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) provided with a pressure relief portion (22111) and an electrode assembly (1) provided with a central hole (101). At least one electrode sheet (11) of the electrode assembly (1) comprises a tab (112). The tab (112) comprises a plurality of cut pieces (1121), at least one cut piece (1121) is bent towards the central hole (101), at least one cut piece (1121) is bent away from the central hole (101), a cut-off groove (102) is provided between any two adjacent cut pieces (1121), and the orthographic projection of the central hole (101) and the orthographic projection of a first groove bottom surface (103) of at least one cut-off groove (102) are both located within the orthographic projection of the pressure relief portion (22111). In this way, the 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, and the capacity of battery devices is becoming larger, while the performance requirements for battery devices are also becoming more 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 are typically all tabs. After the electrode sheets are wound, the tabs can be bent, which gives the tabs a strong binding effect, thus strongly hindering the release of high-temperature, high-pressure media during thermal runaway. This restricts the release of the high-temperature, high-pressure media generated during thermal runaway, and the rate at which this media spreads towards the pressure relief mechanism on the casing is low, 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 housing has a pressure relief section at at least one end along a first direction, and the pressure relief section is configured to open at least partially when pressure is released;

[0010] An electrode assembly, at least partially disposed within a housing, is a wound structure and has a central hole extending along a first direction. The electrode assembly includes two electrodes with opposite polarities. At least one electrode 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 an active material layer. Both the electrode tab and the electrode body are disposed around the outer periphery of the central hole.

[0011] The electrode tab includes multiple segments that are bent and distributed along the winding direction of the electrode assembly. At least one segment of the multiple segments is bent toward the direction close to the central hole, and at least one segment of the multiple segments is bent away from the central hole. Along the winding direction of the electrode assembly, a cutting groove is provided between any two adjacent segments. On the projection plane perpendicular to the first direction, the orthographic projection of the central hole and the orthographic projection of the bottom surface of the first groove of at least one cutting groove are both located within the orthographic projection of the pressure relief part.

[0012] The cylindrical battery cell provided in this application embodiment includes a tab of an electrode assembly comprising multiple bent segments distributed along the winding direction of the electrode assembly. A cutting groove is formed between any two adjacent segments along the winding direction of the electrode assembly, thereby reducing the density of the deposited layer formed by the portion of the tab with the cutting groove. A pressure relief portion is provided at least at one end of the outer casing along a first direction. In this first direction, the orthographic projection of the central hole and the orthographic projection of the bottom surface of the first groove of at least one cutting groove are both located within the orthographic projection of the pressure relief portion. This reduces the self-binding effect of the tab on the portion of the pressure relief portion under the action of the cutting groove, thereby also reducing the mutual binding effect of the electrode segments on the portion of the pressure relief portion. During the thermal runaway of a cylindrical battery cell, the binding effect of the tabs on at least part of the pressure relief section is easily broken by the gas pressure. This allows at least part of the electrode sheet facing the pressure relief section to loosen under the pressure. This reduces the obstruction of the tabs to the high-temperature and high-pressure medium, making it easier for the high-temperature and high-pressure medium to spread towards the pressure relief section and be released outside the casing through the exhaust channel formed by the opening of the pressure relief section. This can improve the discharge rate and efficiency of the high-temperature and high-pressure medium, enabling the cylindrical battery cell to achieve a highly efficient directional pressure relief effect.

[0013] In some embodiments, the pressure relief section is configured to at least partially open and form an exhaust passage during pressure relief, through which at least a portion of the electrode is discharged to the outside of the housing.

[0014] With this configuration, during the thermal runaway of a cylindrical battery cell, when the pressure inside the casing reaches a threshold, the pressure relief section opens to form an exhaust channel. As the binding effect of the tabs is reduced, at least part of the electrode sheet can be loosened under the action of air pressure and released to the outside of the casing through the exhaust channel. This can improve the directional pressure relief effect of the cylindrical battery cell.

[0015] In some embodiments, at least one end of the electrode sheet is provided with a bent section in a first direction. The bent section includes at least one first bent portion bent relative to the electrode body in a direction close to the central hole and at least one second bent portion bent relative to the electrode body in a direction away from the central hole.

[0016] This configuration allows the end region of the tab that is away from the electrode body along the first direction to be bent, thereby forming a relatively dense stacked layer.

[0017] In some embodiments, both the first bend and the second bend are arranged to bend radially along the electrode assembly.

[0018] This design allows the tabs to bend more effectively.

[0019] In some embodiments, the first bend and the second bend are alternately arranged along a first direction.

[0020] This configuration allows the end region of the tab that is away from the electrode body along the first direction to be bent, thereby forming a relatively dense stacked layer.

[0021] In some embodiments, each segment has a bent section at one end in a first direction.

[0022] This configuration allows the end region of the tab that is away from the electrode body along the first direction to be bent, thereby forming a relatively dense stacked layer.

[0023] 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 multiple segments. On a projection plane perpendicular to the first direction, the orthographic projection of the bottom surface of the first groove of at least one cut-off groove on the electrode tab of each electrode is located within the orthographic projection of the pressure relief portion.

[0024] 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 helping to improve the reliability of the cylindrical battery cell.

[0025] 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.

[0026] This allows the cut-off groove to be formed in the part of the electrode where the active material layer is not set, which can, to a certain extent, ensure the performance of the active material layer, thereby ensuring the performance of the electrode assembly and thus ensuring the charge and discharge performance of the cylindrical battery cell.

[0027] In some embodiments, in a first direction, on the positive electrode sheet, an insulating layer is provided in the end region of the tab near the electrode sheet body, and the cut-off piece is located on the side of the insulating layer away from the electrode sheet body.

[0028] This allows the positive electrode to have an insulating layer, which effectively improves the short circuit problem between the positive and negative electrodes.

[0029] In some embodiments, the electrode tab further includes a transition connection 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 cut-off groove, and the first groove bottom surface of the cut-off groove is formed on one side edge of the transition connection portion for connecting the slit.

[0030] 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.

[0031] 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 L1, and the sum of the dimensions of the transition connection portion and the segment in the first direction is L2, where 0.01≤L2 / L1≤0.3.

[0032] 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.

[0033] In some embodiments, the dimension of the transition connection in the first direction is L3, where 0.1mm≤L3≤2mm.

[0034] This design allows the transition connection to have a certain size in the first direction. Based on the fact that the tab can form a cutting groove, the transition connection can block the cut piece, thereby improving the problem of the cut piece bending and inserting into the main body.

[0035] 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.

[0036] 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 under the action of air pressure through the pressure relief section.

[0037] 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.

[0038] 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 under the action of air pressure through the pressure relief section.

[0039] 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.

[0040] 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 cylindrical battery cell.

[0041] 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, and the winding start end is closer to the center hole than the winding end end in the radial direction of the electrode assembly.

[0042] The portion of the electrode tab near the starting end of winding is provided with a first notch. The first notch penetrates the starting end of winding along the winding direction of the electrode assembly and penetrates the end face of the electrode tab away from the electrode body along the first direction.

[0043] The tab has a winding start section located at one end of the first notch near the electrode body. In a first direction, the tab extends beyond the bottom surface of the second groove of the first notch in a direction away from the electrode body. The bottom surface of the second groove is the end face of the winding start section away from the electrode body.

[0044] In this way, the binding effect of the portion of the electrode with the first notch can be reduced, which makes it easier for the electrode to release pressure outside the casing through the pressure relief section during thermal runaway, thereby improving the directional pressure relief efficiency of the cylindrical battery cell.

[0045] In some embodiments, the cylindrical battery cell further includes a current collector, at least a portion of which is disposed within the housing;

[0046] On the projection plane perpendicular to the first direction, the orthographic projection of the winding start section is located within the orthographic projection of the pressure relief section. The current collection component is welded to the slab but not to the winding start section.

[0047] By welding the current collector to the electrode sheet but not to the winding start section, the binding effect of the part of the electrode sheet with the first notch is lower. This makes it easier for the part of the electrode sheet with the first notch to release pressure through the pressure relief section under the action of air pressure during the thermal runaway of the cylindrical battery cell, thereby improving the directional pressure relief efficiency of the cylindrical battery cell.

[0048] 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, and the winding start end is closer to the center hole than the winding end end in the radial direction of the electrode assembly.

[0049] The portion of the electrode tab near the winding end is provided with a second notch. The second notch penetrates the winding end along the winding direction of the electrode assembly and penetrates the end face of the electrode tab away from the electrode body along the first direction.

[0050] The tab has a wound end section located at one end of the second notch near the electrode body. In a first direction, the tab extends beyond the bottom surface of the third groove of the second notch in a direction away from the electrode body. The bottom surface of the third groove is the end face of the wound end section away from the electrode body.

[0051] This design allows the second notch to form a channel for venting. Furthermore, the binding effect on the portion of the electrode with the second notch (which may, but is not limited to, the winding end section described below) is reduced, making it easier for this portion to loosen or even eject from the pressure relief section during thermal runaway. This, in turn, improves the directional pressure relief efficiency of the cylindrical battery cell.

[0052] In some embodiments, the cylindrical battery cell further includes a current collector, at least a portion of which is disposed within the housing;

[0053] The current collector is welded to the cut section, but not to the end of the winding.

[0054] By welding the current collector to the electrode section but not to the winding end, the binding effect on the portion of the electrode with the second notch is reduced, making it easier for this portion to loosen or even eject from the pressure relief section during thermal runaway. This, in turn, improves the directional pressure relief efficiency of the cylindrical battery cell.

[0055] In some embodiments, the cylindrical battery cell further includes a current collector, at least a portion of which is disposed within the housing, and the current collector is welded to the slab to form a first welded portion.

[0056] By welding the current collector and the electrode tab, the current collector can collect current for the electrode assembly, making it easier for the current transmission end of the cylindrical battery cell to be electrically connected to the electrode assembly, thus facilitating the use of the cylindrical battery cell.

[0057] In some embodiments, on the projection plane perpendicular to the first direction, the two ends of the orthographic projection of the first weld portion have a first projection endpoint and a second projection endpoint, respectively. The first projection endpoint is closer to the center hole than the second projection endpoint. The area between the first arc line passing through the first projection endpoint and surrounding the center hole and the second arc line passing through the second projection endpoint and surrounding the center hole is the first transverse region. At least some of the cut-off grooves form a first group of grooves, and 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 region.

[0058] 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.

[0059] By adopting the above technical solution, the deposited layer formed by bending the part of the electrode with the first welded part is not too thin due to the setting of the cut-off groove, so that the part of the electrode with the first welded part can bear the welding penetration of the current collector and the electrode. This can improve the problem of laser penetration of the electrode and burning of the diaphragm during the welding process of the current collector and the electrode, thereby improving the problem of short circuit of the electrode assembly caused by the welding of the current collector and the electrode and reducing the risk of short circuit.

[0060] In some embodiments, the cylindrical battery cell further includes electrode terminals fixed to the housing, which are welded to the current collector to form a second welded portion.

[0061] This configuration allows for electrical connection between the electrode terminals and the electrode assembly.

[0062] In some embodiments, on the projection plane perpendicular to the first direction, the two ends of the orthographic projection of the second weld portion have a third projection endpoint and a fourth projection endpoint, respectively. The third projection endpoint is closer to the center hole than the fourth projection endpoint. The area between the third arc line that passes through the third projection endpoint and surrounds the center hole and the fourth arc line that passes through the fourth projection endpoint and surrounds the center hole is the second transverse region. At least some of the cut-off grooves form a second set of grooves. In the second set 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.

[0063] 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.

[0064] By adopting the above technical solution, the deposited layer formed by bending the part of the electrode with the second welded part is not too thin due to the setting of the cut-off groove, so that the part of the electrode with the second welded part can bear the welding penetration of the current collector and the electrode terminal. This can improve the problem of laser penetration of the electrode and burning of the diaphragm during the welding process of the current collector and the electrode terminal, thereby improving the problem of short circuit of the electrode assembly caused by welding of the current collector and the electrode terminal and reducing the risk of short circuit.

[0065] 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, and the winding start end is closer to the center hole than the winding end end in the radial direction of the electrode assembly.

[0066] The portion of the electrode tab near the starting end of winding is provided with a first notch. The first notch penetrates the starting end of winding along the winding direction of the electrode assembly and penetrates the end face of the electrode tab away from the electrode body along the first direction.

[0067] The tab has a winding start section located at one end of the first notch near the electrode body. In a first direction, the tab extends beyond the bottom surface of the second groove of the first notch in a direction away from the electrode body. The bottom surface of the second groove is the end face of the winding start section away from the electrode body.

[0068] In the radial direction of the electrode assembly, a first weld portion is located outside the first notch groove; and / or, in the radial direction of the electrode assembly, a second weld portion is located outside the first notch groove.

[0069] 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.

[0070] 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; in the radial direction of the electrode assembly, the winding start end is closer to the center hole than the winding end end.

[0071] The portion of the electrode tab near the winding end is provided with a second notch. The second notch penetrates the winding end along the winding direction of the electrode assembly and penetrates the end face of the electrode tab away from the electrode body along the first direction.

[0072] The tab has a wound end section located at one end of the second notch near the electrode body. In the first direction, the tab extends beyond the bottom surface of the third groove of the second notch in a direction away from the electrode body. The bottom surface of the third groove is the end face of the wound end section away from the electrode body.

[0073] In the radial direction of the electrode assembly, the second notch is located outside the first weld portion; and / or, in the radial direction of the electrode assembly, the second notch is located outside the second weld portion.

[0074] 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.

[0075] 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 a first direction.

[0076] 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 the first current collecting component and the second current collecting component, respectively.

[0077] 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 located at both ends of the side wall along a first direction, and electrode terminals are provided on the second end wall.

[0078] The first current collector is welded to the segment of the first electrode tab and electrically connected to the electrode terminal. The second current collector is welded to the segment of the second electrode tab and electrically connected to the side wall.

[0079] 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.

[0080] In some embodiments, the second current collector is welded to the first end wall, and the side wall is electrically connected to the first end wall.

[0081] This configuration allows the second current collector to be indirectly electrically connected to the sidewall via the first end wall.

[0082] In some embodiments, 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 a first direction, and a second current collector is welded to the side of the protrusion close to or away from the electrode assembly.

[0083] This configuration allows the second current collector to be directly electrically connected to the sidewall.

[0084] In some embodiments, the first electrode is a positive electrode and the second electrode is a negative electrode.

[0085] 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.

[0086] In some embodiments, a pressure relief portion is provided on the first end wall.

[0087] 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.

[0088] In some embodiments, the current collecting member is provided with an exhaust vent extending in a first direction, the exhaust vent being opposite to and communicating with the central hole in the first direction;

[0089] The flow collector is also provided with multiple guide sections, which are spaced apart around the outer periphery of the exhaust port.

[0090] 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 air pressure to form an exhaust channel. The guide section can also disconnect under air pressure, causing the current collector to deform and open towards the pressure relief section, thereby gradually increasing the diameter of the exhaust orifice. This facilitates the movement of the electrode plates towards the pressure relief section, allowing them to be released through the exhaust orifice and exhaust channel to the outside of the casing. This design helps improve the directional pressure relief efficiency of the cylindrical battery cell.

[0091] In some embodiments, the guide extends to the exhaust port;

[0092] 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.

[0093] 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.

[0094] 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.

[0095] By adopting the above technical solution, the guide section is disconnected under air pressure, allowing the current collector to deform and open towards the pressure relief section, thus increasing the diameter of the vent hole to a greater extent. In this way, during thermal runaway of the cylindrical battery cell, when the electrode is released to the outside of the casing through the venting channel formed by the opening of the pressure relief section, the obstruction effect of the current collector on the electrode is reduced, which helps improve the efficiency of the electrode releasing pressure through the venting channel, thereby improving the directional pressure relief efficiency of the cylindrical battery cell.

[0096] In some embodiments, the guide portion includes a through hole extending through the current collecting member in a first direction;

[0097] Alternatively, the guide may include a second groove that does not penetrate the flow collector in the first direction.

[0098] By adopting the above technical solution, the guiding 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 improving the directional pressure relief effect of the cylindrical battery cell.

[0099] 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, and the winding start end is closer to the center hole than the winding end end in the radial direction of the electrode assembly.

[0100] Among the multiple segments of the tab, the segment closest to the winding end is wound at least once.

[0101] 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.

[0102] In some embodiments, the tab is provided with a plurality of cut-off grooves, and the cut-off grooves and the cut pieces are arranged alternately in the winding direction of the electrode assembly.

[0103] By forming multiple cut-off grooves on the electrode tab, a larger removal ratio can be achieved, allowing the portion of the electrode with cut-off grooves to release pressure through 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 electrode tab with cut-off grooves is not too thin, effectively blocking the laser generated during welding, thereby achieving a protective effect on the diaphragm.

[0104] 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.

[0105] 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 pressure through the pressure relief structure, which helps to improve the directional pressure relief efficiency.

[0106] 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%].

[0107] 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.

[0108] Secondly, embodiments of this application provide a battery device, including a cylindrical battery cell.

[0109] 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.

[0110] Thirdly, embodiments of this application provide an electrical device, including a cylindrical battery cell or a battery device.

[0111] 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.

[0112] 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

[0113] 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.

[0114] Figure 1 is a schematic diagram of a vehicle provided in some embodiments of this application;

[0115] Figure 2 is an exploded view of a battery device provided in some embodiments of this application;

[0116] Figure 3 is a schematic diagram of a cylindrical battery cell provided in some embodiments of this application;

[0117] Figure 4 is a cross-sectional view of Figure 3 along AA;

[0118] Figure 5 is a schematic diagram of the electrode assembly of the cylindrical battery cell shown in Figure 3;

[0119] Figure 6 is an enlarged view of point B in Figure 4;

[0120] Figure 7 is an enlarged view of point C in Figure 4;

[0121] Figure 8 is a schematic diagram showing the unfolded electrode of the cylindrical battery cell provided in Figure 3;

[0122] Figure 9 is an enlarged view of point D in Figure 8;

[0123] Figure 10 is a projected schematic diagram of the pressure relief section and the tab of the cylindrical battery cell shown in Figure 3.

[0124] Figure 11 is an enlarged view of point E in Figure 10;

[0125] Figure 12 is a partial unfolded schematic diagram of the positive electrode sheet of the cylindrical battery cell shown in Figure 3;

[0126] Figure 13 is a partial unfolded schematic diagram of the negative electrode sheet of the cylindrical battery cell provided in Figure 3;

[0127] Figure 14 is an enlarged view of point F in Figure 4;

[0128] Figure 15 is an enlarged view of point G in Figure 8;

[0129] Figure 16 is an enlarged view of point H in Figure 8;

[0130] Figure 17 is a schematic projection of the electrode assembly and current collector of a cylindrical battery cell provided in some embodiments of this application;

[0131] Figure 18 is a schematic projection of the electrode assembly and current collector of a cylindrical battery cell provided in some other embodiments of this application;

[0132] Figure 19 is a projected schematic diagram of the electrode assembly, current collector and electrode terminals of the cylindrical battery cell shown in Figure 3.

[0133] Figure 20 is a partial cross-sectional view of a cylindrical battery cell provided in some other embodiments of this application;

[0134] Figure 21 is a schematic projection of the current collector and pressure relief section of the cylindrical battery cell shown in Figure 3.

[0135] 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-First notched groove; 107-Bottom of the second groove; 108-Second notched groove; 109-Bottom of the third 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; 112-Taper; 112 a-Positive electrode tab; 112b-Negative electrode tab; 1121-Cut piece; 11211-Bent section; 112111-First bend; 112112-Second bend; 1122-Transition connection; 11221-Winding start section; 11222-Winding end section; 11223-Winding middle section; 113-Insulating layer; 12-Diaphragm; 2-Outer shell; 201-First groove; 202-Roll groove; 21-Shell; 211-Second end 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 vent; 31-Current collector body; 32-Guide part; 321-First edge; 4-First welding part; 5-Electrode terminal; 6-Second welding part; 2 0 - 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; Z - First direction; Y - Radial; E - Circumferential; W - Winding direction; X - Length direction. Detailed Implementation

[0136] 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.

[0137] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] A cylindrical battery cell may include a cylindrical outer casing and electrode components disposed within 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 formed by the pressure relief mechanism, achieving a directional pressure relief effect.

[0149] 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 roughly form a cylindrical shape. Each electrode typically includes an electrode body and tabs, which are full tabs. After the electrode assembly is formed, the tabs can be bent to gather and aggregate the ends furthest from the electrode body, forming a relatively dense stack. This reduces the gaps between the tab layers, facilitating welding between the tabs and the current collector. It also provides strong binding force to the entire electrode, ensuring the structural integrity of the electrode assembly and improving its charge / discharge performance. This strong mutual binding force between the tab layers, meaning the tabs themselves provide significant resistance to high-temperature, high-pressure media, creates a strong barrier. Therefore, the discharge of the high-temperature, high-pressure medium generated during thermal runaway of a cylindrical battery cell is restricted, resulting in a low discharge rate. This makes it difficult for the medium to spread to the pressure relief mechanism in a timely manner and be released outside the casing. Instead, it accumulates inside the cylindrical battery cell, leading to low efficiency and poor effectiveness of directional pressure relief through the mechanism. As thermal runaway continues, the internal pressure of the cylindrical battery cell increases continuously, posing a significant risk of explosion and thus reducing its reliability.

[0150] 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 plurality of bent segments distributed along the winding direction of the electrode assembly. A cutting groove is provided between any two adjacent segments along the winding direction of the electrode assembly, thereby reducing the density of the deposited layer formed by the portion of the electrode with the cutting groove. A pressure relief portion is provided at least at one end of the outer casing along a first direction. On a projection plane perpendicular to the first direction, the orthographic projection of the central hole and the orthographic projection of the bottom surface of the first groove of at least one cutting groove are both located within the orthographic projection of the pressure relief portion. This reduces the self-binding effect of the electrode on the portion of the pressure relief portion under the action of the cutting groove, thereby also reducing the mutual binding effect of the electrode segments on the portion of the pressure relief portion. During the thermal runaway of a cylindrical battery cell, the binding effect of the tabs on at least part of the pressure relief section is easily broken by the gas pressure. This allows at least part of the electrode sheet facing the pressure relief section to loosen under the pressure. This reduces the obstruction of the tabs to the high-temperature and high-pressure medium, facilitating the spread of the high-temperature and high-pressure medium towards the pressure relief mechanism and its release to the outside of the casing through the exhaust channel formed by the opening of the pressure relief section. This improves the discharge rate and efficiency of the high-temperature and high-pressure medium, enabling the cylindrical battery cell to achieve efficient directional pressure relief, thereby helping to improve the reliability of the cylindrical battery cell.

[0151] 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 is a 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] For ease of description, this application uses a vehicle as an example to illustrate the embodiments of the electrical device.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] In the cylindrical battery cell 10, the number of electrode components 1 can be one or more.

[0171] Among them, electrode assembly 1 can also be referred to as bare cell, winding body, etc.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] The outer shell 2 is cylindrical. Specifically, the shell 21 is cylindrical.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] The shell 21 and end cap 22 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0180] Please refer to Figures 3 through 11, and in conjunction with other accompanying figures. Figure 6 is an enlarged view of point B in Figure 4. Figure 7 is an enlarged view of point C in Figure 4, where the tab 112 and the electrode body 111 are separated by a dotted line. Figure 8 is a schematic diagram showing the unfolded electrode 11 of the cylindrical battery cell 10 provided in Figure 3, and Figure 9 is an enlarged view of point D in Figure 8. Figure 10 is a projection schematic diagram of the pressure relief section 22111 and the tab 112 of the cylindrical battery cell 10 provided in Figure 3, specifically a schematic diagram of the orthographic projection of the pressure relief section 22111 and the tab 112 on a projection plane perpendicular to the first direction Z. The projection of the tab 112 specifically refers to the projection of the root position of the tab 112, that is, the projection of the transition connection portion 1122 of the tab 112. In Figure 10, the outer contour lines of the pressure relief section 22111, the cut-off groove 102, the first notch groove 106, and the second notch groove 108 are all dashed lines. Figure 11 is an enlarged view of point E in Figure 10. The cylindrical battery cell 10 provided in this application embodiment includes an electrode assembly 1 and a housing 2. The housing 2 has a pressure relief section 22111 at at least one end along the first direction Z, and the pressure relief section 22111 is configured to at least partially open when pressure is released. At least a portion of the electrode assembly 1 is disposed within the housing 2. The electrode assembly 1 has a wound structure, and the electrode assembly 1 has a central hole 101 extending along the first direction Z. The electrode assembly 1 includes two electrode sheets 11 with opposite polarities. At least one electrode sheet 11 includes an electrode sheet body 111 and an electrode tab 112 arranged along the first direction Z. The electrode sheet 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. Both the tab 112 and the electrode body 111 are arranged around the outer periphery of the central hole 101. The tab 112 includes a plurality of segments 1121 distributed along the winding direction W of the electrode assembly 1, and the segments 1121 are bent. At least one segment 1121 of the plurality of segments is bent toward the central hole 101, and at least one segment 1121 of the plurality of segments is bent away from the central hole 101. Along the winding direction W of the electrode assembly 1, a cut-off groove 102 is provided between any two adjacent segments 1121. On a projection plane perpendicular to the first direction Z, the orthographic projection of the central hole 101 and the orthographic projection of the first groove bottom surface 103 of at least one cut-off groove 102 are both located within the orthographic projection of the pressure relief portion 22111.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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 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.

[0185] 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.

[0186] 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.

[0187] The electrode assembly 1 is provided with a central hole 101 extending along the first direction Z, which means that the central hole 101 passes through both ends of the electrode assembly 1 along the first direction Z.

[0188] 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.

[0189] When both the positive electrode 11a and the negative electrode 11b include an electrode body 111 and a 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; or, as shown in Figures 4 and 5, the positive electrode tab 112a and the negative electrode tab 112b are respectively disposed at both ends of the main body P along the first direction Z.

[0190] 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.

[0191] Among them, the electrode 112 may be, but is not limited to, a full electrode 112.

[0192] The electrode assembly 1 is a wound structure, meaning that the electrode 11 is wound to form a wound structure. Specifically, the electrode body 111 and the tab 112 of the electrode 11 are both wound, so that the electrode body 111 and the tab 112 are both wound structures, thereby making the electrode assembly 1 approximately cylindrical.

[0193] 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.

[0194] The cut-off groove 102 is a groove structure formed between two adjacent segments 1121 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.

[0195] It should be noted that when the electrode 11 is in a wound state to form a wound structure, the multiple segments 1121 of the tab 112 are sequentially distributed along the winding direction W of the electrode assembly 1, and the segments 1121 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 Figure 8, the multiple segments 1121 of the 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 tab 112, and the segments 1121 and the cutting grooves 102 are alternately distributed along the length direction X of the electrode 11.

[0196] At least one of the multiple segments 1121 is bent toward the direction of the central hole 101, meaning that at least one of the multiple segments 1121 is bent toward the direction of the central hole 101 relative to the electrode body 111. At least one of the multiple segments 1121 is bent away from the central hole 101, meaning that at least one of the multiple segments 1121 is bent away from the central hole 101 relative to the electrode body 111, as shown in Figure 7. Based on this, the end region of the tab 112 away from the electrode body 111 along the first direction Z can be bent, thereby forming a relatively dense stacked layer. Specifically, the multiple segments 1121 of the tab 112 are bent along the first direction Z away from the electrode body 111 to form a stacked layer.

[0197] 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.

[0198] 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.

[0199] In some possible designs, as shown in Figures 8 and 9, the tab 112 further includes a transition connection portion 1122, which is disposed between the piece 1121 and the electrode body 111 along the first direction Z. The first groove bottom surface 103 of the cut-off groove 102 is formed on the side edge of the transition connection portion 1122 away from the electrode body 111 along the first direction Z. Alternatively, in other possible designs, the tab 112 does not include the transition connection portion 1122, the piece 1121 contacts the electrode body 111 along the first direction Z, and the first groove bottom surface 103 of the cut-off groove 102 is formed on the side edge of the electrode body 111 near the piece 1121 along the first direction Z, such that the side edge of the piece 1121 near the electrode body 111 along the first direction Z forms the boundary between the electrode body 111 and the tab 112.

[0200] 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.

[0201] 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 projection of the first groove bottom surface 103 of all cut-off grooves 102 is located within the orthographic projection of the pressure relief part 22111; or, on the projection plane perpendicular to the first direction Z, the orthographic projection of the first groove bottom surface 103 of some cut-off grooves 102 is located within the orthographic projection of the pressure relief part 22111, and the orthographic projection of at least a portion of the first groove bottom surface 103 of some cut-off grooves 102 is located outside the orthographic projection of the pressure relief part 22111.

[0202] The cylindrical battery cell 10 provided in this application embodiment includes a plurality of bent segments 1121 on the tab 112 of the electrode assembly 1, distributed along the winding direction W of the electrode assembly 1. A cut-off groove 102 is provided between any two adjacent segments 1121 along the winding direction W of the electrode assembly 1, thereby reducing the density of the deposited layer formed by the portion of the tab 112 with the cut-off groove 102. A pressure relief portion 22111 is provided at least at one end of the outer casing 2 along the first direction Z. On a projection plane perpendicular to the first direction Z, the orthographic projection of the central hole 101 and the orthographic projection of the bottom surface 103 of the first groove of at least one cut-off groove 102 are both located within the orthographic projection of the pressure relief portion 22111. This reduces the self-binding effect of the tab 112 on the portion of the pressure relief portion 22111 under the action of the cut-off groove 102, thereby also reducing the mutual binding effect of the electrode 11 on the portion of the pressure relief portion 22111. Based on this, during the thermal runaway of the cylindrical battery cell 10, the binding effect of the tab 112 on at least part of the pressure relief section 22111 is easily broken under the action of air pressure, so that at least part of the electrode 11 on the pressure relief section 22111 is easily loosened under the action of air pressure. This can reduce the obstruction effect of the tab 112 on the high temperature and high pressure medium, and facilitate the spread of the high temperature and high pressure medium toward the pressure relief section 22111, and release it to the outside of the outer casing 2 through the exhaust channel formed by the opening of the pressure relief section 22111. This can improve the discharge rate and efficiency of the high temperature and high pressure medium, so that the cylindrical battery cell 10 can achieve a highly efficient directional pressure relief effect, thereby helping to improve the reliability of the cylindrical battery cell 10.

[0203] Furthermore, 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 will open under the action of air pressure and form an exhaust channel. The binding effect of the tab 112 on at least part of the pressure relief section 22111 is easily broken under the action of air pressure, so that at least part of the electrode 11 on the pressure relief section 22111 is easily loosened under the action of air pressure and released to the outside of the casing 2 through the exhaust channel formed by the opening of the pressure relief section 22111. The high temperature and high pressure medium generated inside the cylindrical battery cell 10 is also released along with the electrode 11. This can improve the pressure relief efficiency and pressure relief effect of the cylindrical battery cell 10.

[0204] It should also be noted that, on the projection plane perpendicular to the first direction Z, the orthographic projection of the central hole 101 and the orthographic projection of the bottom surface 103 of the first groove of at least one cut-off groove 102 are both located within the orthographic projection of the pressure relief portion 22111, so that the central hole 101 and the pressure relief portion 22111 are 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 directly opposite the pressure relief portion 22111 along the first direction Z, and the central hole 101 and the exhaust channel formed by the opening of the pressure relief portion 22111 are directly opposite and connected along the first direction Z. Thus, during the thermal runaway of the cylindrical battery cell 10, at least a portion of the electrode 11 facing the pressure relief portion 22111 can move toward the central hole 101 and loosen using the space of the central hole 101. That is, at least a portion of the electrode 11 adjacent to the central hole 101 can 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. Therefore, the central hole 101 facilitates the loosening of the electrode 11 under air pressure and allows the electrode 11 to be released to the outside of the outer casing 2, thereby facilitating exhaust and achieving a highly efficient directional pressure relief effect.

[0205] Specifically, the electrode 11 may have a winding start end 104 and a winding end end 105, which are respectively located 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, the winding end end 105 is located outside the winding start end 104, so that the winding start end 104 is closer to the center hole 101 than the winding end end 105. Based on this, after the pressure relief section 22111 is opened to form a venting channel, the winding start end 104 and the portion of the electrode 11 near the winding start end 104 will be vented to the outside of the housing 2 through the venting channel. In this way, at least a portion of the electrode 11 adjacent to the center hole 101 is loosened and vented through the venting channel, thereby improving the directional pressure relief efficiency and effect of the cylindrical battery cell 10.

[0206] In this configuration, on a projection plane perpendicular to the first direction Z, the orthographic projection of the winding starting end 104 lies within the orthographic projection of the pressure relief section 22111. Thus, during the process of the electrode 11 releasing pressure through the exhaust channel formed by the opening of the pressure relief section 22111, the space at the central hole 101 gradually increases as the electrode 11 releases pressure. This facilitates the discharge of high-temperature, high-pressure media through the central hole 101, improving the problem of low exhaust rate caused by the small aperture of the central hole 101, thereby achieving a highly efficient directional pressure relief effect.

[0207] It should also be noted that by forming a cut-off groove 102 on the tab 112, the connection strength between the tab layers of the tab 112 and the structural strength of the tab 112 can be reduced. This facilitates the breaking of at least part of the restraining effect of the tab 112 on the pressure relief section 22111 under the action of air pressure, allowing the electrode 11 to be released outside the casing 2 through the pressure relief section 22111, thereby improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0208] It should also be noted that the cutting groove 102 formed by the tab 112 makes the density of the stacked layer formed by bending the tab 112 relatively low. This makes it easier for the cutting groove 102 of the tab 112 to form a channel for venting, which facilitates the discharge of high temperature and high pressure medium, thereby improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0209] In some embodiments, the pressure relief section 22111 is configured to at least partially open and form an exhaust passage when pressure is released, through which at least a portion of the electrode 11 is released to the outside of the housing 2.

[0210] The exhaust passage refers to the passage formed by opening the pressure relief part 22111. The exhaust passage and the center hole 101 are opposite to and connected along the first direction Z.

[0211] With this configuration, 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 opens to form an exhaust channel. As the binding effect of the tab 112 is reduced, at least a portion of the electrode 11 can be loosened under the action of air pressure and released outside the casing 2 through the exhaust channel. This can improve the directional pressure relief effect of the cylindrical battery cell 10.

[0212] In some embodiments, please refer to FIG7 and other figures. At least one segment 1121 has a bent section 11211 at one end in a first direction Z. The bent section 11211 includes at least one first bent portion 112111 and at least one second bent portion 112112. The first bent portion 112111 is bent relative to the electrode body 111 in a direction close to the central hole 101, and the second bent portion 112112 is bent relative to the electrode body 111 in a direction away from the central hole 101.

[0213] The bent section 11211 is the part of the cut sheet 1121 that is bent relative to the electrode body 111.

[0214] The first bend 112111 and the second bend 112112 are two parts of the bend segment 11211. The first bend 112111 and the second bend 112112 are distributed approximately along the first direction Z.

[0215] In some possible designs, the cut-off piece 1121 may include a bent section 11211 and a straight section. Specifically, in the first direction Z, a straight section may connect the electrode body 111 and the bent section 11211, such that the end of the cut-off piece 1121 away from the electrode body 111 in the first direction Z can form a bent section 11211; in the first direction Z, a straight section may also connect adjacent first bent portions 112111; in the first direction Z, a straight section may also connect adjacent second bent portions 112112; and in the first direction Z, a straight section may also connect the first bent portion 112111 and the second bent portion 112112.

[0216] Based on this, the bending segment 11211 is bent relative to the electrode body 11, and the bending segment 11211 is also bent relative to the straight segment. The first bending portion 112111 is bent relative to the electrode body 11, and the first bending portion 112111 is also bent relative to the straight segment. The second bending portion 112112 is bent relative to the electrode body 11, and the second bending portion 112112 is also bent relative to the straight segment.

[0217] Alternatively, in some other possible designs, as shown in Figure 7, the section 1121 may also include a bent section 11211 without a straight section, and the bent section 11211 is directly connected to the electrode body 111.

[0218] At least one segment 1121 has a bent section 11211, and the bent section 11211 includes a first bent portion 112111 and a second bent portion 112112, so that the end region of the tab 112 away from the electrode body 111 along the first direction Z can be bent, thereby forming a relatively dense stacked layer. In this way, on the one hand, it is convenient to weld the segment 1121 of the tab 112 to the current collector 3 mentioned below. On the other hand, it gives the electrode 11 a strong binding effect, so that the electrode assembly 1 has a high degree of integrity, which facilitates the charge and discharge cycle of the cylindrical battery cell 10.

[0219] By forming a cut-off groove 102 between adjacent segments 1121 along the winding direction W, the high-temperature and high-pressure medium generated by the cylindrical battery cell 10 and the electrode 11 can be efficiently discharged through the pressure relief section 22111, so that the cylindrical battery cell 10 can achieve a highly efficient directional pressure relief effect, which can improve the problem of low pressure relief efficiency caused by the bending of the tab 112.

[0220] In some embodiments, please refer to FIG7, and in conjunction with other figures. The first bending portion 112111 and the second bending portion 112112 are both disposed with radial Y-bending along the electrode assembly 1.

[0221] Understandably, the first bending portion 112111 is bent in the radial direction Y toward the center hole 101 relative to the electrode body 111, and the second bending portion 112112 is bent in the radial direction Y away from the center hole 101 relative to the electrode body 111.

[0222] This design allows the tab 112 to bend effectively.

[0223] In some other embodiments, the first bending portion 112111 may be bent along a direction intersecting the radial Y, and the second bending portion 112112 may also be bent along a direction intersecting the radial Y.

[0224] In some embodiments, please refer to FIG7 and other figures. The first bend 112111 and the second bend 112112 are alternately arranged along the first direction Z.

[0225] This configuration allows the end region of the tab 112 that is away from the electrode body 111 along the first direction Z to be bent, thereby forming a relatively dense stacked layer.

[0226] In some embodiments, please refer to FIG7, and in conjunction with other figures. Each segment 1121 has the aforementioned bent segment 11211 at one end in the first direction Z.

[0227] Understandably, each segment 1121 has a first bend 112111 and a second bend 112112 formed thereon.

[0228] This configuration allows the end region of the tab 112 that is away from the electrode body 111 along the first direction Z to be bent, thereby forming a relatively dense stacked layer.

[0229] In some embodiments, please refer to Figures 4 to 9 together with other figures. Each of the two electrode plates 11 includes an electrode body 111 and an electrode tab 112. The electrode tabs 112 of the two electrode plates 11 are respectively disposed at both ends of the electrode assembly 1 along the first direction Z, that is, the electrode tab 112 of one electrode plate 11 is disposed at one end of the electrode assembly 1 along the first direction Z, and the electrode tab 112 of the other electrode plate 11 is disposed at the other end of the electrode assembly 1 along the first direction Z. The electrode tab 112 of each electrode plate 11 includes a plurality of segments 1121. On a projection plane perpendicular to the first direction Z, the orthographic projection of the first groove bottom surface 103 of at least one cut-off groove 102 on the electrode tab 112 of each electrode plate 11 is located within the orthographic projection of the pressure relief portion 22111.

[0230] 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 diaphragm 12, the first electrode body 111a, and the second electrode body 111b constitute the main body P of the electrode assembly 1. The positive electrode tab 112a and the negative electrode tab 112b are respectively located at both ends of the main body P along the first direction Z.

[0231] The positive electrode tab 112a includes multiple segments 1121 distributed along the winding direction W, and a cutting groove 102 is provided between any two adjacent segments 1121 along the winding direction W in the positive electrode tab 112a. The negative electrode tab 112b includes multiple segments 1121 distributed along the winding direction W, and a cutting groove 102 is provided between any two adjacent segments 1121 along the winding direction W in the negative electrode tab 112b. That is, both the positive electrode tab 112a and the negative electrode tab 112b are provided with cutting grooves 102.

[0232] In the positive electrode tab 112a, on the projection plane perpendicular to the first direction Z, the orthographic projection of the bottom surface 103 of at least one cut-off groove 102 is located within the orthographic projection of the pressure relief part 22111.

[0233] In the negative electrode tab 112b, on the projection plane perpendicular to the first direction Z, the orthographic projection of the bottom surface 103 of the first groove of at least one cut-off groove 102 is located within the orthographic projection of the pressure relief section 22111.

[0234] By adopting the above technical solution, the self-binding effect of the positive electrode tab 112a on the pressure relief section 22111 is weakened under the action of the cut-off groove 102, thereby weakening the mutual binding effect of the positive electrode piece 11a on the pressure relief section 22111. Furthermore, the self-binding effect of the negative electrode tab 112b on the pressure relief section 22111 is weakened, thereby weakening the mutual binding effect of the negative electrode piece 11b on the pressure relief section 22111. In this way, the self-binding effect of the positive electrode piece 11a, the self-binding effect of the negative electrode piece 11b, and the mutual binding effect between the positive and negative electrode pieces 11a and 11b can all be reduced. During the thermal runaway of the cylindrical battery cell 10, the binding effect of the positive electrode tab 112a on at least a portion of the pressure relief section 22111 and the binding effect of the negative electrode tab 112b on at least a portion of the pressure relief section 22111 can be broken under the action of air pressure. This allows at least a portion of the positive electrode 11a and at least a portion of the negative electrode 11b on the pressure relief section 22111 to be loosened under the action of air pressure and released to the outside of the outer casing 2 through the exhaust channel formed by the opening of the pressure relief section 22111. This arrangement facilitates the release of at least a portion of the electrode assembly 1 on the pressure relief section 22111 to the outside of the outer casing 2 under the action of air pressure, thereby achieving a highly efficient directional pressure relief effect and helping to improve the reliability of the cylindrical battery cell 10.

[0235] In some embodiments, please refer to Figures 12 and 13 together, and in conjunction with other figures. Figure 12 is a partially unfolded schematic diagram of the positive electrode 11a of the cylindrical battery cell 10 provided in Figure 3. In Figure 12, both the insulating layer 113 and the active material layer 1111 are shown in cross-section. Figure 13 is a partially unfolded schematic diagram of the negative electrode 11b of the cylindrical battery cell 10 provided in Figure 3. In Figure 13, 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.

[0236] 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.

[0237] In some embodiments, please refer to Figures 12 and 13 together, and in conjunction with other figures. The two electrodes 11 include a positive electrode 11a and a negative electrode 11b.

[0238] In some possible designs, as shown in Figure 12 and in conjunction with other figures, the tab 112 of the positive electrode 11a is not coated with an active material layer 1111.

[0239] 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.

[0240] 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.

[0241] In some possible designs, as shown in Figure 13 and in conjunction with other figures, the tab 112 of the negative electrode 11b is not coated with an active material layer 1111.

[0242] 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.

[0243] 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.

[0244] Since neither the positive electrode 11a nor the negative electrode 11b has an active material 1111 coated on the tab 112, during the process of cutting the tab 112 to form the cut piece 1121 and the cutting groove 102, only the tab 112 is cut and not the electrode body 111. Therefore, the part of the electrode 11 with the active material layer 1111 is not cut. As a result, the cutting groove 102 is formed in the part of the electrode 11 without the active material layer 1111. This can ensure the performance of the active material layer 1111 to a certain extent, thereby ensuring the performance of the electrode assembly 1 and the charge and discharge performance of the cylindrical battery cell 10.

[0245] In some embodiments, please refer to FIG12 and other figures. In the first direction Z, in the positive electrode 11a, the tab 112 is provided with an insulating layer 113 at the end region near the electrode body 111, and in the first direction Z, the cut-off piece 1121 is located on the side of the insulating layer 113 away from the electrode body 111.

[0246] 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.

[0247] As shown in Figure 12, 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.

[0248] In some possible designs, as shown in Figure 12, in the first direction Z, the segments 1121 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 1121 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.

[0249] 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.

[0250] In some embodiments, please refer to Figures 8, 9, 12, and 13 together with other figures. In Figures 9, 12, and 13, the transition connection portion 1122 and the segment 1121 of the electrode tab 112 are divided by dashed lines. The electrode tab 112 also includes the transition connection portion 1122, and the electrode body 111, the transition connection portion 1122, and the segment 1121 are arranged sequentially along the first direction Z. The transition connection portion 1122 and any two segments 1121 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 1122 used to connect the segment 1121.

[0251] Understandably, the electrode tab 112 includes a transition connection portion 1122 and a plurality of segments 1121, which are spaced apart along the winding direction W on the transition connection portion 1122. The electrode body 111 is connected to one side of the transition connection portion 1122 along the first direction Z, and the segments 1121 are connected to the other side of the transition connection portion 1122 along the first direction Z. Specifically, the current collector is connected to the side of the transition connection portion 1122 away from the segments 1121 along the first direction Z.

[0252] Understandably, the bottom surface 103 of the first groove is formed on one side edge of the transition connection portion 1122 along the first direction Z, close to the section 1121.

[0253] A transition connection portion 1122 connects the electrode body 111 and the cut-off piece 1121. On one hand, this allows the electrode body 111 and the cut-off piece 1121 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 1121, 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 1122 can block the cut-off piece 1121, thus isolating the cut-off piece 1121 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 1121 being bent and inserted into the main body P, reducing the risk of short circuits.

[0254] It should be noted that, referring to Figure 12 and other accompanying figures, in the positive electrode 11a, an insulating layer 113 is disposed on at least a portion of the transition connection portion 1122. In some possible designs, as shown in Figure 12, the insulating layer 113 is disposed on a portion of the transition connection portion 1122 such that the insulating layer 113 and the segment 1121 are spaced apart along the first direction Z. Alternatively, in other possible designs, the insulating layer 113 completely covers the transition connection portion 1122, 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 1121 approaching the transition connection portion 1122 along the first direction Z.

[0255] In some embodiments, please refer to Figures 8 and 9 together, and in conjunction with other figures. The dimension of one side edge of the piece 1121 used to connect the transition connection portion 1122 in the winding direction W of the electrode assembly 1 is L1, and the sum of the dimensions of the transition connection portion 1122 and the piece 1121 in the first direction Z is L2, where 0.01≤L2 / L1≤0.3.

[0256] The section 1121 used to connect one side edge of the transition connection portion 1122 refers to the side edge of the section 1121 along the first direction Z that is close to the electrode body 111, that is, the edge of the section 1121 at the boundary between the section 1121 and the transition connection portion 1122. The boundary between the section 1121 and the transition connection portion 1122 is mainly based on the position of the bottom surface 103 of the first groove, which can be specifically referred to in Figures 9, 12 and 13 for dividing the transition connection portion 1122 and the section 1121. It can be understood that the side edge of the section 1121 used to connect the transition connection portion 1122 is collinearly connected with the bottom surface 103 of the first groove.

[0257] The dimension of the side edge of the piece 1121 used to connect the transition connection portion 1122 in the winding direction W of the electrode assembly 1 refers to the maximum dimension of the piece 1121 in the winding direction W. It also refers to the dimension of the side edge of the piece 1121 used to connect the transition connection portion 1122 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 1121 in the length direction X of the electrode 11 when the electrode 11 is in the unfolded state.

[0258] The sum of the dimensions of the transition connection 1122 and the segment 1121 in the first direction Z refers to the sum of the dimensions of the transition connection 1122 and the segment 1121 in the first direction Z before the segment 1121 is bent or when the segment 1121 is in the unfolded state, which is the maximum dimension of the tab 112 in the first direction Z.

[0259] 0.01≤L2 / L1≤0.3, where L2 / L1 can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, etc.

[0260] This configuration allows the cut piece 1121 to have a larger size in the winding direction W, which facilitates the winding of the cut piece 1121 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.

[0261] In some embodiments, please refer to Figures 8 and 9 together, and in conjunction with other figures. The dimension of the transition connection portion 1122 in the first direction Z is L3, 0.1mm≤L3≤2mm.

[0262] The dimension of the transition connection portion 1122 in the first direction Z refers to the distance between the edge of the segment 1121 near the electrode body 111 and the edge of the electrode body 111 near the segment 1121 in the first direction Z.

[0263] L3 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.

[0264] With this configuration, the transition connection portion 1122 has a suitable width in the first direction Z to block the cut-off groove 102, thus improving the problem of the cut-off piece 1121 bending and inserting into the main body portion P.

[0265] In some embodiments, please refer to Figures 3, 4, 6, 10, and 11 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.

[0266] 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.

[0267] 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.

[0268] 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, 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 the pressure relief section 22111 to open and form an exhaust passage.

[0269] 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 release of the electrode 11 to the outside of the outer casing 2 through the pressure relief section 22111 under the action of air pressure.

[0270] 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.

[0271] 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.

[0272] 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.

[0273] 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.

[0274] The pressure relief mechanism 2211 and the first wall 2212 can constitute the aforementioned first end wall 221.

[0275] 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.

[0276] 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.

[0277] 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.

[0278] 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.

[0279] In some embodiments, please refer to Figures 4, 6, 10, and 11 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.

[0280] 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.

[0281] In some embodiments, please refer to Figures 6, 8, 10, 11, 14 to 16 together, and in conjunction with other figures. Figure 14 is an enlarged view of point F in Figure 4, Figure 15 is an enlarged view of point G in Figure 8, and Figure 16 is an enlarged view of point H in Figure 8. In Figures 15 and 16, the section 1121 and the transition connection 1122 are separated by a dashed line. 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. 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.

[0282] Specifically, the winding start end 104 and the winding end end 105 are respectively located 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.

[0283] In the radial direction Y, the winding end 105 is located outside the winding start end 104, so that the winding start end 104 is closer to the center hole 101 relative to the winding end 105.

[0284] It should be noted that both the positive electrode 11a and the negative electrode 11b have a winding start end 104 and a winding end end 105.

[0285] In some embodiments, please refer to Figures 8, 10, 14, and 15 together with other figures. The tab 112 has a first notch 106 near the winding start end 104. The first notch 106 penetrates the winding start end 104 along the winding direction W of the electrode assembly 1 and penetrates the end face of the tab 112 opposite to the electrode body 111. The tab 112 has a winding start section 11221 located at one end of the first notch 106 near the electrode body 111. In the first direction Z, the tab 1121 extends beyond the bottom surface 107 of the second groove of the first notch 106 in a direction away from the electrode body 111. The bottom surface 107 of the second groove is the end face of the winding start section 11221 opposite to the electrode body 111.

[0286] Understandably, in the first direction Z, the cut piece 1121 extends beyond the winding start section 11221, and the cut piece 1121 and the winding start section 11221 surround and form the first notch 106.

[0287] The second groove bottom surface 107 of the first notch groove 106 refers to the groove bottom wall of the first notch groove 106 along the first direction Z, specifically the wall surface of the first notch groove 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 starting section 11221 along the first direction Z away from the electrode body 111.

[0288] Specifically, before the cut piece 1121 is bent or in an unfolded state, the first notch 106 penetrates the end face of the electrode tab 112 away from the electrode body 111 along the first direction Z.

[0289] Wherein, when the tab 112 includes a transition connection portion 1122, the winding start segment 11221 is a part of the transition connection portion 1122. Understandably, the transition connection portion 1122 may include a winding intermediate segment 11223 and a winding start segment 11221, the winding start segment 11221 and the winding intermediate segment 11223 being connected sequentially along the winding direction W of the electrode assembly 1, both the winding intermediate segment 11223 and the winding start segment 11221 being disposed on the side edge of the electrode body 111 along the first direction Z near the tab 112, and the winding intermediate segment 11223 being connected between the electrode body 111 and the cut-off piece 1121 along the first direction Z. When the tab 112 does not include the transition connection portion 1122, the stub 1121 and the winding start section 11221 are both located on the edge of the electrode body 111 along the first direction Z near the tab 112. The winding start section 11221 and the stub 1121 are distributed sequentially along the winding direction W of the electrode assembly 1. Before the stub 1121 is bent, the size of the stub 1121 along the first direction Z is larger than the size of the winding start section 11221 along the first direction Z.

[0290] By adopting the above technical solution, the first notch 106 and the cut-off groove 102 are spaced apart along the winding direction W. The first notch 106 penetrates the winding start end 104, and 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 also allows the orthographic projection of the bottom surface 107 of the second notch 106 to lie within the orthographic projection of the pressure relief section 22111, thereby ensuring that the orthographic projection of the winding start segment 11221 lies within the orthographic projection of the pressure relief section 22111. In this way, the binding effect of the portion of the electrode 11 with the first notch 106 is reduced, facilitating the release of pressure from the electrode 11 to the outside of the casing 2 through the pressure relief section 22111 during thermal runaway, thereby improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0291] In some embodiments, please refer to Figures 4, 6, 10, and 14 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.

[0292] In some embodiments, please refer to Figures 4, 6, 10, 14, and 15 together, and in conjunction with other figures. On a projection plane perpendicular to the first direction Z, the orthographic projection of the winding start segment 11221 lies within the orthographic projection of the pressure relief portion 22111. The current collecting member 3 is welded to the segment 1121, but not to the winding start segment 11221.

[0293] By welding the current collector 3 to the section 1121 but not to the winding start section 11221, the binding effect of the portion of the electrode 11 with the first notch 106 is lower. This makes it easier for the portion of the electrode 11 with the first notch 106 to be released through the pressure relief section 22111 under the action of air pressure during the thermal runaway of the cylindrical battery cell 10, thereby improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0294] In some embodiments, please refer to Figures 4, 6, 10, and 16 together with other figures. The tab 112 has a second notch 108 near the winding end 105. The second notch 108 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 away from the electrode body 111. The tab 112 has a winding end segment 11222, located at the end of the second notch 108 near the electrode body 111. In the first direction Z, the cut piece 1121 extends beyond the bottom surface 109 of the third groove of the second notch 108 in a direction away from the electrode body 111. The bottom surface 109 of the third groove is the end face of the winding end segment 11222 facing away from the electrode body 111.

[0295] Understandably, in the first direction Z, the cut piece 1121 extends beyond the winding end section 11222, and the cut piece 1121 and the winding end section 11222 surround to form a second notch 108.

[0296] The third groove bottom surface 109 of the second notch groove 108 refers to the groove bottom wall of the second notch groove 108 along the first direction Z, specifically the wall surface of the second notch groove 108 along the first direction Z that is close to the electrode body 111. The third groove bottom surface 109 is formed on the edge of the winding end section 11222 along the first direction Z away from the electrode body 111.

[0297] Specifically, before the cut piece 1121 is bent or in an unfolded state, the second notch 108 penetrates the end face of the tab 112 away from the electrode body 111 along the first direction Z.

[0298] Wherein, when the tab 112 includes a transition connection portion 1122, the winding end segment 11222 is a part of the transition connection portion 1122. Understandably, the transition connection portion 1122 may include a winding middle segment 11223 and a winding end segment 11222, which are sequentially connected along the winding direction W of the electrode assembly 1. Both the winding middle segment 11223 and the winding end segment 11222 are located on the edge of the electrode body 111 along the first direction Z near the tab 112, and the winding middle segment 11223 is connected along the first direction Z between the electrode body 111 and the cut-off piece 1121. Specifically, along the winding direction W, the winding middle segment 11223 is connected between the winding start segment 11221 and the winding end segment 11222.

[0299] When the tab 112 does not include the transition connection portion 1122, the stub 1121 and the winding end segment 11222 are both disposed on the edge of the electrode body 111 along the first direction Z near the tab 112. The winding end segment 11222 and the stub 1121 are distributed sequentially along the winding direction W of the electrode assembly 1, and the size of the stub 1121 along the first direction Z is larger than the size of the winding end segment 11222 along the first direction Z. Specifically, along the winding direction W, all stubs 1121 are disposed between the winding start segment 11221 and the winding end segment 11222.

[0300] This configuration allows the second notch 108 to form a channel for venting. Furthermore, the binding effect of the portion of the electrode 11 with the second notch 108 (which may, but is not limited to, the winding end section 11222 described below) is reduced, making it easier for this portion of the electrode 11 to loosen or even eject from the pressure relief section 22111 during thermal runaway. This, in turn, facilitates improved directional pressure relief efficiency of the cylindrical battery cell 10.

[0301] In some embodiments, please refer to Figures 4, 6, 10, and 16 together with other figures. The current collector 3 is welded to the section 1121 but not to the winding end section 11222.

[0302] By welding the current collector 3 to the section 1121 but not to the winding end section 11222, the binding effect of the portion of the electrode 11 with the second notch 108 is reduced, making it easier for the portion of the electrode 11 with the second notch 108 to loosen or even be ejected from the pressure relief section 22111 during thermal runaway. This facilitates improving the directional pressure relief efficiency of the cylindrical battery cell 10.

[0303] In some embodiments, please refer to Figures 4, 6, 7, 17, and 18 together with other accompanying drawings. Figure 17 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 17, 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 18 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 18, the structure shown by the cross-sectional line is the first welded portion 4, and the first arc M3 and the second arc M4 are both dashed lines. 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 segment 1121 of the tab 112 to form the first welded part 4.

[0304] 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.

[0305] Among them, the current collection component 3 may be, but is not limited to, a current collection disk.

[0306] The current transmission terminal 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.

[0307] Specifically, the current collector 3 and the tab 112 are arranged generally along the first direction Z. That is, the electrode assembly 1 has a current collector 3 at at least one end along the first direction Z, and the current collector 3 is generally disposed between the 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 current collectors 3 at both ends 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.

[0308] 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 tabs 112 at each end. Alternatively, the current collector 3 is provided at one end of electrode assembly 1 along the first direction Z.

[0309] The first weld 4 refers to the weld mark formed by welding the current collector 3 and the electrode lug 112.

[0310] 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, as shown in Figure 18, 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.

[0311] By welding the current collector 3 and the tab 112, the current collector 3 can perform current collection on the electrode assembly 1, which facilitates the electrical connection of the current transmission end of the cylindrical battery cell 10 to the electrode assembly 1, thereby facilitating the use of the cylindrical battery cell 10.

[0312] 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.

[0313] In some embodiments, please refer to Figures 6, 7, 11, 17, and 18 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 welded portion 4 have a first projection endpoint M1 and a second projection endpoint M2, respectively. The first projection endpoint M1 is closer to the central hole 101 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 central hole 101, and the second arc line M4, which passes through the second projection endpoint M2 and surrounds the central hole 101, 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.

[0314] 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 orthographic projection of the first welding part 4 along the radial direction Y. The first arc line M3 passes through the first projection endpoint M1, and the second arc line M4 passes through the second projection endpoint M2. The first arc line M3 and the second arc line M4 are both arranged around the outer periphery of the central hole 101. The first arc line M3 and the second arc line M4 are arranged at intervals along the radial direction Y, and the second arc line M4 surrounds the outer periphery of the first arc line M3, so that the first arc line M3 and the second arc line M4 form a first transverse region M5 at intervals along the radial direction Y. The first transverse region M5 is approximately annular.

[0315] 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.

[0316] In this design, both the first arc M3 and the second arc M4 are arc-shaped. As an example, as shown in Figures 17 and 18, both the first arc M3 and the second arc M4 are circular.

[0317] In the first group of slots, the orthographic projection of the first slot bottom surface 103 of all cut-off slots 102 is located within the first transverse region M5. Specifically, on the projection plane perpendicular to the first direction Z, the orthographic projection of the first slot bottom surface 103 of each cut-off slot 102 is substantially located within the first transverse region M5. In other words, all cut-off slots 102 whose orthographic projections of the first slot bottom surface 103 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 is understood that the portion of the tab 112 where the first welding portion 4 is formed is provided with the aforementioned cut-off slot 102.

[0318] 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.

[0319] In some possible designs, please refer to Figures 10 and 11 together, and in conjunction with other accompanying drawings. In the first set of slots, the number of turns of a single cut-off slot 102 is ≤3.

[0320] 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.

[0321] 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.

[0322] As an example, as shown in Figure 11, the cut-off groove 102 shown in Figure 13 has less than one turn.

[0323] In some possible designs, please refer to Figures 10 and 11 together, and in conjunction with other figures. 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.

[0324] Understandably, on the projection plane perpendicular to the first direction Z, the number of continuously opposite and connected cut-off slots 102 along the radial direction Y is ≤3. On the projection plane perpendicular to the first direction Z, the number of continuously opposite and connected cut-off slots 102 along the radial direction Y can be 3 or 2; or, any two cut-off slots 102 are not opposite and connected along the radial direction Y.

[0325] As an example, as shown in Figure 11, the number of radially opposite and connected cut-off slots 102 can be two.

[0326] By adopting the above technical solution, based on the provision of the cut-off groove 102 in the portion of the tab 112 where the first welding part 4 is formed, the deposited layer formed by bending in the portion of the tab 112 where the first welding part 4 is formed will not be too thin due to the setting of the cut-off groove 102. This allows the portion of the tab 112 where the first welding part 4 is formed to bear the welding penetration of the current collector 3 and the tab 112, which can improve 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 tab 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 tab 112, and reduce the risk of short circuit.

[0327] In some embodiments, please refer to Figures 4 and 19 together, and in conjunction with other figures. Figure 19 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 19, 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 cylindrical battery cell 10 also includes electrode terminals 5, which are fixed to the housing 2. The electrode terminals 5 are welded to the current collector 3 to form a second welded portion 6.

[0328] Electrode terminal 5 refers to a component with conductive properties. Electrode terminal 5 serves as the current transmission terminal of a single battery cell for transmitting current. Electrode terminal 5 may be, but is not limited to, a terminal post.

[0329] The electrode terminal 5 can be welded to the current collector 3 welded to the positive electrode tab 112a, or it can be welded to the current collector 3 welded to the negative electrode tab 112b.

[0330] 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. The electrode assembly 1 is provided with a current collector 3 at the end of 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.

[0331] 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.

[0332] Electrode terminals 5 are disposed on the outer casing 2. Specifically, as shown in Figure 4, electrode terminals 5 can be disposed on the housing 21 of the outer casing 2. Electrode terminals 5 can also be disposed on the end cap 22 of the outer casing 2.

[0333] 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.

[0334] Electrode terminal 5 is welded to current collector 3, and current collector 3 is welded to electrode tab 112, so that electrode terminal 5 can be electrically connected to electrode assembly 1.

[0335] The second welding part 6 refers to the weld mark formed by welding the electrode terminal 5 and the current collector 3.

[0336] As an example, as shown in Figure 19, 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, 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.

[0337] This configuration allows for electrical connection between electrode terminal 5 and electrode assembly 1.

[0338] In some embodiments, please refer to Figures 4 and 19 together, and in conjunction with other figures. On the projection plane perpendicular to the first direction Z, the two ends of the orthographic projection of the second welded part 6 have a third projection endpoint N1 and a fourth projection endpoint N2, respectively. The fourth projection endpoint N2 is closer to the central hole 101 than the third projection endpoint N1. The area between the third arc line N3 that passes through the third projection endpoint N1 and surrounds the central hole 101 and the fourth arc line N4 that passes through the fourth projection endpoint N2 and surrounds the central hole 101 is the second transverse region N5. At least a portion of the cut-off grooves 102 form a second set of grooves, and 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.

[0339] 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 central hole 101. The third arc N3 and the fourth arc N4 are arranged at intervals 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 at intervals along the radial Y. The second transverse region N5 is approximately annular.

[0340] 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.

[0341] In this design, both the third arc N3 and the fourth arc N4 are arc-shaped. As an example, as shown in Figure 19, both the third arc N3 and the fourth arc N4 are circular.

[0342] In the second group of slots, the orthographic projection of the first slot bottom surface 103 of all cut-off slots 102 lies within the second transverse region N5. Specifically, on the projection plane perpendicular to the first direction Z, the orthographic projection of the first slot bottom surface 103 of each cut-off slot 102 is substantially within the second transverse region N5. In other words, all cut-off slots 102 whose orthographic projections of the first slot bottom surface 103 are substantially within the second transverse region N5 on the projection plane perpendicular to the first direction Z constitute the second group of slots. It is understood that the portion of the tab 112 where the second welding portion 6 is formed is provided with the aforementioned cut-off slot 102.

[0343] 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.

[0344] 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 outside the second welding portion 6. Based on this, in the radial Y direction, the first set of grooves is located outside the second set of grooves.

[0345] In some possible designs, please refer to Figures 4, 10, 11, 18, and 19, in conjunction with other accompanying drawings. In the second set of slots, the number of turns of a single cut-off slot 102 is ≤3.

[0346] 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.

[0347] 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.

[0348] As an example, as shown in Figure 11, the cut-off groove 102 shown in Figure 13 has less than one turn.

[0349] In some possible designs, please refer to Figures 4, 10, 11, 18, and 19 together with other accompanying drawings. In the second set of slots, the number of cut-off slots 102 that are opposite each other and connected along the radial Y direction of the electrode assembly 1 is ≤3.

[0350] 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.

[0351] As an example, as shown in Figure 11, the number of radially opposite and connected cut-off slots 102 can be two.

[0352] By adopting the above technical solution, based on the provision of the cut-off groove 102 in the portion of the tab 112 where the second welding part 6 is formed, the deposited layer formed by bending in the portion of the tab 112 where the second welding part 6 is formed will not be too thin due to the setting of the cut-off groove 102. This allows the portion of the tab 112 where the second welding part 6 is formed to bear the welding penetration of the current collector 3 and the electrode terminal 5, which can improve 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. 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.

[0353] In some embodiments, please refer to Figures 4 and 14 together, 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 notch groove 106.

[0354] By providing the first welding portion 4 on the outer side of the first notch 106 in the radial Y direction of the electrode assembly 1, the deposited layer formed by bending the portion of the tab 112 with the first welding portion 4 will not be too thin due to the setting of the first notch 106. This allows the portion of the tab 112 with the first welding portion 4 to bear the welding penetration of the current collector 3 and the tab 112, thereby 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 tab 112.

[0355] In some embodiments, please refer to Figures 4 and 14 together, and in conjunction with other figures. In the radial Y direction of the electrode assembly 1, the second welding portion 6 is located outside the first notch groove 106.

[0356] By providing the second welding portion 6 on the outer side of the first notch 106 in the radial Y direction of the electrode assembly 1, the deposited layer formed by bending the portion of the tab 112 with the second welding portion 6 will not be too thin due to the setting of the first notch 106. This allows the portion of the tab 112 with the second welding portion 6 to bear the welding penetration of the current collector 3 and the electrode terminal 5, thereby 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.

[0357] 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.

[0358] In some embodiments, please refer to Figures 4, 6, and 14 together, and in conjunction with other figures. In the radial Y direction of the electrode assembly 1, the second notch 108 is located outside the first weld portion 4.

[0359] By positioning the second notch 108 on the radial Y direction of the electrode assembly 1 outside the first weld portion 4, the stacked layer formed by bending the portion of the tab 112 with the first weld portion 4 will not be too thin due to the setting of the second notch 108. This allows the portion of the tab 112 with the first weld portion 4 to bear the weld penetration depth of the current collector 3 and the tab 112, thereby improving the problem of laser penetration of the tab 112 and burn to the diaphragm 12 during the welding process of the current collector 3 and the tab 112.

[0360] In some embodiments, please refer to Figures 4 and 14 together, and in conjunction with other figures. In the radial Y direction of the electrode assembly 1, the second notch 108 is located outside the second weld portion 6.

[0361] By positioning the second notch 108 on the outer side of the second weld portion 6 in the radial direction Y of the electrode assembly 1, the deposited layer formed by bending the portion of the tab 112 where the second weld portion 6 is formed will not be too thin due to the setting of the second notch 108. This allows the portion of the tab 112 where the second weld portion 6 is formed to bear the welding penetration of the current collector 3 and the electrode terminal 5, thereby 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.

[0362] 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.

[0363] In some embodiments, please refer to Figures 4, 6, and 14 together, and in conjunction with other figures. Both electrode plates 11 include an electrode body 111 and an electrode tab 112. The electrode tab 112 of one electrode plate 11 is a first electrode tab, and the electrode tab 112 of the other electrode plate 11 is a second electrode tab. The first electrode tab and the second electrode tab are respectively located at both ends of the electrode assembly 1 along the first direction Z. In the first direction Z, both ends of the electrode assembly 1 are provided with current collectors 3, and the current collectors 3 located 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 section 1121 of the first electrode tab, and the second current collector 3b is welded to the section 1121 of the second electrode tab.

[0364] The first electrode can be a positive electrode 112a, and the second electrode can be a negative electrode 112b. Alternatively, the first electrode can be a negative electrode 112b, and the second electrode can be a positive electrode 112a.

[0365] The first current collector 3a is welded to the segment 1121 of the first electrode tab to form the first welded portion 4. The second current collector 3b is welded to the segment 1121 of the second electrode tab to form the first welded portion 4. Understandably, both the first electrode tab and the second electrode tab have the first welded portion 4 formed thereon.

[0366] 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.

[0367] In some embodiments, please refer to Figures 4, 6, and 14 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 current collector 3a is electrically connected to the electrode terminal 5, and a second current collector 3b is electrically connected to the side wall 212.

[0368] 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.

[0369] 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.

[0370] The second end wall 211 may be at least a portion of the end cap 22; or, as shown in Figures 4 and 14, the second end wall 211 may be a portion of the housing 21.

[0371] As shown in Figures 4, 6 and 14, the sidewall 212 is part of the shell 21 and has electrical conductivity.

[0372] 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.

[0373] 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.

[0374] 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. Alternatively, other intermediate components can be provided between the second current collector 3b and the side wall 212 to achieve an electrical connection; as an example, this intermediate component is a first end wall 221, the second current collector 3b and the first end wall 2212 of the first end wall 221 are welded, and the first end wall 221 and the side wall 212 are welded.

[0375] 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.

[0376] 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.

[0377] 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.

[0378] 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.

[0379] In some embodiments, please refer to Figures 4 and 6 together, and in conjunction with other figures. The second current collector 3b is welded to the first end wall 221, and the side wall 212 is electrically connected to the first end wall 221.

[0380] 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.

[0381] Specifically, the first wall 2212 of the first end wall 221 is welded to the second current collector 3b, and the first wall 2212 of the first end wall 221 is welded to the side wall 212.

[0382] This configuration allows the second current collector 3b to be indirectly electrically connected to the side wall 212 via the first end wall 221.

[0383] 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.

[0384] 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.

[0385] 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.

[0386] This configuration allows the second current collector 3b to be directly electrically connected to the side wall 212.

[0387] In some embodiments, please refer to Figures 4, 5, and 14 together, and in conjunction with other accompanying drawings. The first electrode tab is a positive electrode tab 112a, and the second electrode tab is a negative electrode tab 112b.

[0388] 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.

[0389] As an example, both the side wall 212 and the first end wall 221 can be made of steel.

[0390] 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.

[0391] In some embodiments, please refer to Figures 4 and 6 together, and in conjunction with other figures. A pressure relief portion 22111 is provided on the first end wall 221.

[0392] Understandably, the first end wall 221 includes the aforementioned first wall 2212 and pressure relief mechanism 2211, the pressure relief mechanism 2211 being connected to the first wall 2212, and the pressure relief mechanism 2211 including 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.

[0393] 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.

[0394] 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 mechanism 2211 of the cylindrical battery cell 10 shown in Figure 3. Specifically, it is a schematic diagram of the orthographic projection of the pressure relief mechanism 2211 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 mechanism 2211 is shown as a dashed line. The current collector 3 has a vent hole 301 extending along the first direction Z, which is opposite to and communicates with the central hole 101 along the first direction Z. The current collector 3 also has a plurality of guide portions 32, which are spaced apart around the outer periphery of the vent hole 301.

[0395] The flow collecting component 3 is provided with an exhaust through hole 301 extending along the first direction Z, which means that the exhaust through hole 301 penetrates the flow collecting component 3 along the first direction Z.

[0396] 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 through hole 301, thereby increasing the size of the exhaust through hole 301. Specifically, the collector member 3 can be split along the guide portion 32 to expand the exhaust area of ​​the exhaust through hole 301.

[0397] Multiple guide sections 32 are spaced apart along the circumferential direction E and together surround the outer periphery of the exhaust port 301.

[0398] 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.

[0399] 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.

[0400] In some embodiments, please refer to FIG4, and in conjunction with other figures. The vent 301 and the pressure relief portion 22111 are disposed opposite each other along the first direction Z.

[0401] Based on this, when the pressure value inside the outer casing 2 reaches the threshold, the weak part 22112 is disconnected so that the pressure relief part 22111 is opened to form an exhaust channel. The central hole 101, the exhaust through hole 301 and the exhaust channel are connected in sequence along the first direction Z, which facilitates exhaust and helps to improve the directional pressure relief efficiency.

[0402] In some embodiments, please refer to FIG4, 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.

[0403] 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.

[0404] The pressure relief mechanism 2211 includes a pressure relief part 22111 and a first groove 201, which surrounds the outer periphery of the pressure relief part 22111. On a projection plane perpendicular to the first direction Z, the outer contour of the orthographic projection of the pressure relief part 22111 refers to the inner contour of the orthographic projection of the first groove 201, which is the connection position between the orthographic projection of the pressure relief part 22111 and the orthographic projection of the first groove 201.

[0405] 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.

[0406] 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.

[0407] In some embodiments, the guide portion 32 includes a through hole that penetrates the current collecting member 3 along a first direction Z.

[0408] 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.

[0409] 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.

[0410] The current collector 31 can be welded to the tab 112 to form the first welded part 4 mentioned above.

[0411] The current collector 31 can be welded to the electrode terminal 5 to form the second welded part 6 mentioned above.

[0412] 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.

[0413] 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 flip towards the pressure relief part 22111 during thermal runaway, thereby improving the directional pressure relief effect of the cylindrical battery cell 10.

[0414] 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.

[0415] 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.

[0416] 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.

[0417] 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.

[0418] In some embodiments, please refer to FIG10, and in conjunction with other figures. Among the plurality of segments 1121 of the tab 112, the segment 1121 closest to the winding end 105 is wound at least one turn.

[0419] As an example, as shown in Figure 10, among the multiple segments 1121 of the tab 112, the segment 1121 closest to the winding end 105 is wound multiple times.

[0420] By winding the piece 1121 closest to the winding end 105 at least once, the piece 1121 closest to the winding end 105 can achieve a better wrapping effect on the other pieces 1121. This can improve the problem of internal short circuit caused by the piece 1121 turning outward and inserting into the main body P, thereby reducing the risk of short circuit.

[0421] In some embodiments, please refer to FIG8, and in conjunction with other figures. The tab 112 is provided with a plurality of cut-off grooves 102, and the cut-off grooves 102 and the cut pieces 1121 are arranged alternately in the winding direction W of the electrode assembly 1.

[0422] Understandably, the number of slices 1121 is at least 3.

[0423] Understandably, multiple cutting grooves 102 are spaced apart on the tab 112 along the winding direction W, and multiple segments 1121 are sequentially arranged on the tab 112 along the winding direction W, with each cutting groove 102 and each segment 1121 arranged alternately along the winding direction W.

[0424] By forming multiple cut-off grooves 102 on the tab 112, a larger removal ratio can be achieved, allowing the portion of the electrode 11 with the cut-off grooves 102 to be released through the pressure relief section 22111 during thermal runaway, thus achieving a highly efficient directional pressure relief effect. Furthermore, the deposited layer formed by bending the portion of the tab 112 with the cut-off grooves 102 is not too thin, effectively blocking the laser generated during welding, thereby providing protection for the diaphragm 12. In addition, the multiple cut-off grooves 102 allow for adjustments to the tab 112 removal operation based on actual needs, making the process of forming the cut-off grooves 102 on the tab 112 highly flexible.

[0425] In some embodiments, as shown in FIG8 and in conjunction with other figures, the plurality of cut-off slots 102 of the tab 112 may have the same size. For example, the cut-off slots 102 may have the same size along the winding direction W. Alternatively, at least two of the plurality of cut-off slots 102 of the tab 112 may have different sizes.

[0426] 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 tab 112 may be identical. Alternatively, at least two of the plurality of cut-off grooves 102 in the tab 112 may have different shapes.

[0427] In some embodiments, as shown in FIG8 and in conjunction with other figures, at least two of the multiple segments 1121 of the tab 112 may have different dimensions. For example, as shown in FIG8, the two segments 102 may have different dimensions along the winding direction W. Alternatively, the multiple segments 1121 of the tab 112 may have the same dimension.

[0428] As shown in Figure 8, the shapes of the multiple segments 1121 of the tab 112 can be the same. Alternatively, at least two of the multiple segments 1121 of the tab 112 can have different shapes.

[0429] In some embodiments, please refer to Figures 8 and 9 together, and in conjunction with other figures. In the first direction Z, the size of the slit 1121 along the winding direction W of the electrode assembly 1 tends to decrease in the direction away from the electrode body 111.

[0430] In the first direction Z, the segment 1121 can be gradually reduced in size along one side of the winding direction W of the electrode assembly 1, moving away from the electrode body 111; or, in the first direction Z, the segment 1121 can be gradually reduced in size along both sides of the winding direction W of the electrode assembly 1, moving away from the electrode body 111, so that when the electrode 11 is in the unfolded state, the segment 1121 is approximately trapezoidal. Based on this, in the first direction Z, the size of the segment 1121 gradually decreases in size along the winding direction W, moving away from the electrode body 111.

[0431] 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.

[0432] By gradually reducing the size of the cut-off piece 1121 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 1121 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.

[0433] 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%].

[0434] 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.

[0435] 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.

[0436] 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.

[0437] 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.

[0438] 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.

[0439] 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.

[0440] As one embodiment of this application, as shown in Figures 4 to 11, the cylindrical battery cell 10 includes a housing 2 and an electrode assembly 1 disposed within the housing 2. A pressure relief portion 22111 is provided at one end of the housing 2 along a first direction Z, and the pressure relief portion 22111 is configured to at least partially open during pressure relief. 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 electrode 11a and the negative electrode 11b 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 disposed at both ends of the electrode body 111 along the first direction Z. The tab 112 includes a plurality of bent segments 1121 distributed along the winding direction W of the electrode assembly 1. Each segment 1121 has a bent section 11211 at one end along the first direction Z. The bent section 11211 includes a first bent portion 112111 and a second bent portion 112112 alternately arranged along the first direction Z. The first bent portion 112111 is bent radially Y relative to the electrode body 111 toward the center hole 101, and the second bent portion 112112 is bent radially Y relative to the electrode body 111 toward the direction away from the center hole 101. A cut-off groove 102 is provided between any two adjacent segments 1121 along the winding direction W of the electrode assembly 1. On a projection plane perpendicular to the first direction Z, the orthographic projection of the center hole 101 and the orthographic projection of the bottom surface 103 of the first groove of at least one cut-off groove 102 are both located within the orthographic projection of the pressure relief portion 22111. Furthermore, 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.

[0441] 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 (10), wherein, include: The outer casing (2) has a pressure relief section (22111) at at least one end along a first direction (Z), the pressure relief section (22111) being configured to at least partially open during pressure relief; An electrode assembly (1) is at least partially disposed within the housing (2). The electrode assembly (1) has a wound structure and is provided with a central hole (101) extending along the first direction (Z). The electrode assembly (1) includes two electrodes (11) with opposite polarities. At least one of the electrodes (11) includes an electrode body (111) and an electrode tab (112) arranged along the first direction (Z). The electrode body (111) is coated with an active material layer (1111). At least a portion of the electrode tab (112) is not coated with the active material layer (1111). The electrode tab (112) and the electrode body (111) are both disposed around the outer periphery of the central hole (101). The electrode tab (112) includes a plurality of bent pieces (1121) distributed along the winding direction (W) of the electrode assembly (1). At least one of the plurality of pieces (1121) is bent toward the central hole (101), and at least one of the plurality of pieces (1121) is bent away from the central hole (101). Along the winding direction (W) of the electrode assembly (1), a cut-off groove (102) is provided between any two adjacent pieces (1121). On a projection plane perpendicular to the first direction (Z), the orthographic projection of the central hole (101) and the orthographic projection of the first groove bottom surface (103) of at least one cut-off groove (102) are both located within the orthographic projection of the pressure relief part (22111).

2. The cylindrical battery cell (10) according to claim 1, wherein, The pressure relief section (22111) 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 (11) is released to the outside of the housing (2).

3. The cylindrical battery cell (10) according to claim 1 or 2, wherein, At least one of the segments (1121) has a bent section (11211) at one end in the first direction (Z), the bent section (11211) including at least one first bent portion (112111) bent relative to the electrode body (111) toward the center hole (101) and at least one second bent portion (112112) bent relative to the electrode body (111) toward the direction away from the center hole (101).

4. The cylindrical battery cell (10) according to claim 3, wherein, Both the first bent portion (112111) and the second bent portion (112112) are bent along the radial (Y) direction of the electrode assembly (1).

5. The cylindrical battery cell (10) according to claim 3 or 4, wherein, The first bent portion (112111) and the second bent portion (112112) are alternately arranged along the first direction (Z).

6. The cylindrical battery cell (10) according to any one of claims 3-5, wherein, Each of the segments (1121) has a bent segment (11211) at one end in the first direction (Z).

7. The cylindrical battery cell (10) according to any one of claims 1-6, wherein, Both of the electrode plates (11) include the electrode plate body (111) and the electrode tab (112). The electrode tabs (112) of the two electrode plates (11) are respectively disposed at both ends of the electrode assembly (1) along the first direction (Z). The electrode tab (112) of each electrode plate (11) includes a plurality of the slits (1121). On the projection plane perpendicular to the first direction (Z), the orthographic projection of the bottom surface (103) of the first groove of at least one of the cut-off grooves (102) on the electrode tab (112) of each electrode plate (11) is located within the orthographic projection of the pressure relief part (22111).

8. The cylindrical battery cell (10) according to any one of claims 1-7, wherein, The two electrodes (11) include a positive electrode (11a) and a negative electrode (11b), wherein the tab (112) of the positive electrode (11a) and / or the tab (112) of the negative electrode (11b) are not coated with the active material layer (1111).

9. The cylindrical battery cell (10) according to claim 8, wherein, In the first direction (Z), on the positive electrode (11a), the tab (112) is provided with an insulating layer (113) in the end region near the electrode body (111), and the cut piece (1121) is located on the side of the insulating layer (113) away from the electrode body (111).

10. The cylindrical battery cell (10) according to any one of claims 1-9, wherein, The tab (112) further includes a transition connection portion (1122). The electrode body (111), the transition connection portion (1122), and the segment (1121) are arranged sequentially along the first direction (Z). The transition connection portion (1122) and any two segments (1121) adjacent to the winding direction (W) of the electrode assembly (1) form the cut-off groove (102). The first groove bottom surface (103) of the cut-off groove (102) is formed on one side edge of the transition connection portion (1122) used to connect the segment (1121).

11. The cylindrical battery cell (10) according to claim 10, wherein, The dimension of one side edge of each of the segments (1121) used to connect the transition connection (1122) in the winding direction (W) of the electrode assembly (1) is L1, and the sum of the dimensions of the transition connection (1122) and the segments (1121) in the first direction (Z) is L2, 0.01≤L2 / L1≤0.

3.

12. The cylindrical battery cell (10) according to claim 10 or 11, wherein, The dimension of the transition connection (1122) in the first direction (Z) is L3, 0.1mm≤L3≤2mm.

13. The cylindrical battery cell (10) according to any one of claims 1-12, wherein, The housing (2) further includes a first end wall (221) opposite to the electrode assembly (1) along the first direction (Z), the first end wall (221) having a first groove (201) and the pressure relief portion (22111) located in the area enclosed by the first groove (201), the bottom of the first groove (201) having a weak portion (22112), the pressure relief portion (22111) being connected to the weak portion (22112), at least a portion of the weak portion (22112) being configured to be disconnected during pressure relief to open the pressure relief portion (22111).

14. The cylindrical battery cell (10) according to any one of claims 1-12, characterized in that, The outer casing (2) further includes a first wall (2212) and a pressure relief mechanism (2211). The first wall (2212) is disposed opposite to the electrode assembly (1) along the first direction (Z). The first wall (2212) is fixedly connected to the pressure relief mechanism (2211). The pressure relief mechanism (2211) is provided with a first groove (201) and a pressure relief portion (22111) located in the area enclosed by the first groove (201). A weak portion (22112) is provided at the bottom of the first groove (201). 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 disconnected during pressure relief to open the pressure relief portion (22111).

15. The cylindrical battery cell (10) according to any one of claims 1-14, wherein, On the projection plane perpendicular to the first direction (Z), the outer contour of the orthographic projection of the pressure relief part (22111) is circular.

16. The cylindrical battery cell (10) according to any one of claims 1-15, wherein, At least one of the electrode plates (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), and in the radial direction (Y) of the electrode assembly (1), the winding start end (104) is closer to the center hole (101) than the winding end end (105). The tab (112) near the winding start end (104) is provided with a first notch (106), the first notch (106) penetrates the winding start end (104) along the winding direction (W) of the electrode assembly (1), and extends along the end face of the tab (112) away from the electrode body (111). The tab (112) has a winding start section (11221) located at one end of the first notch (106) near the electrode body (111). In the first direction (Z), the tab (1121) extends beyond the bottom surface (107) of the second groove of the first notch (106) in a direction away from the electrode body (111). The bottom surface (107) of the second groove is the end face of the winding start section (11221) away from the electrode body (111).

17. The cylindrical battery cell (10) according to claim 16, wherein, The cylindrical battery cell (10) further includes a current collector (3), at least a portion of which is disposed within the housing (2); On a projection plane perpendicular to the first direction (Z), the orthographic projection of the winding start section (11221) is located within the orthographic projection of the pressure relief section (22111), and the current collection member (3) is welded to the segment (1121) but not to the winding start section (11221).

18. The cylindrical battery cell (10) according to any one of claims 1-17, wherein, At least one of the electrode plates (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), and in the radial direction (Y) of the electrode assembly (1), the winding start end (104) is closer to the center hole (101) than the winding end end (105). The tab (112) near the winding end (105) is provided with a second notch (108), the second notch (108) penetrates the winding end (105) along the winding direction (W) of the electrode assembly (1), and penetrates the end face of the tab (112) away from the electrode body (111); The tab (112) has a wound end section (11222) located at one end of the second notch (108) near the electrode body (111). In the first direction (Z), the cut piece (1121) extends beyond the bottom surface (109) of the third groove of the second notch (108) in a direction away from the electrode body (111). The bottom surface (109) of the third groove is the end face of the wound end section (11222) away from the electrode body (111).

19. The cylindrical battery cell (10) according to claim 18, wherein, The cylindrical battery cell (10) further includes a current collector (3), at least a portion of which is disposed within the housing (2); The current collecting component (3) is welded to the segment (1121) and not to the winding end segment (11222).

20. The cylindrical battery cell (10) according to any one of claims 1-19, wherein, The cylindrical battery cell (10) further includes a current collector (3), at least a portion of which is disposed within the housing (2), and the current collector (3) is welded to the segment (1121) to form a first welded portion (4).

21. The cylindrical battery cell (10) according to claim 20, wherein, On the projection plane perpendicular to the first direction (Z), the two ends of the orthographic projection of the first welded part (4) have a first projection endpoint (M1) and a second projection endpoint (M2), respectively. The first projection endpoint (M1) is closer to the central hole (101) than the second projection endpoint (M2). The area between the first arc line (M3) that passes through the first projection endpoint (M1) and surrounds the central hole (101) and the second arc line (M4) that passes through the second projection endpoint (M2) and surrounds the central hole (101) is the first transverse area (M5). At least a portion of the cut-off grooves (102) form the first group of grooves. In the first group of grooves, the orthographic projection of the bottom surface (103) of the first groove of all the cut-off grooves (102) is located within the first transverse area (M5). Wherein, in the first group of slots, the number of turns of a single cut-off slot (102) is ≤3; and / or, in the first group of slots, the number of cut-off slots (102) that are opposite and connected in the radial (Y) direction of the electrode assembly (1) is ≤3.

22. The cylindrical battery cell (10) according to claim 20 or 21, wherein, The cylindrical battery cell (10) also includes an electrode terminal (5) fixed to the outer casing (2), and the electrode terminal (5) is welded to the current collector (3) to form a second welded part (6).

23. The cylindrical battery cell (10) according to claim 22, wherein, On the projection plane perpendicular to the first direction (Z), the two ends of the orthographic projection of the second welded part (6) have a third projection endpoint (N1) and a fourth projection endpoint (N2), respectively. The third projection endpoint (N1) is closer to the center hole than the fourth projection endpoint (N2). The area between the third arc line (N3) that passes through the third projection endpoint (N1) and surrounds the center hole (101) and the fourth arc line (N4) that passes through the fourth projection endpoint (N2) and surrounds the center hole (101) is the second transverse area (N5). At least a portion of the cut-off grooves (102) form a second group of grooves. In the second group of grooves, the orthographic projection of the bottom surface (103) of the first groove of all the cut-off grooves (102) is located within the second transverse area (N5). In the second set of slots, the number of turns of a single cut-off slot (102) is ≤3; and / or, in the second set of slots, the number of cut-off slots (102) that are opposite to and connected along the radial (Y) direction of the electrode assembly (1) is ≤3.

24. The cylindrical battery cell (10) according to claim 22 or 23, wherein, At least one of the electrode plates (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), and in the radial direction (Y) of the electrode assembly (1), the winding start end (104) is closer to the center hole (101) than the winding end end (105). The tab (112) near the winding start end (104) is provided with a first notch (106). The first notch (106) penetrates the winding start end (104) along the winding direction (W) of the electrode assembly (1) and penetrates the end face of the tab (112) away from the electrode body (111). The tab (112) has a winding start section (11221) located on the side of the first notch (106) near the electrode body (111). In the first direction (Z), the cut (1121) extends beyond the bottom surface (107) of the second groove of the first notch (106) in a direction away from the electrode body (111). The bottom surface (107) of the second groove is the end face of the winding start section (11221) away from the electrode body (111). In the radial (Y) direction of the electrode assembly (1), the first welding portion (4) is located outside the first notch (106); and / or, in the radial (Y) direction of the electrode assembly (1), the second welding portion (6) is located outside the first notch (106).

25. The cylindrical battery cell (10) according to any one of claims 22-24, wherein, At least one of the electrode plates (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), and in the radial direction (Y) of the electrode assembly (1), the winding start end (104) is closer to the center hole (101) than the winding end end (105). The tab (112) near the winding end (105) is provided with a second notch (108). The second notch (108) penetrates the winding end (105) along the winding direction (W) of the electrode assembly (1) and penetrates the end face of the tab (112) away from the electrode body (111). The tab (112) has a wound end section (11222) located on the side of the second notch (108) near the electrode body (111). In the first direction (Z), the cut piece (1121) extends beyond the bottom surface (109) of the third groove of the second notch (108) in a direction away from the electrode body (111). The bottom surface (109) of the third groove is the end face of the wound end section (11222) away from the electrode body (111). In the radial (Y) direction of the electrode assembly (1), the second notch (108) is located outside the first weld portion (4); and / or, in the radial (Y) direction of the electrode assembly (1), the second notch (108) is located outside the second weld portion (6).

26. The cylindrical battery cell (10) according to any one of claims 20-25, wherein, Both of the electrode plates (11) include the electrode plate body (111) and the electrode tab (112), wherein the electrode tab (112) of one electrode plate (11) is a first electrode tab and the electrode tab (112) of the other electrode plate (11) 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 (1) along the first direction (Z); In the first direction (Z), both ends of the electrode assembly (1) are provided with the current collecting member (3), and the current collecting member (3) located at both ends of the electrode assembly (1) are respectively the first current collecting member (3a) and the second current collecting member (3b); The outer casing (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 the first direction (Z), and an electrode terminal (5) is provided on the second end wall (211). The first current collector (3a) is welded to the segment (1121) of the first electrode tab and electrically connected to the electrode terminal (5). The second current collector (3b) is welded to the segment (1121) of the second electrode tab and electrically connected to the sidewall (212).

27. The cylindrical battery cell (10) according to claim 26, wherein, The second current collector (3b) is welded to the first end wall (221), and the side wall (212) is electrically connected to the first end wall (221).

28. The cylindrical battery cell (10) according to claim 26, wherein, In the radial (Y) direction of the electrode assembly (1), the sidewall (212) protrudes inward to form a protrusion (2121), the protrusion 2121 and the electrode assembly (1) are distributed along the first direction (Z), and the second current collector (3b) is welded to the side of the protrusion (2121) close to or away from the electrode assembly (1).

29. The cylindrical battery cell (10) according to any one of claims 26-28, wherein, The first electrode is a positive electrode (112a), and the second electrode is a negative electrode (112b).

30. The cylindrical battery cell (10) according to any one of claims 26-29, wherein, The first end wall (221) is provided with the pressure relief part (22111).

31. The cylindrical battery cell (10) according to any one of claims 20-30, wherein, The flow collecting member (3) is provided with an exhaust through hole (301) extending along the first direction (Z), and the exhaust through hole (301) is opposite to and connected to the center hole (101) along the first direction (Z); The flow collecting component (3) is also provided with a plurality of guide portions (32), which are spaced apart around the outer periphery of the exhaust through hole (301).

32. The cylindrical battery cell (10) according to claim 31, wherein, The guide portion (32) extends to the exhaust port (301); Alternatively, 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 less than or equal to 10 mm.

33. The cylindrical battery cell (10) according to claim 31 or 32, wherein, On the 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) or coincides with the outer contour of the orthographic projection of the pressure relief portion (22111).

34. The cylindrical battery cell (10) according to any one of claims 31-33, wherein, The guide portion (32) includes a through hole extending through the current collecting member (3) along the first direction (Z); Alternatively, the guide portion (32) may include a second groove that does not penetrate the flow collector (3) along the first direction (Z).

35. The cylindrical battery cell (10) according to any one of claims 1-34, wherein, At least one of the electrode plates (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), and in the radial direction (Y) of the electrode assembly (1), the winding start end (104) is closer to the center hole (101) than the winding end end (105). Of the plurality of segments (1121) of the tab (112), the segment (1121) closest to the winding end (105) is wound at least one turn.

36. The cylindrical battery cell (10) according to any one of claims 1-35, wherein, The tab (112) is provided with a plurality of cut-off grooves (102), and the cut-off grooves (102) and the cut pieces (1121) are arranged alternately in the winding direction (W) of the electrode assembly (1).

37. The cylindrical battery cell (10) according to any one of claims 1-36, wherein, In the first direction (Z), the size of the slit (1121) along the winding direction (W) of the electrode assembly (1) tends to decrease in the direction away from the electrode body (111).

38. The cylindrical battery cell (10) according to any one of claims 1-37, wherein, The outer diameter of the electrode assembly (1) is D1, and the diameter of the central hole (101) is D2, where D2 / D1 ∈ [5%, 25%].

39. A battery device (100), wherein, Includes the cylindrical battery cell (10) according to any one of claims 1-38.

40. An electrical appliance, wherein, Includes a cylindrical battery cell (10) according to any one of claims 1-38; or includes a battery device (100) according to claim 39.

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