 3. In Figure 11, both the insulating layer 113 and the active material layer 1111 are shown in cross-section. Figure 12 is a partially unfolded schematic diagram of the negative electrode 11b of the cylindrical battery cell 10 provided in Figure 3. In Figure 12, the active material layer 1111 is shown in cross-section. The electrode body 111 includes a current collector and an active material layer 1111 coated on the current collector. Specifically, the active material layer 1111 is coated on the surface of the current collector along its thickness direction. The current collector is a conductive structure, and the current collector and the tab 112 are electrically connected.

[0242] In the positive electrode 11a, the current collector may be, but is not limited to, aluminum foil. In the negative electrode 11b, the current collector may be, but is not limited to, copper foil.

[0243] In some embodiments, please refer to Figures 11 and 12 together, and in conjunction with other figures. The two electrodes 11 include a positive electrode 11a and a negative electrode 11b.

[0244] In some possible designs, as shown in Figure 11 and in conjunction with other figures, the tab 112 of the positive electrode 11a is not coated with an active material layer 1111.

[0245] Understandably, the positive electrode 11a includes a first electrode body 111a and a positive electrode tab 112a. The current collector and the positive electrode tab 112a are electrically connected.

[0246] The first electrode body 111a can be completely coated with the active material layer 1111, that is, the current collector is completely coated with the active material layer 1111; and the positive electrode tab 112a is completely uncoated with the active material layer 1111. Based on this, in the first direction Z, the edge of the active material layer 1111 near the positive electrode tab 112a is the boundary between the first electrode body 111a and the positive electrode tab 112a, that is, in the positive electrode 11a, the part coated with the active material layer 1111 is the first electrode body 111a, and the part uncoated with the active material layer 1111 is the positive electrode tab 112a. Alternatively, the positive electrode tab 112a is not coated with the active material layer 1111 at all, and in the first direction Z, the end region of the first electrode body 111a near the positive electrode tab 112a is not coated with the active material layer 1111, while the rest of the first electrode body 111a is coated with the active material layer 1111; that is, one part of the current collector is coated with the active material layer 1111, and the other part is not coated with the active material layer 1111.

[0247] In some possible designs, please refer to Figure 12, and in conjunction with other figures. The tab 112 of the negative electrode 11b is not coated with the active material layer 1111.

[0248] Understandably, the negative electrode 11b includes a second electrode body 111b and a negative electrode tab 112b. The current collector and the negative electrode tab 112b are electrically connected.

[0249] The second electrode body 111b can be completely coated with the active material layer 1111, that is, the current collector is completely coated with the active material layer 1111; and the negative electrode tab 112b is completely uncoated with the active material layer 1111. Based on this, in the first direction Z, the edge of the active material layer 1111 near the negative electrode tab 112b is the boundary between the second electrode body 111b and the negative electrode tab 112b, that is, in the negative electrode 11b, the part coated with the active material layer 1111 is the second electrode body 111b, and the part uncoated with the active material layer 1111 is the negative electrode tab 112b. Alternatively, the negative electrode tab 112b is not coated with the active material layer 1111 at all, and in the first direction Z, the end region of the second electrode body 111b near the negative electrode tab 112b is not coated with the active material layer 1111, while the remaining part of the second electrode body 111b is coated with the active material layer 1111; that is, one part of the current collector is coated with the active material layer 1111, and the other part is not coated with the active material layer 1111.

[0250] Thus, the tab 112 is not coated with an active material layer 1111.

[0251] In some embodiments, please refer to Figures 4 through 10 together with other figures. The cylindrical battery cell 10 also includes a current collector 3, at least a portion of which is disposed within the housing 2. The current collector 3 is welded to the second tab winding portion 1122, but not to the first tab winding portion 1121.

[0252] The current collector 3 is a component with conductive properties, mainly used for welding to the tab 112 to achieve current collection for the electrode assembly 1. Specifically, the current collector 3 can be a transition structure between the current transmission end of the cylindrical battery cell 10 and the electrode assembly 1. The current collector 3 is welded to the tab 112 to achieve electrical connection between the current collector 3 and the electrode assembly 1. The current collector 3 can also be electrically connected to the current transmission end, thereby achieving electrical connection between the current transmission end and the electrode assembly 1.

[0253] Among them, the current collection component 3 may be, but is not limited to, a current collection disk.

[0254] The current transmission terminal of the cylindrical battery cell 10 refers to the component used to transmit the current of the cylindrical battery cell 10, specifically for outputting or inputting current. The current transmission terminal may include the electrode terminals 5 described below, or it may include the housing 2. The current transmission terminal includes a positive current transmission terminal and a negative current transmission terminal.

[0255] The current collector 3 is welded to the second tab winding portion 1122 of the tab 112, which is the tab layer of the current collector 3 welded to the second tab winding portion 1122. Specifically, it can be welded to the section 11221 mentioned below on the second tab winding portion 1122. The current collector 3 is welded to the second tab winding portion 1122, so that the second tab winding portion 1122 can achieve a certain self-binding effect through welding, thereby achieving a strong binding effect on the electrode sheet 11 as a whole, so as to a certain extent ensuring the structural integrity of the electrode assembly 1 and facilitating the charging and discharging performance of the electrode assembly 1. Correspondingly, the current collector 3 is not welded to the first electrode ear winding portion 1121, so that the current collector 3 basically does not play a role in binding the first electrode ear winding portion 1121, thereby making the self-binding effect of the first electrode ear winding portion 1121 weak, and the self-binding effect of the portion of the electrode 11 where the first electrode ear winding portion 1121 is formed (the first electrode winding portion 114) will also be weakened.

[0256] The first electrode ear winding portion 1121 can be spaced apart from the current collector 3 along the first direction Z, as shown in Figure 6; or, the first electrode ear winding portion 1121 can be in contact with the current collector 3.

[0257] Specifically, the current collector 3 and the tab 112 are arranged generally along the first direction Z. That is, the current collector 3 is provided between at least one wall of the housing 2 along the first direction Z and the electrode assembly 1. As an example, as shown in FIG4, the electrode assembly 1 has tabs 112 formed at both ends along the first direction Z, and the current collector 3 is provided at both ends along the first direction Z. The current collector 3 at each end is welded to the second tab winding portion 1122 of the tab 112 at each end. As another example, the electrode assembly 1 has a current collector 3 at one end along the first direction Z. It can be understood that the current collector 3 and the tab 112 can be strictly distributed along the first direction Z, and at least a portion of the tab 112 can also be inserted into the current collector 3.

[0258] As shown in Figure 4, electrode assembly 1 has tabs 112 at both ends along the first direction Z, and current collectors 3 at both ends along the first direction Z. The current collectors 3 at each end are welded to the second tab winding portion 1122 of the tabs 112 at each end. Alternatively, the current collector 3 is provided at one end of electrode assembly 1 along the first direction Z.

[0259] The current collector 3 is welded to the second electrode winding portion 1122, but not to the first electrode winding portion 1121, which weakens the self-binding effect of the first electrode winding portion 1121. Thus, during thermal runaway of the cylindrical battery cell 10, at least a portion of the electrode sheet 11 with the first electrode winding portion 1121 can loosen under pressure and be released outside the casing 2 through the exhaust channel formed by the pressure relief portion 22111. This improves the directional pressure relief effect of the cylindrical battery cell 10 and helps to enhance its reliability.

[0260] In some embodiments, please refer to Figures 4 and 10 together, and in conjunction with other figures. The cylindrical battery cell 10 also includes electrode terminals 5, which are fixed to the housing 2.

[0261] Electrode terminal 5 refers to a component with conductive properties. Electrode terminal 5 serves as the current transmission terminal of the cylindrical battery cell 10 and is used to transmit current. Electrode terminal 5 may be, but is not limited to, a terminal post.

[0262] Electrode terminal 5 may be welded to current collector 3 welded to positive electrode tab 112a to achieve electrical connection between electrode terminal 5 and positive electrode tab 112a; electrode terminal 5 may also be welded to current collector 3 welded to negative electrode tab 112b to achieve electrical connection between electrode terminal 5 and negative electrode tab 112b.

[0263] The number of electrode terminals 5 can be one. As an example, as shown in Figure 4, an electrode terminal 5 is installed on the wall of one end of the housing 2 along the first direction Z. A current collector 3 is provided at the end of the electrode assembly 1 along the first direction Z near the electrode terminal 5. The current collector 3 is welded to the tab 112 at that end, and the current collector 3 is also welded to the electrode terminal 5. For example, as shown in Figure 4, in the first direction Z, a first current collector 3a is disposed between the first tab and the electrode terminal 5. The first current collector 3a is welded to the second tab winding portion 1122 of the first tab, and the first current collector 3a is welded to the electrode terminal 5.

[0264] Alternatively, there can be two electrode terminals 5, one a positive electrode terminal and the other a negative electrode terminal. The positive and negative electrode terminals can be located at one end of the housing 2, or at both ends of the housing 2. As an example, electrode terminals 5 are provided on the walls of both ends of the housing 2 along the first direction Z, and electrode assembly 1 has tabs 112 and current collectors 3 at both ends along the first direction Z. In the first direction Z, the tabs 112 at each end are welded to the corresponding current collectors 3, and the electrode terminals 5 are welded to the corresponding current collectors 3.

[0265] The electrode terminal 5 is mounted on the housing 2. Specifically, as shown in Figure 4, the electrode terminal 5 can be disposed on the housing 21 of the housing 2. The electrode terminal 5 can also be disposed on the end cover 22 of the housing 2.

[0266] When there are two electrode terminals 5, the two electrode terminals 5 can be simultaneously disposed on the housing 21; or, the two electrode terminals 5 can be simultaneously disposed on the end cover 22; or, one of the two electrode terminals 5 can be disposed on the housing 21 and the other can be disposed on the end cover 22.

[0267] In some embodiments, please refer to Figures 10 and 17 together, and in conjunction with other figures. Figure 17 is a projected schematic diagram of the electrode assembly 1, current collector 3, and electrode terminal 5 of the cylindrical battery cell 10 provided in Figure 3. Specifically, it is a schematic diagram of the orthographic projection of the electrode assembly 1, the current collector 3, and the electrode terminal 5 on a projection plane perpendicular to the first direction Z. In Figure 17, the regions shown by the cross-sectional lines are the first transverse region M5 and the second transverse region N5, respectively. The first arc line M3, the second arc line M4, the third arc line N3, and the third arc line N3 are all dashed lines. The electrode terminal 5 is welded to the current collector 3 to form a first welded portion 4.

[0268] The first welded part 4 refers to the weld mark formed by welding the electrode terminal 5 and the current collector 3.

[0269] As an example, as shown in Figure 17, on a projection plane perpendicular to the first direction Z, the orthographic projection of the first welded portion 4 is approximately circular and is arranged around the outer periphery of the central hole 101. As another example, there are multiple first welded portions 4. On a projection plane perpendicular to the first direction Z, the orthographic projections of multiple first welded portions 4 are spaced apart along the circumferential direction E, and the orthographic projections of multiple first welded portions 4 are arranged together around the outer periphery of the central hole 101.

[0270] This configuration allows for electrical connection between electrode terminal 5 and electrode assembly 1.

[0271] In some embodiments, please refer to FIG10, and in conjunction with other figures. In the radial Y direction of the electrode assembly 1, the first welding portion 4 is located outside the first electrode lug winding portion 1121.

[0272] By providing a first welding portion 4 on the outer side of the first tab winding portion 1121 in the radial Y direction of the electrode assembly 1, the first welding portion 4 is not formed on the first tab winding portion 1121. This allows the portion of the tab 112 with the first welding portion 4 to support the welding penetration depth of the current collector 3 and the electrode terminal 5, thus improving the problem of laser penetration of the tab 112 and burning of the diaphragm 12 during the welding process of the current collector 3 and the electrode terminal 5. In this way, the short-circuit problem of the electrode assembly 1 can be improved, and the risk of short circuit can be reduced.

[0273] In some embodiments, please refer to Figures 4 to 6 and Figure 10 together, and in conjunction with other figures. In the first direction Z, both ends of the electrode assembly 1 are provided with current collectors 3, and the current collectors 3 at both ends of the electrode assembly 1 are a first current collector 3a and a second current collector 3b, respectively. The first current collector 3a is welded to the second electrode winding portion 1122 of the first electrode tab, and the second current collector 3b is welded to the second electrode winding portion 1122 of the second electrode tab.

[0274] The first current collector 3a and the second current collector 3b are respectively disposed at both ends of the electrode assembly 1 along the first direction Z. Specifically, the first current collector 3a is disposed at the end of the electrode assembly 1 where the first tab is formed along the first direction Z, and is disposed between the wall of the outer casing 2 along the first direction Z and the first tab. The second current collector 3b is disposed at the end of the electrode assembly 1 where the second tab is formed along the first direction Z, and is disposed between the wall of the outer casing 2 along the first direction Z and the second tab.

[0275] Both the first electrode ear and the second electrode ear include a first electrode ear winding portion 1121 and a second electrode ear winding portion 1122, such that both electrode plates 11 have a first electrode plate winding portion 114.

[0276] Understandably, the first current collector 3a is welded to the second electrode winding portion 1122 of the first electrode ear, but not to the first electrode winding portion 1121 of the first electrode ear. The second current collector 3b is welded to the second electrode winding portion 1122 of the second electrode ear, but not to the first electrode winding portion 1121 of the second electrode ear.

[0277] Specifically, the first current collector 3a is welded to the section 11221 (described below) of the second electrode winding portion 1122 of the first electrode tab to form the second weld portion 6 (described below). The second current collector 3b is welded to the section 11221 (described below) of the second electrode winding portion 1122 of the second electrode tab to form the second weld portion 6 (described below). It can be understood that both the first electrode tab and the second electrode tab have the second weld portion 6 (described below).

[0278] It should be noted that the current collectors 3 located at both ends of the electrode assembly 1 are the first current collector 3a and the second current collector 3b, respectively. This means that in the first direction Z, the first current collector 3a and the second current collector 3b are approximately located at both ends of the electrode assembly 1, that is, the first current collector 3a and the second current collector 3b are located at both ends of the main part of the electrode assembly 1. The first current collector 3a and the second current collector 3b can be precisely positioned at both ends of the electrode assembly 1 along the first direction Z. The tabs of the electrode assembly 1 can also partially pass through the first current collector 3a and the second current collector 3b, and be welded to the first current collector 3a and the second current collector 3b respectively.

[0279] The second electrode winding portion 1122 of the first electrode tab is welded to the first electrode tab by the first current collector 3a, but not to the first electrode winding portion 1121 of the first electrode tab, resulting in a weaker self-binding effect of the first electrode winding portion 1121 of the first electrode tab. Similarly, the second electrode winding portion 1122 of the second electrode tab is welded to the second electrode tab by the second current collector 3b, but not to the first electrode winding portion 1121 of the second electrode tab, resulting in a weaker self-binding effect of the first electrode winding portion 1121 of the second electrode tab. Therefore, the self-binding effect of the portions of the two electrode sheets 11 with the first electrode winding portions 1121 is weak. During the thermal runaway of the cylindrical battery cell 10, at least a portion of both electrode sheets 11 can loosen under pressure and be released outside the casing 2 through the exhaust channel formed by the pressure relief portion 22111. This configuration allows at least a portion of the electrode assembly 1 facing the pressure relief section 22111 to be released outside the housing 2 through the exhaust channel under the action of air pressure, thereby achieving an efficient directional pressure relief effect and contributing to the reliability of the cylindrical battery cell 10.

[0280] In some embodiments, please refer to Figures 4, 6, and 10 together, and in conjunction with other figures. The housing 2 includes a first end wall 221, a second end wall 211, and a side wall 212. The first end wall 221 and the second end wall 211 are respectively disposed at both ends of the side wall 212 along a first direction Z, and an electrode terminal 5 is provided on the second end wall 211. A first electrode tab is electrically connected to the electrode terminal 5 through a first current collector 3a, and a second electrode tab is electrically connected to the side wall 212 through a second current collector 3b.

[0281] The solid wall at one end of the outer casing 2 along the first direction Z is the first end wall 221, and the solid wall at the other end of the outer casing 2 along the first direction Z is the second end wall 211. In the first direction Z, the side wall 212 is disposed between the first end wall 221 and the second end wall 211, and is connected to the first end wall 221 and the second end wall 211.

[0282] The first end wall 221 may be a part of the housing 21; or, as shown in Figures 4 and 6, the first end wall 221 may be at least a part of the end cap 22.

[0283] The second end wall 211 may be at least a portion of the end cap 22; or, as shown in Figures 4 and 10, the second end wall 211 may be a portion of the housing 21.

[0284] As shown in Figures 4, 6 and 10, the sidewall 212 is part of the shell 21 and has electrical conductivity.

[0285] The first end wall 221, the second end wall 211, and the side wall 212 define the internal environment of the cylindrical battery cell 10, and the electrode assembly 1, the first current collector 3a, and the second current collector 3b are all disposed in the internal environment formed by the first end wall 221, the second end wall 211, and the side wall 212.

[0286] The first electrode tab and the first current collector 3a are electrically connected, and the first current collector 3a is electrically connected to the electrode terminal 5, so that the first electrode tab is electrically connected to the electrode terminal 5 through the first current collector 3a. In the first direction Z, the first current collector 3a may be disposed between the first electrode tab and the second end wall 211.

[0287] The second electrode tab is electrically connected to the second current collector 3b, and the second current collector 3b is electrically connected to the side wall 212, so that the second electrode tab is electrically connected to the side wall 212 through the second current collector 3b. In the first direction Z, the second current collector 3b may be disposed between the second electrode tab and the first end wall 221.

[0288] The first current collector 3a is welded to the second electrode winding portion 1122 of the first electrode tab to achieve electrical connection between the first current collector 3a and the first electrode tab. The second current collector 3b is welded to the second electrode winding portion 1122 of the second electrode tab to achieve electrical connection between the second current collector 3b and the second electrode tab.

[0289] The first current collector 3a and the electrode terminal 5 may be welded, but are not limited to, so as to achieve electrical connection between the first current collector 3a and the electrode terminal 5.

[0290] In this configuration, the second current collector 3b and the side wall 212 can be in direct contact to achieve an electrical connection between them; as an example, the second current collector 3b and the side wall 212 are welded together. Alternatively, other intermediate components can be provided between the second current collector 3b and the side wall 212 to achieve an electrical connection between them; as an example, this intermediate component is a first end wall 221, which has conductive properties, and the second current collector 3b is welded to the first end wall 221, and the first end wall 221 is also welded to the side wall 212.

[0291] In some possible designs, the first end wall 221 may be conductive, and the side wall 212 may be electrically connected to the first end wall 221. For example, the side wall 212 may be a part of the housing 21, and the first end wall 221 may be at least a part of the end cap 22. The first end wall 221 and the side wall 212 may be welded, specifically, the first wall 2212 of the first end wall 221 and the side wall 212 may be welded together to make the side wall 212 and the first end wall 221 electrically connected.

[0292] In some possible designs, the second end wall 211 may be conductive, and the side wall 212 may be electrically connected to the second end wall 211. For example, the second end wall 211 and the side wall 212 are two parts of the housing 21, and the second end wall 211 and the housing 21 are integrally formed so that the side wall 212 and the second end wall 211 are electrically connected. The second end wall 211 is insulated from the electrode terminal 5; for example, an insulating component such as insulating glue or plastic is provided between the second end wall 211 and the electrode terminal 5.

[0293] By adopting the above technical solution, at least one of the side wall 212, the first end wall 221, and the second end wall 211 can serve as one current transmission terminal of the cylindrical battery cell 10, and the electrode terminal 5 serves as the other current transmission terminal of the cylindrical battery cell 10. That is, the electrode terminal 5 and the outer casing 2 can serve as two current transmission terminals of the cylindrical battery cell 10.

[0294] When the second end wall 211 and the electrode terminal 5 serve as the two current transmission ends of the cylindrical battery cell 10, the two current transmission ends of the cylindrical battery cell 10 can be located at the same end. This facilitates the assembly process of assembling the cylindrical battery cell 10 into the battery device 100 and improves the efficiency of assembling multiple cylindrical battery cells 10 into a group.

[0295] In some embodiments, please refer to Figures 4 and 6 together, and in conjunction with other figures. The first end wall 221 is welded to the second current collector 3b, and the first end wall 221 is electrically connected to the side wall 212.

[0296] Understandably, both the first end wall 221 and the side wall 212 are conductive. The second current collector 3b can be, but is not limited to, welded to the first end wall 221 to achieve an electrical connection between the second current collector 3b and the first end wall 221. The side wall 212 can be electrically connected to the first end wall 221 by means of welding or other methods, thereby achieving an electrical connection between the second current collector 3b and the side wall 212.

[0297] This configuration allows the second current collector 3b to be indirectly electrically connected to the side wall 212 via the first end wall 221.

[0298] In some embodiments, please refer to FIG. 20, and in conjunction with other figures. FIG. 20 is a partial cross-sectional view of a cylindrical battery cell 10 provided in other embodiments of this application. In the radial Y direction of the electrode assembly 1, a protrusion 2121 is formed inwardly on the sidewall 212. The protrusion 2121 and the electrode assembly 1 are distributed along a first direction Z. A second current collector 3b is welded to the side of the protrusion 2121 near the electrode assembly 1, as shown in FIG. 20; or, the second current collector 3b is welded to the side of the protrusion 2121 away from the electrode assembly 1.

[0299] Understandably, the outer peripheral wall of the side wall 212 is provided with a groove 202. The groove 202 is provided so that the side wall 212 protrudes inward along the radial Y direction, thereby forming a protrusion 2121 on the side wall 212.

[0300] The protrusion 2121 can be distributed along the first direction Z with the electrode assembly 1, so that the protrusion 2121 can limit the electrode assembly 1 along the first direction Z. In the first direction Z, the second current collector 3b can be generally disposed between the electrode assembly 1 and the protrusion 2121, and welded to the side of the protrusion 2121 close to the electrode assembly 1; or, in the first direction Z, the second current collector 3b can also be generally disposed on the side of the protrusion 2121 away from the electrode assembly 1, and welded to the side of the protrusion 2121 away from the electrode assembly 1.

[0301] This configuration allows the second current collector 3b to be directly electrically connected to the side wall 212.

[0302] In some embodiments, please refer to Figures 4, 6, and 10 together, and in conjunction with other figures. A pressure relief portion 22111 is provided on the first end wall 221.

[0303] Understandably, the first end wall 221 includes the first wall 2212 and the pressure relief mechanism 2211 described below. The pressure relief mechanism 2211 is connected to the first wall 2212 and includes a pressure relief portion 22111. The first wall 2212 and the pressure relief mechanism 2211 may be integrally formed; alternatively, the first wall 2212 and the pressure relief mechanism 2211 may be separately formed and connected.

[0304] By adopting the above technical solution, the pressure relief part 22111 and the electrode terminal 5 are respectively located at both ends of the outer casing 2 along the first direction Z, which facilitates the layout of the pressure relief part 22111 and the electrode terminal 5 and helps to improve the efficiency of assembling multiple cylindrical battery cells 10 into a group.

[0305] In some embodiments, please refer to Figures 4 and 6 together, and in conjunction with other figures. The first electrode tab is a positive electrode tab 112a, and the second electrode tab is a negative electrode tab 112b.

[0306] Based on this, electrode terminal 5 is a positive electrode terminal, serving as the positive current transmission terminal of the cylindrical battery cell 10; the positive electrode terminal is electrically connected to the first current collector 3a, and the first current collector 3a is welded to the positive electrode tab 112a. At least one of the first end wall 221, the second end wall 211, and the side wall 212 is the negative current transmission terminal of the cylindrical battery cell 10, and the second current collector 3b is welded to the negative electrode tab 112b.

[0307] As an example, both the side wall 212 and the first end wall 221 can be made of steel.

[0308] By adopting the above technical solution, the electrode terminal 5 is a positive electrode terminal, and at least one of the first end wall 221, the second end wall 211 and the side wall 212 is a negative current transmission terminal of the cylindrical battery cell 10.

[0309] In some embodiments, please refer to Figures 4, 6, and 21 together, and in conjunction with other figures. Figure 21 is a projected schematic diagram of the current collector 3 and the pressure relief portion 22111 of the cylindrical battery cell 10 provided in Figure 3. Specifically, it is a schematic diagram of the orthographic projection of the pressure relief portion 22111 and the current collector 3 on a projection plane perpendicular to the first direction Z. In Figure 21, the outer contour of the pressure relief portion 22111 is shown as a dashed line. The current collector 3 has a vent hole 301 extending along the first direction Z, and the vent hole 301 is disposed opposite to the pressure relief portion 22111 along the first direction Z. The current collector 3 has a plurality of guide portions 32. The plurality of guide portions 32 are spaced apart around the outer periphery of the vent hole 301.

[0310] The flow collecting component 3 is provided with an exhaust through hole 301 along the first direction Z, which means that the exhaust through hole 301 passes through the flow collecting component 3 along the first direction Z.

[0311] The exhaust port 301 and the pressure relief part 22111 are arranged opposite each other along the first direction Z, meaning that at least a portion of the exhaust port 301 and the pressure relief part 22111 are directly opposite each other along the first direction Z. Based on this, when the pressure value inside the housing 2 reaches a threshold and the pressure relief part 22111 opens to form an exhaust passage, the exhaust port 301 and the exhaust passage can be arranged opposite each other and connected along the first direction Z.

[0312] The guide portion 32 refers to the structure on the collector member 3 that guides the collector member 3 to deform and fold near the exhaust port 301, thereby increasing the size of the exhaust port 301. Specifically, the collector member 3 can be split along the guide portion 32 to expand the exhaust area of ​​the exhaust port 301.

[0313] Multiple guide sections 32 are spaced apart along the circumferential direction E and together surround the outer periphery of the exhaust port 301.

[0314] The first collector component 3a may be provided with the aforementioned exhaust hole 301 and guide portion 32. The second collector component 3b may also be provided with the aforementioned exhaust hole 301 and guide portion 32.

[0315] By adopting the above technical solution, during the thermal runaway of the cylindrical battery cell 10, when the pressure inside the casing 2 reaches a threshold, the pressure relief section 22111 can open under the action of air pressure and form an exhaust channel. The guide section 32 can also deform and flip open towards the pressure relief section 22111 under the action of air pressure, thereby gradually increasing the diameter of the exhaust channel 301. This facilitates the movement of the electrode 11 towards the pressure relief section 22111, allowing it to be released through the exhaust channel 301 and the exhaust passage to the outside of the casing 2. This configuration helps improve the directional pressure relief efficiency of the cylindrical battery cell 10.

[0316] In some embodiments, please refer to Figures 4, 6, and 21 together, and in conjunction with other figures. On a projection plane perpendicular to the first direction Z, the orthographic projection of the exhaust port 301 is located within the orthographic projection of the pressure relief portion 22111.

[0317] In some embodiments, please refer to Figures 4, 6, and 21 together, and in conjunction with other figures. On a projection plane perpendicular to the first direction Z, along the radial direction Y of the electrode assembly 1, the orthographic projection of the end of the guide portion 32 away from the exhaust port 301 is located outside the outer contour of the orthographic projection of the pressure relief portion 22111. Alternatively, in other embodiments, on a projection plane perpendicular to the first direction Z, along the radial direction Y of the electrode assembly 1, the orthographic projection of the end of the guide portion 32 away from the exhaust port 301 coincides with the outer contour of the orthographic projection of the pressure relief portion 22111.

[0318] The pressure relief mechanism 2211 includes a pressure relief portion 22111 and is provided with a first groove 201 as described below, which surrounds the outer periphery of the pressure relief portion 22111. On a projection plane perpendicular to the first direction Z, the outer contour of the orthographic projection of the pressure relief portion 22111 refers to the inner contour of the orthographic projection of the first groove 201, that is, the connection position between the orthographic projection of the pressure relief portion 22111 and the orthographic projection of the first groove 201.

[0319] Understandably, the guide portion 32 extends approximately along the radial direction Y. Specifically, in the radial direction Y, the guide portion 32 extends from the exhaust port 301 in a direction away from the exhaust port 301. In the radial direction Y, the end of the guide portion 32 away from the exhaust port 301 is the first edge 321. As shown in FIG21, on a projection plane perpendicular to the first direction Z, the orthographic projection of the first edge 321 is located outside the outer contour of the orthographic projection of the pressure relief portion 22111; or, on a projection plane perpendicular to the first direction Z, the orthographic projection of the first edge 321 coincides with the outer contour of the orthographic projection of the pressure relief portion 22111.

[0320] By adopting the above technical solution, the guide part 32 can deform and open the current collector 3 towards the pressure relief part 22111 under the action of air pressure, and the diameter of the exhaust hole 301 can be increased to a greater extent. In this way, during the thermal runaway process of the cylindrical battery cell 10, when the electrode 11 is discharged to the outside of the outer casing 2 through the exhaust channel formed by the opening of the pressure relief part 22111, the obstruction effect of the current collector 3 on the electrode 11 can be reduced, which helps to improve the efficiency of the electrode 11 in discharging through the exhaust channel, thereby improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0321] In some embodiments, the guide portion 32 includes a through hole that penetrates the current collecting member 3 along a first direction Z.

[0322] In some embodiments, the guide portion 32 includes a second groove that does not penetrate the current collection member 3 along the first direction Z.

[0323] Understandably, the flow collecting component 3 includes a flow collecting body 31 and the aforementioned guide portion 32. The flow collecting body 31 is provided with an exhaust vent 301, and a plurality of guide portions 32 are spaced apart along the circumferential direction E on the flow collecting body 31.

[0324] The current collector 31 can be welded to the first electrode winding portion 1121 of the electrode 112 to form the second welding portion 6.

[0325] The current collector 31 can be welded to the electrode terminal 5 to form the first welded part 4.

[0326] Specifically, the main body 31 and the guide portion 32 form a second groove, so that the guide portion 32 is a relatively weak part of the collecting member 3, and the structural strength of the guide portion 32 is lower than that of other parts of the collecting member 3. The guide portion 32 may have a groove formed by a notch, which is the second groove.

[0327] By adopting the above technical solution, the guide part 32 can guide the part of the current collector 3 near the exhaust hole 301 to deform and open toward the pressure relief part 22111 during thermal runaway, thereby improving the directional pressure relief effect of the cylindrical battery cell 10.

[0328] In some embodiments, please refer to Figures 4, 6, and 21 together, and in conjunction with other figures. The guide portion 32 extends to the vent hole 301. It will be understood that the guide portion 32 and the wall of the vent hole 301 are connected.

[0329] In other embodiments, the guide portion 32 is spaced apart from the wall of the exhaust hole 301, and the minimum distance between the guide portion 32 and the wall of the exhaust hole 301 is ≤10mm.

[0330] The minimum distance between the guide part 32 and the wall of the exhaust hole 301 can be 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.

[0331] This configuration allows the guide section 32 to guide the portion of the flow collector 3 near the exhaust port 301 to deform and open toward the pressure relief section 22111 during pressure relief, thereby increasing the exhaust port 301 and achieving a highly efficient directional pressure relief effect.

[0332] In some embodiments, please refer to Figures 4, 6, and 21 together, and in conjunction with other figures. The electrode assembly 1 has a central hole 101 extending along a first direction Z, and a first electrode lug 1121 is disposed around the outer periphery of the central hole 101. On a projection plane perpendicular to the first direction Z, the orthographic projection of the central hole 101 lies within the orthographic projection of the pressure relief portion 22111. The central hole 101 and the exhaust port 301 are opposite to and communicate with each other along the first direction Z.

[0333] With this configuration, when the pressure inside the outer casing 2 reaches the threshold and at least part of the pressure relief section 22111 opens to form an exhaust channel, the central hole 101, the exhaust through hole 301, and the exhaust channel are connected sequentially along the first direction Z. This facilitates exhaust and helps improve the directional pressure relief efficiency.

[0334] In some embodiments, please refer to Figures 4, 6, and 21 together, and in conjunction with other figures. On a projection plane perpendicular to the first direction Z, the orthographic projection of the exhaust port 301 and the orthographic projection of the center hole 101 are both located within the orthographic projection of the pressure relief portion 22111.

[0335] In some embodiments, please refer to Figures 4, 6, and 7 together, and in conjunction with other figures. On a projection plane perpendicular to the first direction Z, a portion of the orthographic projection of the second pole lug winding portion 1122 lies within the orthographic projection of the pressure relief portion 22111.

[0336] It should be noted that, on the projection plane perpendicular to the first direction Z, the orthographic projection of the second electrode ear winding portion 1122 refers to the orthographic projection of the root position of the second electrode ear winding portion 1122. The root position of the second electrode ear winding portion 1122 refers to the end region of the second electrode ear winding portion 1122 along the first direction Z near the electrode body 111. For example, the root position of the second electrode ear winding portion 1122 can be the transition connection portion 11222 described below.

[0337] As an example, on a projection plane perpendicular to the first direction Z, a portion of the orthographic projection of the transition connection portion 11222 of the second pole ear winding portion 1122 lies within the orthographic projection of the pressure relief portion 22111.

[0338] Based on this, on the projection plane perpendicular to the first direction Z, a portion of the orthographic projection of the second electrode winding portion 115 is located within the orthographic projection of the pressure relief portion 22111. Specifically, on the projection plane perpendicular to the first direction Z, the orthographic projection of the second electrode winding portion 115 is the orthographic projection of the electrode body 111 of the second electrode winding portion 115, which is also the orthographic projection of the second body winding portion 1113.

[0339] By adopting the above technical solution, both the second electrode winding portion 115 and the first electrode winding portion 114 are aligned with the pressure relief portion 22111 along the first direction Z. During the pressure relief process caused by thermal runaway of the cylindrical battery cell 10, when the pressure value inside the casing 2 reaches a threshold, the first electrode winding portion 114 and at least a portion of the second electrode winding portion 115 surrounding the first electrode winding portion 114 can loosen under the action of air pressure and be released outside the casing 2 through the exhaust channel. Furthermore, the high-temperature and high-pressure medium generated inside the cylindrical battery cell 10 can also be released along with the electrode 11. Thus, the cylindrical battery cell 10 can achieve a highly efficient directional pressure relief effect.

[0340] In some embodiments, please refer to Figures 4 to 15 together with other figures. Figure 14 is an enlarged view of point F in Figure 8. In Figure 14, the transition connection 11222 and the segment 11221 are divided by dashed lines. Figure 15 is an enlarged view of point G in Figure 7. The second electrode ear winding portion 1122 includes a plurality of segments 11221 distributed along the winding direction W of the electrode assembly 1, the segments 11221 being bent. Along the winding direction W of the electrode assembly 1, a cutting groove 102 is provided between any two adjacent segments 11221. On a projection plane perpendicular to the first direction Z, the orthographic projection of the first groove bottom surface 103 of at least one cutting groove 102 lies within the orthographic projection of the pressure relief portion 22111.

[0341] It should be further noted that, in the first direction Z, the segment 11221 of the second electrode ear winding portion 1122 extends beyond the first electrode ear winding portion 1121. The current collector 3 is welded to the second electrode ear winding portion 1122, specifically to the segment 11221 of the second electrode ear winding portion 1122.

[0342] The cut-off groove 102 is a groove structure formed between any two adjacent segments 11221 along the winding direction W of the electrode assembly 1. The cut-off groove 102 penetrates the end face of the tab 112 away from the electrode body 111, and the cut-off groove 102 does not penetrate the tab 112 along the winding direction W of the electrode assembly 1.

[0343] It should be noted that when the electrode 11 is in a wound state to form a wound structure, the multiple segments 11221 of the second electrode tab winding portion 1122 are sequentially distributed along the winding direction W of the electrode assembly 1, and the segments 11221 and the cutting grooves 102 are alternately arranged along the winding direction W of the electrode assembly 1. When the electrode 11 is in an unfolded state, as shown in FIG8, the multiple segments 11221 of the electrode tab 112 are sequentially distributed along the length direction X of the electrode 11, that is, sequentially distributed along the length direction X of the electrode tab 112, and the segments 11221 and the cutting grooves 102 are alternately distributed along the length direction X of the electrode 11.

[0344] The section 11221 is bent, either towards the winding axis L or away from it. Based on this, the end region of the second electrode winding portion 1122 of the electrode tab 112 away from the electrode body 111 along the first direction Z can be bent, thereby gathering and assembling to form a relatively dense stacked layer. Specifically, the section 11221 of the second electrode winding portion 1122 is bent along the first direction Z away from the electrode body 111 to form a stacked layer.

[0345] The first groove bottom surface 103 refers to the bottom wall of the cut-off groove 102 along the first direction Z, specifically the wall surface of the cut-off groove 102 along the first direction Z near the electrode body 111. Each cut-off groove 102 is provided with a first groove bottom surface 103.

[0346] In some possible designs, as shown in Figures 8, 9 and 14, the second electrode ear winding portion 1122 also includes a transition connection portion 11222 as described below. The transition connection portion 11222 is disposed between the cut-off piece 11221 and the electrode body 111 along the first direction Z. The transition connection portion 11222 is connected to the first electrode ear winding portion 1121, and the first groove bottom surface 103 of the cut-off groove 102 is formed on the side edge of the transition connection portion 11222 away from the electrode body 111 along the first direction Z. Alternatively, in some other possible designs, the second electrode loop winding portion 1122 does not include the transition connection portion 11222 described below. The slit 11221 contacts the electrode body 111 along the first direction Z. The first groove bottom surface 103 of the cutting groove 102 is formed on the side edge of the electrode body 111 along the first direction Z near the slit 11221, such that the side edge of the slit 11221 along the first direction Z near the electrode body 111 is the boundary between the electrode body 111 and the second electrode loop winding portion 1122.

[0347] On a projection plane perpendicular to the first direction Z, the orthographic projection of the bottom surface 103 of at least one cut-off groove 102 lies within the orthographic projection of the pressure relief section 22111. This means that the orthographic projection of the bottom surface 103 of at least one first groove lies within the orthographic projection of the pressure relief section 22111, and also that the area enclosed by the outer contour of the orthographic projection of the bottom surface 103 of at least one first groove lies within the area enclosed by the outer contour of the orthographic projection of the pressure relief section 22111. When there is only one cut-off groove 102, on a projection plane perpendicular to the first direction Z, the orthographic projection of the bottom surface 103 of the first groove lies within the orthographic projection of the pressure relief section 22111. When there are multiple cut-off grooves 102, on the projection plane perpendicular to the first direction Z, the orthographic projections of the first groove bottom surfaces 103 of all cut-off grooves 102 are located within the orthographic projection of the pressure relief portion 22111; or, on the projection plane perpendicular to the first direction Z, the orthographic projections of the first groove bottom surfaces 103 of some cut-off grooves 102 are all located within the orthographic projection of the pressure relief portion 22111, and the orthographic projections of at least a portion of the first groove bottom surfaces 103 of some cut-off grooves 102 are all located outside the orthographic projection of the pressure relief portion 22111. Based on this, as shown in Figures 7 and 15, on the projection plane perpendicular to the first direction Z, at least a portion of the orthographic projection of the cut-off grooves 102 formed in the second electrode ear winding portion 1122 is located within the orthographic projection of the pressure relief portion 22111.

[0348] The second electrode lug winding portion 1122 includes a plurality of bent segments 11221 distributed along the winding direction W of the electrode assembly 1. A cut-off groove 102 is provided between any two adjacent segments 11221 along the winding direction W of the electrode assembly 1, thereby reducing the density of the deposited layer formed by the portion of the second electrode lug winding portion 1122 with the cut-off groove 102. By placing the orthographic projection of the first groove bottom surface 103 of at least one cut-off groove 102 within the orthographic projection of the pressure relief portion 22111 on a projection plane perpendicular to the first direction Z, the self-binding effect of the second electrode lug winding portion 1122 on the portion of the pressure relief portion 22111 is weakened under the action of the cut-off groove 102. This also weakens the mutual binding effect of the electrode 11 surrounding the outer periphery of the first electrode winding portion 114 and on the portion of the pressure relief portion 22111. During the thermal runaway of the cylindrical battery cell 10, the binding effect of the second electrode winding portion 1122 on at least a portion of the pressure relief portion 22111 and the binding effect of the first electrode winding portion 1121 are easily broken under the action of air pressure. This allows not only the first electrode winding portion 114 to easily release pressure through the exhaust channel to the outside of the casing 2, but also the portion of the electrode 11 surrounding the first electrode winding portion 114 and directly opposite the pressure relief portion 22111 to easily release pressure through the exhaust channel to the outside of the casing 2. This helps the cylindrical battery cell 10 achieve a highly efficient directional pressure relief effect, improving the problem of low directional pressure relief efficiency and thus contributing to improved reliability.

[0349] It should also be noted that by forming a cut-off groove 102 in the second electrode winding portion 1122, the connection strength between the electrode layers of the second electrode winding portion 1122 and the structural strength of the electrode 112 can be reduced. This facilitates the breaking of at least part of the binding effect of the second electrode winding portion 1122 on the pressure relief portion 22111 under the action of air pressure, so that the electrode 11 can be released to the outside of the outer casing 2 through the exhaust channel formed by the opening of the pressure relief portion 22111, thereby improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0350] It should also be noted that the truncated section 11221 is bent so that the end region of the second electrode loop winding portion 1122 opposite to the electrode body 111 along the first direction Z can be bent to gather and form a relatively dense stacked layer. The cutting groove 102 formed in the second electrode loop winding portion 1122 reduces the density of the stacked layer. This reduces the self-binding effect of the second electrode loop winding portion 1122. Furthermore, the cutting groove 102 in the second electrode loop winding portion 1122 can form a channel for venting, facilitating the discharge of high-temperature and high-pressure media and improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0351] It should be further noted that the positive electrode tab 112a may include a plurality of segments 11221 distributed along the winding direction W, and in the positive electrode tab 112a, a cutting groove 102 is provided between any two adjacent segments 11221 along the winding direction W. In the positive electrode tab 112a, the orthographic projection of the bottom surface 103 of at least one cutting groove 102 is located within the orthographic projection of the pressure relief section 22111.

[0352] The negative electrode tab 112b includes a plurality of segments 11221 distributed along the winding direction W, and a cutting groove 102 is provided between any two adjacent segments 11221 along the winding direction W in the negative electrode tab 112b. In the negative electrode tab 112b, the orthographic projection of the bottom surface 103 of the first groove of at least one cutting groove 102 is located within the orthographic projection of the pressure relief section 22111.

[0353] In some embodiments, please refer to FIG13 and other figures. The electrode assembly 1 has a winding axis L parallel to the first direction Z, and at least one segment 11221 has a bent section 112211 at one end in the first direction Z.

[0354] The bent section 112211 is the portion of the second electrode ear winding portion 1122 that is bent relative to the electrode body 111. Specifically, the bent section 112211 is formed at the end of the second electrode ear winding portion 1122 that is away from the electrode body 111 along the first direction Z.

[0355] In some possible designs, as shown in Figure 13 and in conjunction with other figures, the bent segment 112211 includes a first bent portion 1122111, which is bent relative to the electrode body 111 in a direction close to the winding axis L.

[0356] The first bending portion 1122111 refers to the part of the bending section 112211 that is bent relative to the electrode body 111 toward the winding axis L.

[0357] In some possible designs, as shown in Figure 13 and in conjunction with other figures, the bent segment 112211 includes a second bent portion 1122112, which is bent relative to the electrode body 111 in a direction away from the winding axis L.

[0358] The second bending section 1122112 refers to the part of the bending section 112211 that is bent away from the winding axis L relative to the electrode body 111.

[0359] This configuration allows the end region of the second electrode loop winding portion 1122 11221 facing away from the electrode body 111 along the first direction Z to be bent, thereby gathering and assembling together to form a relatively dense stacked layer. This facilitates the welding of the second electrode loop winding portion 1122 11221 to the current collector 3 described below. Furthermore, it provides a stronger binding effect on the electrode 11, resulting in higher charge / discharge performance for the electrode assembly 1.

[0360] In some embodiments, please refer to FIG13, and in conjunction with other figures. Each segment 11221 has a bent segment 112211 at one end in the first direction Z.

[0361] Each segment 11221 may include a first bending portion 1122111 but not a second bending portion 1122112, allowing all segments 11221 to be bent towards the winding axis L, thus enabling a regular bending operation of the second electrode ear winding portion 1122. Alternatively, each segment 11221 may include a second bending portion 1122112 but not a first bending portion 1122111, allowing the second electrode ear winding portion 1122 to be bent. Alternatively, each segment 11221 may include a first bending portion 1122111 and a second bending portion 1122112, allowing the second electrode ear winding portion 1122 to be bent. Alternatively, among the multiple segments 11221, a portion of the segment 11221 has a bent segment 112211 including a first bent portion 1122111 or a second bent portion 1122112, and another portion of the segment 11221 has a bent segment 112211 including a first bent portion 1122111 and a second bent portion 1122112. Alternatively, among the multiple segments 11221, a portion of the segment 11221 has a bent segment 112211 including a first bent portion 1122111, another portion of the segment 11221 has a bent segment 112211 including a second bent portion 1122112, and the remaining portion of the segment 11221 has a bent segment 112211 including a first bent portion 1122111 and a second bent portion 1122112.

[0362] This configuration allows each segment 11221 of the second electrode ear winding portion 1122 to be bent, so that the end region of the second electrode ear winding portion 1122 away from the electrode body 111 along the first direction Z can be bent, thereby gathering and assembling to form a relatively dense stacked layer.

[0363] In some embodiments, as shown in FIG13 and in conjunction with other figures, the first bending portion 1122111 is provided to bend radially Y along the electrode assembly 1.

[0364] Specifically, in the radial direction Y of the electrode assembly 1, the first bending portion 1122111 is bent toward the direction close to the winding axis L.

[0365] In some embodiments, as shown in FIG13 and in conjunction with other figures, the second bending portion 1122112 is provided to bend radially Y along the electrode assembly 1.

[0366] Specifically, in the radial direction Y of the electrode assembly 1, the second bending portion 1122112 is bent in a direction away from the winding axis L.

[0367] By adopting the above technical solution, the bending section 112211 is bent radially Y, which enables the second pole ear winding portion 1122 to achieve bending treatment in a better way to form a stacked layer.

[0368] In some other embodiments, the first bending portion 1122111 may be bent in a direction intersecting the radial Y, and the second bending portion 1122112 may also be bent in a direction intersecting the radial Y.

[0369] In some embodiments, as shown in FIG13 and in conjunction with other figures, the bending segment 112211 includes at least one first bending portion 1122111 and at least one second bending portion 1122112, the first bending portion 1122111 and the second bending portion 1122112 being alternately arranged along a first direction Z.

[0370] This configuration allows the end region of the second electrode ear winding portion 1122 that is away from the electrode body 111 along the first direction Z to be bent, thereby gathering and assembling to form a relatively dense stacked layer.

[0371] In some embodiments, please refer to FIG11 and other accompanying drawings. In FIG11, the transition connection portion 11222 and the segment 11221 are divided by dashed lines. Both electrodes 11 include an electrode body 111 and a tab 112. The two electrodes 11 include a positive electrode 11a and a negative electrode 11b. The tab 112 of the positive electrode 11a may not be coated with an active material layer 1111. The tab 112 of the negative electrode 11b may also not be coated with an active material layer 1111. In the first direction Z, the positive electrode 11a and the tab 112 are provided with an insulating layer 113 at the end region near the electrode body 111, and the segment 11221 is located on the side of the insulating layer 113 facing away from the electrode body 111.

[0372] Understandably, in both the positive electrode 11a and the negative electrode 11b, the tab 112 includes a first tab winding portion 1121 and a second tab winding portion 1122. The second tab winding portion 1122 includes multiple segments 11221 and is provided with multiple cutting grooves 102. In both the positive and negative electrode 11a and 11b, in the first direction Z, the segments 11221 of the second tab winding portion 1122 extend beyond the first tab winding portion 1121. On a projection plane perpendicular to the first direction Z, the orthographic projections of the first tab winding portion 1121 of the positive electrode 11a and the negative electrode 11b, and the first groove bottom surface 103 of at least one cutting groove 102, are all located within the orthographic projection of the pressure relief portion 22111.

[0373] Among them, the insulating layer 113 refers to a structural layer with insulating properties, and the insulating layer 113 can be an insulating coating, insulating adhesive, etc.

[0374] As shown in Figure 11, the insulating layer 113 can be disposed only in the end region of the tab 112 near the electrode body 111, and not on the first electrode body 111a. Therefore, the edge of the insulating layer 113 along the first direction Z near the first electrode body 111a forms the boundary between the positive electrode tab 112a and the first electrode body 111a. Alternatively, the insulating layer 113 can be disposed in the end region of the first electrode body 111a along the first direction Z near the positive electrode tab 112a, and in the end region of the tab 112 near the electrode body 111. When the end region of the first electrode body 111a near the positive electrode tab 112a is not coated with the active material layer 1111, the portion of the first electrode body 111a without the active material layer 1111 must be provided with the insulating layer 113.

[0375] In the first direction Z, at least a portion of the insulating layer 113 is disposed on the end region of the second electrode lug winding portion 1122 near the electrode body 111, and on the end region of the first electrode lug winding portion 1121 near the electrode body 111. The first electrode lug winding portion 1121 may be entirely provided with the insulating layer 113; alternatively, the end region of the first electrode lug winding portion 1121 away from the electrode body 111 in the first direction Z may not have the insulating layer 113.

[0376] In some possible designs, as shown in Figure 11, in the first direction Z, the segments 11221 of the positive electrode tab 112a are spaced apart on the side of the insulating layer 113 facing away from the first electrode body 111a. Based on this, the first groove bottom surface 103 of the cut-off groove 102 is spaced apart on the side of the insulating layer 113 facing away from the first electrode body 111a along the first direction Z. Alternatively, in other possible designs, in the first direction Z, the segments 11221 of the positive electrode tab 112a are located on the side of the insulating layer 113 facing away from the first electrode body 111a. Furthermore, the first groove bottom surface 103 of the cut-off groove 102 coincides with the edge of the insulating layer 113 facing away from the first electrode body 111a along the first direction Z.

[0377] This configuration provides an insulating layer 113 on the positive electrode 11a, which effectively improves the short circuit problem between the positive electrode 11a and the negative electrode 11b.

[0378] In some embodiments, please refer to Figures 8, 9, 11, 14, and 16 together with other figures. Figure 16 is an enlarged view of section H in Figure 8. In Figures 12 and 16, the segment 11221 and the transition connection portion 11222 are divided by dashed lines. The second electrode lug winding portion 1122 also includes the transition connection portion 11222. The electrode body 111, the transition connection portion 11222, and the segment 11221 are arranged sequentially along the first direction Z. The transition connection portion 11222 is connected to the first electrode lug winding portion 1121. The transition connection portion 11222 and any two segments 11221 adjacent to each other along the winding direction W of the electrode assembly 1 form a cut-off groove 102, and the first groove bottom surface 103 of the cut-off groove 102 is formed on one edge of the transition connection portion 11222 used to connect the segment 11221.

[0379] Understandably, the second electrode winding portion 1122 includes a transition connection portion 11222 and a plurality of segments 11221, which are spaced apart along the winding direction W on the transition connection portion 11222. The electrode body 111 is connected to one side of the transition connection portion 11222 along the first direction Z, and the segments 11221 are connected to the other side of the transition connection portion 11222 along the first direction Z. Specifically, the current collector is connected to the side of the transition connection portion 11222 away from the segments 11221 along the first direction Z.

[0380] Understandably, the bottom surface 103 of the first groove is formed on one side edge of the transition connection 11222 along the first direction Z, close to the section 11221.

[0381] The transition connection portion 11222 is connected to the first electrode ear winding portion 1121. Specifically, the transition connection portion 11222 and the first electrode ear winding portion 1121 are distributed and connected sequentially along the winding direction W.

[0382] A transition connection portion 11222 connects the electrode body 111 and the cut-off piece 11221. On one hand, this allows the electrode body 111 and the cut-off piece 11221 to be spaced apart along the first direction Z, and the electrode body 111 and the cutting groove 102 to be spaced apart along the first direction Z. This facilitates avoiding the electrode body 111 during the cutting of the tab 112 to form the cutting groove 102 and the cut-off piece 11221, thus preventing the electrode body 111 from being cut to a certain extent. Furthermore, it solves the problem that the electrode body 111 is easily torn because the first groove bottom surface 103 of the cutting groove 102 is formed on one side edge of the electrode body 111. On the other hand, the transition connection portion 11222 can block the cut-off piece 11221, thus isolating the cut-off piece 11221 from the main body P of the electrode assembly 1. This improves the problem of short circuits in the electrode assembly 1 caused by the cut-off piece 11221 being bent and inserted into the main body P, reducing the risk of short circuits.

[0383] It should be noted that, referring to Figure 11 and other accompanying figures, in the positive electrode 11a, an insulating layer 113 is disposed on at least a portion of the transition connection 11222. In some possible designs, as shown in Figure 11, the insulating layer 113 is disposed on a portion of the transition connection 11222 such that the insulating layer 113 and the segment 11221 are spaced apart along the first direction Z. Alternatively, in other possible designs, the insulating layer 113 completely covers the transition connection 11222, such that the edge of the insulating layer 113 facing away from the electrode body 111 along the first direction Z overlaps with the edge of the segment 11221 approaching the transition connection 11222 along the first direction Z.

[0384] In some embodiments, please refer to Figures 8, 9, 14, and 16 together with other figures. The dimension of one side edge of each piece 11221 used to connect the transition connection portion 11222 in the winding direction W of the electrode assembly 1 is H1, and the dimensions of the transition connection portion 11222 and the piece 11221 in the first direction Z are H2, where 0.01≤H2 / H1≤0.3.

[0385] The section 11221, used to connect one side edge of the transition connection portion 11222, refers to the side edge of the section 11221 along the first direction Z that is close to the electrode body 111, i.e., the edge of the section 11221 at the boundary between the section 11221 and the transition connection portion 11222. The boundary between the section 11221 and the transition connection portion 11222 is mainly based on the position of the bottom surface 103 of the first groove, which can be specifically referred to in Figures 9, 14, and 16 as the dashed lines used to divide the transition connection portion 11222 and the section 11221. Understandably, the side edge of the section 11221 used to connect the transition connection portion 11222 is collinearly connected to the bottom surface 103 of the first groove.

[0386] The dimension of the side edge of the piece 11221 used to connect the transition connection portion 11222 in the winding direction W of the electrode assembly 1 refers to the maximum dimension of the piece 11221 in the winding direction W. It also refers to the dimension of the side edge of the piece 11221 used to connect the transition connection portion 11222 in the length direction X of the electrode 11 when the electrode 11 is in the unfolded state. In other words, the maximum dimension of the piece 11221 in the length direction X of the electrode 11 when the electrode 11 is in the unfolded state.

[0387] The sum of the dimensions of the transition connection 11222 and the segment 11221 in the first direction Z refers to the sum of the dimensions of the transition connection 11222 and the segment 11221 in the first direction Z before the segment 11221 is bent or when the segment 11221 is in the unfolded state, which is the maximum dimension of the tab 112 in the first direction Z.

[0388] 0.01≤H2 / H1≤0.3, where H2 / H1 can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, etc.

[0389] This configuration allows the cut piece 11221 to have a larger size in the winding direction W, which facilitates the winding of the cut piece 11221 and, to a certain extent, ensures the structural integrity of the electrode assembly 1 and, to a certain extent, the charging and discharging performance of the cylindrical battery cell 10.

[0390] In some embodiments, please refer to Figures 8, 9, 14, and 16 together with other figures. The dimension of the transition connection 11222 in the first direction Z is H3, where 0.1mm ≤ H3 ≤ 2mm.

[0391] The dimension of the transition connection portion 11222 in the first direction Z refers to the distance between the edge of the piece 11221 near the electrode body 111 and the edge of the electrode body 111 near the piece 11221 in the first direction Z.

[0392] H3 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 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, etc.

[0393] With this configuration, the transition connection portion 11222 has a suitable width in the first direction Z to block the cut-off piece 11221, based on the fact that the tab 112 can form the cut-off groove 102, thus improving the problem of the cut-off piece 11221 bending and inserting into the main body portion P.

[0394] In some embodiments, please refer to Figures 3, 4, 6, 7, and 15 together, and in conjunction with other figures. The housing 2 also includes a first end wall 221, which is disposed opposite to the electrode assembly 1 along a first direction Z. The first end wall 221 has a first groove 201 and the aforementioned pressure relief portion 22111, the pressure relief portion 22111 being located within the area enclosed by the first groove 201. A weak portion 22112 is provided at the bottom of the first groove 201, and the pressure relief portion 22111 is connected to the weak portion 22112. At least a portion of the weak portion 22112 is configured to disconnect during pressure relief to open the pressure relief portion 22111.

[0395] Understandably, the first end wall 221 includes a first wall 2212, a pressure relief portion 22111, and a weak portion 22112, which together constitute a pressure relief mechanism 2211. Specifically, the weak portion 22112 surrounds the outer periphery of the pressure relief portion 22111, the first wall 2212 surrounds the outer periphery of the pressure relief portion 22111, and the weak portion 22112 connects the pressure relief portion 22111 and the first wall 2212. The weak portion 22112, the pressure relief portion 22111, and the first wall 2212 are integrally formed and enclose the aforementioned first groove 201. Based on this, the first groove 201 makes the thickness of the weak portion 22112 less than the thickness of the first wall 2212, thereby making the structural strength of the weak portion 22112 lower than that of the first wall 2212. Understandably, the first end wall 221 of the outer casing 2 has an integrally formed weak portion 22112 and pressure relief portion 22111 of the pressure relief mechanism 2211.

[0396] The weak point 22112 refers to the part of the outer shell 2 with relatively weak structural strength, which is a part of the pressure relief mechanism 2211. The structural strength of the weak point 22112 is lower than that of other parts of the outer shell 2. As an example, as shown in Figure 6, a groove can be provided on the first end wall 221, forming a first groove 201. This groove is specifically located between the pressure relief part 22111 and the first wall 2212, for example, a groove can be provided on the end cap 22 of the outer shell 2.

[0397] The pressure relief section 22111 refers to the part on the outer casing 2 that can be opened to form an exhaust passage, and is a part of the pressure relief mechanism 2211. Specifically, when the pressure value inside the outer casing 2 reaches a threshold, at least a portion of the weak section 22112 will break under the action of air pressure to disconnect the connection between the pressure relief section 22111 and the first wall 2212, thereby causing at least a portion of the pressure relief section 22111 to open and form an exhaust passage.

[0398] By adopting the above technical solution, the pressure relief section 22111 can be opened to form an exhaust channel when the pressure value inside the cylindrical battery cell 10 reaches the threshold, thereby facilitating the discharge of the electrode 11 to the outside of the outer casing 2 through the exhaust channel formed by at least the partial opening of the pressure relief section 22111 during thermal runaway.

[0399] In other embodiments, the housing further includes a first wall 2212 and a pressure relief mechanism 2211, the first wall 2212 and the electrode assembly 1 being disposed opposite each other along a first direction Z. The first wall 2212 is fixedly connected to the pressure relief mechanism 2211, the pressure relief mechanism 2211 having a first groove 201 and a pressure relief portion 22111, the pressure relief portion 22111 being located within the area enclosed by the first groove 201. A weak portion 22112 is provided at the bottom of the first groove 201, and the pressure relief portion 22111 is connected to the weak portion 22112. At least a portion of the weak portion 22112 is configured to be disconnectable during pressure relief to open the pressure relief portion 22111.

[0400] Understandably, the pressure relief mechanism 2211 includes a pressure relief portion 22111 and a weak portion 22112. Specifically, the weak portion 22112 surrounds the outer periphery of the pressure relief portion 22111, the first wall 2212 surrounds the outer periphery of the pressure relief portion 22111, the weak portion 22112 is connected to the outer periphery of the pressure relief portion 22111, and the weak portion 22112 and the pressure relief portion 22111 together form the aforementioned first groove 201. Based on this, the provision of the first groove 201 makes the thickness of the weak portion 22112 less than the thickness of other parts of the pressure relief mechanism 22111, thereby making the structural strength of the weak portion 22112 lower than that of other parts of the pressure relief mechanism 22111.

[0401] The pressure relief mechanism 2211 is fixedly connected to the first wall 2212. This connection can be made by the weakest part 22112 of the pressure relief mechanism 2211 to the first wall 2212, or by other parts of the pressure relief mechanism 2211 to the first wall 2212.

[0402] The pressure relief mechanism 2211 can be fixedly connected to the first wall 2212 by welding or other means, so that the pressure relief mechanism 2211 and the first wall 2212 are separately set.

[0403] The pressure relief mechanism 2211 and the first wall 2212 can constitute the aforementioned first end wall 221.

[0404] The weak point 22112 refers to the part of the pressure relief mechanism 2211 where the structural strength is relatively weak, and is a part of the pressure relief mechanism 2211. Specifically, the structural strength of the weak point 22112 is lower than that of other parts of the pressure relief mechanism 2211. As an example, the pressure relief mechanism 2211 may have a groove formed by the groove, which is a first groove 201, specifically surrounding the outer periphery of the pressure relief part 22111.

[0405] When the pressure inside the outer casing 2 reaches the threshold, the weak part 22112 will break under the action of air pressure, thereby breaking the connection between the pressure relief part 22111 and the first wall 2212, so that the pressure relief part 22111 opens to form an exhaust channel.

[0406] By adopting the above technical solution, the pressure relief section 22111 can be opened to form an exhaust channel when the pressure value inside the cylindrical battery cell 10 reaches the threshold, thereby facilitating the electrode 11 to be released to the outside of the outer casing 2 through the exhaust channel formed by the pressure relief section 22111 under the action of air pressure.

[0407] When the aforementioned weak part 22112 is directly connected to the first wall 2212, on the projection plane perpendicular to the first direction Z, the outer contour of the orthographic projection of the pressure relief mechanism 2211 is the outer contour of the orthographic projection of the first groove 201, which is also the outer contour of the orthographic projection of the weak part 22112.

[0408] In some embodiments, please refer to Figures 4, 6, 7, and 15 together, and in conjunction with other figures. On a projection plane perpendicular to the first direction Z, the outer contour of the orthographic projection of the pressure relief portion 22111 is circular.

[0409] This configuration ensures that the exhaust channel formed by the pressure relief section 22111 is roughly circular, while the electrode assembly 1 is roughly cylindrical. This facilitates the release of pressure through the exhaust channel when the electrode 11 experiences thermal runaway, thereby helping to improve the directional pressure relief effect of the cylindrical battery cell 10.

[0410] In some embodiments, please refer to Figures 4, 10, and 17 together, and in conjunction with other figures. On a projection plane perpendicular to the first direction Z, the two ends of the orthographic projection of the first welding portion 4 have a first projection endpoint M1 and a second projection endpoint M2, respectively. The first projection endpoint M1 is closer to the first electrode lug winding portion 1121 than the second projection endpoint M2. The area between the first arc line M3, which passes through the first projection endpoint M1 and surrounds the first electrode lug winding portion 1121, and the second arc line M4, which passes through the second projection endpoint M2 and surrounds the first electrode lug winding portion 1121, is the first transverse region M5. At least some of the cut-off grooves 102 form a first group of grooves. In the first group of grooves, the orthographic projection of the first groove bottom surface 103 of all the cut-off grooves 102 is located within the first transverse region M5.

[0411] Understandably, on the projection plane perpendicular to the first direction Z, the first projection endpoint M1 and the second projection endpoint M2 are respectively located at the two ends of the radial Y of the orthographic projection of the first welding part 4. The first arc M3 passes through the first projection endpoint M1, and the second arc M4 passes through the second projection endpoint M2. Both the first arc M3 and the second arc M4 are arranged around the outer periphery of the coiling axis L. The first arc M3 and the second arc M4 are spaced apart along the radial Y, and the second arc M4 surrounds the outer periphery of the first arc M3, so that the first arc M3 and the second arc M4 alternately form a first transverse region M5, which is approximately annular. The first arc M3 and the second arc M4 are both arranged around the outer periphery of the central hole 101.

[0412] When there are multiple first welding parts 4, on the projection plane perpendicular to the first direction Z, each of the multiple first welding parts 4 has a first projection endpoint M1 and a second projection endpoint M2, and the first arc M3 passes through multiple first projection endpoints M1, and the second arc M4 passes through multiple second projection endpoints M2.

[0413] In this design, both the first arc M3 and the second arc M4 are arc-shaped. As an example, as shown in Figure 17, both the first arc M3 and the second arc M4 are circular.

[0414] In the first group of slots, the orthographic projection of the bottom surface 103 of the first slot of all cut-off slots 102 is located within the first transverse region M5. This means that on the projection plane perpendicular to the first direction Z, the orthographic projection of the bottom surface 103 of the first slot of each cut-off slot 102 in the first group of slots is substantially located within the first transverse region M5. Specifically, all cut-off slots 102 whose orthographic projections of the bottom surface 103 of the first slot are substantially located within the first transverse region M5 on the projection plane perpendicular to the first direction Z constitute the first group of slots. It can be understood that the portion of the second electrode ear winding portion 1122 where the first welding portion 4 is formed has the aforementioned cut-off slot 102.

[0415] It should be further explained that, on the projection plane perpendicular to the first direction Z, when the orthographic projection of a portion of the first groove bottom surface 103 of a certain cut-off groove 102 is located within the first transverse region M5, the first groove bottom surface 103 of the cut-off groove 102 can be defined as being basically located within the first transverse region M5, and the cut-off groove 102 is defined as one of the cut-off grooves 102 in the first group of grooves.

[0416] In some possible designs, please refer to Figures 4, 7, 15, and 17, as well as other accompanying drawings. In the first group of slots, the number of turns of a single cut-off slot 102 is ≤3.

[0417] The number of turns of a single cut-off groove 102 refers to the number of turns of the first groove bottom surface 103 of a single cut-off groove 102.

[0418] The number of turns of a single cut-off groove 102 can be 1 turn, 2 turns, 3 turns, or less than 1 turn, more than 1 turn and less than 2 turns, more than 2 turns and less than 3 turns, etc.

[0419] As an example, as shown in Figure 15, the cut-off groove 102 shown in Figure 15 has less than one turn.

[0420] In some possible designs, please refer to Figures 4, 7, 15, and 17 together with other accompanying drawings. In the first set of slots, the number of cut-off slots 102 that are radially opposite and interconnected along the Y direction of the electrode assembly 1 is ≤3.

[0421] Understandably, on the projection plane perpendicular to the first direction Z, the number of consecutive, opposite, and connected cutoff slots 102 along the radial direction Y is ≤3. On the projection plane perpendicular to the first direction Z, the number of consecutive, opposite, and connected cutoff slots 102 along the radial direction Y can be 3 or 2; or, any two cutoff slots 102 are not opposite and connected along the radial direction Y.

[0422] As an example, as shown in Figure 15, the number of radially opposite and connected cut-off slots 102 can be two.

[0423] By adopting the above technical solution, based on the cutting groove 102 provided in the part of the second electrode ear winding portion 1122 where the first welding portion 4 is formed, the stacked layer formed by bending in the part of the second electrode ear winding portion 1122 where the first welding portion 4 is formed will not be too thin due to the setting of the cutting groove 102. Thus, the part of the second electrode ear winding portion 1122 where the first welding portion 4 is formed can bear the welding penetration of the current collector 3 and the electrode terminal 5, which can improve the problem of laser penetrating the electrode ear 112 and burning the diaphragm 12 during the welding process of the current collector 3 and the electrode terminal 5. This can improve the problem of short circuit of the electrode assembly 1 caused by the welding of the current collector 3 and the electrode terminal 5 and reduce the risk of short circuit.

[0424] In some embodiments, please refer to Figures 4, 6, 10, 18, and 19 together with other accompanying drawings. Figure 18 is a projected schematic diagram of the electrode assembly 1 and current collector 3 of a cylindrical battery cell 10 according to some embodiments of this application. Specifically, it is a schematic diagram of the orthographic projection of the electrode assembly 1 and the current collector 3 on a projection plane perpendicular to the first direction Z. In Figure 18, the area shown by the cross-sectional line is the first transverse region M5, and the first arc M3 and the second arc M4 are both dashed lines. Figure 19 is a projected schematic diagram of the electrode assembly 1 and current collector 3 of a cylindrical battery cell 10 according to other embodiments of this application. Specifically, it is a schematic diagram of the orthographic projection of the electrode assembly 1 and the current collector 3 on a projection plane perpendicular to the first direction Z. In Figure 19, the structure shown by the cross-sectional line is the second welded portion 6, and the first arc M3 and the second arc M4 are both dashed lines. The current collector 3 is welded to the cut-off piece 11221 to form the second welded portion 6.

[0425] The current collector 3 is welded to the second electrode ear winding portion 1122, specifically the current collector 3 is welded to the section 11221 of the second electrode ear winding portion 1122.

[0426] The second welded part 6 refers to the weld mark formed by welding the current collector 3 and the electrode lug 112.

[0427] As an example, as shown in Figure 18, on a projection plane perpendicular to the first direction Z, the orthographic projection of the second welded portion 6 is approximately circular and is arranged around the outer periphery of the central hole 101. As another example, as shown in Figure 19, there are multiple second welded portions 6. On a projection plane perpendicular to the first direction Z, the orthographic projections of multiple second welded portions 6 are spaced apart along the circumferential direction E, and the orthographic projections of multiple second welded portions 6 are arranged together around the outer periphery of the central hole 101.

[0428] As an example, as shown in Figures 4, 6, and 10, in the positive electrode tab 112a, the second welding portion 6 is provided on the winding portion of the second coil portion 11242. In the negative electrode tab 112b, the second welding portion 6 is provided on the first coil portion 11241.

[0429] As an example, as shown in Figures 4 and 10, the second weld portion 6 and the first weld portion 4 are spaced apart in the radial Y direction, with the second weld portion 6 located outside the first weld portion 4. Based on this, the second groove group is located outside the first groove group in the radial Y direction.

[0430] It should be noted that the circumferential direction E refers to the circumferential direction, and the circumferential direction E is approximately perpendicular to the first direction Z.

[0431] In some embodiments, please refer to Figures 4, 6, 10, 18, and 19 together, and in conjunction with other figures. On a projection plane perpendicular to the first direction Z, the two ends of the orthographic projection of the second welding portion 6 have a third projection endpoint N1 and a fourth projection endpoint N2, respectively. The third projection endpoint N1 is closer to the first electrode lug winding portion 1121 than the fourth projection endpoint N2. The area between the third arc line N3, which passes through the third projection endpoint N1 and surrounds the first electrode lug winding portion 1121, and the fourth arc line N4, which passes through the fourth projection endpoint N2 and surrounds the first electrode lug winding portion 1121, is the second transverse region N5. At least some of the cut-off grooves 102 form a second set of grooves. In the second set of grooves, the orthographic projection of the first groove bottom surface 103 of all the cut-off grooves 102 is located within the second transverse region N5.

[0432] Understandably, on the projection plane perpendicular to the first direction Z, the third projection endpoint N1 and the fourth projection endpoint N2 are respectively located at the two ends of the radial Y of the orthographic projection of the second welding part 6. The third arc N3 passes through the third projection endpoint N1, and the fourth arc N4 passes through the fourth projection endpoint N2. Both the third arc N3 and the fourth arc N4 are arranged around the outer periphery of the coiling axis L. The third arc N3 and the fourth arc N4 are spaced apart along the radial Y, and the fourth arc N4 surrounds the outer periphery of the third arc N3, so that the third arc N3 and the fourth arc N4 form a second transverse region N5 spaced apart along the radial Y. The second transverse region N5 is approximately annular. The third arc N3 and the fourth arc N4 are both arranged around the outer periphery of the central hole 101.

[0433] When there are multiple second welding parts 6, on the projection plane perpendicular to the first direction Z, each of the multiple second welding parts 6 has a third projection endpoint N1 and a fourth projection endpoint N2, and the third arc N3 passes through multiple third projection endpoints N1, and the fourth arc N4 passes through multiple fourth projection endpoints N2.

[0434] The third arc N3 and the fourth arc N4 are both arranged around the outer periphery of the central hole 101, the first pole lug winding portion 1121, and the winding axis L. The fourth arc N4 is arranged around the outer periphery of the third arc N3 at intervals, and is arranged radially Y-interval with the third arc N3.

[0435] In the second group of slots, the orthographic projection of the bottom surface 103 of the first slot of all cut-off slots 102 lies within the second transverse region N5. This means that on the projection plane perpendicular to the first direction Z, the orthographic projection of the bottom surface 103 of the first slot of each cut-off slot 102 in the second group of slots is substantially within the second transverse region N5. Specifically, on the projection plane perpendicular to the first direction Z, all cut-off slots 102 whose orthographic projection of the bottom surface 103 of the first slot is substantially within the second transverse region N5 constitute the second group of slots. It can be understood that the portion of the second electrode lug winding portion 1122 where the second welding portion 6 is formed has the aforementioned cut-off slot 102.

[0436] It should be further explained that, on the projection plane perpendicular to the first direction Z, when the orthographic projection of a portion of the first groove bottom surface 103 of a certain cut-off groove 102 is located within the second transverse region N5, the first groove bottom surface 103 of the cut-off groove 102 can be defined as being basically located within the second transverse region N5, and the cut-off groove 102 is defined as one of the cut-off grooves 102 in the second group of grooves.

[0437] As an example, as shown in Figure 4, in the radial Y direction, the first welding portion 4 and the second welding portion 6 are spaced apart, and the first welding portion 4 is located inside the second welding portion 6. Based on this, in the radial Y direction, the first set of grooves is located inside the second set of grooves.

[0438] In some embodiments, please refer to Figures 7 and 15 together, and in conjunction with other figures. In the second set of slots, the number of turns of a single cut-off slot 102 is ≤3.

[0439] The number of turns of a single cut-off groove 102 refers to the number of turns of the first groove bottom surface 103 of a single cut-off groove 102.

[0440] The number of turns of a single cut-off groove 102 can be 1 turn, 2 turns, 3 turns, or less than 1 turn, more than 1 turn and less than 2 turns, more than 2 turns and less than 3 turns, etc.

[0441] As an example, as shown in Figure 15, the cut-off groove 102 shown in Figure 15 has less than one turn.

[0442] In some embodiments, please refer to Figures 7 and 15 together, and in conjunction with other figures. In the second set of slots, the number of cut-off slots 102 that are radially opposite and interconnected along the Y direction of the electrode assembly 1 is ≤3.

[0443] Understandably, on the projection plane perpendicular to the first direction Z, the number of consecutive, opposite, and connected cutoff slots 102 along the radial direction Y is ≤3. On the projection plane perpendicular to the first direction Z, the number of consecutive, opposite, and connected cutoff slots 102 along the radial direction Y can be 3 or 2; or, any two cutoff slots 102 are not opposite and connected along the radial direction Y.

[0444] As an example, as shown in Figure 15, the number of radially opposite and connected cut-off slots 102 can be two.

[0445] By adopting the above technical solution, based on the cutting groove 102 provided in the part of the second electrode winding portion 1122 where the second welding portion 6 is formed, the stacked layer formed by bending in the part of the second electrode winding portion 1122 where the second welding portion 6 is formed will not be too thin due to the setting of the cutting groove 102. Thus, the part of the second electrode winding portion 1122 where the second welding portion 6 is formed can bear the welding penetration of the current collector 3 and the electrode 112, which can improve the problem of laser penetrating the electrode 112 and burning the diaphragm 12 during the welding process of the current collector 3 and the electrode 112. This can improve the problem of short circuit of the electrode assembly 1 caused by the welding of the current collector 3 and the electrode 112 and reduce the risk of short circuit.

[0446] In some embodiments, please refer to Figures 4, 7, 8, 10, and 16 together, and in conjunction with other figures. The second tab winding portion 1122 has a notch 106 near the winding end 105. The notch 106 extends through the winding end 105 along the winding direction W of the electrode assembly 1 and through the end face of the tab 112 facing away from the electrode body 11. The second tab winding portion 1122 has a winding end segment 112222 located at one end of the notch 106 near the electrode body 111. In the first direction Z, the segment 11221 extends beyond the second groove bottom surface 107 of the notch 106 in a direction away from the electrode body 111. The second groove bottom surface 107 is the end face of the winding end segment 112222 facing away from the electrode body 111.

[0447] Understandably, in the first direction Z, the cut piece 11221 extends beyond the winding end section 112222, and the cut piece 11221 and the winding end section 112222 surround to form a notch 106.

[0448] The second groove bottom surface 107 of the notch 106 refers to the groove bottom wall of the notch 106 along the first direction Z, specifically the wall surface of the notch 106 along the first direction Z that is close to the electrode body 111. The second groove bottom surface 107 is formed on the edge of the winding end section 112222 along the first direction Z away from the electrode body 111.

[0449] Specifically, before the cut piece 11221 is bent or in an unfolded state, the notch 106 penetrates the end face of the tab 112 away from the electrode body 111 along the first direction Z.

[0450] Wherein, when the second electrode lug winding portion 1122 includes a transition connection portion 11222, the winding end segment 112222 is a part of the transition connection portion 11222. Understandably, the transition connection portion 11222 may include a winding middle segment 112221 and a winding end segment 112222, which are sequentially connected along the winding direction W of the electrode assembly 1. Both the winding middle segment 112221 and the winding end segment 112222 are located on the edge of the electrode body 111 along the first direction Z near the electrode lug 112, and the winding middle segment 112221 is connected along the first direction Z between the electrode body 111 and the segment 11221. Specifically, along the winding direction W, the winding middle segment 112221 is connected between the first electrode lug winding portion 1121 and the winding end segment 112222.

[0451] When the second electrode lug winding portion 1122 does not include the transition connection portion 11222, the stub 11221 and the winding end segment 112222 are both disposed on the edge of the electrode body 111 along the first direction Z near the electrode lug 112. The winding end segment 112222 and the stub 11221 are sequentially distributed along the winding direction W of the electrode assembly 1, and before the stub 11221 is bent, the size of the stub 11221 along the first direction Z is larger than the size of the winding end segment 112222 along the first direction Z. Specifically, along the winding direction W, all the stubs 11221 are disposed between the first electrode lug winding portion 1121 and the winding end segment 112222.

[0452] This configuration allows the notch 106 to form a channel for venting. Furthermore, the binding effect of the portion of the tab 112 with the notch 106 (which may be, but is not limited to, the winding end section 112222 described below) is reduced, making it easier for the portion of the electrode 11 with the notch 106 to loosen during thermal runaway or even escape through the venting channel formed by the pressure relief section 22111. This improves the directional pressure relief efficiency of the cylindrical battery cell 10.

[0453] In some embodiments, please refer to Figures 4 and 10 together, and in conjunction with other figures. The current collector 3 is welded to the section 11221 of the second tab winding portion 1122, but not to the winding end section 112222. This results in a lower binding force on the portion of the tab 112 with the notched groove 106, making it easier for the portion of the electrode 11 with the notched groove 106 to loosen or even be ejected from the pressure relief portion 22111 during thermal runaway. This facilitates improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0454] The current collector 3 is welded to the section 11221 of the second electrode ear winding portion 1122 to form the second welding portion 6, such that the notch 106 is located outside the first welding portion 4 in the radial Y direction of the electrode assembly 1.

[0455] In this way, with the notch 106, the deposited layer formed by bending the part of the second electrode ear winding portion 1122 where the first welding portion 4 is formed will not be too thin, so that the part of the second electrode ear winding portion 1122 where the first welding portion 4 is formed can bear the welding penetration of the current collector 3 and the electrode terminal 5, which can improve the problem of laser penetrating the electrode ear 112 and burning the diaphragm 12 during the welding process of the current collector 3 and the electrode terminal 5.

[0456] In some embodiments, please refer to Figures 4 and 10 together, and in conjunction with other figures. In the radial Y direction of the electrode assembly 1, the notch 106 is located outside the second weld portion 6.

[0457] By positioning the notch 106 on the outer side of the second weld portion 6 in the radial Y direction of the electrode assembly 1, the deposited layer formed by bending the portion of the second electrode lug winding 1122 where the second weld portion 6 is formed will not be too thin due to the notch 106. This allows the portion of the second electrode lug winding 1122 where the second weld portion 6 is formed to bear the welding penetration of the current collector 3 and the electrode lug 112, thereby improving the problem of laser penetration of the electrode lug 112 and burning of the diaphragm 12 during the welding process of the current collector 3 and the electrode lug 112.

[0458] The above measures can improve the problem of laser penetration of tab 112 and burning of diaphragm 12 during welding, thereby improving the short circuit problem of electrode assembly 1 and reducing the risk of short circuit.

[0459] In some embodiments, please refer to FIG7 and other figures. Among the plurality of segments 11221 of the second electrode winding portion 1122, the segment 11221 farthest from the first electrode winding portion 1121 is wound at least one turn along the winding direction W of the electrode assembly 1.

[0460] As an example, as shown in Figure 7, among the multiple segments 11221 of the second pole ear winding portion 1122, the segment 11221 closest to the winding end 105 is wound multiple times.

[0461] By winding the piece 11221 closest to the winding end 105 at least once, the piece 11221 closest to the winding end 105 can achieve a better wrapping effect on the other pieces 11221. This can improve the problem of internal shorting caused by the piece 11221 turning outward and inserting into the main body P, thereby reducing the risk of short circuit.

[0462] In some embodiments, please refer to FIG8, and in conjunction with other figures. The second electrode ear winding portion 1122 is provided with a plurality of cutting grooves 102, and the cutting grooves 102 and the cutting pieces 11221 are arranged alternately along the winding direction W of the electrode assembly 1.

[0463] Understandably, the number of slices 11221 is at least 3.

[0464] Understandably, multiple cutting grooves 102 are spaced apart on the tab 112 along the winding direction W, and multiple segments 11221 are sequentially arranged on the tab 112 along the winding direction W, with each cutting groove 102 and each segment 11221 arranged alternately along the winding direction W.

[0465] By forming multiple cut-off grooves 102 on the second electrode lug winding portion 1122, the second electrode lug winding portion 1122 can achieve a larger cutting ratio, so that the portion of the electrode sheet 11 with the cut-off grooves 102 can release pressure through the venting channel formed by the pressure relief portion 22111 during thermal runaway, thereby achieving a highly efficient directional pressure relief effect. Furthermore, the deposited layer formed by bending the portion of the second electrode lug winding portion 1122 with the cut-off grooves 102 is not too thin, effectively blocking the laser generated during welding, thus achieving a protective effect on the diaphragm 12. In addition, the multiple cut-off grooves 102 allow the cutting operation of the electrode lug 112 to be adjusted according to actual needs, making the operation of cutting off the electrode lug 112 to form the cut-off grooves 102 highly flexible.

[0466] In some embodiments, as shown in FIG8 and in conjunction with other figures, the dimensions of each of the plurality of cut-off slots 102 in the second electrode ear winding portion 1122 may be the same. For example, the dimensions of each cut-off slot 102 along the winding direction W may be the same. Alternatively, at least two of the plurality of cut-off slots 102 in the second electrode ear winding portion 1122 may have different dimensions.

[0467] In some embodiments, as shown in FIG8 and in conjunction with other figures, the shapes of the plurality of cut-off grooves 102 in the second electrode ear winding portion 1122 may be identical. Alternatively, at least two of the plurality of cut-off grooves 102 in the second electrode ear winding portion 1122 may have different shapes.

[0468] In some embodiments, as shown in FIG8 and in conjunction with other figures, at least two of the plurality of segments 11221 of the second electrode loop winding portion 1122 may have different dimensions. For example, as shown in FIG8, the two segments 11221 may have different dimensions along the winding direction W. Alternatively, the electrode loops 112 in the plurality of segments 11221 of the second electrode loop winding portion 1122 may have the same size.

[0469] As shown in FIG8, the shapes of the multiple segments 11221 of the second electrode ear winding portion 1122 may be the same. Alternatively, at least two segments 11221 of the multiple segments 11221 of the second electrode ear winding portion 1122 may have different shapes.

[0470] In some embodiments, please refer to Figures 8 and 14 together, and in conjunction with other figures. In the first direction Z, the size of the slit 11221 along the winding direction W of the electrode assembly 1 tends to decrease in the direction away from the electrode body 111.

[0471] In the first direction Z, the segment 11221 can be gradually tapered away from the electrode body 111 on one side along the winding direction W of the electrode assembly 1; or, in the first direction Z, the segment 11221 can be gradually tapered away from the electrode body 111 on both sides along the winding direction W of the electrode assembly 1, so that when the electrode 11 is in the unfolded state, the segment 11221 is approximately trapezoidal. Based on this, in the first direction Z, the size of the segment 11221 gradually decreases in the direction away from the electrode body 111 along the winding direction W.

[0472] Accordingly, in the first direction Z, the cutting groove 102 is gradually widened along one or both sides of the winding direction W in a direction away from the electrode body 111, so that in the first direction Z, the size of the cutting groove 102 along the winding direction W gradually increases in a direction away from the electrode body 111.

[0473] By gradually reducing the size of the cut-off piece 11221 in the first direction Z along the winding direction W away from the electrode body 111, it helps to reduce the binding effect of the accumulated layer formed by bending the end region of the cut-off piece 11221 away from the electrode body 111. This helps the portion of the electrode 11 with the cut-off groove 102 to loosen during thermal runaway and be released through the pressure relief section 22111, thereby improving the directional pressure relief efficiency.

[0474] Please refer to Figure 2 and other accompanying drawings. The battery device 100 provided in this application embodiment includes a cylindrical battery cell 10. The cylindrical battery cell 10 in this embodiment is the same as the cylindrical battery cell 10 in the above embodiments; please refer to the relevant descriptions of the cylindrical battery cell 10 in the above embodiments for details, which will not be repeated here.

[0475] The battery device 100 provided in this application adopts the cylindrical battery cell 10 involved in the above embodiments, which enables the battery device 100 to achieve a highly efficient directional pressure relief effect, thereby helping to improve the reliability and performance of the battery device 100.

[0476] Please refer to Figure 1 and other accompanying drawings. The electrical device provided in this application embodiment includes a cylindrical battery cell 10 or a battery device 100. The cylindrical battery cell 10 and battery device 100 in this embodiment are the same as those in the above embodiments; please refer to the relevant descriptions of the cylindrical battery cell 10 and battery device 100 in the above embodiments for details, which will not be repeated here.

[0477] The electrical device provided in this application, by employing the cylindrical battery cell 10 or battery device 100 mentioned above, helps to improve the reliability and performance of the electrical device.

[0478] As one embodiment of this application, as shown in Figures 4 to 9, the cylindrical battery cell 10 includes a housing 2, an electrode assembly 1, and a current collector 3, both of which are disposed within the housing 2. A pressure relief portion 22111 is provided at one end of the housing 2 along the first direction Z. The electrode assembly 1 has a wound structure and a central hole 101 extending along the first direction Z. The electrode assembly 1 includes a positive electrode 11a and a negative electrode 11b. Both the positive and negative electrode 11a include an electrode body 111 and a tab 112 arranged along the first direction Z. The tab 112 and the electrode body 111 are both disposed around the outer periphery of the central hole 101. The tab 112 of the positive electrode 11a and the tab 112 of the negative electrode 11b are respectively located at both ends of the electrode assembly 1 along the first direction Z. Electrode assembly 1 has current collectors 3 at both ends along the first direction Z, and the current collectors 3 at both ends are a first current collector 3a and a second current collector 3b, respectively. The first current collector 3a is disposed between the positive electrode tab 112a and the wall of the outer casing 2 along the first direction Z, and the second current collector 3b is disposed between the negative electrode tab 112b and the wall of the outer casing 2 along the first direction Z. The tab 112 includes a first tab winding portion 1121 and a second tab winding portion 1122, both of which are disposed around the outer periphery of the central hole 101. The second tab winding portion 1122 surrounds the outer periphery of the first tab winding portion 1121 and is connected to the first tab winding portion 1121. The electrode 11 includes a first electrode winding portion 114 and a second electrode winding portion 115. A first electrode loop winding portion 1121 is formed at one end of the first electrode winding portion 114 along a first direction Z, and a second electrode loop winding portion 1122 is formed at one end of the second electrode winding portion 115 along the first direction Z. In the first direction Z, the second electrode loop winding portion 1122 extends beyond the first electrode loop winding portion 1121 in a direction away from the electrode body 111. A first current collector 3a is welded to the second electrode loop winding portion 1122 of the positive electrode loop 112a, but not to the first electrode loop winding portion 1121 of the positive electrode loop 112a. A second current collector 3b is welded to the second electrode loop winding portion 1122 of the negative electrode loop 112b, but not to the first electrode loop winding portion 1121 of the negative electrode loop 112b. On a projection plane perpendicular to the first direction Z, the orthographic projection of the center hole 101 and the orthographic projection of the first electrode lug winding portion 1121 are both located within the orthographic projection of the pressure relief portion 22111. The pressure relief portion 22111 is configured to at least partially open to form an exhaust passage during pressure relief, through which at least a portion of the electrode 11 is released to the outside of the housing 2.

[0479] The above are merely optional 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 scope of the claims of this application.

Claims

1. A cylindrical battery cell, wherein, include: The outer casing has a pressure relief section at at least one end along the first direction; An electrode assembly, at least partially disposed within the housing, is a wound structure and includes two electrodes with opposite polarities. At least one of the electrodes includes an electrode body and an electrode tab arranged along the first direction. The electrode body is coated with an active material layer, and at least a portion of the electrode tab is not coated with the active material layer. The electrode lug includes a first electrode lug winding portion and a second electrode lug winding portion disposed outside the first electrode lug winding portion. In the first direction, the second electrode lug winding portion extends beyond the first electrode lug winding portion in a direction away from the electrode body. On a projection plane perpendicular to the first direction, the orthographic projection of the first electrode lug winding portion is located within the orthographic projection of the pressure relief portion. The pressure relief portion is configured to at least partially open and form an exhaust channel when pressure is released, through which at least a portion of the electrode is released to the outside of the housing.

2. The cylindrical battery cell according to claim 1, wherein, The electrode assembly has a winding axis parallel to the first direction, and the second electrode ear winding portion has a bent section at one end in the first direction; The bending section includes a first bending portion that bends relative to the electrode body in a direction close to the winding axis, and / or the bending section includes a second bending portion that bends relative to the electrode body in a direction away from the winding axis.

3. The cylindrical battery cell according to claim 1 or 2, wherein, In the winding direction of the electrode assembly, the length of the second electrode lug winding portion is greater than the length of the first electrode lug winding portion.

4. The cylindrical battery cell according to any one of claims 1-3, wherein, The electrode includes a first electrode winding portion and a second electrode winding portion disposed outside the first electrode winding portion. The first electrode winding portion is formed at one end of the first electrode winding portion along the first direction, and the second electrode winding portion is formed at one end of the second electrode winding portion along the first direction. On a projection plane perpendicular to the first direction, the orthographic projection of the first electrode winding portion is located within the orthographic projection of the pressure relief portion. At least a portion of the first electrode winding portion is released to the outside of the housing through the exhaust channel during pressure relief.

5. The cylindrical battery cell according to claim 4, wherein, At least one of the electrode sheets has a winding start end and a winding end end at both ends along the winding direction of the electrode assembly, the winding end being formed in the second electrode sheet winding portion and the winding start end being formed in the first electrode sheet winding portion.

6. The cylindrical battery cell according to claim 4 or 5, wherein, The electrode assembly has a central hole extending along the first direction. On a projection plane perpendicular to the first direction, the orthographic projection of the central hole is located within the orthographic projection of the pressure relief portion. The first electrode winding portion is arranged around the outer periphery of the central hole.

7. The cylindrical battery cell according to claim 6, wherein, The outer diameter of the electrode assembly is D1, and the diameter of the central hole is D2, where D2 / D1 ∈ [5%, 25%].

8. The cylindrical battery cell according to any one of claims 1-7, wherein, Both electrodes include an electrode body and an electrode tab. The electrode tabs of the two electrodes are respectively disposed at both ends of the electrode assembly along the first direction. Each electrode tab includes a first electrode tab winding portion and a second electrode tab winding portion. On a projection plane perpendicular to the first direction, the orthographic projection of the first electrode tab winding portion of each electrode tab is located within the orthographic projection of the pressure relief portion.

9. The cylindrical battery cell according to any one of claims 1-8, wherein, The two electrodes include a positive electrode and a negative electrode, wherein the tabs of the positive electrode and / or the tabs of the negative electrode are not coated with the active material layer.

10. The cylindrical battery cell according to any one of claims 1-9, wherein, The cylindrical battery cell also includes a current collector, at least a portion of which is disposed within the housing. The current collector is welded to the second tab winding portion but not to the first tab winding portion.

11. The cylindrical battery cell according to claim 10, wherein, The cylindrical battery cell also includes an electrode terminal, which is fixed to the housing and welded to the current collector to form a first welded portion. In the radial direction of the electrode assembly, the first welded portion is located outside the first tab winding portion.

12. The cylindrical battery cell according to claim 10 or 11, wherein, Both electrodes include an electrode body and a tab, wherein the tab of one electrode is a first tab and the tab of the other electrode is a second tab, and the first tab and the second tab are respectively disposed at both ends of the electrode assembly along the first direction. The first tab and the second tab each include a first tab winding portion and a second tab winding portion. On a projection plane perpendicular to the first direction, the orthographic projection of the first tab winding portion of the first tab and the orthographic projection of the first tab winding portion of the second tab are both located within the orthographic projection of the pressure relief portion. In the first direction, both ends of the electrode assembly are provided with current collecting components, and the current collecting components at both ends of the electrode assembly are respectively a first current collecting component and a second current collecting component. The first current collecting component is welded to the second electrode winding portion of the first electrode tab, and the second current collecting component is welded to the second electrode winding portion of the second electrode tab.

13. The cylindrical battery cell according to claim 12, wherein, The housing includes a first end wall, a second end wall, and a side wall. The first end wall and the second end wall are respectively disposed at both ends of the side wall along the first direction, and the second end wall is provided with an electrode terminal. The first electrode tab is electrically connected to the electrode terminal through the first current collector, and the second electrode tab is electrically connected to the side wall through the second current collector.

14. The cylindrical battery cell according to claim 13, wherein, The first end wall is welded to the second current collector, and the first end wall is electrically connected to the side wall.

15. The cylindrical battery cell according to claim 13 or 14, wherein, In the radial direction of the electrode assembly, the sidewall protrudes inward to form a protrusion, the protrusion and the electrode assembly are distributed along the first direction, and the second current collector is welded to the side of the protrusion close to or away from the electrode assembly.

16. The cylindrical battery cell according to any one of claims 13-15, wherein, The first end wall is provided with the pressure relief section.

17. The cylindrical battery cell according to any one of claims 13-16, wherein, The first electrode is the positive electrode, and the second electrode is the negative electrode.

18. The cylindrical battery cell according to any one of claims 10-17, wherein, The flow collecting component is provided with an exhaust port extending along the first direction, and the exhaust port and the pressure relief part are arranged opposite to each other along the first direction; The flow collector is provided with multiple guide portions, which are spaced apart around the outer periphery of the exhaust port.

19. The cylindrical battery cell according to claim 18, wherein, The guide portion extends to the exhaust port; Alternatively, the guide portion is spaced apart from the wall of the exhaust hole, and the minimum distance between the guide portion and the wall of the exhaust hole is less than or equal to 10 mm.

20. The cylindrical battery cell according to claim 18 or 19, wherein, On a projection plane perpendicular to the first direction, along the radial direction of the electrode assembly, the orthographic projection of the end of the guide portion away from the exhaust port is located outside the outer contour of the orthographic projection of the pressure relief portion or coincides with the outer contour of the orthographic projection of the pressure relief portion.

21. The cylindrical battery cell according to any one of claims 18-20, wherein, The guide portion includes a through hole penetrating the current collecting member along the first direction; And / or, the guide portion includes a second groove that does not penetrate the flow collector member along the first direction.

22. The cylindrical battery cell according to any one of claims 18-21, wherein, The electrode assembly has a central hole extending along the first direction. On a projection plane perpendicular to the first direction, the orthographic projection of the central hole is located within the orthographic projection of the pressure relief portion. The central hole and the exhaust port are opposite to and connected along the first direction, and the first electrode lug winding portion is arranged around the outer periphery of the central hole.

23. The cylindrical battery cell according to any one of claims 1-22, wherein, On a projection plane perpendicular to the first direction, a portion of the orthographic projection of the second electrode ear winding portion lies within the orthographic projection of the pressure relief portion.

24. The cylindrical battery cell according to any one of claims 1-23, wherein, The second electrode ear winding portion includes a plurality of truncated pieces that are bent and distributed along the winding direction of the electrode assembly. A cutting groove is provided between any two adjacent truncated pieces along the winding direction of the electrode assembly. On a projection plane perpendicular to the first direction, the orthographic projection of the bottom surface of the first groove of at least one cutting groove is located within the orthographic projection of the pressure relief portion.

25. The cylindrical battery cell according to claim 24, wherein, The two electrodes include a positive electrode and a negative electrode. The tabs of the positive electrode and / or the tabs of the negative electrode are not coated with the active material layer. In the first direction, in the positive electrode, the end region of the tab near the electrode body is provided with an insulating layer, and the cut-off piece is located on the side of the insulating layer away from the electrode body.

26. The cylindrical battery cell according to claim 24 or 25, wherein, The second electrode winding portion further includes a transition connection portion connected to the first electrode winding portion. The electrode body, the transition connection portion, and the segment are arranged sequentially along the first direction. The transition connection portion and any two segments adjacent to each other along the winding direction of the electrode assembly form the cut-off groove. The bottom surface of the first groove of the cut-off groove is formed on one side edge of the transition connection portion used to connect the segment.

27. The cylindrical battery cell according to claim 26, wherein, The dimension of one side edge of each of the segments used to connect the transition connection portion in the winding direction of the electrode assembly is H1, and the dimensions of the transition connection portion and the segments in the first direction are H2, where 0.01≤H2 / H1≤0.

3.

28. The cylindrical battery cell according to claim 26 or 27, wherein, The dimension of the transition connection in the first direction is H3, where 0.1mm ≤ H3 ≤ 2mm.

29. The cylindrical battery cell according to any one of claims 24-28, wherein, The cylindrical battery cell further includes a current collector and electrode terminals. At least a portion of the current collector is disposed inside the housing. The electrode terminals are fixed to the housing and welded to the current collector to form a first welded portion. On the projection plane perpendicular to the first direction, the two ends of the orthographic projection of the first welded part have a first projection endpoint and a second projection endpoint, respectively. The first projection endpoint is closer to the first electrode ear winding part than the second projection endpoint. The area between the first arc line that passes through the first projection endpoint and surrounds the first electrode ear winding part and the second arc line that passes through the second projection endpoint and surrounds the first electrode ear winding part is the first transverse area. At least a portion of the cut-off grooves form a first group of grooves. In the first group of grooves, the orthographic projection of the bottom surface of the first groove of all the cut-off grooves is located within the first transverse area. Wherein, in the first group of slots, the number of turns of a single cut-off slot is ≤3; and / or, in the first group of slots, the number of cut-off slots that are radially opposite and interconnected along the electrode assembly is ≤3.

30. The cylindrical battery cell according to any one of claims 24-29, wherein, The cylindrical battery cell further includes a current collector, at least a portion of which is disposed within the housing. The current collector is welded to the sectional section to form a second welded portion. On the projection plane perpendicular to the first direction, the two ends of the orthographic projection of the second welding part have a third projection endpoint and a fourth projection endpoint, respectively. The third projection endpoint is closer to the first electrode ear winding part than the fourth projection endpoint. The area between the third arc line that passes through the third projection endpoint and surrounds the first electrode ear winding part and the fourth arc line that passes through the fourth projection endpoint and surrounds the first electrode ear winding part is the second transverse region. At least a portion of the cut-off grooves form a second group of grooves. In the second group of grooves, the orthographic projection of the bottom surface of the first groove of all the cut-off grooves is located within the second transverse region. Wherein, in the second group of slots, the number of turns of a single cut-off slot is ≤3; and / or, in the second group of slots, the number of cut-off slots that are radially opposite and interconnected along the electrode assembly is ≤3.

31. The cylindrical battery cell according to any one of claims 24-30, wherein, At least one of the electrode sheets has a winding start end and a winding end end at both ends along the winding direction of the electrode assembly. The second electrode tab winding portion near the winding end is provided with a notch groove. The notch groove passes through the winding end along the winding direction of the electrode assembly and passes through the end face of the electrode tab away from the electrode sheet body. The second electrode ear winding portion has a winding end section located at one end of the notch near the electrode body. In the first direction, the cut piece extends beyond the bottom surface of the second groove of the notch in a direction away from the electrode body. The bottom surface of the second groove is the end face of the winding end section away from the electrode body.

32. The cylindrical battery cell according to any one of claims 24-31, wherein, In the plurality of segments of the second electrode winding portion, the segment furthest from the first electrode winding portion is wound at least one turn along the winding direction of the electrode assembly.

33. The cylindrical battery cell according to any one of claims 24-32, wherein, The second electrode ear winding portion is provided with a plurality of cutting grooves, and the cutting grooves and the cutting pieces are arranged alternately along the winding direction of the electrode assembly.

34. The cylindrical battery cell according to any one of claims 24-33, wherein, In the first direction, the size of the truncated piece along the winding direction of the electrode assembly tends to decrease in the direction away from the electrode body.

35. The cylindrical battery cell according to any one of claims 24-30, wherein, The electrode assembly has a winding axis parallel to the first direction, and at least one of the segments has a bent section at one end in the first direction; The bending section includes a first bending portion that bends relative to the electrode body in a direction close to the winding axis, and / or the bending section includes a second bending portion that bends relative to the electrode body in a direction away from the winding axis.

36. The cylindrical battery cell according to claim 35, wherein, Each of the segments has a bent section at one end in the first direction.

37. The cylindrical battery cell according to claim 2, 35, or 36, wherein, The first bending portion is bent radially along the electrode assembly; and / or, the second bending portion is bent radially along the electrode assembly.

38. The cylindrical battery cell according to any one of claims 2 or 35-37, wherein, The bending segment includes at least one first bending portion and at least one second bending portion, the first bending portion and the second bending portion being alternately arranged along the first direction.

39. The cylindrical battery cell according to any one of claims 1-38, wherein, The housing also includes a first end wall opposite to the electrode assembly along the first direction, the first end wall having a first groove and the pressure relief portion located in the area enclosed by the first groove, the bottom of the first groove having a weak portion, the pressure relief portion being connected to the weak portion, at least a portion of the weak portion being configured to disconnect upon pressure relief to open the pressure relief portion.

40. The cylindrical battery cell according to any one of claims 1-38, wherein, The housing also includes a first wall and a pressure relief mechanism. The first wall is disposed opposite to the electrode assembly along the first direction. The first wall is fixedly connected to the pressure relief mechanism. The pressure relief mechanism has a first groove and a pressure relief portion located in the area enclosed by the first groove. The bottom of the first groove has a weak portion. The pressure relief portion is connected to the weak portion. At least a portion of the weak portion is configured to be disconnected during pressure relief to open the pressure relief portion.

41. The cylindrical battery cell according to any one of claims 1-40, wherein, On a projection plane perpendicular to the first direction, the outer contour of the orthographic projection of the pressure relief part is circular.

42. A battery device, wherein, Includes the cylindrical battery cell according to any one of claims 1-41.

43. An electrical appliance, wherein, It includes a cylindrical battery cell according to any one of claims 1-41; or, it includes a battery device according to claim 42.

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