Cylindrical battery cell, battery apparatus, and electrical device

Abstract

The present application provides a cylindrical battery cell, a battery apparatus, and an electrical device. The cylindrical battery cell comprises a casing, an electrode assembly, and current collecting members. The casing is provided with a pressure relief portion. The electrode assembly comprises two electrode sheets having opposite polarities. Each electrode sheet comprises an electrode sheet body and a tab that are arranged in an axial direction, wherein at least a portion of the electrode sheet body is coated with an active material layer, and the tab is not coated with an active material layer. The current collecting members are arranged in the casing. Each tab comprises a first tab winding portion and a second tab winding portion located on the periphery of the first tab winding portion, each current collecting member is welded to the corresponding second tab winding portion to form a first welding portion, and each current collecting member is not welded to the corresponding first tab winding portion. Each electrode sheet comprises a first electrode sheet winding portion, and each first tab winding portion is formed as a portion of the corresponding first electrode sheet winding portion. On a projection plane perpendicular to the axial direction, the orthographic projections of the first electrode sheet winding portions at least partially overlap the orthographic projection of the pressure relief portion.

Description

Cylindrical battery cells, battery devices and electrical equipment 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. Summary of the Invention

[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 casing, an electrode assembly, and a current collector. The casing has a pressure relief portion at at least one end along the axial direction of the cylindrical battery cell. At least a portion of the electrode assembly is disposed within the casing. The electrode assembly has a wound structure and includes two electrodes with opposite polarities. At least one electrode includes an electrode body and a tab arranged axially; at least a portion of the electrode body is coated with an active material layer, and at least a portion of the tab is not coated with an active material layer. At least a portion of the current collector is disposed within the casing. The tab includes a first tab winding portion and a second tab winding portion located outside the first tab winding portion; the current collector is welded to the second tab winding portion to form a first weld portion, and the current collector is not welded to the first tab winding portion. The electrode includes a first electrode winding portion, and a first electrode ear winding portion is formed on a part of the first electrode winding portion. On a projection plane perpendicular to the axial direction, the orthographic projection of the first electrode winding portion at least partially overlaps with the orthographic projection of the pressure relief portion. The pressure relief portion is configured to at least partially open and form an exhaust passage when pressure is released, and at least a portion of the first electrode winding portion is released to the outside of the housing through the exhaust passage.

[0006] In this embodiment, when a cylindrical battery cell experiences thermal runaway due to an unexpected event such as a short circuit, the pressure inside the casing increases, the pressure relief section opens, and an exhaust channel is formed, allowing the high-temperature gas inside the casing to be discharged through the exhaust channel. The current collector is not welded to the first electrode lug winding portion, thereby reducing the binding effect of the current collector on the first electrode lug winding portion, i.e., reducing the binding effect of the current collector on the first electrode winding portion. During the thermal runaway of the cylindrical battery cell, at least a portion of the first electrode winding portion can be released to the outside of the casing through the exhaust channel under the action of gas pressure. On one hand, as at least a portion of the first electrode winding portion is ejected through the exhaust channel, electrode fragments, high-temperature gas, electrolyte, and other substances can also be ejected along with the first electrode winding portion, thereby rapidly relieving pressure. On the other hand, the first electrode winding portion is located in the middle of the electrode assembly. After at least a portion of the first electrode winding portion is discharged through the exhaust channel, a channel opposite to the exhaust channel is formed in the middle of the electrode assembly, which is beneficial for the discharge of high-temperature gas. After at least a portion of the first electrode winding is discharged through the venting channel, the electrode remaining inside the casing becomes more porous, facilitating gas flow between the electrodes. In summary, the embodiments of this application can help increase the venting rate, reduce the risk of cylindrical battery cell explosion, and improve the reliability of cylindrical battery cells during thermal runaway.

[0007] In some embodiments, the first electrode lug winding portion includes a first loop portion. In the axial direction, the second electrode lug winding portion extends beyond the first loop portion in a direction away from the electrode body.

[0008] By reducing the axial dimension of the first coil, the mutual binding effect between the first and second tab winding portions can be weakened. During thermal runaway of a cylindrical battery cell, the mutual binding effect between the first and second tab winding portions is easily broken under air pressure. This allows the portion of the first electrode winding corresponding to the first coil to be easily discharged through the exhaust channel under air pressure, increasing the exhaust rate, reducing the risk of cylindrical battery cell explosion, and improving the reliability of the cylindrical battery cell.

[0009] In some embodiments, the first electrode loop winding portion includes a second loop portion located outside the first loop portion, the second loop portion being connected to the second electrode loop winding portion and the first loop portion; axially, the second loop portion extends beyond the first loop portion in a direction away from the electrode body.

[0010] By reducing the axial dimension of the first coil, the mutual binding effect between the first and second coils can be weakened. During thermal runaway of a cylindrical battery cell, this binding effect is easily broken under pressure, allowing the portion of the first electrode winding corresponding to the first coil to be easily discharged through the exhaust channel under pressure. This increases the exhaust rate, reduces the risk of explosion of the cylindrical battery cell, and improves its reliability. The second coil extends axially beyond the first coil, supporting the current collector. This improves the stability of the current collector, reduces the risk of incomplete soldering, and increases weld strength during welding of the current collector and the second electrode winding.

[0011] In some embodiments, the cylindrical battery cell includes electrode terminals disposed on the housing, which are welded to a current collector to form a second weld portion. On a projection plane perpendicular to the axial direction, the orthographic projection of the second weld portion is located outside the orthographic projection of the first ring portion.

[0012] The second electrode lug extends axially beyond the first coil, supporting the current collector. Positioning the second weld portion outside the first coil effectively supports the welded area of ​​the current collector during the welding process between the current collector and the electrode terminals, reducing the risk of incomplete welds and increasing weld strength.

[0013] In some embodiments, the tab includes a plurality of segments distributed along the winding direction of the electrode assembly, with a cut-off groove provided between any two adjacent segments along the winding direction. At least a portion of the plurality of segments is formed in a part of the second coil. In a projection plane perpendicular to the axial direction, the orthographic projection of the bottom surface of at least one cut-off groove lies within the orthographic projection of the pressure relief portion.

[0014] By incorporating a cut-off groove in the second coil, the mutual binding effect between adjacent segments in the winding direction of the second coil is weakened. In the event of thermal runaway in a cylindrical battery cell, the second coil can disperse under pressure, allowing the portion of the first electrode winding corresponding to the second coil to be discharged through the exhaust channel under pressure. This further increases the exhaust rate, reduces the risk of cylindrical battery cell explosion, and improves the reliability of the cylindrical battery cell.

[0015] In some embodiments, the cylindrical battery cell includes electrode terminals disposed on the housing, which are welded to a current collector to form a second welded portion. On a projection plane perpendicular to the axial direction, the two ends of the orthographic projection of the second welded portion have a first projection endpoint and a second projection endpoint, respectively. The first projection endpoint is closer to the central axis of the cylindrical battery cell than the second projection endpoint. The region between a first arc line passing through the first projection endpoint and surrounding the first loop portion and a second arc line passing through the second projection endpoint and surrounding the first loop portion is a first transverse region. At least some cut-off grooves form a first group of cut-off grooves, in which the orthographic projection of the bottom surface of all cut-off grooves lies within the first transverse region. In the first group of cut-off grooves, the number of turns of a single cut-off groove is ≤3; and / or, in the first group of cut-off grooves, the number of cut-off grooves that are radially opposite and interconnected along the electrode assembly is ≤3. This application embodiment reduces the impact of the cut-off groove on the strength of the portion of the electrode corresponding to the first transverse region, reduces the risk of collapse of the portion of the electrode corresponding to the first transverse region, thereby enabling the electrode to stably support the area where the current collector needs to be welded to the electrode terminal, reduces the risk of incomplete welding, and improves welding strength.

[0016] In some embodiments, the tab includes a plurality of segments distributed along the winding direction of the electrode assembly, with a cutting groove provided between any two adjacent segments along the winding direction. At least a portion of the plurality of segments is formed in a part of the second tab winding portion. A current collector is welded to a segment of the second tab winding portion to form a first weld portion. In a projection plane perpendicular to the axial direction, the orthographic projection of the bottom surface of at least one cutting groove lies within the orthographic projection of the pressure relief portion.

[0017] By providing a cutting groove in the second electrode winding section, the mutual binding effect between adjacent segments of the second electrode winding section in the winding direction is weakened. A portion of the electrode corresponding to the second electrode winding section (e.g., fragments, particles, etc. generated by the reaction of the electrode under high temperature and high pressure) can also be discharged outside the casing through the cutting groove and exhaust channel under the action of gas pressure, thereby increasing the exhaust rate, reducing the risk of cylindrical battery cell explosion, and improving the reliability of cylindrical battery cells.

[0018] In some embodiments, on a projection plane perpendicular to the axial direction, the two ends of the orthographic projection of the first weld portion have a third projection endpoint and a fourth projection endpoint, respectively. The third projection endpoint is closer to the central axis of the cylindrical battery cell than the fourth projection endpoint. The area between the third arc line passing through the third projection endpoint and surrounding the first electrode lug winding portion and the fourth arc line passing through the fourth projection endpoint and surrounding the first electrode lug winding portion is a second transverse region. At least some of the cut-off grooves form a second set of cut-off grooves. In the second set of cut-off grooves, the orthographic projection of the bottom surface of all cut-off grooves is located within the second transverse region. In the second set of cut-off grooves, the number of turns of a single cut-off groove is ≤3; and / or, in the second set of cut-off grooves, the number of cut-off grooves that are radially opposite and connected along the electrode assembly is ≤3. The embodiments of this application can reduce the impact of opening cut-off grooves on the number of layers of electrode lugs overlapping in the axial direction, reduce the risk of electrode lugs being welded through, and improve welding strength.

[0019] In some embodiments, among the multiple segments of the second tab winding portion, the segment furthest from the first tab winding portion is wound at least one turn along the winding direction. The segment furthest from the first tab winding portion is continuously arranged and wound at least one turn, which can bind the other segments from the outer periphery, thereby reducing the risk of the tab bulging outwards and deforming radially in the electrode assembly when the tab is under pressure, and improving the reliability of the cylindrical battery cell.

[0020] In some embodiments, at least one electrode includes a positive electrode, which includes an electrode body, a tab, and an insulating layer. The tab of the positive electrode is not coated with an active material layer. Axially, at least a portion of the insulating layer is disposed on the end region of the tab near the electrode body, and the cut-off piece is located on the side of the insulating layer away from the electrode body. By providing an insulating layer, the embodiments of this application can reduce the risk of burrs on the negative electrode contacting the tab and causing a short circuit, thereby improving reliability. By placing the cut-off piece on the side of the insulating layer away from the electrode body, the embodiments of this application reduce the stress transmitted to the insulating layer during the bending process of the cut-off piece, thus reducing the risk of the insulating layer falling off.

[0021] In some embodiments, at least one tab has a bent section at one end in the axial direction. The bent section includes at least one first bent portion bent relative to the electrode body in a direction close to the central axis of the cylindrical battery cell; and / or, the bent section includes at least one second bent portion bent relative to the electrode body in a direction away from the central axis of the cylindrical battery cell. By providing the bent section, the number of layers of the tab stacked in the axial direction can be increased, the density of the end region of the tab facing the current collector can be improved, the risk of poor soldering can be reduced, and the welding strength between the current collector and the tab can be improved.

[0022] In some embodiments, the bending section includes a first bending portion and a second bending portion, both of which are bent radially along the electrode assembly. The directional bending of the first and second bending portions helps to improve the density of the end region of the electrode tab facing the current collector.

[0023] In some embodiments, the bending segment includes a first bending portion and a second bending portion, which are alternately arranged along the axial direction. By increasing the number of bends in the bending segment, this application embodiment can increase the number of layers of the sheet stacked in the axial direction, improve the density of the end region of the electrode tab facing the current collector, reduce the risk of incomplete soldering, and improve the welding strength between the current collector and the electrode tab.

[0024] In some embodiments, each segment has a bent section at one end in the axial direction, which can form an overlapping area at the end of the tab away from the electrode body. In the overlapping area, the bent sections of at least two segments overlap in the axial direction. Welding the overlapping area to the current collector can reduce the risk of poor soldering and increase the welding area between the tab and the current collector, thereby improving the current carrying capacity.

[0025] In some embodiments, the tab further includes a transition connection portion, and the electrode body, the transition connection portion, and the segment are arranged sequentially along the axial direction; the transition connection portion and two segments adjacent to each other along the winding direction form a cutting groove, and the bottom surface of the cutting groove is formed on one side edge of the transition connection portion used to connect the segments. The transition connection portion can separate the electrode body from the segments, thereby reducing the force transmitted to the electrode body during the bending process of the segments, reducing the risk of deformation of the electrode body and the risk of active material falling off from the active material layer.

[0026] In some embodiments, the dimension of one edge of each segment used to connect the transition connection portion in the winding direction of the electrode assembly is L1, and the sum of the axial dimensions of the transition connection portion and the segment is L2, where 0.01 ≤ L2 / L1 ≤ 0.3. Limiting L2 / L1 to less than or equal to 0.3 can, to some extent, balance the space occupied by the tab in the axial direction and the current carrying capacity of the tab. Limiting L2 / L1 to greater than or equal to 0.01 reduces the difficulty of bending the segment.

[0027] In some embodiments, the axial dimension of the transition connection is L3, where 0.1mm ≤ L3 ≤ 2mm. Limiting L3 to less than or equal to 2mm saves axial space occupied by the transition connection, thereby increasing the energy density of the cylindrical battery cell. In this application embodiment, L3 is limited to greater than or equal to 0.1mm to reduce the force transmitted to the electrode body during bending, thus lowering the risk of electrode body deformation and the risk of active material shedding from the active material layer.

[0028] In some embodiments, the electrode tab is provided with a plurality of cut-off grooves, and the cut-off grooves and the cut pieces are arranged alternately along the winding direction of the electrode assembly.

[0029] By incorporating multiple segments and cutting grooves, directional bending of the segments is facilitated. Multiple cutting grooves reduce the binding effect between the segments. In the event of thermal runaway in a cylindrical battery cell, at least some of the segments can separate under pressure, allowing a portion of the electrode to be discharged through the exhaust channel, further increasing the exhaust rate, reducing the risk of explosion, and improving the reliability of the cylindrical battery cell.

[0030] In some embodiments, the axial dimension of the cut-off piece along the winding direction of the electrode assembly tends to decrease in the direction away from the electrode body, so as to reduce the difficulty of bending the cut-off piece.

[0031] In some embodiments, on a projection plane perpendicular to the axial direction, the orthographic projection of the first pole lug winding portion is located within the orthographic projection of the pressure relief portion.

[0032] The embodiments of this application can reduce the obstruction of the pressure relief section to the first electrode winding section when the cylindrical battery cell is thermally runaway, which is conducive to increasing the portion of the first electrode winding section discharged through the exhaust channel, improving the exhaust rate, reducing the risk of cylindrical battery cell explosion, and improving the reliability of cylindrical battery cell.

[0033] In some embodiments, the electrode sheet has a winding start end and a winding end end at its two ends along the winding direction of the electrode assembly. In the radial direction of the electrode assembly, the winding start end is closer to the central axis of the cylindrical battery cell than the winding end end. In a projection plane perpendicular to the axial direction, the orthographic projection of the winding start end lies within the orthographic projection of the pressure relief portion.

[0034] When a cylindrical battery cell experiences thermal runaway, the starting end of the winding can easily be discharged to the outside of the casing through the exhaust channel under the action of air pressure. This helps to reduce the resistance of the first electrode winding part being discharged through the exhaust channel, increase the exhaust rate, reduce the risk of cylindrical battery cell explosion, and improve the reliability of cylindrical battery cell.

[0035] In some embodiments, the electrode assembly has a central hole that extends axially. A first electrode lug is wound around the outer periphery of the central hole, and the orthographic projection of the central hole lies within the orthographic projection of the pressure relief portion in a projection plane perpendicular to the axial direction.

[0036] When thermal runaway occurs in a cylindrical battery cell, gas can act on the pressure relief section through the central hole, thereby opening the pressure relief section and forming an exhaust channel. The central hole reduces the risk of gas blockage and the inability of the pressure relief section to open in time. The central hole can both reduce the binding effect on the winding start end of the first electrode and guide gas flow, increasing the gas pressure on the first electrode winding section. This allows at least a portion of the first electrode winding section to be easily discharged through the exhaust channel under pressure, increasing the exhaust rate, reducing the risk of cylindrical battery cell explosion, and improving the reliability of the cylindrical battery cell.

[0037] In some embodiments, the outer diameter of the electrode assembly is D1, the diameter of the central hole is D2, and D2 / D1 ∈ [5%, 25%].

[0038] Setting D2 / D1 to 5% or greater increases the venting efficiency of the center hole, reduces the resistance encountered by the first electrode winding portion during ejection to the outside of the casing, improves the venting rate, reduces the risk of cylindrical battery cell explosion, and enhances the reliability of the cylindrical battery cell. Setting D2 / D1 to 25% or less reduces the impact of the center hole on the energy density of the cylindrical battery cell and reduces the risk of collapse in the middle of the electrode assembly.

[0039] In some embodiments, in a projection plane perpendicular to the axial direction, the orthographic projection of the second pole ear winding portion at least partially overlaps with the orthographic projection of the pressure relief portion.

[0040] When thermal runaway occurs in a cylindrical battery cell, a portion of the electrode corresponding to the second tab (e.g., fragments or particles generated by the reaction of the electrode under high temperature and high pressure) can also be discharged outside the casing through the exhaust channel under the action of gas pressure, thereby increasing the exhaust rate, reducing the risk of cylindrical battery cell explosion, and improving the reliability of cylindrical battery cell.

[0041] In some embodiments, in the winding direction of the electrode assembly, the length of the second electrode lug winding portion is greater than the length of the first electrode lug winding portion.

[0042] The second tab winding portion has a large length in the winding direction, which helps to increase the radial dimension of the second tab winding portion in the electrode assembly, that is, helps to increase the radial dimension of the first welding portion in the electrode assembly, thereby increasing the current flow area between the current collector and the tab, and improving the current flow capacity of the cylindrical battery cell.

[0043] In some embodiments, both electrodes include an electrode body and a tab, wherein the tab of one electrode is a first tab and the tab of the other electrode is a second tab. The first tab and the second tab are respectively disposed at opposite ends of the electrode assembly along the axial direction, and both the first tab and the second tab include a first tab winding portion and a second tab winding portion. Axially, both ends of the electrode assembly are provided with current collectors, and the current collectors at both ends of the electrode assembly are a first current collector and a second current collector, respectively. The first current collector is welded to the second tab winding portion of the first tab, but not to the first tab winding portion of the first tab; the second current collector is welded to the second tab winding portion of the second tab, but not to the first tab winding portion of the second tab.

[0044] During the thermal runaway of a cylindrical battery cell, the first electrode winding portions of both electrodes can be at least partially discharged to the outside of the casing through the venting channels, thereby helping to increase the venting rate, achieve directional pressure relief of the cylindrical battery cell, reduce the risk of cylindrical battery cell explosion, and improve the reliability of the cylindrical battery cell.

[0045] In some embodiments, the housing includes a first end wall, a second end wall, and a side wall, with the first end wall and the second end wall respectively disposed at both ends of the side wall along the axial direction. The cylindrical battery cell includes an electrode terminal disposed on the first end wall, a first tab being electrically connected to the electrode terminal through a first current collector, and a second tab being electrically connected to the first end wall through a second current collector and the side wall.

[0046] The electrode terminals and the first end wall can serve as two exposed electrodes of a cylindrical battery cell. The electrode terminals and the first end wall are located on the same side, which is beneficial for assembling multiple cylindrical battery cells into a group and simplifies the battery structure.

[0047] In some embodiments, the sidewall has an inwardly protruding protrusion, and the second current collector is connected to the protrusion.

[0048] In some embodiments, a portion of the second current collector is located on the side of the protrusion facing the second end wall and is connected to the protrusion.

[0049] In some embodiments, the second end wall is welded to the second current collector and electrically connected to the side wall.

[0050] The second end wall and the second current collector are arranged axially. Welding the second end wall and the second current collector together increases the welding area between the second end wall and the second current collector, thereby improving the current carrying capacity of the cylindrical battery cell.

[0051] In some embodiments, a pressure relief portion is provided on the second end wall.

[0052] By placing the pressure relief section on the second end wall, the thermal and gas pressure effects on the first end wall and electrode terminals can be reduced when high-temperature gases are discharged, thereby reducing the deformation of the first end wall, lowering the risk of the electrode terminals detaching from the first end wall, and improving the reliability of the cylindrical battery cell.

[0053] In some embodiments, the first electrode is a positive electrode and the second electrode is a negative electrode.

[0054] In some embodiments, the two electrodes include a positive electrode and a negative electrode, each comprising an electrode body and a tab. The tab of the positive electrode is not coated with an active material layer; and / or, the tab of the negative electrode is not coated with an active material layer.

[0055] In some embodiments, at least one electrode includes a positive electrode, which includes an electrode body, a tab, and an insulating layer. The tab of the positive electrode is not coated with an active material layer. In the axial direction, at least a portion of the insulating layer is disposed on the end region of the tab near the electrode body. By providing an insulating layer, the embodiments of this application can reduce the risk of burrs on the negative electrode contacting the tab and causing a short circuit, thereby improving reliability.

[0056] In some embodiments, at least one electrode has a winding start end and a winding end end at each end along the winding direction of the electrode assembly. A first electrode tab winding portion has a winding start end, and a second electrode tab winding portion has a winding end end. In the radial direction of the electrode assembly, the winding start end is closer to the central axis of the cylindrical battery cell than the winding end end. The portion of the first electrode tab winding portion near the winding start end has a first notch. The first notch extends through the winding start end along the winding direction and axially extends through the end face of the electrode tab opposite to the electrode body. In the radial direction of the electrode assembly, the first notch is located on the side of the first weld portion closer to the central axis of the cylindrical battery cell.

[0057] By setting a first notch, the mutual binding effect between the multi-layered structures of the first electrode winding portion can be weakened. In the event of thermal runaway of a cylindrical battery cell, the binding effect between the multi-layered structures of the first electrode winding portion is easily broken under air pressure. This allows at least a portion of the first electrode winding portion to be easily discharged through the exhaust channel under air pressure, increasing the exhaust rate, reducing the risk of cylindrical battery cell explosion, and improving the reliability of the cylindrical battery cell.

[0058] In some embodiments, at least one electrode has a winding start end and a winding end at both ends along the winding direction of the electrode assembly. A first electrode tab winding portion has a winding start end, and a second electrode tab winding portion has a winding end. In the radial direction of the electrode assembly, the winding start end is closer to the central axis of the cylindrical battery cell than the winding end. The portion of the second electrode tab winding portion near the winding end has a second notch, which extends through the winding end along the winding direction and axially through the end face of the electrode tab opposite to the electrode body.

[0059] In this embodiment of the application, by providing a second notch, the risk of the winding end of the second electrode winding portion coming into contact with other components due to tilting can be reduced, thereby reducing the risk of short circuit and improving the reliability of the cylindrical battery cell.

[0060] In some embodiments, in the radial direction of the electrode assembly, the first weld portion is closer to the central axis of the cylindrical cell relative to the second notch.

[0061] The embodiments of this application can reduce the risk of welding to the second notch groove during the welding process of the current collector and the electrode, thereby reducing the risk of incomplete welding and improving the welding strength between the current collector and the electrode.

[0062] In some embodiments, the current collector is provided with an exhaust port and a plurality of guide portions, the exhaust port extending axially; the plurality of guide portions are spaced apart around the outer periphery of the exhaust port. In a projection plane perpendicular to the axial direction, the orthographic projection of the exhaust port is located within the orthographic projection of the pressure relief portion, and the orthographic projection of the exhaust port at least partially overlaps with the orthographic projection of the first electrode lug winding portion.

[0063] When thermal runaway occurs in a cylindrical battery cell, the pressure relief section opens and forms an exhaust channel. Multiple guide sections guide the portion of the current collector component surrounding the exhaust hole to fold outward, thereby increasing the exhaust hole on the current collector component and reducing the obstruction of the current collector component to the first electrode winding portion. This facilitates at least a portion of the first electrode winding portion to be discharged to the outside of the casing through the exhaust hole and exhaust channel, improving exhaust efficiency and reducing the risk of cylindrical battery cell explosion.

[0064] In some embodiments, the guide extends to the vent hole, which helps to reduce the difficulty of the portion of the manifold surrounding the vent hole folding outward during depressurization.

[0065] In some embodiments, the guide portion is spaced apart from the wall of the vent hole, and the minimum distance between the guide portion and the wall of the vent hole is less than or equal to 10 mm. The portion of the manifold between the guide portion and the wall of the vent hole is smaller in size and has lower strength; during pressure relief, the portion of the manifold between the guide portion and the wall of the vent hole can break under pressure, thereby causing the portion of the manifold surrounding the vent hole to fold outward.

[0066] In some embodiments, the housing includes a weak portion surrounding the periphery of the pressure relief portion, at least a portion of which is configured to disconnect upon pressure relief to open the pressure relief portion. On a projection plane perpendicular to the axial direction, along the radial direction of the electrode assembly, the orthographic projection of the end of the guide portion away from the exhaust port is located outside or coincides with the orthographic projection of the weak portion.

[0067] After the weak point breaks, the pressure relief section opens and forms an exhaust channel. A portion of the current collector can be folded to the outside of the casing through the exhaust channel under the guidance of the guide section, thereby increasing the exhaust port size. In this embodiment, by setting the guide section at a position away from the exhaust port, the exhaust port size can be maximized. This facilitates at least a portion of the first electrode winding portion being discharged to the outside of the casing through the exhaust port and exhaust channel, improving exhaust efficiency and reducing the risk of cylindrical battery cell explosion.

[0068] In some embodiments, the electrode assembly has a central hole extending axially, a first electrode lug is disposed around the outer periphery of the central hole, and an exhaust port is axially opposite to and communicates with the central hole. In a projection plane perpendicular to the axial direction, the orthographic projection of the central hole lies within the orthographic projection of the pressure relief portion.

[0069] When thermal runaway occurs in a cylindrical battery cell, gas can act on the pressure relief section through the central hole and vent hole, thereby opening the pressure relief section and forming an exhaust channel. At least a portion of the first electrode winding section can easily be discharged to the outside of the conductive shell under the action of gas pressure through the vent hole and exhaust channel, increasing the exhaust rate, reducing the risk of cylindrical battery cell explosion, and improving the reliability of the cylindrical battery cell.

[0070] In some embodiments, both electrodes include a first electrode winding portion. A gap is provided between the electrode bodies of the two first electrode winding portions.

[0071] By setting a gap, the pressure between the two electrode bodies can be reduced, and the binding effect of the two electrode bodies on each other can be weakened. When thermal runaway occurs in a cylindrical battery cell, the two first electrode windings can easily separate under the action of air pressure and be discharged to the outside of the casing at least partially through the exhaust channel, thereby increasing the exhaust rate, reducing the risk of cylindrical battery cell explosion, and improving the reliability of cylindrical battery cell.

[0072] In some embodiments, the radial dimension D3 of at least a portion of the gap is 5 μm-60 μm.

[0073] In this embodiment, the radial dimension D3 of the gap is limited to greater than or equal to 5 μm. This reduces the pressure between the electrode bodies of the two electrodes and weakens their binding effect on each other, allowing the wound portions of the two first electrodes to be easily discharged to the outside of the casing under air pressure. In another embodiment, the radial dimension D3 of the gap is limited to less than or equal to 60 μm. This shortens the ion migration path between the active material layers of the positive and negative electrodes, reduces the internal resistance of the cylindrical battery cell, reduces heat generation, and minimizes the impact of the gap on energy density.

[0074] In some embodiments, the surface of the electrode body is provided with a plurality of electrode recesses. At least a portion of the plurality of electrode recesses is formed in the first electrode winding portion.

[0075] By setting the electrode recess, the pressure between the electrode bodies of the two electrodes can be reduced, and the binding effect of the electrode bodies of the two electrodes on each other can be weakened. When thermal runaway occurs in the cylindrical battery cell, the two first electrode winding parts can easily separate under the action of air pressure and be discharged to the outside of the casing at least partially through the exhaust channel, thereby increasing the exhaust rate, reducing the risk of cylindrical battery cell explosion, and improving the reliability of cylindrical battery cell.

[0076] In some embodiments, the electrode recess is formed in the active material layer, which can reduce the impact of the electrode recess on the current-carrying capacity of the electrode body.

[0077] In some embodiments, the electrode recess extends axially through the electrode body to increase the gap between the electrode bodies of the two electrodes, reduce the binding effect of the electrode bodies of the two electrodes on each other, and facilitate the two first electrode winding portions to extend to the outside of the outer shell.

[0078] In some embodiments, a plurality of electrode recesses are spaced apart along the winding direction of the electrode assembly. The plurality of electrode recesses can further reduce the binding effect of the electrode bodies of the two electrodes on each other, facilitating the extension of the two first electrode winding portions to the outside of the housing.

[0079] In some embodiments, at least one electrode includes a positive electrode, which comprises an electrode body and a tab. The active material layer of the positive electrode includes a positive 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.

[0080] The higher nickel content in the active material layer of the positive electrode allows for greater energy storage, significantly improving the energy density of the cylindrical battery cell. As the nickel content increases, the amount of cobalt used decreases. Cobalt is a scarce and expensive metal; reducing its use lowers the cost of the cylindrical battery cell. Cylindrical battery cells with higher nickel content exhibit higher conductivity, meaning they can operate at higher power levels, supporting fast charging and high-current discharge. In low-temperature environments, cylindrical battery cells with higher nickel content show less capacity decay, maintaining higher discharge efficiency and enabling normal operation of electrical equipment in cold conditions. However, cylindrical battery cells with higher nickel content have relatively poor thermal stability, generating more heat and gas during thermal runaway. At least a portion of the first electrode winding can be released to the outside of the casing through the exhaust channel under pressure, thereby increasing the exhaust rate. This embodiment of the application can rapidly release the high-temperature gas generated by the nickel cylindrical battery cell during thermal runaway, reducing the risk of explosion and improving both the energy density and reliability of the cylindrical battery cell. In this embodiment, b is set to less than or equal to 0.95, which can reduce the risk of explosion when a cylindrical battery cell experiences thermal runaway.

[0081] In some embodiments, the cylindrical battery cell further includes an electrolyte contained within a housing. 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.

[0082] 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, and thus improving the rate performance of the cylindrical battery cell. 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 components. This further improves the fast charging and discharging capability of the cylindrical battery cell, thereby enhancing its rate performance.

[0083] Chain-like ester solvents face the problem of decomposition and gas generation at high temperatures. In the event of thermal runaway in a cylindrical battery, at least a portion of the first electrode winding can be released to the outside of the casing, thereby promptly releasing the gas generated by the decomposition of the chain-like ester solvent and reducing the risk of explosion.

[0084] In this embodiment, the mass percentage of the chain ester solvent is set to less than or equal to 76.5 wt%, which can limit the decomposition and gas generation of the cylindrical battery cell during normal charge and discharge cycles, thereby reducing the impact of the chain ester solvent on the internal pressure of the casing, reducing casing deformation, reducing the risk of cylindrical battery cell failure, and improving reliability.

[0085] In some embodiments, the height of the casing is 50 mm to 150 mm. Setting the casing height to be greater than or equal to 50 mm can increase the capacity and energy density of the cylindrical battery cell; in the event of thermal runaway of the cylindrical battery, at least a portion of the first electrode winding portion can be discharged to the outside of the casing, thereby reducing the impact of increasing the casing height on the venting rate. Setting the height of the cylindrical battery cell to be less than or equal to 150 mm reduces the risk of the cylindrical battery cell exploding.

[0086] In some embodiments, the diameter of the casing is 35 mm to 80 mm. Setting the casing diameter to be greater than or equal to 35 mm can increase the capacity and energy density of the cylindrical battery cell; in the event of thermal runaway of the cylindrical battery, at least a portion of the first electrode winding portion can be discharged to the outside of the casing, thereby reducing the impact of increasing the casing diameter on the venting rate. Setting the diameter of the cylindrical battery cell to be less than or equal to 80 mm limits the amount of gas generated by the cylindrical battery cell during thermal runaway, reducing the risk of explosion.

[0087] Secondly, embodiments of this application provide a battery device comprising a plurality of cylindrical battery cells provided according to any embodiment of the first aspect.

[0088] Thirdly, embodiments of this application provide an electrical device including a battery device according to any embodiment of the second aspect, the battery device being used to provide electrical energy. Attached Figure Description

[0089] 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.

[0090] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0091] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application;

[0092] Figure 3 is a schematic diagram of the battery module shown in Figure 2;

[0093] Figure 4 is a schematic diagram of the structure of a cylindrical battery cell in some embodiments of this application;

[0094] Figure 5 is an exploded schematic diagram of a cylindrical battery cell in some embodiments of this application;

[0095] Figure 6 is a cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of this application;

[0096] Figure 7 is an enlarged view of Figure 6 at box A;

[0097] Figure 8 is an enlarged view of the area in box B of Figure 6;

[0098] Figure 9 is a cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0099] Figure 10 is a schematic diagram of the electrode assembly and current collector of a cylindrical battery cell provided in some embodiments of this application after welding;

[0100] Figure 11 is an enlarged view of Figure 10 at the boxed area;

[0101] Figure 12 is a schematic diagram of the positive electrode sheet of a cylindrical battery cell provided in some embodiments of this application after being flattened;

[0102] Figure 13 is a cross-sectional view along the CC direction shown in Figure 12;

[0103] Figure 14 is a schematic diagram of the negative electrode sheet of a cylindrical battery cell provided in some embodiments of this application after being flattened;

[0104] Figure 15 is a cross-sectional view along the DD direction shown in Figure 14;

[0105] Figure 16 is a partial schematic diagram of the electrode assembly and current collector of a cylindrical battery cell provided in some other embodiments of this application;

[0106] Figure 17 is a schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0107] Figure 18 is a schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application before the tab is bent.

[0108] Figure 19 is a schematic diagram of the electrode of a cylindrical battery cell provided in some embodiments of this application in a flattened state;

[0109] Figure 20 is an enlarged view of Figure 19 at the circular frame;

[0110] Figure 21 is a schematic diagram of the electrode assembly and current collector of a cylindrical battery cell provided in some embodiments of this application after welding;

[0111] Figure 22 is an enlarged view of Figure 21 at the boxed area;

[0112] Figure 23 is a partial schematic diagram of the electrode assembly and current collector of a cylindrical battery cell provided in some embodiments of this application after welding;

[0113] Figure 24 is a partial cross-sectional schematic diagram of a cylindrical battery cell provided in some other embodiments of this application;

[0114] Figure 25 is an enlarged view of Figure 24 at the boxed area;

[0115] Figure 26 is a schematic diagram of the current collector of a cylindrical battery cell provided in some embodiments of this application;

[0116] Figure 27 is a schematic diagram of the electrode sheet of a cylindrical battery cell provided in some embodiments of this application after being flattened;

[0117] Figure 28 is a partial sectional view along the EE direction shown in Figure 27;

[0118] Figure 29 is a partial cross-sectional schematic diagram of a cylindrical battery cell provided in some other embodiments of this application.

[0119] Explanation of reference numerals in the attached drawings: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing; 5b. Second housing; 6. Battery module; 7. Cylindrical battery cell; 7a. First electrode lead-out portion; 7b. Second electrode lead-out portion; 10. Electrode assembly; 11. Electrode sheet; 111. Electrode sheet body; 1111. Active material layer; 11111. Electrode sheet recess; 1112. Current collector body; 1113. First electrode sheet body winding portion; 1114. Second electrode sheet body winding portion; 112. Tab; 1121. First tab winding portion; 11211. First coil portion; 11212. Second coil portion; 1122. Second tab winding portion; 1123. Section; 11231. Bending section; 11 232. First bend; 11233. Second bend; 1124. Cut-off groove; 11241. Groove bottom; 1124a. First set of cut-off grooves; 1124b. Second set of cut-off grooves; 1125. Transition connection; 112a. First electrode tab; 112b. Second electrode tab; 113. Insulating layer; 11a. Positive electrode; 11b. Negative electrode; 12. Isolator; 13. First electrode winding section; 14. Second electrode winding section; 15. Center hole; 20. Outer shell; 20a. Second end wall; 21. Housing; 211. First end wall; 212. Side wall; 2121. Protrusion; 2122. Third recess; 2123. Press-fit part; 22. End cap; 30. Electrode terminal; 31. Terminal recess; 40. Current collector; 40a. First current collector; 40b. Second current collector; 41. Exhaust vent; 42. Guide part; 43. Second recess; 50. Cover plate; 60. Pressure relief mechanism; 61. Pressure relief part; 62. Weak part; 63. First recess; 70. Insulating member; C1, winding coil; E1, winding start end; E2, winding end end; E3, first projection end point; E4, second projection end point; E5, third projection end point; E6, fourth projection end point; G1, first notch; G2, second notch; G3, gap; P1, first arc; P2, second arc; P3, third arc; P4, fourth arc; P5, central axis; Q, overlapping area; Q1, first transverse area; Q2, second transverse area; W1, first weld; W2, second weld; W3, third weld; R, radial; V, winding direction; X, length direction; Y, width direction; Z, axial. Detailed Implementation

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] In this application, "multiple" means two or more (including two).

[0127] Cylindrical battery cells can be cylindrical secondary batteries. Secondary batteries are battery cells that can be recharged after discharge to activate the active materials and continue to be used.

[0128] A battery device can refer to a single physical module comprising one or more cylindrical battery cells to provide higher voltage and capacity.

[0129] A cylindrical battery cell includes an electrode assembly and a housing for containing the electrode assembly. The electrode assembly typically includes a positive electrode, a negative electrode, and a separator that separates the positive and negative electrodes.

[0130] The cylindrical battery cell may also include a pressure relief section, which can be actuated to release the internal pressure or temperature when the internal pressure or temperature of the cylindrical battery cell reaches a predetermined threshold, thereby reducing the risk of the cylindrical battery cell exploding.

[0131] Electrode assemblies typically include tabs that allow current to be drawn from the electrode assembly. Cylindrical cell units usually have current collectors that direct current from the tabs to the electrode lead-out structures of the cylindrical cell. In related technologies, the current collectors are typically welded to the tabs.

[0132] During thermal runaway of a cylindrical battery cell, the pressure relief section at least partially opens and forms an exhaust channel, thereby venting the high-temperature gas inside the cylindrical battery cell to the outside of the casing. However, the current collector is welded to the tab, which has a strong binding effect on the electrode assembly, keeping the electrode assembly inside the casing during the emission of high-temperature gas. This restricts the emission of high-temperature gas by the electrode assembly, affecting the pressure relief rate of the cylindrical battery cell.

[0133] In view of this, the present application provides a technical solution in which a portion of the tab near the winding center is not welded to the current collector and is opposite to the pressure relief part, so that when the pressure relief part is opened and an exhaust channel is formed, a portion of the electrode sheet can be discharged to the outside of the casing through the exhaust channel, thereby reducing the obstruction of the electrode assembly to high-temperature gas, improving the pressure relief rate of the cylindrical battery cell, and improving the reliability of the cylindrical battery cell.

[0134] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0135] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0136] As shown in Figure 1, 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.

[0137] 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.

[0138] 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.

[0139] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application.

[0140] In some embodiments, the battery device 2 may include one or more battery cell assemblies for providing voltage and capacity.

[0141] A battery cell assembly may include multiple cylindrical battery cells, which are connected in series, parallel, or mixed connection via a busbar. Mixed connection refers to multiple cylindrical battery cells being connected in both series and parallel connections.

[0142] Cylindrical battery cells can be rechargeable battery cells, which are battery cells that can be recharged after being discharged to activate the active materials and continue to be used.

[0143] 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.

[0144] 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 into a single module. As an example, the battery module 6 can be formed by binding multiple cylindrical battery cells together with cable ties.

[0145] 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.

[0146] In some embodiments, the housing 5 is used to house cylindrical battery cells, and the housing 5 can have various structures.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] In some embodiments, the battery device 2 may be an energy storage device.

[0151] 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.

[0152] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0153] Figure 3 is a schematic diagram of the battery module shown in Figure 2.

[0154] In some embodiments, as shown in FIG3, there are multiple cylindrical battery cells 7, which are first connected in series, parallel, or mixed to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or mixed to form a whole and housed in a casing.

[0155] 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.

[0156] Figure 4 is a structural schematic diagram of a cylindrical battery cell in some embodiments of this application; Figure 5 is an exploded schematic diagram of a cylindrical battery cell in some embodiments of this application.

[0157] Referring to Figures 4 and 5, an embodiment of this application provides a cylindrical battery cell 7, which includes a housing 20 and an electrode assembly 10, at least a portion of which is housed within the housing 20.

[0158] The outer casing 20 may be a hollow structure, with an internal space for accommodating the electrode assembly 10 and the electrolyte. For example, the outer casing 20 of the cylindrical battery cell 7 is a cylindrical casing.

[0159] In some embodiments, the housing 20 may be a metal housing, such as a steel housing, an aluminum housing, a composite metal housing (e.g., a copper-aluminum composite housing), or other metal housings. Alternatively, the housing may also be a non-metallic housing, such as a plastic housing (e.g., polypropylene).

[0160] In some embodiments, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening, and the end cap 22 being connected to the housing 21 and covering the opening;

[0161] 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, electrolyte, and other components.

[0162] 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 battery cell.

[0163] The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0164] 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 battery cell can have higher structural strength and improve reliability.

[0165] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0166] 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.

[0167] In some embodiments, the housing 20 includes a first end wall 211, a second end wall 20a, and a side wall 212, wherein the first end wall 211 and the second end wall 20a are respectively disposed at both ends of the side wall 212 along the axial direction Z.

[0168] For example, the housing 21 includes a sidewall 212. At least one of the first end wall 211 and the second end wall 20a is formed independently of the sidewall 212.

[0169] In some examples, the first end wall 211 and the side wall 212 are integrally formed. Optionally, the housing 21 includes the first end wall 211 and the side wall 212. In other examples, the first end wall 211 and the side wall 212 are formed independently and are fixedly connected by welding, snap-fitting, bonding or other means. Optionally, the housing 21 includes the side wall 212 and the first end wall 211 is an end cap 22.

[0170] In some examples, the second end wall 20a is integrally formed with the side wall 212. Optionally, the housing 21 includes the second end wall 20a and the side wall 212. In other examples, the second end wall 20a and the side wall 212 are formed independently and are fixedly connected by welding, snap-fitting, bonding or other means. Optionally, the housing 21 includes the side wall 212 and the second end wall 20a is an end cap 22.

[0171] In some embodiments, the housing 21 includes an integrally formed first end wall 211 and side wall 212, and the second end wall 20a is an end cap 22.

[0172] Electrode assembly 10 is the component in the cylindrical battery cell 7 where the electrochemical reaction takes place. Electrode assembly 10 can be entirely housed within housing 20 or partially housed within housing 20. For example, electrode assembly 10 includes tabs, a portion of which can extend outside housing 20.

[0173] Optionally, the electrode assembly 10 is entirely housed within the housing 20.

[0174] In some embodiments, the electrode assembly 10 includes two tabs 112 with opposite polarities, one tab 112 being a first tab 112a and the other tab 112 being a second tab 112b. One of the first tab 112a and the second tab 112b is a positive tab, and the other is a negative tab.

[0175] In some embodiments, along the axial direction Z of the cylindrical battery, the first tab 112a and the second tab 112b 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. Optionally, the first tab 112a and the second tab 112b are disposed at opposite ends of the electrode assembly 10 along the axial direction Z.

[0176] In some embodiments, the cylindrical battery cell 7 includes a first electrode lead-out portion 7a and a second electrode lead-out portion 7b, wherein the first electrode lead-out portion 7a is electrically connected to a first tab 112a, and the second electrode lead-out portion 7b is electrically connected to a second tab 112b.

[0177] The first electrode lead-out portion 7a and the second electrode lead-out portion 7b are insulated from each other.

[0178] The first electrode lead-out portion 7a and the second electrode lead-out portion 7b are used to connect to an external circuit to enable charging or discharging of the cylindrical battery cell 7. Exemplarily, when multiple cylindrical battery cells 7 are assembled into a group, the first electrode lead-out portion 7a and the second electrode lead-out portion 7b are used to connect to a busbar component.

[0179] The first electrode lead-out portion 7a can be an electrode terminal 30 disposed on the housing 20. The electrode terminal 30 is formed independently of the housing 20 and is assembled together during the production process of the cylindrical battery cell 7. As an example, the electrode terminal 30 is insulatedly disposed on the end cap 22 or the housing 21.

[0180] Alternatively, the first electrode lead-out portion 7a may also be part of the housing 20. For example, the first electrode lead-out portion 7a may be an end wall (first end wall 211 or second end wall 20a) of the housing 20.

[0181] The second electrode lead-out portion 7b can be an electrode terminal 30 disposed on the housing 20. Alternatively, the second electrode lead-out portion 7b can be part of the housing 20. For example, the second electrode lead-out portion 7b can be an end wall (first end wall 211 or second end wall 20a) of the housing 20.

[0182] In some embodiments, the first electrode lead-out portion 7a and the second electrode lead-out portion 7b are located on the same side of the electrode assembly 10 along the axial direction Z of the cylindrical battery cell 7.

[0183] When multiple cylindrical battery cells 7 are assembled into a group, the first electrode lead-out portion 7a and the second electrode lead-out portion 7b of the multiple cylindrical battery cells 7 can be arranged on the same side, which facilitates the connection between the current collector and the first electrode lead-out portion 7a and the second electrode lead-out portion 7b, and simplifies the battery structure.

[0184] In some embodiments, the second electrode lead-out portion 7b may be the first end wall 211.

[0185] In some embodiments, the first end wall 211 is provided with an electrode lead-out hole, and the first electrode lead-out portion 7a includes an electrode terminal 30 disposed in the electrode lead-out hole. The electrode terminal 30 is insulated from the first end wall 211.

[0186] In some embodiments, the electrode terminal 30 is riveted to the first end wall 211.

[0187] In some examples, the electrode terminal 30 can be riveted to the first end wall 211 from the outside. For example, the electrode terminal 30 can first pass through the electrode lead hole from the inside of the first end wall 211, and then be pressed from the outside of the first end wall 211 to form a flange structure, thereby riveting the electrode terminal 30 to the first end wall 211.

[0188] In other examples, the electrode terminal 30 can be riveted to the first end wall 211 from the inside. For example, the electrode terminal 30 can first pass through the electrode lead hole from the outside of the first end wall 211, and then be pressed from the inside of the first end wall 211 to form a flange structure, thereby riveting the electrode terminal 30 to the first end wall 211.

[0189] In some embodiments, the cylindrical battery cell 7 includes a current collector 40, which is electrically connected to the tab 112.

[0190] There may be one or two current collectors 40. For example, there may be one current collector 40, which may be electrically connected to the first tab 112a or the second tab 112b; or there may be two current collectors 40, which may be electrically connected to the first tab 112a and the second tab 112b respectively.

[0191] In some embodiments, the current collector 40 is welded to the tab 112.

[0192] In some embodiments, the cylindrical battery cell 7 includes two current collectors 40, which are a first current collector 40a and a second current collector 40b.

[0193] The first current collector 40a electrically connects the first tab 112a to the first electrode lead-out portion 7a, and the second current collector 40b electrically connects the second tab 112b to the second electrode lead-out portion 7b.

[0194] In some embodiments, electrode terminals 30 are welded to the first current collector 40a.

[0195] In some embodiments, the electrode terminal 30 is provided with a terminal recess 31. The bottom wall of the terminal recess 31 is welded to the first current collector 40a.

[0196] The terminal recess 31 can be provided on the side of the electrode terminal 30 facing the first current collector 40a, or it can be provided on the side of the electrode terminal 30 facing away from the first current collector 40a.

[0197] By providing the terminal recess 31, the thickness of the bottom wall of the terminal recess 31 can be reduced, the power required to weld the electrode terminal 30 to the first current collector 40a from the outside can be reduced, the risk of welding particles falling into the casing 20 can be reduced, and the reliability of the cylindrical battery cell 7 can be improved.

[0198] In some embodiments, the electrode terminal 30 has a terminal recess 31 on the side opposite to the first current collector 40a.

[0199] In some embodiments, the electrode terminal 30 has a terminal recess 31 on the side facing the first current collector 40a, and another terminal recess 31 on the side of the electrode terminal 30 away from the first current collector 40a; the corresponding portions of the bottom surfaces of the two terminal recesses 31 are welded to the first current collector 40a.

[0200] In some embodiments, the bottom wall of the terminal recess 31 is provided with a through hole, which can be used to inject electrolyte.

[0201] In some embodiments, the cylindrical battery cell 7 further includes a cover plate 50, which is connected to the electrode terminal 30 and serves to separate the through hole from the external space of the cylindrical battery cell 7.

[0202] In some embodiments, at least a portion of the cover plate 50 is received in the terminal recess 31.

[0203] In some embodiments, the first electrode lead-out portion 7a includes an electrode terminal 30 and a cover plate 50.

[0204] In some embodiments, the second tab 112b is connected to the second current collector 40b. At least one of the sidewall 212 and the second endwall 20a is connected to the second current collector 40b such that the sidewall 212 electrically connects the first endwall 211 and the second current collector 40b.

[0205] In some examples, the second current collector 40b is electrically connected to the sidewall 212, and the second tab 112b is electrically connected to the first end wall 211 through the second current collector 40b and the sidewall 212. The second current collector 40b may be electrically connected to the second end wall 20a or insulated from the second end wall 20a.

[0206] In other examples, the second current collector 40b is electrically connected to the second end wall 20a, and the second tab 112b is electrically connected to the first end wall 211 via the second current collector 40b, the second end wall 20a, and the side wall 212. Optionally, the second current collector 40b is welded to the second end wall 20a.

[0207] In some embodiments, the housing 20 is provided with a pressure relief portion 61. As an example, the pressure relief portion 61 may be provided on the first end wall 211, the second end wall 20a, or the side wall 212.

[0208] As an example, the pressure relief section 61 is configured to at least partially open and form an exhaust channel during pressure relief. For instance, the pressure relief section 61 can open and form an exhaust channel when the pressure value inside the housing 20 reaches a threshold. This threshold design varies depending on design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the cylindrical battery cell 7.

[0209] In the event of thermal runaway of the cylindrical battery cell 7, the high-temperature gas inside the casing 20 can be discharged to the outside through the exhaust channel. By providing the pressure relief section 61, the cylindrical battery cell 7 can be depressurized and de-temperatureed under controllable pressure or temperature, thereby reducing the risk of potentially more serious accidents.

[0210] In some embodiments, the housing 20 is provided with a pressure relief portion 61 at at least one end along the axial direction Z.

[0211] In some examples, a pressure relief portion 61 is provided at one end of the housing 20 along the axial direction Z. For example, the pressure relief portion 61 is provided on the first end wall 211 or the second end wall 20a.

[0212] In other examples, pressure relief portions 61 are provided at both ends of the housing 20 along the axial direction Z. For example, the first end wall 211 is provided with a pressure relief portion 61, and the second end wall 20a is also provided with a pressure relief portion 61.

[0213] In some embodiments, a pressure relief portion 61 is disposed on the second end wall 20a.

[0214] In some examples, the pressure relief portion 61 and the second end wall 20a are independently formed components, which can be connected by welding, bonding or other means. In other examples, the pressure relief portion 61 and the second end wall 20a can be integrally formed components; in other words, the pressure relief portion 61 can form part of the second end wall 20a.

[0215] Figure 6 is a cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of this application; Figure 7 is an enlarged schematic diagram of Figure 6 at box A; Figure 8 is an enlarged schematic diagram of Figure 6 at box B; Figure 9 is a cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application; Figure 10 is a schematic diagram of the electrode assembly and current collector of a cylindrical battery cell provided in some embodiments of this application after welding; Figure 11 is an enlarged schematic diagram of Figure 10 at the box; Figure 12 is a schematic diagram of the positive electrode sheet of a cylindrical battery cell provided in some embodiments of this application after flattening; Figure 13 is a cross-sectional schematic diagram of Figure 12 along the CC direction; Figure 14 is a schematic diagram of the negative electrode sheet of a cylindrical battery cell provided in some embodiments of this application after flattening; Figure 15 is a cross-sectional schematic diagram of Figure 14 along the DD direction.

[0216] Referring to Figures 5 to 15, this application embodiment provides a cylindrical battery cell 7, which includes a housing 20, an electrode assembly 10, and a current collector 40. The housing 20 has a pressure relief portion 61 at at least one end along the axial direction Z of the cylindrical battery cell 7. At least a portion of the electrode assembly 10 is disposed within the housing 20. The electrode assembly 10 has a wound structure and includes two electrodes 11 with opposite polarities. At least one electrode 11 includes an electrode body 111 and a tab 112 arranged along the axial direction Z. At least a portion of the electrode body 111 is coated with an active material layer 1111, and at least a portion of the tab 112 is not coated with the active material layer 1111. At least a portion of the current collector 40 is disposed within the housing 20.

[0217] The electrode tab 112 includes a first electrode tab winding portion 1121 and a second electrode tab winding portion 1122 located outside the first electrode tab winding portion 1121. The current collector 40 is welded to the second electrode tab winding portion 1122 and forms a first welding portion W1. The current collector 40 is not welded to the first electrode tab winding portion 1121.

[0218] The electrode 11 includes a first electrode winding portion 13, and a first electrode ear winding portion 1121 is formed on a part of the first electrode winding portion 13. On a projection plane perpendicular to the axial direction Z, the orthographic projection of the first electrode winding portion 13 at least partially overlaps with the orthographic projection of the pressure relief portion 61. The pressure relief portion 61 is configured to at least partially open and form an exhaust channel when pressure is released. At least part of the first electrode winding portion 13 is released to the outside of the housing 20 through the exhaust channel.

[0219] As an example, two pole pieces 11 with opposite polarities can be wound along the winding direction V.

[0220] In some examples, tab 112 may be uncoated with active material layer 1111; in other examples, a portion of tab 112 may be uncoated with active material layer 1111 and another portion may be coated with active material layer 1111, and the uncoated portion of tab 112 may be welded to current collector 40.

[0221] As an example, tab 112 can be a metal foil. Tab 112 can be made of pure metal, alloy, or surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver.

[0222] As an example, the electrode body 111 may include a current collector 1112 and an active material layer 1111, wherein the active material layer 1111 is disposed on at least one surface of the current collector 1112. Optionally, both surfaces of the current collector 1112 are provided with the active material layer 1111.

[0223] The tab 112 can be connected to the current collector 1112. In some examples, the tab 112 and the current collector 1112 can be formed independently and connected by welding or other means; in other examples, the tab 112 and the current collector 1112 are integrally formed.

[0224] The current collector 1112 can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. 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.).

[0225] In some examples, the positive electrode 11a includes an electrode body 111 and a tab 112.

[0226] Optionally, the active material layer 1111 of the positive electrode 11a 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 positive electrode active materials for batteries 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 0.2Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0227] Optionally, the current collector 1112 and the tab 112 of the positive electrode 11a are integrally formed; optionally, the current collector 1112 and the tab 112 of the positive electrode 11a can both be made of aluminum.

[0228] In other examples, the negative electrode 11b includes an electrode body 111 and an electrode tab 112.

[0229] Optionally, the active material layer 1111 of the negative electrode 11b includes a negative electrode active material. The negative electrode active material may be a negative electrode active material known in the art for use in cylindrical battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for cylindrical battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0230] Optionally, the current collector 1112 and the tab 112 of the negative electrode 11b are integrally formed; optionally, the current collector 1112 and the tab 112 of the negative electrode 11b can both be made of copper.

[0231] In some other examples, the positive electrode 11a includes an electrode body 111 and a tab 112, and the negative electrode 11b includes an electrode body 111 and a tab 112.

[0232] For example, the tab 112 is wound along the winding direction V. In the winding direction V, the first tab winding portion 1121 can be a continuous structure or a discontinuous structure. In the winding direction V, the second tab winding portion 1122 can be a continuous structure or a discontinuous structure.

[0233] The connection point between the second electrode ear winding portion 1122 and the electrode body 111 is located outside the connection point between the first electrode ear winding portion 1121 and the electrode body 111.

[0234] The first welding part W1 can be one or more.

[0235] For example, the first electrode lug winding portion 1121 may be connected to the first welding portion W1 at one end near the second electrode lug winding portion 1122 along the winding direction V of the electrode assembly 10.

[0236] For example, the position of the first welding portion W1 can define the first electrode winding portion 1121 and the second electrode winding portion 1122. For instance, the position where the electrode 112 first reaches the first welding portion W1 from the inside out along the winding direction V can be the interface between the first electrode winding portion 1121 and the second electrode winding portion 1122.

[0237] After the electrode 11 is flattened (both the electrode body 111 and the electrode tab 112 are flattened), the first electrode tab winding portion 1121 and the second electrode tab winding portion 1122 can be arranged along the length direction X of the electrode 11. The interface between the first electrode tab winding portion 1121 and the second electrode tab winding portion 1122 can be parallel to the width direction Y and the thickness direction of the electrode 11. This interface can be adjacent to the portion of the electrode tab 112 used to form the first weld portion W1. For example, in Figures 12 and 14, the portion of the second electrode tab winding portion 1122 used to form the first weld portion W1 is shown with a dashed box.

[0238] In the winding direction V, the length of the first electrode ear winding portion 1121 can be greater than, equal to or less than the length of the second electrode ear winding portion 1122. In other words, after the electrode sheet 11 is flattened, the length of the first electrode ear winding portion 1121 can be greater than, equal to or less than the length of the second electrode ear winding portion 1122.

[0239] As an example, the electrode body 111 includes a first electrode body winding portion 1113 and a second electrode body winding portion 1114 disposed along the winding direction V, with the second electrode body winding portion 1114 located outside the first electrode body winding portion 1113. A first electrode ear winding portion 1121 extends from the end of the first electrode body winding portion 1113 along the axial direction Z, and a second electrode ear winding portion 1122 extends from the end of the second electrode body winding portion 1114 along the axial direction Z. The first electrode body winding portion 13 includes the first electrode body winding portion 1113 and the first electrode ear winding portion 1121.

[0240] The interface between the first electrode ear winding portion 1121 and the second electrode ear winding portion 1122 corresponds to the interface between the first electrode body winding portion 1113 and the second electrode body winding portion 1114. After the electrode 11 is flattened, the interface between the first electrode ear winding portion 1121 and the second electrode ear winding portion 1122 and the interface between the first electrode body winding portion 1113 and the second electrode body winding portion 1114 are in the same plane.

[0241] On a projection plane perpendicular to the Z-axis, the orthographic projection of the first electrode winding portion 13 may be partially or completely located within the orthographic projection of the pressure relief portion 61. Optionally, on a projection plane perpendicular to the Z-axis, the orthographic projection of the first electrode winding portion 13 may be partially located within the orthographic projection of the pressure relief portion 61.

[0242] On the projection plane perpendicular to the Z-axis, the orthographic projection of the second pole ear winding portion 1122 and the orthographic projection of the pressure relief portion 61 may or may not overlap.

[0243] After the pressure relief section 61 is at least partially opened and forms an exhaust channel, the portion of the first electrode winding section 13 that is discharged outside the housing 20 through the exhaust channel can be connected to the portion of the electrode 11 remaining inside the housing 20, or it can be separated from the portion of the electrode 11 remaining inside the housing 20.

[0244] In this embodiment, when the cylindrical battery cell 7 experiences thermal runaway due to an unexpected event such as a short circuit, the pressure inside the casing 20 increases, the pressure relief section 61 opens, and an exhaust channel is formed, allowing the high-temperature gas inside the casing 20 to be discharged through the exhaust channel. The current collector 40 is not welded to the first electrode lug winding portion 1121, thereby reducing the binding effect of the current collector 40 on the first electrode lug winding portion 1121, i.e., reducing the binding effect of the current collector 40 on the first electrode winding portion 13. During the thermal runaway of the cylindrical battery cell 7, at least a portion of the first electrode winding portion 13 can be released to the outside of the casing 20 through the exhaust channel under the action of gas pressure. On the other hand, during the process of at least a portion of the first electrode winding portion 13 being ejected through the exhaust channel, fragments of the electrode 11, high-temperature gas, electrolyte, and other substances can also be ejected along with the first electrode winding portion 13, thereby rapidly relieving pressure. On the other hand, the first electrode winding portion 13 is located in the middle of the electrode assembly 10. After at least a portion of the first electrode winding portion 13 is discharged through the exhaust channel, a channel opposite to the exhaust channel is formed in the middle of the electrode assembly 10, which is beneficial for the discharge of high-temperature gas. After at least a portion of the first electrode winding portion 13 is discharged through the exhaust channel, the electrode 11 remaining in the housing 20 becomes more porous, which facilitates the flow of gas between the electrode 11. In summary, the embodiments of this application can help increase the exhaust rate, reduce the risk of explosion of the cylindrical battery cell 7, and improve the reliability of the cylindrical battery cell 7 in the event of thermal runaway of the cylindrical battery.

[0245] In some embodiments, the electrode assembly 10 further includes a separator 12 disposed between the positive electrode 11a and the negative electrode 11b. The separator 12 serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0246] The positive electrode 11a, the negative electrode 11b, and the separator 12 are wound along the winding direction V and form a cylindrical winding structure.

[0247] In some embodiments, the separator 12 is a separator membrane. The separator membrane of this application can be any known porous structure separator membrane with good chemical and mechanical stability.

[0248] 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 12 can be a single component located between the positive electrode 11a and the negative electrode 11b, or it can be attached to the surface of the positive electrode 11a or the surface of the negative electrode 11b. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0249] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte, which acts as a conductor of ions between the positive electrode 11a and the negative electrode 11b. The electrolyte used in this application can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0250] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0251] 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.

[0252] 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.

[0253] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of cylindrical battery cells, such as additives that improve the overcharge / fast charge performance of cylindrical battery cells, additives that improve the high-temperature performance of cylindrical battery cells, additives that improve the low-temperature performance of cylindrical battery cells, etc.

[0254] In some embodiments, the gel electrolyte comprises a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0255] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0256] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0257] 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.

[0258] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0259] In some embodiments, the tab 112 may be cylindrical.

[0260] In some embodiments, a portion of the tab 112 is bent to form an overlapping region Q, in which the tab 112 has a multi-layered structure overlapping in the axial direction Z. At least a portion of the overlapping region Q is formed in the second tab winding portion 1122. The overlapping region Q of the second tab winding portion 1122 is welded to the current collector 40 to form a first weld portion W1.

[0261] Welding the overlapping area Q to the current collector 40 can reduce the risk of poor welding and increase the welding area between the tab 112 and the current collector 40, thereby improving the current carrying capacity.

[0262] In some embodiments, a portion of the overlapping region Q is formed in the first electrode loop winding portion 1121.

[0263] In some embodiments, the tab 112 is bent and forms an overlapping region Q by a flattening or smoothing process.

[0264] In some embodiments, in the second electrode ear winding portion 1122, the number of overlapping layers in the overlapping region Q is greater than or equal to 2, and optionally, the number of overlapping layers in the overlapping region Q is greater than or equal to 5.

[0265] In some embodiments, in the first electrode winding portion 1121, the number of overlapping layers in the overlapping region Q is greater than or equal to 2, and optionally, the number of overlapping layers in the overlapping region Q is greater than or equal to 5.

[0266] In some embodiments, there are multiple first weld portions W1. Optionally, the multiple first weld portions W1 are arranged at circumferential intervals along the cylindrical battery cell 7.

[0267] In some embodiments, a plurality of first welded portions W1 are arranged radially.

[0268] In one embodiment, the first weld portion W1 extends radially R along the electrode assembly 10.

[0269] In some embodiments, the electrode 11 includes a second electrode winding portion 14, which includes a second electrode body winding portion 1114 and a second electrode ear winding portion 1122.

[0270] In some embodiments, the housing 20 includes a weak portion 62 surrounding the periphery of the pressure relief portion 61, at least a portion of which is configured to disconnect upon pressure relief to open the pressure relief portion 61.

[0271] The weak point 62 is a relatively weak part of the housing 20, which is a part of the housing 20 that is prone to cracking, breaking, tearing, or opening. For example, the strength of the weak point 62 is less than that of the pressure relief part 61.

[0272] In some examples, this application may create grooves, indentations, or other structures in a predetermined area of ​​the housing 20 to reduce the local strength of the housing 20, thereby forming a weak portion 62 on the housing 20. For example, a thinning process may be performed on a predetermined area of ​​the housing 20, and the thinned portion of the housing 20 forms the weak portion 62. In other examples, a material treatment may be performed on a predetermined area of ​​the housing 20 so that the strength of that area is weaker than the strength of other areas; in other words, that area is the weak portion 62.

[0273] In some examples, the weak portion 62 may surround the pressure relief portion 61. In the event of thermal runaway of the cylindrical battery cell 7, the weak portion 62 is at least partially disconnected; for example, the weak portion 62 is completely disconnected, and the pressure relief portion 61 detaches from the housing 20, thereby forming an exhaust channel; for example, the weak portion 62 is partially disconnected, and the pressure relief portion 61 flips outward under the internal pressure of the cylindrical battery cell 7 to form an exhaust channel.

[0274] In other examples, the weak portion 62 may also partially surround the pressure relief portion 61. The line connecting the two ends of the weak portion 62 and the weak portion 62 together define the pressure relief portion 61. In the event of thermal runaway of the cylindrical battery cell 7, the weak portion 62 breaks, and the pressure relief portion 61 can be rotated outward about the line connecting the two ends of the weak portion 62 as the axis under the action of the internal pressure of the cylindrical battery cell 7 to form a pressure relief channel. Optionally, with the center of the pressure relief portion 61 as the center, the circumferential angle between the weak portion 62 and the center is 180°-350°, optionally 270°-330°.

[0275] As an example, after the weak part 62 is disconnected, the pressure relief part 61 separates from the outer casing, thereby forming an exhaust channel.

[0276] In some embodiments, the housing 20 is provided with a first recess 63, which is recessed relative to the surface of the pressure relief portion 61; the first recess 63 is correspondingly provided with the weak portion 62. By providing the first recess 63, the thickness of the weak portion 62 can be reduced, thereby reducing the strength of the weak portion 62.

[0277] In some embodiments, the housing 20 includes a pressure relief mechanism 60, which is fixedly connected to the second end wall 20a. The pressure relief mechanism 60 includes a first recess 63 and a pressure relief portion 61 located within the area enclosed by the first recess 63. A weak portion 62 is provided at the bottom of the first recess 63, and the pressure relief portion 61 is connected to the weak portion 62. At least a portion of the weak portion 62 is configured to disconnect upon pressure relief to open the pressure relief portion 61.

[0278] Optionally, the second end wall 20a is provided with a pressure relief through hole, and the pressure relief mechanism 60 is connected to the second end wall 20a and covers the pressure relief through hole.

[0279] Optionally, the pressure relief mechanism 60 also includes a connecting portion disposed around the weak portion 62, which is fixedly connected to the second end wall 20a, for example by welding.

[0280] In other embodiments, the second end wall 20a includes a first recess 63 and a pressure relief portion 61 located within the area enclosed by the first recess 63. A weak portion 62 is provided at the bottom of the first recess 63, and the pressure relief portion 61 is connected to the weak portion 62. At least a portion of the weak portion 62 is configured to disconnect upon pressure relief to open the pressure relief portion 61. The pressure relief portion 61 may be part of the second end wall 20a. The weak portion 62 and the pressure relief portion 61 together constitute the pressure relief mechanism 60.

[0281] In some embodiments, at least one electrode 11 has a winding start end E1 and a winding end end E2 at its two ends along the winding direction V. In the radial direction R of the electrode assembly 10, the winding start end E1 is closer to the central axis P5 of the cylindrical battery cell 7 than the winding end E2.

[0282] In some embodiments, the winding end E2 is located outside the winding start end E1 in the radial direction R of the electrode assembly 10. The winding end E2 and the winding start end E1 may be opposite each other in the radial direction R of the electrode assembly 10, or they may not be opposite each other in the radial direction R of the electrode assembly 10.

[0283] In some embodiments, the winding start end E1 is formed in the first electrode winding portion 13.

[0284] In some examples, a portion of the winding start end E1 is located in the first electrode ear winding portion 1121, and a portion of the winding start end E1 is located in the first electrode body winding portion 1113.

[0285] After the electrode 11 is flattened, the length of the first electrode ear winding portion 1121 is equal to the length of the first electrode body winding portion 1113, and the two ends of the first electrode ear winding portion 1121 along the length direction are flush with the two ends of the first electrode body winding portion 1113 along the length direction.

[0286] In other examples, the winding start end E1 is located entirely within the first electrode body winding portion 1113, and in the winding direction V, the first electrode ear winding portion 1121 is spaced a certain distance from the winding start end E1.

[0287] After the electrode 11 is flattened, the length of the first electrode ear winding portion 1121 is less than the length of the first electrode body winding portion 1113. The end of the first electrode ear winding portion 1121 near the second electrode ear winding portion 1122 is flush with the end of the first electrode body winding portion 1113 near the second electrode body winding portion 1114.

[0288] In some embodiments, the winding end E2 is located at the second electrode winding portion 14.

[0289] In some examples, a portion of the winding end E2 is located in the second electrode ear winding portion 1122, and a portion of the winding end E2 is located in the second electrode body winding portion 1114.

[0290] After the electrode 11 is flattened, the length of the second electrode ear winding portion 1122 is equal to the length of the second electrode body winding portion 1114, and the two ends of the second electrode ear winding portion 1122 along the length direction are flush with the two ends of the second electrode body winding portion 1114 along the length direction.

[0291] In other examples, the winding end E2 is located entirely within the winding portion 1114 of the second electrode body, and the winding portion 1122 of the second electrode ear is spaced a certain distance from the winding end E2 in the winding direction V.

[0292] After the electrode 11 is flattened, the length of the second electrode ear winding portion 1122 is less than the length of the second electrode body winding portion 1114. The end of the second electrode ear winding portion 1122 near the first electrode ear winding portion 1121 is flush with the end of the second electrode body winding portion 1114 near the first electrode body winding portion 1113.

[0293] In some embodiments, the first electrode winding portion 1121 is provided with a winding start end E1, and the second electrode winding portion 1122 is provided with a winding end end E2.

[0294] In some embodiments, the portion of the first tab winding portion 1121 near the winding start end E1 is provided with a first notch G1; the first notch G1 penetrates the winding start end E1 along the winding direction V and penetrates the end face of the tab 112 away from the electrode body 111 along the axial direction Z.

[0295] As an example, after the electrode 11 is flattened, the first notch G1 can be rectangular, triangular, trapezoidal or other shapes.

[0296] In this embodiment, by providing the first notch G1, the mutual binding effect between the multi-layer structures of the first electrode winding portion 1121 can be weakened. During thermal runaway of the cylindrical battery cell 7, the binding effect between the multi-layer structures of the first electrode winding portion 1121 is easily broken under air pressure, thereby allowing at least a portion of the first electrode winding portion 13 to be easily discharged through the exhaust channel under air pressure, increasing the exhaust rate, reducing the risk of explosion of the cylindrical battery cell 7, and improving the reliability of the cylindrical battery cell 7.

[0297] In some embodiments, the first notch G1 is located on the radial side R of the electrode assembly 10, near the central axis P5 of the cylindrical battery cell 7 on the side of the first weld portion W1. This embodiment of the application can reduce the risk of welding to the first notch G1 during the welding process of the current collector 40 and the tab 112, thereby reducing the risk of incomplete welds and improving the welding strength of the current collector 40 and the tab 112.

[0298] In some embodiments, the first electrode lug winding portion 1121 includes a first loop portion 11211. In the axial direction Z, the second electrode lug winding portion 1122 extends beyond the first loop portion 11211 in a direction away from the electrode body 111.

[0299] In the winding direction V, the first loop 11211 can be a continuous structure or a discontinuous structure.

[0300] After the electrode 11 is flattened, in the width direction Y of the electrode 11, the second electrode lug winding portion 1122 extends beyond the first coil portion 11211 in a direction away from the electrode body 111. The width direction of the electrode 11 in the flattened state is parallel to the axial direction Z of the electrode 11 in the winding state.

[0301] In this embodiment, by reducing the dimension of the first loop portion 11211 along the Z-axis, the mutual binding effect between the first electrode lug winding portion 1121 and the second electrode lug winding portion 1122 can be weakened. When the cylindrical battery cell 7 experiences thermal runaway, the mutual binding effect between the first electrode lug winding portion 1121 and the second electrode lug winding portion 1122 is easily broken under air pressure. This allows the portion of the first electrode winding portion 13 corresponding to the first loop portion 11211 to be easily discharged through the exhaust channel under air pressure, increasing the exhaust rate, reducing the risk of explosion of the cylindrical battery cell 7, and improving the reliability of the cylindrical battery cell 7.

[0302] In some embodiments, the first electrode lug winding portion 1121 includes a second coil portion 11212 located outside the first coil portion 11211, and the second coil portion 11212 is connected to the second electrode lug winding portion 1122. In the axial direction Z, the second coil portion 11212 extends beyond the first coil portion 11211 in a direction away from the electrode body 111.

[0303] In the winding direction V, the second coil portion 11212 can be a continuous structure or a discontinuous structure. The end of the first coil portion 11211 near the second coil portion 11212 along the winding direction V can be connected to the second coil portion 11212.

[0304] After the electrode 11 is flattened, in the width direction Y of the electrode 11, the second coil portion 11212 extends beyond the first coil portion 11211 in a direction away from the electrode body 111. The width direction of the electrode 11 in the flattened state is parallel to the axial direction Z of the electrode 11 in the wound state.

[0305] In the winding direction V, the length of the first coil 11211 can be greater than, equal to or less than the length of the second coil 11212.

[0306] In this embodiment, by reducing the dimension of the first coil 11211 along the axial direction Z, the mutual binding effect between the first coil 11211 and the second coil 11212 can be weakened. When the cylindrical battery cell 7 experiences thermal runaway, the mutual binding effect between the first coil 11211 and the second coil 11212 is easily broken under air pressure. This allows the portion of the first electrode winding portion 13 corresponding to the first coil 11211 to be easily discharged through the exhaust channel under air pressure, increasing the exhaust rate, reducing the risk of explosion of the cylindrical battery cell 7, and improving the reliability of the cylindrical battery cell 7. The second coil 11212 extends beyond the first coil 11211 in the axial direction Z, and it can support the current collector 40. Therefore, when welding the current collector 40 and the second electrode ear winding portion 1122, the stability of the current collector 40 is improved, the risk of incomplete welding is reduced, and the welding strength is increased.

[0307] In some embodiments, the first ring portion 11211 is spaced apart from the current collecting member 40 in the axial direction Z.

[0308] In some embodiments, the first loop portion 11211 is provided with a winding start end E1.

[0309] In some embodiments, in the axial direction Z, the first notch G1 is provided on the side of the first ring portion 11211 away from the electrode body 111.

[0310] For example, after the electrode 11 is flattened, the first notch G1 is located on the side of the first ring portion 11211 away from the electrode body 111 in the width direction Y of the electrode 11.

[0311] By setting the first notch G1, the dimension of the first ring portion 11211 along the axial direction Z can be reduced.

[0312] In some embodiments, the first coil portion 11211 is wound into multiple turns. Exemplarily, the first coil portion 11211 is wound into 2-20 turns along the winding direction V, such as 2 turns, 2.5 turns, 3 turns, 3.5 turns, 4 turns, 4.5 turns, 5 turns, 6 turns, 8 turns, 10 turns, 12 turns, 15 turns, 18 turns, or 20 turns.

[0313] In some embodiments, the cylindrical battery cell 7 includes an electrode terminal 30 disposed on the housing 20, and the electrode terminal 30 is welded to the current collector 40 to form a second welded portion W2. On a projection plane perpendicular to the axial direction Z, the orthographic projection of the second welded portion W2 is located outside the orthographic projection of the first ring portion 11211.

[0314] The tab 112 can be electrically connected to the electrode terminal 30 through the current collector 40.

[0315] In this embodiment, the second electrode lug winding portion 1122 extends beyond the first coil portion 11211 in the axial direction Z, and it can support the current collector 40. By providing the second welding portion W2 on the outside of the first coil portion 11211, the welding area of ​​the current collector 40 can be effectively supported during the welding process of the current collector 40 and the electrode terminal 30, reducing the risk of incomplete welding and improving the welding strength.

[0316] The second ring portion 11212 extends beyond the first ring portion 11211 in the axial direction Z, and it can also support the current collection member 40.

[0317] In some embodiments, on a projection plane perpendicular to the Z-axis, the orthographic projection of the second weld portion W2 at least partially overlaps with the orthographic projection of the second ring portion 11212. Optionally, on a projection plane perpendicular to the Z-axis, the orthographic projection of the second weld portion W2 lies within the projection of the second ring portion 11212.

[0318] In some embodiments, on a projection plane perpendicular to the axial direction Z, the orthographic projection of the second weld portion W2 at least partially overlaps with the orthographic projection of the second electrode ear winding portion 1122.

[0319] In some embodiments, on a projection plane perpendicular to the Z-axis, the orthographic projection of the first pole lug winding portion 1121 is located within the orthographic projection of the pressure relief portion 61.

[0320] The embodiments of this application can reduce the obstruction of the pressure relief section 61 to the first electrode winding section 13 when the cylindrical battery cell 7 experiences thermal runaway. This is beneficial to increase the portion of the first electrode winding section 13 discharged through the exhaust channel, improve the exhaust rate, reduce the risk of the cylindrical battery cell 7 exploding, and improve the reliability of the cylindrical battery cell 7.

[0321] In some embodiments, the first electrode winding portion 1121 is provided with a winding start end E1, and the winding start end E1 is disposed opposite to the pressure relief portion 61 along the axial direction Z. In a projection plane perpendicular to the axial direction Z, the orthographic projection of the winding start end E1 is located within the orthographic projection of the pressure relief portion 61.

[0322] When the cylindrical battery cell 7 experiences thermal runaway, the winding start end E1 is easily discharged to the outside of the casing 20 through the exhaust channel under the action of air pressure. This helps to reduce the resistance of the first electrode winding part 13 discharged through the exhaust channel, increase the exhaust rate, reduce the risk of the cylindrical battery cell 7 exploding, and improve the reliability of the cylindrical battery cell 7.

[0323] In some embodiments, the electrode assembly 10 is provided with a central hole 15, which extends along the axial direction Z.

[0324] For example, the central hole 15 extends through the electrode assembly 10 along the axial direction Z. The electrode assembly 10 has a wound structure, and the central hole 15 is formed at the center of the winding of the electrode assembly 10.

[0325] The central hole 15 can serve as a flow channel for the electrolyte, improving the wetting effect of the electrolyte on the electrode assembly 10. In the event of thermal runaway in the cylindrical battery cell 7, the central hole 15 can serve as a channel for gas discharge, increasing the gas discharge rate and reducing the risk of explosion.

[0326] In some embodiments, the central axis P5 of the cylindrical battery cell 7 passes through the central hole 15.

[0327] In some embodiments, the first electrode loop winding portion 1121 is disposed around the outer periphery of the central hole 15, and in the projection plane perpendicular to the axial direction Z, the orthographic projection of the central hole 15 is located within the orthographic projection of the pressure relief portion 61.

[0328] For example, the first electrode winding portion 13 is disposed around the outer periphery of the central hole 15.

[0329] When thermal runaway occurs in the cylindrical battery cell 7, gas can act on the pressure relief section 61 through the central hole 15, thereby opening the pressure relief section 61 and forming an exhaust channel. The central hole 15 can reduce the risk of gas blockage and the inability of the pressure relief section 61 to open in time. The central hole 15 can not only reduce the binding effect on the winding start end E1 of the first electrode winding section 13, but also guide the gas flow, increase the gas pressure on the first electrode winding section 13, so that at least a part of the first electrode winding section 13 can be easily discharged through the exhaust channel under the action of gas pressure, improve the exhaust rate, reduce the risk of the cylindrical battery cell 7 exploding, and improve the reliability of the cylindrical battery cell 7.

[0330] In some embodiments, the outer diameter of the electrode assembly 10 is D1, the diameter of the central hole 15 is D2, and D2 / D1 ∈ [5%, 25%].

[0331] As an example, D2 / D1 is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 18%, 20%, 21%, 22%, 23%, 24%, or 25%.

[0332] In this embodiment, setting D2 / D1 to greater than or equal to 5% can increase the venting efficiency of the central hole 15, reduce the resistance encountered by the first electrode winding portion 13 during its ejection to the outside of the housing 20, increase the venting rate, reduce the risk of explosion of the cylindrical battery cell 7, and improve the reliability of the cylindrical battery cell 7. Setting D2 / D1 to less than or equal to 25% can reduce the impact of opening the central hole 15 on the energy density of the cylindrical battery cell 7 and reduce the risk of collapse in the middle of the electrode assembly 10.

[0333] In some embodiments, on a projection plane perpendicular to the Z-axis, the orthographic projection of the second pole lug winding portion 1122 at least partially overlaps with the orthographic projection of the pressure relief portion 61.

[0334] In this embodiment of the application, in the axial direction Z, the second electrode ear winding portion 1122 can be located on the side of the electrode body 111 away from the pressure relief portion 61, or it can be located on the side of the electrode body 111 close to the electrode body 111.

[0335] When thermal runaway occurs in the cylindrical battery cell 7, a portion of the electrode 11 corresponding to the second tab winding portion 1122 (e.g., fragments, particles, etc. generated by the reaction of the electrode 11 under high temperature and high pressure) can also be discharged outside the casing 20 through the exhaust channel under the action of gas pressure, thereby increasing the exhaust rate, reducing the risk of the cylindrical battery cell 7 exploding, and improving the reliability of the cylindrical battery cell 7.

[0336] In some embodiments, on a projection plane perpendicular to the Z-axis, the orthographic projection of the second pole piece winding portion 14 at least partially overlaps with the orthographic projection of the pressure relief portion 61.

[0337] In some embodiments, on a projection plane perpendicular to the Z-axis, a portion of the orthographic projection of the second electrode winding portion 14 is located outside the orthographic projection of the pressure relief portion 61. Embodiments of this application can reduce the risk of the electrode 11 as a whole detaching from the exhaust channel.

[0338] In some embodiments, in the winding direction V, the length of the second electrode winding portion 1122 is greater than the length of the first electrode winding portion 1121.

[0339] After the electrode 11 is flattened, the length of the second electrode ear winding portion 1122 is greater than the length of the first electrode ear winding portion 1121.

[0340] The second tab winding portion 1122 has a large length in the winding direction V, which is beneficial to increase the size of the second tab winding portion 1122 in the radial direction R of the electrode assembly 10, that is, to increase the size of the first welding portion W1 in the radial direction R of the electrode assembly 10, thereby increasing the current flow area between the current collector 40 and the tab 112 and improving the current flow capacity of the cylindrical battery cell 7.

[0341] In some embodiments, both electrodes 11 include an electrode body 111 and an electrode tab 112. The electrode tab 112 of one electrode 11 is a first electrode tab 112a, and the electrode tab 112 of the other electrode 11 is a second electrode tab 112b. The first electrode tab 112a and the second electrode tab 112b are respectively disposed at opposite ends of the electrode assembly 10 along the axial direction Z, and both the first electrode tab 112a and the second electrode tab 112b include a first electrode tab winding portion 1121 and a second electrode tab winding portion 1122.

[0342] In the winding direction V, the length of the first electrode winding portion 1121 of the first electrode tab 112a and the length of the first electrode winding portion 1121 of the second electrode tab 112b may be the same or different. Similarly, in the winding direction V, the length of the second electrode winding portion 1122 of the first electrode tab 112a and the length of the second electrode winding portion 1122 of the second electrode tab 112b may be the same or different.

[0343] In some embodiments, in the axial direction Z, both ends of the electrode assembly 10 are provided with current collecting members 40, and the current collecting members 40 at both ends of the electrode assembly 10 are respectively a first current collecting member 40a and a second current collecting member 40b. The first current collecting member 40a is welded to the second electrode lug winding portion 1122 of the first electrode lug 112a, but not to the first electrode lug winding portion 1121 of the first electrode lug 112a; the second current collecting member 40b is welded to the second electrode lug winding portion 1122 of the second electrode lug 112b, but not to the first electrode lug winding portion 1121 of the second electrode lug 112b.

[0344] The first current collector 40a and the second current collector 40b may have the same or different shapes.

[0345] During the thermal runaway of the cylindrical battery cell 7, the first electrode winding portion 13 of both electrodes 11 can be at least partially discharged to the outside of the casing 20 through the exhaust channel, thereby helping to increase the exhaust rate, realize directional pressure relief of the cylindrical battery cell 7, reduce the risk of the cylindrical battery cell 7 exploding, and improve the reliability of the cylindrical battery cell 7.

[0346] In some embodiments, the first tab 112a is cylindrical and the second tab 112b is cylindrical. The outer diameter of the first tab 112a and the outer diameter of the second tab 112b may be the same or different; the inner diameter of the first tab 112a and the inner diameter of the second tab 112b may be the same or different.

[0347] In some embodiments, the first current collector 40a is annular.

[0348] In some embodiments, the second current collector 40b is annular.

[0349] In some embodiments, the housing 20 includes a first end wall 211, a second end wall 20a, and a side wall 212, with the first end wall 211 and the second end wall 20a respectively disposed at both ends of the side wall 212 along the axial direction Z. The cylindrical battery cell 7 includes an electrode terminal 30 disposed on the first end wall 211, a first tab 112a electrically connected to the electrode terminal 30 through a first current collector 40a, and a second tab 112b electrically connected to the first end wall 211 through a second current collector 40b and the side wall 212.

[0350] As an example, one of the electrode terminal 30 and the first end wall 211 serves as the first electrode lead-out portion 7a, and the other serves as the second electrode lead-out portion 7b.

[0351] The electrode terminal 30 and the first end wall 211 can serve as two exposed electrodes of the cylindrical battery cell 7. The electrode terminal 30 and the first end wall 211 are located on the same side, which is beneficial for assembling multiple cylindrical battery cells 7 into a group and simplifies the battery structure.

[0352] In some embodiments, the second end wall 20a is welded to the second current collector 40b, and the second end wall 20a is electrically connected to the side wall 212.

[0353] The second end wall 20a can be directly connected to the side wall 212, or it can be connected to the side wall 212 through other conductive structures.

[0354] The second end wall 20a and the second current collector 40b are arranged along the Z-axis. Welding the second end wall 20a and the second current collector 40b together increases the welding area between the second end wall 20a and the second current collector 40b, thereby improving the current carrying capacity of the cylindrical battery cell 7.

[0355] In some embodiments, the second end wall 20a is welded to the second current collector 40b to form a third welded portion W3.

[0356] In some embodiments, a pressure relief portion 61 is provided on the second end wall 20a.

[0357] In some examples, the second end wall 20a is integrally formed with the pressure relief portion 61, meaning that the pressure relief portion 61 constitutes a part of the second end wall 20a. In other examples, the second end wall 20a and the pressure relief portion 61 are formed independently, and the two can be fixedly connected by welding or other means.

[0358] In this embodiment, the pressure relief part 61 is disposed on the second end wall 20a. When high-temperature gas is discharged, the heat and pressure effects on the first end wall 211 and the electrode terminal 30 are reduced, the deformation of the first end wall 211 is reduced, the risk of the electrode terminal 30 detaching from the first end wall 211 is reduced, and the reliability of the cylindrical battery cell 7 is improved.

[0359] In some embodiments, the first electrode 112a is a positive electrode and the second electrode 112b is a negative electrode.

[0360] In some embodiments, at least one electrode 11 includes a positive electrode 11a, which includes an electrode body 111 and a tab 112. The tab 112 of the positive electrode 11a is not coated with an active material layer 1111.

[0361] In some embodiments, the positive electrode 11a includes an insulating layer 113. In the axial direction Z, at least a portion of the insulating layer 113 is disposed on the end region of the tab 112 near the electrode body 111.

[0362] The area of ​​the tab 112 of the positive electrode 11a that is far from the electrode body 111 is not provided with an insulating layer 113.

[0363] As an example, the insulating layer 113 may be, but is not limited to, an insulating coating, an insulating adhesive (e.g., hot melt adhesive, etc.) or an insulating tape.

[0364] The insulating layer 113 can be integrally disposed on the tab 112 or partially disposed on the tab 112.

[0365] By providing an insulating layer 113 in this embodiment, the risk of burrs on the negative electrode 11b coming into contact with the tab 112 and causing a short circuit can be reduced, thereby improving reliability.

[0366] In some embodiments, the thickness of the insulating layer 113 is less than the thickness of the active material layer 1111.

[0367] In some embodiments, along the winding direction V, the two ends of the insulating layer 113 are flush with the two ends of the active material layer 1111.

[0368] After the electrode 11 is flattened, the length of the insulating layer 113 is equal to the length of the active material layer 1111.

[0369] In some embodiments, in the radial direction R of the electrode assembly 10, the insulating layer 113 separates the tab 112 of the positive electrode 11a from the edge of the tab 112 of the electrode body 111 of the negative electrode 11b away from the negative electrode 11b, in order to reduce the risk of short circuit.

[0370] In some embodiments, in the axial direction Z, a first notch G1 is provided on the side of the insulating layer 113 away from the electrode body 111.

[0371] In some embodiments, the first notch G1 is spaced apart from the insulating layer 113 in the axial direction Z. Embodiments of this application can reduce the risk of cutting into the insulating layer 113 during the process of cutting the tab 112 to form the first notch G1.

[0372] In some embodiments, at least one electrode 11 includes a negative electrode 11b, the negative electrode 11b includes an electrode body 111 and a tab 112, and the tab 112 of the negative electrode 11b is not coated with an active material layer 1111.

[0373] In some embodiments, along the axial direction Z, both ends of the active material layer 1111 of the negative electrode 11b extend beyond the active material layer 1111 of the positive electrode 11a.

[0374] The edge of the tab 112 of the current collector 1112 of the negative electrode 11b, which is away from the negative electrode 11b, is opposite to the tab 112 of the positive electrode 11a in the radial direction R of the electrode assembly 10. The insulating layer 113 can separate the edge of the tab 112 of the current collector 1112 of the negative electrode 11b, which is away from the negative electrode 11b, from the tab 112 of the positive electrode 11a, so as to reduce the risk of burrs on the edge of the tab 112 of the current collector 1112 of the negative electrode 11b coming into contact with the tab 112 of the positive electrode 11a and causing a short circuit.

[0375] In some embodiments, the tab 112 of the negative electrode 11b is provided with a first notch G1. In the axial direction Z, the first notch G1 is spaced apart from the active material layer 1111 of the negative electrode 11b.

[0376] In some embodiments, at least one electrode 11 has a winding start end E1 and a winding end end E2 at both ends along the winding direction V of the electrode assembly 10, respectively. A first electrode ear winding portion 1121 is provided with a winding start end E1, and a second electrode ear winding portion 1122 is provided with a winding end end E2. In the radial direction R of the electrode assembly, the winding start end E1 is closer to the central axis P5 of the cylindrical battery cell than the winding end E2.

[0377] The second tab winding portion 1122 near the winding end E2 is provided with a second notch G2. The second notch G2 penetrates the winding end E2 along the winding direction V and penetrates the end face of the tab 112 away from the electrode body 111 along the axial direction Z.

[0378] As an example, after the electrode 11 is flattened, the second notch G2 can be rectangular, triangular, trapezoidal or other shapes.

[0379] In this embodiment of the application, by providing the second notch G2, the risk of the winding end E2 of the second electrode winding portion 1122 coming into contact with other components due to tilting can be reduced, thereby reducing the risk of short circuit and improving the reliability of the cylindrical battery cell 7.

[0380] In some embodiments, the cylindrical battery cell 7 further includes an insulating adhesive (not shown) that surrounds the tab 112 from the outer periphery to close the tab 112 and reduce the risk of the tab 112 spreading out. Optionally, the insulating adhesive may be insulating tape.

[0381] In some embodiments, one end of the insulating adhesive along the Z-axis is bonded to the separator, and the other end of the insulating adhesive along the Z-axis is folded over to the side of the tab 112 facing away from the electrode body 111 and bonded to the tab 112. Optionally, the insulating adhesive is also bonded to the outer periphery of the current collector 40.

[0382] In this embodiment of the application, by providing the second notch G2, the risk of the winding end E2 of the second electrode ear winding portion 1122 puncturing the insulating adhesive can be reduced, thereby reducing the risk of the winding end E2 of the second electrode ear winding portion 1122 contacting the outer shell 20 and short-circuiting.

[0383] In some embodiments, the tab 112 of the positive electrode 11a is provided with a second notch G2. Optionally, in the axial direction Z, the second notch G2 is provided on the side of the insulating layer 113 facing away from the electrode body 111.

[0384] In some embodiments, the tab 112 of the negative electrode 11b is provided with a second notch G2. In the axial direction Z, the second notch G2 is spaced apart from the active material layer 1111 of the negative electrode 11b.

[0385] In some embodiments, the second notch G2 is located on the outer side of the first weld portion W1 in the radial direction R of the electrode assembly 10.

[0386] In some embodiments, in the radial direction R of the electrode assembly 10, the first weld portion W1 is closer to the central axis P5 of the cylindrical battery cell relative to the second notch G2.

[0387] For example, in a projection plane perpendicular to the axial direction Z, along the radial direction R of the electrode assembly 10, the orthographic projection of the second notch G2 is located outside the orthographic projection of the first weld portion W1.

[0388] The embodiments of this application can reduce the risk of welding to the second notch G2 during the welding process of the current collector 40 and the tab 112, thereby reducing the risk of incomplete welding and improving the welding strength between the current collector 40 and the tab 112.

[0389] In some embodiments, the collector 40 is provided with an exhaust port 41 extending along the axial direction Z. The exhaust port 41 extends through the collector 40 along the axial direction Z.

[0390] In some embodiments, on a projection plane perpendicular to the axial direction Z, the orthographic projection of the exhaust port 41 is located within the orthographic projection of the pressure relief portion 61, and the orthographic projection of the exhaust port 41 at least partially overlaps with the orthographic projection of the first pole lug winding portion 1121.

[0391] During the thermal runaway of the cylindrical battery cell 7, at least a portion of the first electrode winding portion 13 can be released to the outside of the housing 20 under the action of air pressure through the exhaust port 41 and the exhaust channel.

[0392] In some embodiments, in the axial direction Z, the exhaust port 41 of the second collector member 40b is disposed between the pressure relief portion 61 and the first electrode winding portion 1121 of the second electrode ear 112b.

[0393] In some embodiments, the electrode assembly 10 has a central hole 15 extending along the axial direction Z, a first electrode lug winding portion 1121 is disposed around the outer periphery of the central hole 15, and an exhaust passage 41 is opposite to and communicates with the central hole 15 along the axial direction Z.

[0394] On the projection plane perpendicular to the Z-axis, the orthographic projection of the central hole 15 is located within the orthographic projection of the pressure relief part 61, and the orthographic projection of the exhaust port 41 at least partially overlaps with the orthographic projection of the central hole 15.

[0395] When thermal runaway occurs in the cylindrical battery cell 7, gas can act on the pressure relief section 61 through the central hole 15 and the vent hole 41, thereby opening the pressure relief section 61 and forming an exhaust channel. At least a portion of the first electrode winding section 13 can easily be discharged to the outside of the conductive shell 20 under the action of gas pressure through the vent hole 41 and the exhaust channel, increasing the exhaust rate, reducing the risk of explosion of the cylindrical battery cell 7, and improving the reliability of the cylindrical battery cell 7.

[0396] In some embodiments, the exhaust port 41 of the first collector 40a and the exhaust port 41 of the second collector 40b are respectively disposed on both sides of the central hole 15 along the axial direction Z.

[0397] In some embodiments, both electrodes 11 include a first electrode winding portion 13. A gap G3 is provided between the electrode bodies 111 of the two first electrode winding portions 13.

[0398] As an example, the gap G3 can be the space located between the electrode bodies 111 of the two electrodes 11 that is not filled by the separator 12.

[0399] As an example, the gap G3 can be formed in a variety of ways. For instance, when winding the positive electrode 11a, the separator 12, and the negative electrode 11b, the tightness of the electrode assembly 10 after winding can be adjusted by controlling the tension or other parameters of the three components, thereby forming a gap G3 of a predetermined size.

[0400] For example, a gap G3 is formed between the electrode bodies 111 of the two electrodes by creating a recess on the surface of the electrode body 111. Optionally, the recess extends along the axial direction Z.

[0401] For example, a gap G3 is formed between the electrode bodies 111 of the two electrodes 11 by providing a protruding structure on the surface of one of the electrode bodies 111 and the spacer 12.

[0402] In this embodiment, by setting a gap G3, the pressure between the electrode bodies 111 of the two electrode sheets 11 can be reduced, and the binding effect of the electrode bodies 111 of the two electrode sheets 11 on each other can be weakened. When thermal runaway occurs in the cylindrical battery cell 7, the two first electrode winding portions 13 can easily separate under the action of air pressure and be discharged to the outside of the casing 20 at least partially through the exhaust channel, thereby increasing the exhaust rate, reducing the risk of explosion of the cylindrical battery cell 7, and improving the reliability of the cylindrical battery cell 7.

[0403] During the cycling process of the cylindrical battery cell 7, the gap G3 provides space for the expansion of the active material layer 1111, reducing the pressure between the electrode bodies 111 of the two electrodes 11. This reduces the compression of the electrolyte within the internal pores of the active material layer 1111, decreasing the concentration difference of the electrolyte in different regions within the electrode 11 and improving the cycling performance of the cylindrical battery cell 7 with its larger diameter. The gap G3 also reduces the expansion of the electrode assembly 10, thereby reducing the compression effect on the casing 20, lowering the risk of deformation and cracking of the casing 20, and improving the reliability of the cylindrical battery cell 7. By setting the gap G3, the increase in expansion force caused by increasing the diameter of the cylindrical battery cell 7 can be reduced, thus increasing the capacity of the cylindrical battery cell 7.

[0404] The gap G3 can also accommodate electrolyte to improve the wetting effect of the electrolyte on the positive electrode 11a and the negative electrode 11b, thereby improving the cycle performance of the cylindrical battery cell 7.

[0405] In addition, when ion deposition problems occur in the negative electrode 11b during cycling, such as lithium deposition, the gap G3 can provide space for the deformation of the separator 12, so that the separator 12 can release the pressure exerted on it by the lithium dendrites through deformation, thereby avoiding the separator 12 from being punctured to a certain extent, reducing the risk of short circuit and improving reliability.

[0406] In some embodiments, at least a portion of the gap G3 has a radial dimension D3 of 5 μm-60 μm.

[0407] As an example, the radial dimension D3 of the gap G3 can be the dimension of the gap G3 along the radial direction R of the electrode assembly 10. The radial dimension of the gap G3 can be the same or different at different locations.

[0408] Optionally, the radial dimension D3 of each part of the gap G3 is 5μm-60μm.

[0409] Optionally, the radial dimension D3 of the gap G3 can be 5μm, 6μm, 8μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm or a range of any two of the above values.

[0410] As an example, the radial dimension of the gap G3 can be measured as follows:

[0411] Discharge the cylindrical battery cell to the lower cutoff voltage (e.g., 2.5V);

[0412] Using CT (Computed Tomography) technology, X-rays are used to obtain cross-sectional images of cylindrical battery cells. The cross-section is perpendicular to the central axis of the cylindrical battery cell and shows the electrode body of the positive electrode, the electrode body of the negative electrode, and the separator.

[0413] Based on this image, a virtual straight line is defined, which can pass through the center of the cross section (the virtual straight line intersects the central axis of the cylindrical battery cell);

[0414] Based on the image and the virtual line, along a direction away from the center of the cross-section and parallel to the virtual line, select the electrode body of five adjacent positive electrode sheets. For these five positive electrode sheet bodies, obtain the first intersection point between the outer surface of the electrode body of the first (innermost) positive electrode sheet and the virtual line, obtain the second intersection point between the inner surface of the electrode body of the fifth positive electrode sheet and the virtual line, and measure the distance S between the first and second intersection points. Among them, these five positive electrode sheet bodies belong to the first electrode winding part of the positive electrode sheet.

[0415] Disassemble the cylindrical battery cell and unfold the positive electrode, negative electrode, and separator;

[0416] 50 positions are randomly selected on the main body of the positive electrode sheet, and 50 thickness values ​​are measured. Then the average value of the 50 thickness values ​​is calculated. This average value can be the thickness T1 of the main body of the positive electrode sheet.

[0417] Arbitrarily select 50 positions on the electrode body of the negative electrode sheet, measure 50 thickness values, and then calculate the average value of the 50 thickness values. This average value can be the thickness T2 of the electrode body of the negative electrode sheet.

[0418] Select 50 arbitrary locations on the separator and measure 50 thickness values. Then calculate the average value of the 50 thickness values, which can be the thickness T3 of the separator.

[0419] The outer surface of the positive electrode body of the first layer and the inner surface of the positive electrode body of the fifth layer are provided with three layers of positive electrode bodies, four layers of negative electrode bodies, and eight layers of separators; the outer surface of the positive electrode body of the first layer and the inner surface of the positive electrode body of the fifth layer form eight gaps. Radial dimension D3 = (S - 3 × T1 - 4 × T2 - 8 × T3) / 8.

[0420] In this embodiment, the radial dimension D3 of the gap G3 is limited to be greater than or equal to 5 μm. This reduces the pressure between the electrode bodies 111 of the two electrodes 11 and weakens the binding effect of the electrode bodies 111 on each other, making it easier for the two first electrode winding portions 13 to be discharged to the outside of the casing 20 under the action of air pressure. In this embodiment, the radial dimension D3 of the gap G3 is limited to be less than or equal to 60 μm. This shortens the ion migration path between the active material layer 1111 of the positive electrode 11a and the active material layer 1111 of the negative electrode 11b, reduces the internal resistance of the cylindrical battery cell 7, reduces heat generation, and reduces the impact of the gap G3 on the energy density.

[0421] Limiting the radial dimension D3 of the gap G3 to greater than or equal to 5 μm can also provide space for the expansion of the active material layer 1111 of the negative electrode 11b, reduce the expansion force, improve the cycle performance of the cylindrical battery cell 7, and reduce the risk of deformation and cracking of the casing 20.

[0422] In some embodiments, the gap G3 includes a first gap and a second gap, the first gap being formed between the electrode body 111 of the positive electrode 11a and the separator 12, and the second gap being formed between the electrode body 111 of the negative electrode 11b and the separator 12.

[0423] As an example, the radial dimension of the first gap is D31, and the radial dimension of the second gap is D32. The radial dimension of gap G3 is D3 = D31 + D32.

[0424] In some embodiments, gaps G3 are provided on both the inner and outer sides of the electrode body 111 of the positive electrode 11a.

[0425] In some embodiments, a gap G3 is provided between the electrode bodies 111 of the two electrode sheets 11. A portion of the gap G3 is disposed between the electrode bodies 111 of the two first electrode winding portions 13, and another portion of the gap G3 is disposed between the electrode bodies 111 of the two second electrode winding portions 14.

[0426] In some embodiments, at least one electrode 11 includes a positive electrode 11a, which includes an electrode body 111 and a tab 112. The active material layer 1111 of the positive electrode 11a includes a positive active material, which includes a layered transition metal oxide.

[0427] Layered transition metal oxides include those 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.

[0428] For example, b is 0.8, 0.82, 0.84, 0.85, 0.88, 0.9, 0.92, 0.94, or 0.95.

[0429] 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.

[0430] Cylindrical battery cells with high nickel content have advantages such as high energy density, good low-temperature performance, and good charge and discharge performance.

[0431] Specifically, the active material layer 1111 of the positive electrode 11a 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 levels, 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, allowing electrical equipment to operate normally in low-temperature environments.

[0432] However, cylindrical battery cells 7 with high nickel content have relatively poor thermal stability, and generate more heat and gas during thermal runaway. At least a portion of the first electrode winding portion 13 can be released to the outside of the casing 20 through the exhaust channel under the action of gas pressure, thereby increasing the exhaust rate. The embodiments of this application can quickly release the high-temperature gas generated by the nickel cylindrical battery cell 7 during thermal runaway, thereby reducing the risk of explosion and improving the energy density and reliability of the cylindrical battery cell 7.

[0433] In this embodiment, b is set to less than or equal to 0.95, which can reduce the risk of explosion when the cylindrical battery cell 7 experiences thermal runaway.

[0434] 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.

[0435] 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.

[0436] 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.

[0437] Chain-like ester solvents face the problem of decomposition and gas generation at high temperatures. In the event of thermal runaway of a cylindrical battery, at least a portion of the first electrode winding portion 13 can be released to the outside of the casing 20, thereby promptly releasing the gas generated by the decomposition of the chain-like ester solvent and reducing the risk of explosion.

[0438] In this embodiment, the mass percentage of the chain ester solvent is set to be less than or equal to 76.5 wt%, which can limit the decomposition and gas generation of the cylindrical battery cell 7 during normal charge and discharge cycles. This reduces the impact of the chain ester solvent on the internal pressure of the casing 20, reduces the deformation of the casing 20, lowers the risk of failure of the cylindrical battery cell 7, and improves reliability.

[0439] 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.

[0440] In some embodiments, the chain ester solvent includes at least one of chain carbonates and chain carboxylic esters.

[0441] 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 cylindrical battery cell 7.

[0442] In some embodiments, the height of the housing 20 is 50 mm to 150 mm. For example, the height of the housing 20 is 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, or 150 mm.

[0443] The height of the outer casing 20 can be the dimension of the outer casing 20 along the axial direction Z.

[0444] Optionally, the height of the housing 20 is 60mm-100mm.

[0445] Setting the height of the outer casing 20 to be greater than or equal to 50 mm can increase the capacity and energy density of the cylindrical battery cell 7. In the event of thermal runaway of the cylindrical battery, at least a portion of the first electrode winding portion 13 can be discharged to the outside of the outer casing 20, thereby reducing the impact of increasing the height of the outer casing 20 on the exhaust rate. Setting the height of the cylindrical battery cell 7 to be less than or equal to 150 mm reduces the risk of explosion of the cylindrical battery cell 7.

[0446] In some embodiments, the diameter of the housing 20 is 35 mm to 80 mm. As an example, the diameter of the housing 20 may be 35 mm, 38 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm or 80 mm.

[0447] Setting the diameter of the outer casing 20 to be greater than or equal to 35 mm can increase the capacity and energy density of the cylindrical battery cell 7. In the embodiment of this application, at least a portion of the first electrode winding portion 13 can be discharged to the outside of the outer casing 20 in the event of thermal runaway of the cylindrical battery, thereby reducing the impact of increasing the diameter of the outer casing 20 on the exhaust rate.

[0448] The diameter of the cylindrical battery cell 7 is set to be less than or equal to 80 mm to limit the amount of gas generated by the cylindrical battery cell 7 during thermal runaway and reduce the risk of explosion.

[0449] 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.

[0450] Optionally, the height of the outer casing 20 is 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, 3.0 times, 3.1 times, 3.2 times, 3.3 times, 3.4 times, 3.5 times, 3.6 times, 3.7 times, 3.8 times, 3.9 times, or 4.0 times the diameter of the outer casing 20.

[0451] When the housing 20 meets the above-mentioned size requirements, the structural stability of the housing 20 is high, which can improve the reliability of the cylindrical battery cell 7.

[0452] In some embodiments, the height of the housing 20 is 1.5 to 2.5 times the diameter of the housing 20.

[0453] In some embodiments, the sidewall 212 is made of steel.

[0454] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1.5 mm.

[0455] 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, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, or 1.5mm.

[0456] In the embodiments of this application, the thickness of the sidewall 212 has a meaning known in the art and can be detected using equipment and methods known in the art, such as a micrometer or vernier caliper.

[0457] As an example, the material of sidewall 212 includes stainless steel.

[0458] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1.2 mm.

[0459] 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.

[0460] In some embodiments, the material of the first end wall 211 is the same as the material of the side wall 212.

[0461] In some embodiments, the end cap 22 is made of steel.

[0462] In some embodiments, the second loop portion 11212 and the second electrode ear winding portion 1122 are wound together to form a plurality of winding loops C1.

[0463] For example, each winding C1 is wound along the winding direction V. In the winding direction V, the winding C1 can be a continuous structure or an intermittent structure.

[0464] As an example, the multiple winding loops C1 can begin at the end of the second loop 11212 closest to the first loop 11211 along the winding direction V. Along the winding direction V, the winding loop C1 closest to the first loop 11211 can be the first winding loop C1, and the winding loop C1 furthest from the first loop 11211 can be the last winding loop C1. The last winding loop C1 can be a full loop or not; for example, the last winding loop C1 can be 1 / 4 loop, 1 / 2 loop, or 3 / 4 loop.

[0465] In some embodiments, at least one winding C1 is bent at the end away from the electrode body 111.

[0466] The end of the winding C1 that is away from the electrode body 111 can be bent once or multiple times.

[0467] As an example, in the radial direction R of the electrode assembly 10, the end of the winding C1 that is away from the electrode body 111 along the axial direction Z can be bent toward the first winding portion 11211 or be bent away from the first winding portion 11211.

[0468] In some embodiments, at least two windings C1 are bent at the ends away from the electrode body 111.

[0469] In some embodiments, the end of each winding C1 away from the electrode body 111 is bent.

[0470] In some embodiments, at least one winding C1 is bent along the radial direction R of the electrode assembly 10, away from the end of the electrode body 111 in the axial direction Z, toward the direction close to the first winding portion 11211.

[0471] The bent winding ring C1 can block the interlayer gap of the tab 112 after winding, making the end of the tab 112 away from the electrode body 111 more compact, improving the welding strength between the tab 112 and the current collector 40, and reducing the risk of poor welding.

[0472] In one embodiment, a plurality of winding coils C1 are arranged consecutively in the winding direction V.

[0473] Figure 16 is a partial schematic diagram of the electrode assembly and current collector of a cylindrical battery cell provided in some other embodiments of this application.

[0474] Referring to FIG16, in some embodiments, at least one winding C1 is bent along the radial direction R of the electrode assembly 10, away from the end of the electrode body 111 in the axial direction Z, in a direction away from the first winding portion 11211.

[0475] The bent winding ring C1 can block the interlayer gap of the tab 112 after winding, making the end of the tab 112 away from the electrode body 111 more compact, improving the welding strength between the tab 112 and the current collector 40, and reducing the risk of poor welding.

[0476] In some embodiments, at least one winding C1 is alternately bent along the radial direction R of the electrode assembly 10, with the end of the winding away from the electrode body 111 along the axial direction Z, in a direction close to the first winding portion 11211 and in a direction away from the first winding portion 11211.

[0477] By bending the winding coil C1 multiple times, the number of layers of the tab 112 stacked in the axial Z direction can be increased, the density of the end of the tab 112 facing the current collector 40 can be improved, the risk of poor welding can be reduced, and the welding strength between the current collector 40 and the tab 112 can be improved.

[0478] In some embodiments, after the two electrodes 11 and the spacer 12 are wound, the electrode tab 112 can be pressed along the axial direction Z from the side of the electrode tab 112 away from the electrode body 111, so that the end of the electrode tab 112 away from the electrode body 111 is bent and an overlapping area Q is formed.

[0479] Figure 17 is a schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application; Figure 18 is a schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application before the tab is bent; Figure 19 is a schematic diagram of the electrode sheet of a cylindrical battery cell provided in some embodiments of this application in a flattened state; Figure 20 is an enlarged schematic diagram of Figure 19 at the circular frame; Figure 21 is a schematic diagram of the electrode assembly and current collector of a cylindrical battery cell provided in some embodiments of this application after welding; Figure 22 is an enlarged schematic diagram of Figure 21 at the square frame.

[0480] Referring to Figures 17 to 22, in some embodiments, the tab 112 includes a plurality of segments 1123 distributed along the winding direction V, and a cut-off groove 1124 is formed between any two adjacent segments 1123 along the winding direction V.

[0481] For example, after the electrode 11 is flattened, a plurality of segments 1123 are spaced apart along the length direction X of the electrode 11.

[0482] In some examples, all the segments 1123 are formed in the first electrode loop winding portion 1121. In other examples, all the segments 1123 are formed in the second electrode loop winding portion 1122. In still other examples, a portion of the plurality of segments 1123 is formed in the first electrode loop winding portion 1121, and another portion of the plurality of segments 1123 is formed in the second electrode loop winding portion 1122.

[0483] By setting the cut-off groove 1124, the difficulty of bending the tab 112 can be reduced, which is conducive to achieving directional bending of the tab 112.

[0484] By setting the cut-off groove 1124, the obstruction of the electrode tab 112 to the gas can be reduced when the cylindrical battery cell 7 experiences thermal runaway, which is conducive to the gas being discharged from the inside of the electrode assembly 10.

[0485] In some embodiments, at least one segment 1123 is bent.

[0486] In some embodiments, during the process of flattening or smoothing the tab 112, the cutting groove 1124 can reduce the binding force between the segments 1123, which helps to achieve directional bending of the segments 1123.

[0487] In some embodiments, at least a portion of the plurality of segments 1123 are formed in a part of the second ring portion 11212. In a projection plane perpendicular to the axial direction Z, the orthographic projection of the groove bottom surface 11241 of at least one cut-off groove 1124 lies within the orthographic projection of the pressure relief portion 61.

[0488] By providing a cut-off groove 1124 in the second coil 11212, the mutual binding effect between adjacent segments 1123 in the winding direction V of the second coil 11212 is weakened. In the event of thermal runaway in the cylindrical battery cell 7, the second coil 11212 can disperse under air pressure, allowing the portion of the first electrode winding 13 corresponding to the second coil 11212 to be discharged through the exhaust channel under air pressure. This further increases the exhaust rate, reduces the risk of explosion of the cylindrical battery cell 7, and improves the reliability of the cylindrical battery cell 7.

[0489] In some embodiments, at least two segments 1123 are formed in a portion of the second ring portion 11212.

[0490] In some embodiments, in a projection plane perpendicular to the axial direction Z, the orthographic projection of the bottom surface 11241 of at least two cut-off grooves 1124 is located within the orthographic projection of the pressure relief portion 61.

[0491] In some embodiments, the cylindrical battery cell 7 includes an electrode terminal 30 disposed on the housing 20, and the electrode terminal 30 is welded to the current collector 40 to form a second welded portion W2.

[0492] On a projection plane perpendicular to the Z-axis, the two ends of the orthographic projection of the second welded portion W2 have a first projection endpoint E3 and a second projection endpoint E4, respectively. The first projection endpoint E3 is closer to the central axis P5 of the cylindrical battery cell than the second projection endpoint E4. The area between the first arc P1, which passes through the first projection endpoint E3 and surrounds the first ring portion 11211, and the second arc P2, which passes through the second projection endpoint E4 and surrounds the first ring portion 11211, is the first transverse region Q1. At least some of the cut-off grooves 1124 form a first group of cut-off grooves 1124a. In the first group of cut-off grooves 1124a, the orthographic projection of the bottom surface 11241 of all cut-off grooves 1124 is located within the first transverse region Q1.

[0493] The first set of cut-off slots 1124a may include all cut-off slots 1124 or only a portion of the cut-off slots 1124.

[0494] For example, in FIG17, the projection of the first welded portion W1 along the axial direction Z onto the tab 112 and the projection of the second welded portion W2 along the axial direction Z onto the lower tab 112 are shown in cross-section.

[0495] For example, on a projection plane perpendicular to the Z-axis, the orthographic projection of the electrode assembly 10 is circular. The first projection endpoint E3 is the point closest to the center of the electrode assembly 10 in the orthographic projection of the second welding part W2, and the second projection endpoint E4 is the point farthest from the center of the electrode assembly 10 in the orthographic projection of the second welding part W2. On the projection plane perpendicular to the Z-axis, the first arc P1 is a circle passing through the first projection endpoint E3, and the first arc P1 is concentrically arranged with the orthographic projection of the electrode assembly 10. On the projection plane perpendicular to the Z-axis, the second arc P2 is a circle passing through the second projection endpoint E4, and the second arc P2 is concentrically arranged with the orthographic projection of the electrode assembly 10.

[0496] For example, there may be one or more second weld portions W2. For instance, if there are multiple second weld portions W2, then the first projection endpoint E3 is the point closest to the center of the electrode assembly 10 among the orthographic projections of the multiple second weld portions W2.

[0497] For example, on a projection plane perpendicular to the axis Z, the orthographic projection of the second welded part W2 can be a straight line, a curve, or other shapes.

[0498] On a projection plane perpendicular to the Z-axis, the orthographic projection of the second welded part W2 may have one or more first projection endpoints E3. For example, the orthographic projection of the second welded part W2 may have multiple first projection endpoints E3, and the distance between the multiple first projection endpoints E3 and the center of the electrode assembly 10 is the same, and the first arc P1 passes through the multiple first projection endpoints E3.

[0499] On a projection plane perpendicular to the Z-axis, the orthographic projection of the second weld portion W2 may have one or more second projection endpoints E4. For example, the orthographic projection of the second weld portion W2 may have multiple second projection endpoints E4, and the distance between the multiple second projection endpoints E4 and the center of the electrode assembly 10 is the same, with the second arc P2 passing through the multiple second projection endpoints E4.

[0500] For example, the first transverse region Q1 is annular. The first arc P1 and the second arc P2 are concentrically arranged.

[0501] In some embodiments, in the first set of cut-off slots 1124a, the number of turns of a single cut-off slot 1124 is ≤3.

[0502] When welding the electrode terminal 30 and the current collector 40, the portion of the tab 112 corresponding to the first transverse region Q1 can be used to support the area of ​​the current collector 40 that needs to be welded to the electrode terminal 30. In this embodiment, the number of turns of a single cut-off groove 1124 in the first set of cut-off grooves 1124a is set to be less than or equal to 3. This reduces the influence of the cut-off groove 1124 on the strength of the portion of the tab 112 corresponding to the first transverse region Q1, reduces the risk of collapse of the portion of the tab 112 corresponding to the first transverse region Q1, and thus enables the tab 112 to stably support the area of ​​the current collector 40 that needs to be welded to the electrode terminal 30, reduces the risk of incomplete welding, and improves welding strength.

[0503] As an example, in the first set of cut-off slots 1124a, the number of turns of a single cut-off slot 1124 can be 0.5 turns, 1 turn, 1.5 turns, 2 turns, 2.5 turns, or 3 turns.

[0504] In some embodiments, in the first set of cut-off grooves 1124a, the number of cut-off grooves 1124 that are opposite to and connected along the radial direction R of the electrode assembly 10 is ≤3. Embodiments of this application can reduce the impact of the cut-off grooves 1124 on the strength of the portion of the tab 112 corresponding to the first transverse region Q1, reducing the risk of collapse of the portion of the tab 112 corresponding to the first transverse region Q1. This allows the tab 112 to stably support the area of ​​the current collector 40 that needs to be welded to the electrode terminal 30, reducing the risk of incomplete welds and improving weld strength.

[0505] In some embodiments, in the first set of cut-off grooves 1124a, the number of turns of a single cut-off groove 1124 is ≤3, and the number of cut-off grooves 1124 that are opposite to and connected along the radial direction R of the electrode assembly 10 is ≤3.

[0506] In some embodiments, the tab 112 includes a plurality of segments 1123 distributed along the winding direction V, and a cut-off groove 1124 is provided between any two adjacent segments 1123 along the winding direction V. At least a portion of the plurality of segments 1123 is formed in a part of the second tab winding portion 1122. The current collecting member 40 is welded to the segments 1123 of the second tab winding portion 1122 and forms a first welded portion W1. In a projection plane perpendicular to the axial direction Z, the orthographic projection of the groove bottom surface 11241 of at least one cut-off groove 1124 lies within the orthographic projection of the pressure relief portion 61.

[0507] In some examples, all the segments 1123 are formed in the second electrode loop winding portion 1122. In other examples, a portion of the plurality of segments 1123 is formed in the first electrode loop winding portion 1121, and another portion of the plurality of segments 1123 is formed in the second electrode loop winding portion 1122.

[0508] By providing a cutting groove 1124 in the second electrode winding portion 1122, the mutual binding effect between adjacent segments 1123 in the winding direction V of the second electrode winding portion 1122 is weakened. A portion of the electrode 11 corresponding to the second electrode winding portion 1122 (e.g., fragments, particles, etc. generated by the reaction of the electrode 11 under high temperature and high pressure) can also be discharged outside the casing 20 through the cutting groove 1124 and the exhaust channel under the action of gas pressure, thereby increasing the exhaust rate, reducing the risk of explosion of the cylindrical battery cell 7, and improving the reliability of the cylindrical battery cell 7.

[0509] In some embodiments, at least a portion of the interface between the first electrode lug winding portion 1121 and the second electrode lug winding portion 1122 is located on the same segment 1123. This segment 1123 is welded to the current collector member 40. The portion of the segment 1123 located inward along the winding direction V belongs to the first electrode lug winding portion 1121, and the portion of the segment 1123 located outward along the winding direction V belongs to the second electrode lug winding portion 1122.

[0510] In some embodiments, on a projection plane perpendicular to the Z-axis, the two ends of the orthographic projection of the first welded portion W1 have a third projection endpoint E5 and a fourth projection endpoint E6, respectively. The third projection endpoint E5 is closer to the central axis P5 of the cylindrical battery cell than the fourth projection endpoint E6. The area between the third arc P3, which passes through the third projection endpoint E5 and surrounds the first electrode winding portion 1121, and the fourth arc P4, which passes through the fourth projection endpoint E6 and surrounds the first electrode winding portion 1121, is the second transverse region Q2. At least some of the cut-off grooves 1124 form a second set of cut-off grooves 1124b. In the second set of cut-off grooves 1124b, the orthographic projection of the groove bottom surface 11241 of all cut-off grooves 1124 is located within the second transverse region Q2.

[0511] In some examples, the second set of cutoff slots 1124b may include all of the cutoff slots 1124. In other examples, it may include only a portion of the cutoff slots 1124.

[0512] For example, on the projection plane perpendicular to the Z-axis, the orthographic projection of the electrode assembly 10 is a circle. The third projection endpoint E5 is the point closest to the center of the electrode assembly 10 in the orthographic projection of the first welding part W1, and the fourth projection endpoint E6 is the point farthest from the center of the electrode assembly 10 in the orthographic projection of the first welding part W1. On the projection plane perpendicular to the Z-axis, the third arc P3 is a circle passing through the third projection endpoint E5, and the third arc P3 is concentrically arranged with the orthographic projection of the electrode assembly 10. On the projection plane perpendicular to the Z-axis, the fourth arc P4 is a circle passing through the fourth projection endpoint E6, and the fourth arc P4 is concentrically arranged with the orthographic projection of the electrode assembly 10.

[0513] For example, there may be one or more first weld portions W1. For instance, if there are multiple first weld portions W1, then the third projection endpoint E5 is the point closest to the center of the electrode assembly 10 among the orthographic projections of the multiple first weld portions W1.

[0514] For example, on a projection plane perpendicular to the axis Z, the orthographic projection of the first welded part W1 can be a straight line, a curve, or other shapes.

[0515] On a projection plane perpendicular to the Z-axis, the orthographic projection of the first welded part W1 may have one or more third projection endpoints E5. For example, the orthographic projection of the first welded part W1 may have multiple third projection endpoints E5, and the distance between the multiple third projection endpoints E5 and the center of the electrode assembly 10 is the same, and the third arc P3 passes through the multiple third projection endpoints E5.

[0516] On a projection plane perpendicular to the Z-axis, the orthographic projection of the first weld portion W1 may have one or more fourth projection endpoints E6. For example, the orthographic projection of the first weld portion W1 may have multiple fourth projection endpoints E6, and the multiple fourth projection endpoints E6 are equidistant from the center of the electrode assembly 10, with the fourth arc P4 passing through the multiple fourth projection endpoints E6.

[0517] For example, the second transverse region Q2 is annular. The third arc P3 and the fourth arc P4 are concentrically arranged.

[0518] In some examples, on a projection plane perpendicular to the axis Z, the third arc P3 surrounds the orthographic projection of the first ring portion 11211.

[0519] In some embodiments, in the second set of cut-off slots 1124b, the number of turns of a single cut-off slot 1124 is ≤3.

[0520] The portion of the tab 112 corresponding to the second transverse region Q2 is used for welding to the current collecting member 40. In this embodiment, the number of turns of a single cut-off groove 1124 in the second set of cut-off grooves 1124b is set to be less than or equal to 3. This can reduce the impact of opening the cut-off grooves 1124 on the number of overlapping layers of the tab 112 in the axial Z direction, reduce the risk of the tab 112 being welded through, and improve the welding strength.

[0521] In some embodiments, in the second set of cut-off grooves 1124b, the number of cut-off grooves 1124 that are opposite to and connected along the radial direction R of the electrode assembly 10 is ≤3. Embodiments of this application can reduce the impact of opening the cut-off grooves 1124 on the number of overlapping layers of the tabs 112 in the axial direction Z, reduce the risk of the tabs 112 being welded through, and improve the welding strength.

[0522] In some embodiments, in the second set of cut-off grooves 1124b, the number of turns of a single cut-off groove 1124 is ≤3. In the second set of cut-off grooves 1124b, the number of cut-off grooves 1124 that are opposite to and connected along the radial direction R of the electrode assembly 10 is ≤3.

[0523] In some embodiments, among the plurality of segments 1123 of the second electrode winding portion 1122, the segment 1123 furthest from the first electrode winding portion 1121 is wound at least one turn along the winding direction V.

[0524] The segments 1123 furthest from the first tab winding portion 1121 are continuously arranged and wound at least once. They can bind other segments 1123 from the outer periphery, thereby reducing the risk of the tab 112 bulging outward and deforming in the radial direction R of the electrode assembly 10 when the tab 112 is under pressure, and improving the reliability of the cylindrical battery cell 7.

[0525] In some embodiments, the second notch G2 is disposed on the segment 1123 that is furthest from the first tab winding portion 1121 along the winding direction V.

[0526] In some embodiments, at least one electrode 11 includes a positive electrode 11a, which includes an electrode body 111, a tab 112, and an insulating layer 113. The tab 112 of the positive electrode 11a is not coated with an active material layer 1111. In the axial direction Z, at least a portion of the insulating layer 113 is disposed on the end region of the tab 112 near the electrode body 111, and a cut-off piece 1123 is located on the side of the insulating layer 113 facing away from the electrode body 111.

[0527] This embodiment of the application, by providing an insulating layer 113, can reduce the risk of burrs on the negative electrode 11b contacting the tab 112 and causing a short circuit, thereby improving reliability. This embodiment of the application also provides a cut-off piece 1123 on the side of the insulating layer 113 facing away from the electrode body 111, so that during the bending process of the cut-off piece 1123, the stress transmitted to the insulating layer 113 is reduced, thus lowering the risk of the insulating layer 113 detaching.

[0528] In some embodiments, in the axial direction Z, the segment 1123 of the positive electrode 11a is spaced apart from the insulating layer 113.

[0529] In some embodiments, the tab 112 further includes a transition connection portion 1125, and the electrode body 111, the transition connection portion 1125, and the segment 1123 are arranged sequentially along the axial direction Z. The transition connection portion 1125 and two segments 1123 adjacent to each other along the winding direction V form a cutting groove 1124, and the bottom surface 11241 of the cutting groove 1124 is formed on one side edge of the transition connection portion 1125 for connecting the segments 1123.

[0530] For example, the dimension of the transition connection 1125 along the winding direction V is greater than the sum of the dimensions of all the segments 1123 along the winding direction V.

[0531] For example, a portion of the transition connection portion 1125 is formed in the first electrode loop winding portion 1121, and a portion of the transition connection portion 1125 is formed in the second electrode loop winding portion 1122.

[0532] For example, the transition connection portion 1125 extends continuously along the winding direction V.

[0533] In this embodiment, the transition connection 1125 can separate the electrode body 111 from the cut piece 1123, thereby reducing the force transmitted to the electrode body 111 during the bending process of the cut piece 1123, reducing the risk of deformation of the electrode body 111 and the risk of active material falling off in the active material layer 1111.

[0534] In some embodiments, along the direction from the electrode body 111 to the electrode tab 112, the transition connection portion 1125 is used to connect one side edge of the segment 1123 protruding from the separator 12.

[0535] Along the Z-axis, the entire segment 1123 is located outside the spacer 12.

[0536] The embodiments of this application can reduce the risk of the segment 1123 squeezing the isolation member 12 during the bending and deformation process of the segment 1123, reduce the deformation of the isolation member 12, and reduce the risk of short circuit.

[0537] In some embodiments, along the winding direction V, the two ends of the transition connection portion 1125 are flush with the two ends of the electrode body 111. After the electrode 11 is flattened, the length of the transition connection portion 1125 is equal to the length of the electrode body 111.

[0538] In some embodiments, along the winding direction V, the innermost segment 1123 and the transition connection 1125 define a first notch G1 toward the edge of the segment 1123.

[0539] In some embodiments, the positive electrode 11a includes an insulating layer 113, which is disposed on the surface of the transition connection portion 1125.

[0540] In some embodiments, the dimension of one side edge of the piece 1123 used to connect the transition connection portion 1125 in the winding direction V of the electrode assembly 10 is L1, and the sum of the dimensions of the transition connection portion 1125 and the piece 1123 in the axial direction Z is L2, where 0.01≤L2 / L1≤0.3.

[0541] After the electrode 11 is flattened, the sum of the dimension of the transition connection portion 1125 in the width direction Y of the electrode 11 and the dimension of the section 1123 in the width direction Y of the electrode 11 can be L2.

[0542] As an example, L2 / L1 can be 0.01, 0.02, 0.05, 0.08, 0.1, 0.11, 0.12, 0.15, 0.18, 0.2, 0.21, 0.22, 0.25, 0.28 or 0.3.

[0543] In this embodiment, L2 / L1 is limited to less than or equal to 0.3, which can, to a certain extent, balance the space occupied by the tab 112 in the Z-axis and the current carrying capacity of the tab 112. In this embodiment, L2 / L1 is limited to greater than or equal to 0.01 to reduce the bending difficulty of the cut-out piece 1123.

[0544] In some embodiments, the dimension of the transition connection portion 1125 in the axial Z direction is L3, where 0.1mm≤L3≤2mm.

[0545] As an example, L3 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or 2mm.

[0546] In this embodiment, L3 is limited to less than or equal to 2 mm to save space occupied by the transition connection portion 1125 in the axial Z direction and improve the energy density of the cylindrical battery cell 7. In this embodiment, L3 is limited to greater than or equal to 0.1 mm to reduce the force transmitted to the electrode body 111 during the bending process of the cut sheet 1123, thereby reducing the risk of deformation of the electrode body 111 and the risk of active material falling off in the active material layer 1111.

[0547] In some embodiments, the tab 112 is provided with a plurality of cut-off grooves 1124, and the cut-off grooves 1124 and the cut pieces 1123 are arranged alternately along the winding direction V of the electrode assembly 10.

[0548] By setting multiple segments 1123 and multiple cutting grooves 1124, it is beneficial to achieve directional bending of the segments 1123. By setting multiple cutting grooves 1124, the binding effect between the segments 1123 can be reduced. In the event of thermal runaway of the cylindrical battery cell 7, at least some of the multiple segments 1123 can separate under the action of air pressure, so that a portion of the electrode 11 can be discharged through the exhaust channel under the action of air pressure, further increasing the exhaust rate, reducing the risk of explosion of the cylindrical battery cell 7, and improving the reliability of the cylindrical battery cell 7.

[0549] In some embodiments, in the axial direction Z, the size of the slit 1123 along the winding direction V of the electrode assembly 10 tends to decrease in the direction away from the electrode body 111.

[0550] For example, after the electrode 11 is flattened, the size of the cut piece 1123 gradually decreases along the length direction X of the electrode 11 in the direction from the electrode body 111 to the tab 112.

[0551] The embodiments of this application can reduce the difficulty of bending the cut piece 1123.

[0552] In some embodiments, at least one segment 1123 has a bent section 11231 at one end in the Z-axis direction. The bent section 11231 is bent relative to the electrode body 111. The bent section 11231 can be bent once or multiple times.

[0553] In some embodiments, two adjacent segments 1123 in the winding direction V are each provided with a bending segment 11231. The bending directions of the bending segments 11231 of the two adjacent segments 1123 may be the same or different.

[0554] In some examples, the bent segment 11231 of one segment 1123 bends towards the central axis P5 of the cylindrical battery cell 7, while the bent segment 11231 of another adjacent segment 1123 bends away from the central axis P5 of the cylindrical battery cell 7. In other examples, both bent segments 11231 of the two adjacent segments 1123 bend towards the central axis P5 of the cylindrical battery cell 7. In still other examples, both bent segments 11231 of the two adjacent segments 1123 bend away from the central axis P5 of the cylindrical battery cell 7.

[0555] In some embodiments, at least one bent segment 11231 of the segment 1123 includes a first bent portion 11232 that is bent relative to the electrode body 111 toward the central axis P5 of the cylindrical battery cell.

[0556] In some embodiments, the first bend 11232 is bent radially R along the electrode assembly 10.

[0557] In some embodiments, the bent segment 11231 includes a first bent portion 11232.

[0558] In some embodiments, each segment 1123 has a bent section 11231 at one end in the Z-axis direction, which can form an overlapping region Q at the end of the tab 112 away from the electrode body 111. In the overlapping region Q, the bent sections 11231 of at least two segments 1123 overlap in the Z-axis direction. Welding the overlapping region Q to the current collector 40 can reduce the risk of poor soldering and increase the welding area between the tab 112 and the current collector 40, thereby improving the current carrying capacity.

[0559] In some embodiments, each segment 1123 has a first bending portion 11232 on its bending segment 11231. The bending segments 11231 of the multiple segments 1123 are all bent toward the central axis P5 of the cylindrical battery cell 7, which can reduce the bending difficulty and improve the flatness of the overlapping area Q.

[0560] In some other embodiments, at least one of the bent segments 11231 of the segment 112 includes a second bent portion, which is bent relative to the electrode body 111 in a direction away from the central axis P5 of the cylindrical battery cell 7.

[0561] Figure 23 is a partial schematic diagram of the electrode assembly and current collector of a cylindrical battery cell provided in some embodiments of this application after welding.

[0562] Referring to FIG23, in some embodiments, at least one of the bent segments 11231 of the sheet includes at least one second bent portion 11233 which is bent relative to the electrode body 111 in a direction away from the central axis P5 of the cylindrical battery cell.

[0563] In some embodiments, the second bend 11233 is bent radially R along the electrode assembly.

[0564] In some embodiments, at least one segment has a bent section 11231 at one end in the axial direction. The bent section 11231 includes at least one first bent portion 11232 bent relative to the electrode body 111 in a direction close to the central axis P5 of the cylindrical battery cell and at least one second bent portion 11233 bent relative to the electrode body 111 in a direction away from the central axis P5 of the cylindrical battery cell.

[0565] The bend segment 11231 may include one or more first bends 11232. In some examples, the bend segment 11231 may include multiple first bends 11232, with adjacent first bends 11232 connected by second bends 11233.

[0566] The bend segment 11231 may include one or more second bends 11233. In some examples, the bend segment 11231 may include a plurality of second bends 11233, with adjacent second bends 11233 connected by a first bend 11232.

[0567] By bending the segment 1123 multiple times, the number of layers of the segment 1123 stacked in the axial Z direction can be increased, the density of the end region of the tab 112 facing the current collector 40 can be improved, the risk of incomplete welding can be reduced, and the welding strength between the current collector 40 and the tab 112 can be improved.

[0568] In some embodiments, the bending segment 11231 includes a first bending portion 11232 and a second bending portion 11233, both of which are bent along the radial direction R of the electrode assembly 10. The directional bending of the first bending portion 11232 and the second bending portion 11233 is beneficial to improving the density of the end region of the tab 112 toward the current collector 40.

[0569] In some embodiments, the bent segment 11231 includes a first bent portion 11232 and a second bent portion 11233, which are alternately arranged along the axial direction Z. By increasing the number of bends in the bent segment 11231, this embodiment increases the number of layers of the segment 1123 stacked along the axial direction Z, improves the density of the end region of the tab 112 facing the current collector 40, reduces the risk of incomplete soldering, and improves the welding strength between the current collector 40 and the tab 112.

[0570] In some embodiments, after the two electrodes 11 and the spacer 12 are wound, a plurality of segments 1123 of the electrode tab 112 can be pressed along the axial direction Z from the side of the electrode tab 112 away from the electrode body 111, so that the plurality of segments 1123 are bent and form a bent section.

[0571] Figure 24 is a partial cross-sectional view of a cylindrical battery cell provided in some other embodiments of this application; Figure 25 is an enlarged view of Figure 24 at the boxed area; Figure 26 is a schematic diagram of the current collector of a cylindrical battery cell provided in some embodiments of this application.

[0572] Referring to Figures 24 to 26, in some embodiments, the current collector 40 is provided with an exhaust port 41 and a plurality of guide portions 42, the exhaust port 41 extending along the axial direction Z; the plurality of guide portions 42 are spaced apart around the outer periphery of the exhaust port 41. In a projection plane perpendicular to the axial direction Z, the orthographic projection of the exhaust port 41 is located within the orthographic projection of the pressure relief portion 61, and the orthographic projection of the exhaust port 41 at least partially overlaps with the orthographic projection of the first electrode lug winding portion 1121.

[0573] The guide portion 42 is configured to guide the portion of the manifold 40 surrounding the exhaust port 41 to fold outward during depressurization. The outward folding can be a fold towards the side away from the electrode assembly.

[0574] When thermal runaway occurs in the cylindrical battery cell 7, the pressure relief section 61 opens and forms an exhaust channel. Multiple guide sections 42 guide the portion of the current collector 40 surrounding the exhaust hole 41 to fold outward, thereby increasing the exhaust hole 41 on the current collector 40 and reducing the obstruction of the current collector 40 to the first electrode winding section 13. This facilitates at least a portion of the first electrode winding section 13 to be discharged to the outside of the housing 20 through the exhaust hole 41 and the exhaust channel, improving exhaust efficiency and reducing the risk of explosion of the cylindrical battery cell 7.

[0575] In some embodiments, the guide portion 42 extends to the vent hole 41, which helps to reduce the difficulty of the portion of the manifold 40 surrounding the vent hole 41 folding outward during depressurization.

[0576] In other embodiments, the guide portion 42 is spaced apart from the wall of the vent hole 41, and the minimum distance between the guide portion 42 and the wall of the vent hole 41 is less than or equal to 10 mm. The portion of the collector member 40 located between the guide portion 42 and the wall of the vent hole 41 is smaller in size and has lower strength; during pressure relief, the portion of the collector member 40 located between the guide portion 42 and the wall of the vent hole 41 can break under pressure, thereby causing the portion of the collector member 40 surrounding the vent hole 41 to fold outward.

[0577] By spacing the guide portion 42 from the wall of the vent hole 41, the influence of the guide portion 42 on the strength of the current collector 40 can be reduced, thus lowering the risk of the current collector 40 flipping over during normal operation of the battery cell.

[0578] In some embodiments, the plurality of guide portions 42 are arranged radially.

[0579] In some embodiments, guide portions 42 are evenly spaced along the circumference of the current collector 40. In some embodiments, a first welding portion W1 is disposed between two adjacent guide portions 42 in the circumference of the current collector 40. When welding the current collector 40 to the tab 112, the guide portions 42 are avoided to reduce the risk of welding failure.

[0580] In some embodiments, the current collector 40 is welded to the tab 112 to form a plurality of first welded portions W1, which are spaced apart circumferentially along the current collector 40.

[0581] In some embodiments, a plurality of first welded portions W1 and a plurality of guide portions 42 are arranged alternately along the circumference of the flow collector 40.

[0582] In some embodiments, the guide portion 42 extends radially R along the electrode assembly 10.

[0583] In some embodiments, the housing 20 includes a pressure relief portion 61 and a weak portion 62 surrounding the outer periphery of the pressure relief portion 61, at least a portion of the weak portion 62 being configured to disconnect upon pressure relief to open the pressure relief portion 61. On a projection plane perpendicular to the axial direction Z, along the radial direction R of the electrode assembly 10, the orthographic projection of the end of the guide portion 42 away from the exhaust port 41 is located outside the orthographic projection of the weak portion 62 or coincides with the orthographic projection of the weak portion 62.

[0584] After the weak section 62 is disconnected, the pressure relief section 61 opens and forms an exhaust channel. A portion of the current collector 40, guided by the guide section 42, can fold to the outside of the housing 20 via the exhaust channel, thereby increasing the exhaust port 41. In this embodiment, by setting the guide section 42 at a position away from the exhaust port 41, the exhaust port 41 can be maximized. This facilitates at least a portion of the first electrode winding section 13 being discharged to the outside of the housing 20 through the exhaust port 41 and the exhaust channel, improving exhaust efficiency and reducing the risk of explosion of the cylindrical battery cell 7.

[0585] In some embodiments, the guide portion 42 includes a second recess 43, which is recessed relative to one side surface of the manifold 40 along the axial direction Z. By providing the second recess 43, the local thickness of the manifold 40 can be reduced, thereby guiding the portion of the manifold 40 around the exhaust port 41 to fold outward during depressurization.

[0586] In some embodiments, there are multiple second recesses 43. The multiple second recesses 43 are arranged at circumferential intervals along the collecting member 40.

[0587] In other embodiments, the guide portion 42 includes a guide through-hole (not shown) that extends through the flow collector 40. One end of the guide through-hole is connected to the exhaust through-hole 41.

[0588] In some embodiments, the second current collector 40b is provided with a guide portion 42. The first current collector 40a may or may not have a guide portion 42.

[0589] Optionally, the first current collector 40a is not provided with a guide part 42.

[0590] Figure 27 is a schematic diagram of the electrode of a cylindrical battery cell provided in some embodiments of this application after being flattened; Figure 28 is a partial cross-sectional view of Figure 27 along the EE direction.

[0591] Referring to Figures 27 and 28, in some embodiments, the surface of the electrode body 111 is provided with a plurality of electrode recesses 11111. At least a portion of the plurality of electrode recesses 11111 is formed in the first electrode winding portion 13.

[0592] The electrode recess 11111 can be one or more.

[0593] For example, the electrode body 111 has an electrode recess 11111 on one side along its own thickness direction; alternatively, the electrode body 111 has electrode recesses 11111 on both sides along its own thickness direction.

[0594] For example, in the thickness direction of the electrode body 111, the depth of the electrode recess 11111 is less than or equal to the thickness of the active material layer 1111. The thickness of the active material layer 1111 is the thickness of the active material layer 1111 located on one side of the current collector body 1112.

[0595] By setting the electrode recess 11111, the pressure between the electrode bodies 111 of the two electrodes 11 can be reduced, and the binding effect of the electrode bodies 111 of the two electrodes 11 on each other can be weakened. When thermal runaway occurs in the cylindrical battery cell 7, the two first electrode winding portions 13 can easily separate under the action of air pressure and be discharged to the outside of the casing 20 at least partially through the exhaust channel, thereby increasing the exhaust rate, reducing the risk of explosion of the cylindrical battery cell 7, and improving the reliability of the cylindrical battery cell 7.

[0596] The electrode recess 11111 can also increase the gap between the electrode bodies 111 of the two electrodes 11. During the cycling process of the cylindrical battery cell 7, the electrode recess 11111 can provide space for the expansion of the active material layer 1111 of the negative electrode 11b, reduce the pressure between the electrode bodies 111 of the two electrodes 11, thereby reducing the compression of the electrolyte in the internal pores of the active material layer 1111, reducing the concentration difference of electrolyte in different regions inside the electrode 11, and improving the cycling performance of the cylindrical battery cell 7 with a larger diameter. The electrode recess 11111 can reduce the expansion of the electrode assembly 10, thereby reducing the compression of the casing 20, reducing the risk of deformation and cracking of the casing 20, and improving the reliability of the cylindrical battery cell 7.

[0597] The electrode recess 11111 can also accommodate electrolyte, which helps the electrolyte to wet the electrode body 111.

[0598] In some embodiments, a portion of the plurality of electrode recesses 11111 is disposed in the first electrode winding portion 13, and another portion of the plurality of electrode recesses 11111 is disposed in the second electrode winding portion 14.

[0599] In some embodiments, the electrode recess 11111 is formed on the active material layer 1111, which can reduce the influence of the electrode recess 11111 on the current flow capacity of the electrode body 111.

[0600] In some embodiments, the depth of the electrode recess 11111 is less than the thickness of the active material layer 1111 in the thickness direction of the electrode body 111. Optionally, the ratio of the depth of the electrode recess 11111 to the thickness of the active material layer 1111 in the thickness direction of the electrode body 111 is 0.01-0.5.

[0601] In some embodiments, the electrode recess 11111 extends through the electrode body 111 along the axial direction Z to increase the gap between the electrode bodies 111 of the two electrodes 11, reduce the binding effect of the electrode bodies 111 of the two electrodes 11 on each other, and facilitate the two first electrode winding portions 13 to extend to the outside of the outer casing 20.

[0602] The electrode recess 11111 extends through the electrode body 111 along the axial direction Z, which can also improve the wettability of the electrolyte.

[0603] In some embodiments, the electrode recess 11111 extends along the axial direction Z.

[0604] In some embodiments, the shape of the cross section of the electrode recess 11111 perpendicular to the axial direction Z is triangular, trapezoidal, semi-circular or other shapes.

[0605] In some embodiments, a plurality of electrode recesses 11111 are spaced apart along the winding direction V. The plurality of electrode recesses 11111 can further reduce the binding effect of the electrode bodies 111 of the two electrodes 11 on each other, which is beneficial for the two first electrode winding portions 13 to extend to the outside of the housing 20.

[0606] In some embodiments, the electrode body 111 of the positive electrode 11a is provided with an electrode recess 11111.

[0607] In some embodiments, the electrode body 111 of the negative electrode 11b is provided with an electrode recess 11111.

[0608] Figure 29 is a partial cross-sectional schematic diagram of a cylindrical battery cell provided in some other embodiments of this application.

[0609] Referring to FIG29, in some embodiments, the sidewall 212 is provided with an inwardly protruding protrusion 2121.

[0610] For example, the protrusion 2121 can be a solid structure or a hollow structure.

[0611] In some embodiments, at least a portion of the protrusion 2121 is located between the second end wall 20a and the second tab 112b in the axial direction Z.

[0612] The protrusion 2121 overlaps with the second tab 112b in the axial direction Z. When the cylindrical battery cell 7 is subjected to external impact, it can restrict the movement of the second tab 112b in the axial direction Z and reduce the risk of failure of the connection between the second tab 112b and the second current collector 40b.

[0613] In some embodiments, the second current collector 40b is connected to the protrusion 2121. As an example, the second current collector 40b may be welded to the protrusion 2121; alternatively, the second current collector 40b may also be press-fitted to the protrusion 2121.

[0614] For example, the second current collector 40b is connected to the side of the protrusion 2121 facing the second electrode 112b, or it can be connected to the side of the protrusion 2121 facing the end cap 22.

[0615] Connecting the second current collector 40b to the protrusion 2121 can shorten the conductive path between the second tab 112b and the first end wall 211, reduce resistance, reduce heat generation, and improve the cycle performance of the cylindrical battery cell 7.

[0616] In some embodiments, a portion of the second current collector 40b is located on the side of the protrusion 2121 facing the second end wall 20a and is connected to the protrusion 2121. The second current collector 40b is connected to the protrusion 2121 from the outside of the protrusion 2121, which can reduce assembly difficulty.

[0617] In some embodiments, the second current collector 40b is welded to the protrusion 2121.

[0618] In some embodiments, a third recess 2122 is provided on the outer side of the sidewall 212, and the third recess 2122 corresponds to the position of the protrusion 2121. As an example, after the electrode assembly 10 is installed into the housing 21, the inwardly protruding protrusion 2121 is formed by pressing the sidewall 212 from the outside.

[0619] In some embodiments, the sidewall 212 further includes a crimping portion 2123, which extends from the end of the protrusion 2121 away from the first endwall 211 and surrounds the end cap 22.

[0620] 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.

[0621] In some embodiments, the cylindrical battery cell 7 further includes an insulating member 70, which is disposed between the sidewall 212 and the end cap 22 and insulates the end cap 22 from the sidewall 212.

[0622] In some embodiments, a portion of the insulating member 70 is located between the second current collector 40b and the end cap 22 to insulate the second current collector 40b from the end cap 22.

[0623] According to some embodiments of this application, this application also provides a battery device including a plurality of cylindrical battery cells 7 of any of the above embodiments.

[0624] According to some embodiments of this application, this application also provides an electrical device, including a cylindrical battery cell 7 of 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.

[0625] Referring to Figures 4 to 15, this application embodiment provides a cylindrical battery cell 7, which includes a housing 20, an electrode assembly 10, electrode terminals 30, and two current collectors 40. The electrode assembly 10 and the current collectors 40 are disposed within the housing 20.

[0626] The outer casing 20 includes a first end wall 211, a second end wall 20a, and a side wall 212. The first end wall 211 and the second end wall 20a are respectively disposed at both ends of the side wall 212 along the axial direction Z of the cylindrical battery cell 7. Electrode terminals 30 are disposed on the first end wall 211. A pressure relief portion 61 is provided on the second end wall 20a.

[0627] The electrode assembly 10 has a wound structure and includes two electrodes 11 with opposite polarities. The two electrodes 11 include electrode bodies 111 and tabs 112 arranged along the Z-axis. At least a portion of the electrode bodies 111 is coated with an active material layer 1111, while the tabs 112 are not coated with the active material layer 1111.

[0628] In the two electrodes 11, the tab 112 of one electrode 11 is the first tab 112a, and the tab 112 of the other electrode 11 is the second tab 112b. The first tab 112a and the second tab 112b are respectively located at opposite ends of the electrode assembly 10 along the axial direction Z.

[0629] Along the Z-axis, both ends of the electrode assembly 10 are provided with current collectors 40, and the current collectors 40 at both ends of the electrode assembly 10 are respectively the first current collector 40a and the second current collector 40b. The first tab 112a is the positive tab, and the second tab 112b is the negative tab.

[0630] The first tab 112a is electrically connected to the electrode terminal 30 through the first current collector 40a, and the second tab 112b is electrically connected to the first end wall 211 through the second current collector 40b and the side wall 212.

[0631] The electrode tab 112 includes a first electrode tab winding portion 1121 and a second electrode tab winding portion 1122 located outside the first electrode tab winding portion 1121. The current collector 40 is welded to the second electrode tab winding portion 1122 and forms a first welding portion W1. The current collector 40 is not welded to the first electrode tab winding portion 1121. The first electrode tab winding portion 1121 is connected to the first welding portion W1 at one end near the second electrode tab winding portion 1122 along the winding direction V of the electrode assembly 10.

[0632] The electrode 11 includes a first electrode winding portion 13 disposed opposite to the pressure relief portion 61 along the axial direction Z, and a first electrode ear winding portion 1121 is formed in part of the first electrode winding portion 13; the pressure relief portion 61 is configured to open and form an exhaust channel when the pressure value inside the housing 20 reaches a threshold, and at least a portion of the first electrode winding portion 13 is discharged to the outside of the housing 20 through the exhaust channel.

[0633] Both the first electrode tab 112a and the second electrode tab 112b include a first electrode tab winding portion 1121 and a second electrode tab winding portion 1122. The first current collector 40a is welded to the second electrode tab winding portion 1122 of the first electrode tab 112a, but not to the first electrode tab winding portion 1121 of the first electrode tab 112a; the second current collector 40b is welded to the second electrode tab winding portion 1122 of the second electrode tab 112b, but not to the first electrode tab winding portion 1121 of the second electrode tab 112b.

[0634] The first current collector 40a is welded to the electrode terminal 30, and the second current collector 40b is welded to the second end wall 20a.

[0635] The electrode 11 has a winding start end E1 and a winding end end E2 at its two ends along the winding direction V. The first electrode lug winding portion 1121 has a winding start end E1, and the second electrode lug winding portion 1122 has a winding end end E2. The first electrode lug winding portion 1121 has a first notch G1; along the winding direction V, the first notch G1 extends inward to the winding start end E1; along the direction from the electrode body 111 to the electrode lug 112, the first notch G1 extends to the end face of the electrode lug 112 away from the electrode body 111. In the radial direction R of the electrode assembly 10, the first notch G1 is located inside the first welding portion W1.

[0636] The second tab winding portion 1122 near the winding end E2 is provided with a second notch G2. The second notch G2 extends outward along the winding direction V to the winding end E2. Along the direction from the electrode body 111 to the tab 112, the second notch G2 extends to the end face of the tab 112 away from the electrode body 111.

[0637] The first electrode lug winding portion 1121 includes a first coil portion 11211 and a second coil portion 11212 located outside the first coil portion 11211, the second coil portion 11212 being connected to the second electrode lug winding portion 1122. In the axial direction Z, the second electrode lug winding portion 1122 extends beyond the first coil portion 11211 in a direction away from the electrode body 111, and the second coil portion 11212 extends beyond the first coil portion 11211 in a direction away from the electrode body 111.

[0638] The electrode assembly 10 has a central hole 15 that extends along the axial direction Z. A first electrode lug winding portion 1121 is disposed around the outer periphery of the central hole 15, and the central hole 15 and the pressure relief portion 61 are disposed opposite each other along the axial direction Z.

[0639] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0640] 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, comprising: The outer casing has a pressure relief section at at least one end along the axial direction of the cylindrical battery cell; An electrode assembly, at least partially disposed within the housing, is a wound structure and includes two electrodes with opposite polarities. At least one of the electrodes includes an electrode body and an electrode tab arranged along the axial direction. At least a portion of the electrode body is coated with an active material layer, and at least a portion of the electrode tab is not coated with the active material layer. The current collection component is at least partially disposed within the housing; The electrode lug includes a first electrode lug winding portion and a second electrode lug winding portion located outside the first electrode lug winding portion. The current collecting member is welded to the second electrode lug winding portion to form a first weld portion, and the current collecting member is not welded to the first electrode lug winding portion. The electrode sheet includes a first electrode sheet winding portion, and the first electrode lug winding portion is formed on a part of the first electrode sheet winding portion. On a projection plane perpendicular to the axial direction, the orthographic projection of the first electrode sheet winding portion at least partially overlaps with the orthographic projection of the pressure relief portion. The pressure relief portion is configured to at least partially open and form an exhaust channel when pressure is released, and at least a portion of the first electrode sheet winding portion is released to the outside of the housing through the exhaust channel.

2. The cylindrical battery cell according to claim 1, wherein, The first electrode ear winding portion includes a first loop portion; In the axial direction, the second electrode lug winding portion extends beyond the first coil portion in a direction away from the electrode body.

3. The cylindrical battery cell according to claim 2, comprising electrode terminals disposed on the housing, the electrode terminals being welded to the current collector to form a second welded portion; On a projection plane perpendicular to the axis, the orthographic projection of the second welded portion is located outside the orthographic projection of the first ring portion.

4. The cylindrical battery cell according to claim 2 or 3, wherein, The first electrode loop winding portion includes a second loop portion located outside the first loop portion, and the second loop portion is connected to the second electrode loop winding portion and the first loop portion; In the axial direction, the second ring extends beyond the first ring in a direction away from the electrode body.

5. The cylindrical battery cell according to claim 4, wherein, The electrode tab includes a plurality of segments distributed along the winding direction of the electrode assembly, and a cutting groove is provided between any two adjacent segments along the winding direction. At least a portion of the plurality of segments are formed in a part of the second ring portion; In a projection plane perpendicular to the axial direction, the orthographic projection of the bottom surface of at least one of the cut-off grooves lies within the orthographic projection of the pressure relief section.

6. The cylindrical battery cell according to claim 5, comprising an electrode terminal disposed on the housing, the electrode terminal being welded to the current collector to form a second welded portion; On a projection plane perpendicular to the axial direction, the two ends of the orthographic projection of the second welded portion have a first projection endpoint and a second projection endpoint, respectively. The first projection endpoint is closer to the central axis of the cylindrical battery cell than the second projection endpoint. The area between the first arc line passing through the first projection endpoint and surrounding the first ring portion and the second arc line passing through the second projection endpoint and surrounding the first ring portion is the first transverse region. At least a portion of the cut-off grooves form a first group of cut-off grooves. In the first group of cut-off grooves, the orthographic projection of the bottom surface of all the cut-off grooves is located within the first transverse region. in, In the first set of cut-off slots, the number of turns of a single cut-off slot is ≤3; and / or, in the first set of cut-off slots, the number of cut-off slots that are radially opposite and interconnected along the electrode assembly is ≤3.

7. The cylindrical battery cell according to any one of claims 1-6, wherein, The electrode tab includes a plurality of segments distributed along the winding direction of the electrode assembly, and a cutting groove is provided between any two adjacent segments along the winding direction. At least a portion of the plurality of segments is formed in a part of the second electrode ear winding portion; The current collector is welded to the section of the second electrode ear winding portion and forms the first welded portion; In a projection plane perpendicular to the axial direction, the orthographic projection of the bottom surface of at least one of the cut-off grooves lies within the orthographic projection of the pressure relief section.

8. The cylindrical battery cell according to claim 7, wherein, On a projection plane perpendicular to the axial direction, the two ends of the orthographic projection of the first weld portion have a third projection endpoint and a fourth projection endpoint, respectively. The third projection endpoint is closer to the central axis of the cylindrical battery cell than the fourth projection endpoint. The area between the third arc line that passes through the third projection endpoint and surrounds the first electrode loop portion and the fourth arc line that passes through the fourth projection endpoint and surrounds the first electrode loop portion is the second transverse region. At least a portion of the cut-off grooves form a second set of cut-off grooves. In the second set of cut-off grooves, the orthographic projection of the bottom surface of all the cut-off grooves is located within the second transverse region. Wherein, in the second set of cut-off grooves, the number of turns of a single cut-off groove is ≤3; and / or, in the second set of cut-off grooves, the number of cut-off grooves that are radially opposite and interconnected along the electrode assembly is ≤3.

9. The cylindrical battery cell according to claim 7 or 8, wherein, Among the multiple segments of the second electrode loop winding portion, the segment furthest from the first electrode loop winding portion is wound at least one turn along the winding direction.

10. The cylindrical battery cell according to any one of claims 5-9, wherein, At least one of the electrode sheets includes a positive electrode sheet, the positive electrode sheet including the electrode sheet body, the tab and an insulating layer, the tab of the positive electrode sheet not coated with the active material layer; in the axial direction, at least a portion of the insulating layer is disposed on the end region of the tab near the electrode sheet body, and the cut-off piece is located on the side of the insulating layer opposite to the electrode sheet body.

11. The cylindrical battery cell according to any one of claims 5-10, wherein, At least one of the segments has a bent section at one end in the axial direction; The bending segment includes at least one first bending portion bent relative to the electrode body in a direction close to the central axis of the cylindrical battery cell; and / or, the bending segment includes at least one second bending portion bent relative to the electrode body in a direction away from the central axis of the cylindrical battery cell.

12. The cylindrical battery cell according to claim 11, wherein, The bending section includes a first bending portion and a second bending portion, both of which are bent radially along the electrode assembly.

13. The cylindrical battery cell according to claim 11 or 12, wherein, The bending section includes a first bending portion and a second bending portion, which are alternately arranged along the axial direction.

14. The cylindrical battery cell according to any one of claims 11-13, wherein, Each of the segments has a bent section at one end in the axial direction.

15. The cylindrical battery cell according to any one of claims 5-14, wherein, The electrode tab further includes a transition connection portion, and the electrode body, the transition connection portion, and the segment are arranged sequentially along the axial direction; the transition connection portion and two segments adjacent to each other along the winding direction form the cutting groove, and the bottom surface of the cutting groove is formed on one side edge of the transition connection portion used to connect the segments.

16. The cylindrical battery cell according to claim 15, wherein, The dimension of one side edge of each of the segments used to connect the transition connection portion in the winding direction of the electrode assembly is L1, and the sum of the dimensions of the transition connection portion and the segments in the axial direction is L2, where 0.01≤L2 / L1≤0.

3.

17. The cylindrical battery cell according to claim 15 or 16, wherein, The dimension of the transition connection in the axial direction is L3, where 0.1mm≤L3≤2mm.

18. The cylindrical battery cell according to any one of claims 5-17, wherein, The electrode tab is provided with a plurality of cutting grooves, and the cutting grooves and the cutting pieces are arranged alternately along the winding direction of the electrode assembly.

19. The cylindrical battery cell according to any one of claims 5-18, wherein, In the axial direction, the size of the truncated piece along the winding direction of the electrode assembly tends to decrease in the direction away from the electrode body.

20. The cylindrical battery cell according to any one of claims 1-19, wherein, On a projection plane perpendicular to the axis, the orthographic projection of the first electrode ear winding portion lies within the orthographic projection of the pressure relief portion.

21. The cylindrical battery cell according to any one of claims 1-20, wherein, The electrode sheet has a winding start end and a winding end end at both ends along the winding direction of the electrode assembly; In the radial direction of the electrode assembly, the winding start end is closer to the central axis of the cylindrical battery cell than the winding end end; The first electrode ear winding portion is provided with the winding starting end. In the projection plane perpendicular to the axis, the orthographic projection of the winding starting end is located in the orthographic projection of the pressure relief portion.

22. The cylindrical battery cell according to any one of claims 1-21, wherein, The electrode assembly is provided with a central hole, which extends along the axial direction; The first electrode lug is wound around the outer periphery of the central hole at intervals, and in a projection plane perpendicular to the axial direction, the orthographic projection of the central hole is located within the orthographic projection of the pressure relief part.

23. The cylindrical battery cell according to claim 22, wherein, The outer diameter of the electrode assembly is D1, and the diameter of the central hole is D2, where D2 / D1 ∈ [5%, 25%].

24. The cylindrical battery cell according to any one of claims 1-23, wherein, In a projection plane perpendicular to the axis, the orthographic projection of the second pole lug winding portion at least partially overlaps with the orthographic projection of the pressure relief portion.

25. The cylindrical battery cell according to any one of claims 1-24, wherein, In the winding direction of the electrode assembly, the length of the second electrode lug winding portion is greater than the length of the first electrode lug winding portion.

26. The cylindrical battery cell according to any one of claims 1-25, wherein, Both electrodes include an electrode body and an electrode tab, wherein the electrode tab of one electrode is a first electrode tab and the electrode tab of the other electrode is a second electrode tab. The first electrode tab and the second electrode tab are respectively disposed at opposite ends of the electrode assembly along the axial direction, and both the first electrode tab and the second electrode tab include a first electrode tab winding portion and a second electrode tab winding portion. Along the axial direction, both ends of the electrode assembly are provided with current collecting components, and the current collecting components at both ends of the electrode assembly are respectively a first current collecting component and a second current collecting component; the first current collecting component is welded to the second electrode ear winding portion of the first electrode ear, but not welded to the first electrode ear winding portion of the first electrode ear; the second current collecting component is welded to the second electrode ear winding portion of the second electrode ear, but not welded to the first electrode ear winding portion of the second electrode ear.

27. The cylindrical battery cell according to claim 26, wherein, The outer casing includes a first end wall, a second end wall, and a side wall, wherein the first end wall and the second end wall are respectively disposed at both ends of the side wall along the axial direction; The cylindrical battery cell includes an electrode terminal disposed on the first end wall. The first tab is electrically connected to the electrode terminal through the first current collector, and the second tab is electrically connected to the first end wall through the second current collector and the side wall.

28. The cylindrical battery cell according to claim 27, wherein, The second end wall is welded to the second current collector, and the second end wall is electrically connected to the side wall.

29. The cylindrical battery cell according to claim 28, wherein, The sidewall is provided with an inwardly protruding part, and the second current collecting member is connected to the protruding part.

30. The cylindrical battery cell according to claim 29, wherein, A portion of the second current collector is located on the side of the protrusion facing the second end wall and is connected to the protrusion.

31. The cylindrical battery cell according to any one of claims 27-30, wherein, The pressure relief section is provided on the second end wall.

32. The cylindrical battery cell according to any one of claims 26-31, wherein, The first electrode is the positive electrode, and the second electrode is the negative electrode.

33. The cylindrical battery cell according to any one of claims 1-32, wherein, The two electrodes include a positive electrode and a negative electrode, and both the positive electrode and the negative electrode include an electrode body and an electrode tab; The tabs of the positive electrode are not coated with the active material layer; and / or, the tabs of the negative electrode are not coated with the active material layer.

34. The cylindrical battery cell according to any one of claims 1-33, wherein, At least one of the electrodes includes a positive electrode, the positive electrode including the electrode body, the tab and an insulating layer, the tab of the positive electrode not coated with the active material layer; in the axial direction, at least a portion of the insulating layer is disposed on the end region of the tab near the electrode body.

35. The cylindrical battery cell according to any one of claims 1-34, wherein, At least one of the electrode sheets has a winding start end and a winding end end at both ends along the winding direction of the electrode assembly, the first electrode ear winding portion is provided with the winding start end, and the second electrode ear winding portion is provided with the winding end end; In the radial direction of the electrode assembly, the winding start end is closer to the central axis of the cylindrical battery cell than the winding end end; The first electrode lug winding portion near the winding start end is provided with a first notch; the first notch penetrates the winding start end along the winding direction and penetrates the end face of the electrode lug away from the electrode body along the axial direction; In the radial direction of the electrode assembly, the first notch is located on the side of the first weld portion near the central axis of the cylindrical battery cell.

36. The cylindrical battery cell according to any one of claims 1-35, wherein, At least one of the electrode sheets has a winding start end and a winding end end at both ends along the winding direction of the electrode assembly, the first electrode ear winding portion is provided with the winding start end, and the second electrode ear winding portion is provided with the winding end end; In the radial direction of the electrode assembly, the winding start end is closer to the central axis of the cylindrical battery cell than the winding end end; The second electrode lug winding portion near the winding end is provided with a second notch groove. The second notch groove penetrates the winding end along the winding direction and penetrates the end face of the electrode lug away from the electrode body along the axial direction.

37. The cylindrical battery cell according to claim 36, wherein, In the radial direction of the electrode assembly, the first weld portion is closer to the central axis of the cylindrical battery cell than the second notch.

38. The cylindrical battery cell according to any one of claims 1-37, wherein, The flow collecting component is provided with an exhaust through hole and a plurality of guide portions, the exhaust through hole extending along the axial direction; the plurality of guide portions are arranged around the outer periphery of the exhaust through hole; In a projection plane perpendicular to the axial direction, the orthographic projection of the exhaust port is located within the orthographic projection of the pressure relief portion, and the orthographic projection of the exhaust port at least partially overlaps with the orthographic projection of the first electrode ear winding portion.

39. The cylindrical battery cell according to claim 38, wherein, The guide portion extends to the exhaust port; or... The guide portion is spaced apart from the wall of the exhaust hole, and the minimum distance between the guide portion and the wall of the exhaust hole is less than or equal to 10 mm.

40. The cylindrical battery cell according to claim 38 or 39, wherein, The housing includes a weak portion surrounding the periphery of the pressure relief section, at least a portion of which is configured to disconnect upon pressure relief to open the pressure relief section; On a projection plane perpendicular to the axial direction, along the radial direction of the electrode assembly, the orthographic projection of the end of the guide portion away from the exhaust port is located outside the orthographic projection of the weak portion or coincides with the orthographic projection of the weak portion.

41. The cylindrical battery cell according to any one of claims 38-40, wherein, The electrode assembly is provided with a central hole extending along the axial direction, the first electrode lug winding portion is arranged around the outer periphery of the central hole, and the exhaust port is opposite to and communicates with the central hole along the axial direction. In a projection plane perpendicular to the axis, the orthographic projection of the central hole lies within the orthographic projection of the pressure relief section.

42. The cylindrical battery cell according to any one of claims 1-41, wherein, Both of the aforementioned electrodes include the first electrode winding portion; A gap is provided between the electrode bodies of the two first electrode winding portions.

43. The cylindrical battery cell according to claim 42, wherein, At least a portion of the gap has a radial dimension of 5 μm to 60 μm.

44. The cylindrical battery cell according to claim 42, wherein, The surface of the electrode body is provided with multiple electrode recesses; At least a portion of the plurality of electrode recesses are formed in the first electrode winding portion.

45. The cylindrical battery cell according to claim 44, wherein, The electrode recess is formed in the active material layer.

46. ​​The cylindrical battery cell according to claim 44 or 45, wherein, The electrode recess extends through the electrode body along the axial direction.

47. The cylindrical battery cell according to any one of claims 44-46, wherein, The plurality of electrode recesses are spaced apart along the winding direction of the electrode assembly.

48. The cylindrical battery cell according to any one of claims 1-47, wherein, At least one of the electrodes includes a positive electrode, the positive electrode including the electrode body and the electrode tab; The active material layer of the positive electrode sheet includes a positive electrode active material, which includes a layered transition metal oxide. The layered transition metal oxide includes 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.

49. The cylindrical battery cell according to any one of claims 1-48, further comprising an electrolyte contained within the casing; 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.

50. The cylindrical battery cell according to any one of claims 1-49, wherein, The height of the outer casing is 50mm to 150mm; and / or The diameter of the outer casing is 35mm to 80mm.

51. A battery device comprising a plurality of cylindrical battery cells according to any one of claims 1-50.

52. An electrical device comprising a battery device according to claim 51, the battery device being used to provide electrical energy.

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