Cylindrical battery cell, battery device, and electric device

Abstract

The application provides a cylindrical battery monomer, a battery device and an electric equipment. The cylindrical battery monomer comprises a shell, an electrode assembly, a first current collecting member and an electrode terminal. The shell comprises a wall part provided with an electrode lead-out hole. The electrode assembly is accommodated in the shell, the electrode assembly and the wall part are arranged along the axial direction of the cylindrical battery monomer, and the electrode assembly comprises a first tab. The first current collecting member is electrically connected to the first tab. The electrode terminal is arranged on the wall part. The electrode terminal comprises a terminal body and a first limiting part, at least part of the terminal body is accommodated in the electrode lead-out hole, at least one side of the terminal body along the axial direction is provided with a recess, the terminal body comprises a connecting part corresponding to the bottom surface of the recess, the connecting part is welded with the first current collecting member, and the first limiting part is connected to the terminal body and protrudes from the outer circumferential surface of the terminal body. At least part of the first limiting part is located on the side of the wall part facing the electrode assembly along the axial direction, and the size of the first limiting part along the axial direction is greater than the size of the connecting part along the axial direction.

Description

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 appliance. Background Technology

[0002] Cylindrical battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] In the development of battery technology, improving the reliability of cylindrical battery cells is a research direction. Utility Model Content

[0004] This application provides a cylindrical battery cell, a battery device, and an electrical device that can improve reliability.

[0005] In a first aspect, embodiments of this application provide a cylindrical battery cell, comprising a housing, an electrode assembly, a first current collector, and electrode terminals. The housing includes a wall portion with an electrode lead-out hole. The electrode assembly is housed within the housing, and the electrode assembly and the wall portion are arranged axially along the cylindrical battery cell. The electrode assembly includes a first tab. The first current collector is housed within the housing and electrically connected to the first tab. The electrode terminals are disposed on the wall portion. The electrode terminals include a terminal body and a first limiting portion. At least a portion of the terminal body is housed within the electrode lead-out hole. The terminal body has a recess on at least one side along the axial direction. The terminal body includes a connecting portion corresponding to the bottom surface of the recess. The connecting portion is welded to the first current collector. The first limiting portion is connected to the terminal body and protrudes from the outer peripheral surface of the terminal body. At least a portion of the first limiting portion is located axially on the side of the wall portion facing the electrode assembly, and the axial dimension of the first limiting portion is larger than the axial dimension of the connecting portion.

[0006] During the assembly of a cylindrical battery cell, the connecting portion and the first current collector can be welded from the outside of the connecting portion, thereby reducing the risk of weld slag sputtering into the casing. By providing a recess, the axial dimension of the connecting portion can be reduced, thereby reducing the power required to weld the connecting portion and the first current collector, reducing welding heat generation, and reducing the risk of burning the electrode assembly. In the proposed embodiment, the axial dimension of the first limiting portion is set to be larger than that of the connecting portion, which can improve the structural strength of the first limiting portion. Even if the recess reduces the strength of the terminal body, the first limiting portion can still resist large internal gas pressure during thermal runaway of the cylindrical battery cell, thereby reducing the bending deformation of the first limiting portion, reducing the possibility of cracking at the connection between the first limiting portion and the terminal body, reducing the risk of the electrode terminal detaching from the wall, which is beneficial for directional pressure relief of the cylindrical battery cell and improving the reliability of the cylindrical battery cell.

[0007] In some embodiments, the ratio of the axial dimension of the first limiting portion to the axial dimension of the connecting portion is 1.1-3.6. In this application embodiment, the ratio is set to be greater than or equal to 1.1, giving the first limiting portion higher structural strength. This reduces the risk of the electrode terminals detaching from the wall during thermal runaway of the cylindrical battery cell, while ensuring the dimensions of the connecting portion meet external welding requirements, thus improving the reliability of the cylindrical battery cell. In this application embodiment, the ratio is set to be less than or equal to 3.6 to reduce the space occupied by the first limiting portion in the axial direction.

[0008] In some embodiments, the axial dimension of the connecting portion is 0.5mm-1.0mm. In this embodiment, the axial dimension of the connecting portion is set to be greater than or equal to 0.5mm to reduce the risk of weld burn-through during welding, improve welding quality, and reduce deformation of the connecting portion during thermal runaway of the cylindrical battery cell. The connecting portion is welded to the first current collector to form a welded portion. In this embodiment, the axial dimension of the connecting portion is set to be greater than or equal to 0.5mm to give the connecting portion sufficient strength, thereby reducing the risk of cracking at the junction of the connecting portion and the welded portion under internal pressure, which is beneficial for directional pressure relief of the cylindrical battery cell. In this embodiment, the axial dimension of the connecting portion is set to be less than or equal to 1mm to reduce the welding power requirements, reduce the heat conducted to the electrode assembly, and reduce the risk of the electrode assembly being burned.

[0009] In some embodiments, the axial dimension of the first limiting portion is 1.1mm-1.8mm. In this application embodiment, the axial dimension of the first limiting portion is set to be greater than or equal to 1.1mm to give the first limiting portion higher structural strength and reduce the risk of the electrode terminals detaching from the wall during thermal runaway of the cylindrical battery cell. In this application embodiment, the axial dimension of the first limiting portion is set to be less than or equal to 1.8mm to reduce the space occupied by the first limiting portion in the axial direction and reduce its impact on the energy density of the cylindrical battery cell.

[0010] In some embodiments, the electrode terminal further includes a second limiting portion, which is connected to the terminal body and protrudes from the outer peripheral surface of the terminal body. A portion of the wall portion is located between the first and second limiting portions along the axial direction, with the first limiting portion being larger than the second limiting portion. By providing the first and second limiting portions, the electrode terminal can be fixed to the wall portion. The first limiting portion has a larger axial dimension, resulting in less deformation during thermal runaway of the cylindrical battery cell, thereby reducing the risk of the electrode terminal detaching from the wall portion during thermal runaway. The second limiting portion has a smaller axial dimension, making it easier to deform during the assembly of the electrode terminal, which helps reduce the difficulty of riveting the electrode terminal to the wall portion.

[0011] In some embodiments, the first limiting portion protrudes more than the second limiting portion from the outer peripheral surface in the radial direction of the cylindrical battery cell. The larger radial dimension of the first limiting portion results in a larger overlap area between it and the wall portion in the axial direction, which helps reduce the risk of the electrode terminals detaching from the wall portion during thermal runaway of the cylindrical battery cell. The smaller radial dimension of the second limiting portion makes it easier to deform during electrode terminal assembly and to be formed by folding, thus reducing the difficulty of riveting the electrode terminals to the wall portion.

[0012] In some embodiments, the ratio of the dimension of the first limiting portion protruding from the outer peripheral surface to the dimension of the second limiting portion protruding from the outer peripheral surface is greater than or equal to 2. Provided the connection strength between the wall portion and the electrode terminal meets the requirements, setting this ratio to be greater than or equal to 2 can further enhance the structural strength of the first limiting portion and reduce the risk of the electrode terminal detaching from the wall portion during thermal runaway of the cylindrical battery cell.

[0013] In some embodiments, the cylindrical battery cell further includes a first insulating member and a protective member, both of which surround the terminal body. Axially, at least a portion of the first insulating member is located between the protective member and the wall portion, and at least a portion of the protective member is located between the first insulating member and the second limiting portion. The tensile strength of the protective member is greater than the tensile strength of the first insulating member.

[0014] The protective component surrounds the outer periphery of the terminal body. During the production or use of the cylindrical battery cell, the protective component restricts the degree of deformation and movement of the terminal body in its radial direction, thereby reducing the deformation of the first insulating component under the force of the terminal body, lowering the risk of cracking of the first insulating component, and improving the reliability of the cylindrical battery cell. Compared with the first insulating component, the protective component has higher tensile strength and is less prone to deformation and cracking under the force of the terminal body, thus reducing the risk of protective component failure and improving the reliability of the cylindrical battery cell.

[0015] In some embodiments, the electrode terminal further includes a transition portion that surrounds the terminal body and is connected to the outer peripheral surface. The transition portion is located on one side of the first limiting portion along the axial direction and is connected to the first limiting portion. In the radial direction of the cylindrical battery cell, the first limiting portion protrudes outward from the transition portion.

[0016] During thermal runaway of a cylindrical battery cell, the terminal body is subjected to the internal gas pressure of the cell. Under the interaction of the wall and the terminal body, the first limiting portion near the root of the terminal body experiences significant stress. The transition portion connects the first limiting portion and the terminal body, which can disperse stress, reduce bending deformation of the first limiting portion, lower the risk of root cracking of the first limiting portion, and reduce the risk of the electrode terminal detaching from the wall, thereby improving the reliability of the cylindrical battery cell.

[0017] In some embodiments, the axial dimension of the transition portion gradually decreases in the direction away from the terminal body. This smooth axial dimension change of the transition portion helps to disperse stress, reduces the risk of root cracking of the first limiting portion and the risk of the electrode terminal detaching from the wall portion, and improves the reliability of the cylindrical battery cell.

[0018] In some embodiments, the maximum axial dimension of the transition portion is 0.1 mm to 0.8 mm; and / or, the radial dimension of the transition portion is 0.1 mm to 0.8 mm. The embodiments of this application can, to a certain extent, balance the strength of the transition portion and the energy density of the cylindrical battery cell.

[0019] In some embodiments, the transition portion is located axially on the side of the first limiting portion opposite to the electrode assembly. In the same plane perpendicular to the axial direction, the orthographic projection of the transition portion lies within the orthographic projection of the electrode lead-out hole. Embodiments of this application can reduce the risk of contact and conduction between the transition portion and the wall portion.

[0020] In some embodiments, the first limiting portion includes an overlapping portion, the orthographic projection of which lies within the projection of the wall portion in the same plane perpendicular to the axial direction. The connecting portion is circular, and the overlapping portion is annular, with the annular width of the overlapping portion greater than or equal to the radius of the connecting portion. The embodiments of this application design the annular width of the overlapping portion according to the radius of the connecting portion, which can reduce the risk of the electrode terminal detaching from the wall portion.

[0021] In some embodiments, the housing includes sidewalls surrounding the electrode assembly, with a wall portion connecting to the sidewalls. At least a portion of the wall portion has a thickness greater than the thickness of the sidewalls.

[0022] By employing sidewalls with a smaller thickness, the internal space of the casing can be increased, thereby improving the energy density of the cylindrical battery cell. Increasing the thickness of at least a portion of the wall can improve its resistance to deformation; in the event of thermal runaway of the cylindrical battery cell, the deformation of the wall under internal gas pressure is smaller, which can constrain the first limiting portion, thus reducing the risk of the electrode terminals detaching from the wall.

[0023] In some embodiments, the thickness of the wall portion is 0.4 mm to 1.2 mm.

[0024] In this embodiment, the wall thickness is set to be greater than or equal to 0.4 mm to reduce wall deformation during thermal runaway of the cylindrical battery cell and lower the risk of electrode terminals detaching from the wall. In another embodiment, the wall thickness is set to be less than or equal to 1.2 mm to reduce the impact of the wall on the energy density of the cylindrical battery cell.

[0025] In some embodiments, the tensile strength of the first limiting portion is 125 MPa-190 MPa. Using a first limiting portion with higher tensile strength can enhance the first limiting portion's resistance to deformation and reduce the risk of the electrode terminal detaching from the wall.

[0026] In some embodiments, the diameter of the cylindrical battery cell is D, and the diameter of the first limiting portion is D1, where 0.65 ≤ D1 / D ≤ 0.80. In this embodiment, setting D1 / D to be greater than or equal to 0.65 increases the area of ​​the first limiting portion constrained by the wall, reducing the risk of the electrode terminals detaching from the wall. In this embodiment, setting D1 / D to be less than or equal to 0.8 reduces the impact of the first limiting portion on the energy density of the cylindrical battery cell and provides space for other components within the casing.

[0027] In some embodiments, the diameter of the terminal body is D2, where 0.30 ≤ D2 / D ≤ 0.50. In this application embodiment, D2 / D is set to be greater than or equal to 0.30 to increase the current-carrying area of ​​the terminal body and reduce heat generation at the electrode terminals during charging and discharging. In this application embodiment, setting D2 / D to be less than or equal to 0.50 can reduce the diameter of the electrode lead-out hole, reduce the impact on the strength of the wall, reduce the deformation of the wall during thermal runaway of the cylindrical battery cell, and reduce the risk of the electrode terminals detaching from the wall.

[0028] In some embodiments, the diameter of the connector is D3, and 0.10 ≤ D3 / D ≤ 0.25. In this embodiment, setting D3 / D to be greater than or equal to 0.1 reduces the difficulty of welding the connector to the first current collector, increases the welding area between the connector and the first current collector, and improves the connection strength and current flow area between the connector and the first current collector. In this embodiment, setting D3 / D to be less than or equal to 0.25 reduces the impact of the recess on the strength of the terminal body and minimizes the deformation of the terminal body during thermal runaway of the cylindrical battery cell.

[0029] In some embodiments, a recess is provided on the side of the terminal body facing away from the electrode assembly. The first current collector can contact the connection portion without extending into the recess, which simplifies the structure of the first current collector.

[0030] In some embodiments, the cylindrical battery cell further includes a cover plate, at least a portion of which is received in the recess and connected to the terminal body. The cover plate can be installed to the terminal body after the connection portion is welded to the first current collector. In the event of thermal runaway of the cylindrical battery cell, the cover plate can constrain the terminal body, reduce the deformation of the terminal body, reduce the stress at the connection between the first limiting portion and the terminal body, reduce the risk of cracking at the connection between the first limiting portion and the terminal body, and reduce the possibility of the electrode terminals detaching from the wall portion. This facilitates directional pressure relief of the cylindrical battery cell and improves its reliability.

[0031] In some embodiments, an opening is formed on the side of the recess away from the connector. The ratio of the diameter of the opening to the diameter of the terminal body is 0.3-0.6. In this embodiment, D4 / D2 is set to be greater than or equal to 0.3, which facilitates welding the connector and the first current collector from the outside; in this embodiment, D4 / D2 is set to be less than or equal to 0.6 to reduce the impact of the recess on the strength of the terminal body and to allow the outer surface of the terminal body to retain a larger area, which is beneficial for connecting the terminal body and the current collector.

[0032] In some embodiments, the electrode terminals are integrally formed. Integral electrode terminals have higher strength.

[0033] In some embodiments, the electrode assembly includes a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes a layered transition metal oxide. The layered transition metal oxide includes a material with the chemical formula Li. a Ni b Co c M d O e A f The compound and its modified compounds contain at least one of the following: 0.8≤a≤1.2, 0.8≤b≤0.95, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes at least one of N, F, S and Cl.

[0034] Cylindrical battery cells with high nickel content have advantages such as high energy density, good low-temperature performance, and good charge-discharge performance. However, cylindrical battery cells with high nickel content have relatively poor thermal stability, and they produce more gas and experience a faster increase in internal gas pressure during thermal runaway. This application's embodiment improves the bending resistance of the first limiting portion by increasing its axial dimension, reducing the likelihood of the electrode terminals detaching from the wall under internal gas pressure. This facilitates directional pressure relief in the high-nickel-content cylindrical battery cells, thereby improving their reliability.

[0035] In some embodiments, the cylindrical battery cell further includes an electrolyte contained within a casing. The electrolyte includes a chain-like ester solvent, with the chain-like ester solvent comprising 25.5 wt% to 76.5 wt% by mass. Embodiments of this application can improve the fast charging and discharging capabilities of the cylindrical battery cell, thereby improving its rate performance. The first limiting portion has high structural strength, and when the chain-like ester solvent decomposes and generates gas, the first limiting portion can also resist the internal gas pressure of the cylindrical battery cell, thereby reducing the risk of the electrode terminals detaching from the wall under internal gas pressure. This facilitates directional pressure relief in cylindrical battery cells with high chain-like ester solvent content, improving the reliability of the cylindrical battery cell.

[0036] In some embodiments, the cylindrical battery cell further includes a pressure relief mechanism disposed on the housing, the pressure relief mechanism being disposed on the side of the electrode assembly away from the electrode terminals. The pressure relief mechanism includes a pressure relief portion and a weak portion disposed along the outer periphery of the pressure relief portion, the area of ​​the pressure relief portion being larger than the area of ​​the electrode lead-out holes.

[0037] Compared to the electrode lead-out holes, the pressure relief section can have a larger area, allowing for rapid release of internal temperature and pressure in the event of thermal runaway within the cylindrical battery cell. Conversely, the electrode lead-out holes can have a smaller area, reducing their impact on the wall strength, minimizing deformation of the portion of the wall near the electrode lead-out holes, and lowering the risk of electrode terminals detaching from the wall.

[0038] In some embodiments, the housing includes a housing and an end cap. The housing includes sidewalls and an end wall that are connected to each other. The sidewalls surround the electrode assembly. The end wall and the end cap are axially opposite each other along the cylindrical cell. The end cap is connected to the sidewalls, and the end wall is a wall portion.

[0039] In some embodiments, the electrode assembly further includes a second tab, which has the opposite polarity to the first tab. The second tab is electrically connected to the end wall. The end wall and the electrode terminal can serve as two electrodes of a cylindrical battery cell and are located on the same side of the cylindrical battery cell. When multiple cylindrical battery cells are assembled into a group, it facilitates the connection between the busbar and the end wall or the connection between the busbar and the electrode terminal, simplifying the structure of the battery device.

[0040] In some embodiments, a first tab is located at the end of the electrode assembly facing the end wall, and a second tab is located at the end of the electrode assembly facing the end cap. The cylindrical battery cell also includes a second current collector connected to the second tab; the second current collector is connected to at least one of the end cap and the side wall. Before thermal runaway of the cylindrical battery cell and actuation of the pressure relief mechanism, the side wall or end cap can restrain the electrode terminals through the second current collector, the electrode assembly, and the first current collector, reducing deformation of the wall portion during the increase of internal pressure in the cylindrical battery cell and reducing the risk of the electrode terminals detaching from the wall portion.

[0041] In some embodiments, the sidewall has an inwardly protruding convex portion, and the second current collector is connected to the convex portion. Connecting the second current collector to the convex portion can shorten the conductive path between the second tab and the wall portion, reduce resistance, reduce heat generation, and improve the cycle performance of the cylindrical battery cell.

[0042] In some embodiments, a portion of the second current collector is located on the side of the protrusion facing the end cap and is connected to the protrusion. The second current collector connects to the protrusion from the outside, which can reduce assembly difficulty.

[0043] In some embodiments, the height of the housing is 50 mm to 150 mm.

[0044] In some embodiments, the diameter of the cylindrical battery cell is 35 mm to 80 mm.

[0045] Secondly, embodiments of this application provide a battery device comprising a plurality of cylindrical battery cells provided in any of the embodiments of the first aspect.

[0046] Thirdly, embodiments of this application provide an electrical device including a battery device provided in any of the embodiments of the second aspect, the battery device being used to provide electrical energy. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0048] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0049] Figure 2 Schematic diagram of a battery device provided for some embodiments of this application;

[0050] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

[0051] Figure 4 This is a schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of this application;

[0052] Figure 5 for Figure 4 An exploded view of a cylindrical battery cell;

[0053] Figure 6 for Figure 4 A cross-sectional schematic diagram of a cylindrical battery cell shown;

[0054] Figure 7 A schematic diagram of the positive electrode sheet of a cylindrical battery cell provided in some embodiments of this application after being flattened;

[0055] Figure 8 for Figure 7 The diagram shows a cross-sectional view of the positive electrode along the CC direction;

[0056] Figure 9 for Figure 6 An enlarged view of box A;

[0057] Figure 10 This is a schematic diagram of the electrode terminals of a cylindrical battery cell provided in some embodiments of this application;

[0058] Figure 11 for Figure 10 Enlarged view of the area within the circle;

[0059] Figure 12 for Figure 6 Enlarged view at box B;

[0060] Figure 13 for Figure 12 Enlarged view of the area within the circle;

[0061] Figure 14 A partial cross-sectional schematic diagram of a cylindrical battery cell provided for other embodiments of this application;

[0062] Figure 15 This is a partial cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of this application.

[0063] The annotations in the attached figures are explained as follows:

[0064] 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing; 5b. Second housing; 6. Battery module; 7. Cylindrical battery cell;

[0065] 10. Electrode assembly; 10a. Electrode body; 10b. First tab; 10c. Second tab; 11. Positive electrode plate; 111. Positive current collector; 112. Positive electrode film;

[0066] 20. Outer shell; 20a. Wall portion; 21. Housing; 211. End wall; 211a. Electrode lead-out hole; 212. Side wall; 2121. Protrusion; 2122. Side wall recess; 2123. Press-fit portion; 22. End cap; 221. End cap recess;

[0067] 30. Electrode terminal; 31. Terminal body; 311. Recess; 311a. Bottom surface; 311b. Opening; 312. Connecting part; 313. Outer peripheral surface; 314. Third surface; 32. First limiting part; 321. First surface; 322. Second surface; 323. Overlapping part; 33. Second limiting part; 34. Transition part;

[0068] 40. First current collector; 50. First insulating component; 60. Protective component; 70. Pressure relief mechanism; 71. Pressure relief section; 72. Weak section; 80. Second current collector; 90. Cover plate; 91. Second insulating component; 92. Sealing component; 93. Third insulating component;

[0069] P, welded section; Z, axial direction. Detailed Implementation

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0075] 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.

[0076] In this application, "multiple" means two or more (including two).

[0077] Cylindrical battery cells can be rechargeable batteries, which are battery cells that can be recharged after discharge to activate the active materials and continue to be used.

[0078] A battery device can refer to a single physical module comprising one or more cylindrical battery cells to provide higher voltage and capacity.

[0079] A cylindrical battery cell typically includes a casing, electrode assembly, electrode terminals, and a pressure relief mechanism. The electrode assembly is housed within the casing, while the electrode terminals and pressure relief mechanism are located within the casing. The electrode terminals are electrically connected to the electrode assembly.

[0080] The pressure relief mechanism can be actuated to release internal pressure or temperature when the internal air pressure or temperature of the cylindrical battery cell reaches a predetermined threshold. By setting up the pressure relief mechanism, in the event of thermal runaway of the cylindrical battery cell, gas can be discharged from the channel formed by the pressure relief mechanism, thereby achieving directional pressure relief, reducing the risk of gas burning other components, and improving the reliability of the cylindrical battery cell and battery device.

[0081] In related technologies, electrode terminals are typically riveted to the housing. Recesses may be provided on the electrode terminals to locally thin them; during the assembly of cylindrical battery cells, the thinned portion of the electrode terminals can be welded from the outside of the housing to a component located inside the cylindrical battery cell to achieve electrical connection between the electrode terminals and the electrode assembly.

[0082] However, locally thinning the electrode terminals reduces their strength. When the internal pressure of a cylindrical battery cell increases dramatically due to thermal runaway, the thinned areas can cause the electrode terminals to deform and fail under pressure, leading to detachment from the casing and the formation of openings for gas release. This results in directional pressure relief failure of the cylindrical battery cell, affecting its reliability. In particular, to improve the fast-charging capability of cylindrical battery cells, the electrolyte may contain chain-like ester solvents; however, these solvents generate gas violently during thermal runaway, making it easier for the electrode terminals to detach from the casing.

[0083] In view of this, embodiments of this application provide a cylindrical battery cell, which includes a housing, an electrode assembly, a first current collector, and electrode terminals. The housing includes a wall portion with an electrode lead-out hole. The electrode assembly is housed within the housing, and the electrode assembly and the wall portion are arranged along the axial direction of the cylindrical battery cell. The electrode assembly includes a first tab. The first current collector is housed within the housing and electrically connected to the first tab. The electrode terminals are disposed on the wall portion, and each electrode terminal includes a terminal body and a first limiting portion. At least a portion of the terminal body is housed within the electrode lead-out hole, and at least one side of the terminal body along the axial direction has a recess. The terminal body includes a connecting portion corresponding to the bottom surface of the recess. The connecting portion is welded to the first current collector, and the first limiting portion is connected to the terminal body and protrudes from the outer peripheral surface of the terminal body. At least a portion of the first limiting portion is located along the axial direction on the side of the wall portion facing the electrode assembly, and the axial dimension of the first limiting portion is larger than the axial dimension of the connecting portion. Embodiments of this application can reduce the risk of the electrode terminals detaching from the housing in the event of thermal runaway of the cylindrical battery cell by increasing the thickness of the first limiting portion, thereby improving the reliability of the cylindrical battery cell.

[0084] The cylindrical battery cells described in this application are applicable to batteries and electrical devices that use batteries.

[0085] The electrical equipment disclosed in this application can be a device that uses a battery as a power source or various energy storage systems that use a battery as an energy storage element. The electrical equipment can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0086] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0087] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0088] like Figure 1 As shown, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0089] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0090] In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0091] Figure 2 A schematic diagram of a battery device provided for some embodiments of this application.

[0092] In some embodiments, the battery device 2 may include one or more battery cell assemblies for providing voltage and capacity.

[0093] A battery cell assembly may include multiple cylindrical battery cells ( Figure 2 (Not shown), multiple cylindrical battery cells are connected in series, parallel, or mixed series via a busbar. Mixed series refers to multiple cylindrical battery cells being connected in both series and parallel.

[0094] Cylindrical battery cells can be rechargeable battery cells. Rechargeable battery cells refer to cylindrical battery cells that can be recharged after being discharged to activate the active materials and continue to be used.

[0095] As an example, cylindrical battery cells can be lithium-ion battery cells, sodium-ion battery cells, sodium-lithium-ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium-sulfur battery cells, magnesium-ion battery cells, nickel-metal hydride battery cells, nickel-cadmium battery cells, lead-acid battery cells, etc.

[0096] In some embodiments, the battery cell assembly is typically formed by arranging multiple cylindrical battery cells; as an example, the battery cell assembly can be a battery module 6, which is formed by arranging and fixing multiple cylindrical battery cells to form an independent module.

[0097] In some embodiments, the battery device 2 may be a battery pack, which includes a housing 5 and one or more battery cell assemblies housed within the housing 5. As an example, the battery cell assembly may be a battery module 6, which can be housed within the housing by securing the battery module 6 to the housing. Alternatively, the battery cell assembly may be housed within the housing by directly securing multiple cylindrical battery cells to the housing.

[0098] In some embodiments, the housing 5 is used to house cylindrical battery cells, and the housing 5 can have various structures.

[0099] In some embodiments, the housing 5 may include a first housing 5a and a second housing 5b. The first housing 5a and the second housing 5b are fastened together to form a closed space inside the housing 5 to house the battery cell assembly. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first housing may be a top cover or a bottom plate.

[0100] In some embodiments, the housing 5 may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are respectively connected to the frame, forming an enclosed space inside the housing to accommodate individual battery cells. As an example, the frame may include multiple side beams.

[0101] In some embodiments, the housing 5 may be part of the vehicle's chassis structure. For example, a portion of the housing 5 may be at least a portion of the vehicle's floor, or a portion of the housing 5 may be at least a portion of the vehicle's crossbeams and longitudinal beams.

[0102] In some embodiments, the battery device 2 may be an energy storage device.

[0103] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0104] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0105] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

[0106] In some embodiments, such as Figure 3 As shown, there are multiple cylindrical battery cells 7. These multiple cylindrical battery cells 7 are first connected in series, parallel, or in a mixed manner to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or in a mixed manner to form a whole, which is housed in the casing.

[0107] Multiple cylindrical battery cells 7 in battery module 6 can be electrically connected through busbars to achieve parallel, series, or mixed connection of multiple cylindrical battery cells 7 in battery module 6. There can be one or more busbars, each used to electrically connect at least two cylindrical battery cells 7.

[0108] Figure 4 This is a schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of this application; Figure 5 for Figure 4 An exploded view of a cylindrical battery cell; Figure 6 for Figure 4 A cross-sectional schematic diagram of a cylindrical battery cell shown; Figure 7 A schematic diagram of the positive electrode sheet of a cylindrical battery cell provided in some embodiments of this application after being flattened; Figure 8 for Figure 7 The diagram shows a cross-sectional view of the positive electrode along the CC direction; Figure 9 for Figure 6 An enlarged view of box A; Figure 10 This is a schematic diagram of the electrode terminals of a cylindrical battery cell provided in some embodiments of this application; Figure 11 for Figure 10 Enlarged view of the area within the circle; Figure 12 for Figure 6 Enlarged view at box B; Figure 13 for Figure 12 Enlarged view of the area within the circle.

[0109] Reference Figures 4 to 13 This application provides a cylindrical battery cell 7, which includes a housing 20 and an electrode assembly 10, with at least a portion of the electrode assembly 10 housed within the housing 20.

[0110] The outer casing 20 is a hollow structure, forming an internal space for accommodating the electrode assembly 10 and the electrolyte. The outer casing 20 of the cylindrical battery cell 7 is cylindrical.

[0111] As an example, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening and the end cap 22 for closing the opening.

[0112] The housing 21 is a component used to fit the end cap 22 to form the internal cavity of the cylindrical battery cell 7. The formed internal cavity can be used to accommodate the electrode assembly 10, the electrolyte, and other components.

[0113] The housing 21 and the end cap 22 can be separate components. For example, an opening can be provided on the housing 21, and the end cap 22 can be used to close the opening to form an internal cavity for the cylindrical battery cell 7.

[0114] The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0115] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 can be the same as or different from the material of the housing 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when subjected to compression and impact, so that the cylindrical battery cell 7 can have higher structural strength and improve reliability.

[0116] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0117] The housing 21 may be open at one end or open at both ends. In some examples, the housing 21 may be a structure with an opening on one side, and one end cap 22 is provided to cover the housing 21. In other examples, the housing 21 may also be a structure with openings on both sides, and two end caps 22 are provided, with the two end caps 22 respectively covering the two openings of the housing 21.

[0118] In some embodiments, the housing 21 includes an end wall 211 and a side wall 212, the end wall 211 being disposed opposite to the end cap 22, and the side wall 212 surrounding the end wall 211 and connecting the end wall 211 and the end cap 22. Optionally, the end wall 211 and the side wall 212 are integrally formed.

[0119] Electrode assembly 10 is the component in the cylindrical battery cell 7 where the electrochemical reaction takes place. The housing 21 may contain one or more electrode assemblies 10.

[0120] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) are inserted and extracted back and forth between the positive and negative electrodes.

[0121] In some embodiments, the positive electrode may be a positive electrode sheet 11, which may include a positive current collector 111 and a positive electrode film layer 112 disposed on at least one surface of the positive current collector 111.

[0122] As an example, the positive current collector 111 has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer 112 is disposed on either or both of the two opposite surfaces of the positive current collector 111.

[0123] As an example, the positive current collector 111 can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0124] As an example, the positive electrode film 112 includes a positive electrode active material, which 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 oxides 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 LiNi 0.9 Co 0.05 Mn 0.05 O2, lithium nickel cobalt aluminum oxide (such as LiNi)0.80 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

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

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

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

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

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

[0130] As an example, the negative electrode film layer includes a negative electrode active material. 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. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material 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 negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0131] In some embodiments, the positive current collector 111 can be made of aluminum, and the negative current collector can be made of copper.

[0132] In some embodiments, the electrode assembly 10 further includes a separator disposed between the positive and negative electrodes. The separator serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0133] In some embodiments, the separator is a separator membrane. Any known porous separator membrane with good chemical and mechanical stability can be selected from the embodiments of this application.

[0134] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can 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 can be the same or different. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

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

[0136] In some embodiments, the cylindrical battery cell 7 also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The type of electrolyte can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0137] Liquid electrolytes include electrolyte salts and solvents.

[0138] In some embodiments, the electrolyte salt may be selected from 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.

[0139] In some embodiments, the solvent may be selected from at least one of 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 of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0140] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0141] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0142] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0143] As an example, inorganic solid electrolytes can be 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 phosphorus sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0144] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0145] In some embodiments, the electrode assembly 10 is a wound structure. Exemplarily, the positive electrode 11 and the negative electrode are wound into a cylindrical wound structure.

[0146] In some embodiments, the electrode assembly 10 includes an electrode body 10a, a first tab 10b, and a second tab 10c, wherein the first tab 10b and the second tab 10c are connected to the electrode body 10a.

[0147] The first electrode 10b and the second electrode 10c have opposite polarities. One of the first electrode 10b and the second electrode 10c is a positive electrode, and the other is a negative electrode.

[0148] As an example, the electrode body 10a includes a positive electrode film layer 112, a portion of the positive electrode current collector 111 covered by the positive electrode film layer 112, a negative electrode film layer, a portion of the negative electrode current collector covered by the negative electrode film layer, and a separator. The portion of the positive electrode current collector 111 not covered by the positive electrode film layer 112 includes a positive electrode tab, and the portion of the negative electrode current collector not covered by the negative electrode film layer includes a negative electrode tab. During the charging and discharging process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte.

[0149] Along the axial direction Z of the cylindrical battery cell 7, the first tab 10b and the second tab 10c can be disposed at the same end of the electrode assembly 10, or they can be disposed at opposite ends of the electrode assembly 10.

[0150] In some embodiments, the first tab 10b is wound into multiple turns. Optionally, the first tab 10b is formed into a cylindrical structure by a flattening or smoothing process.

[0151] In some embodiments, the second electrode 10c is wound into multiple turns. Optionally, the second electrode 10c is formed into a cylindrical structure by a flattening or smoothing process.

[0152] In some embodiments, the cylindrical battery cell 7 includes a housing 20, an electrode assembly 10, a first current collector 40, and an electrode terminal 30. The housing 20 includes a wall portion 20a, which has an electrode lead-out hole 211a. The electrode assembly 10 is housed within the housing 20, and the electrode assembly 10 and the wall portion 20a are arranged along the axial direction Z of the cylindrical battery cell 7. The electrode assembly 10 includes a first tab 10b. The first current collector 40 is housed within the housing 20 and electrically connected to the first tab 10b. The electrode terminal 30 is disposed on the wall portion 20a. The electrode terminal 30 includes a terminal body 31 and a first limiting portion 32. At least a portion of the terminal body 31 is housed within the electrode lead-out hole 211a. The terminal body 31 has a recess 311 on at least one side along the axial direction Z, and the terminal body 31 includes a connecting portion 312 corresponding to the bottom surface 311a of the recess 311. The connecting portion 312 is welded to the first current collector 40. The first limiting portion 32 is connected to the terminal body 31 and protrudes from the outer peripheral surface 313 of the terminal body 31. At least a portion of the first limiting portion 32 is located along the axial direction Z on the side of the wall portion 20a facing the electrode assembly 10, and the dimension of the first limiting portion 32 along the axial direction Z is larger than the dimension of the connecting portion 312 along the axial direction Z.

[0153] As an example, the wall portion 20a can be either an end cap 22 or an end wall 211.

[0154] The electrode lead-out hole 211a penetrates the wall portion 20a. As an example, along the axial direction Z, the electrode lead-out hole 211a penetrates the wall portion 20a.

[0155] As an example, the electrode lead-out hole 211a can be a round hole, a square hole, a racetrack-shaped hole, an elliptical hole, or a hole of other shapes.

[0156] The first electrode 10b can be either a positive electrode or a negative electrode.

[0157] The first current collector 40 can be connected to the first tab 10b by welding, bonding, crimping or other means to achieve electrical connection between the first current collector 40 and the first tab 10b. As an example, the first current collector 40 is welded to the first tab 10b.

[0158] In some examples, the terminal body 31 has a recess 311 on the side away from the electrode assembly 10 along the axial direction Z, and the connecting part 312 is the part of the terminal body 31 along the axial direction Z that corresponds to the bottom surface 311a of the recess 311; in this example, in the same plane perpendicular to the axial direction Z, the orthographic projection of the connecting part 312 completely coincides with the orthographic projection of the bottom surface 311a of the recess 311.

[0159] In other examples, the terminal body 31 has a recess 311 on the side of the electrode assembly 10 along the axial direction Z, and the connecting part 312 is the part of the terminal body 31 along the axial direction Z that corresponds to the bottom surface 311a of the recess 311; in this example, in the same plane perpendicular to the axial direction Z, the orthographic projection of the connecting part 312 completely coincides with the orthographic projection of the bottom surface 311a of the recess 311.

[0160] In some other examples, the terminal body 31 has a recess 311 on the side away from the electrode assembly 10 along the axial direction Z, and the terminal body 31 also has a recess 311 on the side closer to the electrode assembly 10 along the axial direction Z; the connecting part 312 is the part of the terminal body 31 located between the bottom surfaces 311a of the two recesses 311 along the axial direction Z.

[0161] At least a portion of the outer peripheral surface 313 of the terminal body 31 is accommodated in the electrode lead-out hole 211a. As an example, the outer peripheral surface 313 of the terminal body 31 may be a cylindrical surface, such as a cylindrical surface.

[0162] In some examples, the first limiting part 32 and the terminal body 31 can be integrally formed. In other examples, the first limiting part 32 and the terminal body 31 are formed independently and connected by welding, riveting, bonding or other means.

[0163] There may be one or more first limiting portions 32. In some examples, there is one first limiting portion 32, and the first limiting portion 32 surrounds the terminal body 31; in other examples, there are multiple first limiting portions 32, and the multiple first limiting portions 32 are arranged at intervals along the circumference of the terminal body 31.

[0164] The first limiting part 32 can be connected to the outer peripheral surface 313 of the terminal body 31; correspondingly, the first limiting part 32 can cover a part of the outer peripheral surface 313 of the terminal body 31.

[0165] As an example, in the radial direction of the cylindrical battery cell 7, the first limiting portion 32 protrudes from the outer peripheral surface 313 of the terminal body 31.

[0166] In the same plane perpendicular to the axis Z, at least a portion of the orthographic projection of the first limiting portion 32 lies within the orthographic projection of the wall portion 20a.

[0167] As an example, the thickness direction of the first limiting portion 32 may be parallel to the axial direction Z, and the dimension of the first limiting portion 32 along the axial direction Z may be the thickness of the first limiting portion 32. The thickness direction of the connecting portion 312 may be parallel to the axial direction Z, and the dimension of the connecting portion 312 along the axial direction Z may be the thickness of the first limiting portion 32.

[0168] During the assembly of the cylindrical battery cell 7, the connecting portion 312 and the first current collector 40 can be welded from the outside of the connecting portion 312, thereby reducing the risk of weld slag sputtering into the casing 20. By providing the recess 311, the dimension of the connecting portion 312 along the axial direction Z can be reduced, thereby reducing the power required to weld the connecting portion 312 and the first current collector 40, reducing welding heat generation, and reducing the risk of burning the electrode assembly 10. In the application embodiment, the dimension of the first limiting portion 32 along the axial direction Z is set to be larger than the dimension of the connecting portion 312 along the axial direction Z, which can improve the structural strength of the first limiting portion 32. Even if the recess 311 reduces the strength of the terminal body 31, the first limiting portion 32 can resist the large internal gas pressure in the event of thermal runaway of the cylindrical battery cell 7, thereby reducing the bending deformation of the first limiting portion 32, reducing the possibility of cracking at the connection between the first limiting portion 32 and the terminal body 31, reducing the risk of the electrode terminal 30 detaching from the wall portion 20a, which is beneficial for directional pressure relief of the cylindrical battery cell 7 and improving the reliability of the cylindrical battery cell 7.

[0169] In some embodiments, the connecting portion 312 can be connected to the first current collector 40 by laser welding.

[0170] In some embodiments, the first limiting portion 32 has a first surface 321 and a second surface 322 disposed opposite each other along the axial direction Z; in the axial direction Z, the first surface 321 is closer to the wall portion 20a than the second surface 322. The distance between the first surface 321 and the second surface 322 along the axial direction Z can be the thickness of the first limiting portion 32. As an example, both the first surface 321 and the second surface 322 are planar.

[0171] In some embodiments, the ratio α of the dimension T1 of the first limiting portion 32 along the axial direction Z to the dimension T2 of the connecting portion 312 along the axial direction Z is 1.1-3.6.

[0172] As an example, α is 1.1, 1.2, 1.4, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.5, 2.6, 2.8, 3.0, 3.2, 3.4, 3.5, or 3.6.

[0173] In this embodiment, α is set to be greater than or equal to 1.1, which gives the first limiting part 32 higher structural strength. This reduces the risk of the electrode terminal 30 detaching from the wall 20a during thermal runaway of the cylindrical battery cell 7, while ensuring that the dimensions of the connecting part 312 meet the external welding requirements, thereby improving the reliability of the cylindrical battery cell 7. In this embodiment, α is set to be less than or equal to 4.5 to reduce the space occupied by the first limiting part 32 in the axial Z direction and reduce the risk of the connecting part 312 cracking under internal gas pressure.

[0174] In some embodiments, α is 1.5-3.

[0175] In some embodiments, the dimension T2 of the connecting portion 312 along the axial direction Z is 0.5mm-1.0mm.

[0176] As an example, T2 is 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1.0mm.

[0177] In this embodiment, the dimension of the connecting portion 312 along the axial direction Z is set to be greater than or equal to 0.5 mm to reduce the risk of the connecting portion 312 melting through during welding, improve welding quality, and reduce the deformation of the connecting portion 312 during thermal runaway of the cylindrical battery cell 7. The connecting portion 312 is welded to the first current collector 40 to form a welded portion P. In this embodiment, the dimension of the connecting portion 312 along the axial direction Z is set to be greater than or equal to 0.5 mm to give the connecting portion 312 a certain strength, thereby reducing the risk of cracking at the junction of the connecting portion 312 and the welded portion P under internal gas pressure, which is beneficial to achieving directional pressure relief of the cylindrical battery cell 7. In this embodiment, the dimension of the connecting portion 312 along the axial direction Z is set to be less than or equal to 1 mm to reduce the welding power requirements, reduce the heat conducted to the electrode assembly 10, and reduce the risk of the electrode assembly 10 being burned.

[0178] In some embodiments, T2 is 0.7mm-0.8mm.

[0179] In some embodiments, the dimension T1 of the first limiting portion 32 along the axial direction Z is 1.1mm-1.8mm.

[0180] For example, T1 is 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm or 1.8mm.

[0181] In this embodiment, the dimension of the first limiting portion 32 along the axial direction Z is set to be greater than or equal to 1.1 mm, so that the first limiting portion 32 has high structural strength and reduces the risk of the electrode terminal 30 detaching from the wall portion 20a in the event of thermal runaway of the cylindrical battery cell 7. In this embodiment, the dimension of the first limiting portion 32 along the axial direction Z is set to be less than or equal to 1.8 mm, which can reduce the space occupied by the first limiting portion 32 in the axial direction Z and reduce the impact on the energy density of the cylindrical battery cell 7.

[0182] In some embodiments, T1 is 1.2mm-1.5mm.

[0183] In some embodiments, the electrode terminal 30 further includes a second limiting portion 33, which is connected to the terminal body 31 and protrudes from the outer peripheral surface 313 of the terminal body 31. Along the axial direction Z, a portion of the wall portion 20a is located between the first limiting portion 32 and the second limiting portion 33.

[0184] In some examples, the second limiting part 33 and the terminal body 31 can be integrally formed. In other examples, the second limiting part 33 and the terminal body 31 are formed independently and connected by welding, riveting, bonding or other means.

[0185] The first limiting part 32 may be located inside the wall part 20a, and the second limiting part 33 may be located outside the wall part 20a.

[0186] The dimension of the first limiting part 32 along the axial direction Z can be greater than, equal to or less than the dimension of the second limiting part 33 along the axial direction Z.

[0187] In the embodiments of this application, by providing the first limiting part 32 and the second limiting part 33, the electrode terminal 30 and the wall part 20a can be relatively fixed in the axial Z direction.

[0188] In some embodiments, the size of the first limiting portion 32 is larger than the size of the second limiting portion 33 in the axial direction Z.

[0189] The first limiting part 32 has a larger dimension in the axial Z direction, which results in less deformation during thermal runaway of the cylindrical battery cell 7, thereby reducing the risk of the electrode terminal 30 detaching from the wall portion 20a during thermal runaway of the cylindrical battery cell 7. The second limiting part 33 has a smaller dimension in the axial Z direction, which makes it easier to deform during the assembly of the electrode terminal 30, thus reducing the difficulty of riveting the electrode terminal 30 to the wall portion 20a.

[0190] In some embodiments, in the radial direction of the cylindrical battery cell 7, the first limiting portion 32 protrudes from the outer peripheral surface 313 by a dimension L1 that is greater than the second limiting portion 33 protruding from the outer peripheral surface 313 by a dimension L2.

[0191] The first limiting part 32 has a larger radial dimension, and the overlapping area between the first limiting part 32 and the wall part 20a in the axial Z direction is larger, which helps to reduce the risk of the electrode terminal 30 detaching from the wall part 20a in the event of thermal runaway of the cylindrical battery cell 7. The second limiting part 33 has a smaller radial dimension, and it is easier to deform during the assembly of the electrode terminal 30 and easier to form by folding, which helps to reduce the difficulty of riveting the electrode terminal 30 to the wall part 20a.

[0192] In some embodiments, the ratio of the dimension L1 of the first limiting portion 32 protruding from the outer peripheral surface 313 to the dimension L2 of the second limiting portion 33 protruding from the outer peripheral surface 313 is greater than or equal to 2.

[0193] As an example, L1 / L2 can be 2, 2.5, 3, 3.5, or 4.

[0194] The connection strength between the wall portion 20a and the electrode terminal 30 is positively correlated with L2. Under the premise that the connection strength between the wall portion 20a and the electrode terminal 30 meets the requirements, setting L1 / L2 to be greater than or equal to 2 can further improve the structural strength of the first limiting portion 32 and reduce the risk of the electrode terminal 30 detaching from the wall portion 20a when the cylindrical battery cell 7 experiences thermal runaway.

[0195] In some embodiments, the cylindrical battery cell 7 further includes a first insulating member 50 surrounding the terminal body 31. In the axial direction Z, at least a portion of the first insulating member 50 is located between the second limiting portion 33 and the wall portion 20a.

[0196] The first insulating member 50 can insulate and isolate the second limiting part 33 from the wall part 20a, thereby reducing the risk of the wall part 20a becoming conductive with the electrode terminal 30.

[0197] In some embodiments, the cylindrical battery cell 7 further includes protective members 60, all of which surround the terminal body 31. In the axial direction Z, at least a portion of the first insulating member 50 is located between the protective member 60 and the wall portion 20a, and at least a portion of the protective member 60 is located between the first insulating member 50 and the second limiting portion 33. The tensile strength of the protective member 60 is greater than the tensile strength of the first insulating member 50.

[0198] Tensile strength reflects a material's resistance to fracture. It is the ability of a material or specimen to resist fracture under static tension, or the maximum tensile force (tensile stress) that a material can withstand without fracturing.

[0199] For example, the tensile strength of the protective component 60 can be tested as follows: cut a section of specimen from the protective component and measure the cross-sectional area S of the specimen; fix both ends of the specimen to a tensile testing machine; start the tensile testing machine and load it at a constant speed, recording the maximum load F at which the specimen fails in shear; calculate F / S, and the tensile strength of the protective component 50 can be measured. Detailed steps can be found in the national standard GB / T 228-2002 "Metallic materials - Tensile testing at room temperature".

[0200] Similarly, the tensile strength of the first insulating component can also be tested using the method described above.

[0201] The protective component 60 surrounds the outer periphery of the terminal body 31. During the production or use of the cylindrical battery cell 7, the protective component 60 can limit the degree of deformation and movement of the terminal body 31 in its radial direction, thereby reducing the deformation of the first insulating component 50 under the force of the terminal body 31, reducing the risk of cracking of the first insulating component 50, and improving the reliability of the cylindrical battery cell 7. Compared with the first insulating component 50, the protective component 60 has higher tensile strength and is less prone to deformation and cracking when subjected to the force of the terminal body 31, thereby reducing the risk of failure of the protective component 60 and improving the reliability of the cylindrical battery cell 7.

[0202] In some embodiments, the tensile strength of the protective member 60 is greater than the tensile strength of the electrode terminal 30. The protective member 60 can restrain the terminal body 31 and reduce the deformation of the terminal body 31.

[0203] In some embodiments, the tensile strength of the protective member 60 is greater than or equal to 150 MPa. Optionally, the tensile strength of the protective member 60 is 150 MPa, 200 MPa, 300 MPa, 500 MPa, 600 MPa, 800 MPa, or 1000 MPa.

[0204] In some embodiments, the elastic modulus of the protective member 60 is 50 GPa-500 GPa to reduce the deformation of the protective member 60 when it is squeezed by the terminal body 31.

[0205] In some embodiments, the protective element 60 is made of metal or ceramic. Metals and ceramics have high tensile strength, which can improve the reliability of the protective element 60 and reduce the risk of cracking.

[0206] In some embodiments, the protective member 60 is made of aluminum or stainless steel. For example, the protective member 60 is an aluminum ring or a stainless steel ring.

[0207] In some embodiments, the protective element 60 is made of insulating ceramic, which can improve the insulation between the electrode terminal 30 and the wall portion 20a and reduce the risk of short circuit.

[0208] In some embodiments, the electrode terminal 30 further includes a transition portion 34, which surrounds the terminal body 31 and is connected to the outer peripheral surface 313. The transition portion 34 is located on one side of the first limiting portion 32 along the axial direction Z and is connected to the first limiting portion 32. In the radial direction of the cylindrical battery cell 7, the first limiting portion 32 protrudes outward from the transition portion 34.

[0209] The transition portion 34 can be located on the side of the first limiting portion 32 facing the wall portion 20a along the axial direction Z, or it can be provided on the side of the first limiting portion 32 facing away from the wall portion 20a along the axial direction Z.

[0210] During thermal runaway of the cylindrical battery cell 7, the terminal body 31 is subjected to the internal air pressure of the cylindrical battery cell 7. Under the action of the wall portion 20a and the terminal body 31, the first limiting portion 32 near the root of the terminal body 31 is subjected to greater stress. The transition portion 34 connects the first limiting portion 32 and the terminal body 31. It can disperse stress, reduce the bending deformation of the first limiting portion 32, reduce the risk of cracking at the root of the first limiting portion 32 and the risk of the electrode terminal 30 detaching from the wall portion 20a, and improve the reliability of the cylindrical battery cell 7.

[0211] In some embodiments, the dimension of the transition portion 34 gradually decreases along the axial direction Z in a direction away from the terminal body 31.

[0212] The smooth dimension change of the transition portion 34 along the axial direction Z helps to disperse stress, reduce the risk of root cracking of the first limiting portion 32 and the risk of electrode terminal 30 detaching from the wall portion 20a, and improve the reliability of the cylindrical battery cell 7.

[0213] In some embodiments, the maximum dimension L3 of the transition portion 34 along the axial direction Z is 0.1 mm to 0.8 mm.

[0214] As an example, L3 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm or 0.8mm.

[0215] As an example, L3 can be equal to the axial Z dimension at the connection between the transition portion 34 and the terminal body 31.

[0216] In this embodiment, the maximum dimension of the transition portion 34 along the axial direction Z is set to be greater than or equal to 0.1 mm to improve the strength of the transition portion 34 and reduce the risk of cracking. In this embodiment, the maximum dimension of the transition portion 34 along the axial direction Z is set to be less than or equal to 0.8 mm to reduce the impact of the transition portion 34 on the energy density of the cylindrical battery cell 7.

[0217] In some embodiments, the dimension L4 of the transition portion 34 along the radial direction of the cylindrical battery cell 7 is 0.1 mm to 0.8 mm.

[0218] As an example, L4 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm or 0.8mm.

[0219] In this embodiment, the radial dimension of the transition portion 34 is set to be greater than or equal to 0.1 mm to improve the strength of the transition portion 34 and reduce the risk of cracking. In this embodiment, the maximum radial dimension of the transition portion is set to be less than or equal to 0.8 mm to reduce the impact of the transition portion 34 on the energy density of the cylindrical battery cell 7.

[0220] In some embodiments, L3 is equal to L4.

[0221] In some embodiments, the outer surface of the transition portion 34 is a rounded corner surface, which connects the first surface 321 and the outer peripheral surface 313. The radius of the rounded corner surface is 0.1mm-0.8mm. Optionally, the rounded corner surface is tangent to the first surface 321.

[0222] In other embodiments, the outer surface of the transition portion 34 is a chamfered surface, the chamfered surface and the first surface 321 are at an angle of 45°, and the dimension of the chamfered surface along the axial direction Z is 0.1mm-0.8mm.

[0223] In some embodiments, L3 is 0.3mm-0.5mm and L4 is 0.3mm-0.5mm.

[0224] In some embodiments, in the axial direction Z, the transition portion 34 is located on the side of the first limiting portion 32 facing away from the electrode assembly 10.

[0225] When the cylindrical battery cell 7 experiences thermal runaway, the first limiting portion 32 is subjected to a tensile force on the side facing away from the electrode assembly 10. In this embodiment, the transition portion 34 is disposed on the side of the first limiting portion 32 facing away from the electrode assembly 10, which can disperse the tensile force on the root of the first limiting portion 32, reduce the risk of cracking at the root of the first limiting portion 32 and the risk of the electrode terminal 30 detaching from the wall portion 20a, and improve the reliability of the cylindrical battery cell 7.

[0226] In some embodiments, the orthographic projection of the transition portion 34 lies within the orthographic projection of the electrode lead-out hole 211a in the same plane perpendicular to the axial direction Z. This embodiment of the application can reduce the risk of the transition portion 34 making contact and conducting with the wall portion 20a.

[0227] In some embodiments, the first limiting portion 32 includes an overlapping portion 323, the orthographic projection of which lies within the projection of the wall portion 20a in the same plane perpendicular to the axial direction Z.

[0228] The overlapping portion 323 is the portion of the first limiting portion 32 that overlaps with the wall portion 20a in the axial direction Z.

[0229] In the event of thermal runaway of the cylindrical battery cell 7, the overlapping portion 323 is constrained by the wall portion 20a to reduce the risk of the electrode terminal 30 coming out of the housing 20 through the electrode lead-out hole 211a.

[0230] In some embodiments, the connecting portion 312 is circular, the overlapping portion 323 is annular, and the annular width W of the overlapping portion 323 is greater than or equal to the radius of the connecting portion 312.

[0231] The ring width W of the overlapping portion 323 can be the difference between the outer radius and the inner radius of the overlapping portion 323.

[0232] The larger the radius of the connecting portion 312, the lower the strength of the terminal body 31, and the higher the risk of deformation of the terminal body 31 during thermal runaway of the cylindrical battery cell 7. The larger the circumferential width W of the overlapping portion 323, the larger the area of ​​the electrode terminal 30 constrained by the wall portion 20a, and the lower the risk of the electrode terminal 30 detaching from the wall portion 20a. In the embodiments of this application, the circumferential width W of the overlapping portion 323 is designed according to the radius of the connecting portion 312, which can reduce the risk of the electrode terminal 30 detaching from the wall portion 20a.

[0233] In some embodiments, the housing 20 includes a sidewall 212 surrounding the electrode assembly 10, and a wall portion 20a connecting to the sidewall 212. At least a portion of the wall portion 20a has a thickness greater than the thickness of the sidewall 212.

[0234] By employing a sidewall 212 with a smaller thickness, the internal space of the outer casing 20 can be increased, thereby improving the energy density of the cylindrical battery cell 7. By increasing the thickness of at least a portion of the wall portion 20a, the deformation resistance of the wall portion 20a can be improved; in the event of thermal runaway of the cylindrical battery cell 7, the deformation of the wall portion 20a under internal gas pressure is smaller, which can constrain the first limiting portion 32, thereby reducing the risk of the electrode terminal 30 detaching from the wall portion 20a.

[0235] In some embodiments, the thickness T3 of the wall portion 20a is 0.4 mm to 1.2 mm.

[0236] As an example, the thickness of the wall portion 20a is 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm or 1.2 mm.

[0237] In this embodiment, the thickness of the wall portion 20a is set to be greater than or equal to 0.4 mm to reduce the deformation of the wall portion 20a during thermal runaway of the cylindrical battery cell 7, thereby reducing the risk of the electrode terminal 30 detaching from the wall portion 20a. In this embodiment, the thickness of the wall portion 20a is set to be less than or equal to 1.2 mm to reduce the impact of the wall portion 20a on the energy density of the cylindrical battery cell 7.

[0238] In some embodiments, T3 is 0.7mm-1.2mm.

[0239] In some embodiments, the tensile strength of the first limiting portion 32 is 125MPa-190MPa.

[0240] As an example, the tensile strength of the first limiting part 32 is 125MPa, 128MPa, 130MPa, 140MPa, 150MPa, 160MPa, 170MPa, 180MPa or 190MPa.

[0241] The tensile strength of the first limiting part 32 can be measured with reference to the national standard GB / T 228-2002 "Metallic materials - Tensile testing at room temperature".

[0242] By employing a first limiting part 32 with high tensile strength, the ability of the first limiting part 32 to resist deformation can be enhanced, reducing the risk of the electrode terminal 30 detaching from the wall part 20a.

[0243] In some embodiments, the electrode terminal 30 is made of aluminum or an aluminum alloy. Optionally, the electrode terminal 30 is made of 1060H18 aluminum alloy or ternary aluminum. 1060H18 aluminum alloy or ternary aluminum has high tensile strength.

[0244] In some embodiments, the diameter of the cylindrical battery cell 7 is D. The diameter of the first limiting portion 32 is D1, where 0.65 ≤ D1 / D ≤ 0.80.

[0245] As an example, D1 / D can be 0.65, 0.66, 0.68, 0.70, 0.72, 0.74, 0.75, 0.76, 0.78, or 0.80.

[0246] The first limiting part 32 can be an annular shape, and the outer diameter of the first limiting part 32 is D1.

[0247] In this embodiment, setting D1 / D to greater than or equal to 0.65 increases the area of ​​the first limiting portion 32 constrained by the wall portion 20a, reducing the risk of the electrode terminal 30 detaching from the wall portion 20a. In this embodiment, setting D1 / D to less than or equal to 0.8 reduces the impact of the first limiting portion 32 on the energy density of the cylindrical battery cell 7 and provides space for other components within the casing 20.

[0248] In some embodiments, D1 is 30mm-36mm. As an example, D1 is 30mm, 31mm, 32mm, 33mm, 34mm, 35mm or 36mm.

[0249] In some embodiments, the diameter of the cylindrical battery cell 7 is D. The diameter of the terminal body 31 is D2, where 0.30 ≤ D2 / D ≤ 0.50;

[0250] As an example, D² / D can be 0.30, 0.32, 0.34, 0.35, 0.36, 0.38, 0.40, 0.42, 0.44, 0.45, 0.46, 0.48, or 0.50.

[0251] In this embodiment, D2 / D is set to be greater than or equal to 0.30 to increase the current-carrying area of ​​the terminal body 31 and reduce the heat generation of the electrode terminal 30 during charging and discharging. In this embodiment, D2 / D is set to be less than or equal to 0.50, which can reduce the diameter of the electrode lead-out hole 211a, reduce the impact on the strength of the wall portion 20a, reduce the deformation of the wall portion 20a during thermal runaway of the cylindrical battery cell 7, and reduce the risk of the electrode terminal 30 detaching from the wall portion 20a.

[0252] In some embodiments, the terminal body 31 is cylindrical. The outer peripheral surface 313 of the terminal body 31 is a cylindrical surface.

[0253] In some embodiments, D2 is 13mm-23mm. As an example, D2 is 13mm, 13.5mm, 14mm, 14.5mm, 15mm, 15.5mm, 16mm, 16.5mm, 17mm, 17.5mm, 18mm, 18.5mm, 19mm, 19.5mm, 20mm, 20.5mm, 21mm, 21.5mm, 22mm, 22.5mm or 23mm.

[0254] In some embodiments, D2 is 15mm-21mm. Optionally, D2 is 18mm-19mm.

[0255] In some embodiments, the diameter of the cylindrical battery cell 7 is D, the diameter of the connecting portion 312 is D3, and 0.10≤D3 / D≤0.25.

[0256] As an example, D3 / D can be 0.10, 0.12, 0.15, 0.18, 0.20, 0.22, 0.24, or 0.25.

[0257] In this embodiment, D3 / D is set to be greater than or equal to 0.1, which reduces the difficulty of welding the connecting part 312 to the first current collector 40, increases the welding area between the connecting part 312 and the first current collector 40, and improves the connection strength and current flow area between the connecting part 312 and the first current collector 40. In this embodiment, D3 / D is set to be less than or equal to 0.25 to reduce the impact of the recess 311 on the strength of the terminal body 31 and reduce the deformation of the terminal body 31 during thermal runaway of the cylindrical battery cell 7.

[0258] In some embodiments, D3 can be 4.5mm-11.5mm. As an example, D3 can be 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, 10.5mm, 11mm or 11.5mm.

[0259] In some embodiments, the electrode terminal 30 does not have an injection hole that penetrates the connection portion 312. During the production process of the cylindrical battery cell 7, it is not necessary to inject electrolyte into the housing 20 through the electrode terminal 30. The absence of an injection hole in the connection portion 312 reduces the impact of the injection hole on the strength of the connection portion 312 and minimizes the deformation of the terminal body 31 during thermal runaway of the cylindrical battery cell 7.

[0260] In some embodiments, the recess 311 is provided on the side of the terminal body 31 facing away from the electrode assembly 10. In this embodiment, the first current collector 40 does not need to extend into the recess 311 to contact the connection portion 312, which helps to simplify the structure of the first current collector 40.

[0261] In some embodiments, the terminal body 31 has a third surface 314 facing the electrode assembly 10, and the third surface 314 may be coplanar with the second surface 322. Optionally, the surface of the connection portion 312 facing the electrode assembly 10 constitutes a part of the third surface 314.

[0262] In some embodiments, an opening 311b is formed on the side of the recess 311 away from the connecting portion 312. The ratio of the diameter D4 of the opening 311b to the diameter D2 of the terminal body 31 is 0.3-0.6.

[0263] In this embodiment, D4 / D2 is set to be greater than or equal to 0.3, which facilitates welding the connection part 312 and the first current collector 40 from the outside. In this embodiment, D4 / D2 is set to be less than or equal to 0.6, so as to reduce the impact of the recess 311 on the strength of the terminal body 31 and to allow the outer surface of the terminal body 31 to retain a larger area, which is beneficial to realize the connection between the terminal body 31 and the current collector.

[0264] In some embodiments, D4 is 7mm-9mm. As an example, D4 ​​is 7mm, 7.5mm, 8mm, 8.5mm or 9mm.

[0265] In some embodiments, the electrode terminal 30 is integrally formed. The integrally formed electrode terminal 30 has higher strength.

[0266] As an example, the electrode terminal 30 is configured to form a second limiting portion 33 by pressing the electrode terminal 30 after it passes through the electrode lead-out hole 211a from the inside of the wall portion 20a.

[0267] In some embodiments, the cylindrical battery cell includes a seal 92, at least a portion of which is clamped between a first limiting portion 32 and a wall portion 20a in the axial direction Z. The seal 92 can be used to seal electrode lead-out holes. The seal 92 surrounds the terminal body 31.

[0268] In some embodiments, the cylindrical battery cell further includes a third insulating member 93. At least a portion of the third insulating member 93 is held between the first limiting portion 32 and the wall portion 20a in the axial direction Z. The third insulating member 93 can be used to insulate the first limiting portion 32 from the wall portion 20a.

[0269] In some embodiments, the electrode assembly 10 includes a positive electrode 11, which includes a positive current collector 111 and a positive electrode film 112 disposed on at least one side of the positive current collector 111. The positive electrode film 112 includes a positive electrode active material, which includes a layered transition metal oxide. The layered transition metal oxide includes a material with the chemical formula Li. a Ni b Co c M d O e A f The compound and its modified compounds contain at least one of the following: 0.8≤a≤1.2, 0.8≤b≤0.95, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes at least one of N, F, S and Cl.

[0270] For example, b is 0.8, 0.82, 0.84, 0.85, 0.88, 0.9, 0.92, 0.94, or 0.95.

[0271] As an example, examples of layered transition metal oxides may include, but are not limited to, LiNi. 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 LiNi 0.9 Co 0.05 Mn 0.05 O2 (also known as Ni) 90 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.80 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0272] Cylindrical battery cells with high nickel content have advantages such as high energy density, good low-temperature performance, and good charge and discharge performance.

[0273] Specifically, the positive electrode film layer 112 has a higher nickel content, enabling it to store more electrical energy, thus significantly improving the energy density of the cylindrical battery cell 7. With the increase in nickel content, the amount of cobalt used is relatively reduced. Cobalt is a scarce and expensive metal; reducing cobalt usage lowers the cost of the cylindrical battery cell 7. The cylindrical battery cell 7 with a higher nickel content has higher conductivity, meaning it can operate at higher power, supporting fast charging and high-current discharge. In low-temperature environments, the capacity decay of the cylindrical battery cell 7 with a higher nickel content is relatively small, maintaining high discharge efficiency and allowing electrical equipment to operate normally in low-temperature conditions.

[0274] However, cylindrical battery cells 7 with high nickel content have relatively poor thermal stability, and they produce more gas during thermal runaway, resulting in a faster increase in internal gas pressure. This embodiment improves the bending resistance of the first limiting portion 32 by increasing its dimension along the Z-axis, reducing the likelihood of the electrode terminal 30 detaching from the wall portion 20a under internal gas pressure. This facilitates directional pressure relief of the cylindrical battery cells 7 with high nickel content, thereby improving their reliability.

[0275] In some embodiments, 0.8 ≤ b ≤ 0.95, and optionally, 0.85 ≤ b ≤ 0.90.

[0276] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte contained within the housing 20. The electrolyte comprises a chain ester solvent, wherein the chain ester solvent comprises 25.5 wt% to 76.5 wt% by mass in the electrolyte.

[0277] For example, the mass percentage of the chain ester solvent in the electrolyte is 25.5 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 32 wt%, 35 wt%, 38 wt%, 40 wt%, 42 wt%, 45 wt%, 48 wt%, 50 wt%, 52 wt%, 55 wt%, 58 wt%, 60 wt%, 62 wt%, 65 wt%, 68 wt%, 70 wt%, 72 wt%, 75 wt%, 76.5 wt%, or any range of two of the above values.

[0278] In this embodiment, the mass percentage of the chain-like ester solvent is greater than or equal to 25.5 wt%, resulting in a relatively high electrolyte conductivity. This is beneficial for improving the liquid-phase transport capability of active ions, enhancing the fast charging and discharging capability of the cylindrical battery cell 7, and thus improving the rate performance of the cylindrical battery cell 7. The mass percentage of the chain-like ester solvent is also greater than or equal to 25.5 wt%, which also results in a relatively low viscosity of the electrolyte system, making it easier to flow and wet the electrode assembly 10. This further improves the fast charging and discharging capability of the cylindrical battery cell 7, thereby enhancing its rate performance.

[0279] When the chain-like ester solvent decomposes and produces gas during thermal runaway of the cylindrical battery cell 7, the internal gas pressure of the cylindrical battery cell 7 increases rapidly due to the chain-like ester solvent having a mass percentage greater than or equal to 25.5 wt%. In this embodiment, the first limiting part 32 has high structural strength, and when the chain-like ester solvent decomposes and produces gas, the first limiting part 32 can also resist the internal gas pressure of the cylindrical battery cell 7, thereby reducing the risk of the electrode terminal 30 detaching from the wall 20a under internal gas pressure. This is beneficial for achieving directional pressure relief of the cylindrical battery cell 7 with a high chain-like ester solvent content and improving the reliability of the cylindrical battery cell 7.

[0280] Chain-like ester solvents may decompose and generate gas during the cyclic charge-discharge process of cylindrical battery cell 7. In this embodiment, the mass percentage of the chain-like ester solvent is set to less than or equal to 76.5 wt%, which can limit the internal gas pressure of the cylindrical battery cell 7, reduce the deformation of the outer casing 20, reduce the risk of failure of the cylindrical battery cell 7, and improve reliability. This embodiment can also limit the maximum internal gas pressure of the cylindrical battery cell 7 during thermal runaway, reducing the risk of the electrode terminals 30 detaching from the wall 20a under internal gas pressure.

[0281] In some embodiments, the chain ester solvent has a mass percentage content of 42.5 wt% to 70 wt% in the electrolyte, which can further balance the rate performance and reliability of the cylindrical battery cell 7 and improve the cycle performance of the cylindrical battery cell 7.

[0282] In some embodiments, the chain ester solvent includes at least one of chain carbonates and chain carboxylic esters.

[0283] In some embodiments, the chain ester solvent includes chain carbonates and chain carboxylic esters. The combined use of chain carboxylic esters and chain carbonates can improve the conductivity of the electrolyte, enhance the liquid phase transport kinetics of the electrolyte, and further improve the rate performance and reliability of the battery cells.

[0284] In some embodiments, the electrolyte further includes cyclic lipid solvents.

[0285] In some embodiments, the cylindrical battery cell 7 further includes a pressure relief mechanism 70 disposed on the housing 20, the pressure relief mechanism 70 being disposed on the side of the electrode assembly 10 away from the electrode terminal 30.

[0286] In this embodiment, the pressure relief mechanism 70 and the electrode terminal 30 are respectively disposed on both sides of the electrode assembly 10, which helps to reduce the impact on the electrode terminal 30 during pressure relief and reduce the risk of the electrode terminal 30 detaching from the wall 20a.

[0287] In some embodiments, the pressure relief mechanism 70 includes a pressure relief portion 71 and a weak portion 72 disposed along the outer periphery of the pressure relief portion 71.

[0288] The weak point 72 is a relatively weak part of the pressure relief mechanism 70, which is a part of the pressure relief mechanism 70 that is prone to breakage, fracture, tearing, or opening. For example, the strength of the pressure relief mechanism 70 is less than the strength of the portion of the pressure relief mechanism 70 near the weak point 72.

[0289] In some examples, embodiments of this application may create grooves, indentations, or other structures in a predetermined area of ​​the pressure relief mechanism 70 to reduce the local strength of the pressure relief mechanism 70, thereby forming a weak portion 72 on the pressure relief mechanism 70. For example, a thinning process may be performed on a predetermined area of ​​the pressure relief mechanism 70, and the thinned portion of the pressure relief mechanism 70 forms the weak portion 72. In other examples, the predetermined area of ​​the pressure relief mechanism 70 may be material-treated so that the strength of this area is weaker than the strength of other areas; in other words, this area is the weak portion 72.

[0290] The weak part 72 can rupture when the internal pressure or temperature of the cylindrical battery cell 7 reaches a threshold; the pressure relief part 71 can be the part of the pressure relief mechanism 70 used to form a pressure relief channel when the weak part 72 ruptures.

[0291] In some examples, the weak portion 72 may surround the pressure relief portion 71. In the event of thermal runaway of the cylindrical battery cell 7, the weak portion 72 is at least partially broken; for example, the weak portion 72 is completely broken, and the pressure relief portion 71 is detached from the casing 20, thereby forming a pressure relief channel; for example, the weak portion 72 is partially broken, and the pressure relief portion 71 is flipped outward under the internal pressure of the cylindrical battery cell 7 to form a pressure relief channel.

[0292] In other examples, the weak portion 72 may also partially surround the pressure relief portion 71. The line connecting the two ends of the weak portion 72 and the weak portion 72 together define the pressure relief portion 71. In the event of thermal runaway of the cylindrical battery cell 7, the weak portion 72 ruptures, and the pressure relief portion 71 can be rotated outward about the line connecting the two ends of the weak portion 72 under the action of the internal pressure of the cylindrical battery cell 7 to form a pressure relief channel.

[0293] In some embodiments, the area of ​​the pressure relief portion 71 is larger than the area of ​​the electrode lead-out hole 211a.

[0294] For example, the area of ​​the electrode lead-out hole 211a can be the area of ​​the smallest cross-section of the electrode lead-out hole 211a perpendicular to its own axial direction Z. The area of ​​the pressure relief part 71 can be the area of ​​the smallest cross-section of the pressure relief part 71 perpendicular to its own thickness direction.

[0295] Compared to the electrode lead-out hole 211a, the pressure relief section 71 can have a larger area, which allows for rapid release of internal temperature and pressure in the cylindrical battery cell 7 during thermal runaway. Compared to the pressure relief section 71, the electrode lead-out hole 211a can have a smaller area, which reduces the impact of the electrode lead-out hole 211a on the strength of the wall portion 20a, reduces deformation of the portion of the wall portion 20a near the electrode lead-out hole 211a, and lowers the risk of the electrode terminal 30 detaching from the wall portion 20a.

[0296] In some embodiments, the pressure relief part 71 is circular, and the diameter φ1 of the pressure relief part 71 satisfies: 20mm≤φ1≤35mm. Optionally, 22mm≤φ1≤32mm.

[0297] In some embodiments, electrode terminals 30 are disposed on end wall 211, and pressure relief mechanism 70 is disposed on end cap 22.

[0298] In some embodiments, the pressure relief mechanism 70 is integrally formed with the end cap 22. Exemplarily, the end cap 22 has an end cap recess 221, and the weak portion 72 includes the bottom wall of the end cap recess 221. The end cap recess 221 is disposed around the pressure relief portion 71.

[0299] In some embodiments, the housing 20 includes a housing 21 and an end cap 22. The housing 21 includes a side wall 212 and an end wall 211 connected to each other. The side wall 212 surrounds the electrode assembly 10. The end wall 211 and the end cap 22 are opposite each other along the axial direction Z of the cylindrical battery cell 7. The end cap 22 is connected to the side wall 212. The end wall 211 is a wall portion 20a.

[0300] The end of the housing 21 away from the end wall 211 has an opening, and the end cap 22 covers the opening of the housing 21.

[0301] In some examples, the sidewall 212 and the endwall 211 may be integrally formed. In other examples, the sidewall 212 and the endwall 211 may also be formed independently and joined together by bonding, snap-fitting, welding or other means.

[0302] In some embodiments, the end wall 211 and the side wall 212 are integrally formed, and the connection strength between the end wall 211 and the side wall 212 is high. In the event of thermal runaway of the cylindrical battery cell 7, the side wall 212 can bind the end wall 211, reduce the deformation of the end wall 211, reduce the risk of the electrode terminal 30 detaching from the end wall 211, and improve the reliability of the cylindrical battery cell 7.

[0303] In some embodiments, the sidewall 212 is made of steel.

[0304] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1 mm.

[0305] As an example, the thickness of the sidewall 212 is 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.35mm, 0.38mm, 0.40mm, 0.42mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, or 1mm.

[0306] As an example, the material of sidewall 212 includes stainless steel.

[0307] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 0.9 mm, optionally 0.3 mm to 0.6 mm.

[0308] In some embodiments, the end wall 211 is made of the same material as the side wall 212.

[0309] In some embodiments, the end cap 22 is made of steel.

[0310] In some embodiments, the electrode assembly 10 further includes a second tab 10c, which has the opposite polarity to the first tab 10b. The second tab 10c is electrically connected to the end wall 211.

[0311] In some examples, a first tab 10b is disposed at the end of the electrode assembly 10 facing the wall portion 20a, and a second tab 10c is disposed at the end of the electrode assembly 10 facing the end cap 22. The first tab 10b and the second tab 10c are respectively disposed at opposite ends of the electrode assembly 10, which can reduce the risk of the first tab 10b and the second tab 10c coming into contact.

[0312] In other examples, both the first tab 10b and the second tab 10c are disposed at the end of the electrode assembly 10 facing the wall portion 20a. The second tab 10c can be directly connected to the wall portion 20a, or it can be indirectly connected to the wall portion 20a through other conductive structures.

[0313] The wall portion 20a and the electrode terminal 30 can serve as two electrodes of the cylindrical battery cell 7 and are located on the same side of the cylindrical battery cell 7. When multiple cylindrical battery cells 7 are assembled into a group, it is convenient to connect the current collector to the wall portion 20a or the current collector to the electrode terminal 30, thus simplifying the structure of the battery device.

[0314] In some embodiments, the first tab 10b is located at one end of the electrode assembly 10 facing the end wall 211, and the second tab 10c is located at one end of the electrode assembly 10 facing the end cap 22. The cylindrical battery cell 7 also includes a second current collector 80 connected to the second tab 10c; the second current collector 80 is connected to at least one of the end cap 22 and the side wall 212.

[0315] In some examples, the second current collector 80 is connected to the end cap 22, which is electrically connected to the side wall 212. The second tab 10c is electrically connected to the wall portion 20a via the second current collector 80, the end cap 22, and the side wall 212.

[0316] In other examples, the second current collector 80 is connected to the sidewall 212. The second tab 10c is electrically connected to the wall portion 20a via the second current collector 80 and the sidewall 212. Optionally, the wall portion 20a is insulated from the sidewall 212.

[0317] Before the cylindrical battery cell 7 experiences thermal runaway and the pressure relief mechanism 70 is activated, the side wall 212 or end cap 22 can bind the electrode terminal 30 through the second current collector 80, the electrode assembly 10 and the first current collector 40, thereby reducing the deformation of the wall portion 20a during the process of increasing internal pressure in the cylindrical battery cell 7 and reducing the risk of the electrode terminal 30 detaching from the wall portion 20a.

[0318] In some embodiments, the second current collector 80 is connected to the end cap 22. Optionally, the second current collector 80 is welded to the end cap 22.

[0319] In some embodiments, the end cap 22 is welded to the side wall 212.

[0320] In some embodiments, the height of the housing 20 is 50 mm to 150 mm.

[0321] For example, the height of the outer casing 20 is 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm, 140mm, 145mm or 150mm.

[0322] Optionally, the height of the housing 20 is 60mm-100mm.

[0323] In some embodiments, the height of the housing 20 is 1.3 to 4 times the diameter of the housing 20. Exemplarily, the height of the housing 20 may be the dimension of the housing 20 along the axial direction Z of the cylindrical battery cell 7. When the housing 20 meets the above dimensional requirements, the structural stability of the housing 20 is higher, which can improve the reliability of the cylindrical battery cell 7.

[0324] In some embodiments, the diameter of the cylindrical battery cell 7 is 35 mm to 80 mm. For example, the diameter of the cylindrical battery cell 7 may be 35 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm or 80 mm.

[0325] Setting the diameter of the cylindrical battery cell 7 to be greater than or equal to 35 mm can improve the capacity and energy density of the cylindrical battery cell 7. The diameter of the cylindrical battery cell 7 is related to the gas generation during thermal runaway of the cylindrical battery cell 7. Setting the diameter of the cylindrical battery cell 7 to be less than or equal to 80 mm can limit the maximum gas pressure of the cylindrical battery cell 7 during thermal runaway and reduce the risk of the electrode terminal 30 detaching from the wall 20a.

[0326] Optionally, the diameter of the cylindrical battery cell 7 is 45 mm to 60 mm.

[0327] Figure 14 This is a partial cross-sectional schematic diagram of a cylindrical battery cell provided for other embodiments of this application.

[0328] Reference Figure 14 In some embodiments, the cylindrical battery cell 7 further includes a cover plate 90, at least a portion of which is received in a recess 311 and connected to the terminal body 31.

[0329] The cover plate 90 can be installed onto the terminal body 31 after the connecting part 312 and the first current collector 40 are welded together. In the event of thermal runaway of the cylindrical battery cell 7, the cover plate 90 can constrain the terminal body 31, reduce the deformation of the terminal body 31, reduce the stress at the connection between the first limiting part 32 and the terminal body 31, reduce the risk of cracking at the connection between the first limiting part 32 and the terminal body 31, and reduce the possibility of the electrode terminal 30 detaching from the wall part 20a. This is beneficial for achieving directional pressure relief of the cylindrical battery cell 7 and improving the reliability of the cylindrical battery cell 7.

[0330] Additionally, the connecting portion 312 is welded to the first current collector 40 to form a welded portion P. The cover plate 90 can also cover the welded portion P to seal any weld slag remaining on the welded portion P within the recess 311.

[0331] In some embodiments, the cover plate 90 is entirely received in the recess 311.

[0332] In some embodiments, the outer periphery of the cover plate 90 is welded to the terminal body 31.

[0333] In some embodiments, in the axial direction Z, the outer surface of the cover plate 90 is closer to the connection portion 312 than the outer surface of the terminal body 31.

[0334] Figure 15 This is a partial cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of this application.

[0335] Reference Figure 15 In some embodiments, the sidewall 212 is provided with an inwardly protruding protrusion 2121, and the second current collector 80 is connected to the protrusion 2121.

[0336] For example, the protrusion 2121 can be a solid structure or a hollow structure.

[0337] As an example, the second current collector 80 may be welded to the protrusion 2121; alternatively, the second current collector 80 may also be press-fitted to the protrusion 2121.

[0338] For example, the second current collector 80 is connected to the side of the protrusion 2121 facing the second electrode 10c, or it can be connected to the side of the protrusion 2121 facing the end cap 22.

[0339] Connecting the second current collector 80 to the protrusion 2121 can shorten the conductive path between the second tab 10c and the wall 20a, reduce resistance, reduce heat generation, and improve the cycle performance of the cylindrical battery cell 7.

[0340] In some embodiments, at least a portion of the protrusion 2121 is located between the end cap 22 and the second tab 10c in the axial direction Z. The protrusion 2121 overlaps with the second tab 10c in the axial direction Z, which can limit the movement of the second tab 10c in the axial direction Z when the cylindrical battery cell 7 is subjected to external impact, thereby reducing the risk of failure of the connection between the second tab 10c and the second current collector 80.

[0341] In some embodiments, a portion of the second current collector 80 is located on the side of the protrusion 2121 facing the end cap 22 and is connected to the protrusion 2121. The second current collector 80 is connected to the protrusion 2121 from the outside of the protrusion 2121, which can reduce assembly difficulty.

[0342] In some embodiments, the second current collector 80 is welded to the protrusion 2121.

[0343] In some embodiments, the sidewall 212 has a sidewall recess 2122 on its outer side, which corresponds to the position of the protrusion 2121. As an example, after the electrode assembly 10 is installed into the housing 21, the sidewall 212 is pressed from the outside to form an inwardly protruding protrusion 2121.

[0344] In some embodiments, the sidewall 212 further includes a crimping portion 2123, which extends from the end of the protrusion 2121 away from the wall portion 20a and surrounds the end cap 22.

[0345] A portion of the crimping part 2123 is bent to form a flange structure, and a portion of the end cap 22 is located between the flange structure and the protrusion 2121 in the axial direction Z. The protrusion 2121 and the flange structure can limit the end cap 22 to fix the end cap 22 in the axial direction Z.

[0346] In some embodiments, the cylindrical battery cell includes a second insulating member 91 that insulates and isolates the end cap 22 from the sidewall 212.

[0347] This application also provides a battery device including a plurality of cylindrical battery cells 7 according to any of the above embodiments.

[0348] According to some embodiments of this application, this application also provides an electrical device, including a cylindrical battery cell 7 or a battery device according to any of the above embodiments, wherein the cylindrical battery cell 7 is used to provide electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems that utilize the cylindrical battery cell 7.

[0349] Reference Figures 4 to 12 This application provides a cylindrical battery cell 7, which includes a housing 20, an electrode assembly 10, a first current collector 40, a second current collector 80, an electrode terminal 30, and a pressure relief mechanism 70.

[0350] The outer casing 20 includes a wall portion 20a, and the wall portion 20a is provided with an electrode lead-out hole 211a. Specifically, the outer casing 20 includes a housing 21 and an end cap 22. The housing 21 includes an end wall 211 and a side wall 212. The end wall 211 is disposed opposite to the end cap 22, and the side wall 212 surrounds the end wall 211 and connects the end wall 211 and the end cap 22. The end wall 211 and the side wall 212 are integrally formed. The end wall 211 is the wall portion 20a.

[0351] The electrode assembly 10 is housed within the housing 20, and the electrode assembly 10 and the wall portion 20a are arranged along the axial direction Z of the cylindrical battery cell 7. The electrode assembly 10 includes a first tab 10b and a second tab 10c with opposite polarities. The first tab 10b is disposed at the end of the electrode assembly 10 facing the wall portion 20a, and the second tab 10c is disposed at the end of the electrode assembly 10 facing the end cap 22.

[0352] Electrode terminals 30 are disposed on the wall portion 20a.

[0353] The electrode terminal 30 includes a terminal body 31, a first limiting portion 32, and a second limiting portion 33. A portion of the terminal body 31 is accommodated in an electrode lead-out hole 211a. The first limiting portion 32 is disposed around the terminal body 31, and the second limiting portion 33 is disposed around the terminal body 31. At least a portion of the first limiting portion 32 is located along the axial direction Z on the side of the wall portion 20a facing the electrode assembly 10, and at least a portion of the second limiting portion 33 is located along the axial direction Z on the side of the wall portion 20a facing away from the electrode assembly 10. Along the axial direction Z, a portion of the wall portion 20a is located between the first limiting portion 32 and the second limiting portion 33.

[0354] The terminal body 31 has a recess 311 along the axial direction Z away from the electrode assembly 10, and the terminal body 31 includes a connecting portion 312 corresponding to the bottom surface 311a of the recess 311. In the axial direction Z, the first current collector 40 is located on the side of the first tab 10b near the wall portion 20a; the connecting portion 312 is located on the side of the first current collector 40 away from the first tab 10b, and is welded to the first current collector 40.

[0355] Along the Z-axis, the second current collector 80 is located on the side of the second tab 10c near the end cap 22; the second current collector 80 is welded to the end cap 22 and the second tab 10c. The end cap 22 is welded to the side wall 212. The second tab 10c is electrically connected to the wall portion 20a through the second current collector 80, the end cap 22, and the side wall 212.

[0356] The dimension of the first limiting part 32 along the axial direction Z is larger than the dimension of the connecting part 312 along the axial direction Z, and the dimension of the first limiting part 32 along the axial direction Z is larger than the dimension of the second limiting part 33 along the axial direction Z. In the radial direction of the cylindrical battery cell 7, the dimension of the first limiting part 32 protruding from the outer peripheral surface 313 of the terminal body 31 is larger than the dimension of the second limiting part 33 protruding from the outer peripheral surface 313 of the terminal body 31.

[0357] Example

[0358] The following embodiments describe the contents disclosed in this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosures in this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0359] Example 1

[0360] 1. Preparation of positive electrode sheet

[0361] The positive electrode sheet includes a positive current collector and a positive electrode film layer. The positive electrode film layer is located on both sides of the positive current collector. The positive current collector is an aluminum foil. The positive electrode film layer is formed by uniformly coating the surface of the positive current collector aluminum foil with a positive electrode slurry (solvent is N-methylpyrrolidone NMP), and then drying and cold pressing it. The positive electrode film layer includes positive active material, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) in a weight ratio of 96.5:2:1.5.

[0362] Positive electrode active materials include those with the molecular formula LiNi 0.9 Co 0.05 Mn 0.05 Compounds of O2 (Ni90).

[0363] 2. Preparation of negative electrode sheet

[0364] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer. The negative electrode film layer is located on both sides of the negative electrode current collector. The negative electrode current collector is a copper foil. The negative electrode film layer is formed by uniformly coating the surface of the copper foil of the negative electrode current collector with a negative electrode slurry (the solvent is deionized water), and then drying and cold pressing it. The negative electrode film layer includes a negative electrode active material, a binder styrene-butadiene rubber (SBR), a thickener sodium carboxymethyl cellulose (CMC-Na), and a conductive agent acetylene black in a weight ratio of 96.2:1.8:1.2:0.8.

[0365] The negative electrode active materials include artificial graphite and silicon-based materials (specifically silicon carbide compounds), and the silicon content in the negative electrode film is 5%.

[0366] 3. Isolation components

[0367] The separator is a polypropylene (PP) film layer.

[0368] 4. Preparation of electrolyte

[0369] The electrolyte comprises an organic solvent and a lithium salt. The organic solvent includes chain ester solvents and cyclic ester solvents (ethylene carbonate). The chain ester solvents include chain carbonates (dimethyl carbonate, DMC) and chain carboxylic acid esters (methyl acetate and ethyl acetate in a 1:1 mass ratio), with a mass ratio of chain carbonate, chain carboxylic acid ester, and ethylene carbonate of 3:4:3. The lithium salt includes lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI). Dimethyl carbonate (DMC), methyl acetate, ethyl acetate, and ethylene carbonate are mixed according to the above mass ratio. Then, thoroughly dried lithium salts are dissolved in the mixed organic solvent to prepare the electrolyte. The molar concentration of lithium hexafluorophosphate (LiPF6) is 0.6 mol / L, and the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is 0.4 mol / L.

[0370] 5. Preparation of cylindrical battery cells

[0371] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The positive electrode, separator, and negative electrode are then wound to form an electrode assembly. This assembly is placed in a cylindrical casing, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a cylindrical battery cell is obtained. The cylindrical battery cell has a diameter of 46 mm and a height of 95 mm.

[0372] The outer casing includes a housing and an end cap. The housing includes an integrally formed sidewall and an end wall, with the sidewall surrounding the electrode assembly. The end cap and end wall are axially opposite each other along the cylindrical battery cell. The end cap is equipped with a pressure relief mechanism. The cylindrical battery cell includes an electrode terminal located on the end wall. The electrode terminal includes a terminal body, a first limiting portion, and a second limiting portion. The diameter of the first limiting portion is 32 mm, and the diameter of the terminal body is 16 mm. The terminal body has a recess and a connecting portion, with the connecting portion having a diameter of 8 mm. The axial dimension T1 of the first limiting portion is 1.1 mm, and the axial dimension T2 of the connecting portion of the terminal body is 1 mm.

[0373] Examples 2-9:

[0374] Cylindrical battery cells were prepared using a method similar to that of Example 1. The difference from Example 1 is that T1 and / or T2 were adjusted, as detailed in Table 1.

[0375] Comparative Example 1:

[0376] Cylindrical battery cells were prepared using a method similar to that in Example 1. The difference from Example 1 is that T1 and T2 were adjusted, as detailed in Table 1.

[0377] Performance testing

[0378] 1. Volumetric energy density.

[0379] At 25°C, the cylindrical battery cells prepared in the examples or comparative examples were charged at a constant current of 1C until the voltage of the cylindrical battery cell reached 4.25V. The cells were then charged at a constant voltage until the current reached 0.05C. After the cylindrical battery cells were allowed to stand for 30 minutes, they were discharged at a constant current of 1C until the voltage of the battery cell reached 2.5V. The discharge capacity at this point was recorded. The discharge capacity of the cylindrical battery cell divided by the volume of the cylindrical battery cell is the energy density of the cylindrical battery cell. The volume of the cylindrical battery cell is V = π × 23mm × 23mm × 95mm = 158008.42mm². 3 ≈0.158L.

[0380] 2. Thermal runaway test

[0381] At 25°C, the cylindrical battery cells prepared in the examples or comparative examples were continuously charged at a constant current of 1C until thermal runaway occurred. Observe whether the electrode terminals detached from the casing.

[0382] Test Results

[0383] The test results are shown in Table 1.

[0384] Table 1

[0385]

[0386] Referring to Examples 1-9 and Comparative Example 1, in this embodiment, the axial dimension of the first limiting portion is set to be larger than that of the connecting portion. This improves the structural strength of the first limiting portion, reduces bending deformation, reduces the possibility of cracking at the connection between the first limiting portion and the terminal body, lowers the risk of the electrode terminal detaching from the wall, facilitates directional pressure relief of the cylindrical battery cell, and improves the reliability of the cylindrical battery cell. Setting the axial dimension of the first limiting portion to 1.1mm-1.8mm and the axial dimension of the connecting portion to 0.5mm-1.0mm can, to a certain extent, balance the reliability and volumetric energy density of the cylindrical battery cell.

[0387] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0388] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A cylindrical battery cell, characterized in that, include: The outer casing includes a wall portion, wherein the wall portion is provided with electrode lead-out holes; An electrode assembly is housed within the housing, the electrode assembly and the wall portion being arranged along the axial direction of the cylindrical battery cell, the electrode assembly including a first tab; The first current collector is housed within the housing and electrically connected to the first electrode tab; An electrode terminal is disposed on the wall portion. The electrode terminal includes a terminal body and a first limiting portion. At least a portion of the terminal body is accommodated in the electrode lead-out hole. The terminal body has a recess on at least one side along the axial direction. The terminal body includes a connecting portion corresponding to the bottom surface of the recess. The connecting portion is welded to the first current collector. The first limiting portion is connected to the terminal body and protrudes from the outer peripheral surface of the terminal body. At least a portion of the first limiting portion is located along the axial direction on the side of the wall portion facing the electrode assembly, and the dimension of the first limiting portion along the axial direction is larger than the dimension of the connecting portion along the axial direction.

2. The cylindrical battery cell according to claim 1, characterized in that, The ratio of the dimension of the first limiting part along the axial direction to the dimension of the connecting part along the axial direction is 1.1-3.

6.

3. The cylindrical battery cell according to claim 1, characterized in that, The dimension of the connecting part along the axial direction is 0.5mm-1.0mm, and the dimension of the first limiting part along the axial direction is 1.1mm-1.8mm.

4. The cylindrical battery cell according to claim 1, characterized in that, The electrode terminal further includes a second limiting part, which is connected to the terminal body and protrudes from the outer peripheral surface of the terminal body; Along the axial direction, a portion of the wall portion is located between the first limiting portion and the second limiting portion, wherein the size of the first limiting portion is larger than the size of the second limiting portion.

5. The cylindrical battery cell according to claim 4, characterized in that, In the radial direction of the cylindrical battery cell, the first limiting portion protrudes beyond the outer peripheral surface by a larger dimension than the second limiting portion protrudes beyond the outer peripheral surface.

6. The cylindrical battery cell according to claim 5, characterized in that, The ratio of the size of the first limiting part protruding from the outer peripheral surface to the size of the second limiting part protruding from the outer peripheral surface is greater than or equal to 2.

7. The cylindrical battery cell according to claim 4, characterized in that, It also includes a first insulating element and a protective element, both of which surround the terminal body; In the axial direction, at least a portion of the first insulating member is located between the protective member and the wall portion, and at least a portion of the protective member is located between the first insulating member and the second limiting portion; The tensile strength of the protective component is greater than that of the first insulating component.

8. The cylindrical battery cell according to claim 1, characterized in that, The electrode terminal further includes a transition portion, which surrounds the terminal body and is connected to the outer peripheral surface; The transition portion is located on one side of the first limiting portion along the axial direction and is connected to the first limiting portion; In the radial direction of the cylindrical battery cell, the first limiting portion protrudes outward from the transition portion.

9. The cylindrical battery cell according to claim 8, characterized in that, Along the direction away from the terminal body, the dimension of the transition portion gradually decreases along the axial direction.

10. The cylindrical battery cell according to claim 9, characterized in that, The maximum dimension of the transition portion along the axial direction is 0.1mm-0.8mm; and / or Along the radial direction of the cylindrical battery cell, the size of the transition portion is 0.1mm-0.8mm.

11. The cylindrical battery cell according to claim 8, characterized in that, In the axial direction, the transition portion is located on the side of the first limiting portion opposite to the electrode assembly; In the same plane perpendicular to the axis, the orthographic projection of the transition portion lies within the orthographic projection of the electrode lead-out hole.

12. The cylindrical battery cell according to claim 1, characterized in that, The first limiting portion includes an overlapping portion, and in the same plane perpendicular to the axis, the orthographic projection of the overlapping portion is located within the projection of the wall portion; The connecting part is circular, and the overlapping part is annular, with the ring width of the overlapping part being greater than or equal to the radius of the connecting part.

13. The cylindrical battery cell according to claim 1, characterized in that, The housing includes a sidewall that surrounds the electrode assembly, and the wall portion is connected to the sidewall; At least a portion of the wall has a thickness greater than the thickness of the sidewall.

14. The cylindrical battery cell according to claim 1, characterized in that, The thickness of the wall portion is 0.4mm-1.2mm.

15. The cylindrical battery cell according to claim 1, characterized in that, The tensile strength of the first limiting part is 125MPa-190MPa.

16. The cylindrical battery cell according to claim 1, characterized in that, The diameter of the cylindrical battery cell is D; The diameter of the first limiting part is D1, 0.65≤D1 / D≤0.80; and / or, the diameter of the terminal body is D2, 0.30≤D2 / D≤0.50; and / or, the diameter of the connecting part is D3, 0.10≤D3 / D≤0.

25.

17. The cylindrical battery cell according to claim 1, characterized in that, The recess is located on the side of the terminal body facing away from the electrode assembly.

18. The cylindrical battery cell according to claim 17, characterized in that, It also includes a cover plate, at least a portion of which is received in the recess and connected to the terminal body.

19. The cylindrical battery cell according to claim 17, characterized in that, An opening is formed on the side of the recess away from the connecting portion; The ratio of the diameter of the opening to the diameter of the terminal body is 0.3-0.

6.

20. The cylindrical battery cell according to claim 1, characterized in that, The electrode terminals are integrally formed.

21. The cylindrical battery cell according to claim 1, characterized in that, It also includes a pressure relief mechanism disposed on the housing, the pressure relief mechanism being disposed on the side of the electrode assembly away from the electrode terminals; The pressure relief mechanism includes a pressure relief section and a weak section provided along the outer periphery of the pressure relief section, wherein the area of ​​the pressure relief section is larger than the area of ​​the electrode lead-out hole.

22. The cylindrical battery cell according to claim 1, characterized in that, The housing includes a shell and an end cap. The shell includes sidewalls and an end wall that are connected to each other. The sidewalls surround the electrode assembly. The end wall and the end cap are opposite each other along the axial direction of the cylindrical battery cell. The end cap is connected to the sidewalls. The end wall is the wall portion.

23. The cylindrical battery cell according to claim 22, characterized in that, The electrode assembly further includes a second electrode tab, which has the opposite polarity to the first electrode tab. The second electrode is electrically connected to the end wall.

24. The cylindrical battery cell according to claim 23, characterized in that, The first tab is located at the end of the electrode assembly facing the end wall, and the second tab is located at the end of the electrode assembly facing the end cap; The cylindrical battery cell further includes a second current collector connected to the second tab; the second current collector is connected to at least one of the end cap and the side wall.

25. The cylindrical battery cell according to claim 24, characterized in that, The sidewall is provided with an inwardly protruding part, and the second current collecting member is connected to the protruding part.

26. The cylindrical battery cell according to claim 25, characterized in that, A portion of the second current collector is located on the side of the protrusion facing the end cap and is connected to the protrusion.

27. The cylindrical battery cell according to any one of claims 1-26, characterized in that, The height of the outer casing is 50mm to 150mm; and / or The diameter of the cylindrical battery cell is 35mm to 80mm.

28. A battery device, characterized in that, It includes multiple cylindrical battery cells according to any one of claims 1-27.

29. An electrical appliance, characterized in that, Includes the battery device according to claim 28, the battery device being used to provide electrical energy.

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