Cylindrical battery cell, battery device, and electric device

Abstract

The present application relates to the technical field of batteries, and provides a cylindrical battery cell, a battery device, and an electric device. The cylindrical battery cell comprises a casing, an electrode assembly, and a first current collector member. A protrusion is protrudingly arranged on an inner surface of the casing. The protrusion is of an annular structure extending in the circumferential direction of the cylindrical battery cell. A wall portion of the casing is provided with a pressure relief component. The pressure relief component is provided with a pressure relief groove. The electrode assembly is accommodated in an accommodating cavity. In a first direction, at least part of the first current collector member is arranged between the electrode assembly and the protrusion, the first current collector member is connected to the electrode assembly and the protrusion and divides the accommodating cavity of the casing into a first cavity and a second cavity, and the second cavity is located between the first current collector member and the wall portion. In the first direction, the maximum size of the second cavity is H1, the maximum size of the casing is H2, and the following conditions are met: 0.003≤H1 / H2≤0.06, and 0.4 mm≤H1≤4 mm, so as to improve the use reliability and the energy density of the cylindrical battery cell.

Description

Cylindrical battery cells, battery packs and electrical devices Technical Field

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

[0002] In recent years, new energy vehicles have experienced rapid development. In the field of electric vehicles, power batteries, as the power source, play an irreplaceable and crucial role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also increasing. Among them, battery devices, as core components of new energy vehicles, have high requirements in terms of reliability and service life.

[0003] In battery technology, to ensure the safety of cylindrical battery cells, a pressure relief structure is typically installed on the casing of the cell to release internal pressure. This structure is activated to release pressure when the internal pressure or temperature reaches a threshold. However, existing cylindrical battery cells have a low pressure relief rate in the event of thermal runaway, posing a risk of fire and explosion due to delayed pressure relief, thus resulting in low reliability.

[0004] Summary of the Invention

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

[0006] In a first aspect, embodiments of this application provide a cylindrical battery cell, wherein the axial direction of the cylindrical battery cell is a first direction, and the cylindrical battery cell includes a shell, an electrode assembly, and a first current collector; a receiving cavity is formed inside the shell, and a protrusion is provided on the inner surface of the shell, the protrusion being an annular structure extending circumferentially along the cylindrical battery cell, and the shell has a wall portion, on which a pressure relief component is provided, the pressure relief component being provided with a pressure relief groove; the electrode assembly is received within the receiving cavity; the first current collector is disposed within the receiving cavity, and along the first direction, at least a portion of the first current collector is disposed on the electrode assembly. Between the protrusion and the first current collector, the electrode assembly is connected to the protrusion, and the receiving cavity is divided into a first cavity and a second cavity. The electrode assembly is housed in the first cavity, and the second cavity is located between the first current collector and the wall. The pressure relief component is configured to split at least a portion along the pressure relief groove when the cylindrical battery cell is depressurized, so as to release the internal pressure of the second cavity. The maximum size of the second cavity is H1 along the first direction, and the maximum size of the outer shell is H2, satisfying 0.003≤H1 / H2≤0.06 and 0.4mm≤H1≤4mm.

[0007] In the above technical solution, the first current collector divides the internal cavity of the casing into a first cavity and a second cavity arranged along a first direction. The electrode assembly is disposed in the first cavity, and the second cavity is located between the wall and the first current collector. By configuring the pressure relief component on the wall to be able to crack along at least a portion of the pressure relief groove and release the internal pressure of the second cavity when the cylindrical battery cell is depressurized, the area of ​​the pressure relief component on the wall with the pressure relief groove corresponds to the structure of the second cavity. The cylindrical battery cell with this structure can achieve separation between the electrode assembly and the pressure relief groove through the second cavity, thereby alleviating the obstruction and shielding of the pressure relief groove by the electrode assembly when the cylindrical battery cell is depressurized. This allows the interior of the casing to have a second cavity for buffering and releasing thermal runaway gases, which is beneficial to improving the internal exhaust smoothness of the cylindrical battery cell. In addition, the first current collector can also provide a certain degree of support for the electrode assembly. The second cavity plays a role in counteracting the expansion of the electrode assembly during the use of cylindrical battery cells. By setting the maximum size of the second cavity in the first direction to 0.003 to 0.06 of the maximum size of the outer shell in the first direction, and setting the maximum size of the second cavity in the first direction to 0.4 mm to 4 mm, on the one hand, sufficient space is provided between the first current collector and the wall to buffer and discharge thermal runaway gas, which is beneficial to improving the internal venting smoothness and depressurization rate of the cylindrical battery cell. This reduces the risk of the cylindrical battery cell bursting or exploding due to untimely depressurization, thereby improving the reliability of the cylindrical battery cell. On the other hand, it alleviates the phenomenon that the second cavity occupies too much space in the accommodating cavity for setting the electrode assembly in the first direction, thereby improving the internal space utilization of the cylindrical battery cell and increasing the energy density of the cylindrical battery cell.

[0008] In some embodiments, 0.01 ≤ H1 / H2 ≤ 0.03.

[0009] In the above technical solution, on the one hand, the maximum size of the second cavity in the first direction is further set to be greater than or equal to 0.01 times the maximum size of the outer shell in the first direction, so that there is more space between the first current collector and the wall to buffer and discharge thermal runaway gas. This is beneficial to further improve the internal exhaust smoothness and pressure relief rate of the cylindrical battery cell, thereby further reducing the risk of the cylindrical battery cell bursting or exploding due to untimely pressure relief. On the other hand, the maximum size of the second cavity in the first direction is further set to be less than or equal to 0.03 times the maximum size of the outer shell in the first direction, so as to further alleviate the phenomenon that the second cavity occupies too much space in the cavity for setting electrode components, thereby further improving the internal space utilization rate of the cylindrical battery cell and further improving the energy density of the cylindrical battery cell.

[0010] In some embodiments, along the radial direction of the cylindrical battery cell, the inner diameter of the protrusion is D1, and the outer diameter of the electrode assembly is D2, satisfying that 0.7≤D1 / D2≤0.95 and 35mm≤D2≤55mm.

[0011] In the above technical solution, by setting the ratio of the inner diameter of the protrusion to the outer diameter of the electrode assembly to 0.7 to 0.95, and setting the outer diameter of the electrode assembly to 35mm to 55mm, on the one hand, setting the inner diameter of the protrusion to be greater than or equal to 0.7 times the outer diameter of the electrode assembly, so that most of the area of ​​the electrode assembly is a structure set on the inner side of the protrusion in the first direction, thereby reducing the obstruction of the protrusion on the exhaust path inside the cylindrical battery cell, which is conducive to improving the internal exhaust smoothness and pressure relief rate of the cylindrical battery cell, and thus reducing the risk of the cylindrical battery cell bursting or exploding due to untimely pressure relief. On the other hand, setting the inner diameter of the protrusion to be less than or equal to 0.95 times the outer diameter of the electrode assembly, so that the electrode assembly and the protrusion are a structure with overlapping projections in the first direction, which is conducive to improving the support effect of the protrusion on the electrode assembly through the first current collector, and also improving the effect of the first current collector against the expansion of the electrode assembly during the use of the cylindrical battery cell.

[0012] In some embodiments, 0.75 ≤ D1 / D2 ≤ 0.9.

[0013] In the above technical solution, on the one hand, the inner diameter of the protrusion is further set to be greater than or equal to 0.75 times the outer diameter of the electrode assembly, so as to further increase the area of ​​the region of the electrode assembly corresponding to the inner side of the protrusion in the first direction. This can further reduce the obstruction of the protrusion on the exhaust path inside the cylindrical battery cell, which is conducive to further improving the internal exhaust smoothness and pressure relief rate of the cylindrical battery cell. This can further reduce the risk of the cylindrical battery cell bursting or exploding due to untimely pressure relief. On the other hand, the inner diameter of the protrusion is further set to be less than or equal to 0.9 times the outer diameter of the electrode assembly, so as to further increase the area of ​​the region where the electrode assembly and the protrusion overlap in the first direction. This can further improve the support effect of the protrusion on the electrode assembly through the first current collector, and can also further improve the effect of the first current collector against the expansion of the electrode assembly during the use of the cylindrical battery cell.

[0014] In some embodiments, the projection of the pressure relief groove is located within the second cavity along the first direction.

[0015] In the above technical solution, by setting the pressure relief groove as a structure whose projection in the first direction is located in the second cavity, the area where the pressure relief component on the wall is provided with the pressure relief groove is a structure corresponding to the second cavity in the first direction. This makes it easier to discharge the thermal runaway gas in the second cavity when the cylindrical battery cell experiences thermal runaway and the pressure relief component cracks open along at least part of the pressure relief groove to release pressure. This is beneficial to further improve the emission rate of the thermal runaway gas in the second cavity, thereby further improving the pressure relief rate of the cylindrical battery cell and further reducing the risk of the cylindrical battery cell bursting or exploding due to untimely pressure relief.

[0016] In some embodiments, the capacity of the cylindrical battery cell is C, which satisfies 0.005mm / Ah ≤ H1 / C ≤ 0.2mm / Ah.

[0017] In the above technical solution, on the one hand, by setting the ratio of the maximum size of the second cavity in the first direction to the capacitance of the cylindrical battery cell to be greater than or equal to 0.005 mm / Ah, the second cavity has sufficient space to buffer and discharge thermal runaway gas when the cylindrical battery cell is depressurized. This helps to match the space inside the casing used for venting with the gas generation rate of the cylindrical battery cell during thermal runaway, thereby improving the internal venting smoothness of the cylindrical battery cell and effectively reducing the risk of the cylindrical battery cell bursting or exploding due to untimely depressurization. On the other hand, by setting the ratio of the maximum size of the second cavity in the first direction to the capacitance of the cylindrical battery cell to be less than or equal to 0.2 mm / Ah, the phenomenon of excessive waste of space inside the casing used for venting is alleviated, thereby improving the internal space utilization rate of the cylindrical battery cell and increasing the energy density of the cylindrical battery cell.

[0018] In some embodiments, the positive electrode material of the cylindrical battery cell includes lithium transition metal oxide, and H1 and C further satisfy 0.01mm / Ah≤H1 / C≤0.2mm / Ah; or, the positive electrode material of the cylindrical battery cell includes lithium phosphate, and H1 and C further satisfy 0.005mm / Ah≤H1 / C≤0.1mm / Ah.

[0019] In the above technical solution, when the positive electrode material of the cylindrical battery cell includes lithium transition metal oxide, by further adjusting the ratio of the maximum size of the second cavity in the first direction to the capacitance of the cylindrical battery cell from 0.01 mm / Ah to 0.2 mm / Ah, the space inside the casing used for venting can be further matched with the gas generation rate of the cylindrical battery cell during thermal runaway. On the one hand, this can further improve the internal venting smoothness of the cylindrical battery cell, thereby further reducing the risk of the cylindrical battery cell bursting or exploding due to untimely pressure relief. On the other hand, it can further alleviate the phenomenon of excessive waste of the space inside the casing used for venting, thereby further improving the internal space utilization rate of the cylindrical battery cell, which is conducive to further improving the energy density of the cylindrical battery cell. Similarly, when the positive electrode material of the cylindrical battery cell includes lithium phosphate, by further adjusting the ratio of the maximum size of the second cavity in the first direction to the capacitance of the cylindrical battery cell from 0.005 mm / Ah to 0.1 mm / Ah, the space inside the casing used for venting can be further matched with the gas generation rate of the cylindrical battery cell during thermal runaway. On the one hand, this can further improve the internal venting smoothness of the cylindrical battery cell, thereby further reducing the risk of the cylindrical battery cell bursting or exploding due to untimely pressure relief. On the other hand, it can further alleviate the phenomenon of excessive waste of the space inside the casing used for venting, thereby further improving the internal space utilization rate of the cylindrical battery cell, which is conducive to further improving the energy density of the cylindrical battery cell.

[0020] In some embodiments, a plurality of weak regions are formed on the first current collector, the plurality of weak regions being spaced apart circumferentially along the cylindrical battery cell, and the weak regions extending radially along the cylindrical battery cell.

[0021] In the above technical solution, by setting multiple weak regions on the first current collector that are spaced apart circumferentially along the cylindrical battery cell, and each weak region is a structure that extends radially along the cylindrical battery cell, when the cylindrical battery cell experiences thermal runaway, the area surrounded by the multiple weak regions of the first current collector can be ruptured and blown open under the impact of the thermal runaway gas. This can further reduce the obstruction of the exhaust path inside the cylindrical battery cell by the first current collector, which is conducive to further improving the smoothness of internal exhaust and the pressure relief rate of the cylindrical battery cell. In this way, it can further reduce the risk of the cylindrical battery cell bursting or exploding due to untimely pressure relief, thereby improving the reliability of the cylindrical battery cell.

[0022] In some embodiments, along the radial direction of the cylindrical battery cell, the distance from one end of the weak region away from the center of the first current collector to the center of the first current collector is L1, and the length of the weak region is L2, satisfying that L2≥0.8L1.

[0023] In the above technical solution, by setting the radial length of the weak area in the cylindrical battery cell to be greater than or equal to 0.8 times the distance from the end of the weak area away from the center of the first current collector to the center of the first current collector, the weak area extends radially in the cylindrical battery cell to a position closer to the center of the first current collector. This makes the first current collector easier to break and break open under the impact of thermal runaway gas, which helps to reduce the difficulty of the first current collector breaking and breaking open under the impact of thermal runaway gas.

[0024] In some embodiments, 15mm ≤ L1 ≤ 22mm.

[0025] In the above technical solution, by setting the distance from the end of the weak area away from the center of the first current collector to the center of the first current collector to be 15mm to 22mm, on the one hand, the range of the first current collector being broken by thermal runaway gas can be expanded when the cylindrical battery cell is depressurized, thereby improving the smoothness of venting inside the cylindrical battery cell. On the other hand, it can reduce the processing difficulty of the weak area on the first current collector and alleviate the phenomenon that the first current collector does not provide good support for the electrode assembly.

[0026] In some embodiments, the pressure relief groove is an annular structure extending circumferentially along the cylindrical battery cell; wherein, along the radial direction of the cylindrical battery cell, the inner diameter of the pressure relief groove is D3, satisfying 2L1≥0.95D3.

[0027] In the above technical solution, by setting twice the distance from the end of the weak area away from the center of the first current collector to the center of the first current collector as greater than or equal to 0.95 times the inner diameter of the pressure relief groove, the diameter of the area where the first current collector is broken and opened is greater than or equal to 0.95 times the inner diameter of the pressure relief groove. This allows the thermal runaway gas passing through the first current collector to be directly released through the area where the pressure relief groove is provided on the pressure relief component on the wall, which is beneficial to improving the pressure relief smoothness and pressure relief rate of the cylindrical battery cell.

[0028] In some embodiments, 2L1≥D3.

[0029] In the above technical solution, by setting twice the distance from the end of the weak area away from the center of the first current collector to the center of the first current collector as greater than or equal to the inner diameter of the pressure relief groove, the area inside the pressure relief groove is a structure whose projection in the first direction is located in the area where the first current collector is broken and opened. This can further improve the smoothness of the thermal runaway gas passing through the first current collector through the area where the pressure relief groove is provided on the pressure relief component on the wall, which is beneficial to further improve the pressure relief smoothness and pressure relief rate of the cylindrical battery cell.

[0030] In some embodiments, the electrode assembly includes a main body and a first tab, the first tab being connected to one end of the main body facing the first current collector in the first direction, the first tab being welded to the first current collector to form a first connection portion; wherein, in a projection plane perpendicular to the first direction, the orthographic projection of the weak area and the orthographic projection of the first connection portion do not overlap.

[0031] In the above technical solution, by setting the weak area of ​​the first current collector and the first connection part formed by welding the first current collector and the first electrode tab to a structure in which their projections in the first direction do not overlap, on the one hand, the interference effect of the first connection part on the weak area of ​​the first current collector can be reduced, thereby reducing the phenomenon that the first current collector cannot be broken or ruptured under the impact of thermal runaway gas. On the other hand, the phenomenon that the weak area affects the welding quality of the first current collector and the first electrode tab can be alleviated, thereby improving the welding quality and welding stability between the first current collector and the first electrode tab.

[0032] In some embodiments, the weak area is a through hole penetrating the first current collector in the first direction; or, the weak area is a first groove disposed on one side of the first current collector in the first direction.

[0033] In the above technical solution, by setting the weak area as a through hole penetrating the first current collector in the first direction, the first cavity and the second cavity located on both sides of the first current collector can be connected through the weak area while forming the weak area on the first current collector, which is beneficial to further improve the internal venting smoothness of the cylindrical battery cell. Similarly, by setting the weak area as a first groove located on one side of the first current collector in the first direction, the forming difficulty of the weak area on the first current collector can be reduced, and the impact on the overall structural strength of the first current collector can be reduced, so that the first current collector can better support the electrode assembly in the first direction.

[0034] In some embodiments, the first flow collector is provided with a hollow area, which connects the first cavity and the second cavity.

[0035] In the above technical solution, by setting a hollow area connecting the first cavity and the second cavity on the first current collector, the smoothness of thermal runaway gas in the first cavity entering the second cavity and then being released through the pressure relief groove area on the wall is improved. This helps to improve the internal exhaust smoothness and pressure relief rate of the cylindrical battery cell, thereby reducing the risk of the cylindrical battery cell bursting or exploding due to untimely pressure relief.

[0036] In some embodiments, the outer casing has a second groove formed on the side opposite to the receiving cavity and corresponding to the position of the protrusion.

[0037] In the above technical solution, by forming a second groove on the side of the outer shell away from the receiving cavity and at the position corresponding to the protrusion, the protrusion on the inner surface of the outer shell can be a structure that can be formed by stamping. This allows a protrusion to be formed on the side of the outer shell facing the receiving cavity, and a groove to be formed on the other side at the position corresponding to the protrusion. Cylindrical battery cells with this structure can reduce the difficulty of forming protrusions on the inner surface of the outer shell, which is beneficial to improving the production efficiency of cylindrical battery cells. On the other hand, it can realize that the inside of the protrusion is a hollow structure, which enables the protrusion to have the ability of elastic deformation, which helps to alleviate the rigid tension between the first current collector and the protrusion, thereby reducing the risk of connection failure between the first current collector and the protrusion.

[0038] In some embodiments, the protrusion is formed on the side of the wall facing the electrode assembly along the first direction.

[0039] In the above technical solution, by providing a protrusion on the side of the wall facing the electrode assembly, the protrusion is a structure formed on the wall. On the one hand, it can reduce the difficulty of forming the protrusion and reduce the difficulty of assembling the first current collector between the protrusion and the electrode assembly, thereby reducing the manufacturing difficulty of the cylindrical battery cell. On the other hand, it can enable the protrusion to better support the electrode assembly through the first current collector, so that the first current collector can divide the housing cavity into a first cavity and a second cavity arranged along the first direction.

[0040] In some embodiments, the electrode assembly includes a main body and a first tab, the first tab being connected to one end of the main body facing the first current collector in the first direction; wherein the first current collector is welded to the first tab to form a first connection portion, and the first current collector is welded to the protrusion to form a second connection portion, and in a projection plane perpendicular to the first direction, the orthographic projection of the first connection portion and the orthographic projection of the second connection portion do not overlap.

[0041] In the above technical solution, by setting the first connecting part formed by welding the first current collector to the first electrode ear and the second connecting part formed by welding the first current collector to the protrusion to a structure in which their projections in the first direction do not overlap, the influence of the molten pool between the first connecting part and the second connecting part can be reduced, thereby improving the welding quality between the first current collector and the first electrode ear, and also improving the welding quality between the first current collector and the protrusion.

[0042] In some embodiments, the projection of the first connecting portion is located within the second cavity along the first direction.

[0043] In the above technical solution, by setting the first connection part formed by welding the first current collector and the first electrode ear to a structure in which the projection in the first direction is located in the second cavity, the protrusion does not block the area where the first current collector and the first electrode ear are welded together in the first direction, thereby reducing the welding difficulty between the first current collector and the first electrode ear and reducing the interference effect of the protrusion.

[0044] In some embodiments, the housing further includes a sidewall; the sidewall surrounds the wall portion, and one end of the sidewall is connected to the wall portion in the first direction; wherein, along the radial direction of the cylindrical battery cell, the sidewall has the protrusion formed on the side facing the electrode assembly.

[0045] In the above technical solution, by setting the protrusion on the side of the sidewall facing the cavity, the protrusion is a structure formed on the sidewall. This allows the protrusion and the pressure relief groove to be set on different areas of the outer shell, thereby alleviating the phenomenon that the stress of the first current collector acting on the protrusion is transmitted to the area of ​​the pressure relief component on the wall where the pressure relief groove is set. This helps to reduce the impact on the structural strength of the area of ​​the pressure relief component on the wall where the pressure relief groove is set, and thus reduces the phenomenon of premature valve opening and pressure relief in the cylindrical battery cell during use, thereby improving the stability of the cylindrical battery cell in use.

[0046] In some embodiments, the first current collector includes a body portion and a docking portion; the body portion is disposed between the electrode assembly and the protrusion along the first direction, and the body portion is connected to the electrode assembly; the second cavity is located between the body portion and the wall portion in the first direction; at least a portion of the docking portion is located on the side of the body portion facing the protrusion in the first direction, and the docking portion connects the body portion and the protrusion.

[0047] In the above technical solution, the first current collector is provided with a body part and a docking part. The body part is located between the electrode assembly and the protrusion in the first direction and is connected to the electrode assembly. By setting at least a portion of the docking part of the first current collector to be located on the side of the body part facing the protrusion in the first direction, and the docking part connecting the body part and the protrusion, the connection difficulty between the first current collector and the protrusion can be reduced while realizing the electrical connection between the first current collector and the electrode assembly, so as to reduce the assembly difficulty of the first current collector.

[0048] In some embodiments, the mating portion includes a connecting area and an elastic area; the connecting area is located on the side of the body portion facing the protrusion in the first direction, and the connecting area is connected to the protrusion; the elastic area connects the connecting area and the body portion, and the elastic area is configured to deform when the body portion and the connecting area move closer or further apart from each other along the first direction.

[0049] In the above technical solution, the docking part is provided with a connection area and an elastic area. The connection area is connected to the protrusion, and the elastic area is connected between the body part and the connection area to realize the electrical connection between the protrusion and the body part. By setting the connection area in the first direction on the side of the body part facing the protrusion, and setting the elastic area in a structure that can deform when the body part and the connection area move closer or further away from each other in the first direction, the elastic area can play a certain buffering role between the body part and the connection area. In this way, when the electrode assembly shakes or shifts, it can alleviate the rigid tension between the body part and the connection area, between the body part and the electrode assembly, and between the connection area and the protrusion. This is beneficial to further reduce the risk of connection failure between the body part and the electrode assembly and between the connection area and the protrusion, and also to reduce the phenomenon of the first current collector being damaged by tension.

[0050] In some embodiments, along the first direction, the connection area is located on the side of the protrusion facing the electrode assembly.

[0051] In the above technical solution, by setting the connection area of ​​the docking part to be located on the side of the protrusion facing the electrode assembly in the first direction, the connection area and the main body are structured to be located on the same side of the protrusion in the first direction. This can improve the overall support effect of the first current collector on the electrode assembly, and reduce the phenomenon of the docking part occupying the space of the second cavity, which is conducive to improving the exhaust smoothness of thermal runaway gas in the second cavity.

[0052] In some embodiments, along the first direction, the connection area is located on the side of the protrusion facing away from the electrode assembly.

[0053] In the above technical solution, by setting the connection area of ​​the docking part to be located on the side of the protrusion away from the electrode assembly in the first direction, the connection area and the main body are respectively located on both sides of the protrusion in the first direction, and the connection area and the side of the protrusion away from the electrode assembly are connected to each other. The cylindrical battery cell with this structure can, on the one hand, realize that the first current collector and the protrusion can share part of the space in the first direction, which is conducive to improving the internal space utilization of the cylindrical battery cell and thus improving the energy density of the cylindrical battery cell. On the other hand, it can realize that the assembly connection between the connection area and the protrusion is not affected by the interference of the electrode assembly, which is conducive to reducing the assembly difficulty of the connection area of ​​the docking part and the protrusion, and can also help optimize the production process of the cylindrical battery cell.

[0054] In some embodiments, the housing further includes a bottom wall disposed opposite to the wall portion in the first direction, one end of the side wall being connected to the bottom wall in the first direction, and the other end being bent to form a flange portion, the flange portion enclosing an opening, and the wall portion closing the opening; wherein, along the first direction, a portion of the wall portion is located between the flange portion and the protrusion, and the flange portion and the protrusion are configured to cooperate in clamping the wall portion.

[0055] In the above technical solution, by bending the end of the sidewall away from the bottom wall along the first direction to form a flange, and setting part of the wall in the first direction between the protrusion and the flange, the protrusion and the flange can also play a role in assembling and fixing the wall, so as to realize the assembly between the wall and the sidewall. The cylindrical battery cell with this structure can reduce the assembly difficulty between the wall and the sidewall, thereby improving the production efficiency of the cylindrical battery cell.

[0056] In some embodiments, the cylindrical battery cell further includes a seal; at least a portion of the seal is disposed radially between the sidewall and the wall portion of the cylindrical battery cell, and the seal is configured to seal the gap between the wall portion and the sidewall.

[0057] In the above technical solution, the cylindrical battery cell is also provided with a sealing element. By disposing at least a portion of the sealing element in the radial direction of the cylindrical battery cell between the side wall and the wall portion, the sealing element can seal the gap between the wall portion and the side wall, thereby reducing the risk of leakage during the use of the cylindrical battery cell and improving the stability and reliability of the cylindrical battery cell.

[0058] In some embodiments, the first current collector is welded to the protrusion.

[0059] In the above technical solution, by setting the first current collector and the protrusion to a welded connection, it is beneficial to improve the reliability and robustness of the connection between the first current collector and the protrusion, thereby improving the stability of the cylindrical battery cell in use.

[0060] In some embodiments, the pressure relief component is integrally formed with the wall portion.

[0061] In the above technical solution, by setting the pressure relief component as an integral part of the wall, the pressure relief component becomes part of the wall, and the pressure relief groove is directly set on the wall. This eliminates the need for the assembly process between the pressure relief component and the wall, which helps to optimize the processing technology of cylindrical battery cells and improve the production efficiency of cylindrical battery cells.

[0062] In some embodiments, the pressure relief component is separately disposed from the wall portion, and the pressure relief component is connected to the wall portion.

[0063] In the above technical solution, by setting the pressure relief component as a separate structure from the wall, the difficulty of directly machining the pressure relief groove on the wall can be reduced, and the impact on the structural strength of the wall can be reduced.

[0064] In some embodiments, the housing includes a shell and an end cap; the shell includes an integrally formed sidewall and a bottom wall, the sidewall surrounding the bottom wall, one end of the sidewall being connected to the bottom wall along the first direction, and the other end forming an opening, the sidewall and the bottom wall together defining the receiving cavity; the end cap closes the opening; wherein, the wall portion is the end cap.

[0065] In the above technical solution, by setting the wall of the outer casing as an end cap for sealing the opening, the cylindrical battery cell with this structure is easy to install pressure relief components on the end cap, and can reduce the difficulty of assembling the first current collector between the electrode assembly and the protrusion, thereby effectively reducing the manufacturing difficulty of the cylindrical battery cell and improving the production efficiency of the cylindrical battery cell.

[0066] In some embodiments, the housing includes a shell and an end cap; the shell includes an integrally formed sidewall and the wall portion, the sidewall surrounding the wall portion, one end of the sidewall being connected to the wall portion along the first direction, and the other end forming an opening, the sidewall and the wall portion together defining the receiving cavity; the end cap closes the opening.

[0067] In the above technical solution, by setting the wall of the outer casing as a wall away from the end cap in the first direction, the cylindrical battery cell with this structure can ensure that the area of ​​the outer casing with the pressure relief component is away from the end cap. This can effectively alleviate the stress generated by the connection between the end cap and the casing on the pressure relief component, thereby reducing the impact on the area where the pressure relief groove is set on the pressure relief component. This helps to reduce the risk of cracking or structural strength reduction in the area of ​​the pressure relief component with the pressure relief groove on the wall under the action of stress, thus improving the service life and reliability of the cylindrical battery cell.

[0068] Secondly, embodiments of this application also provide a battery device, including the aforementioned cylindrical battery cell.

[0069] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned cylindrical battery cell, wherein the cylindrical battery cell is used to provide electrical energy. Attached Figure Description

[0070] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0071] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0072] Figure 2 is an exploded view of the structure of a battery device provided in some embodiments of this application;

[0073] Figure 3 is a schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of this application;

[0074] Figure 4 is an exploded view of the structure of a cylindrical battery cell provided in some embodiments of this application;

[0075] Figure 5 is a cross-sectional view of a cylindrical battery cell provided in some embodiments of this application;

[0076] Figure 6 is a partial enlarged view of point A of the cylindrical battery cell shown in Figure 5;

[0077] Figure 7 is a partial cross-sectional view of the casing of a cylindrical battery cell provided in some embodiments of this application;

[0078] Figure 8 is an exploded view of the structure of a cylindrical battery cell provided in some embodiments of this application;

[0079] Figure 9 is a cross-sectional view of a cylindrical battery cell provided in some embodiments of this application;

[0080] Figure 10 is a partial enlarged view of point B of the cylindrical battery cell shown in Figure 9;

[0081] Figure 11 is a partial cross-sectional view of the casing of a cylindrical battery cell provided in some embodiments of this application;

[0082] Figure 12 is a front view of the first current collector of a cylindrical battery cell provided in some embodiments of this application in a first direction;

[0083] Figure 13 is a cross-sectional view of a cylindrical battery cell provided in some embodiments of this application;

[0084] Figure 14 is a partial enlarged view of point C of the cylindrical battery cell shown in Figure 13.

[0085] Icons: 1000 - Vehicle; 100 - Battery assembly; 10 - Housing; 11 - First housing body; 12 - Second housing body; 20 - Cylindrical battery cell; 21 - Shell; 211 - Receiving cavity; 2111 - First cavity; 2112 - Second cavity; 212 - Protrusion; 213 - Wall; 2131 - Pressure relief groove; 214 - Housing; 2141 - Opening; 2142 - Bottom wall; 2142a - Mounting hole; 2143 - Side wall; 2143a - Flip 215-End cap; 216-Second groove; 22-Electrode assembly; 221-Main body; 222-First electrode tab; 223-Second electrode tab; 23-First current collector; 231-Weak area; 232-First circle; 233-Body body; 234-Mating part; 2341-Connection area; 2342-Elastic area; 24-Electrode terminal; 25-Second current collector; 26-Seal; 200-Controller; 300-Motor; X-First direction. Detailed Implementation

[0086] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0087] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0088] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0089] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0090] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0091] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0092] In this application, "multiple" means two or more (including two).

[0093] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0094] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0095] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0096] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0097] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0098] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0099] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds.

[0100] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0101] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0102] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0103] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0104] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0105] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0106] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0107] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0108] In some embodiments, the separator is a separator membrane. The separator membrane can be of various types, and any known porous separator membrane with good chemical and mechanical stability can be selected.

[0109] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0110] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0111] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0112] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0113] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0114] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0115] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0116] As an example, polymer solid electrolytes can be polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0117] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0118] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0119] In some implementations, the electrode assembly has a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0120] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0121] In some implementations, the electrode assembly has a positive tab and a negative tab.

[0122] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0123] As an example, a single battery cell can be cylindrical, i.e., a cylindrical battery cell.

[0124] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0125] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0126] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0127] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0128] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0129] As an example, the enclosure may include a first enclosure body and a second enclosure body. The first enclosure body and the second enclosure body are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or shutting down; it can be sealed or not sealed. The first enclosure body may be a top cover or a bottom plate.

[0130] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0131] As an example, the housing can be part of the vehicle's chassis structure. For instance, the housing's roof can be at least part of the vehicle's floor, or the housing's frame can be at least part of the vehicle's crossbeams and longitudinal beams.

[0132] In some embodiments, the battery device refers to an energy storage device, which includes a housing with a door on at least one side. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0133] Battery devices possess outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide applicability, and low self-discharge coefficient, making them an important component of today's new energy development. The development of battery technology must simultaneously consider multiple design factors, such as performance parameters like energy density, cycle life, discharge capacity, and charge / discharge rate. Furthermore, the safety of the battery device must also be taken into account.

[0134] For a typical cylindrical battery cell, the cylindrical battery cell includes a casing and an electrode assembly housed within the casing. One tab of the electrode assembly is electrically connected to the casing, so that the casing serves as an output electrode of the cylindrical battery cell. Correspondingly, the casing of the cylindrical battery cell is usually provided with a pressure relief structure, which can crack when the cylindrical battery cell experiences thermal runaway, thereby releasing the internal pressure of the cylindrical battery cell and thus helping to ensure the safety of the cylindrical battery cell in use. In related technologies, to reduce the difficulty of electrical connection between electrode components and the casing, a current collector is usually set inside the casing. The current collector connects the electrode tabs of the electrode components to the casing to achieve electrical connection between the electrode components and the casing. However, when a cylindrical battery cell with this structure experiences thermal runaway, the current collector inside the casing will obstruct the internal exhaust path or pressure relief structure of the cylindrical battery cell. It is also not conducive to the active material of the electrode components being ejected from the outside of the casing through the pressure relief structure. As a result, the pressure relief rate of the cylindrical battery cell during thermal runaway is low, which makes the cylindrical battery cell susceptible to fire, explosion or connection failure due to untimely pressure relief. This leads to low reliability of the cylindrical battery cell.

[0135] Based on the above considerations, in order to solve the reliability problem of cylindrical battery cells, this application provides a cylindrical battery cell with its axial direction in a first direction. The cylindrical battery cell includes a shell, an electrode assembly, and a first current collector. A receiving cavity is formed inside the shell, and a protrusion is formed on the inner surface of the shell. The protrusion is an annular structure extending circumferentially along the cylindrical battery cell, and the shell has a wall portion. A pressure relief component is provided on the wall portion, and the pressure relief component has a pressure relief groove. The electrode assembly is received within the receiving cavity. The first current collector is disposed within the receiving cavity. Along the first direction, at least a portion of the first current collector is disposed between the electrode assembly and the protrusion. The first current collector connects the electrode assembly and the protrusion and divides the receiving cavity into a first cavity and a second cavity. The electrode assembly is received within the first cavity, and the second cavity is located between the first current collector and the wall portion. The pressure relief component is configured to split along at least a portion of the pressure relief groove when the cylindrical battery cell is depressurized, thereby releasing the internal pressure of the second cavity. Along the first direction, the maximum size of the second cavity is H1, and the maximum size of the outer shell is H2, satisfying that 0.003≤H1 / H2≤0.06 and 0.4mm≤H1≤4mm.

[0136] In this type of cylindrical battery cell, the first current collector divides the internal cavity of the casing into a first cavity and a second cavity arranged along a first direction. The electrode assembly is disposed in the first cavity, and the second cavity is located between the wall and the first current collector. By configuring the pressure relief component on the wall to be able to split along at least a portion of the pressure relief groove and release the internal pressure of the second cavity when the cylindrical battery cell is depressurized, the area of ​​the pressure relief component on the wall with the pressure relief groove corresponds to the structure of the second cavity. The cylindrical battery cell with this structure can achieve separation between the electrode assembly and the pressure relief groove through the second cavity, thereby alleviating the obstruction and shielding of the pressure relief groove by the electrode assembly when the cylindrical battery cell is depressurized. This allows the interior of the casing to have a second cavity for buffering and venting thermal runaway gases, which is beneficial to improving the internal venting smoothness of the cylindrical battery cell. Furthermore, the first current collector can also play a certain role in supporting the electrode assembly. The second cavity provides support and counteracts the expansion of the electrode assembly during the use of the cylindrical battery cell. By setting the maximum size of the second cavity in the first direction to 0.003 to 0.06 times the maximum size of the outer shell in the first direction, and setting the maximum size of the second cavity in the first direction to 0.4 mm to 4 mm, sufficient space is provided between the first current collector and the wall to buffer and discharge thermal runaway gas. This improves the internal venting smoothness and depressurization rate of the cylindrical battery cell, thereby reducing the risk of bursting or exploding due to untimely depressurization and improving the reliability of the cylindrical battery cell. On the other hand, it alleviates the problem of the second cavity occupying too much space in the first direction for setting the electrode assembly, thus improving the internal space utilization of the cylindrical battery cell and increasing its energy density.

[0137] The cylindrical battery cells disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system for such an electrical device can be constructed using the cylindrical battery cells and battery assembly disclosed in this application. This helps to mitigate the problem of fires and explosions caused by untimely pressure release of cylindrical battery cells, thereby improving the reliability of the cylindrical battery cells.

[0138] This application provides an electrical device that uses a cylindrical battery cell or battery assembly as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0139] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device according to an embodiment of this application.

[0140] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside the vehicle 1000. The battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, it can serve as the vehicle's operating power source or general power source. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 controls the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0141] In some embodiments of this application, the battery device 100 can not only serve as the operating power or power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0142] Please refer to Figures 2 and 3. Figure 2 is an exploded view of the structure of a battery device 100 provided in some embodiments of this application, and Figure 3 is a schematic diagram of the structure of a cylindrical battery cell 20 provided in some embodiments of this application. The battery device 100 includes a housing 10 and a cylindrical battery cell 20, which is housed within the housing 10.

[0143] The housing 10 provides an assembly space for the cylindrical battery cell 20, and the housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, which overlap each other, and together define an assembly space for accommodating the cylindrical battery cell 20. The second housing body 12 may be a hollow structure with one end open, and the first housing body 11 may be a plate-like structure, with the first housing body 11 covering the open side of the second housing body 12 so that the first housing body 11 and the second housing body 12 together define the assembly space; alternatively, the first housing body 11 and the second housing body 12 may both be hollow structures with one side open, with the open side of the first housing body 11 covering the open side of the second housing body 12.

[0144] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder, a cuboid, or a cube. For example, in Figure 2, the shape of the box 10 is a cuboid.

[0145] In the battery device 100, there can be one or more cylindrical battery cells 20 disposed within the housing 10. When there are multiple cylindrical battery cells 20 disposed within the housing 10, the multiple cylindrical battery cells 20 can be connected in series, in parallel, or in a mixed manner. A mixed connection means that the multiple cylindrical battery cells 20 are connected in both series and parallel. The multiple cylindrical battery cells 20 can be directly connected in series, in parallel, or in a mixed manner, and then the whole assembly of the multiple cylindrical battery cells 20 is housed within the housing 10. Of course, the battery device 100 can also be in the form of multiple cylindrical battery cells 20 first connected in series, in parallel, or in a mixed manner to form a battery module, and then the multiple battery modules are connected in series, in parallel, or in a mixed manner to form a whole assembly, which is then housed within the housing 10.

[0146] In some embodiments, the battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar for connecting a plurality of cylindrical battery cells 20 to achieve electrical connection between the plurality of cylindrical battery cells 20.

[0147] Each cylindrical battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited to these.

[0148] According to some embodiments of this application, referring to FIG3, and further referring to FIG4, 5, 6 and 7, FIG4 is an exploded view of the structure of a cylindrical battery cell 20 provided in some embodiments of this application, FIG5 is a cross-sectional view of a cylindrical battery cell 20 provided in some embodiments of this application, FIG6 is a partial enlarged view of point A of the cylindrical battery cell 20 shown in FIG5, and FIG7 is a partial cross-sectional view of the outer shell 21 of the cylindrical battery cell 20 provided in some embodiments of this application. This application provides a cylindrical battery cell 20, the axial direction of which is a first direction X. The cylindrical battery cell 20 includes an outer shell 21, an electrode assembly 22 and a first current collector 23. A receiving cavity 211 is formed inside the outer shell 21, and a protrusion 212 is provided on the inner surface of the outer shell 21. The protrusion 212 is an annular structure extending circumferentially along the cylindrical battery cell 20, and the outer shell 21 has a wall portion 213. A pressure relief component is provided on the wall portion 213, and the pressure relief component is provided with a pressure relief groove 2131. The electrode assembly 22 is received in the receiving cavity 211. A first current collector 23 is disposed within the receiving cavity 211. At least a portion of the first current collector 23 is disposed between the electrode assembly 22 and the protrusion 212 along the first direction X. The first current collector 23 connects the electrode assembly 22 and the protrusion 212 and divides the receiving cavity 211 into a first cavity 2111 and a second cavity 2112. The electrode assembly 22 is housed within the first cavity 2111. The second cavity 2112 is located between the first current collector 23 and the wall portion 213. A pressure relief component is configured to split along at least a portion of the pressure relief groove 2131 when the cylindrical battery cell 20 is depressurized, thereby releasing the internal pressure of the second cavity 2112. Along the first direction X, the maximum dimension of the second cavity 2112 is H1, and the maximum dimension of the outer casing 21 is H2, satisfying 0.003 ≤ H1 / H2 ≤ 0.06 and 0.4 mm ≤ H1 ≤ 4 mm.

[0149] Among them, the cylindrical battery cell 20 is cylindrical, and the central axis of the cylindrical battery cell 20 extends along the first direction X. That is to say, the cylindrical battery cell 20 has a cylindrical structure, and the height direction and the axial direction of the cylindrical battery cell 20 are both the first direction X, so that the projection of the cylindrical battery cell 20 in the first direction X is circular.

[0150] Optionally, the outer casing 21 can also be used to contain an electrolyte, such as an electrolyte solution. The outer casing 21 can have various structural forms. The outer casing 21 can also be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0151] In some embodiments, the housing 21 may include a housing 214 and an end cap 215. The housing 214 has an internal cavity 211 with an opening 2141, i.e., the housing 214 is a hollow structure with one end open. The end cap 215 covers the opening 2141 of the housing 214 and forms a sealed connection to form a sealed space for accommodating the electrode assembly 22 and the electrolyte.

[0152] The housing 214 may include a bottom wall 2142 and a side wall 2143. The side wall 2143 surrounds the bottom wall 2142, with one end connected to the bottom wall 2142 and the other end forming an opening 2141. The end cap 215 is disposed opposite to the bottom wall 2142. Correspondingly, the side wall 2143 of the housing 21 is also a cylindrical structure, and the central axis of the side wall 2143 of the housing 21 extends along the first direction X, such that the end cap 215 and the bottom wall 2142 are the end walls of the housing 21 at both ends in the first direction X, and the projections of the end cap 215 and the bottom wall 2142 in the first direction X are both circular, making the end cap 215 and the bottom wall 2142 a disc-shaped structure.

[0153] Optionally, the wall portion 213 with the pressure relief component can be the bottom wall 2142 of the housing 214, or the end cap 215 of the outer shell 21. For example, in Figures 3 and 4, the wall portion 213 is the end cap 215 of the outer shell 21, and correspondingly, the thickness direction of the wall portion 213 is also the first direction X.

[0154] Understandably, the outer casing 21 is not limited to the structure described above. The outer casing 21 can also be other structures. For example, the outer casing 21 includes a shell 214 and two end caps 215. The shell 214 is a hollow structure with openings 2141 on both sides opposite to each other. One end cap 215 is fitted onto one opening 2141 of the shell 214 and forms a sealed connection to form a sealed space for accommodating the electrode assembly 22 and the electrolyte. That is, the shell 214 of the outer casing 21 only includes a side wall 2143. The side wall 2143 is a hollow structure with openings 2141 at both ends in the thickness direction of the wall portion 213. The two end caps 215 are respectively fitted onto the openings 2141 at both ends of the side wall 2143 in the thickness direction of the wall portion 213.

[0155] A pressure relief component is provided on the wall portion 213. The pressure relief component is provided with a pressure relief groove 2131. The pressure relief component is configured to be able to crack along at least a portion of the pressure relief groove 2131 when the cylindrical battery cell 20 is depressurized, so as to release the internal pressure of the cylindrical battery cell 20. That is, the pressure relief component on the wall portion 213 forms a weak structure for pressure relief in the area where the pressure relief groove 2131 is provided, so that when the cylindrical battery cell 20 experiences thermal runaway and releases internal pressure, at least a portion of the area where the pressure relief component on the wall portion 213 is provided with the pressure relief groove 2131 can crack, thereby allowing at least a portion of the pressure relief component located on the inner circumferential side of the pressure relief groove 2131 to be opened and release the internal pressure of the cylindrical battery cell 20.

[0156] It should be noted that the pressure relief component and the wall portion 213 can be integrally formed or separately configured. For example, in Figures 6 and 7, the pressure relief component and the wall portion 213 are integrally formed, with the pressure relief component being a part of the wall portion 213. This allows the pressure relief groove 2131 to be directly disposed on the wall portion 213. In other words, the wall portion 213 is configured to at least partially split along the pressure relief groove 2131 when the cylindrical battery cell 20 is depressurized, thereby releasing the internal pressure of the cylindrical battery cell 20. Of course, in other embodiments, the pressure relief component and the wall portion 213 can also be separately configured. Correspondingly, the pressure relief component can be connected to the wall portion 213 via welding or other structures.

[0157] For example, the pressure relief groove 2131 is an annular structure extending circumferentially along the cylindrical battery cell 20, that is, the pressure relief groove 2131 is an annular groove structure coaxial with the cylindrical battery cell 20. It should be noted that the circumferential direction of the cylindrical battery cell 20 is also the circumferential direction of the sidewall 2143.

[0158] It should be noted that the electrode assembly 22 is the component in the cylindrical battery cell 20 where the electrochemical reaction occurs. The electrode assembly 22 includes a main body 221, a first tab 222, and a second tab 223. The main body 221 is the main component of the electrode assembly 22 in the cylindrical battery cell 20 where the electrochemical reaction occurs, while the first tab 222 and the second tab 223 serve to output or input electrical energy to the electrode assembly 22. The structure of the main body 221 of the electrode assembly 22 can be varied. For example, in FIG. 4, the electrode assembly 22 may include a positive electrode, a separator, and a negative electrode. The main body 221 of the electrode assembly 22 is a wound structure formed by winding the positive electrode portion, the separator portion, and the negative electrode portion. The main body 221 of the electrode assembly 22 has a cylindrical structure, and the central axis of the main body 221 of the electrode assembly 22 extends along the first direction X.

[0159] For example, the separator is a separator membrane, and the main material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0160] Optionally, the electrode assembly 22 housed within the housing 21 can be one or more. For example, in Figure 4, only one electrode assembly 22 is provided within the housing 21 of the cylindrical battery cell 20. Of course, the structure of the cylindrical battery cell 20 is not limited to this; in other embodiments, the electrode assembly 22 housed within the housing 21 can be two, three, four, five, six, seven, or eight, etc.

[0161] The first electrode 222 and the second electrode 223 have opposite polarities. In Figures 4 and 5, the first electrode 222 and the second electrode 223 are respectively connected to the two ends of the main body 221 in the thickness direction of the wall portion 213. In the thickness direction of the wall portion 213, the first electrode 222 is connected to the end of the main body 221 facing the wall portion 213, and the second electrode 223 is connected to the end of the main body 221 away from the wall portion 213.

[0162] It should be noted that if the first tab 222 is the positive tab of the electrode assembly 22, then the first tab 222 is a component formed by stacking and connecting the regions on the positive electrode sheet that are not coated with the positive active material layer. Correspondingly, if the second tab 223 is the negative tab of the electrode assembly 22, then the second tab 223 is a component formed by stacking and connecting the regions on the negative electrode sheet that are not coated with the negative active material layer. Conversely, if the first tab 222 is the negative tab of the electrode assembly 22, then the first tab 222 is a component formed by stacking and connecting the regions on the negative electrode sheet that are not coated with the negative active material layer. Correspondingly, if the second tab 223 is the positive tab of the electrode assembly 22, then the second tab 223 is a component formed by stacking and connecting the regions on the positive electrode sheet that are not coated with the positive active material layer.

[0163] In this embodiment, the inner surface of the outer shell 21 is provided with a protrusion 212. The protrusion 212 is an annular structure extending circumferentially along the cylindrical battery cell 20. That is, the side of the outer shell 21 facing the receiving cavity 211 is provided with a protrusion 212, and the protrusion 212 is an annular structure extending circumferentially along the cylindrical battery cell 20. In other words, the protrusion 212 is a circular structure coaxial with the cylindrical battery cell 20.

[0164] At least a portion of the first current collector 23 is disposed between the protrusion 212 and the electrode assembly 22 in the first direction X, and the first current collector 23 divides the receiving cavity 211 into a first cavity 2111 and a second cavity 2112, the second cavity 2112 being located between the first current collector 23 and the wall portion 213 in the first direction X.

[0165] Optionally, referring to Figures 6 and 7, the protrusion 212 may be a structure protruding from the inner surface of the wall portion 213 facing the receiving cavity 211. Correspondingly, in the first direction X, the electrode assembly 22 abuts against the protrusion 212 through the first current collector 23. Of course, in some embodiments, the cylindrical battery cell 20 may also have other structures. Referring to Figures 8, 9, 10 and 11, Figure 8 is an exploded view of the structure of the cylindrical battery cell 20 provided in some embodiments of this application, Figure 9 is a cross-sectional view of the cylindrical battery cell 20 provided in some embodiments of this application, Figure 10 is a partial enlarged view of point B of the cylindrical battery cell 20 shown in Figure 9, and Figure 11 is a partial cross-sectional view of the outer shell 21 of the cylindrical battery cell 20 provided in some embodiments of this application. The protrusion 212 can also be a structure that protrudes from the inner circumferential surface of the side wall 2143 facing the receiving cavity 211. Correspondingly, the electrode assembly 22 is located on the side of the protrusion 212 away from the wall portion 213 in the first direction X, and at least a portion of the first current collector 23 is disposed between the electrode assembly 22 and the protrusion 212 in the first direction X to support the electrode assembly 22.

[0166] In this embodiment of the application, the first current collector 23 serves to electrically connect the electrode assembly 22 and the protrusion 212, so that the outer casing 21 serves as an output electrode of the cylindrical battery cell 20. For example, the material of the first current collector 23 can be various, such as copper, iron, aluminum, steel or aluminum alloy.

[0167] In this configuration, at least a portion of the first current collector 23 is disposed between the electrode assembly 22 and the protrusion 212 along the first direction X, and divides the receiving cavity 211 into a first cavity 2111 and a second cavity 2112. The electrode assembly 22 is accommodated in the first cavity 2111, and the second cavity 2112 is located between the first current collector 23 and the wall portion 213. That is, at least a portion of the first current collector 23 is supported between the protrusion 212 and the electrode assembly 22 in the first direction X, and the portion of the first current collector 23 located between the electrode assembly 22 and the protrusion 212 in the first direction X divides the receiving cavity 211 into a first cavity 2111 and a second cavity 2112 arranged along the first direction X. The first cavity 2111 is located on the side of the first current collector 23 away from the wall portion 213, while the second cavity 2112 is located on the side of the first current collector 23 facing the wall portion 213, such that the first cavity 2111 is used to accommodate the electrode assembly 22.

[0168] The first current collector 23 connects the first tab 222 and the protrusion 212 of the electrode assembly 22 to electrically connect the electrode assembly 22 and the housing 21. Optionally, the connection structure between the first current collector 23 and the first tab 222 can be various, such as adhesive or welded connection. Similarly, the connection structure between the first current collector 23 and the protrusion 212 can also be various, such as adhesive or welded connection. For example, the first current collector 23 is welded to the first tab 222 and the first current collector 23 is welded to the protrusion 212.

[0169] The wall portion 213 is configured to split open at least a portion along the pressure relief groove 2131 when the cylindrical battery cell 20 is depressurized, so as to release the internal pressure of the second cavity 2112. That is, when the cylindrical battery cell 20 is depressurized, after at least a portion of the area of ​​the wall portion 213 where the pressure relief groove 2131 is provided splits open, the second cavity 2112 can be directly connected to the outside of the outer casing 21, so that the thermal runaway gas in the second cavity 2112 can be directly discharged.

[0170] For example, the first cavity 2111 and the second cavity 2112 are interconnected, and the area of ​​the wall portion 213 with the pressure relief groove 2131 is provided in the first direction X corresponding to the second cavity 2112.

[0171] Along the first direction X, the maximum dimension of the second cavity 2112 is H1, that is, H1 is the maximum height dimension of the second cavity 2112 in the first direction X.

[0172] Along the first direction X, the maximum dimension of the outer shell 21 is H2, that is, H2 is the maximum height dimension of the outer shell 21 in the first direction X.

[0173] For example, along the first direction X, the ratio of the maximum size H1 of the second cavity 2112 to the maximum size H2 of the outer shell 21 can be 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.012, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.056, 0.057, 0.058, 0.059, or 0.06, etc.

[0174] Optionally, the maximum dimension H1 of the second cavity 2112 in the first direction X can be 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.8mm, 3mm, 3.2mm, 3.5mm, 3.8mm or 4mm, etc.

[0175] Optionally, the maximum height dimension H2 of the housing 21 in the first direction X is 70mm to 140mm. For example, the maximum height dimension H2 of the housing 21 in the first direction X can be 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm or 140mm, etc.

[0176] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with Comparative Example 1 and Embodiments 1-4. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0177] Comparative Example 1

[0178] 1) Preparation of positive electrode sheet

[0179] LiNi, the positive electrode active material 0.7 Co 0.1 Mn 0.1 A positive electrode slurry is prepared in N-methylpyrrolidone (NMP) using O2, conductive agent Super P, and binder polyvinylidene fluoride (PVDF). The solid content of the positive electrode slurry is 50 wt%, and the solid component is LiNi. 0.7 Co 0.1 Mn 0.1 The mass ratio of O2, Super P, and PVDF is 8:1:1. The positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil and dried at 85°C. After cold pressing, the foil is trimmed, cut, and slit. Then it is dried under vacuum at 85°C for 4 hours to produce the positive electrode sheet.

[0180] 2) Preparation of negative electrode sheet

[0181] Graphite, conductive agent Super P, thickener carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) are mixed evenly in deionized water to prepare a negative electrode slurry. The solid content of the negative electrode slurry is 30 wt%, and the mass ratio of graphite, silicon suboxide, Super P, CMC, and binder styrene-butadiene rubber (SBR) in the solid components is 88:7:3:2. The negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C. Then, it is cold-pressed, trimmed, cut into sheets, and slit. Finally, it is dried under vacuum at 120°C for 12 hours to prepare the negative electrode sheet.

[0182] 3) Preparation of electrolytes

[0183] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), the thoroughly dried electrolyte salt LiPF6 was dissolved in a mixed solvent (the mixed solvent included ethylene carbonate (EC) and diethyl carbonate (DEC), and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a mass ratio of 50:50) and mixed evenly to obtain a liquid electrolyte with a concentration of 1 mol / L.

[0184] 4) Isolation components

[0185] A 16μm polyethylene film was used as the separator.

[0186] 5) Preparation of cylindrical battery cell 20

[0187] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to isolate them. The electrode assembly 22 is then wound up and placed inside an aluminum casing 21. The electrolyte prepared above is injected into the dried casing 21. The process includes encapsulation, settling, formation, shaping, and capacity testing to complete the preparation of the cylindrical battery cell 20. The casing 21 of the cylindrical battery cell 20 has a cylindrical structure, and a pressure relief groove 2131 is provided on the wall 213 of the cylindrical battery cell 20. The pressure relief groove 2131 is an annular groove structure extending circumferentially along the cylindrical battery cell 20. Furthermore, a protruding groove extending circumferentially along the inner wall of the side wall 2143 of the casing 21 is also provided on the inner wall surface of the casing 21. The protrusion 212 of the extended annular structure is provided, and a first current collector 23 is provided between the electrode assembly 22 and the protrusion 212. The first current collector 23 connects the electrode assembly 22 and the protrusion 212, and the first current collector 23 divides the receiving cavity 211 into a first cavity 2111 and a second cavity 2112 arranged along the first direction X. The electrode assembly 22 is received in the first cavity 2111, and the second cavity 2112 is located between the first current collector 23 and the wall portion 213. In the cylindrical battery cell 20 of Comparative Example 1, the maximum dimension H1 of the second cavity 2112 in the first direction X is 0.2 mm, and the maximum dimension H2 of the outer shell 21 in the first direction X is 100 mm.

[0188] The preparation methods of the cylindrical battery cell 20 in Examples 1-4 are the same as those in Comparative Example 1, except that the maximum dimension H1 of the second cavity 2112 in the first direction X and the maximum dimension H2 of the outer shell 21 in the first direction X are different, as shown in Table 1.

[0189] The following experiments, conducted using Comparative Example 1 and Examples 1-4, tested the ratio of the maximum dimension H1 of the second cavity 2112 in the first direction X to the maximum dimension H2 of the outer shell 21 in the first direction X under different conditions. The timeliness of pressure relief for the cylindrical battery cell 20 was tested. The specific experimental methods are as follows:

[0190] (1) Select a heating plate according to the size of the cylindrical battery cell 20. The size of the heating plate should cover the outer periphery of the cylindrical battery cell 20 (i.e. the outer surface of the side wall 2143) as much as possible, and the coverage area should be ≥60%.

[0191] (2) Before testing, charge the cylindrical battery cell 20 to 100% SOC and ensure that the temperature of the cylindrical battery cell 20 is 25±2℃.

[0192] (3) Sensor arrangement:

[0193] a. Arrangement of temperature sensing wires: Apply a layer of Teflon to each side of the outer circumferential surface of the cylindrical battery cell 20 in the radial direction, arrange the temperature sensing wires above the Teflon, and then apply another layer of Teflon.

[0194] b. Voltage sampling line arrangement: A layer of Teflon is attached to the outer shell 21 and the two electrode terminals 24 of the cylindrical battery cell 20. A voltage sampling line is arranged above the Teflon, and then another layer of Teflon is attached.

[0195] c. Air tube arrangement: Drill holes in the wall 213 of the outer casing 21, then insert the air tube into the holes and seal them, and connect the air tube to the air pressure sensor.

[0196] d. Connect the temperature sensing wire, voltage sampling wire, and barometric pressure sensor to the data acquisition instrument to collect and analyze data in real time. The data acquisition frequency of the data acquisition instrument is ≤0.1 seconds.

[0197] (4) Assemble the fixture and clamp the cylindrical battery cell 20 with a clamping force of 3000N. (The arrangement order of the fixture, heating plate and cylindrical battery cell 20 is: fixture + heating plate + cylindrical battery cell 20 + fixture).

[0198] (5) Test: turn on the data acquisition instrument to collect temperature, voltage and air pressure data, and then turn on the heating plate at 500W power to heat the cylindrical battery cell 20 until the cylindrical battery cell 20 experiences thermal runaway.

[0199] (6) Obtain the pressure holding time of the cylindrical battery cell 20. Based on the temperature, voltage and air pressure data collected by the data acquisition instrument, determine the thermal runaway time of the cylindrical battery cell 20 and the valve opening time of the area where the pressure relief groove 2131 is set in the wall 213. Subtract the thermal runaway time of the cylindrical battery cell 20 from the valve opening time of the area where the pressure relief groove 2131 is set in the wall 213 to obtain the pressure holding time of the cylindrical battery cell 20. This allows for testing the timely pressure relief of the cylindrical battery cell 20. The timely pressure relief of the cylindrical battery cell 20 can be used to reasonably predict whether the cylindrical battery cell 20 will explode or burst due to untimely pressure relief in the event of thermal runaway.

[0200] The criteria for determining thermal runaway of cylindrical battery cell 20 are as follows: (a) a voltage drop occurs at the trigger point, and the voltage drops to more than 25% of the initial voltage; (b) the temperature at the detection point reaches the maximum operating temperature specified by the manufacturer; (c) the temperature rise rate at the detection point, dT / dt, is ≥1℃ / s and lasts for more than 3 seconds. When (a) and (c) or (b) and (c) are met, the cylindrical battery cell 20 is determined to have experienced thermal runaway, and the moment of thermal runaway of the cylindrical battery cell 20 is determined.

[0201] Determining the valve opening time of the area where the pressure relief groove 2131 is provided in the wall 213: When the air pressure drops by more than 25%, it can be determined that the area where the pressure relief groove 2131 is provided in the wall 213 has been opened. Therefore, the moment when the air pressure begins to drop is the valve opening time of the area where the pressure relief groove 2131 is provided in the wall 213.

[0202] The experimental results of Comparative Example 1 and Examples 1-4 are shown in Table 1 below.

[0203] Table 1

[0204] Referring to Table 1, based on the experimental results of Comparative Example 1 and Examples 1-4, it can be seen that when the ratio of the maximum dimension H1 of the second cavity 2112 in the first direction X to the maximum dimension H2 of the outer shell 21 in the first direction X is less than 0.003, the suffocation time of the cylindrical battery cell 20 is as high as 3 seconds or more. This results in a high burst pressure required for the cylindrical battery cell 20 during thermal runaway. The area where the pressure relief groove 2131 is provided in the wall 213 cannot be depressurized in time, making the risk of explosion or rupture of the outer shell 21 of the cylindrical battery cell 20 during thermal runaway higher. This leads to low reliability of the cylindrical battery cell 20. Therefore, the ratio of the second cavity 2112 in the first direction X... The ratio of the maximum dimension H1 to the maximum dimension H2 of the outer shell 21 in the first direction X is set to be greater than or equal to 0.003. Specifically, when the ratio of the maximum dimension H1 of the second cavity 2112 in the first direction X to the maximum dimension H2 of the outer shell 21 in the first direction X is 0.003, and the maximum dimension H1 of the second cavity 2112 in the first direction X is greater than or equal to 0.4 mm, the suffocation time of the cylindrical battery cell 20 can reach less than 2 seconds, which makes the risk of the outer shell 21 of the cylindrical battery cell 20 exploding or bursting during thermal runaway lower. Therefore, the maximum dimension H1 of the second cavity 2112 in the first direction X is set to be greater than or equal to 0.4 mm.

[0205] In some embodiments, as shown in Figures 3, 4 and 5, the cylindrical battery cell 20 may further include an electrode terminal 24. The electrode terminal 24 is insulatedly mounted on a wall of the housing 21 facing the second tab 223 in the first direction X. The electrode terminal 24 is electrically connected to the second tab 223, so that the electrode terminal 24 serves as another output electrode of the cylindrical battery cell 20. That is, the electrode terminal 24 can function as an input or output of electrical energy of the cylindrical battery cell 20, thereby enabling the input or output of electrical energy of the cylindrical battery cell 20 through the electrode terminal 24 and the wall portion 213.

[0206] The electrode terminal 24 is insulatedly mounted on a wall of the housing 21 facing the second tab 223 in the first direction X. That is, the electrode terminal 24 is mounted on the end of the housing 214 away from the wall 213 in the first direction X, and an insulating element is provided between the electrode terminal 24 and the housing 21, so that no electrical connection is formed between the electrode terminal 24 and the housing 21.

[0207] Referring to Figure 5, the electrode terminal 24 is riveted to the bottom wall 2142 of the housing 214. That is, the bottom wall 2142 of the housing 214 is provided with a mounting hole 2142a. The mounting hole 2142a penetrates through both sides of the bottom wall 2142 of the housing 214 along the first direction X. A portion of the electrode terminal 24 passes through the mounting hole 2142a. The electrode terminal 24 has a first clamping part located on the side of the bottom wall 2142 of the housing 214 facing the electrode assembly 22 and a second clamping part located on the side of the bottom wall 2142 of the housing 214 away from the electrode assembly 22. At least a portion of the bottom wall 2142 of the housing 214 is located between the first clamping part and the second clamping part in the first direction X, so that the first clamping part and the second clamping part can cooperate to clamp the bottom wall 2142 of the housing 214, so as to realize the riveting of the electrode terminal 24 to the bottom wall 2142 of the housing 214. Of course, in other embodiments, the electrode terminal 24 may also be a structure that is snapped or glued to the housing 21.

[0208] For example, the electrode terminal 24 can be made of various materials, such as copper, iron, aluminum, steel or aluminum alloy.

[0209] In some embodiments, as shown in Figures 4 and 5, the cylindrical battery cell 20 may further include a second current collector 25, which is disposed in a first direction X between the second tab 223 and the electrode terminal 24 of the electrode assembly 22. The second current collector 25 connects the second tab 223 and the electrode terminal 24 to electrically connect the electrode assembly 22 and the electrode terminal 24.

[0210] Optionally, the connection structure between the second current collector 25 and the second electrode tab 223, and between the second current collector 25 and the electrode terminal 24, can be various, such as welding connection or bonding.

[0211] For example, the material of the second current collector 25 can be various, such as copper, iron, aluminum, steel or aluminum alloy.

[0212] It should be noted that in other embodiments, the second tab 223 of the electrode assembly 22 may also be a structure that is directly connected to the electrode terminal 24, such as by welding or bonding.

[0213] In this embodiment, the first current collector 23 divides the receiving cavity 211 inside the housing 21 into a first cavity and a second cavity arranged along the first direction X. The electrode assembly 22 is disposed in the first cavity, and the second cavity is located between the wall portion 213 and the first current collector 23. By configuring the pressure relief component on the wall portion 213 to be able to at least partially crack along the pressure relief groove 2131 and release the internal pressure of the second cavity 2112 when the cylindrical battery cell 20 is depressurized, the area of ​​the wall portion 213 with the pressure relief groove 2131 is corresponding to... The structure of the second cavity 2112 allows the cylindrical battery cell 20 to separate the electrode assembly 22 and the pressure relief groove 2131. This reduces the obstruction and blockage of the pressure relief groove 2131 by the electrode assembly 22 when the cylindrical battery cell 20 is depressurized. The second cavity 2112 inside the outer casing 21 serves to buffer and release thermal runaway gases, improving the internal venting smoothness of the cylindrical battery cell 20. Furthermore, the first current collector 23 can also... The component 22 provides support and counteracts the expansion of the electrode assembly 22 during the use of the cylindrical battery cell 20. By setting the maximum size of the second cavity 2112 in the first direction X to 0.003 to 0.06 of the maximum size of the outer shell 21 in the first direction X, and setting the maximum size of the second cavity 2112 in the first direction X to 0.4 mm to 4 mm, sufficient space is provided between the first current collector 23 and the wall 213 to buffer and discharge thermal runaway gas. This improves the smoothness of internal venting and the depressurization rate of the cylindrical battery cell 20, thereby reducing the risk of bursting or exploding due to untimely depressurization and improving the reliability of the cylindrical battery cell 20. On the other hand, it alleviates the problem of the second cavity 2112 occupying too much space in the receiving cavity 211 for setting the electrode assembly 22 in the first direction X, thereby improving the internal space utilization of the cylindrical battery cell 20 and increasing its energy density.

[0214] In some embodiments, as shown in Figures 5 and 6, and Figures 9 and 10, 0.01 ≤ H1 / H2 ≤ 0.03.

[0215] In this embodiment, on the one hand, the maximum size of the second cavity 2112 in the first direction X is further set to be greater than or equal to 0.01 times the maximum size of the outer shell 21 in the first direction X, so that there is more space between the first current collector 23 and the wall 213 to buffer and discharge thermal runaway gas, which is conducive to further improving the internal exhaust smoothness and depressurization rate of the cylindrical battery cell 20, thereby further reducing the risk of the cylindrical battery cell 20 bursting or exploding due to untimely depressurization. On the other hand, the maximum size of the second cavity 2112 in the first direction X is further set to be less than or equal to 0.03 times the maximum size of the outer shell 21 in the first direction X, so as to further alleviate the phenomenon that the second cavity 2112 occupies too much space in the accommodating cavity 211 for setting the electrode assembly 22, thereby further improving the internal space utilization of the cylindrical battery cell 20 and further improving the energy density of the cylindrical battery cell 20.

[0216] According to some embodiments of this application, referring to Figures 5, 6 and 7 and Figures 9, 10 and 11, along the radial direction of the cylindrical battery cell 20, the inner diameter of the protrusion 212 is D1, and the outer diameter of the electrode assembly 22 is D2, satisfying that 0.7≤D1 / D2≤0.95 and 35mm≤D2≤55mm.

[0217] Wherein, along the radial direction of the cylindrical battery cell 20, the inner diameter of the protrusion 212 is D1, that is, D1 is the diameter of the circle containing the inner contour of the orthographic projection of the protrusion 212 in a projection plane perpendicular to the first direction X. Along the radial direction of the cylindrical battery cell 20, the outer diameter of the electrode assembly 22 is D2, that is, D2 is the diameter of the circle containing the outer contour of the orthographic projection of the main body 221 of the electrode assembly 22 in a projection plane perpendicular to the first direction X. It should be noted that the first direction X is perpendicular to the radial direction of the cylindrical battery cell 20. The radial direction of the cylindrical battery cell 20 is the direction in which the central axis of the cylindrical battery cell 20 points to the outer peripheral surface of the cylindrical battery cell 20 in the projection plane perpendicular to the first direction X, or the direction in which the outer peripheral surface of the cylindrical battery cell 20 points to the central axis of the cylindrical battery cell 20.

[0218] For example, along the radial direction of the cylindrical battery cell 20, the ratio of the inner diameter D1 of the protrusion 212 to the outer diameter D2 of the electrode assembly 22 can be 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.78, 0.8, 0.82, 0.84, 0.85, 0.86, 0.88, 0.9, 0.91, 0.92, 0.93, 0.94, or 0.95, etc.

[0219] For example, the outer diameter D2 of the electrode assembly 22 can be 35mm, 36mm, 37mm, 38mm, 39mm, 40mm, 41mm, 42mm, 43mm, 44mm, 45mm, 46mm, 47mm, 48mm, 49mm, 50mm, 51mm, 52mm, 53mm, 54mm or 55mm, etc.

[0220] In this embodiment, by setting the ratio of the inner diameter of the protrusion 212 to the outer diameter of the electrode assembly 22 to 0.7 to 0.95, and setting the outer diameter of the electrode assembly 22 to 35mm to 55mm, the inner diameter of the protrusion 212 is set to be greater than or equal to 0.7 times the outer diameter of the electrode assembly 22. This results in a large portion of the electrode assembly 22 being a structure corresponding to the inner side of the protrusion 212 in the first direction X. This reduces the obstruction of the protrusion 212 on the exhaust path inside the cylindrical battery cell 20, which is beneficial for improving the internal exhaust of the cylindrical battery cell 20. The smoothness of airflow and the rate of pressure relief can reduce the risk of bursting or exploding of the cylindrical battery cell 20 due to untimely pressure relief. On the other hand, the inner diameter of the protrusion 212 is set to be less than or equal to 0.95 times the outer diameter of the electrode assembly 22, so that the electrode assembly 22 and the protrusion 212 are partially overlapped in the first direction X. This is beneficial to improve the support effect of the protrusion 212 on the electrode assembly 22 through the first current collector 23, and can also improve the effect of the first current collector 23 against the expansion of the electrode assembly 22 during the use of the cylindrical battery cell 20.

[0221] In some embodiments, please continue to refer to Figures 5, 6 and 7, as well as Figures 9, 10 and 11, where 0.75 ≤ D1 / D2 ≤ 0.9.

[0222] In this embodiment, on the one hand, the inner diameter of the protrusion 212 is further set to be greater than or equal to 0.75 times the outer diameter of the electrode assembly 22, so as to further increase the area of ​​the region of the electrode assembly 22 corresponding to the inner side of the protrusion 212 in the first direction X. This can further reduce the obstruction of the exhaust path inside the cylindrical battery cell 20 by the protrusion 212, which is conducive to further improving the smoothness of internal exhaust and pressure relief rate of the cylindrical battery cell 20. This can further reduce the risk of the cylindrical battery cell 20 bursting or exploding due to untimely pressure relief. On the other hand, the inner diameter of the protrusion 212 is further set to be less than or equal to 0.9 times the outer diameter of the electrode assembly 22, so as to further increase the area of ​​the region where the electrode assembly 22 and the protrusion 212 overlap in the first direction X. This can further improve the support effect of the protrusion 212 on the electrode assembly 22 through the first current collector 23, and can also further improve the effect of the first current collector 23 against the expansion of the electrode assembly 22 during the use of the cylindrical battery cell 20.

[0223] According to some embodiments of this application, please continue to refer to Figures 6 and 10. Along the first direction X, the projection of the pressure relief groove 2131 is located within the second cavity 2112. That is, in the first direction X, the area of ​​the wall portion 213 where the pressure relief groove 2131 is provided is the structure corresponding to the second cavity 2112.

[0224] In this embodiment, by setting the pressure relief groove 2131 to a structure in which the projection of the pressure relief groove 2131 in the first direction X is located within the second cavity 2112, the area where the pressure relief component on the wall 213 is provided with the pressure relief groove 2131 is a structure in the first direction X corresponding to the second cavity 2112. This makes it easier for the thermal runaway gas in the second cavity 2112 to be discharged when the cylindrical battery cell 20 experiences thermal runaway and the pressure relief component on the wall 213 cracks along at least part of the pressure relief groove 2131 to release pressure. This is beneficial to further improve the emission rate of the thermal runaway gas in the second cavity 2112, thereby further improving the pressure relief rate of the cylindrical battery cell 20 and further reducing the risk of the cylindrical battery cell 20 bursting or exploding due to untimely pressure relief.

[0225] According to some embodiments of this application, as shown in Figures 6 and 10, the capacity of the cylindrical battery cell 20 is C, which satisfies 0.005mm / Ah ≤ H1 / C ≤ 0.2mm / Ah.

[0226] For example, the ratio of the maximum dimension H1 of the second cavity 2112 in the first direction X to the capacity C of the cylindrical battery cell 20 can be 0.005 mm / Ah, 0.006 mm / Ah, 0.007 mm / Ah, 0.008 mm / Ah, 0.009 mm / Ah, 0.01 mm / Ah, 0.02 mm / Ah, 0.03 mm / Ah, 0.04 mm / Ah, or 0.05 mm / Ah. h, 0.06mm / Ah, 0.07mm / Ah, 0.08mm / Ah, 0.09mm / Ah, 0.1mm / Ah, 0.11mm / Ah, 0.12mm / Ah, 0.13 mm / Ah, 0.14mm / Ah, 0.15mm / Ah, 0.16mm / Ah, 0.17mm / Ah, 0.18mm / Ah, 0.19mm / Ah or 0.2mm / Ah, etc.

[0227] In this embodiment, on the one hand, by setting the ratio of the maximum size of the second cavity 2112 in the first direction X to the capacitance of the cylindrical battery cell 20 to be greater than or equal to 0.005 mm / Ah, the second cavity 2112 has sufficient space to buffer and discharge thermal runaway gas when the cylindrical battery cell 20 is depressurized. This helps to match the space for venting inside the casing 21 with the gas generation rate of the cylindrical battery cell 20 during thermal runaway, thereby improving the smoothness of internal venting of the cylindrical battery cell 20. This effectively reduces the risk of the cylindrical battery cell 20 bursting or exploding due to untimely depressurization. On the other hand, by setting the ratio of the maximum size of the second cavity 2112 in the first direction X to the capacitance of the cylindrical battery cell 20 to be less than or equal to 0.2 mm / Ah, the excessive waste of space for venting inside the casing 21 is alleviated, thereby improving the utilization rate of the internal space of the cylindrical battery cell 20 and increasing the energy density of the cylindrical battery cell 20.

[0228] In some embodiments, as shown in Figures 6 and 10, the positive electrode material of the cylindrical battery cell 20 includes lithium transition metal oxide, and H1 and C further satisfy 0.01mm / Ah≤H1 / C≤0.2mm / Ah.

[0229] The positive electrode material of the cylindrical battery cell 20 includes lithium transition metal oxide, that is, the positive electrode material of the electrode assembly 22 of the cylindrical battery cell 20 includes at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and their modified compounds.

[0230] In this embodiment, when the positive electrode material of the cylindrical battery cell 20 includes lithium transition metal oxide, by further adjusting the ratio of the maximum size of the second cavity 2112 in the first direction X to the capacitance of the cylindrical battery cell 20 from 0.01 mm / Ah to 0.2 mm / Ah, the space for venting inside the casing 21 can be further matched with the gas generation rate of the cylindrical battery cell 20 during thermal runaway. On the one hand, this can further improve the smoothness of internal venting of the cylindrical battery cell 20, thereby further reducing the risk of the cylindrical battery cell 20 bursting or exploding due to untimely pressure relief. On the other hand, it can further alleviate the phenomenon of excessive waste of space for venting inside the casing 21, thereby further improving the internal space utilization rate of the cylindrical battery cell 20, which is conducive to further improving the energy density of the cylindrical battery cell 20.

[0231] In some embodiments, please continue to refer to Figures 6 and 10, the positive electrode material of the cylindrical battery cell 20 includes lithium phosphate, and H1 and C further satisfy 0.005mm / Ah≤H1 / C≤0.1mm / Ah.

[0232] The positive electrode material of the cylindrical battery cell 20 includes lithium phosphate, that is, the positive electrode material of the electrode assembly 22 of the cylindrical battery cell 20 includes at least one of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0233] In this embodiment, when the positive electrode material of the cylindrical battery cell 20 includes lithium phosphate, by further adjusting the ratio of the maximum size of the second cavity 2112 in the first direction X to the capacitance of the cylindrical battery cell 20 from 0.005 mm / Ah to 0.1 mm / Ah, the space for venting inside the casing 21 can be further matched with the gas generation rate of the cylindrical battery cell 20 during thermal runaway. On the one hand, this can further improve the smoothness of internal venting of the cylindrical battery cell 20, thereby further reducing the risk of the cylindrical battery cell 20 bursting or exploding due to untimely pressure relief. On the other hand, it can further alleviate the phenomenon of excessive waste of space for venting inside the casing 21, thereby further improving the internal space utilization rate of the cylindrical battery cell 20, which is conducive to further improving the energy density of the cylindrical battery cell 20.

[0234] According to some embodiments of this application, referring to Figures 5 and 6, and further referring to Figure 12, Figure 12 is a front view of the first current collector 23 of a cylindrical battery cell 20 provided in some embodiments of this application in a first direction X. A plurality of weak regions 231 are formed on the first current collector 23, the plurality of weak regions 231 being spaced apart circumferentially along the cylindrical battery cell 20, and the weak regions 231 extending radially along the cylindrical battery cell 20.

[0235] In this configuration, multiple weak zones 231 are spaced apart circumferentially along the cylindrical battery cell 20, and the weak zones 231 extend radially along the cylindrical battery cell 20. That is, the multiple weak zones 231 provided on the first current collector 23 are arranged around the central axis of the cylindrical battery cell 20, and each weak zone 231 is a strip structure extending radially along the cylindrical battery cell 20, so that the multiple weak zones 231 provided on the first current collector 23 are in a radial shape, so that the ends of the multiple weak zones 231 away from the center of the first current collector 23 are all located on the first circle 232, and the center of the first circle 232 is located on the central axis of the cylindrical battery cell 20.

[0236] For example, in Figure 12, the first current collector 23 is provided with four weak regions 231. The four weak regions 231 are spaced apart and evenly arranged along the circumference of the cylindrical battery cell 20, and each weak region 231 is a strip-shaped structure extending radially along the cylindrical battery cell 20. Of course, in other embodiments, the number of weak regions 231 provided on the first current collector 23 can also be two, three, five, six or seven, etc.

[0237] In this embodiment, by providing multiple weak regions 231 arranged circumferentially around the cylindrical battery cell 20 on the first current collector 23, and each weak region 231 being a structure extending radially along the cylindrical battery cell 20, when the cylindrical battery cell 20 experiences thermal runaway, the area surrounded by the multiple weak regions 231 of the first current collector 23 can be ruptured and blown open under the impact of the thermal runaway gas. This further reduces the obstruction of the exhaust path inside the cylindrical battery cell 20 by the first current collector 23, which is beneficial to further improve the smoothness of internal exhaust and the pressure relief rate of the cylindrical battery cell 20. In turn, it can further reduce the risk of the cylindrical battery cell 20 bursting or exploding due to untimely pressure relief, thereby improving the reliability of the cylindrical battery cell 20.

[0238] According to some embodiments of this application, referring to FIG12, along the radial direction of the cylindrical battery cell 20, the distance from one end of the weak region 231 away from the center position of the first current collector 23 to the center position of the first current collector 23 is L1, and the length of the weak region 231 is L2, satisfying that L2≥0.8L1.

[0239] Among them, the distance from the end of the weak area 231 that is far from the center of the first current collector 23 in the radial direction of the cylindrical battery cell 20 to the center of the first current collector 23 is L1, that is, the radius of the first circle 232 is L1.

[0240] L2 is the maximum dimension of the weak region 231 in its extension direction.

[0241] In this embodiment of the application, L2≥0.8L1, that is, in the radial direction of the cylindrical battery cell 20, the distance from the center of the weak area 231 near the center of the first current collector 23 to the center of the first circle 232 is less than or equal to 20% of the radius of the first circle 232.

[0242] For example, L2 can be 0.8 times, 0.81 times, 0.82 times, 0.83 times, 0.84 times, 0.85 times, 0.86 times, 0.87 times, 0.88 times, 0.89 times, 0.9 times, 0.91 times, 0.92 times, 0.93 times, 0.94 times, 0.95 times, 0.96 times, 0.97 times, 0.98 times, 0.99 times, or 1 times that of L1. It should be noted that the ends of the multiple weak areas 231 away from the center of the first current collector 23 are all located on the first circle 232, and the center of the first circle 232 is located on the central axis of the cylindrical battery cell 20. However, the length of each weak area 231 in its extension direction can be the same or different.

[0243] In this embodiment, by setting the radial length of the weak region 231 in the cylindrical battery cell 20 to be greater than or equal to 0.8 times the distance from the end of the weak region 231 away from the center of the first current collector 23 to the center of the first current collector 23, the weak region 231 extends radially in the cylindrical battery cell 20 to a position closer to the center of the first current collector 23. This makes it easier for the first current collector 23 to be broken and opened under the impact of thermal runaway gas, which helps to reduce the difficulty of the first current collector 23 breaking and opening under the impact of thermal runaway gas.

[0244] In some embodiments, please continue to refer to Figure 12, 15mm≤L1≤22mm.

[0245] For example, along the radial direction of the cylindrical battery cell 20, the distance L1 from one end of the weak area 231 away from the center position of the first current collector 23 to the center position of the first current collector 23 can be 15mm, 15.5mm, 16mm, 16.5mm, 17mm, 17.5mm, 18mm, 18.5mm, 19mm, 19.5mm, 20mm, 20.5mm, 21mm, 21.5mm or 22mm, etc.

[0246] In this embodiment, by setting the distance from the end of the weak area 231 away from the center of the first current collector 23 to the center of the first current collector 23 to 15mm to 22mm, on the one hand, the range of the first current collector 23 being broken by thermal runaway gas can be expanded when the cylindrical battery cell 20 is depressurized, thereby improving the smoothness of venting inside the cylindrical battery cell 20. On the other hand, the processing difficulty of the weak area 231 on the first current collector 23 can be reduced, and the phenomenon of poor support effect of the first current collector 23 on the electrode assembly 22 can be alleviated.

[0247] According to some embodiments of this application, and in conjunction with Figures 6, 7, and 12, the pressure relief groove 2131 is an annular structure extending circumferentially along the cylindrical battery cell 20. Along the radial direction of the cylindrical battery cell 20, the inner diameter of the pressure relief groove 2131 is D3, satisfying 2L1 ≥ 0.95D3.

[0248] Wherein, along the radial direction of the cylindrical battery cell 20, the inner diameter of the pressure relief groove 2131 is D3, that is, D3 is the diameter of the circle containing the inner contour of the orthographic projection of the pressure relief groove 2131 in the projection plane perpendicular to the first direction X.

[0249] 2L1≥0.95D3, which means that the diameter of the first circle 232 is greater than or equal to 0.95 times the inner diameter of the pressure relief groove 2131.

[0250] For example, 2L1 can be 0.95 times, 0.96 times, 0.97 times, 0.98 times, 0.99 times, 1 times, 1.1 times, 1.15 times, 1.2 times, 1.25 times, 1.3 times, 1.35 times, 1.4 times, 1.45 times, 1.5 times, or 1.6 times of D3.

[0251] In this embodiment, by setting twice the distance from the end of the weak area 231 away from the center of the first current collector 23 to the center of the first current collector 23 to be greater than or equal to 0.95 times the inner diameter of the pressure relief groove 2131, the diameter of the area where the first current collector 23 is broken and opened is greater than or equal to 0.95 times the inner diameter of the pressure relief groove 2131. This allows the thermal runaway gas passing through the first current collector 23 to be directly released through the area where the pressure relief groove 2131 is provided on the pressure relief component on the wall 213, which is beneficial to improving the pressure relief smoothness and pressure relief rate of the cylindrical battery cell 20.

[0252] In some embodiments, continuing to refer to Figures 6, 7, and 12, 2L1≥D3. That is, the diameter of the first circle 232 is greater than or equal to the inner diameter of the pressure relief groove 2131, such that the projection of the area of ​​the pressure relief component on the wall 213 located inside the pressure relief groove 2131 in the first direction X lies within the first circle 232 defined by the plurality of weak areas 231.

[0253] In this embodiment, by setting the distance from the end of the weak area 231 away from the center of the first current collector 23 to the center of the first current collector 23 to be greater than or equal to the inner diameter of the pressure relief groove 2131, the area inside the pressure relief groove 2131 is a structure whose projection in the first direction X is located in the area where the first current collector 23 is broken and opened. This can further improve the smoothness of the thermal runaway gas passing through the first current collector 23 through the area where the pressure relief groove 2131 is provided on the pressure relief component on the wall 213, which is beneficial to further improve the pressure relief smoothness and pressure relief rate of the cylindrical battery cell 20.

[0254] According to some embodiments of this application, as shown in Figures 6 and 12, the electrode assembly 22 may include a main body 221 and a first tab 222. The first tab 222 is connected to one end of the main body 221 facing the first current collector 23 in the first direction X. The first tab 222 is welded to the first current collector 23 to form a first connection portion (not shown in the figures). In the projection plane perpendicular to the first direction X, the orthographic projection of the weak area 231 and the orthographic projection of the first connection portion do not overlap.

[0255] The first connecting part is the area where the first current collector 23 and the first electrode 222 are welded together to form a fused area or a welded area to form a solder mark.

[0256] In the projection plane perpendicular to the first direction X, the orthographic projection of the weak area 231 and the orthographic projection of the first connecting part do not overlap. That is to say, the projections of the weak area 231 on the first current collector 23 and the first connecting part in the first direction X do not overlap, making the weak area 231 and the first connecting part a structure that does not contact each other and avoids each other.

[0257] In this embodiment, by setting the weak area 231 of the first current collector 23 and the first connection portion formed by welding the first current collector 23 to the first tab 222 as a structure in which the projections in the first direction X do not overlap, the interference effect of the first connection portion on the weak area 231 of the first current collector 23 can be reduced, thereby reducing the phenomenon that the first current collector 23 cannot be broken or ruptured under the impact of thermal runaway gas. On the other hand, the phenomenon that the weak area 231 affects the welding quality of the first current collector 23 and the first tab 222 can be alleviated, thereby improving the welding quality and welding stability between the first current collector 23 and the first tab 222.

[0258] According to some embodiments of this application, as shown in FIG12, the weak area 231 is a through hole that penetrates the first current collector 23 along the first direction X. That is, the weak area 231 is a through hole structure provided on the first current collector 23, and the through hole penetrates the surfaces of both sides of the first current collector 23 along the first direction X.

[0259] In this embodiment, by setting the weak area 231 as a through hole penetrating the first current collector 23 in the first direction X, the first cavity 2111 and the second cavity 2112 located on both sides of the first current collector 23 can be connected through the weak area 231 while forming the weak area 231 on the first current collector 23, which is beneficial to further improve the internal exhaust smoothness of the cylindrical battery cell 20.

[0260] Of course, the structure of the first current collector 23 is not limited to this. In some embodiments, the first current collector 23 can also be other structures. For example, the weak area 231 is a first groove provided on one side of the first current collector 23 in the first direction X. That is, the first current collector 23 has a first groove on its surface on one side in the first direction X, and the area of ​​the first current collector 23 with the first groove is the weak area 231.

[0261] In this embodiment, by setting the weak area 231 as a first groove located on one side of the first current collector 23 in the first direction X, the molding difficulty of the weak area 231 on the first current collector 23 can be reduced, and the impact on the overall structural strength of the first current collector 23 can be reduced, so that the first current collector 23 can better support the electrode assembly 22 in the first direction X.

[0262] According to some embodiments of this application, as shown in FIG12, the first flow collector 23 is provided with a hollow area, which connects the first cavity 2111 and the second cavity 2112.

[0263] It should be noted that, in Figure 12, the hollow area can also be a through-hole structure provided on the first current collecting member 23, which is the weak area 231 on the first current collecting member 23, so that the first cavity 2111 and the second cavity 2112 can be interconnected at the hollow area. Of course, referring to Figures 9 and 10, in the embodiment where the first current collecting member 23 includes a body part 233 and a docking part 234 connected to each other, and the docking part 234 includes a connecting area 2341 and an elastic area 2342, the hollow area is the gap formed between the body part 233 and the connecting area 2341, so that the first cavity 2111 and the second cavity 2112 can be interconnected at the hollow area.

[0264] In this embodiment, by providing a hollow area on the first current collector 23 that connects the first cavity 2111 and the second cavity 2112, the smoothness of thermal runaway gas in the first cavity 2111 entering the second cavity 2112 and then being released through the pressure relief component on the wall 213 with a pressure relief groove 2131 is improved. This helps to improve the smoothness of internal venting and pressure relief rate of the cylindrical battery cell 20, thereby reducing the risk of the cylindrical battery cell 20 bursting or exploding due to untimely pressure relief.

[0265] According to some embodiments of this application, as shown in Figures 6 and 7 and Figures 10 and 11, a second groove 216 is formed on the side of the housing 21 away from the receiving cavity 211 and at the position corresponding to the protrusion 212.

[0266] The protrusion 212 is an annular structure extending circumferentially along the cylindrical battery cell 20. Correspondingly, the second groove 216 is also an annular groove structure extending circumferentially along the cylindrical battery cell 20.

[0267] For example, the protrusion 212 formed on the side of the outer shell 21 facing the receiving cavity 211 is a structure formed by a stamping process, so that the protrusion 212 is formed on the surface of the outer shell 21 facing the receiving cavity 211, and a second groove 216 is formed on the surface of the outer shell 21 facing away from the receiving cavity 211 at the position corresponding to the protrusion 212. Of course, the forming method of the protrusion 212 formed on the side of the outer shell 21 facing the receiving cavity 211 is not limited to this. In other embodiments, the protrusion 212 formed on the side of the outer shell 21 facing the receiving cavity 211 can also be formed by a processing process such as casting.

[0268] In this embodiment, by forming a second groove 216 on the side of the outer shell 21 away from the receiving cavity 211 and at the position corresponding to the protrusion 212, the protrusion 212 on the inner surface of the outer shell 21 can be formed by stamping. The protrusion 212 is formed on the side of the outer shell 21 facing the receiving cavity 211, and a groove is formed on the other side at the position corresponding to the protrusion 212. The cylindrical battery cell 20 with this structure can reduce the difficulty of forming the protrusion 212 on the inner surface of the outer shell 21, which is beneficial to improving the production efficiency of the cylindrical battery cell 20. On the other hand, it can realize that the inside of the protrusion 212 is a hollow structure, so that the protrusion 212 can have the ability of elastic deformation, which is beneficial to alleviate the rigid tension between the first current collector 23 and the protrusion 212, thereby reducing the risk of connection failure between the first current collector 23 and the protrusion 212.

[0269] According to some embodiments of this application, referring to Figures 5, 6 and 7, a protrusion 212 is formed on the side of the wall portion 213 facing the electrode assembly 22 along the first direction X. That is, the protrusion 212 is a structure formed on the wall portion 213, and the protrusion 212 protrudes from the surface of the wall portion 213 facing the electrode assembly 22 in the first direction X.

[0270] In this embodiment, by providing a protrusion 212 on the side of the wall portion 213 facing the electrode assembly 22, the protrusion 212 is a structure formed on the wall portion 213. On the one hand, it can reduce the molding difficulty of the protrusion 212 and reduce the difficulty of assembling the first current collector 23 between the protrusion 212 and the electrode assembly 22, thereby reducing the manufacturing difficulty of the cylindrical battery cell 20. On the other hand, it can enable the protrusion 212 to better support the electrode assembly 22 through the first current collector 23, so that the first current collector 23 can divide the receiving cavity 211 of the outer shell 21 into a first cavity 2111 and a second cavity 2112 arranged along the first direction X.

[0271] In some embodiments, referring to Figures 4, 5, and 6, the electrode assembly 22 may include a main body 221 and a first tab 222. The first tab 222 is connected to one end of the main body 221 facing the first current collector 23 in the first direction X. The first current collector 23 is welded to the first tab 222 to form a first connection portion, and the first current collector 23 is welded to the protrusion 212 to form a second connection portion (not shown in the figures). In a projection plane perpendicular to the first direction X, the orthographic projections of the first connection portion and the second connection portion do not overlap.

[0272] The first current collector 23 is a disk-shaped structure, and the first current collector 23 is disposed between the protrusion 212 and the electrode assembly 22 in the first direction X, so that the protrusion 212 and the electrode assembly 22 are respectively located on both sides of the first current collector 23 in the first direction X.

[0273] In the projection plane perpendicular to the first direction X, the orthographic projections of the first connecting portion and the second connecting portion do not overlap. That is, the projections of the area where the first current collector 23 is welded to the protrusion 212 and the area where the first current collector 23 is welded to the first electrode tab 222 in the first direction X do not overlap. It should be noted that the second connecting portion is the area where the first current collector 23 and the protrusion 212 are welded together to form a fused region or a weld mark.

[0274] In this embodiment, by setting the first connecting part formed by welding the first current collector 23 to the first tab 222 and the second connecting part formed by welding the first current collector 23 to the protrusion 212 to a structure in which their projections in the first direction X do not overlap, the influence of the molten pool between the first connecting part and the second connecting part can be reduced. This improves the welding quality between the first current collector 23 and the first tab 222, as well as the welding quality between the first current collector 23 and the protrusion 212.

[0275] In some embodiments, as shown in Figures 5 and 6, the projection of the first connecting portion is located within the second cavity 2112 along the first direction X. That is, the area where the first current collector 23 and the first electrode tab 222 are welded together is a structure provided in the first direction X corresponding to the second cavity 2112.

[0276] In this embodiment, by setting the first connection portion formed by welding the first current collector 23 and the first electrode 222 together as a structure in which the projection in the first direction X is located in the second cavity 2112, the protrusion 212 does not block the area where the first current collector 23 and the first electrode 222 are welded together in the first direction X, thereby reducing the welding difficulty between the first current collector 23 and the first electrode 222 and reducing the interference effect of the protrusion 212.

[0277] According to some embodiments of this application, referring to Figures 8, 9, 10, and 11, and further referring to Figures 13 and 14, Figure 13 is a cross-sectional view of a cylindrical battery cell 20 provided in some embodiments of this application, and Figure 14 is a partial enlarged view of point C of the cylindrical battery cell 20 shown in Figure 13. The housing 21 may further include a sidewall 2143, which surrounds the wall portion 213, and one end of the sidewall 2143 is connected to the wall portion 213 in the first direction X. Along the radial direction of the cylindrical battery cell 20, a protrusion 212 is formed on the side of the sidewall 2143 facing the electrode assembly 22.

[0278] The outer casing 21 includes a housing 214 and an end cap 215. The housing 214 includes a bottom wall 2142 and a side wall 2143. One end of the side wall 2143 in the first direction X is connected to the bottom wall 2142, and the other end forms an opening 2141 for the end cap 215 to close. Along the radial direction of the cylindrical battery cell 20, a protrusion 212 is formed on the side of the side wall 2143 facing the electrode assembly 22. That is, the protrusion 212 is formed on the side wall 2143 of the housing 214, and the protrusion 212 protrudes from the inner circumferential surface of the side wall 2143 facing the receiving cavity 211.

[0279] For example, in Figures 9 and 10, the electrode assembly 22 is located on the side of the protrusion 212 away from the outlet 2141 in the first direction X, and at least a portion of the first current collector 23 is located between the protrusion 212 and the electrode assembly 22 in the first direction X.

[0280] In this embodiment, by setting the protrusion 212 on the side of the sidewall 2143 facing the receiving cavity 211, the protrusion 212 is a structure formed on the sidewall 2143, so that the protrusion 212 and the pressure relief groove 2131 are respectively set on different areas of the outer shell 21. This can alleviate the phenomenon that the stress of the first current collector 23 acting on the protrusion 212 is transmitted to the area of ​​the pressure relief component on the wall 213 where the pressure relief groove 2131 is set. This is beneficial to reduce the impact on the structural strength of the area of ​​the pressure relief component on the wall 213 where the pressure relief groove 2131 is set, thereby reducing the phenomenon of premature valve opening and pressure relief in the cylindrical battery cell 20 during use, and improving the stability of the cylindrical battery cell 20 in use.

[0281] According to some embodiments of this application, referring to Figures 10 and 14, the first current collector 23 may include a body portion 233 and a docking portion 234. The body portion 233 is disposed between the electrode assembly 22 and the protrusion 212 along a first direction X, and the body portion 233 is connected to the electrode assembly 22. The second cavity 2112 is located between the body portion 233 and the wall portion 213 in the first direction X. At least a portion of the docking portion 234 is located on the side of the body portion 233 facing the protrusion 212 in the first direction X, and the docking portion 234 connects the body portion 233 and the protrusion 212.

[0282] The body portion 233 of the first current collector 23 is the part where the first current collector 23 and the first electrode tab 222 are connected to each other, and the docking portion 234 is the part where the first current collector 23 and the protrusion 212 are connected to each other in the area 2341. At least a portion of the docking portion 234 is located on the side of the body portion 233 away from the electrode assembly 22 in the first direction X and is spaced apart from the body portion 233.

[0283] Optionally, the body portion 233 and the docking portion 234 of the first current collector 23 can be an integrally formed structure or a separate but connected structure. For example, in Figures 10 and 14, the body portion 233 and the docking portion 234 of the first current collector 23 are integrally formed by integral forming processes such as stamping and cutting.

[0284] In this embodiment, the first current collector 23 is provided with a body portion 233 and a docking portion 234. The body portion 233 is located between the electrode assembly 22 and the protrusion 212 in the first direction X and is connected to the electrode assembly 22. By setting at least a portion of the docking portion 234 of the first current collector 23 to be located on the side of the body portion 233 facing the protrusion 212 in the first direction X, and the docking portion 234 connects the body portion 233 and the protrusion 212, the connection difficulty between the first current collector 23 and the protrusion 212 can be reduced while realizing the electrical connection between the first current collector 23 and the electrode assembly 22 and the protrusion 212, so as to reduce the assembly difficulty of the first current collector 23.

[0285] According to some embodiments of this application, referring to Figures 10 and 14, the mating portion 234 may include a connecting region 2341 and an elastic region 2342. The connecting region 2341 is located on the side of the body portion 233 facing the protrusion 212 in the first direction X, and the connecting region 2341 is connected to the protrusion 212. The elastic region 2342 connects the connecting region 2341 and the body portion 233, and the elastic region 2342 is configured to deform when the body portion 233 and the connecting region 2341 move closer or further apart along the first direction X.

[0286] The body portion 233 of the first current collector 23 is disposed at one end of the electrode assembly 22 in the first direction X near the protrusion 212, and the body portion 233 is connected to the first tab 222 to realize the electrical connection between the first current collector 23 and the first tab 222.

[0287] The connecting area 2341 is disposed on the side of the main body 233 facing the wall 213 in the first direction X, and the connecting area 2341 and the main body 233 are spaced apart. That is, the main body 233 and the connecting area 2341 are arranged at intervals along the first direction X, and the connecting area 2341 is closer to the wall 213 in the first direction X than the main body 233.

[0288] The elastic region 2342 is a structure connecting the main body 233 and the connecting region 2341. The elastic region 2342 is configured to deform when the main body 233 and the connecting region 2341 move closer or further apart along the first direction X. That is, when the first flow collector is compressed or stretched in the first direction X, the elastic region 2342 can deform when the main body 233 and the connecting region 2341 move closer or further apart. It should be noted that the elastic region 2342 can undergo elastic deformation or plastic deformation when it deforms.

[0289] In this embodiment of the application, each connection area 2341 is connected to the main body 233 through an elastic area 2342, and each connection area 2341 is welded to the protrusion 212. For example, the first current collector 23 may include a plurality of docking parts 234, which are arranged at intervals along the circumference of the cylindrical battery cell 20. The elastic area 2342 of each docking part 234 is connected to the docking part 234, and the connection area 2341 is an arc-shaped structure extending along the circumference of the cylindrical battery cell 20.

[0290] Optionally, the connection area 2341 and the elastic area 2342 of the docking part 234 can be an integrally formed structure or a separate but connected structure. For example, in Figures 10 and 14, the connection area 2341 and the elastic area 2342 of the docking part 234 are integrally formed by integral forming processes such as stamping and cutting.

[0291] In this embodiment, the docking portion 234 is provided with a connecting area 2341 and an elastic area 2342. The connecting area 2341 is connected to the protrusion 212, and the elastic area 2342 is connected between the body portion 233 and the connecting area 2341 to realize the electrical connection between the protrusion 212 and the body portion 233. The connecting area 2341 is positioned on the side of the body portion 233 facing the protrusion 212 in the first direction X, and the elastic area 2342 is configured to deform when the body portion 233 and the connecting area 2341 move closer or further apart along the first direction X. The structure allows the elastic zone 2342 to act as a buffer between the body portion 233 and the connecting zone 2341, thereby alleviating the rigid tension between the body portion 233 and the connecting zone 2341, between the body portion 233 and the electrode assembly 22, and between the connecting zone 2341 and the protrusion 212 during the shaking or displacement of the electrode assembly 22. This helps to further reduce the risk of connection failure between the body portion 233 and the electrode assembly 22, and between the connecting zone 2341 and the protrusion 212, and also helps to reduce the phenomenon of the first current collector 23 being damaged by tension.

[0292] In some embodiments, referring to Figures 9 and 10, the connection region 2341 is located on the side of the protrusion 212 facing the electrode assembly 22 along the first direction X. That is, the connection region 2341 and the body portion 233 are located on the same side of the protrusion 212 in the first direction X, and both the connection region 2341 and the body portion 233 are located on the side of the protrusion 212 facing the electrode assembly 22, such that the protrusion 212 is located between the connection region 2341 and the wall portion 213 in the first direction X, so that the connection region 2341 is a structure connected to the side of the protrusion 212 facing the electrode assembly 22.

[0293] In this embodiment, by setting the connection area 2341 of the docking part 234 to be located on the side of the protrusion 212 facing the electrode assembly 22 in the first direction X, the connection area 2341 and the body part 233 are located on the same side of the protrusion 212 in the first direction X. This can improve the overall support effect of the first current collector 23 on the electrode assembly 22, and reduce the phenomenon that the docking part 234 occupies the space of the second cavity 2112, which is conducive to improving the exhaust smoothness of thermal runaway gas in the second cavity 2112.

[0294] In some embodiments, referring to Figures 13 and 14, the connection region 2341 is located on the side of the protrusion 212 away from the electrode assembly 22 along the first direction X. That is, the connection region 2341 and the body portion 233 are respectively located on both sides of the protrusion 212 in the first direction X, and the elastic region 2342 is connected between the connection region 2341 and the body portion 233, so that the elastic region 2342 is located on the inner peripheral side of the protrusion 212, such that the elastic region 2342 and the protrusion 212 share a portion of space in the first direction X, and the connection region 2341 is a structure connected to the side of the protrusion 212 away from the electrode assembly 22.

[0295] In this embodiment, by setting the connection area 2341 of the docking portion 234 to be located on the side of the protrusion 212 away from the electrode assembly 22 in the first direction X, the connection area 2341 and the body portion 233 are respectively located on both sides of the protrusion 212 in the first direction X, and the connection area 2341 and the side of the protrusion 212 away from the electrode assembly 22 are connected to each other. The cylindrical battery cell 20 with this structure can, on the one hand, realize that the first current collector 23 and the protrusion 212 can share part of the space in the first direction X, which is beneficial to improve the internal space utilization of the cylindrical battery cell 20 and thus improve the energy density of the cylindrical battery cell 20. On the other hand, it can realize that the assembly connection between the connection area 2341 and the protrusion 212 is not affected by the interference of the electrode assembly 22, which is beneficial to reduce the assembly difficulty of the connection area 2341 and the protrusion 212 of the docking portion 234, and can also help optimize the production process of the cylindrical battery cell 20.

[0296] According to some embodiments of this application, referring to Figures 8, 9, 10, 13, and 14, the outer casing 21 may further include a bottom wall 2142, which is disposed opposite to the wall portion 213 in a first direction X. One end of the side wall 2143 in the first direction X is connected to the bottom wall 2142, and the other end is bent to form a flange portion 2143a. The flange portion 2143a encloses an opening 2141, and the wall portion 213 closes the opening 2141. Along the first direction X, a portion of the wall portion 213 is located between the flange portion 2143a and the protrusion 212, and the flange portion 2143a and the protrusion 212 are configured to cooperate in clamping the wall portion 213.

[0297] The flange 2143a is a flange structure formed by bending one end of the sidewall 2143 away from the bottom wall 2142 in the first direction X toward the side close to the receiving cavity 211. The flange 2143a surrounds and forms an opening 2141, that is, the flange 2143a is an annular structure, so as to form an opening 2141 on the inner circumference of the flange 2143a.

[0298] In this embodiment, the outer edge of the wall portion 213 extends between the flange portion 2143a and the protrusion 212, so that the flange portion 2143a and the protrusion 212 can cooperate to clamp and assemble a portion of the wall portion 213, thereby realizing the assembly connection between the wall portion 213 and the side wall 2143.

[0299] In this embodiment, by bending one end of the sidewall 2143 away from the bottom wall 2142 along the first direction X to form a flange 2143a, and setting a portion of the wall portion 213 in the first direction X between the protrusion 212 and the flange 2143a, the protrusion 212 and the flange 2143a can also play a role in assembling and fixing the wall portion 213, so as to realize the assembly between the wall portion 213 and the sidewall 2143. The cylindrical battery cell 20 with this structure can reduce the assembly difficulty between the wall portion 213 and the sidewall 2143, thereby improving the production efficiency of the cylindrical battery cell 20.

[0300] According to some embodiments of this application, referring to Figures 10 and 14, the cylindrical battery cell 20 may further include a seal 26. At least a portion of the seal 26 is disposed radially between the sidewall 2143 and the wall portion 213 of the cylindrical battery cell 20, and the seal 26 is configured to seal the gap between the wall portion 213 and the sidewall 2143.

[0301] At least a portion of the seal 26 is disposed radially between the sidewall 2143 and the wall portion 213 of the cylindrical battery cell 20, that is, at least a portion of the seal 26 is located between the outer peripheral surface of the wall portion 213 and the inner peripheral surface of the sidewall 2143, so that the seal 26 can seal the gap between the outer peripheral surface of the wall portion 213 and the inner peripheral surface of the sidewall 2143.

[0302] Optionally, the seal 26 is made of an insulating material, so that the seal 26 can also serve as an insulating barrier between the wall portion 213 and the side. For example, the material of the seal 26 can be rubber, silicone or plastic, etc.

[0303] In this embodiment, the cylindrical battery cell 20 is also provided with a sealing member 26. By disposing at least a portion of the sealing member 26 radially between the side wall 2143 and the wall portion 213 of the cylindrical battery cell 20, the sealing member 26 can seal the gap between the wall portion 213 and the side wall 2143, thereby reducing the risk of leakage during use of the cylindrical battery cell 20 and improving the stability and reliability of the cylindrical battery cell 20.

[0304] In some embodiments, referring to Figures 10 and 14, a portion of the seal 26 is disposed between the wall portion 213 and the protrusion 212 along the first direction X. That is, a portion of the seal 26 is located between the outer peripheral surface of the wall portion 213 and the inner peripheral surface of the sidewall 2143, and a portion of the seal 26 extends between the wall portion 213 and the protrusion 212, such that a portion of the seal 26 is located between the wall portion 213 and the protrusion 212 in the first direction X, so that the seal 26 can also separate the wall portion 213 and the protrusion 212.

[0305] It should be noted that, referring to Figure 14, in the embodiment where the connection area 2341 of the docking portion 234 of the first collector 23 is located on the side of the protrusion 212 facing the wall portion 213 and connected to the protrusion 212, a portion of the seal 26 is located between the connection area 2341 and the wall portion 213, so that the seal 26 can also separate the connection area 2341 and the wall portion 213.

[0306] In this embodiment, by setting a portion of the seal 26 to extend between the wall portion 213 and the protrusion 212, the seal 26 can also seal the gap between the wall portion 213 and the protrusion 212, which is beneficial to further improve the sealing effect of the seal 26 on the gap between the wall portion 213 and the side wall 2143. Furthermore, the protrusion 212 and the wall portion 213 can also play a certain clamping role on the seal 26, which is beneficial to improve the assembly stability of the seal 26.

[0307] In some embodiments, referring again to Figures 10 and 14, a portion of the seal 26 is disposed between the wall portion 213 and the flange portion 2143a along the first direction X. That is, a portion of the seal 26 is located between the outer peripheral surface of the wall portion 213 and the inner peripheral surface of the sidewall 2143, and a portion of the seal 26 extends between the wall portion 213 and the flange portion 2143a, such that a portion of the seal 26 is located between the wall portion 213 and the flange portion 2143a in the first direction X, so that the seal 26 can also separate the wall portion 213 and the flange portion 2143a.

[0308] Optionally, in FIG6, the seal 26 is an annular structure surrounding the wall portion 213. The seal 26 may include a first part, a second part, and a third part arranged and connected in sequence along the first direction X. The first part is located between the protrusion 212 and the wall portion 213 in the first direction X. The second part is located between the outer peripheral surface of the wall portion 213 and the inner peripheral surface of the side wall 2143. The third part is located between the flange portion 2143a and the wall portion 213 in the first direction X.

[0309] In this embodiment, by setting a portion of the seal 26 to extend between the wall portion 213 and the flange portion 2143a, the seal 26 can also seal the gap between the wall portion 213 and the flange portion 2143a, which is beneficial to further improve the sealing effect of the seal 26 on the gap between the wall portion 213 and the side wall 2143. Furthermore, the flange portion 2143a and the wall portion 213 can also play a certain clamping role on the seal 26, which is beneficial to improve the assembly stability of the seal 26.

[0310] According to some embodiments of this application, the first current collector 23 is welded to the protrusion 212.

[0311] For example, the welding connection between the first current collector 23 and the protrusion 212 can be of various types, such as laser welding or ultrasonic welding.

[0312] In this embodiment, by setting the first current collector 23 and the protrusion 212 as a welded connection, it is beneficial to improve the reliability and robustness of the connection between the first current collector 23 and the protrusion 212, thereby improving the stability of the cylindrical battery cell 20 in use.

[0313] According to some embodiments of this application, referring to Figures 6 and 7 and Figures 10 and 11, the pressure relief component is integrally formed with the wall portion 213. That is, the pressure relief component and the wall portion 213 are an integral structure, and the pressure relief component is a part of the wall portion 213. Correspondingly, the pressure relief groove 2131 is a structure directly provided on the wall portion 213, such that the wall portion 213 is configured to be able to crack at least partially along the pressure relief groove 2131 when the cylindrical battery cell 20 is depressurized, so as to release the internal pressure of the cylindrical battery cell 20.

[0314] In this embodiment, by setting the pressure relief component as an integral part of the wall portion 213, the pressure relief component is a part of the wall portion 213, so that the pressure relief groove 2131 is a structure directly set on the wall portion 213. Therefore, there is no need to set up the assembly process between the pressure relief component and the wall portion 213, which is beneficial to optimize the processing technology of the cylindrical battery cell 20 and improve the production efficiency of the cylindrical battery cell 20.

[0315] It should be noted that the structure of the cylindrical battery cell 20 is not limited to this. In other embodiments, the cylindrical battery cell 20 can also have other structures. For example, the pressure relief component and the wall portion 213 can be separately arranged, with the pressure relief component connected to the wall portion 213. That is, the pressure relief component and the wall portion 213 are two independent components, and the pressure relief component and the wall portion 213 are connected to each other. Correspondingly, the pressure relief groove 2131 is provided on the pressure relief component.

[0316] In this embodiment, by setting the pressure relief component as a separate structure from the wall portion 213, the difficulty of directly machining the pressure relief groove 2131 on the wall portion 213 can be reduced, and the impact on the structural strength of the wall portion 213 can be reduced.

[0317] According to some embodiments of this application, referring to Figures 3, 4, 5, and 6, as well as Figures 8, 9, 10, and 11, the outer casing 21 may include a housing 214 and an end cap 215. The housing 214 includes an integrally formed side wall 2143 and a bottom wall 2142. The side wall 2143 surrounds the bottom wall 2142. Along the first direction X, one end of the side wall 2143 is connected to the bottom wall 2142, and the other end forms an opening 2141. The side wall 2143 and the bottom wall 2142 together define a receiving cavity 211. The end cap 215 closes the opening 2141, and the wall portion 213 serves as the end cap 215.

[0318] The shell 214 includes an integrally formed side wall 2143 and a bottom wall 2142, that is, the side wall 2143 and the bottom wall 2142 are integral structures made by an integral forming process, such as stamping or casting.

[0319] The wall portion 213 is an end cap 215, that is, the pressure relief component is disposed on the end cap 215 of the housing 21, and the first current collector 23 is located on the side of the electrode assembly 22 facing the end cap 215 in the first direction X, so that the second cavity 2112 is formed between the end cap 215 and the first current collector 23.

[0320] In this embodiment, by setting the wall portion 213 of the outer casing 21 as an end cap 215 for closing the opening 2141, the cylindrical battery cell 20 with this structure is convenient to set a pressure relief component on the end cap 215, and can reduce the difficulty of assembling the first current collector 23 between the electrode assembly 22 and the protrusion 212, thereby effectively reducing the manufacturing difficulty of the cylindrical battery cell 20 and improving the production efficiency of the cylindrical battery cell 20.

[0321] Of course, the structure of the cylindrical battery cell 20 is not limited to this. In some embodiments, the cylindrical battery cell 20 can also have other structures. For example, the outer casing 21 may include a housing 214 and an end cap 215. The housing 214 includes an integrally formed sidewall 2143 and a wall portion 213. The sidewall 2143 surrounds the wall portion 213. Along the first direction X, one end of the sidewall 2143 is connected to the wall portion 213, and the other end forms an opening 2141. The sidewall 2143 and the wall portion 213 together define a receiving cavity 211. The end cap 215 closes the opening 2141. That is, the pressure relief component is disposed on the bottom wall 2142 of the housing 214, and the first current collector 23 is located on the side of the electrode assembly 22 facing the bottom wall 2142 of the housing 214 in the first direction X, so that the second cavity 2112 is formed between the bottom wall 2142 of the housing 214 and the first current collector 23.

[0322] In this embodiment, by setting the wall portion 213 of the outer casing 21 as a wall of the casing 214 away from the end cap 215 in the first direction X, the cylindrical battery cell 20 with this structure can ensure that the area of ​​the outer casing 21 where the pressure relief component is provided is away from the end cap 215. This can effectively alleviate the phenomenon that the stress generated by the connection between the end cap 215 and the casing 214 acts on the area of ​​the wall portion 213 where the pressure relief component is provided, thereby reducing the impact on the area where the pressure relief component is provided with the pressure relief groove 2131. This helps to reduce the risk of cracking or structural strength reduction in the area of ​​the pressure relief component on the wall portion 213 where the pressure relief groove 2131 is provided under stress, thereby improving the service life and reliability of the cylindrical battery cell 20.

[0323] According to some embodiments of this application, this application also provides a battery device 100, which includes a cylindrical battery cell 20 of any of the above embodiments.

[0324] As shown in Figure 2, the battery device 100 may also include a housing 10, in which cylindrical battery cells 20 are housed.

[0325] In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, the first housing body 11 and the second housing body 12 covering each other, the first housing body 11 and the second housing body 12 together defining an assembly space for accommodating the cylindrical battery cell 20.

[0326] Optionally, the second box body 12 can be a hollow structure with one end open, and the first box body 11 can be a plate-like structure. The first box body 11 covers the open side of the second box body 12 so that the first box body 11 and the second box body 12 together define the assembly space; the first box body 11 and the second box body 12 can also be hollow structures with one side open, and the open side of the first box body 11 covers the open side of the second box body 12.

[0327] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder or a cuboid. For example, in Figure 2, the box 10 is a cuboid structure.

[0328] Optionally, the cylindrical battery cell 20 disposed within the housing 10 can be one or more. For example, in Figure 2, the housing 10 of the battery device 100 contains multiple cylindrical battery cells 20. These cells can be connected in series, parallel, or a combination thereof. A combination thereof means that some of the cylindrical battery cells 20 are connected in series and others in parallel. The multiple cylindrical battery cells 20 can be directly connected in series, parallel, or a combination thereof, and then the entire assembly of the multiple cylindrical battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple cylindrical battery cells 20 first connected in series, parallel, or a combination thereof to form a battery module, and then these battery modules are connected in series, parallel, or a combination thereof to form a whole, which is then housed within the housing 10.

[0329] The battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar component that connects multiple cylindrical battery cells 20 to achieve electrical connection between the multiple cylindrical battery cells 20.

[0330] It should be noted that in some embodiments, the battery device 100 may not have a housing 10. The battery device 100 includes multiple cylindrical battery cells 20, and the battery device 100 composed of multiple cylindrical battery cells 20 can be directly mounted onto the electrical device to provide power to the electrical device through the multiple cylindrical battery cells 20. That is, the housing 10 can be part of the electrical device. Taking a vehicle 1000 as an example, the housing 10 can be part of the chassis structure of the vehicle 1000. For example, a portion of the housing 10 can be at least a part of the floor of the vehicle 1000, or a portion of the housing 10 can be at least a part of the crossbeams and longitudinal beams of the vehicle 1000.

[0331] According to some embodiments of this application, this application also provides an electrical device, which includes a cylindrical battery cell 20 of any of the above schemes, and the cylindrical battery cell 20 is used to provide electrical energy to the electrical device.

[0332] The electrical device can be any of the aforementioned devices or systems that utilize cylindrical battery cells 20.

[0333] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0334] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A cylindrical battery cell, wherein the axial direction of the cylindrical battery cell is a first direction, and the cylindrical battery cell comprises: The outer casing has an internal cavity. The inner surface of the outer casing has a protrusion, which is a ring structure extending circumferentially along the cylindrical battery cell. The outer casing also has a wall portion, on which a pressure relief component is provided, and the pressure relief component is provided with a pressure relief groove. The electrode assembly is housed within the receiving cavity; as well as A first current collector is disposed within the receiving cavity. Along the first direction, at least a portion of the first current collector is disposed between the electrode assembly and the protrusion. The first current collector connects the electrode assembly and the protrusion and divides the receiving cavity into a first cavity and a second cavity. The electrode assembly is received within the first cavity. The second cavity is located between the first current collector and the wall. The pressure relief component is configured to split along at least a portion of the pressure relief groove when the cylindrical battery cell is depressurized, so as to release the internal pressure of the second cavity. Wherein, along the first direction, the maximum size of the second cavity is H1, and the maximum size of the outer shell is H2, satisfying that 0.003≤H1 / H2≤0.06, and 0.4mm≤H1≤4mm.

2. The cylindrical battery cell of claim 1, wherein, 0.01≤H1 / H2≤0.

03.

3. The cylindrical battery cell according to claim 1 or 2, wherein, Along the radial direction of the cylindrical battery cell, the inner diameter of the protrusion is D1, and the outer diameter of the electrode assembly is D2, satisfying that 0.7≤D1 / D2≤0.95, and 35mm≤D2≤55mm.

4. The cylindrical battery cell of claim 3, wherein, 0.75≤D1 / D2≤0.

9.

5. The cylindrical battery cell of any one of claims 1-4, wherein, Along the first direction, the projection of the pressure relief groove is located within the second cavity.

6. The cylindrical battery cell of any one of claims 1-5, wherein, The capacity of the cylindrical battery cell is C, which satisfies the condition 0.005mm / Ah ≤ H1 / C ≤ 0.2mm / Ah.

7. The cylindrical battery cell of claim 6, wherein, The positive electrode material of the cylindrical battery cell includes lithium transition metal oxide, and H1 and C further satisfy the following condition: 0.01 mm / Ah ≤ H1 / C ≤ 0.2 mm / Ah; or The positive electrode material of the cylindrical battery cell includes lithium phosphate, and H1 and C further satisfy the condition that 0.005mm / Ah ≤ H1 / C ≤ 0.1mm / Ah.

8. The cylindrical battery cell of any one of claims 1-7, wherein, The first current collector has multiple weak regions formed on it. The multiple weak regions are arranged circumferentially along the cylindrical battery cell and extend radially along the cylindrical battery cell.

9. The cylindrical battery cell of claim 8, wherein, Along the radial direction of the cylindrical battery cell, the distance from one end of the weak region away from the center of the first current collector to the center of the first current collector is L1, and the length of the weak region is L2, satisfying that L2≥0.8L1.

10. The cylindrical battery cell of claim 9, wherein, 15mm≤L1≤22mm.

11. The cylindrical battery cell according to claim 9 or 10, wherein The pressure relief groove is a ring structure extending circumferentially along the cylindrical battery cell; Wherein, along the radial direction of the cylindrical battery cell, the inner diameter of the pressure relief groove is D3, which satisfies 2L1≥0.95D3.

12. The cylindrical battery cell of claim 11, wherein, 2L1≥D3.

13. The cylindrical battery cell of any one of claims 8-12, wherein, The electrode assembly includes a main body and a first electrode tab. The first electrode tab is connected to one end of the main body facing the first current collector in the first direction. The first electrode tab is welded to the first current collector to form a first connection part. Specifically, in the projection plane perpendicular to the first direction, the orthographic projection of the weak area and the orthographic projection of the first connection portion do not overlap.

14. The cylindrical battery cell of any one of claims 8-13, wherein, The weak area is a through hole penetrating the first current collecting component along the first direction; or The weak area is a first groove located on one side of the first current collector in the first direction.

15. The cylindrical battery cell of any one of claims 1-14, wherein, The first flow collector has a hollow area, which connects the first cavity and the second cavity.

16. The cylindrical battery cell of any one of claims 1-15, wherein, The outer shell has a second groove formed on the side opposite to the receiving cavity and corresponding to the position of the protrusion.

17. The cylindrical battery cell of any one of claims 1-16, wherein, Along the first direction, the protrusion is formed on the side of the wall facing the electrode assembly.

18. The cylindrical battery cell of claim 17, wherein, The electrode assembly includes a main body and a first electrode tab, wherein the first electrode tab is connected to one end of the main body facing the first current collector in the first direction; The first current collector is welded to the first electrode tab to form a first connection part, and the first current collector is welded to the protrusion to form a second connection part. In the projection plane perpendicular to the first direction, the orthographic projection of the first connection part and the orthographic projection of the second connection part do not overlap.

19. The cylindrical battery cell of claim 18, wherein, Along the first direction, the projection of the first connecting portion is located within the second cavity.

20. The cylindrical battery cell of any one of claims 1-19, wherein, The outer casing also includes: A sidewall is provided around the wall portion, and one end of the sidewall in the first direction is connected to the wall portion; The protrusion is formed on the sidewall facing the electrode assembly along the radial direction of the cylindrical battery cell.

21. The cylindrical battery cell of claim 20, wherein, The first current collection component includes: The body portion is disposed between the electrode assembly and the protrusion along the first direction, and the body portion is connected to the electrode assembly. The cavity is located between the body portion and the wall portion in the first direction; The mating portion is at least partially located on the side of the body portion facing the protrusion in the first direction, and the mating portion connects the body portion and the protrusion.

22. The cylindrical battery cell of claim 21, wherein, The docking part includes: A connecting area is located on the side of the body portion facing the protrusion in the first direction, and the connecting area is connected to the protrusion; An elastic region connects the connecting region and the body portion, and the elastic region is configured to deform when the body portion and the connecting region move closer or further apart from each other along the first direction.

23. The cylindrical battery cell of claim 22, wherein, Along the first direction, the connection area is located on the side of the protrusion facing the electrode assembly.

24. The cylindrical battery cell of claim 22, wherein, Along the first direction, the connection area is located on the side of the protrusion opposite to the electrode assembly.

25. The cylindrical battery cell of any one of claims 20-24, wherein, The outer casing also includes a bottom wall, which is disposed opposite to the wall portion in the first direction. One end of the side wall in the first direction is connected to the bottom wall, and the other end is bent to form a flange portion. The flange portion surrounds to form an opening, and the wall portion closes the opening. Wherein, along the first direction, a portion of the wall portion is located between the flange and the protrusion, and the flange and the protrusion are configured to cooperate in clamping the wall portion.

26. The cylindrical battery cell of claim 25, wherein, The cylindrical battery cell also includes: A seal, at least partially disposed radially between the sidewall and the wall portion of the cylindrical battery cell, is configured to seal the gap between the wall portion and the sidewall.

27. The cylindrical battery cell of any one of claims 1-26, wherein, The first current collector is welded to the protrusion.

28. The cylindrical battery cell of any one of claims 1-27, wherein, The pressure relief component is integrally formed with the wall portion.

29. The cylindrical battery cell of any one of claims 1-27, wherein, The pressure relief component is separately disposed from the wall portion, and the pressure relief component is connected to the wall portion.

30. The cylindrical battery cell of any one of claims 1-29, wherein, The outer casing includes: The housing includes an integrally formed sidewall and a bottom wall, the sidewall surrounding the bottom wall, one end of the sidewall being connected to the bottom wall along the first direction, and the other end forming an opening, the sidewall and the bottom wall together defining the receiving cavity; End cap, to close the opening; The wall portion is the end cap.

31. The cylindrical battery cell of any one of claims 1-29, wherein, The outer casing includes: The housing includes an integrally formed sidewall and the wall portion, the sidewall surrounding the wall portion, one end of the sidewall being connected to the wall portion along the first direction, and the other end forming an opening, the sidewall and the wall portion together defining the receiving cavity; End cap, to close the opening.

32. A battery device comprising a cylindrical battery cell as claimed in any one of claims 1-31.

33. An electrical device comprising a cylindrical battery cell as described in any one of claims 1-31, the cylindrical battery cell being used to provide electrical energy.

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